ILLUMINATED PUSH BUTTON SWITCH

Abstract: An illuminated push button switch module (50) comprised of a lamp subassembly (76) and push button switch subassembly (74). The switch subassembly (74) is physically mounted on and electrically connected to a circuit board (60). The lamp subassembly (76) is configured for detachable spring mounting on the switch subassembly (74) enabling the lamp subassembly (76) to be manually depressed to actuate the switch subassembly (74). The spring mounting includes a pair of coil springs (334, 336) which terminate in cantilevered arms (364) to electrically contact pads (240, 242) on the lamp subassembly (76) for energizing an incandescent bulb (250) carried thereby. The lamp subassembly (76) can be easily detached from the switch subassembly (74) for bulb replacement.

Description: -1- ILLUMINATED PUSH BUTTON SWITCH FIELD OF THE INVENTION This invention relates to an illuminated push button switch module intended to be actuated by finger pressure and particularly suited for use in integrated panel displays of the type widely employed in aircraft, marine, and various industrial applications. BACKGROUND OF THE INVENTION Integrated display panels are used in a myriad of applications for controlling diverse electrical functions. Such panels typically consist of a rear printed circuit board having a plurality of push button switches mounted thereon and a front apertured plate overlaying the circuit board. Typically, a lamp, e.g. incandescent bulb, is -mounted on the circuit board adjacent each switch for illuminating a translucent chip positioned in an aperture in the front plate. SUMMARY OF THE INVENTION The present invention is directed to a small illuminated push button switch module which can be readily mounted on a printed circuit board and subsequently easily removed for replacement or repair. In accordance with a preferred embodiment, the switch module is comprised of a switch subassembly and a lamp subassembly. The switch subassembly is configured with multiple female connectors adapted to be physically 'mounted on and electrically connected to conductive pins secured to the circuit board. In accordance with a significant feature of the invention, the lamp subassembly is configured for detachable spring mounting on the switch subassembly. The spring mounting enables a user to apply finger -2- pressure to the lamp subassembly to in turn actuate the switch subassembly. In accordance with a further feature of the preferred embodiment, the perimeter of the lamp subassembly is smaller than the perimeter, in a parallel plane, of the switch subassembly, thereby enabling an apertured front plate to be secured parallel to the circuit board to sandwich the switch subassembly therebetween while also allowing the lamp subassembly to project forwardly through an aperture in the front plate. In accordance with a still further feature, each ^ lamp subassembly has an incandescent bulb mounted therein electrically connected to a pair of contact pads which automatically mate with a pair of spring contacts when the lamp subassembly is properly mounted on the switch subassembly. In accordance with a further feature of the * preferred embodiment, each spring contact is formed on the end of a substantially rigid arm cantilevered from an end coil of a coil spring. The rigid arm provides a predictable reaction force to the depression of the lamp subassembly and assures a good low resistance nonsliding contact between each spring contact and its mating contact pad. In accordance with a still further feature, each lamp subassembly is mounted so that a user can, from the front side of the apertured plate and using only his hands, detach the lamp subassembly from its switch subassembly in order to relamp the switch module. In accordance with a still feature of the invention, the switch subassembly includes a pair of fixedly mounted spaced contacts and a conductive ball mounted for movement into and out of bridging engagement with the contacts. The ball movement is controlled by a nonconductive selectively movable actuator. -3- In accordance with a different feature of the invention, the aforementioned nonconductive actuator is coupled to a push button and to a toggle mechanism which produces a reaction force on the push button to thus provide an appropriate tactile feedback to the user to indicate when the switch contacts are bridged. In accordance with a preferred embodiment of the invention, the nonconductive movable actuator comprises a plunger mounted for linear movement between a spring established quiescent position and a user established depressed position. The plunger carries a projection which in the quiescent position engages the ball to prevent it from bridging the switch contacts. As the plunger is depressed, the projection moves to a noninterfering position to permit the ball to move into bridging engagement against the switch contacts. In accordance with a further aspect. of the preferred embodiment, the plunger is coupled to ' a spring urged toggle arm mounted for pivotal movement. As the plunger is depressed, an inclined surface thereon bears -against the toggle * arm to pivot it gradually from its quiescent position. The toggle arm supplies an increasing reaction force to the plunger as it moves toward a threshhold point. Thereafter, as the toggle arm moves through the threshold point, the reaction force abruptly diminishes to provide