Hand-held laser scanning head for reading bar code symbols

1. Field of the Invention!

j! The present invention generally relates to laser!

!scanning systems for scanning, reading and/or analyzing bar code ן i! ' !symbols and, more particularly, to a light-weight, easy-to-I manipulate, non-arm-and-wrist-fatiguing, hand-held, narrow-bodied, single-and twin-windowed, laser scanning head supportable entirely oy a user throughout the reading of the symbols. Still more particularly, this invention relates to a field-replaceable laser tubej | ! ¹arranaement to permit rapid and easy tube replacement; to a novel I

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h-aser tube and method of making the same; to an arrangement for, j Ii and method of, controlling a scanning system; to optical passive !

I i _י .!

iblements for increasing the depth of field; to a trigger protective: il '!

:device; and to a one-piece machinable or moldable plastic support י

IIi 'bench and method of making the same.I

I .i j 2. Description of the Prior Artj

I Many industries, particularly the grocery and food !

h. . ΐ ;processing industry, have begun to designate their products with i!a unique bar code symbol consisting of a series of lines and spaces; !1 lof varying widths. Various bar code readers and laser scanning systems have been developed to decode the symbol pattern to a multiple digit representation for check-out and inventory purposes.

Aside from the conventional contact-type and non!!contact-type wand or pen bar code readers, true laser scanners, !*such as point-of-sale or deck scanners of the moving-beam or fixedlj !¹beam type, have been built into stationary counters. However,these '!deck scanners are large, massive, stationary installations. Some Ij !!symbol-bearing objects are too heavy, or too big, or too inconveni:i !*ent to be brought to the stationary scanning installation. Some

-objects may be stationary themselves.

In order to provide a mobile scanning system, semi- j I portable laser scanning heads, such as disclosed in U.S. 4,251,796;

were designed to permit the user to bring the scanning head to j the object. However, such semi-portable heads weighed over three 1 i pounds, had to be partially supported by the object itself, and j were too heavy and somewhat difficult to readily manipulate, j particularly for those assembly-line applications where a user j was routinely required to repetitively manipulate the semi-portable head many times per minute, every hour and on a daily basis. ;

I

More modern miniature laser scanners weighing on the 1 order of two and one-half pounds, such as described in U-. C. C«־.

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Scanning DysLinn aiid Scanning Methods,״and os&-igned׳to the same. IU.J V-S ¹¹,¹¾¾ . I ?^E-ignee _the—p-resent—ftfT 1 י a t. נ ry !_ב ^arecently been proposec י j to orovide a more truly portable laser scanning head which is J supportable entirely by the user during the reading of the bar code symbols. Although generally satisfactory for its intended purpose, this fully portable head had a rather large case width ;

I due to the fact that the laser beam generated within the head was ;

required to be swept over a wide field of view across the bar code: symbol, which is located in the vicinity of a reference place j located exteriorly of the housing. The swept laser beam, which i!

was accommodated entirely in the wide-bodied head, therefore, required a great deal of dead space within the head. This l dead space caused the case width to be unnecessarily large, and ’1 undesirably added to the overall size and weight of the head, i * ;1 thereby detracting somewhat from its features of ease of manipul1*

I ation and full portability. .

I i Another drawback of the wide-bodied head was that the

־2־ case width increased from the rear towards the front of the head, as considered in the direction from the housing towards the reference plane, with the result that the front or nose of the j head had a wide' snout. In a preferred embodiment, the wide-bodied head had a gun-shaped configuration. It was desirable in some j applications to insert the gun-shaped head, when not in use, into ן a user-supported holster of the kind traditionally used to receive.

and support firearms. However, the wide snout on the wide-bodied head did not lend itself to conveniently fit in the traditional gun holster. Hence, the wide-bodied heads were typically tossed and left on the nearest table, and were prone to being damaged, misplaced and lost.

! Still another drawback associated with the semi-portable and wide-bodied heads was that any dirt specks on the exit window i ji : through which the laser beam exited en route to the bar code ί I 'ί symbol, affected the laser scan at the symbol. The greater the ! !1ΐ i| distance between the exit window and the symbol at the reference : li -’ ϋ olane, the less of a potential malfunction would result from dirt j l| ־I ;1 specks on the exit window. However, the known semi-portable and ; |iί

I; wide-bodied heads were too dirt-sensitive for some applications ; |jί

I inasmuch as the exit window was too undesirably close to thereference plare.j ; Yet another drawback of the prior art laser scanning

I i heads was that laser tube replacement generally required skilled i :1 personnel using specialized equipment. For example, in one >! technique, the replacement tube was mounted on a bracket which was

I¹ ׳ .I , i j then positioned by adjusting screws until the replacement tube !

i!

| i was properly aligned with the optical system. This was time- and ' labor-consuming, and required a skilled technician, nique involved a mounting bracket on which the tube

Another tech was pre-3aligned. The bracket and the tube were changed together as an integral assembly. Although this technique allowed replacement ί by unskilled people, the tube still had to be initially aligned j to the mounting bracket by a skilled technician. In both tech!

il nigues, the output and non-output ends of the used laser tube had j il i

I to be unsoldered from their respective electrical power wires, ן I and thereupon, the output and non-output ends of the fresh tube j !1 had to be soldered to the respective electrical power wires. This!

i soldering operation was likewise time- and labor-consuming, and !

I . . 1

I required special tools which might or might not have been available at a given field installation.

The optical system of a laser scanner head generally used ! a negative lens at the output end of the laser tube to diverge the ! collimated laser beam, and thereupon, used a positive lens to i | focus the diverging laser beam to a spot of predetermined diameter;

i at a reference plane located exteriorly of the head. The negative; lens represented a component of given weight, size and cost, and ; in the context of a'laser scanner head to be made as light-weight,! miniature and inexpensive as possible, a component which it was desirable to eliminate. 1

SUMMARY OF THE INVENTION

1. Objects of the Invention

Accordingly, it is the general object of the present invention to overcome the aforementioned drawbacks of the prior !art laser scanning heads.

i i Another object;.of this invention is to reduce the rather

1! .* | large case width heretofore required in prior art wide-bodied

B laser scanning heads. .>- י ן, j Still another object of this invention is to eliminate li

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Η |i i!

il the amount of dead space within the head.

i . .

Yet another object of this invention is to provide a 'i !1 !1 !! 'i 11 h i 1 |

!1

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il i!

li !1 li li !i i

ί

I i

I laser scanning head which is so light-in-weight and small-involume» that it can be easily held in a user's hand without causing arm- and wrist-fatigue, while being easy-to-manipulate, even for those assembly-line applications where the user is routinely required to repetitively manipulate the head many times per minute, every hour, and on a daily basis.

An additional object of this invention is to provide a fully portable laser scanning head weighing on the order of one pound.

A further object of this invention is to eliminate the wide snout heretofore present on prior art wide-bodied laser scanning heads.

Still another object of this invention is to provide a narrow-bodied laser scanning head which can readily be received and supported in a traditional V-shaped gun holster, thereby preventing possible’ damage to, and misplacement and loss of, the head.

Yet another object of this invention is to prevent dirt , specks on the laser exit window of the laser scanning head from

I adversely affecting the reading of the bar code symbol. i !

Another object of this invention is to automatically ;

optically align the laser tube with the optic system during tube ;

I replacement without requiring skilled technicians or specialized !

I equipment to effect the replacement.j •j

Still another object of this invention is to replace the : ί’ used laser tube in the head without requiring any desoldering :

or soldering of any electrical power wires.:

'J:

Yet another object of this invention is to eliminate !

!i the negative lens of the optical system, and thereby reduce the overall weight, size and cost of the head.

A further object of this invention is to make the field : !1

I of view of the incident laser beam traveling towards the symbol ii and/or the reflected laser beam traveling back from the symbol!

substantially independent of the case width of the head.

An additional object of this invention is to make the I

I field of view of the incident laser beam and/or the reflected laser beam larger than the case width of the head.

A further object of this invention is to provide a laser scanning head which is shock-resistant and resists twisting j i of the head. ;

| Yet a further object of this invention is to minimize i ! battery power drain by actuating all of the actuatable components j in the laser scanning head only when they are operative to read i and process the symbol, and by deactuating all of the actuatable j components in the head after the symbol reading and processing has; been concluded. i

Still a further object of this invention is to independ- j ently actuate and deactuate all of the actuatable components in the laser scanning head by independently operable means on the head and remote therefrom.

Another object of this invention is to eliminate the electrical power and communications cable between the laser scanning head and the remainder of the scanning system.

