Cam actuated switch assembly

[57] ABSTRACT

An electro-mechanical, plug-in device with a rotating cam which operates contact equipped, paired leaf-springs to provide specific open and closed electrical circuits in prescribed cyclic patterns. The cam is rotated by an AC synchronous motor mounted within the cam. The cam has lobes on its surface representative of a plurality of timing sequences. The leaf-springs are cantilever mounted in spaced-apart pairs in a plug base. In some embodiments the AC synchronous motor is operated directly from a sixty cycles per second external source while in another embodiment a solid-state nonpolarized DC to AC inverter is mounted on the plug base of the device to convert power from an external D.C. source into alternating current to operate the cam motor.

Claims, 21 Drawing Figures

<img file="US3679988A_D0001.tif" />

PATENTED Μ 2 51972

3,679,988

SHEET 1 OF 8

<img file="US3679988A_D0002.tif" />

<img file="US3679988A_D0003.tif" />

PATENTED JUL 25 m

3.679.988

MET 2 OF 8

<img file="US3679988A_D0004.tif" />

<img file="US3679988A_D0005.tif" />

PATENTED JUL 2 5 1972

3.679,988

SHEET 3 OF 8

<img file="US3679988A_D0006.tif" />

PATENTED JUL 2 5 1972

3.679,988

SHEET H OF 8

7^2-.

7^3-F

278270-0268-o274258— 26^7 25o^~ 247— 252'tE 262^ 266-«— 272256-^25/?-°— 260-°—

2/7-22^1 278^s

<img file="US3679988A_D0007.tif" />

<img file="US3679988A_D0008.tif" />

MOTOR CIRCUIT

RING

RING °---v FLASH 1

P---- ---3----_T flash

- BUSY

L..... -------~° ⁴ WINK r-- _x—:— o---* WINK

<img file="US3679988A_D0009.tif" />

<img file="US3679988A_D0010.tif" />

<img file="US3679988A_D0011.tif" />

timing IN milliseconds

<td> MOTOR CIRCUIT</td><td></td><td></td><td></td><td></td>

<td rowspan="3"> 1ST. ring 2ND. RING</td><td></td><td></td><td></td><td></td>

<td> L</td><td></td><td></td><td></td>

<td> |</td><td></td><td></td><td></td>

<td rowspan="2"> FLASH</td><td></td><td></td><td></td><td></td>

<td> -J 1_________</td><td> -I^- 1______</td><td> _I— .1_____</td><td> _f 1_______</td>

<td> FLASH</td><td> -Γ..... 1_____</td><td> -I 1_______</td><td> _r i_______</td><td> _Γ 1_____</td>

<td rowspan="2"> BUSY WINK WINK</td><td> —Γ' 1_______</td><td> -J^-...... 1_____</td><td> _r i_______</td><td> _l i_________</td>

<td> u u</td><td> u u</td><td>^μ· u IT</td><td> ----- u u</td>

<td></td><td> u u</td><td> u LI</td><td> ' ’ U u</td><td> LT U</td>

¹ SEC. 2 SEC. 3 sec.

PATENTED JUL 25 1972

3,679,988

SHEET S OF 8

<img file="US3679988A_D0012.tif" />

PATENTEDJUL25 1972

3,679,988

SHEET 6 OF 8

<img file="US3679988A_D0013.tif" />

<img file="US3679988A_D0014.tif" />

MOTOR

BUSY

FLASH

FLASH

FLASH

WINK

WINK

WINK

9oo

<img file="US3679988A_D0015.tif" />

<img file="US3679988A_D0016.tif" />

MOTOR CIRCUIT

RING

<img file="US3679988A_D0017.tif" />

o c oooooooooo @4OaOYOUOROMOJOEQBO @ 0

F

OOOOOOOQ

TIMING IN MILLISECONDS

RING

FLASH

FLASH

FLASH

BUSY

WINK

WINK

<td></td><td></td><td></td><td></td>

<td> L_</td><td></td><td></td><td> u</td>

<td> L</td><td></td><td></td><td></td>

<td></td><td></td><td></td><td></td>

<td> -J 1_________</td><td> J 1_____</td><td> J......... I_____</td><td> J I_____</td>

<td></td><td></td><td></td><td></td>

<td> _l 1_________</td><td> J 1______</td><td> _l 1________</td><td> J |______</td>

<td></td><td></td><td></td><td></td>

<td> J ·' I________</td><td> _l 1__________</td><td> _l |_________</td><td> _| 1________</td>

<td></td><td></td><td></td><td></td>

<td> J . . 1___________</td><td> _r..... 1________</td><td> _l |_________</td><td> _J 1_________</td>

<td></td><td></td><td></td><td></td>

<td> . u u</td><td> u u</td><td> ” u u</td><td> u u</td>

<td> u u</td><td> u u</td><td> —.......u u</td><td> ..............u u</td>

<td> u u</td><td> Γ U u</td><td> u u</td><td> u u</td>

o

I SEC.

SEC.

SEC.

SEC.

PATENTED JUL 2 5 1972

3.679,988

SHEET 7 OF 8

<img file="US3679988A_D0018.tif" />

<img file="US3679988A_D0019.tif" />

3,679,988

PATENTEDM25I972 ,SHEE7 8 OF 8

<img file="US3679988A_D0020.tif" />

<img file="US3679988A_D0021.tif" />

<img file="US3679988A_D0022.tif" />

3,679,988

FIG. 4 is horizontal sectional view taken generally along the line 4—4 of FIG. 3;

FIG. 5 is a vertical sectional view taken generally alone the lineS—5 of FIG. 4;

FIG. 6 is a horizontal sectional view taken generally along the line 6—6 of FIG. 5;

FIG. 7 is a vertical sectional view taken generally along the line 7—7 of FIG. 5;

FIG. 8 is an enlarged vertical sectional view taken generally along the line 8—8 of FIG. 4 and having portions broken away;

FIG. 9 is a schematic diagram of the circuit provided in the contacts of the embodiment of FIG. 1;

FIG. 10 is a diagrammatic timing chart of the closing of the contacts of the embodiment of FIG. 1;

FIG. 11 is an enlarged vertical sectional view of a second embodiment of the invention;

FIG. 12 is a schematic diagram of a direct current inverter for the cam motor of the embodiment of FIG. 11;

FIG. 13 is a plan view of still another embodiment ofthe invention;

FIG. 14 is a side elevation view of the embodiment of FIG 13;

FIG. IS is a bottom view ofthe embodiment of FIG. 13;

FIG. 16 is a schematic diagram of the circuit provided in the contacts of the embodiment of FIG. 13;

FIG. 17 is a diagrammatic timing chart of the closing of the contacts ofthe embodiment of FIG. 13;

FIG. 18 is horizontal sectional view taken generally along the line 18—18 of FIG. 14;

FIG. 19 is a horizontal sectional view taken generally along the line 19—19 of FIG. 14;

FIG. 20 is a horizontal sectional view taken generally along 35 the line 20—20 of FIG. 14;

FIG. 21 is a vertical sectional view taken generally along the line 21 —21 of FIG. 13 and having portions broken away.

DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS

Referring now more particularly to FIGS. 1, 2, 3, 4, 5, and 8, there is shown a preferred embodiment of the invention comprising a generally rectangular housing or casing 100 having inset screws 102 at diagonally opposite corners threaded through lugs 104 in a pair of spaced-apart, generally parallel, upwardly extending frame end pieces 106 and 107. The spaced-apart end pieces 106 and 107 are mounted at their lower ends by inset screws 108 to generally parallel, upwardly extending bosses 110 and 111 located at opposite ends of a plug base 112.

A generally cylindrical, hollow cam 114 is mounted for rotation about an axis 115 between the end pieces 106 and 107. A constant speed motor 116 which may be governed or synchronous, is mounted with an encased reduction gear assembly co-axially within the hollow cam 114. As used in this description, the term “co-axial or co-axially shall mean along or about the axis 115 and the term radially” shall be with respect to the axis 115.

The motor 116 illustratively may be of the type disclosed in U.S. Pat. No. 3,495,113 issued to Arthur W. Haydon on Feb. 10, 1970. Such a motor is self-starting, unidirectional, and has a permanent magnet rotor whose axial length exceeds its diameter. The motor is described more fully in the above patent. It is extremely efficient and requires only one watt of alternating current to begin operation and when started continues to run on ’4 watt or even less.

The cam 114 is made of a phenolic resin and is closed at one end by a cylindrical disc 118 which is formed as part of the cam. After the motor and gear assembly 116 is inserted within the cam the other end of the cam is closed with a cylindrical disc 120 which is force-fitted within the cam end.

A non-rotating, hollow shaft 122 projects from one end of the motor assembly 116 along the axis 115 and through a coaxial bore 124 through the end disc 120. The end ofthe shaft

CAM ACTUATED SWITCH ASSEMBLY

BACKGROUND OFTHE INVENTION

The present invention relates to electro-mechanical devices, sometimes known as “interrupters”, for effecting repetitive control functions, including the repetitive timing of control signals of predetermined duration necessary in multiple telephone circuits. In such telephone circuits it is frequently desirable to provide a repetitive or cyclical signal of predetermined duration, such as a “wink” signal in the form of a blinking light to apprise the telephone user of the conditions of one or more of the circuits.

Control equipment for telephone circuitry must be compact, inexpensive, extremely reliable, quiet, capable of operation over long periods of time with little maintenance, and must not generate transient signals which interfere with the basic operation of the telephone circuit.

The present invention satisfies these requirements by a novel design which additionally simplifies the manufacturing process of such interrupters.

SUMMARY OF THE INVENTION

A preferred embodiment of the present invention comprises a hollow cylindrical cam made of insulating material mounted for rotation about an axis and driven through a gear assembly by a small synchronous motor mounted co-axially within the cam. Contact equipped leaf-springs project upwardly in pairs from an insulated base, each leaf-spring having one or more contacts mounted on it opposite a corresponding contact of the other leaf-spring of the pair, and with the leaf-springs of each pair mounted on opposite sides of insulating sheets which are encased in a plug type base. The ends of the leaf-springs encased within the base are welded to plug contacts which protrude from the bottom of the base.

At least one leaf-spring of each pair is tipped with a cam follower which it resiliently presses against lobes on the exterior of the cam to open and close the contacts in prescribed cyclic patterns as the cam is rotated.

The entire assembly is protected by a transparent cover 49 detachably affixed to the base. Because of the welded connections between the leaf-springs and their corresponding plug contacts, no soldered connections are necessary within the assembly for any ofthe various circuits being controlled.

In one preferred embodiment the AC synchronous motor is 45 driven by an external source of alternating current at 10 volts, 60 Hz. In another preferred embodiment a solid-state inverter is mounted inside the unit on the plug base below the cam and between the spring assemblies. This solid-state inverter converts 24 volts DC from an external source into approximately 50 10 volts AC to drive the cam motor.

The device may be made extremely compact because the cam drive motor is mounted within the cam itself. By having only two soldered connections the design greatly contributes to the factor of reliability as well as ease of manufacture.

It is therefore an object of the present invention to provide a new and improved cam operated switch assembly having specific switches which open and close electrical circuits in a prescribed cyclic pattern.

Another object of the invention is to provide such a switch gQ assembly as a compact, plug-in unit.

Still further objects of the invention are to provide an easily manufactured and assembled cam operated switch assembly which is reliable, requires little maintenance, and operates with a minimum of noise.

The foregoing and other objects, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of certain preferred embodiments of the invention, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of one embodiment of the invention; FIG. 2 is a bottom view of the embodiment of FIG. 1;

FIG. 3 is a side elevation view of the embodiment of FIG. 1; 75

3,679,988

122 seats in a co-axial hole 126 in the end piece 107. A nonrotating shaft 128 projects from the opposite end of the motor and gear assembly 116 along the axis 115 through a co-axial bore Γ29 in the opposite end disc 118. A reduced portion of the end of the shaft 128 is seated within a co-axial hole 130 in the end piece 106. A bolt 132 is inserted through the hole 130 and threaded into the end of the shaft 128 holding it firmly in place against the end piece 106.

The fittings of the end discs 118 and 120 about their respective shafts 122 and 128 is such that the cam 114 may be freely rotated about the shafts by the motor 116. In this embodiment the cam is designed to be rotated in a clockwise direction as viewed in FIG. 8.

A cylindrical lip 134 projects inwardly of the cam 114 from the end disc 118. The lip 134 has gear teeth upon its radially inner surface which engage the teeth of a pinion gear 136 projecting from the motor and gear assembly 116.

