Flash socket assembly

[57] ABSTRACT

A flash socket assembly for use in or with a photographic camera is constructed to receive a multilamp flash assembly having at least one array of lamps facing in a common direction and a thin, shallow connector blade adapted to be inserted into the socket assembly. An electronic flash selecting circuit, preferably fabricated as an integrated circuit chip, selects one or more of the lamps for ignition in accordance with a predetermined selection program when a firing command is received. The socket assembly includes circuit support means for providing structural support for the flash selecting circuit and protection for the integrated circuit chip, and for facilitating handling of the socket assembly during fabrication thereof and during assembly into an associated photographic camera.

Claims, 15 Drawing Figures

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ΡΑΤΕΝΪΕ0ΜΠΙ973

3,745,895

SHEET 1 OF 5

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FIGI

INVENTORS

BY

EDISON R. BRANDT JAMES K. SKURSKI

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ATTORNEYS

PATENTED >171973

3.745,895

SHEET 2 OF 5

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EDISON R. BRANDT JAMES K. SKURSKI

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ATTORNEYS

PATENTED JUL 171973 3,745,895

SHEET 3 OF 5

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<img file="US3745895A_D0007.tif" />

<img file="US3745895A_D0008.tif" />

ATTORNEYS

PATENTED Μ171973

3.745,895

SHEET U OF 5

<img file="US3745895A_D0009.tif" />

<img file="US3745895A_D0010.tif" />

<img file="US3745895A_D0011.tif" />

INVENTORS

EDISON R. BRANDT JAMES K. SKURSKI

<img file="US3745895A_D0012.tif" />

ATTORNEYS

PATENTED > 171973

3.745,895

SHEET S OF 5

<img file="US3745895A_D0013.tif" />

FIG. 13

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INVENTORS

EDISON R. BRANDT JAMES K. SKURSKI BY

ATTORNEYS

3,745,895

It is an object of this invention to provide for use in a photographic flash illumination system employing a multilamp flash assembly and in an associated photographic camera a static electronic flash selecting cir5 cuit, means for supporting and protecting the flash selecting circuit and associated interconnections.

It is another object of this invention to provide as part of such a photographic flash illumination system, an improved socket assembly having as a part thereof 10 means for supporting and protecting a static electronic flash selecting circuit and for providing means for holding and manipulating the socket assembly during assembly thereof.

It is yet another object to provide means for support15 ing and protecting a flash selecting circuit fabricated as an integrated circuit chip, and in particular to provide means for mechanically shielding the chip against physical damage during handling of the socket assembly.

Further objects and advantages of the invention will 20 in part be obvious and will in part become apparent as the following description proceeds. The features of novelty which characterize the invention will be pointed out with particularlity in the claims annexed to and forming a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the front portion of a photographic camera embodying a flash illumination system including a flash socket assembly implementing 30 the teachings of this invention; a multilamp flash assembly adapted for connection into the socket assembly is shown exploded from the socket assembly for clarity of illustration;

FIG. 2 is a schematic view of a flash illumination sys³⁵ tem with which this invention is concerned;

FIG. 3 is a perpsective view of a flash socket assembly incorporating the teachings of this invention;

FIG. 4 is a bottom view of the FIG. 3 socket assembly;

⁴θ FIG. 5 is a bottom view of the FIGS. 3-4 socket assembly similar to FIG. 4 but showing a printed circuit strip pulled back to reveal the underside of the socket body;

FIG. 6 is a side elevational view of the FIGS. 3-5 4$ socket assembly, partially broken away;

FIG. 7 is a fragmentary perspective sectional view of the socket assembly shown in FIG. 3 as it would appear with the connector blade of a flash assembly inserted into the socket assembly;

⁵⁰ FIG. 8 is a fragmentary sectional view taken generally along lines 8—8 in FIG. 3 as it would appear empty and with the contact members cut away;

FIG. 9 is a fragmentary sectional view taken generally along lines 9—9 in FIG. 3;

⁵⁵ FIG. 10 is a fragmentary sectional view taken generally along lines 10—10 in FIG. 3 showing the socket assembly as it would appear when empty;

FIG. 11 is a view similar to FIG. 10 but showing the contact members as they would appear when a flash as° sembly is: connected in the socket assembly; and

FIGS. 12-15 are views illustrated an alternative embodiment of the invention; FIGS. 12, 14, and 15 are views corresponding to FIGS. 7,10, and 11; FIG. 13 is a fragmentary top view of the socket assembly.