Still another object, of this invention is to provide a twin-windowed laser scanning head combining the advantages of

I optimum field of view for the incident laser beam, optimum field ί

[ of view for the reflected laser beam, low spot speed scanning i I I 1 i variation for the laser beam, low sensitivity to dirt specks on ’

I . , . ) : the laser beam exit or scanning window, highlight sensor effective1 ¹ i

I i !i !i ii ness, ease of judging scanning distance to the light sensor, and ί minimum case width.j

I

2. Features of the Invention;

In keeping with these objects and others which will be j apparent hereinafter, one feature of the invention resides,j briefly stated, in a scanning head of a scanning system for read- j ing bar code symbols. The head is preferably of light-weight, ־ narrow-bodied, easy-to-manipulate, non-arm-and-wrist fatiguing, !

i ., and is hand-held and supportable entirely by a user during symbol I \ reading. The head has an elongated body portion and includes a | front region, a rear region, and an intermediate body region j extending between the front and rear regions. The head has a i

I predetermined width defined by a pair of opposing side walls ! spaced transversely apart of each other. In a preferred embodi- ment, the hand-held head has a gun-shaped housing, and has !

i a handle portion mounted below the body portion. i

The head includes a light source means, e.g. a miniature i laser tube or a semiconductor laser diode, mounted within the ! head, for generating an incident light beam. Optic means, e.g. .

i an optical train consisting of at least one lens and light- ;

reflecting mirrors, is also mounted within the head, and is;

operative for directing the incident beam along a light path|

I towards a reference plane located exteriorly of the housing in j

I the vicinity of the front region thereof, and also towards a bar ! ίί ϋ׳ |j code symbol located in the vicinity of the reference plane. Ά I ;1I i reflected light beam is reflected off the symbol, and is directed j I Λ '

I along a light path away from'the reference plane and back towards | !! _k .i :j the housing.j

I

The head further includes scanning means, e.g. a miniature i high-speed scanning motor or a miniature mirrored polygon,, !

mounted within the head at the rear region thereof, for sweeping at least one of the beams, i.e. either the incident beam, or the : 1 reflected beam, or both, over a field of view across the bar code I i symbol. Sensor means, e.g. a pair of miniature photodiodes, is ! also mounted within the head, for detecting the light intensity A in the reflected beam over a field of view across the bar code symbol, and for generating an electrical analog signal indicative of the detected light intensity. Signal processing means, e.g. analog-to-digital processing circuitry, is also mounted within !

the head, for processing the analog signal into a digitized:

i signal to generate therefrom data descriptive of the bar code i i j symbol.:

I In accordance with this invention, window means is ן

i.1 ! mounted on the housing, and in a broad aspect of this invention, j ί a single light-transmissive window is mounted at the rear region ! of the head in close adjacent confronting relationship with the :

i scanning means thereat. The window is configured and positioned i in the light path of the swept beam, i.e., either the incident J I beam, or the reflected beam, or both, to permit the swept beam . to pass through the window and unobstructedly travel exteriorly of and past the front and intermediate body regions of the housing.

Due to the exterior transmission of t.he swept beam outside of the front and intermediate body regions of the housing, j the field of view of the swept beam is substantially independent i of the width of the housing. Put another way, the angular ί !

ί distance through which the incident and/or reflected beams are i ί ίι swept is no longer a function of the width of the housing. The ־ ׳ i ;* incident and/or reflected beams can now be swept over an angular ; i ^j :1 i

I I

ן «

i * » distance which is greater than the.housing width. Furthermore, the angular distance through which the incident and/or reflected beams are swept can be maintained at the industrial standard, and the width of the housing can be made much narrower in comparison to prior art wide-bodied designs. The amount of dead ' space within the head has been significantly reduced. The overall:

i size and weight of the head is likewise much reduced, thereby ; further contributing to the full portability and ease of manipul- | ation features of this invention. The designer of miniaturized laser scanning heads is no longer restricted to wide-bodied head configurations.

Similarly,the wide snout at the front of the prior art ! heads is no longer a design restraint. The narrow-bodied and [

I streamlined design of the head of this invention can readily be I

I received and supported in a traditional V-shaped gun holster, | i thereby preventing possible damage to,and misplacement and loss j of,the head.I • .I

In one preferred embodiment, the window at the rear I i region of the head adjacent the scanning means constitutes a|

I1

I1

I scan window through which the incident beam passes en route to the₍ !

bar code symbol. Another light-transmissive non-scan window is j mounted at the front region of the head in close adjacent confronting relationship with the sensor means also located thereat.

The non-scan window is configured and positioned in the light j path of the reflected beam to permit the latter to pass therethrough to the sensor means. In this twin-windowed embodiment, the closeness of the scan wi'ndow relative to the scanning means j

I maximizes the field of view of the incident beam; and the:

ti closeness of the non-scan window relative to the sensor meansΐ

I ! maximizes the field of view of the reflected beam, and increases | • '1 i!

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arward mounting of the scan window helps to minimize the of dirt specks on the scan window.

In another twin-windowed embodiment, a reversal of parts the rear scan window to be positioned in the light path reflected beam, whereas the front non-scan window is the light sensor signal;. The scan window is advantageously ׳ i located further from the reference plane and the front region j ' I ! of the housing as compared to the location of the non-scan window/ ! This rt i effect I.

I causes of the positioned in the light path of the incident beam. In this embodiment, the light source is mounted at the front of the head in close adjacent confronting relationship with the non-scan I window located thereat. The scanning means remains at the rear of the head adjacent the scan window. In operation, the light j! source illuminates the symbol, and the reflected beam travels i! unobstructedly and exteriorly of and past the front and interi j mediate body regions of the head. The scanning means sweeps the , reflected beam and, in turn, directs the swept beam to the sensor j | means for further processing.

In still another preferred embodiment, only a single window is mounted at the rear of the head in close adjacent confronting relationship with the scanning means thereat. The single window is configured and positioned in the light paths of both the swept incident and reflected beams to permit both

I beams to pass through the window and unobstructedly travel | exteriorly of and past the front and intermediate body regions

I of the head. This retro-reflective scanning is advantageous in 1 some applications, became it eliminates the need for the second window, as described in the earlier twin-windowed embodiments.

I Yet another feature, of this invention resides in a !!

jl y field-replaceable laser tube arrangement which automatically

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H -10־ i . i ; I ;i

J optically aligns the laser tube with the optic system of the head ; during tube replacement without requiring skilled technicians or | snecialized equipment to effect the replacement, and without ;

׳ requiring any desoldering or soldering of any electrical power ! i wires. j

An additional feature of this invention resides in :

eliminatinq the negative lens of the optical system by modifying I i the laser tube of the head to have a diverging output laser beam. !

In prior art designs, the output beam of the laser tube was collimated, i.e. had a substantially flat wavefront. It was j necessary therefore to use a negative lens to diverge the collimated laser beam, and thereupon, to use a positive lens to focus the diverging laser beam to a circular spot of predetermined | diameter at the reference plane. However, by modifying the laser!

;1 tube to have a diverging output beam, the negative lens and itsj .’i i attendant weight, size, space requirements and cost aspects arei

I eliminated, thereby contributing to the overall portability ofj | the head.| | Still other features relate to increasing the depth of !

י field by using optical passive elements rather than electronic | i!

il circuitry, minimizing battery drain by actuating the components ! ί!

in the head only when the symbol is being read, and fabricating j !

an optical support bench by mass-production techniques.:

The novel features which are considered as characteristic; 1 of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construe- !

ן !

ί tion and its method of operation, together with additional objects, li !

ן and advantages thereof, will be best understood from the following * !

description of specific embodiments when read in connection with the accompanying drawings.

־ | BRIEF DESCRIPTION OF THE DRAWINGS !1' i! FIG. 1 is a side sectional view of a gun-shaped, narrow- j J!

;! bodied, twin-windowed embodiment of a laser tube-based portable !

laser scanning head in accordance with this invention;ΐ i

FIG. 2 is a partially broken-away, top sectional view of !;the embodiment of FIG. '1;

FIG.

is a rear sectional view as taken along line 3—3 ! of

FIG. 1;

FIG.

is a top plan sectional view of a detail of the !!embodiment of

FIG.

1, showing the laser, tube and part of the optical train;

FIG.

is a front elevational view of the embodiment of

FIG.

1;

FIG.

is a front perspective view of the

FIG. 1 embodiment on a much smaller scale, and diagramatically shows the interconnection of the head to the remainder of the scanning system;

FIG. 7A is a top plan schematic view of a prior art widebodied head;

FIG. 7B is a top plan schematic view of an alternate, but unacceptable, design of a laser scanning head;

FIG. 7C is a top plan schematic view of another alternate, but unacceptable, design of a laser scanning head;

head

FIG. 7D is a top plan of FIG. 1;

schematic view of the laser scanning

FIG. 8 is a side sectional view of a gun-shaped, narrowbodied, twin-windowed embodiment of a laser diode-based portable laser scanning head in accordance with this invention;

FIG.

is a partially sectioned, top plan view of the embodiment of

FIG.

8;

FIG.

is a side schematic view of a gun-shaped, narrow•., 1 bodied, twin-windowed embodiment of a light-based portable scanning

I head in accordance with this invention;

FIG. 11 is a top plan schematic view of the embodiment of ii FIG.

10;

FIG. 12 is a side schematic view of a gun-shaped, narrow-121 ! bodied, single-windowed, retro-reflective embodiment of a light! based׳scanning .head in accordance with this invention;

l| . _c ;ΐ FIG. 13 is a top plan schematic view of the embodiment of l| !jFTG. 12;

1j FIG. 14 is a partially schematic, rear elevational view of

[I !!the components mounted in the rear region of the FIG. 12 embodiii ment;

FIG. 15 is a field-replaceable laser tube arrangement for use in any of the aforementioned laser tube-based embodiments;

FIG. 16 is a partially schematic, partially sectional, side view of a novel laser tube having a diverging output laser beam !¹made in accordance with one method of this invention; and

I FIG. 17 is a partially schematic, partially sectional, side • view of a novel laser tube having a diverging output laser beam ίί .

ii made in accordance with another method of this invention.