a "snap" feel to a user depressing the plunger. In accordance with a further aspect of the preferred embodiment, a lamp housing is provided having a reflector cavity whose internal surface forms a parabola truncated by a flat metalized diffraction grating. The cavity internal surface is also preferrably metalized to enhance its reflectivity. In accordance with a feature of the preferred embodiment, an incandescent bulb mounted between the diffraction grating and the translucent chip is oriented so that its filament lies in a plane extending T/US86/01006 -4- substantially parallel to the grating to thereby enchance the uniformity of the light reflected through the chip. In accordance with a further feature of the preferred embodiment, a translucent attenuator is mounted on the bulb glass envelope between the filament and the translucent chip to prevent the filament from creating a bright spot when viewed from the front of the translucent chip. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A is an exploded isometric view of a portion of an integrated display panel and Figure IB is a schematic sectional view, both showing a preferred switch module embodiment and its relationship to a circuit board and an ' apertured front plate; Figure 2 is an exploded isometric view of the switch module of Figures 1A and IB depicting the lamp subassembly and switch subassembly thereof; Figure 3 is an exploded isometric view of the lamp subassembly of Figure 2; Figure 4 is a plan view of the lamp subassembly; Figure 5 is a sectional view taken substantially along the plane 5-5 of Figure 4; Figure 6 is an exploded isometric view of the switch subassembly of Figure 2; Figure 7 is a plan view generally depicting the mechanical and electrical interface between the lamp and switch subassemblies; Figure 8 is a sectional view taken substantially along the plane 8-8 of Figure 7; Figure 9 is a plan view of the switch subassembly in its normally open state; Figure 10 is a sectional view taken substantially along the plane 10-10 of Figure 9 showing the actuator in its quiescent undepressed position; -5- Figure 11 is a plan view of the switch subassembly in its closed state; and Figure 12 is a sectional view taken substantially along the plane 12-12 of Figure 11 showing the actuator in its depressed position. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT Attention is initially directed to Figure 1A which illustrates a portion of an integrated display panel 40 incorporating one or more illuminated push button switch modules 50 in accordance with the invention. The display panel 40 further includes a rear printed circuit board • 60 and an apertured front plate 70. Briefly, the switch module 50 is comprised of a switch subassembly 74 and a lamp subassembly 76. Prior to discussing the constructional details of the switch and lamp subassemblies 74, 76, it would be helpful to first understand how these subassemblies relate to one another when incorporated in the display panel 40. Initially, it should be noted that the switch subassembly 74 is essentially planar in shape and is mounted parallel to the front or upper surface 78 of the circuit board 60 with a depending portion 75 of the subassembly 74 fitting closely in an opening 77 in the board 60. The lamp subassembly 76 is also essentially planar in shape* and is spring mounted on the switch subassembly 74 for limited reciprocal displacement (arrow 79, Figure IB), essentially toward and away from the switch subasssembly 74. A user, by applying downward finger pressure on the lamp subassembly 76 actuates the switch subassembly in a manner to be described hereinafter. The lamp subassembly 76 additionally functions as an illuminated indicator for the switch module 50 and can be readily detached from the switch subassembly 74 for relamping. /01006 -6- Figure IB illustrates two switch modules 50, the module on the right being depicted in its quiescent position and the module on left in its actuated position. It is to be noted in Figure IB that the switch subassembly 74 has a larger perimeter than the lamp subassembly 76 so that the apertured front plate 70 can bear against the switch subassembly 74 while enabling the lamp subassembly 76 to pass through an aperture 80 in the plate 70. The rear face 82 of the plate 70 around the aperture 80 engages the upper edge surface of the switch subassembly 74 enabling the plate 70 to clamp the switch assembly 74 against the front surface 78 of the circuit board 60. Attention is now directed to Figure 2 which depicts an exploded view of the switch module 50. The switch subassembly 74 is basically comprised of a switch housing 100 defining an internal cavity 101 which accommodates the components of a switch and tactile feedback mechanism, generally designated as 102. Four female connectors 104 are preferably press fit into openings in the housing 100 for receiving and making electrical connection to conductive pins 106 soldered and/or staked to the upper surface 78 of aforementioned circuit board 60. The housing 100 defines a pair of guide channels 110 and 112 to respectively accommodate first and second mounting retainers 114, 116. The mounting retainers 114, 116 are supported within the guide channels 110, 112 on springs 120 enabling the retainers 114, 116 to move reciprocally in a direction perpendicular to the nominal plane of the housing 100. A cover plate 130 is provided to fit over the