The power leads 138 and 139 of the motor 116 pass through the hollow shaft 122 to emerge on the outside of the end piece 107. Each of the leads 138 and 139 is soldered at its end to a separate one of a pair of contacts 140 and 141 projecting upwardly from the base 112. The contacts 140 and 141 are spot welded at their ends to separate terminal plugs 142 and 143, respectively.

Telephone equipment manufacturers sometimes require that in electromechanical switches of this type the surfaces of the mating contacts during closure be parallel to each other and that the width of each contact must fall entirely within the length of its mating contact. A further requirement often made is that the pressure between the closed contacts be of a prescribed minimum.

The present invention meets these requirements by having pairs of opposed leaf-spring switches generally designated 144, cantilever mounted in the plug base. At least one leafspring of a pair has its own cam follower affixed to its end. The pairs of leaf-springs of the present invention are generally of two types.

The first type is illustrated more clearly in FIGS. 4 and 8. A pair of leaf-springs 146 and 148 are cantilever mounted in the plug base 112 in a spaced apart relationship, with the leafspring 146 being closest to the cam 114 and the leaf-spring 148 being radially spaced furtherest from the cam. The leafsprings 146 and 148 are located on the right side of the base plug 112 as it is viewed in FIG. 8 and at a distance from the end piece 106 which is approximately equal to one-fourth of the length of the cam 114.

A cam follower 150 is fitted on to the end of the leaf-spring 146. The cam followers of the invention may be made of a number of substances. By way of example only, in one preferred embodiment they are made of acetel resin molding compound. In other embodiments the cam followers are made of nylon which is injection molded onto the leaf-spring. As can be seen from FIG. 4 and FIG. 8, the configuration of particular cam followers depends upon the function to be served as will be explained more fully below.

The leaf-spring 146 is generally straight, and projects upwardly from the plug base 112 to approximately the height of the cam’s rotational axis 115. The leaf-spring 146 has a slight bend 151 inward toward the cam 114 at the leaf-spring end closest to the cam. The bend causes the leaf-spring to resiliently press the cam follower 150 against the cam.

The surface of the cam follower 150 which is in contact with the cam is contoured to fit the rounded surface of the cam and rides on an annular portion 152 of the cam surface which does not have any cam lobes impressed upon it. Thus the cam follower 150 and the leaf-spring 146 are not moved radially outward by rotation of the cam 114.

The leaf-spring 148 is mounted in a cantilevered, upright position in the plug base 112 substantially parallel to the leafspring 146, and has an inward bend 154 at its midpoint. The bend 154 causes the leaf-spring 148 to resiliently press against the leaf-spring 146 such that the oppositely aligned switch contacts 156 and 158 mounted on the leaf-springs 146 and 148, respectively, are normally pressed together.

A cam follower 160 is force-fitted over the upper end of the leaf-spring 148. A series of four ramp shaped lobes 162 are evenly spaced about the periphery of the cam 114 at a point approximately one fourth the cam’s length distant from the end piece 106. As the cam 114 rotates, the lobes 162 move the cam follower 160 away from the axis of rotation of the cam thus separating the contacts 156 and 158 and opening the electric circuit between the leaf-springs 146 and 148 in a timed relationship with the rotation of the cam.

A second type of switch assembly is illustrated by the pair of cantilevered leaf-springs 164 and 166 mounted in the plug base 112 in a spaced apart, parallel relationship with the leafspring 164 being radially closest to the cam 114. The leafsprings 164 and 166 are located on the side of the plug base 112 opposite the leaf-springs 146 and 148 and at the end of the plug base closest to the end piece 106.

The leaf-spring 164 is cantilever mounted in the plug base 112 and extends upward from the base to approximately the same height from the plug base 112 as the height of the axis of rotation 115 of the cam. The upper end of the leaf-spring 164 has force-fitted upon it a cam follower 168 which is generally in the shape of an upward pointing arrowhead which has its point cut off. The leaf-spring 164 is mounted in such a manner as to resiliently press the cam follower 168 against the outer surface of the cam 114.

The leaf-spring 166 is mounted in a cantilevered position in the base 112, extends upwardly to a height slightly above the height of the leaf-spring 164, and is substantially parallel to the leaf-spring 164. A cam follower 170 is mounted on the upper end of the leaf-spring 166. The cam follower 170 is provided with a recess 172 in its lower and radially inner portion which accommodates the cam follower 168 of the leaf-spring 164.

The leaf-springs 164 and 166 are equipped with oppositely aligned electrical contacts 174 and 176 respectively. The contacts are mounted on the leaf-springs facing each other at a short distance below the cam follower 168. When the cam follower 168 is fully seated in the recess 172 within the cam follower 170, the cam follower 170 is held away from the cam 114 and the contact 176 is resiliently pressed against the contact 174.

As the cam 114 rotates in a clockwise direction, the cam follower 168 is pushed radially outward by a series of eight ramp shaped lobes 178 evenly spaced about the periphery of the cam 114 at its end nearest the end piece 106. The ramp shaped lobes each terminate in a step 180. The leaf-spring 166 has an inward bend 182 at approximately its mid-point, which resiliently forces the leaf-spring inward toward the axis of rotation of the cam 114 to exert a restraining force against the leaf-spring 164 through the contacts 176 and 174.

As the cam follower 168 passes over the step 180, the leafspring 164 moves radially inward from the leaf-spring 166. The cam follower 170 thereafter comes in contact with the lobe 178 and is supported by it against the inward restraining force of the leaf-spring 166. The contacts 174 and 176 are thus opened and remain open until the cam follower 170 passes over the step 180, at which time the cam followei; 170 is again seated upon the cam follower 168 and the contacts are closed.

A switch comprised of a set of paired, contact equipped leaf-springs 184 and 185 of substantially identical construction and mounting as the leaf-springs 164 and 166, respectively, is located adjacent the leaf-springs 164 and 166 and operated by the same cam lobe 178.

At approximately the mid-position of the cam 114 are a second set of eight evenly spaced cam lobes 186 of substantially the same configuration and circumferential location about the cam as the lobes 178. The lobes 186 operate two other sets of paired, contact equipped leaf-springs 188, 189 and 190, 191, which are of substantially identical construction and mounting as the leaf-springs 164 and 166. They are located in the middle of the same side of the plug base 112 as the leaf-springs 164 and 166.

3,679,988

Between the lobes 162 and the lobes 178 is the uncontoured portion 152 of the cam surface having no lobes which was previously discussed in a reference to the leaf-springs 146 and 148. Between the lobes 162 and the lobes 186 is a correspondingly uncontoured section 192 of the cam 114.