:1

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIGS. 1-6 of the drawings, reference numeral 10 generally identifies a light-weight, narrow-bodied, ii streamlined, narrow-snouted, hand-held, fully portable, easy-toi manipulate, non-arm-and-wrist-fatiguing, twin-windowed laser scanning head supportable entirely by a user for use in a laser i scanning system operative for reading, scanning and/or analyzing j bar code symbols throughout the reading thereof. Such symbols !i comprise a series of lines and spaces of varying widths, which I i !1 pattern decodes to a multiple-digit representation characteristic ii j of the product bearing tjhe symbol. Typical symbol bar codes m current use are the Universal Product Code (UPC), EAN, Codabar 1 i

; and Code 39 . Λ־

Turning now to FIG. 1, the head 10 includes a generally ׳gun-shaped housing having a handle portion 12 and an elongated, !narrow-bodied barrel or body portion 14. The handle portion 12 has a cross-sectional dimension and overall size such that it conveniently fit in the palm of a user's hand. Both the body handle portions are constituted of a light-weight, resilient, shock-resistant, self-supporting material, such as a synthetic ן can and plastic material. The plastic housing is preferably injectionmolded, but can be vacuum-formed or blow-molded to form a thin shell which is hollow and bounds an interior space whose volume measures less than a value which is on the order of cubic inIches. The specific value of 50 cubic inches is not intended to be self-limiting, but has been provided merely to give an approximation of the overall maximum volume and size of the head 10- The overall volume can be less than 50 cubic inches and, indeed, in

I some applications, the volume is on the order of 25 cubic inches. 1

The body portion 14 is generally horizontally elongated along a longitudinal axis, and has a front region 16 at the front end, a raised rear region 18 at the rear end, and an intermediate body region 20 extending between the front and rear regions. The | body portion 14 has a top wall 11 above which the raised rear reg-!

I ion 18 projects, a bottom wall 13 below the top wall, a pair of ί opposed side walls 15, 17 spaced transversely apart of each other ! by a predetermined width dimension, a front wall or nose 19, and a rear wall 21 spaced rearwardly of the frontwall.

A light source means, i.e., laser tube 22 having an anode or output end 23 (see FIG. 4) and a cathode or non-output end 25, is mounted within the body portion 14 i' lengthwise along the longitudinal axis, and is operative for generating an incident colliji mated laser beam. An optic-means, i.e., an optic train, is II ' !!likewise mounted within the body portion, and is operative for directing the plane located region 16, as

I is located in incident beam along a light path towards a reference J exteriorly of the housing in the vicinity of the frori j shown in FIGS. 1 and 2. A bar code symbol to be rea&lt;5 the vicinity of the reference plane, that is, any where within the depth of focus of the incident beam as described below, and the light reflected from the symbol constitutes a re !fleeted laser beam which is directed along a light path away from the reference plane and back towards the housing.

As best shown in FIGS. 4 and 5, the optic train includes an optical bench 24,a negative or concave lens 26 which is fixedly mounted in a cylindrical bore 25 of the bench,a light-reflecting mirror 26'which is fixedly mounted on an inclined surface 27 of the bench, another light-reflecting mirror 28 which is fixedly mounted on another inclined surface 29 of the bench, a positive j or convex lens 30 which is adjustably mounted i ! means of on the bench by a set screw 31, and still another light-reflecting mirror which is adjustably mounted on a bendable metal bracket

33.

which

The optical communicates is snugly received bench 24 with the has an enlarged cylindrical smaller bore 25. The laser recess tube in a cylindrical support sleeve 34 which, in turn, is snugly received in the bore 25. An electrically conductive element or washer 36 is located at the shoulder between the recess 35 and bore 25. The washer 36 makes an electromechanical, non-soldered contact with the output end 23 of the tube. Another electrically conductive element, preferably a

I resilient wire 38, is mounted at the non-ijuttfit end 25 of the tube.

II * :The wire 38 has one coiled end looped around the non-output end

25, an intermediate taut wire portion extending lengthwise of the tube, and its other end is fixedly secured to the bench 24 by the ! set screw 37. The wire 38 is preferably made of a resilient,

I i * !| spring-like material, and its tautness functions much like a |i spring or biasing means for affirmatively urging the output end 23 ן into affirmative, electro-mechanical contact with the washer j| 36. The non-output end 25 is grounded via the wire 38; and a ; high voltage power wire (not shown) from the power supply compon- j j i ΐ ent 40 mounted in the handle portion 12 is electrically connected | H to a ballast resistor 42 mounted in another bore formed in the I

) _י1' !bench 24. The ballast resistor is, in turn, electrically con- j I nected to the washer 36 by a wire, not illustrated for the sake of clarity. It will be noted that neither the output nor nonoutput end of the tube is directly soldered to any electrical wire, a feature which is highly desirable in effecting on-site| tube replacement. The bore 25 and recess 35 are mechanically bore-sighted so that the laser output beam is automatically| optically aligned with the optic train when the sleeve-supported 1

I tube and output end are fully inserted into the recess 35 and bore, 1| i 25, respectively.

I' | The bench 24 is a one-piece light-weight part machined ן

I | Qj. preferably molded by inexpensive mass-production techniques of a dimensionally stable, flame-retardant material, such as Delrin (Trademark), or glass-filled Noryl (Trademark), preferably having a high dielectric breakdown (on the order of 500 volts/ jj mil) . In order to take into account the slight variations in i beam alignment which unavoidably result from different tubes and from tolerance variations in the tube itself, the bore 25, and the recess 35, the very weak negative lens 26 (on the order of i

I -24mm) is mounted very close to the output end of the tube, and

I: all the elements in the optical path are made large enough to j .

g allow the beam to pass unobstructedly even if the beam is not i i !j exactly on center. The close mounting of the weak lens 26, and

H the short optical path (about 38mm) between lenses 26 and 30, Ί

H mean that the optical tolerances in the remainder of the beam path can still be off by about 1/2° without sacrificing system performance. This provides the advantage that the bench can be inexpensively mass-produced with practical tolerances. !

I

Thus, the beam emitted from the output end 23 first _;j passes through the negative lens 26 which functions to diverge j the initially collimated beam. Then, the divergent beam impinges ן I the mirror 26', and is thereupon reflected laterally to impinge the

I mirror 28, whereupon the beam is reflected upwardly to pass ! through the positive lens 30 which is operative to converge the divergent beam to a generally circular spot of approximately an mil. tc .10 mil diameter at the reference plane. The spot

I size remains approximately constant throughout the depth of focus at either side of the reference plane. The converging beam from the lens 30 impinges on the adjustable mirror 32, and is thereupon laterally reflected to a scanning mirror 44 which forms part of the scanning means.

The scanning means is preferably a high-speed scanner motor 46 of the type shown and described in co-pending

ט. S. Appl. Ser. No. 125,768, filed February 29, 1980, entitled Portable Laser Scanning System and Scanning Methods, *Whxrzj _ר. .

¾1(1 assignee to the same assignee as the present application.

A . . . u .

The entire contents of said .־;.־'־. are incorporated herein by reference and made part of this application. For purposes of this application, it is sufficient to point out that the scanner motor 46 has an output shaft 41 on which a support plate 43 is fixedly mounted. The scanning mirror 44 is fixedly mounted on the plate 43. The motor 46 is driven to reciprocally and ! repetitively oscillate the shaft in alternate circumferential

I directions over arc lengths of any desired size, typically less than 360°, and at a rate of speed on the order of a plurality of oscillations per second. In a preferred embodiment j of this invention, the Scanning mirror 44 and the shaft are i ! jointly oscillated so that the scanning mirror repetitively sweeps the beam impinging thereon through an angular distance ji.

ί יί

i.

,ί !A or an arc length of about 25° and at a rate of about 40 oscil- !

lations per second.!

I

I Stop means, i.e., an abutment 48, is fixedly mounted on >

|a bracket 49 which is, in turn, mounted on the bench 24. The abut-;

Hment 48 is located in the path of oscillating movement of the *plate 43 for the scanning mirror 44, for preventing the mirror from !making a complete 360° rotation during shipping. The abutment | never strikes the mirror during scanning; the abutment serves to j

I keep the mirror properly aligned, that is, always facing toi wards the front of the head.

The scanning motor 46 is mounted on the bench 24 slightly offset from the longitudinal axis. Other miniature !scanning elements can be utilized. For example, miniature poly !gons driven by motors can be used, or the various bimorph scanning ii ¹ioscillatina elements described in U.S. 4, 251, 798 can be used, ijor the penta-bimorph element described m ^,־ -.r-.--. 'י- !1 . ¹ .

^,י .; 1. -;1 י can be used, or the miniature polygon element _n U.S.L.^.AIb. .....