housing cavity to cover the switch and tactile feedback mechanism 102. The cover plate 130 has an opening 132 for accommodating the upper end of a plunger 134. The plunger 134, as will be discussed hereinafter, forms -7- part of the actuator of the switch and tactile feedback mechanism 102. The lamp subassembly 76 includes a substantially rectangular frame 150 having a first sidewall defining an opening 152. A retainer pin 156 extends outwardly from the first sidewall of a housing 157 fitted within the frame 150. The retainer pin 156 is intended to be detachably received within the jaws of a retainer clip 160 formed on the upper edge of mounting retainer 116. The second sidewalls of the frame 150 and housing 157 (hidden in Figure 2) are identical to the .illustrated first sidewalls and thus include a retainer pin for coupling to a retainer clip on mounting retainer 114. The lamp subassembly frame 150 defines a rectangular window 162 closed by a translucent chip 164. The chip 164 can bear suitable indicia to identify the function of the related switch subassembly, e.g. HEATER. As will be discussed hereinafter, the lamp subassembly 76 includes an energizable light source, e.g. incandescent bulb, mounted within the housing 157 beneath the window 162 to back light the translucent chip 164. When the switch module 50 is functionally mounted, as depicted in Figure IB, a lamp subassembly 76 in the quiescent position can be manually depressed (arrow 79) to in turn depress the aforementioned plunger 134 to actuate the switch and tactile feedback mechanism 102. Manual depression of the lamp subassembly 76 compresses the springs 120, which, when the depressing force is removed, return the lamp subassembly 76 to its quiescent state when the depressing force is removed. As mentioned, in addition to functioning as the push button actuator for the switch subassembly 74, the lamp subassembly 76 includes a light source for back lighting the translucent chip 164. As will be discussed hereinafter, electrical power for the light source within the lamp subassembly 86/01006 -8- 76 is coupled thereto from the circuit board 60 via two of the aforementioned female connectors 104 and through two of the springs 120. That is, when the lamp subassembly 76 is properly retained on the mounting retainers 114, 116, contact pads on the lamp subassembly 76 (not shown in Figure 2) electrically contact portions of the springs 120 to complete an electrical path to energize the light source within lamp subassembly 76. Attention is now directed to Figures 3-5 which illustrate the constructional details of the preferred lamp subassembly 76. The subassembly is comprised of the aforementioned housing 157 which is substantially rectangular in shape and includes first and second sidewalls 200 and 202. In addition to the aforementioned retainer pin 156, pins 204 and 206 extend from each of - the sidewalls. As will be seen hereinafter, whereas retainer pins 156 ' function to detachably retain the lamp subassembly 76 to the switch subassembly 74, the pins 204 and 206 function to retain the lamp housing 157 to the lamp housing frame 150. The housing 157 defines an open internal cavity 210. The interior surface 212 of the cavity, in vertical cross section (Figure 5) , is substantially parabola shaped, truncated by a central circular opening 214. In addition, a small lead .access opening 216 is formed in the interior surface 212 in close proximity to the opening 214. The lamp subassembly 76 further includes a circuit board 220 adapted to be mounted immediately beneath the lamp housing 157, as depicted in Figure 5. More particularly, the circuit board 220 is supported beneath housing 157 to close the aforementioned central circular opening 214 and to support a flat disk 224 thereon. In accordance with a significant feature of the invention, the disk 224 has a plurality of very fine grooves 226 formed on the upper surface 228 -9- thereof. The grooves, preferably in a radiating spoke pattern, form a circular diffraction grating. The upper surface 228 of disk 224, as well as the parabola shaped interior surface 212, is preferably metalized in a manner to enhance uniform reflectivity, as will be further discussed hereinafter. The disk 224 is supported on the upper surface 221 of circuit board 200. The circuit boards lower surface 230 defines first and second conductive paths 232, 234 extending from lead openings 236, 238 to contact pad areas 240, 242. As will be seen hereinafter, when the lamp subassembly 76 is operationally mounted together with the switch subassembly 74, the contact pads 240, 242 are automatically engaged by spring contacts to electrically connect the pads to the outer connectors 104 depicted in Figure 2. Continuing -with the detailed description of the lamp subassembly 76 of Figures 3-5, an energizable light source is provided, preferably an incandescent bulb 250 having first and second leads 252 and 254. The leads 252 and 254 are insertable through the access opening 216 and into the circuit board openings 236 and 238 for connection to the conductive paths 232, 234. It is preferable to mount the bulb 250 to the circuit board 220 so that the bulb filament 258 lies in a plane extending substantially parallel to the plane of the diffraction grating disk 224. In this manner, the illumination from the bulb is optimally distributed over the reflective surface formed by the cavity interior surface 212 