A contact equipped leaf-spring 194, of substantially identical construction and mounting as the leaf-spring 146 but which in the plan view of FIG. 4 is a mirror image of the leafspring 146, rides with its cam follower in the uncontoured section 192. A contact equipped leaf-spring 196 of substantially identical construction and mounting as the leaf-spring 148, but which is a mirror image in the plan view of FIG. 4 of the leaf-spring contact 148, is operated by the lobes 162 in the same manner as the lobes 162 operate the leaf-spring contact 148. The leaf-springs 194 and 196 are parallel and have their contacts oppositely aligned. They are mounted adjacent to the paired leaf-springs 146 and 148 to open and close substantially simultaneously with the contacts of the leaf-springs 146 and 148 as the cam is rotated. The leaf-spring 196 is radially more distant from the axis 115 than the leaf-spring 194.

An uncontoured section 198 of the cam lies next to the lobes 186 on the side opposite the uncontoured section 192. Next to this uncontoured section 198 and opposite the lobes 186 are four raised lobes 200 of substantially identical construction, shape, and circumferential location as the lobes 162.

A contact equipped leaf-spring 202, of substantially identical construction and mounting as the leaf-spring 146, rides cam. A second contact equipped leaf-spring 204 which is mounted substantially parallel to the leaf-spring 202 and radially more distant from the axis 115, and which is of substantially identical construction and mounting as the leaf-spring „„ „

148, rides with its cam follower upon the series of lobes 200. 35 as the cam is rotated. The leaf-springs 202 and 204 are located approximately five eighths of the length of the cam 114 distant from the end piece 106 andon the same side of the plug base 112 as the leafsprings 146 and 148. The contacts of the leaf-springs 202 and springs 202 and 204 open and close substantially simultaneously with the contacts of the leaf-springs 146 and 148 as the cam 114 is rotated.

On the side of the lobes 200 opposite the side adjacent the uncontoured section 198 is still another uncontoured section 206 of the cam surface. This uncontoured section 206 is approximately three times as wide as the uncontoured sections 152, 192, or 198, which have substantially identical widths.

A contact equipped leaf-spring 208, of substantially identical construction and mounting as the leaf-spring 196, rides with its cam follower upon the lobes 200. The leaf-spring 208 is mounted adjacent the leaf-spring 204. A contact equipped leaf-spring 210, of substantially identical construction and mounting as the leaf-spring 194, rides with its cam follower upon the uncontoured section 206. The leaf-spring 208 is radially more distant from the axis 115 than the leaf-spring 210. The leaf-springs 208 and 210 are arranged in a parallel spaced-apart relationship and have oppositely aligned conthe contacts of the leaf-springs 146 and 148, 194 and 196, and 202 and 204 as the cam 114 is rotated.

Still another set of contact equipped leaf-springs 212 and 214 are located directly opposite the leaf-springs 208 and 210 j--j;---...... ...

axis 115. These leaf-springs 212 and 214 are of substantially identical construction and mounting as the leaf-springs 146 and 148 respectively. The leaf-spring 214 is more radially distant from the axis 115 than the leaf-spring 212 and is paraltacts are oppositely aligned to mate with each other. The cam follower of the leaf-spring contact 212 rides in the uncontoured surface 206 and the cam follower of the leaf-spring 214 rides on the lobes 200 to open and close the contacts as the cam is rotated.

Next adjacent the uncontoured section 206 on the side opposite the lobes 200 is a section 216 having a single lobe which extends over approximately three quarters of the circumference of the cam 114. The effective length of the ramp shaped lobe 216 may vary from 75 percent of the circumference of the cam to 77.75 percent of the circumference of the cam. In other embodiments it may extend over other fractions, depending upon the operation desired as will be explained further in the description.

A pair of contact equipped leaf-springs 218 and 220, corresponding in construction and mounting to the leaf-springs 146 and 148, respectively, are mounted in a spaced-apart relationship and are located next adjacent to the leaf-springs 208 and 210. The leaf-spring 218 rides with its cam follower on the uncontoured surface 206 while the leaf-spring 220 rides with its cam follower being operated by the lobe 216. The leafsprings 218 and 220 have oppositely aligned contacts which separate when the leaf-spring 220 is being pushed radially outward by the lobe 216.

An uncontoured section 222 of the cam is adjacent to the lobe 216 on the side opposite the uncontoured section 206. A pair of contact equipped leaf-springs 224 and 226 of substantially identical construction and mounting as the leaf-springs 25 194 and 196, respectively, are mounted in a parallel, spacedapart relationship and are located adjacent to the leaf-springs 218 and 220. Of the pair, the leaf-spring 226 is the more radially distant from the axis 115. The contacts of the leaf-springs 224 and 226 are oppositely aligned and mate with each other.

------3 cam follower on the uncontoured surface 222 while the leaf-spring 226 rides with its cam follower being operated by the lobe 216. The contacts of the leaf-springs 224 and 226 are opened when the cam follower of the leaf-spring 226 is pushed radially outward by the lobe 216

At the end of the cam 114 and adjacent to the uncontoured section 222 is a single lobe 228 of short circumferential length compared to the other lobes. On the side of the cam opposite the leaf-springs 224 and 226 are a pair of contact equipped mounting to the leaf-springs 146 and 148, respectively. They are mounted in a parallel, spaced-apart relationship with the leaf-spring 230 being radially closest to the axis 115. The leafsprings 230 and 232 have oppositely aligned contacts which mate with each other. The leaf-spring 230 rides with its cam follower on the uncontoured section of the cam 222. The leafspring 232 rides with its cam follower being operated by the ramp shaped lobe 228. The contacts of the leaf-springs 230 50 ^3η^ ²³² remain normally closed and are opened when the lobe 228 pushes the leaf-spring 232 radially outward.

During assembly the radially inner and radially outer leafsprings are stamped from a flat, conductive material, and are cemented to separate insulating sheets. The leaf-springs are 55 then bent perpendicularly to the surfaces of the sheets at their edges and are bent in such a way that the leaf-springs of each pair are parallel to and spaced apart from each other. The ends of the leaf-springs which terminate upon the sides of the sheets are welded to plug contacts. Referring now more parmounting of the leaf-springs 164 and 166.