![described in «co-pendi ng —S-^-Appim—&amp;«־- No.——9 45-;—fiicd—¹ ’I |March —L&amp;&amp;0,—entitled Portable Ctand-fiTone Desk-Top Laser־ ;!Scanning Workstation For InLulliguJlL'TdLd Auuuiaition Tuiminal ωτΰ־ .Method of Cn_?nnHuj_r״ assigned to the ׳ent application, the entire contents of )!rated herein by reference and made part II be used.

same assignee as the preswhich are hereby incorpoof this disclosure, can

Although only a single scanner element is shown in the ;!drawings for cyclically sweeping the laser beam across the symbol [ ii ialong a predetermined direction (X-axis scanninc) lengthwise i * ¹thereof, it will be understood that another scanner element may !1. .

jfc>e mounted in the head for sweeping the symbol along a transverse

11(direction (Y-axis scanning) which is substantially orthogonal to ; .I

II ίi the predetermined direction. In some applications, multiple line scanning is preferred.

Referring again to FIGS. 1 and 2, the scanning mirror 44 is mounted in the light path of the incident beam at the rear region 18 of the head, and the motor 46 is operative for cyclically^ sweeping the incident beam through an angular distance A over a field of view across the bar code symbol located in the vicinity of the reference plane. A laser light-transmissive scan window 50 is mounted on the raised rear region 18, behind an opening 51 formed therein in close adjacent confronting relationship with the scanning mirror 44 thereat. As used throughout the specification and claims herein, the term close adjacent confronting relationship between components is defined to mean that one component is

I proximally located relative' to the other component, typically i .

i less than one inch apart of each other. As shown in FIG. 1, the i!

! scan window 50 is configured and positioned in the light path of the incident beam to permit the latter coming from the scanning mirror 44 to travel a distance of less than one inch within the :raised rear region 18, and then to pass through the scan window i !50, and thereupon to travel unobstructedly and exteriorly of and past the intermediate body region 20 and the front region 16 of the housing, and then to impinge on the symbol located at or near the reference plane.

The closer the scanning mirror 44 is. to the scan window 50, the larger will be the field of view of the swept incident ;beam for a given scan angle. It will be noted that the width i dimension of the scan window represents a limiting factor for the (sweep of the incident beam, because the housing walls bounding !

'!the scan window would clip aftd block any beam which was swept be! {

Ijyond the width of the scan window. Hence, as a rule, the scani!

i.ning mirror is made as close as possible to the scan window to

I ze the field of view of the swept incident beam.

!optimi

As best shown in FIG. 2, the field of view of the swept

.)incident beam is substantially independent of the width of the ;jbody portion 14 and, in fact, the field of view, i.e., the transAverse beam dimension, of the swept incident beam is actually h 4 ׳ • larger than the width of the body portion 14 at the front region I and at the forward section of the intermediate body region 20.

ל This is, of course, jdc־ ־ the fact that the swept incident beam

I .

• has been transmitted outside of the front and intermediate body

I regions of the housing. The side walls 15, 17 are not in the !light path and do not clip or block the swept incident beam.

!{The scan window 50 is mounted on the rear region 18 at an eleva;Lion above the top wall 11 to permit an overhead unobstructed il ^transmission. Ί i In a preferred embodiment, the width of the bodv portion 1^ is on the order of 1 3/4 inches, whereas the field of A view at the reference plane is on the order of 3 1/2 inches. In linrior art wide-bodied designs, the width of the housing was ״ &lt;

T !!greater than 3 1/2 inches in order to obtain a 3 1/2 inch^field :'of view for a given scan angle. Hence ,the exterior transmission

Hof the swept incident beam permits the head of the present in;i ijvention to have a narrow-bodied streamlined configuration. The ';‘.side walls 15, 17 need no longer diverge outwardly towards the ;!front as in prior art designs to accommodate the swept beam, but :׳can be made substantially parallel as shown, or in any other '.shape as desired.

In a preferred embodiment, the reference plane is 10ijcated about 2 inches from the front wall 19 of the head, and is ;!located a linear distance of .,;about 9 1/2 inches from the positive :;lens 30. The depth of field at the reference plane is about 2 3/4 Hon either side of the reference plane. These numerical figures are not intended to be self-limiting, but' are merely exemplary.

A laser light-transmissive non-scan window 52 is mounted j

Il . } ion the front wall 19 in close adjacent confronting relationship !

¹I ί (with the sensor means 54 located at the front region 16. The sen- J ii . .' |sor means 54 is operative for detecting the intensity of the light I i!_n the reflected beam coming from the symbol over a field of view | il .' across the same, and for generating an electrical analog signal ¹indicative of the detected light intensity. In order to increase . ¹׳I .!

!the zone of coverage of the sensor means, a pair of sensor elements’!

or photodiodes 54a. 54b are located on opposite sides of the longiiitudinal akis. The sensor elements lie in intersecting planes and ij !!face both forwardly and laterally. The front wall 19 is likewise ii )constituted of a pair of tapered wall portions 19a, 19b, each of which has an opening 53a, 53b formed therein. A pair of non'!Scan window portions 52a, 52b is fixedly mounted behind the open!Lngs 52a, 52b, respectively. Each non-scan window portion is l| ..

!mounted in close adjacent confronting relationship with its reIspective sensor element. The non-scan window portions are conii ־ ' !figured and positioned in the light path of the reflected beam jto permit the latter to pass therethrough to the sensor elejLents. Two small non-scan window portions are preferably utilized, 11 !irather than a single non-scan window, because two smaller windows i! j! . ., jare inherently stronger than one due to the greater perimeter that two windows provide.

The scan window 50 is located rearwardly of the non¹!scan window 52. Each window 50, 52 is located at a different i !‘distance- from the reference plane and the front wall 19. The !!

':scan window 50 is elevated above the non-scan window 52, as !described above. The non-scan window portions are located at !1 ;'opposite sides of the longitudinal axis. The scan window is i ן t ׳ :'located on the longitudinal axis.

;1

A printed circuit beard 59 is mounted within the body iii !1 u

¹.i. i : portion 14, and various electrical sub-circuits diagrammatically !

I represented by reference numerals 55, 56, 57, 58 are provided on : ! the board 59. Signal processing means 55 is operative to process ί i’ !1 the analog signal generated by the sensor elements to a digitized j signal to generate therefrom data descriptive of the bar code ן ' ! I! symbol. Suitable signal processing means for this purpose was , !described in U.S. 4,251,798. Sub-circuit 56 constitutes drive־ 'j circuitry for the scanner motor 46. Suitable motor drive circuitry i . . y.5. 4,min, .i for this purpose was described in ׳ - .i . ־' .. I j - . ... . -. .’ ־ .. Sub-circuits 57 and 58 constitute aj i safety circuit for the laser tube, and voltage regulator circuitry‘.

i: Suitable circuitry for this purpose were also described inן ii .ιμ,λ,μ. ..!

Shock mounting means are mounted at the front and rear ן i regions of the body portion, for shock mounting the laser, optical; •1 j i! and scanning components within the body portion. An annular shock.

!!collar 60, preferably of rubber material, surrounds the forward ;! end of the tube 22 and engages the bottom wall 13 and the under- j !1 1 !! side of the circuit board 59. Board support elements 61a, 61b ex-j tend downwardly of the top wall 11 to rigidly support the circuit j ί board 59. A pair of rubber shock mounts 62, 64 are fixedly mounted ! on opposite sides of the optical bench 24, and respectively engage! .j the side walls 15, 17 at the rear region 18 of the housing.' The I I! shock mounts 62 , 64 and the coll; r 60 are spaced longitudinally .ן apart of each other and engage the thin-walled housing at three j ׳ spaced locations to isolate twisting of the housing from the laser;, d optical and scanning components.

!11 j; Electrical power is supplied to the laser tube 22 by the !

^! power supply component to mounted within the handle portion 12.!

; The power supply component which steps up a l2׳vDC battery voltage | i'j to over 1 kilovolt is the heaviest component in the head, and its j !1;

il mounting in the handle portion allows for a low center of gravity . /1 ^! and for better balance of the head.J

A non-bulky, collapsible, coil-type cable 66 (see FIG. 6)1 electrically connects the head 10 to the remainder of the scanning.

!; system, which includes a battery-powered decode module 68 and a ־ H ** 1 ii host computer 70. The coil-type cable 66 is readily flexible and .

I permits user manipulation of the head 10 with multiple freedoms of; ! movement from one symbol to the next without requiring excessive ן j strength by the user. The cable 66 includes a plurality of con- j ί ductive wires which are all relatively thin and flexible. For ;

i !' example, one wire carries the 12vDC low voltage signal from the !

i battery in the decode module 68 to the power component ¢0. Another ! wire carries the digitized signal from the analog—to-digital signal j! ' . . ' ji processing circuitry 55 to the decode module 68 for decoding pur!!poses. This latter wire is non-radio-frequency-shielded, and

1. hence, is readilv flexible. The remaining wires carry low voltage.

ii ^- . i 'J control and communication signals. All of the wires of the cable ;

I 66 are connected together to a common plug-type connector 72. A | •' . ¹

I! mating connector 74 is mounted within the head, and receives the j |j connector 72 in a mating relationship. The use of the mating con-; ii i| nectors 72, 74 permits rapid replacement of the cable .or on-site . jl!