and diffraction grating surface 228. By optimally distributing the bulb illumination over the entire reflective surface, a more uniform light intensity is produced to back light the translucent chip 164. Additionally, in order to acheive uniform intensity and minimize shadows, it is preferable that the bulb 250 have a clear glass -10- envelope 260 and that the bulb leads 252, 254 exit directly through the access opening 216. Still further, in order to enhance the uniformity of the light reflected through chip 164 and to avoid the appearance of a bright spot directly from the filament 258, it is desirable to deposit a small amount of translucent diffuser material 264 on the glass envelope 260 immediately above the filament 258. The aforementioned translucent chip 164 preferably comprises a substantially rigid piece of diffuser material, either clear or colored. Indicating indicia can be provided on the chip 164 by screening opaque characters or symbols thereon. With the chip 164 overlaying the housing cavity 210, light from the bulb 250 wil-l be efficiently reflected from the diffraction grating surface 228 and interior surface 212 through the chip 164. By optimally orienting the bulb filament 258 * and utilizing the diffuser material 264, a substantially uniform relatively high intensity light field will be reflected over the entire chip area. The utilization of. the diffraction grating disk 224, in conjunction with the truncated parabolic surface 212, forms * a very low profile, short depth, reflector which very efficiently transmits the illumination from bulb 250 through the chip 164. The lamp subassembly 76 is held together by the aforementioned lamp housing frame 150. The frame 150 comprises an essentially open rectangular structure including sidewalls 280, 282 and an overhanging upper lip 290 surrounding the aforementioned window 162. The side walls 280, 282 are identically formed and, and as can best be seen in Figure 3, include the aforementioned opening 152 and first and second pin slots 292, 294. The pin slots 292 and 294 function to slideably receive and accommodate the aforementioned pins 204, 206 extending from the side walls of housing 157. The frame 150, as well as the housing 157, -11- preferably comprise closely dimensioned molded plastic parts such that the frame 150 can be manually pressed down on the housing 157 to seat the pins 204, 206 in the frame slots 292, 294 to form an integrated substantially tight package. Fingernail grooves 296 are preferably formed in the outer surfaces of side walls 280, 282 of frame 150. The fingernail grooves extend above the front plate 70, as depicted in Figure IB, enabling the frame 150 to be grasped by a user from the front of the plate 70. As will be seen hereinafter, by pulling the lamp housing frame 150, utilizing the fingernail grooves 296, a user can detach the entire lamp subassembly 76 from the switch subassembly mounting retainers 114, 116. Additionally, the fingernail grooves 296 facilitate the detachment of the frame 150 from the lamp housing 157. That is, by grasping the frame 150 with the fingernails of one hand in the grooves 296, a user can utilize the fingers of his other hand to pull on the retainer pins 156. In this way, the user can lift frame 150 off housing 157 to expose the cavity 210 and thereby provide access to bulb 250 enabling it to be readily replaced. Attention is now directed primarily to Figure 6 which illustrates an exploded view of the switch subassembly 74. The switch subassembly includes the aforementioned switch housing 100 which is substantially planar in form and rectangular in shape. The housing 100 is essentially comprised of a center section 300 which contains the aforementioned internal cavity 101 for accommodating the aforementioned switch and tactile feedback mechanism 102. The section 300 includes first and second side walls 302 and 304. Outer walls 306 and 308 are respectively spaced from the side walls 302 and 304 to respectively define therebetween the aforementioned guide channels 110, 112 for accommodating the mounting retainers 114, 116. -12- The mounting retainers 114 and 116 are mirror images of one another and each is configured to fit within one of the guide channels 110,112 for sliding movement therein. More particularly, each of the mounting retainers 114, 116 comprises an elongated member having an upper surface 310 having a pair of closely spaced opposed jaws 312, 314 extending therefrom. The mounting retainers 114, 116 preferably comprise molded plastic parts of appropriate material to enable the extending jaws 312 and 314 to flex resiliently outward slightly to enable the aforementioned retainer pins 156 to press past the inwardly extending opposed jaw ends 318. Each mounting retainer 114, 116 also includes first and second recesses 330 and 332 for respectively accommodating the upper ends of coil springs 334 and 336. The lower end of coil spring 334 fits over and is retained on stud 340 formed in- the floor of a guide channel 110, 112, as is best depicted in Figure 8. The lower end of coil spring 336 fits around and is electrically coupled to female connector 346, as is also best illustrated by Figure 8. Connector 346 comprises one of " the female end connectors 104 previously mentioned in the description of Figure 2. Connector 346 physically accommodates and is electrically connected to one of the conductive pins 106 affixed to the aforementioned