The leaf-springs 164 and 166 are stamped from a flat conductive material. The leaf-spring 164 is affixed to the top surface of an insulating sheet 234 as by heat-cementing, gluing or to the plane of the sheet 234 in an upward direction so that it is in an L-shape, having a terminal leg affixed to the insulating sheet 234 and an exposed leg.

The leaf-spring 166 is affixed to the bottom surface of an in_{r r}.----------.j the plane of the sheet 235 in an upward direction so that it is L-shaped and having a terminal leg and an exposed leg. The right angle bend 236 in leaf-spring 164 is separated from the right angle bend 238 in the leaf-spring 166. A bar of insulating 75 material 240 is placed between the leaf-springs 164 and 166 . . — --O - ·*·“ —-T UUU wppuouciy dUKUC with its cam follower on the uncontoured section 198 of the 30 The leaf-spring 224 rides with its C* O m A &lt;A A #Α V* »-l A AH 4 a — * — 1 ’ * a .&gt;

_W a~a ... .. , ir. , · ¹ ®------- _BZX auu 4.41U Ui C it pair Ol COHiaCl equipped

204 are oppositely aligned. Together the contacts of the leaf- 40 leaf-springs 230 and 232, corresponding in construction and

Q IT Γ1Π OC e fl fl *7 ο n /* &gt; fB/fl /A·^ a a —* ~4 -A 1 — — — t—_a . I * it * .

,. , - ·- --------- —-4- w r*^u&amp; vviuuvie, SXVLU111UH nuw 11IU1 c paracts which open and close substantially simultaneously with ₆₀ ticularly to FIG. 8, the above arrangement is illustrated by the the contacts nf thf» Ipnf-crtrinoe nnrl l21fi 1O4nr.rlinc---1 _____4i___c.t _ 1 - . .___ * •__.· .· 1- i · .. ‘ ° ------- --- ..wwiuwug ouvvt as. uy iicai-uciiicnung, £iuin2 0Γ in a direction which is perpendicular to the cam’s rotational ₆5 other means. The leaf-spring 164 is bent at 236 perpendicular aXIS IIS I nPCA Ipar-Cnrinne 'll) A ——a -Γ a..Ua* *.· n_ . a _Λ . . ____ rr ι_Λι 4_Λ . , _x a . , - . a —¹--- cuiMtu ιυ uic uuuoiii sunace oi an inlel to and spaced-apart from the leaf-spring 212. Their con- 70 sulating sheet 235 and is likewise bent at 238 perpendicular to tacts 3ΓΑ ηηηηβΐίΑΐν alirmarl tz&gt; atra + U A A aU A*U a— T1 ___ x.1 . 1 ' o.a . a — _ . · ·

3,679 7 just above the right angle bends 236 and 238 to prevent the leaf-springs from contacting each other and to stabilize them in their cantilevered mounting position.

A substantially flat plug contact 242 is welded to the terminal leg of the leaf-spring 164. The plug contact 242 projects downwardly through holes in the insulating sheets 234 and 235 to protrude from the bottom of the plug base 112. A substantially flat plug contact 244 is welded to the terminal leg of the leaf-spring 166. The plug contact 244 projects downwardly from the bottom surface of the insulating sheet 235 to protrude from the bottom of the plug base 112. The plug contacts 242 and 244 are substantially flat and are oriented perpendicularly to each other. The other radially inner leaf-springs 146,184, 188, 190, 202,210, 212, 218, 224 and 230 are mounted in a fashion similar to the mounting of the leaf-spring 164 on the upper surface of the insulating sheet 234. These leaf-springs also have plug contacts welded to their terminal legs which project downwardly through holes in the sheets 234 and 235 to protrude from the bottom of the plug base 112 as will be described further in more detail. The remaining radially outer leaf-springs 148, 185, 189, 191, 196, 204, 208, 214, 220, 226 and 232 are mounted in a fashion similar to the mounting of the leaf-spring 166 on the bottom surface of the insulating sheet 235 and have plug contacts welded to their terminal legs which protrude from the bottom of the plug base 112. The insulating sheets 234 and 235 are stacked so that the combined thicknesses of both sheets separate the terminal legs of the radially inner leaf-springs from the radially outer leaf-springs. The stacked sheets together with the plug contacts are fitted in a recess 245 in the plug base 112. A cover 246 of insulating material is cemented or otherwise affixed to the top surface of the insulating sheet 234 to close off the recess 245.

Adjacent to and oriented in the same plane as the plug contact 242 is a substantially flat plug contact 247. The plug contact 247 is welded to the terminal leg of the leaf-spring 146 on the insulating sheet 234. In general the arrangement of the other plug contacts, which are all substantially flat, is illustrated by the arrangement of the plug contacts 242, 244, and 247; two plug contacts are oriented in the same plane while the third plug contact is oriented in a perpendicular plane. This arrangement of three contacts is repeated at spaced intervals along the plug base 112 in the direction of the axis 115, as is readily apparent from the bottom view of the cam actuated switch assembly in FIG. 2.

Referring now more particularly to FIG. 6 the circuit arrangement of the leaf-springs and their contact plugs is shown in detail. In some cases the leaf-springs of more then one pair are stamped from the same piece of material and have their terminal ends welded to a single plug contact. Thus the leafspring 184 is stamped from the same piece of material as the leaf-spring 164 and together they are welded at their terminal end to the plug contact 242. The leaf-spring 185, which is the outer leaf-spring of the pair 184 and 185, has its terminal end within the plug base 112 welded to a plug contact 248.

The leaf-springs 202 and 210 are stamped from the same piece of material and their terminal end within the plug base 112 is welded to the plug contact 250. The end of the leafspring 194 which terminates in the base 112 is welded to a plug contact 252. The end of the leaf-spring 189 which terminates in the plug base 112 is welded to a plug contact 254. The leaf-springs 188 and 190 are stamped from the same piece of material which is welded at its terminal end within the plug base 112 to a plug contact 256. The leaf-spring 204 terminates at an end within the plug base 112 which is welded to a plug contact 258. The leaf-spring 191 which is the outer leaf-spring of the pair of leaf-springs 190 and 191 terminates at an end within the base 112 which is welded to a plug contact 260. The leaf-springs 148 and 196 are stamped from the same piece of material welded to a plug contact 262.

The leaf-spring 208 has its terminal end within the plug base 112 welded to a plug contact 264. The leaf-spring 212 has its terminal end within the plug base 112 welded to a plug contact

988

266. The leaf-spring 224 has its terminal end within the plug base 112 welded to a plug contact 268. The leaf-spring 218 has its terminal end within the plug base 112 welded to a plug contact 270.