'i repairs. The electrical connections between the connector 74 and ;

' the various components in the head have been omitted from the j

I;

I ,־

I drawings for the sake of clarity.j

The decode module 68 processes the digitized signal cenerj; ated in the head, and calculates the desired data, e.g. the multiple h digit representation or code of the bar code symbol, in accordance';

j. i ¹I with an algorithm contained in a software program. The aecoae j i!j j module 68 includes a PROM for holding the control program, a RAM |

I ־I ί for temporary data storage, and a microprocessor which controls the i! PROM and RAM and does the desired calculations. The decode module';

;;( : also includes control circuitry for controlling the actuatable;

hj components in the head as described below, as well as two-way com-.

!! munications circuitry for communicating with the head and/or with i ! I X^-'.’ί ί! the host computer 70. The host computer 70 is essentially a large

H data base, and provides information for the decoded symbol. For !

example, the host computer can provide retail price information corresponding to the decoded symbols.

־

<img file="IL67034A_D0002.tif" />

— --A manually-actuatable trigger switch 76 is mounted on i the head in the region where the handle portion 12 is joined to ׳ the body portion 14. Depression of the trigger switch 76 is oper- ative to turn the microprocessor in the decode module on. Upon j

I release of the trigger switch, the spring 78 restores the switch !

i to its initial position, and the microprocessor is turned off. I

In turn, the microprocessor is electrically connected to the | actuatable components in the head via the cable 66 to actuate and | deactuate the actuatable components when the microprocessor is re-! spectively turned on or off by the trigger switch. j

In prior art heads, the trigger switch was only operative(׳/ to turn the laser tube and/or scanner motor on or off. Now, the j trigger switch turns the microprocessor on or off and, in turn, all of the actuatable components in the head on or off. The micro- I processor is a large power drain on the battery built into the decode module. Hence, by controlling the on-time of the microprocessor to j only those times when a symbol is being read, that is, when the !

trigger switch is depressed, the power drain is substantially ׳ | !

'j reduced, and the battery life substantially increased(over 5 hours).

1; ' !

Another feature of this invention is embodied in turning !

I _ !

j the microprocessor on or off by means of the host computer 70 which ! !

is remote from the head 10. The computer 70 typically includes ε ί j keyboard and a display. Once a user makes an entry on the keyboard, ! ' ; for example, by entering the identity of the code to be decoded, !

| the computer requests the microprocessor to turn itself on, store . J the information, and then to turn the microprocessor off. The !

&lt;I .i | microprocessor, again, is on only for so long as is necessary to ! ί

I comply with the computer request. The trigger switch and the key-; '1 1 .' h board computer entry are independently operable means for directly: Hi :I controlling the microprocessor, and for indirectly controlling the^; ii *j. רί

1( actuatable components in the׳ head.!

JI Another useful feature in having the microprocessor, I rather than the trigger switch, directly control the laser tube is to keep an accurate record of laser on-time for governmental recordkeeping. It is, of course, far easier to keep track of .-9Δlaser on-time in the software of a microprocessor than to!

manually record the laser on-time.:

j _־ | A set of visual indicators or lamps 80, 82, 84 is also ׳

I mounted on the circuit board 59, each lamp being positioned below i!

!ja corresponding opening in the top wall 11. The lamps are operaI

I tive to visually indicate to the user the status of the scanning :'!system. For example, lamp 80 illuminates whenever the laser tube ! j: ' I '1 is energized, thereby continuously advising the user whether the ן i!

!!tube is on or off. Lamp 82 illuminates when a successful decode has been obtained. It will be recalled that the incident beam is swept over a symbol at a rate of about 40 scans per second.

The reflected beam may be successfully decoded on the first scan, |or on any of the successive scans. Whenever a successful scan ii !has been obtained, the microprocessor will cause the lamp 82 to t .

i be illuminated to advise the user that the head is ready to read

I

I another symbol.

i

It is believed that the operation of the scanning system self-evident from the foregoing, but by way of brief review

H^is

I the gun-shaped head is grasped by its handle portion, and its barrel is aimed at the bar code symbol to be read. The sighting i! of the symbol is facilitated by the fact that the barrel is 11 !¹!narrow-bodied, and that there are no obstructions on the front .! and intermediate body regions of the barrel. The front wall of '!!the barrel is situated close to the symbol, it being understood

I that the symbol can be located anywhere in the depth of field at i

either side of the reference plane.

! The trigger switch is then depressed, thereby causing ! I ;!the microprocessor to erjergize the laser tube, the scanner motor,

-ו the sensor elements, and all the electronic circuitry provided : ו ;!on the printed circuit board..׳: The laser tube emits a beam, which

His then routed through the optic train as described above, and thereupon, the scanning mirror reflects the beam through the

5scan window and out of the head exteriorly of and past the front j and intermediate body regions of the body portion of the head. |

The reflected beam passes through the non-scan window portions to ;

I the sensor elements and is subsequently processed by the signal processing circuitry. The processed signal is conducted to the decode module for decoding. Once a successful decode has been realized, the microprocessor illuminates the lamp 82 and deactuates ! the head, and the user is now advised that the head is ready to 1 be aimed at another symbol. The flexibility of the coil-type cable facilitates the movement of the head to the next symbol. !

In addition, the movement of the head from one symbol to j the next is facilitated by the relatively low weight of the head. The head with all the aforementioned components therein weighs j i less than one pound. This represents a significant breakthrough l in the art of miniaturized and portable laser scanning heads. !

The twin-windowed head (the pair of non-scan window portions 52a, 52b constitutes one non-scan window 52; the scan ί

I window 50 constitutes the other window) with the rear, raised !

i scan window 50 overcomes several problems associated with the i prior art heads. To facilitate the explanation of these problems !

and how the twin-windowed head of this invention solves these problems, the top plan schematic views of FIGS. 7A, 7B, 7C, 7D ί have been provided. FIG. 7A diagrammatically illustrates a prior !1

Ί art wide-bodied head of the type shown in *the oromcnti-onee—eeJ ppndJ-ug .;!ppi! nnt ו nn U.——Ser No,—125 7-7-6-8-. FIGS. 7B and 7C i!

I¹, diagrammatically illustrate some head design alternatives, but ί

I which are unacceptable, because they fail to solve all of the ii prior art problems. FI(^. 7D diagrammatically illustrates the 'Inarrow-bodied, twin-windowed head of the present invention, as

II .

μ previously described in FIGS.!. 1-6.

;1 l| FIG. 7A shows an elongated body portion or barrel 86 !1 .i having a rear scanning means 44, 46, as described above, opera

:. tive to sweep an incident beam through a scan angle A of

<img file="IL67034A_D0003.tif" />

I predetermined arc length, e.g., 25°, through a single front win- י dow 92. The reflected beam also passes through the front window | ![92 to be detected by the sensor elements 54a, 54b, also described ׳, I !

!above. The barrel is relatively wide-bodied to accommodate the ! !1i

II

I swept incident beam within the barrel, and the front of the hous• ing is relatively close to the״reference plane.

!! As compared to FIG. 7A, FIG. 7B shows a narrower barrel p88 having a more forwardly scanning means 44, 46 operative forן

I sweeping the incident beam through a larger scan angle B, e.g.ן i on the order of 45°, through a single front window 94. The re- !

I fleeted beam also passes through the front window to be detected ! |l _£ , . , .!

! by the sensor elements 54a, 54b. The front of the housing is ; ! spaced further from the reference plane.ΐ

I ίί As compared to FIG. 7B, the scanning means 44, 46 in

-ו ו ן;FIG. 7C is located near the middle of the barrel 90, and is operaj|tive to sweep the incident bean through the original 25° scan ':'angle through the single front window 96. The reflected beam !i ;(also passes through the front window for detectio¹'. by the sensor i I !!.elements 54a, 54b. The front of the housing is spaced much furthe: !1 lifranthe reference plane.

• FIG. 7D needs no detailed description, except to repeat

I

I that the rear scanning means 44, 46 has its scan window 5.0:.rear!1 ! wardly located on the housing. The scan window 50 is raisea so that the swept incident beam is not accommodated within the barrel

14. The reflected beam passes through a different window, i.e., ! the non-scan window 52 located at the front of the barrel.

!! In rating the performance of a laser scanning head, !;the spot speed variation of the scan across the symbol should i I ;!ideally be constant so that -t£e signal processing circuitry can ibe simple, i.e., without requiring sophisticated circuitry to π

<img file="IL67034A_D0004.tif" />

/compensate for the spot speed variation. By way of example, the ; !!spot speed at point X in the depth of field C is much greater thanj iithe spot speed at point Y. It is well known that the lower the i η j !! scan angle A, the lower will be the projected spot speedj /variation. Hence, a 25° scan angle as illustrated in FIGS. 7Ά, 7C,; ' i o>

ji 7D is better in terms of spot speed variation than the 45 scan . j angle of FIG. 7B.i

I As noted above, the problem of dirt specks on the j ! . . . !

I scan or exit window adversely affects the scanning ability,;

jl particularly where the window is positioned in the light path!

where the scan spot is focused and relatively small. Hence, the ׳ Greater the spot size and concomitantly the greater the distance ׳, between the exit window and the reference plane, the better the !