circuit board 60. Outer walls 306, 308 define a tab slot 350 for receiving a tab 352 formed along the outer edge of each mounting retainer 114, 116. When properly assembled, the mounting retainers 114, 116 are respectively accommodated in guide channel 110, 112 with the tabs 352 extending outwardly through the slots 350 and with the retainers supported on springs 334 and 336. Thus, the retainers 114, 116 are able to exhibit limited resilient and reciprocal movement within the channels in the direction represented by arrows 360 in Figure 8. -13- In accordance with a significant feature of the invention, in order to complete the electrical path to bulb 250, each spring 336 is formed, as depicted in Figure 8, with a cantilevered arm 364 extending from its upper coil. More particularly, the arm 364 is preferably integrally formed with the end coil of the spring 336 and terminates in a U-shaped contact 366 positioned to engage one of the contact pads 240, 242 on the under side of the lamp assembly circuit board 220. When the lamp subassembly is properly mounted on the retainers . 114, 116 with each pin 156 seated on an arcuate surface - 322, each contact pad, e.g. 242 will engage the U-shaped terminal contact 366 of a cantilevered spring arm 364. The arm 364 is essentially rigid such that it primarily flexes around a line through the axis of coil spring 336. In this manner, the terminal contact 366 and contact pad 242 • form a good low ' resistance nonwearing contact interface which, nevertheless, permits . easy detachment and replacement of the lamp subassembly 76. When the lamp subassembly 76 is properly mounted in the mounting retainers 114, 116, the bottom surface 230 of the circuit board 220 engages the aforementioned plunger 134 of the switch subassembly 74. Plunger 134 is mounted for reciprocal movement within the central opening 132 of the cover plate 130. The plunger 134 preferably comprises an integral device having an upper portion including a head 400 and a flange 402 spaced therefrom. .. The head 400 extends above cover plate 130 and flange 402 is supported within opening 132 extending into boss 404 depending from the cover plate 130 (Figure 10). An O-ring 406 is carried between the head 400 and flange 402 to seal opening 132. The lower portion of the plunger 134 includes a shaft 408 which extends through a central opening of an actuator member 412. The shaft 408 is secured to actuator member 412 , as by lock washer 414. Thus, -14- plunger 134 and actuator member 412 are essentially locked together so that finger pressure applied to the lamp subassembly 76 translucent chip 164 displaces plunger 134 and actuator member 412, i.e. as depicted by arrows 420 in Figure 10. Figure 10 depicts the actuator member 412 in its quiescent upper position. Figure 12 depicts the actuator member 412 in its depressed lower position. As will be seen hereinafter, the actuator member 412 controls a switching mechanism such that the switch is normally open when the actuator member 412 is in its quiescent position (Figure 10) and is closed when the actuator member 412 is in its depressed position (Figure 12). The aforementioned switch and tactile feedback mechanism 102 is comprised of two portions; namely, a switch portion 421 and a tactile feedback portion 422 (Figure 9). The switch portion 421 includes switch contacts 424, 426 which are mounted within the housing recess 101 so that they are aligned with and overlay a guide groove 430. The switch contacts 424, 426 include terminal portions 432, 434 which connect electrically to female connectors 440, 442, i.e. the two central connectors of previously referred to connectors 104 in Figure 2. Connectors 440, 442 are mounted with connector positioning holes 444 in housing 100. The switch portion 420 further includes an electrically conductive member 448, preferably a gold plated ball, mounted for linear displacement with the guide groove 430 under the urging of a coil spring 450. In the absence of any interference, the spring 450 urges the ball 448 into engagement with the contact 424, 426 to thus electrically connect connectors 440 and 442. The actuator member 412 is shaped so that when in its quiescent position (Figure 10) it interferes with the ball 448 and blocks it from electrically bridging contacts 424, 426. When depressed, the -15- actuator member moves out of the way to permit the spring 450 to displace the ball 448 into engagement with the contacts 424, 426. More particularly, the actuator member 412 includes a radially extending projection 460 including a ramp portion 462 and end portion 464. Note in Figure 10 that the end portion 464 of the projection 460 extends through the gap between the spaced contacts 424, 426 to engage the ball 448 to block it from engaging contacts 424, 426. When the actuator member 412 is depressed, as depicted in Figure 12, the projection end 464 moves out of interfering relationship to thereby permit the ball to move into bridging contact against contacts 424, 426. The utilization of a conductive ball 448 mounted for linear displacement in the manner depicted in the drawings for selectively bridging contacts 424, 426 assures a low resistance, high reliability and easily fabricated switch mechanism. The tactile feedback portion 422 functions to develop a reaction force to indicate to a user when switch closure has occurred. More particularly, as a user depresses the lamp subassembly 