The leaf-spring 214 has its terminal end within the base 112 welded to a plug Contact 272. The leaf-spring 226 has its terminal end within the plug base 112 welded to a plug contact 274. The leaf-spring 220 has its terminal end within the plug base 112 welded to a plug contact 276. The leaf-spring 232 has its terminal end within the plug base 112 welded to a plug contact 278.

The plug contacts 247, 252, 258, 264, 270, 276, and 142 are arranged in a row along an axis parallel to the axis 115. The plug contacts 242, 250, 256, 262, 268, 274, and 143 are ⁵ arranged in a row along an axis parallel to the axis 115 and adjacent the row of plug contacts 246-142. As was discussed above the plug contacts 242 and 247 are oriented in the same plane and likewise the plug contacts 250 and 252, 256 and ₂₀ 258, 262 and 264, 268 and 270, 274 and 276, and 143 and 142 are aligned in the same planes, the planes being parallel to each other.

The plug contacts 244, 248, 254, 260, 266, 272, and 278 are arranged in a row along an axis parallel to the axis 115 and 25 adjacent the row of contacts 242-143. The contacts 242-143 lie between the contacts 247-142 and the contacts 244-278. The contacts 244-278 are each oriented in a plane perpendicular to the planes containing the other contacts as was discussed above.

Referring now more particularly to FIGS. 9 and 10 the circuit diagram of the cam actuated switch as well as the timing relationship of the switches are illustrated. In FIG. 9 the numbers appearing at the left hand portion of the figure correspond to the plug contacts described above. In FIG. 10 the 35 contact closures of the various leaf-spring switches are illustrated over a four second timing period which is the time required for a complete revolution of the cam 114.

The “motor” switch comprised of the leaf-springs 230 and 232 allows control ofthe operation of the motor. The switch is 40 normally closed, thereby allowing power to be supplied to the motor through the plug contacts 142 and 143. The switch is opened by the action ofthe lobe 228 against the cam follower ofthe leaf-spring 232. This ensures that the cam will cease its rotation in a predetermined position leaving each switch in a 45 predetermined setting of being opened or closed. The motor may be initially started or restarted by the application of electrical power through the contacts 142 and 143 which bypasses the leaf-spring “motor” switch.

The first and second “ring” switches are comprised of the paired leaf-springs 218 and 220 and 224 and 226. The “ring” leaf-spring contacts are normally held open by the action of the lobe 216 against the cam followers of the leaf-springs 220 and 226. The “ring” are closed during the first second of the g j cycle for a duration of 890 to 1000 milliseconds.

The first and second “flash” switches are comprised of the leaf-springs 202 and 204 and 208 and 210. The “flash” switches are opened and closed periodically by the lobes 200. More specifically the contacts of these leaf-springs are closed ¢0 for a duration of approximately 450 and 550 milliseconds during each quarter of a complete revolution of the cam. Likewise the “busy” switch comprised of the leaf-springs 212 and 214 on the opposite side of the cam from the leaf-springs 202, 204, 208 and 210 is opened and closed by the lobe 200 65 for approximately the same duration as the “flash” switches during each quarter cycle of a complete revolution of the cam.

The first “wink” switch is comprised of the contact equipped leaf-springs 164, 166, 184 and 185. It is normally closed but it is opened by the action of the lobes 178 against 70 the leaf-spring cam followers for a period of approximately 20 to 50 milliseconds at eight evenly spaced periods during a complete revolution of the cam 114. A second “wink” switch is comprised of the contact equipped leaf-springs 188, 189, 190 and 191. This second “wink” switch opens and closes sub75 stantially simultaneously with the first “wink” switch.

3,679,988

The assembled cam actuated switch assembly of the embodiment of FIGS. 1 through 10 is designed to be plugged into a receptacle (not shown) in a telephone circuit. The unit is held in the receptacle by a pair of captive through-bolts 280 and 282 which extend from lugs 284 and 286 on the end pieces 106 and 107 through opposite corners of the plug base 112 to be threadably received in the receptacle mounting (not shown).

Referring now more particularly to FIGS. 11 and 12 another embodiment of the present invention is shown comprising the cam operated switch assembly described above in reference to FIGS. 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 with the addition of a solid-state inverter circuit 300 mounted on the plug base 112' of the device beneath the cam 114' and between the end pieces 106' and 107'. The solid-state non-polarized DC to AC inverter 300 converts power from an external direct current source into 60 cycle per second alternating current to operate the cam motor 116'.

Referring now more particularly to FIG. 12 the circuitry of the solid-state inverter is illustrated schematically. An input lead 302 is connected to the plug contact 143' and an input lead 304 is connected to the plug contact 142'. The leads 302 and 304 are connected to opposite sides of a non-polarizing, diode rectifier bridge circuit 306. The positive output of the 25 rectifier bridge circuit 306 is connected to a lead 308. The negative output of the rectifier bridge circuit 306 is connected to a lead 310.

A zener diode 312 has an anode terminal connected to the lead 310 and a cathode terminal connected to one end of a re- 30 sistor 314. The opposite end of the resistor 314 is connected to the lead 308. The breakdown voltage of the zener diode 312 is less than the voltage to be applied between the leads 308 and 310. Thus the zener diode 312 and the resistor 314 form a regulated voltage divider network.

A relaxation oscillator 316 is connected in parallel with the zener diode 312 between the lead 310 and the cathode terminal of the zener diode. The input lead 318 of the oscillator 316 is connected to the cathode terminal of the zener diode. The oscillator 316 is comprised of resistors RI, R2, R3 and R4 40 together with transistor T1 and unijunction transistor UJT1 and capacitor Cl to form a relaxation oscillator. The resistor RI connected between the lead 318 and the emitter of the transistor UJT1 is selected to have a value such that the natu- „ „„„„„ _{V(U11 W11I}, ral frequency of the relaxation oscillator is substantially 120 ⁴⁵ 408 mounted within the cycles per second. The oscillator output from the collector of the transistor T1 appears at lead 320 in the form of positive pulses.

A motor driver circuit 322 is connected between the leads 308 and 310. The driver circuit 322 is comprised of transistors T2, T3, T4, and T5, resistors R5, R6, R7 and R8, and capacitors C2, C3, C4, and C5 to form a flip-flop driver network. The output lead 320 connects the driver circuit 322 with the oscillator 316.