I ! scanning performance. Hence, the head of FIG. 7D with its rear ; !! exit window 50 the furthest from the reference plane has the

II : -ו least sensitivity to dirt specks, and the heads of FIGS. 7C, 7B, ii-!

l| 7A are successively more sensitive to dirt specks.j ί In terms of light sensor effectiveness, the closer ־, ;! the sensor elements are to the referehce plane, the more sensitive

1! will be the detection by the sensor elements. Hence, the heads

: .1׳

H of FIGS. 7D and 7A have the best light sensitivity; the head of !' FIG. 7B has less light sensitivity; and the head of FIG. 7C has 1 I ! I jl the worst light sensitivity.

!' In operation, it is easier for a user to gauge j a working distance close to the head, rather.than a working j distance located far therefrom. Typically, it is easier for i the user to aim the head at a symbol located, for example, anyi!

jl where between 1/4 and'^6 away from the front wall 04. the barrel, j| rather than aim the head at a symbol located, for example, / between 9 and 12 from the;ifront wall. Hence, the heads of H FIGS. 7D and 7A are the best in terms of user convenience; the J head of FIG. 7B is less convenient; and the head of FIG. 7C is the most inconvenient.

Of great importance is the effect ׳ I ¹!!width has on the width of the scan. As shown that the barrel in FIG. 7A, the entire width of the scan must be accommodated in the barrel 86, thereby resulting in a wide-bodied, unaesthetic design. If the scanner means is moved forwardly as shown in FIG. 7B so as to the barrel, then the scan angle must be narrow the width of increased to obtain the same field of view. As noted above, ;! increasing the scan angle is not an acceptable solution, because ji it worsens the spot speed variation performance. If the scanner

I means is moved rearwardly back towards the middle of the barrel and the scan angle is kept at its original arc length, and the body is kept harrow, as shown in FIG. 7C, then the light sensor effectiveness will worsen, and the convenient judgment of scan distance will worsen.

In a non-retro-reflective mode, the applicants have recognized that the use of a single front window through which the incident and reflected beams must pass has conflicting requirements. By providing a rear window and a front window for the beams, these conflicting requirements are resolved.

The head of FIG. 7D has the best insensitivity to dirt specks on the exit window, has the narrowest barrel width, and has optimum over spot speed variation, optimum ease of judging scan control distance and optimum light sensor effectiveness.

In accordance with the invention, the housing need only be large enough to accommodate the components. This benefits styling, cost and weight. The scan width may be varied from one application to the next without making a change in the barrel.

By mounting the scanning means close to the rear scan window, the field of view of the incident beam wide. Analogously, is made very by mounting the sensor means, close the field of view of the reflected to the front beam is made non-scan window very wide. Furthermore, the close mounting of the scanning and sensor means to

י !

־־־ז ΐ their respective windows, eliminates the prior art narrow slit j aperture, and eases optical alignment of the incident beam, andj avoids potential clipping of the incident beam if the beam angle j !!drifts.I ΐi

I Referring now to FIGS. 8 and 9, the gun-shaped head I

100 is essentially analogous to the head 10, except as noted jbelow. Hence,any like components in FIGS. 8 and 9 have been !!identified with the same reference numerals as were used prevjl.

iiously. Rather than a laser tube, a semiconductor laser diode

I1 '1 102 is mounted within the barrel 14 to generate an incidentj

I’ ¹I !!laser beairi. Rather than a folded path optical train_t an optics tube 104 is axially aligned with the laser diode. A lightreflecting mirror 106 is adjustably mounted on a bendable bracket ';108 that is mounted on the exterior of the tube 104. The mirror i!

j;106 is positioned in the light path of the incident beam to di!1 j rect the incident beam towards the scanning mirror 44 of the jscanner motor 46. As described previously, the motor 46 is !operative to sweep the incident beam through the rear scan window !50 and outside of the barrel 14 past the intermediate body region 1*20 and front region 16 thereof. The reflected beam passes !through the non-scan window 52 to the sensor means 54 for de.tection and subsequent processing as previously described.

A keyboard 110 and a display 112 are mounted on the top wall 11 of the barrel. The keyboard 110 comprises a plurality !: i!of manually-depressable keys, each for a different numeral, and ¹¹ , _ ||a set of function kevs to calculate and display various !unc!1 ' ¹i'tions reauired in a givqn application. The display 112 may be of ;!

Ilow power LCD type.By mounting the display 112 and the keyboard i

[110 on the head 100, this feature facilitates keyboard entry and !;data reading at the site of the symbol to be read, rather than at a more remote location away from the head.

;; Inasmuch as the laser diode 102 does not require a '!voltage step-up component 40, but can be energized directly from J !ia low voltage battery, a battery 114 is mounted within the handle to energize the diode. In order to even further facilitate the ΊI ף movement of the head 100 relative to the remainder of the system, ; 11i &lt;! the aforementioned cable 66 is totally eliminated. In its place, !

'j a transmitting antenna 116 may be ־mounted’at the :rear of the handle,. ן and is operative to electromagnetically transmit the processedן

I information to the remainder of the system. In addition to circuit -ו board 59, another circuit board 118 is provided within the barrel !

Iו

I to accommodate the additional electronic circuitry for the keyboard

Ii j and the display.!

I!

j Still another circuit board 120 is mounted within the ן

I barrel to accommodate a radio transmitter 124 and a frequency:

I shift key modulator 125. The modulator 125 will place one orj ;:another tone (frequency )on the radio wave generated by the trans- ן !1 mitter 124 and telemetered over the antenna 116. In one embodi- ί

1I !1 iment of the invention, the telemetered signal corresponds to the I I!

!! digitized signal generated in the head, and the telemetered signal' ii '!

il is received by a receiver and a demodulator, which are incorporated i!i !’ in the decode module 68. In this case, the decode module 68 must : 1!1 ;1 J

I

I

I

I

ח !1 also have a return transmitter and a modulator for electromagnet!-! cally telemetering the decoded information back to the head*100,’ where the decoded information is then received and demodulated by I

I a return receiver 126 and a demodulator 127, which are also mounted on circuit board 120. The decoded information can be displayed on display 112.

In another embodiment of the invention, the entire decode! j !

module 68 may be reduced by large scale integration to one or two I integrated circuit chips, e.g. chips 128, 129, which are mounted | on yet another printed circuit, board 122 provided in the barrel. I i In this case, the digitized signal generated by sub-circuit 55 is ׳ decoded by chips 128, 129 right in the head 100, rather than at some location remote from the head. Hence, the telemetered signal ; corresponds to the decoded signal generated in the head, and the ir telemetered signal is transmitted not to a remote decode module, but directly to the host computer 70, which must now include a receiver and a demodulator for the decoded signal. Of course, the host computer must also include a return transmitter and a modulator for electromagnetically tele• metering the desired data back to the head 100, where the data is then received and demodulated by the return receiver 126 and the demodulator 127. The data can be displayed on display 112.

The laser scanning head 100 shown in FIGS. 8 and 9 constitutes a complete and independent data processing workstation in the sense that it is fully portable; it is battery-powered; it decodes the symbol in the head; and it is not mechanically connected to any remote system component. The head 100 is readily adaptable to interact with any host computer.

As noted previously, the host computer or terminal 70 is a data base, and may be incorporated in a built-in large computer installation; or can be made smaller and constitute a light-weight, hand-held, discrete unit; or, as shown in FIGS. 8 and 9, can constitute an integrated circuit storage 129' and be mounted within the head 100 on board 122 to form a complete data collection terminal which facilitates real-time and subsequent data processing at the site of the symbol to be read. As described above, the interconnection between the module 68 and computer 70 can be hand-wired, or by means of telemetry, or by plug-in connection, or by electrical circuit connection in the head.

a- ii !1 !1

- --------- ' ווי- ו׳ ί! Referring now to FIGS. 10 and 11, reference !י numeral 130 generally identifies a gun-shaped, laserless, jj

I! twin-windowed head analogous to the previous heads 10, 100, i| .

!! except as noted below. To simplify the description o_ ii head 130, like parts previously described in connection with the earlier embodiments have been identified with like reference numerals. One major distinction of the

I _t ί head 130 is that the incident beam is not swept, but is i transmitted from the front of the housing, and that. it is i| the reflected beam that is swept over its field of view.

: Put another way, the sensor means sweeps across the symbol.

!1 It is the reflected beam that unobstructedly travels

1' exteriorly of and past the front and intermediate body regions i; of the housing.

ί Rather than a laser tube or laser diode, the laserless

I head 130 comprises a light source 132 which includes a pair ;| of light source elements 132a, 132b at opposite sides 01 the |j longitudinal axis, each light source element facing both

B forwardly, upwardly and laterally to emit a light beam. Again, |! the light source elements need not generate a laser beam !ן but are operative to generate any type of light beam, ana may !i i| constitute high-powered LED's (30-100mW) or a miniature || quartz halogen bulb. The incident light beam passes through || a light-transmissive front non-scan window 152 located at !j jj the front region 16 of the body portion 20 of the ! Ύ i!

bhead in close adjacent confronting relationship with the light source elements 132a, 132b thereat. In a variant from non-scan window 52, the non-scan window 152 is a wrap-around window which i

I extends transversely along the front wall and also partially along i

I the side walls of the head. After passing through the non-scan window 152, the incident beam illuminates the symbol. It is preferable if the incident beam is directed slightly upwardly, such that the reflected beam will be directed, as shown, that is, exteriorly of and past the front region 16 and intermediate body

ן i

ί i

I

I

I

I i

I i

recion 20 above the top wall of the body portion. The reflected beam passes through the raised rear scan window 150 and impinges !