76 toward switch closure, it is desirable for the user to experience a reaction force which increases as the actuator is displaced toward the toggle point and then abruptly diminishes as the switch is closed to thus provide a "snap" feel. This tactile feedback is provided in accordance with the preferred embodiment by elements 470, 472, 474, and 476 which cooperate with a wedge or inclined surface 478 formed on actuator member 412. More particularly, as is best depicted in Figures 9 and 11, element 476 comprises a rocker arm including a rolling pivot portion 479 and an upper surface 480. By applying an appropriate downward force (e.g. in the plane of Figure 9) against the surface 480, the rocker 476 can be caused to rock around the rolling pivot 479, mounted for rolling movement in recess 482 in the -16- housing 100. This force is supplied against the surface 480 by a pusher member or plunger 474 having a lower surface 486 which bears against the surface 480 of rocker arm 476 for sliding movement therealong. The plunger 474 is urged against the rocker surface 480 by spring 472 which is held captive between plunger 474 and toggle arm 470. Toggle arm 470 is shaped to define a rolling pivot 490 which is accommodated in a mating recess 492 in housing 100. Toggle arm 470 is provided with an inclined surface 500 mounted for engagement against -inclined surface 478 of actuator member 412. When the actuator member 412 is in the quiescent position depicted in Figure 10, the toggle arm 470 will be in its quiescent position established by the spring 472 bearing against plunger 474 to force the rocker arm 476 to its clockwise position as depicted in Figure 9. As the lamp subassembly 76.is depressed to displace the actuator member 412 toward its actuated position depicted in Figure 12, the actuator member inclined surface 478 bears against the inclined surface 500 of the toggle arm to rotate it about its rolling pivot 490 within recess 492. This, of course, slides plunger surface 486 along surface 480 of rocker arm 476. As the surface 486 moves toward a threshold or center position essentially defined by a straight line projected between the axes of rolling pivots 478 and 490, the compression of spring 472, thereby providing an increasing reaction force, via the actuating member 412 to the user pressing the lamp subassembly 76. However, once the surface 486 of plunger 474 moves past the center position, the rocker arm 480 is toggled to its counter clockwise position (Figure 11) thereby enabling the spring 472 to expand and abruptly diminish the reaction force felt by the user. When the user releases the lamp subassembly 76, the springs 334, 336 will lift the mounting retainers 114, 116 thus relieving the downward force on actuator -17- member 412. The spring 472, still under compression in the position depicted in Figure 11, will want to expand and thus will slide surface 486 along rocker arm surface 480 as it pivots the toggle arm 470 clockwise toward the orientation of Figure 9. As the toggle arm 470 returns to the orientation of Figure 9, its inclined surface 500 will bear against inclined surface 478 to lift the actuator member 412 to its quiescent position with projection 460 bearing against ball 448 to open the switch. From the foregoing, it should now be appreciated that an improved push button switch module has been described herein comprised essentially of a switch subassembly intended to be physically and electrically mounted on a circuit board and a lamp subassembly intended to be detachably mounted on the switch subassembly. A module in accordance with the invention can be accommodated in a very small package occupying, for example, only about a one quarter square inch area (1/2 inch square) on the circuit board. The full vertical or depth dimension of the module can also be accommodated in less than one half inch with the switch subassembly housing comprising about one half of that dimension. Thus, the circuit board 60 and cover plate 70 can be very closely spaced, i.e. within about one quarter inch of each other. Despite these small dimensions, the lamp subassembly configuration enables a single lamp to provide ample uniform back lighting of a translucent chip, as a consequence of the optimized reflector, and enables a user to readily replace the lamp from the front of the plate 70 using only his fingers. The switch subassembly configuration assures good tactile feedback and good low resistance low bounce switching within a low profile package. Although a particular exemplary embodiment has been described and illustrated herein, it is recognized that numerous modifications and variations falling -18- within the intended scope of the invention may readily occur to those skilled in the art. For example only, light sources other than incandescent bulbs, e.g. light emitting diodes, can be employed. As a further example, the cantilevered contact arms 364 for providing electrical connection to the movably mounted lamp subassembly can comprise separate elements rather than be integral with springs 336. As a still further example, the movable contact member 448 can be other than ball shaped and the tactile feedback mechanism 102 can utilize a linearly displaceable member rather than the pivotally mounted toggle arm 470. In view of the foregoing, it is intended that the appended claims be liberally interpreted to cover all reasonable modifications and variations.