FIG. 1 illustrates a flash assembly 10 of a type and construction as shown and described in the abovenoted U.S. Pat Nos. 3,598,984 and 3,598,985. The

FLASH SOCKET ASSEMBLY

BACKGROUND OF THE DISCLOSURE

A new generation of photographic cameras has been revealed by the assignee of this application in recently issued patents, including U.S. Pat. Nos. 3,447,437; 3,543,662; 3,561,339; and 3,587,426. These patents disclose advanced folding cameras having an extremely high degree of compactness when in their folded state.

This invention concerns, in general, certain aspects of a novel flash illumination system having broad application but intended especially for use in or with such advanced cameras. The system utilizes as its source of luminous energy a disposable multilamp flash assembly having at least one, but preferably two, arrays of lamps of common orientation, as shown and described, for example, in U.S. Pat. Nos. 3,598,984 and 3,598,985. In this flash illumination system, the flash assembly is interfaced with a flash selecting system which selects the flash lamp or lamps to be fired when a firing command is received. The flash selecting system is preferably a static electronic flash selecting circuit as shown, for example, in U.S. Pat. No. 3,618,492, assigned to the assignee of this invention.

As shown in the referent U.S. Pat. Nos. 3,598,984 and 3,598,985, the multilamp flash assembly includes a support structure from which extends a shallow, thin connector blade carrying a set of electrical terminals for the lamps. The flash assembly has two back-to-back arrays of lamps having respective sets of terminal strips disposed on opposite sides of the connector blade. The arrays are used in sequence by first igniting the lamps in one array, then disconnecting the flash assembly from the associated flash socket, reversing the orientation of the assembly, and reconnecting the assembly in the flash socket.

In a preferred embodiment the above-described flash selecting system contains logic elements fabricated in an integrated circuit (I.C.) “chip.” Electrical interfacing of the flash selecting logic in the chip with the lamp terminals on a multilamp flash assembly is accomplished in a novel flash socket assembly containing a plurality of contact members supported to register with and engage lamp terminals on the connector blade of a flash assembly inserted into the socket assembly.

In a preferred structure the leads from the chip are connected to the contact members in the socket by conductors printed on a flexible substrate.

The electrical interfacing structures are, however, susceptible to damage during handling of the socket assembly, particularly the chip and its terminals, leads, and interconnections. Further, because of the extreme compactness of the socket assembly and the component structures, difficulties encountered in handling of the socket assembly during fabrication thereof and during assembly into an associated camera are a significant consideraton.

OBJECTS OF THE INVENTION

It is a general object of this invention to provide an improved flash socket assembly for use in a photographic flash illumination system which employs as its source of luminous energy a disposable multilamp flash assembly having at least one array of lamps of common orientation and which includes a flash selecting control center which selects the lamp or lamps to be ignited when a firing command is given.

3,745,895 flash assembly 10 is shown as comprising a first linear array of lamps 12 and a second oppositely facing linear array of lamps 14. A support structure 16 supports the arrays of lamps 12, 14 and a relatively thin, shallow connector blade 18 which extends downwardly therefrom and carries on opposite faces first and second sets of terminals for the lamps.

FIG. 1 shows the terminals as taking the form of a set of terminal strips 20 disposed in parallel along the direction in which the flash assembly 10 is inserted into a socket assembly. A similar set of terminal strips (not shown) on the opposite face of the connector blade 18 are electrically connected to the array of lamps 14 facing in the corresponding direction (rearward in FIG. 1).

The FIG. 2 schematic diagram illustrates the flash assembly 10 as being electrically interfaced with a flash selecting system 22 through a plurality of leads 24 which terminate in contact members 26 making engagement with the terminal strips 20. As shown clearly in FIG. 2, six terminal strips are provided for the five lamps in each array. The sixth terminal strip, designated 20α in FIG. 2, is a ground terminal connected to a common ground wire for the lamps.

A more detailed description of the flash selecting system and associated structures will be given below in connection with a description of support structures therefor which embody the teachings of this invention.

The flash selecting system 22, shown in black box form in FIG. 2, may take any of a variety of forms but preferably comprises a static electronic flash sequencing or programming circuit, as shown for example in the abovementioned U.S. Pat. No. 3,618,492. A flash selecting system such as the system shown and described in the referent patent is capable of selecting a lamp or lamps in an operatively connected flash assembly according to a predetermined sequencing or other selection program. A flash illumination system of the nature described has no moving parts, may be programmed with a wide range of flash selection programs, is capable of automatically avoiding defective lamps, and has many other advantageous characteristics, as pointed out in detail in the said patent.