I on the scanning mirror 44 which is being repetitively oscillated | by the scanner motor 46 to scan the field of view of the reflected!

beam across the symbol. The swept reflected beam is thereupon directed towards the light-reflecting mirror 134 which is adjustably mounted on a bendable mounting bracket 136 on a sensor optic tube 138. The mirror 134 is positioned in the light path of the reflected beam to direct the reflected light off the mirrorj j through the sensor optics tube 138 to the sensor means 140 I ;mounted within the body portion 14 at the rear region 18 of the I

I . j !head.

j As best shown in FIG. 11, the reflected light beam is

I i swept over a transverse beam dimension which is larger than the width of the body portion. Hence, here again,, the field of view of the swept reflected beam is substantially independent of the barrel width.

1| ¹;I Referring now^to FIGS. 12 through 14, reference numeral j! 160 generally identifies a gun-shaped, single-windowed, laser ίι scanning head arranged for r^tro-reflective scanning. As before, I! to simplify the description, like parts previously described have !1 !been assigned the same numerals as before. The head 160 comprises | !a laser light source, e.g. a semiconductor laser diode 162,| ^,^operative for generating a laser light beam, and for directing the : !!same through an optical train including the positive lens 164 and ’ ii :the light-reflecting mirror 166 adjustably mounted on a bendable ; I!

!^,;bracket 168 which is, in turn, mounted on an optical bench 170. I| ! The mirror 166 is positioned in the light path of the incident beam to direct the same from the lens 164 towards and through an aperture 172 centrally formed in the sensor mirror 174. The incident beam travels unobstructedly through the aperture 172 and

I impinges on the scanning mirror 44 of the scanner mirror 46. The ;

I scanning mirror 44 directs the incident beam through the raised j !1 !

1. rear light-transmissive window 176 and out over an intermediate '11 body region 20 and the front region 16 of the head. The motor 1;

' 46 is operative to sweep the incident beam over a transverse beam ;

iI

I dimension which, in variance with the previous embodiments, is I i .[ >I !i less than the width of the barrel 14. The exterior transmission (

¹ן • ||of the swept incident beam causes the transverse beam dimension ' i ^A

I to be substantially independent of the barrel width. The lack o!!

ίί a direct relationship between the size of the swept incident beamJ j and the barrel width includes the possibility that the transverse| i beam^di^ension may be greater or smaller than the barrel width.I ί י' i Of course, if desired, the incident beam may be swert over a j ίI field of view larger than the barrel width. ..j • Likewise,the reflected beam travels outside of and i past the front and intermediate body regions and passes through !1

1' the same raised rear window 176 for impingement on the scanning : mirror 44. [ i The scanner motor',44 also sweeps the field of view of I |i bty&amp;W !

H the reflected beam over a transverse beam dimension which is less,׳ /1 \ but which could be greater, than the barrel width. The sensor ! mirror 174 is positioned in the light path of the reflected beam ! such that the light-reflecting portions of the mirror 174 bounding ; the aperture 172 reflect the reflected beam rearwardly towards the sensor convex lens 180 and, in turn, to the light sensor element 182. The lens 180 and the sensor element 182 are both mounted on respective brackets 184, 186 on the optical bench 170,

It will be noted that only a single raised rear window 176 is mounted on the head 160. No front window is necessary as in previous embodiments of the heads 10, 100, 130. Both the ;incident and reflected beams are swept and travel through the same i raised rear window 176. Here again, the fields of view of both jthe swept incident and reflected beams are substantially independ ent of the barrel width.

Turning now to the field-replaceable laser tube arrangement shown in FIG. 15, this arrangement can be used to quickly and (easily replace the previously mentioned laser tube 22 mounted in '1 ' a laser-scanning head. As described earlier, the tube 22 has an output end 23 and a non-output end 25. The optical bench 24 has an enlarged recess 35 concentric with a bore 25. An electrically conductive metal washer 36 is mounted in the base of the recess

135. A metal cylindrical support sleeve 34 closely surrounds the !.tube,and the diameter of the sleeve closely matches the diameter

I of recess 35. The output end 23 has a machined cylindrical

I i i !

shoulder 23a which is known to be concentric with the output laser beam. The diameter of shoulder 23a closely matches the diameter of bore 25. Tlfe shoulder 23a makes an electro-

ץ j mechanical, non-soldered contact with the washer 36. A high i voltage power wire 200 extends through a transverse bore in the

H bench 24, and is soldered to the washer 36.

!i

At the non-output end 25, a machined shoulder 25a surrounded and engaged in force-transmitting, electrically is !conductive relationship with one end of a biasing means, i.e. elonaated coiled spring 202. The other end of spring 202 engages ] a removable electrically-conductive locking cap 204 which is, j in turn, detachably mounted on a stationary support wall 206 of ¹ the head. A ground wire 208 is soldered to the cap 204.

When installed as shown in FIG. 15, the spring 202 is under compression, and is operative to constantly urge the tube forwardly so as to bias the machined shoulder 23a into ilaffirmative electro-mechanical contact with the washer 36. It I should be noted that the spring 202 is the functional equivalent i of the taut wire 38 described in connection with the embodiment ן '1 of FIGS. 1-6. j

In order to replace a used tube with a fresh one, the j I removable cap 204 is detached from the wall 206, thereby permitting the tensioned spring 202 to be removed. The used tube 22 can now ; be slid out of the sleeve 34, and the fresh tube inserted. The !

. I .spring is then re-mounted on the non-output end 25, and the cap is I replaced to the illustrated position

It will be noted that no soldering or unsoldering .

operations are required to remove the used tube or to install a ! fresh tube. The power wires 200, 208 are not connected to the tube ends, but instead are permanently connected to the components i 36 204. As noted above, this is in contrast to prior art laser

I

I tube-based scanning heads, where the power wires are directly ‘1 connected to the tube eiids.

1׳ It will further be noted that the laser tube 22, once |!

j installed, is automatically*Optically aligned with the optic

I means, e.g. convex lens 210. Hence, in contrast to prior art j ־ - ־ ־ . - --------- -i

I heads, no skilled personnel are required to align the output ! ii

I beam to the optic means.j j The presence of a convex lens 210, rather than a;

Iii j concave lens, immediately at the output end of the laser tube ; ׳I • 22 represents yet another significant breakthrough in the art . !!

I| of laser scanning heads because, as will be demonstrated ini

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I] connection with FIGS. 16 and 17, the present invention alsoן

1' ’I p includes a novel laser tube having a diverging, rather than the j ! usual collimated, beam, as well as a method of making such i!

j a laser tube.

| Before discussing FIGS. 16 and 17, it should be noted

II

I that in many types of lasers, a concave mirror is placed at | ן one end region within the tube, and a substantially flat or j piano-type mirror is placed within the tube at its opposite !

1! end region. It is well known that the wave-fronts at the mirror H '!

!ן are the same shape as the latter, and that the wave-fronts are >

i flat at a beam waist. Hence, the wave-front at the flatI

I ί mirror is likewise .flat, and there is_ a beam waist there. The | wave-front at the concave mirror is likewise concave. Typically,;

!1 the inner surface of the flat mirror is coated with a coating ! >i which has a high predetermined reflectivity, e.g. on the order ; Ί. i j! of 100% maximum reflectivity, so that ideally, no transmission, I ף except for unavoidable leakage, occurs through the flat mirror. | ;; Also, the inner surface of the concave mirror is typically!

iiI

I: coated with a coatin□ having a reflectivity less than said high j 'i 'I predetermined reflectivity, e.g. on the order of 99% reflectivity^ so that about 1% of the beam is transmitted through the concave ! i ii mirror. Hence, the output end of the tube is located adjacent I i| the concave mirror.J

However, in the prior art lasers, the outer surface of ;

the concave mirror is ground to just the right radius of curvature !1

Η i;

ί! -

I so as to flatten the wave-fronts at the concave mirror in order to produce a flat wave-front and another beam waist at the ground :!outer surface of the concave mirror. The beam waist at the ::concave mirror has a larger diameter than at any other point • within the laser between the mirrors, and is much greater than ! the beam waist at the flat mirror. In the field of laser !

j scanners, the larger output beam at the concave mirror is very ' desirable, because it provides the smallest beam divergence. j'jHence, in this field, the output laser beam is always collimated, j!

}ןi.e. substantially parallel, and is always taken from the end !!

''!adjacent the corrected concave mirror.

j| In contrast, the present invention proposes modifying |1 .!the laser tube so that the output beam diverges. In one embodiil i'ment, the diverging output beam is taken from the end adjacent ii ..

;the concave mirror. In another embodiment, the diverging output j beam is taken from the end adjacent the flat mirror.

I Referrina now to FIG. 16, the tube 22 has a flat mirror ! ! ' . - I j! 212 adjacent non-output end 25, and a concave mirror 214 adjacent ; ’1 ¹J output end 23. The inner surface, of flat mirror 212 has a !