Claims: CLAIMS 1. An illuminated push button switch module comprising: a switch subassembly including a switch actuator 5 mounted for limited reciprocal displacement; a lamp subassembly having at least one electrically energizable light source and at least one electrical contact pad connected to said light source; mounting means supporting said lamp subassembly - 10 for -reciprocal displacement toward and away from said switch subassembly for displacing said switch actuator in response to said lamp subassembly being displaced; means attaching said lamp subassembly to said mounting means for permitting detachment without the 15 use of tools; and electrical contact means carried by said switch subassembly for engaging said contact pad when said lamp subassembly is retained on said mounting means. 2. The module of claim 1 wherein said contact 20 means comprises a contact terminally carried by a resiliently mounted cantilevered arm. 3. The module of claim 1 wherein said switch subassembly and said lamp subassembly include substantially flat housings oriented parallel to one 25 another; and wherein said mounting means includes spring; means supporting said lamp subassembly housing for resilient displacement relative to said switch subassembly housing. 30 4. The module of claim 3 wherein said spring means includes at least one coil spring formed of electrically conductive material and having an axis oriented substantially perpendicular to said flat housings; and wherein -20- said contact means includes a cantilevered arm extending from an end coil of said coil spring 5. The module of claim 1 including a circuit board; and means electrically connecting said switch subassembly to said circuit board. 6. The module of claim 5 wherein said switch subassembly has a larger perimeter than said lamp subassembly; and a plate having front and rear faces and an aperture therein large enough to pass said lamp subassembly therethrough; and means mounting said plate with said rear face bearing against said switch subassembly to clamp it against said circuit board. 7. The module of claim 5 wherein said means electrically connecting said switch subassembly to said circuit board includes: at least one male connector mounted on said circuit board; and further including: female connector means carried by said switch subassembly for physically receiving said male connector therein. 8. The module of claim 7 wherein said switch subassembly has a larger perimeter than said lamp subassembly; and a plate having front and rear faces and an aperture therein large enough to pass said lamp subassembly therethrough; and means mounting said plate with said rear face bearing against said switch subassembly to clamp it against said circuit board. 9. The module of claim 1 wherein said mounting -21- means includes a first retainer member; and spring means supporting-said retainer member for reciprocal displacement relative to said switch subassembly. 10. The module of claim 9 wherein said means for releasably retaining said lamp subassembly includes: a retainer pin fixedly mounted on said lamp subassembly; and detent means mounted on said retainer member for • receiving and releasably retaining said retainer pin. 11. The module of claim 10 wherein said detent means comprises first and second spaced jaw members mounted for resilient movement relative to one another for receiving said retainer pin therebetween. 12. The ' module of claim 10 wherein- said lamp subassembly includes a finger nail groove therein for enabling a user to pull the lamp subassembly away from the switch subassembly to release said retainer pin from said detent means. 13. The module of claim 9 further including: guide wall means mounted on said switch subassembly for engaging said retainer member to guide said retainer member reciprocal displacement relative to said switch subassembly. 14. An electric switch comprising: first and second conductive contact pads spaced from one another in a common plane; a conductive contact member; guide means supporting said contact member for displacement along a path extending substantially perpendicular to said common plane between first and second positions respectively in and out of bridging -22- contact with said first and second contact pads; spring means engaging said contact member for moving it to a certain one of said positions; actuator means; and means mounting said actuator means for selective movement between a first noninterfering orientation enabling said spring means to position said contact member at said certain position and a second interfering orientation for positioning said contact member at the other of said positions. 15. The switch of claim 14 wherein said guide means includes a linear groove; and wherein said conductive member comprises a ball supported in said groove for reciprocal movement therealong. 16. The switch of claim 15 wherein said spring means comprises a coil spring having an .axis oriented parallel to said linear groove. 1 17. The switch of claim 14 wherein said actuator means comprises a plunger formed of non conductive material and mounted for reciprocal linear movement, in a direction substantially perpendicular to said path, between said first and second orientations; said plunger having a boss extending laterally therefrom for engaging said contact member when said plunger assumes said second orientation. 18. A push button electric switch comprising: first and second conductive contacts; an actuator mounted for displacement from a quiescent position through an active position to an end position; means responsive to said actuator reaching said active position for electrically connecting said first and second contacts; and -23- tactile feedback means coupled to said actuator for imposing on said actuator an increasing reaction force for a first increment of actuator displacement between said quiescent position and said active position and a decreasing reaction force for a second increment of actuator displacement between said active position and said end position; said tactile feedback means including: a rocker arm supported for rocking motion about a rocker axis between first and second states; pusher means bearing against said rocker arm; and means coupling said actuator to said pusher means for forcing said rocker arm to said first state during said first increment of actuator displacement and to said second state during said second increment of actuator displacement. 