The emitters, of the transistors T2 and T4 are connected to the lead 308 while the collector of the PNP transistor T2 is connected to the collector of the NPN transistor T5. The emitter of the NPN transistor T5 and the emitter of the NPN transistor T3 are both connected to the lead 310. The collector of the PNP transistor T4 is connected to the collector of the NPN transistor T3. The resistor R5 is connected between the base of the transistor T2 and the collector of the transistor T4. The capacitor C2 is connected between the base of the transistor T2 and the lead 320.

The resistor R7 is connected between the base of the transistor T4 and the collector of the transistor T2. The capacitor C4 is connected between the base of the transistor T4 and the lead 320. The resistor R6 and the capacitor C3 are connected in parallel between the base of the transistor T3 and the collector of the transistor T5. The resistor R8 and the capacitor C5 are connected parallel between the base of the transistor TS and the collector of the transistor T3.

The cam motor 116' is connected by its power lead 138' to the collector of the transistor T3. The other motor power lead

139' is connected to one-side of a capacitor 324. The opposite side of the capacitor 324 is connected to the lead 310.

In operation the transistors T2 and T3 and the transistors T4 and T5 operate in pairs such that with each positive pulse applied to the lead 320 from the oscillator 316 the transistor pairs are either in a conducting (“on) state or a non-conducting (“off”) state. By way of example, assuming that the transistors T4 and T5 are off and the transistors T2 and T3 are on when a positive going spike from the oscillator 316 appears on lead 320, the transistors T4 and T5 will switch on and thereby turn the transistors T2 and T3 off.

Power then flows from the lead 308 through the transistor T4, the motor lead 138', the motor 116', and the motor lead 139' to charge the capacitor 324.

The next positive going spike applied through the lead 320 reverses the operation and turns on the transistors T2 and T3 while turning the transistors T4 and TS off. The capacitor 324 then discharges through the lead 139’, the motor 116', the lead 138 and the transistor T3. This circuit insures that a power signal having a symmetrical waveshape is applied to the motor 116'.

From the foregoing description it is apparent that although the output of the oscillator 316 is one hundred and twenty positive going spikes per second, the flip-flop driver circuit 322 goes through a complete cycle only 60 times per second and the wave shape of the power applied to the motor 116' roughly approximates a symmetrical square wave having a frequency of substantially 60 cycles per second.

While the circuitry of the solid-state inverter 300 is described above as having individual transistors, resistors, capacitors, and leads it is understood that the circuitry could be in printed circuit form, in monolithic, integrated circuit form, or any other subminiature form of circuitry.

Referring now to FIGS. 13, 14,15,16, 17,18, 19, 20 and 21 still another embodiment of the invention is shown as comprising a generally rectangular housing 400 fitted to a plug base 402 and held to the base by a mental strap member 404 which hooks on one edge of the plug base 402 and extends up and over the casing 400 to hook on the opposite edge of the plug base 402.

This embodiment of the invention is similar in construction and design to the embodiment of FIGS. 1 through 10 in that it has a hollow cam 406 which is rotated by a synchronous motor -------1-- ...j cam in a manner substantially the same as the arrangement in the first embodiment. This embodiment occupies about one half the space of the first embodiment and has 17 switching circuits instead of the 12 switching circuits of the first embodiment.

The cam 406 is mounted for rotation between a pair of spaced apart upwardly projecting end plates 410 and 412 which are mounted upon upwardly projecting bosses 414 and 416 of the plug base 402. A pair of parallel, spaced-apart, ₅₅ rigid, reinforcing members 418 and 420 extend between the end plates 410 and 412 at their tops. The members 418 and 420 are affixed to the end plates 410 and 412 by screws 419 and 421. The reinforcing members 418 and 420 are not in contact with the cam 406.

The cam 406 is rotated by the motor 408 in a clockwise direction as viewed in FIG. 21 and operates a series of contact equipped leaf-spring pairs generally designated 422. The contact equipped leaf-spring pairs are similar in construction and mounting to the leaf-spring pairs of the first embodiment. The 65 leaf-springs of each pair are stamped from a conductive, resilient material, are affixed to opposite sides of separate insulating sheets and are bent perpendicularly upward in a parallel spaced-apart relationship with each other. In a manner similar to the arrangement in the embodiment of 70 FIGS. 1 through 10 the insulating sheets are placed back to back and are encased in the plug base.

The contact equipped leaf-springs are generally of two types. Referring now to FIG. 21 the first type of contact equipped, paired leaf-springs are illustrated by the leaf-springs 75 424 and 426 which correspond in construction and mounting

3,679,988 to the leaf-springs 144 and 146 of the first embodiment. The leaf-spring 424 has a terminal end affixed to the top surface of an insulating sheet 428 encased in the plug base 402 and an upwardly extending, exposed, perpendicular portion which has a cam follower at its upper end. The leaf-spring 426 has a 5 terminal end affixed to the bottom surface of an insulating sheet 429 encased in the plug base 402 beneath the insulating sheet 428 and an upwardly extending exposed portion perpendicular to the insulating sheet 429 which is tipped with a cam follower. The leaf-springs 424 and 426 have mounted upon ¹⁰them oppositely aligned contacts 430 and 432, respectively, which mate and separate in a manner which is described below. The outer leaf-spring 426 normally resiliently presses its contact 432 against the contact 430, so that the electrical circuit between the leaf-springs is closed. ⁵

The ends of the leaf-springs 424 and 426 which terminate within the plug base 402 are each welded to separate plug pins 434 and 436, respectively. The pin 434 projects downwardly through holes in the insulating sheets 428 and 429 to emerge ₂q from the bottom of the plug base 402. The pin 436 projects downwardly from the bottom of the insulating sheet 429 to emerge from the plug base 402.

As is more clearly shown in FIG. 19 the contact equipped leaf-spring arrangement illustrated by the leaf-springs 424 and 25 426 is repeated at three other places on the left side of the cam adjacent to the leaf-springs 424 and 426 and between them and the end piece 412 as viewed in FIG. 21. The arrangement of leaf-springs is repeated again at three locations on the other side of the cam 406 opposite from the leaf-springs 424 and 30 426.