’!coating 216 with ii l| described above.

j i |j coating 218 with the high predetermined reflectivity characteristics

The inner surface of concave mirror 214 has a | the lower reflectivity characteristics described )

I above. The inner coated surfaces of the mirrors face each other. |

I

In accordance with one aspect of this invention, the outerj surface 220 of the concave mirror 214 is ground to have a curvature •i ' which is weak, optically speaking, in order to increase the!

I

I already divergent characteristic of the concave mirror. In a | ijpreferred embodiment, the outer surface is ground to provide an !

I angle of divergence in the range of about 10 to about 100 i ׳

J milliradians. !

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I Referring now to FIG. 17, like parts have been assignee !

I like reference numerals. It should be noted that the coatings ן

I on the mirrors have been reversed such that the higher reflectiv- ן ! ity coating 218 is now provided on the inner surface of the flat . I! mirror 212, whereas the lower reflectivity coating 216 is now ־ ;i provided at the inner surface of the concave mirror 214. Since ;

!! the light beam passing through the flat mirror 212 is smallest at jj the latter,the far-field divergence of the beam is as large as ^!| possible due to the diffraction effect. The angle of divergence I! . . .

:j achieved by relying solely on the diffraction effect is on the h . .

II order of 3 milliradians, which is not useful in all scanner head !

J! applications. Hence, in order to increase the angle of i'| ’־ .

j divergence, the outer surface 222 of the flat mirror 212 is j ground to have a curvature such as to diverge the beam to the i

I il

II i,׳ ח • I !1

ף required extent. The divergent output beam is emitted through the output end 23 adjacent the flat mirror 212.

In both cases, the modified laser bean diverges. It will be recalled that in the typical optical system used in the laser scanning head, a negative lens is used to diverge the beam, and a positive lens is used to focus the beam to the spot size and location desired. With the divergent laser output of this invention, the negative lens and its attendant size, weight and cost are eliminated. Returning then to FIG. 15, it will be noted that the negative lens has been totally eliminated, and only the positive lens 210 is located adjacent the output end 23 of the tube.

p It will be understood that each of the elements i!

H described above, or twe^or more together, may also find a useful

Ij ! application in other types of constructions differing from the |j types described above. /' !1 :1

־38־ close-in symbols will be reduced, thereby flattening the :

i amplitude variation and increasing the depth of field. .

i

Still another way of optically increasing the depth :

of field by decreasing the amplitude variation is to constitute ' the window associated with the sensor means as a narrow spectral ; band interference filter (6328S), or to mount a discretei interference filter at either side of the window. The filter ׳ f is operative to suppress ambient light and to attenuate theI amplitude associated with close-in symbols, thereby enhancing ' t the dynamic range.>

Yet another way of optically increasing the depth ofj field by decreasing the amplitude variation is to mount thej sensor means at the rear region of the housing. As shown in 1 ! ’I !FIGS. 9 and 10, the sensor means 140 is located at the rear !of the housing, and the amplitude variation for far-out and close-in symbols for the aforementioned case where the depth of field is desired to range from about 1/2 to about 6 is reduced from about 100:1 to about 4:1 without the necessity of | providing for a fresnel lens window or complex signal processing

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The retro-reflective embodiment of FIGS. 12-14 is highly advantageous on the matter of signal to noise ratio,!

! and this embodiment together with the increased depth of field.;

i feature described above constitute a very efficient laser|

I scanning head.:

I Another advantageous feature relating to increasing the i |! signal to noise ratio lies in synchronous detection. The‘ ! laser diodes 102 (FIG. 8) and 162 (FIG. 13) and the light source I I elements 132a, 132b (FIG. 11) are well suited to be pulsed at some; I -.:i i! predetermined frequency, and' the sensor means includes narrow- j .1 band amplifiers tuned to said pulsed frequency. Hence, / the signal to noise ratio is greatly increased.

d11 For example, the trigger switches 76, 76' respectively !!shown in FIGS. 1 and 8 are both operative to depress the spring 78r ¹ i however, switch 76 is provided with a safety overload feature. A '!groove 75 is formed at the rear of the trigger 76 and forms a user-:

'1'i :engaging trigger portion 77 and a switch-actuating trigger portion ;

:1:

;!79. A guide finger 71 on the trigger extends into a guide aperture J !!formed in a front abutment portion 73 on the handle 12. In use, a jluser depresses the user - engaging portion 77, and causes the I Ii switch-actuating portion 79 to pivot and depress the spring 78.;

However, in the event that the user depresses the user-engaging portion 77 too forcefully, i.e. beyond a predetermined safety load;

i limit, the user-engaging portion 77 will slightly bend or flex relί ative to the switch-actuating portion 79 due to the slight struc- ‘ ' tural weakness caused by the presence of the groove 75. This fea- :

i I ture safeguards the spring 78 and the circuit board on which the !spring 78 is mounted, and protects the spring 78 and *board from being damaged due to an excessive load on

I switch. The predetermined safety load limit for the 1!

'!determined beforehand, and the user-engaging portion its circuit j the trigger i trigger is j 77 only flexes ;!if this limit is exceeded.

As a further safety feature, the user-:

!!engaging portion 77 is permitted to flex only until the latter !

I abuts against the front abutment portion 73 which effectively pre- ;

! vents any further rearward movement of the trigger.I

Another useful construction relates to increasing the i ! depth of field, i.e. the working distance, of the laser scanning;

¹;!head. It will be recalled that a bar code symbol can be read at;

'!either side of the reference plane, and the range in which the 11 ..

;'symbol is read is defined as the depth of field. For convenience,; ha symbol that is located between the reference plane and the head : ! , . ' :!is defined as a close-in symbol, whereas a symbol that is located ;!on the other side of the reference plane away from the head is defined as a far-out symbol.

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As noted above, the sensor means detects the light inten- !

sity of the reflected light beam, and generates an electrical ן signal indicative of the detected light intensity. This i electrical signal is then processed by the signal processing | means. Inasmuch as the amplitude of the reflected light, י and hence the amplitude of the generated electrical signal, is | a function of the distance at which the symbol is located relative i to the sensor means in the head, laser scanning system designs j

I should take into account the variation in amplitude which occurs ן

I for close-in and far-out symbols. For example, in a case where the depth of field ranges from about 1/2 to about 6, and where the reference plane is on the order of 4' from the sensor means, then the amplitude variation at the opposite ends of the range can be on the order of 100:1. This amplitude variation is undesirably high, but could be electrically compensated for in the electronic signal processing circuitry.

However, the required electronic circuitry is highly complex and expensive, thereby relegating the laser scanning system designer to be satisfied with a much smaller depth of field, i'i rather than include the complex electronic circuitry.

I; In accordance with the invention, passive optical means il ‘j are provided for decreasing the afore mentioned amplitude

H variation, particularly by reducing the amplitude associated l| with a close-in symbol without the addition of the complex i| electronics. In a preferred embodiment, the aforementioned window associated with the sensor ineans, i.e. non-scan window or scan windows 150Λ176, rather than constituting a mere

1: window with no light-modifying properties, may be replaced ׳i ., ; by a positive lens such as a'fresnel lens. The fresnel lens i!

'! window has a height larqer than that of the sensor means, i.e.

the photo-detectors.For far-out symbols, the fresnel lens window

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I I t I i __ ______ - . . - - j i directs virtually all the returning rays of the reflectedj

I light beam to the photo-detectors. This boosts the!

i signal strength associated with the far-out symbol. For!

i close-in symbols, only a portion of the returning rays of:

the reflected light beam is focused by the fresnel lens window t on the photo-detectors, thereby decreasing the signal strength | associated with the close-in symbol. ן k Hence, the fresnel lens window is optically operative ; not only to reduce the amplitude associated with a close-in.

symbol, but also to increase the amplitude associated withj a far-out symbol. In the aforementioned case where the depth of field ranges from about 1/2 to about 6 from the sensor means; the fresnel lens window changes the amplitude variation from;

about 100:1 to about 5:1. This reduced dynamic range is well!

within the capabilities of the electronics of the signal' processina means, which now need not be designed with complexI electronic signal processing circuitry to account for high.

amplitude variation. The depth of field has been increased without the need for such additional complex electronic circuitry.'

Rather than a fresnel lens window, another passive;

»i

I optical light-modifier means such as a stationary louver con- !

ן figurated like a Venetian blind with mutually parallel permanent- 1 !'. . ! ly-ooen slats could be mounted at the front region of the housing,.

either forwardly or rearwardly of the window associated with | { the sensor means. The closer the symbol is to the sensor means, | i the more light is blocked by the louver. When the symbol isj j ' . '£j | distant, more light will pass through the louver to the sensor j !! means. Alternatively, an overhead visor or shade could be!

'!I .i mounted forwardly of the sensor means. As the symbol comes ! i j closer to the sensor means, the visor blocks more and more light .: from the sensor means. In both cases, the reflected light beam is optically modified and the amplitude associated with c-__

While the invention has been illustrated and described as embodied in a narrow-bodied, single-and twin-windowed, portable laser scanning head for reading bar code symbols, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this _;invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.