19. The switch of claim 18 wherein said means coupling said actuator to said pusher means includes means for displacing said pusher means along said rocker arm substantially proportionally to the displacement of said actuator. 20. The switch of claim 19 wherein said means for displacing said pusher means includes a toggle arm mounted for pivotal motion about a pivot axis extending substantially parallel to and spaced from said rocker axis. 21. The switch of claim 20 wherein said pusher means comprises: a plunger having an end surface; and means coupling said plunger to said toggle arm for resiliently pushing said plunger end surface against said rocker arm and for translating said plunger along said rocker arm as said toggle arm pivots. -24- 22. The switch of claim 21 wherein said actuator and said toggle arm respectively have first and second inclined surfaces mated to one another; and means mounting said actuator for linear displacement along a path oriented substantially parallel to said toggle arm pivot axis whereby displacement of said actuator pivots said toggle about said pivot axis. 23. A low profile lamp assembly comprising: a flat translucent chip having front and rear faces; reflector means comprising a substantially concave parabolic surface truncated by a flat surface, said parabolic surface and said flat surface being highly and substantially uniformly reflective; diffraction grating means comprising a plurality of fine grooves formed on said flat surface; means mounting said reflector means close to said translucent chip with said flat surface oriented substantially parallel to and spaced from said chip rear face; a lamp having an energizable illumination means therein; and means mounting said lamp between said translucent chip rear face and said reflector means whereby said illumination means will illuminate said parabolic and flat surfaces to reflect light onto said chip rear face. 24. The lamp assembly of claim 23 wherein said fine grooves are arranged in a radiating spoke pattern. 25. The lamp assembly of claim 23 wherein said lamp comprises an incandescent bulb having a transparent envelope and said illumination means -25- σomprises a filament mounted in said envelope; and wherein said bulb is mounted to orient the plane of said filament substantially parallel to said reflector means flat surface. 26. The lamp assembly of claim 25 including diffuser means mounted on said bulb envelope between said filament and said translucent chip rear face for preventing the formation of a bright spot by said filament as viewed from the front face of said translucent chip. 27. A low profile lamp assembly for use in an illuminable display, said lamp, assembly comprising: a flat translucent chip having front and rear faces; energizable light source- means mounted proximate to said translucent chip rear face; and reflector means mounted proximate to said light source means remote from said translucent chip for reflecting a substantially uniform field of light onto said chip rear face; said reflector means defining a cavity opening toward said light source means, said cavity having an internal surface including a flat end surface extending substantially parallel to said translucent chip and a truncated substantially parabolic portion surrounding said flat end surface; and diffraction grating means comprising a plurality of closely spaced fine grooves formed in said end surface opposite to said chip rear face. 28. The lamp assembly of claim 27 wherein said plurality of fine grooves extend in a radial pattern. 29. The lamp assembly of claim 27 wherein said end surface is metallized and highly reflective. 30. The lamp assembly of claim 27 wherein said light source means comprises an incandescent bulb having a transparent envelope and a filament therein; and means mounting said bulb with said filament oriented substantially parallel to said reflector means end surface. 31. The lamp assembly of claim 30 including diffuser means mounted on said bulb envelope between said filament and said translucent chip for preventing the formation of a bright spot by said filament as viewed from the front face of said translucent chip. 32. The lamp assembly of claim 27 wherein said reflector means includes a housing defining said cavity therein; and further including: a frame defining a window area; and means for releasably retaining said translucent chip and said housing in said frame with chip disposed in said window area. 33. The lamp assembly of claim 32 wherein said housing includes a pin extending therefrom; and wherein said frame includes a slot for receiving said pin to releasably retain together said frame and said housing. 34. The lamp assembly of claim 33 wherein said slot includes a detent pocket for accommodating said pin. 35. The lamp assembly of claim 34 wherein said frame includes a fingernail groove therein for facilitating removal of said housing from said frame. -27- 36. The lamp assembly of claim 27 wherein said flat end surface is formed by a disk mounted in an opening in said cavity internal surface. 37. The lamp assembly of claim 36 further including a circuit board supported adjacent to said housing; an access opening in said cavity internal surface; and wherein said light source has leads extending through said access opening and connected to said circuit board.

Inventors: SCHLOSSER MARK S, SCHLOSSER, MARK, S.
Applicants: BELL IND INC, BELL INDUSTRIES, INC.
Application year: 1986
Main classification: H01H3
IPC codes: H01H1, H01H9, H01H13