The cam followers of these paired leaf-springs are operated by a series of eight ramp-shaped lobes 438, evenly spaced about the circumference of the cam 406 at the left end of the cam as viewed in FIG. 19. Each lobe 438 has a raised step por- 35 tion 440. The contacts mounted upon the paired leaf-springs are normally closed. As the cam followers of the radially inner leaf-springs, typified by the leaf-spring 424, pass over a step portion 440 of lobe 438 the cam followers of the radially outer leaf-springs, typified by the leaf-spring 426, are each pushed +0 radially outward by the lobes 438 while the inner cam followers are not, The leaf-springs of each pair move apart and the contacts mounted upon the leaf-springs thus become separated. This opens the electrical circuit between the leafsprings of each pair. The switches comprised of these leafsprings are “wink” switches and as illustrated in the timing diagram of FIG. 17 they are momentarily opened at eight evenly spaced intervals during a complete revolution of the cam.

The second type of contact equipped, paired leaf-springs are illustrated by the leaf-springs 442 and 444 located on the right side of the cam 406 as viewed in FIG. 21 and nearly equidistant from the end pieces 410 and 412. The radially inner leaf-spring 442 has a terminal end which is mounted on 55 the top surface of the insulating sheet 428. It also has an exposed portion which is bent perpendicularly upwardly from the insulating sheet 428 and is tipped with a cam follower. The radially outer leaf-spring 444 has a terminal end which is affixed to the bottom surface of the insulating sheet 429 and an exposed portion which is bent perpendicularly upwardly from the insulating sheet 429. The upwardly projecting portion of the leaf-spring 444 is not tipped with a cam follower but instead resiliently presses against a portion of the reinforcing bar 418. 65

The leaf-springs 442 and 444 are equipped with contacts 446 and 448, respectively, which mate when the cam follower of the leaf-spring 442 is pressed outwardly by one of four ramped shaped lobes 450 evenly spaced about the circumference of the cam 406. The lobes 450 are located in the 70 center portion of the cam.

The leaf-spring arrangement typified by the leaf-springs 442 and 444 is repeated at three other intervals next adjacent to the leaf-springs 442 and 444 and at three intervals on the opposite side of the cam from the leaf-springs 442 and 444. As to 75 these latter three leaf-spring pairs, the radially outer leafsprings rest against the reinforcing bar 420 rather than the reinforcing bar 418. The switches comprised of these leafsprings are the three “flash” switches and one “busy switch.

On the cam surface next adjacent the lobes 450 on the side opposite the lobes 438 is a single lobe 452 which extends over approximately 22.25 to 25 percent of the cam’s circumference. Two pairs of contact equipped leaf-springs 454 and 456 and 458 and 460 are located on the left side of the cam 406 as viewed in FIG. 21. The leaf-springs are of substantially identical construction and mounting as the leaf-springs 442 and 444.

The leaf-springs 454 and 458 are radially closer to the axis of rotation of the cam 406 than the leaf-springs 456 and 460 which are the opposite members of each pair. The leaf-spring pair 454 and 456 is located at a distance from the end piece 410 which is approximately equal to one quarter of the length of the cam 406. The leaf-spring pair 458 and 460 is located at a distance from the end piece 410 which is approximately equal to one eighth the length of the cam 406. Each pair of leaf-springs have oppositely aligned contacts which mate when the leaf-springs 454 and 458 are pushed radially outward by the lobe 452. The switches comprised of these leafsprings are the “ring” switches.

At the end of the cam adjacent the end piece 410 is a single, circumferentially short cam lobe 462. A pair of contact equipped leaf-springs 464 and 466 of substantially identical construction and mounting as the leaf-springs 424 and 426, respectively, are located at the end of the cam adjacent the end piece 410 and on the right side of the cam as viewed in FIG. 21. The leaf-springs have oppositely aligned contacts which are normally closed and which are separated only momentarily as the lobe 462 passes beneath the cam followers attached to the ends of the leaf-springs 464 and 466. These leafsprings control the motor circuit and allow the cam to be stopped in a predetermined position.

The connections between the upwardly projecting portions of the leaf-springs are illustrated in FIG. 20, however, in other embodiments other circuit configurations may be used. The ends of the leaf-springs terminating on the insulating sheets 428 and 429 and within the plug base 402 are welded to round plug pins generally designated 468. The letter designations appearing in FIGS. 15 and 16 are for the illustrative purpose of showing the interconnections of the pins and contact equipped leaf-springs. The motor power leads 470 are soldered to contacts 472 projecting upwardly from the base 402. The contacts are welded to separate pins. In FIG. 17 the timing sequence of the switches is illustrated for a complete, four second revolution of the cam 406.

In all of the above embodiments friction on the cam bearings is reduced to a minimum by arranging the sets of paired leaf-springs on opposite sides of the cam to balance the forces exerted against the cam. Another novel feature of the design of the invention is having the resilient leaf-springs mounted or anchored at a substantial distance from the cam assembly so that flexing of the arms of the leaf-springs induces a minimum stress. The cantilever mounting feature has the additional advantage that the surfaces of the contacts on the leaf-spring pairs during closure are substantially parallel to each other and the width of each contact falls nearly entirely within the length of its mating contact. As mentioned previously, this is sometimes required by telephone equipment manufacturers.

The moving parts of a device according to the invention may operate at low speed in relation to the timing intervals involved. This keeps wear, fatigue, etc. to a minimum. The invention has the still further advantage of reducing power consumption and noise.

Still another novel feature of the invention is illustrated by the “wink” switches described above which allow highly accurate, repetitive timing of intervals of short duration. This is possible because the pairs of cam followers are arranged so that one cam follower moves sequentially over a drop-portion

3,679,988 or step of the cam lobe while the other cam follower of the pair remains in contact with the lobe as the cam is rotated.

There are several advantages in having a motor for driving the cam located co-axially within the cam itself. One such advantage is the reduction in space required. Still another advantage is a reduction in noise.

While in portions of the above description the terms upwardly, downwardly, and bottom have been used it is to be understood that the cam actuated switch assemblies of all the embodiments discussed operate in any position with respect to gravity. Thus the terms upward, downward and bottom are not meant as terms of limitation. Also, certain transistors are described above as being of the NPN or PNP type, however, in other embodiments transistors of other types may be used with appropriate changes in circuitry.

It should also be apparent that while some of the switches comprised of the leaf-spring pairs are described as being normally closed and as being opened by the action of a cam lobe against a cam follower, in other embodiments switches comprised of leaf-spring pairs could be normally open and could be closed by the action of a cam lobe against a cam follower.

The terms and expressions which have been employed here are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described, or portions thereof, it being recognized that various modifications are possible within the scope of the invention claimed.