The flash selecting system described in the referent patent has a resistence monitoring capability designed to detect a defective lamp of the type characterized by a low resistance short circuit. If the resistance of a lamp having priority for ignition is sensed to have a value below a predetermined minimum value, the flash selecting system recognizes this condition as indicative of a faulty lamp and will avoid that lamp. It is thus extremely important that the distributed resistance in the electrical interfacing system which connects the flash selecting system with the lamps in the flash lamp assembly have a very low resistance value in order not to interfere with the operation of such flash selecting systems.

As suggested above, flash illumination systems with which this invention is concerned have general utility in cameras of many types and constructions; however, apparatus according to this invention is perhaps most useful when embodied in compact cameras in which available space is at a premium. FIG. 1 shows a front portion of a folding camera 29 of a form disclosed in the above-noted U.S. Pat. held by the assignee of this invention, Nos. 3,447,437; 3,543,662; 3,561,339; and 3,587,426. The FIG. 1 camera 29 is illustrated as com prising a front assembly 30 mounted to pivot into a face-down position on a back housing plate 32 when the camera is folded for storage

The front assembly 30 is shown as including an objective lens 34 having a picture-taking axis 35, a focus wheel 36 for focusing the lens 34, and a shutter actuator 38.

The front assembly 30 includes a flash socket assembly 40 embodying the teachings of this invention; the socket assembly 40 is shown in detail in FIGS. 3-11. A boss 42 on the socket assembly 40 extends through a top wall 43 of the front assembly 30 and defines an entrance slot 44 orthogonal to picture-taking axis 35 for receiving the connector blade 18 of a flash assembly 10. The boss 42 is also useful for its minimization of the amount of depth-wise space which the socket assembly 40 must occupy within the camera front assembly 30.

The socket assembly includes blade support means for receiving the connector blade 18 of a flash assembly 10 and for guiding the blade 18 into a predetermined operative position within the socket assembly. Contact means are provided for making electrical contact with terminals on the blade, here shown as a set of terminal strips 20. The contact means comprise a stationary set of rearwardly facing resilient contact members 46 arranged to engage the forwardly facing terminal strips 20 on a connector blade with a lengthwise wiping action when a connector blade 18 is inserted into the socket assembly 40. As explained in detail below, the contact members 46 exert a predetermined loading on the blade 18 producing frictional forces which are effective to retain the flash assembly 10 securely in the socket assembly 40.

In more detail, the blade support means is illustrated as including rear support surface means, shown for example in FIG. 8 as a planar rear support surface 48, and opposed end surfaces 50,52. In the illustrated embodiment the blade support structures constitute integral parts of a socket body 54 preferably composed of an electrically insulative plastic material.

As shown, the socket body 54 includes the boss 42 as an integral part thereof in which is formed the entrance slot 44. In order to facilitate connection of a flash assembly 10 into the socket assembly 40, the socket body 54 has formed therein an outwardly beveled mouth 56 surrounding the entrance slot 44.

The contact members 46 will now be described in more detail. The contact members 46 perform a number of important functions in the socket assembly 40. First, the contact members 46 comprise part of electrical interfacing means for electrically connecting the flash selecting circuit 22 with the forwardly facing array of lamps 12 in the flash assembly 10. Equally important, the contact members 46 provide a predetermined loading of the connector blade 18 of a flash assembly 10 against the rear support surface 48 to produce frictional forces which are effective to retain the flash assembly 10 securely in the socket assembly 40.

The contact members 46 are preferably composed of a spring material having high electrical conductivity and high tensile strength such as certain berylliumcopper alloys. A nickel-silver coating is preferably applied to minimize contact resistance.

In the illustrated FIGS. 3-11 embodiment, the contact members are illustrated as each including a terminal section 58, a curved section 60 adapted to be anchored in an opening in the socket body 54, a spine 62

3,745,895

6 extending upwardly from the curved section 60, and a reverse-bent section 64 extending from the spine 62 downwardly along the direction of blade insertion for making operative electrical and mechanical engagement with a terminal strip 20 on a connector blade 18 5 inserted into the socket assembly 40.

FIG. 10 illustrates a contact member 46 as it might appear in its unstressed state. FIG. 11 illustrates the same contact member 46 as it might appear if deflected and stressed by a connector blade 18 inserted into the 10 socket assembly 40.

FIG. 9 illustrates the rearwardly facing interior surface of the socket enclosure. In order to electrically isolate the contact members 46 from each other and in order to accurately position the contact members 46 in 15 the socket assembly to insure registration with the terminal strips 20 on connector blade 18, the socket body 40 preferably has formed integrally therein a plurality of separated recesses 65, one for receiving each contact member 46. By this expedient the contact mem- 20 bers are self-aligned in the socket assembly and the possibility of electrical shorting between the contact members 46 is minimized.

In the illustrated embodiment the leads (shown schematically at 24 in FIG. 2) for connecting the described 25 flash selecting system with the contact members 46 preferably take the form of conductors 47 printed on a flexible sheet substrate 49. As shown with particular clarity in FIGS. 4-6, the printed circuit conductors 47 may be flow soldered to the terminal sections 58 of the ³⁰contact members 46. ,

The flash selecting system preferably contains solid state circuitry fabricated in the form of an integrated circuit (I.C.) chip 51, the terminals 53 of which are connected to the conductors 47. Firing commands are ³³supplied to the chip 51 through input/output terminals 55, also flow soldered to the conductors 47.

This invention is directed to the provision of an improved flash socket assembly including an electronic flash selecting circuit and circuit support means for ⁴⁰providing structural support and protection for the flash selecting circuit. The invention is implemented in the FIGS. 3—11 socket assembly 40 by means of an integral extension 68 of the socket body 54.

The extension 68 defines a smooth relatively hard ⁴⁵surface 57 for supporting the printed circuit substrate 49. Surface 57 extends around the end of the extension in order to present a maximum of support area with a minimum of occupied space. Printed circuit substrate 49 is anchored to the socket body 54 by means of stakes 59α, 59b.

In order to shield and protect the chip 51 and its associated terminals 53 and terminal connections, in accordance with this invention the extension 68 has formed therein a recess 61 receding below the support surface 57. As shown with particular clarity in FIG. 6, the chip 51 is enclosed by the walls of the recess 61 and thereby insulated from physical contact during handling of the socket assembly 40.

The extension 68 further serves to expedite and reduce the cost of fabricating the socket assembly and installing it in a photographic camera by offering a means for enabling the socket assembly to be manually grasped and manipulated.

FIGS. 12-15 illustrate an alternative socket assembly for implementing the invention; FIGS. 12, 14, and 15 are figures corresponding to FIGS. 7,10, and 11. The

FIGS. 12-15 embodiment comprises a socket assembly 69 including a socket body 70 having blade support means including forward support surface means and rear support surface means. The forward and rear support surface means have facing end marginal portions 72, 73, and 74, 75, respectively, near the ends of entrance slot 76 separated by a distance which is slightly greater than the thickness of a connector blade 18 for firmly engaging and supporting marginal end portions of the connector blade 18, designated 78,80 in FIG. 8.

Considering the FIGS. 12-15 structure from another viewpoint it can be seen that the rear support surface is recessed such that connector blade 18 is loaded against the rear side marginal portions 74, 75 thereby greatly relieving the tolerance requirements which otherwise would necessarily have to be maintained across the full width of the rear support surface.

The necked end portions of the entrance slot 76 (shown with particular clarity in FIG. 13) defined by end portions 72,73,74, 75 have a number of other important functions. Because the socket assembly is so extremely shallow, the working length of the contact members is necessarily extremely short. But in order to obtain the requisite blade loading forces, the contact members 100 must have a relatively high effective spring rate. A high spring rate and a short working length, however, implies a relatively limited deflection if overstressing of the contacts is to be prevented. The necked end portions of the slot 76 act to limit pitching movement of the flash assembly 10 and thus control the stressing of the contact members 100 by connector blade 18.

As will be explained in detail below, the configuration of the contact members 100 is such as to produce a relatively high blade loading without a correspondingly high actual spring rate in the contact members 100.

In order that the tolerance requirements may also be minimized in regard to the end-to-end dimensions of the blade-receiving space within the socket assembly, the FIGS. 12-15 socket assembly 69 includes end support surfaces 88, 90 formed on lip portions 92, 94 below which are formed undercut surfaces 96, 98. By this expedient a connector blade is confined in its sideto-side movement by the end support surfaces 88, 90 only. The socket end-to-end tolerances in the FIGS.

12-15 embodiment must be held, then, only on the end support surfaces 88, 90.

³⁰ The contact members 100 in the FIGS. 12-15 embodiment have a generally convolute configuration. The convolute configuration of the contact members acts to maximize the effective working length of the contact members 100 and the tolerable deflection of ³ the contact members before overstressing occurs. The contact members 100 each comprise an end section 102, a base section 104 for connection to leads on a printed circuit substrate 106, a spine 108, and a reverse b^{ent sect}*^on *1®· The reverse bent section 110 is illustrated as having an entrance ramp portion 112, a central portion 114, and an exit ramp portion 116.

The entrance and exit ramp portions 112, 116 assure a smooth, aesthetically pleasing insertion and with₆₅ drawal of the connector blade. The central portion 114 applies a loading force to the contiguous surface of a connector blade in a direction normal to the connector blade so as not to introduce any lifting force compo3,745,895

Fy nent which might tend to raise the connector blade from the socket assembly.

As noted above, it is desirable that the force required to insert the connector blade of a flash assembly into the socket assembly is less than the force required to withdraw the connector blade. To this end, contact members are each configured such that upon insertion of a connector blade, the reverse bent portion 110 of the contact member offers a predetermined resistance to deflection and introduces a known frictional force against the blade. The net blade insertion force is caused to fall at a predetermined level or range of levels by an appropriate selection of the spring loading force applied by the contact members, the effective entry angle and configuration of the entrance ramp portion 112, and the coefficients of friction between the connector blade and the various surfaces which it engages during insertion into the socket assembly.

The withdrawal force is caused to be greater than this insertion force by virtue of a wedging action which is developed as the connector blade is withdrawn. It can be seen from a study of FIG. 15, for example, that as the connector blade 18 is withdrawn, as a result of frictional forces developed between the connector blade 18 and the reverse bent section 110 of each contact member 100, the reverse bent section 110 will be drawn along with the connector blade, thus causing the contact member 100 to unroll slightly. As the contact member unrolls, its diameter expands, causing a wedging or pinching action of the reverse bent section 110 against the end marginal portions 74, 75 of the rear support surface. By this expedient, the flash assembly 10, in spite of the extreme shallowness of the connector blade 18, is held securely against gravitational, centrifugal, impulsive, and other forces tending to dislodge the flash assembly from the socket asembly.

The contact portion 114 of each contact member 100 is caused to be as high as possible consonant with a reasonably shallow entry angle of the entrance ramp portion 112 in order that contact will be made with the terminal strips 20 on the connector blade 18 even in a situation wherein a flash assembly 10 is not fully inserted into the socket assembly.

As discussed above, it is desirable that the contact members 100 have a relatively low spring rate in order to minimize the likelihood of overstressing, and yet it is also desirable that the contact members 100 develop a relatively high blade loading force. To this end, contact members 100 include a tip section 117 extending from the reverse bent section 110 into engagement with the spine 108 to increase the effective spring rate of the contact members 100. By this expedient, a relatively great blade loading force can be developed in a contact member having a relatively low spring rate, thus minimizing the chance that overstressing of the contact members 100 might occur. Minimization of the spring rate of the contact members 100 is also advantageous in that the wear rate of the contact members 100 and thus the change in the spring rate thereof due to wear, are correspondingly minimized.

As discussed above, it is extremely important that contact resistance of the contact members 10® engaging the terminal strips 20 be minimized. Minimization of the contact resistance is achieved by virtue of the wiping of the terminal strips 20 by the contact members as a connector blade is inserted into the socket assem8 bly, the wiping action serving to keep the terminalcontact member interfacing surfaces clean.

In order to allow prestressing of the contact members so as to increase the blade loading forces developed thereby while assuring mutual alignment of the contact members even if unequally prestressed, the socket assemblies include limiter means for abutting the contact members to define a rearward limit position thereof. The limiter means takes the form of a wedge-shaped projection 130 formed integrally with the socket body which engages the entrance ramp portions of the contact members. Other structures for accomplishing the described limiting and aligning functions are contemplated.

In accordance with this invention the socket assembly 69 is provided with an extension 132, a portion of which is shown in FIGS. 12-15. The extension 132 may have the same construction and functions as does the extension 68 in the FIGS. 3-11 embodiment.

The invention is not limited to the particular details of construction of the embodiments depicted, and it is contemplated that various and other modifications and applications will occur to those skilled in the art.

Therefore, because certain changes may be made in the above-described apparatus without departing from the true spirit and scope of the invention herein involved, it is intended that the subject matter of the above depiction shall be interpreted as illustrative and not in a limiting sense.