WO1985002938A1

WO1985002938A1 - Push button switch and pilot light

Info

Publication number: WO1985002938A1
Application number: PCT/US1983/002029
Authority: WO
Inventors: Frank J. Graninger; Gary C. Fillus; Roger E. Karweik
Original assignee: Allen-Bradley Company
Priority date: 1983-12-21
Filing date: 1983-12-21
Publication date: 1985-07-04
Also published as: EP0168386A1; BR8307764A; JPS61500993A

Abstract

An illuminated push button switch comprises a mounting barrel (24) having a lamp socket (44) inserted partially into the rearward end of the barrel. A spring biased plunger assembly (22), is comprised of a lens cap (126) and a plunger (104) releasably mounted thereto. The plunger (104) is inserted into the forward end of the barrel (24) so that the plunger (104) extends through the lamp socket (44) for actuating a contact block (20) attached to the rear of the lamp socket (44). A set of cammed webs (118a, 118b) extend radially inwardly into the bore of the plunger (104) for urging the bulb (56), telescoped into the plunger (104) in engagement with the lamp socket (44), out of such engagement upon partial withdrawal of the plunger (104). The forward end of the mounting barrel (24) is provided with a lip (26) having locking grooves (28) for releasably engaging the fingers (30) of a bezel (34) dimensioned to receive the head (126a) of the lens cap (126). The releasable engagement of the bezel (34) with the mounting barrel lip (26) allows differing size bezels to be utilized to allow great flexibility with reduced manufacturing costs. The switch may also be easily converted into a pilot light using the same components, thereby effecting a manufacturing savings.

Description

PUSH BUTTON SWITCH AND PILOT LIGHT

Field of the Invention This invention relates generally to switches and pilot lights and more particularly to an illuminated push button switch which may also be configured as a pilot light.

Background Art Push button switches are commonly found in many different types of electrical equipment for making or breaking an electrical circuit so as to control an electrical device. Often, push button switches are constructed to include a bulb which is typically illuminated to prompt the human observer to actuate the switch by tactile contact. Alternatively, the lamp of the switch may be illuminated responsive to tactile contact by tne human observer to indicate switch actuation. Such types of push button switches are commonly known as illuminated push button switches and are well known in the art.

Present day commercially available, illuminated push button switches are generally differentiated by the physical size of the switch and the current handling capability of the switch. Thus " large" switches are both physically bigger and carry more current than "small" switches. In the past, large switches have been constructed of modular sub-assemblies whereas small switches have been constructed of a single integral body. Present day small illuminated push button switches, although generally satisfactory for most applications, are nevertheless believed to possess several disadvantages. For instance, most small illuminated push button switches are manufactured of a single molded switch body having an integral switch bezel. Different applications for small illuminated push button switches may require different bezel sizes. In order to meet the demand for different bezel sizes, a manufacturer may need to have several different molds in order to manufacture push button switches having the desired bezel size. The disadvantage which is believed to be incurred by molding the switch body as an integral unit is that certain sacrifices must be made in the design of the switch body and in selecting the materials used to mold the switch body.

Another disadvantage attributable to present day small illuminated push button switches is the lack of an effective sealing mechanism for sealing the opening between the switch body and the mounting panel. In many industrial environments, the switch is exposed to contaminants and without an effective seal between switch and the panel opening, contaminants can enter the panel opening and run down the body of the switch. The problem of contaminants entering through the panel opening is also incurred by many small-size pilot lights as well because of the lack of an effective seal between the pilot light body and the panel opening.

Yet another disadvantage which is believed attributable to present day small illuminated push button switches as well as pilot lights is the difficulty incurred in replacing the bulb should the bulb burn out. In most cases, bulb extraction requires the use of a separate member to grip the bulb and remove it from the body of the switch or pilot light. Such an extraction tool is often not readily available when the bulb burns out, thereby delaying bulb replacement. Brief Summary of the Invention The present invention relates to a modular assembly having interchangeable components which allows fabrication of different push button switches and pilot lights without significantly increasing manufacturing costs. In accordance with the preferred embodiment, there is provided an improved push button switch comprised of a mounting barrel having a lamp socket partially received into the rearward end of the mounting barrel so that the bulbreceiving opening in the socket is within the mounting barrel. A plunger assembly having a light diffusing head and an actuating end is received in the forward end of the barrel so that the actuating end extends through the barrel to contact the actuating member of a contact block attached to the end of the lamp socket extending from the barrel. The plunger assembly head serves to diffuse the light radiated by the bulb held in the lamp socket as well as to transmit the force of a human operator to the actuating member of the contact block. Typically, the plunger assembly comprises a plunger telescoped into the mounting barrel so as to extend through the lamp socket for engaging the actuating member of the contact block. Concentric within the plunger is the bulb which is exposed through an opening in the rearward end of the plunger to engage the lamp socket. The plunger is advantageously provided with a pair of cammed webs which extend radially inwardly from the bore of the plunger to urge the bulb out of engagement with the socket upon forward movement of the plunger beyond its forward position of travel during switch operation. To actuate the plunger, a light diffusing lens cap has its stem partially telescoped with the mounting barrel for releasable engagement with the plunger. A bezel, having an opening sized to receive the head of the lens cap, is releasably secured to a lip at the forward end of the mounting barrel upon engagement of the bayonet fingers on the bezel with the bayonet locking grooves on the barrel lip. The releasable engagement of the lens cap with the plunger and the releasable bayonet locking engagement of the bezel with the lip on the mounting barrel allows differing size bezels and lens caps to be utilized with the modular push button switch assembly components comprised of the mounting barrel, the lamp socket and the contact block.

To prevent the entry of foreign substances, and particularly corrosive materials into opening between the mounting panel and the switch mounting barrel, a gasket is carried on the forward end of the mounting barrel adjacent to the mounting barrel lip to seal the opening between the lip and the bezel. The gasket may be advantageously provided with a set of projecting bosses for engaging the bezel bayonet fingers so as to impede rotation of the bezel once the bezel engages the lip of the mounting barrel. Additionally, the gasket provides a snug fit between the mounting barrel and the panel opening to allow the push button switch to be held in the mounting panel prior to threading of a fastener about the mounting barrel to secure the switch to the panel.

The modular construction of the switch allows a pilot light and a non-illuminated push button switch to be fabricated using most of the same components. The deletion of the contact block and the addition of a band about the plunger to maintain the plunger in a fixed position converts the above-described switch into a pilot lamp. Alternatively, by simply deleting the bulb, the illuminated push button switch can be converted into a non-illuminated push button switch.

It is an object of the present invention to provide an improved illuminated push button switch which may be configured in various arrangements without significantly adding to the manufacturing cost of the switch. The releasable engagement of the switch bezel with the mounting barrel of the switch assembly and the releasable engagement of the lens cap with the switch plunger allows differing size bezels and lens caps to be utilized with either the switch or a pilot light.

It is yet another object of the present invention to provide an improved illuminated push button switch and pilot light whose bulb may be automatically extracted without the need for a separate bulb extracting apparatus. By providing the plunger with cammed radially inwardly extending webs in engagement with the bulb, the bulb is automatically forced from the lamp socket upon forward movement of the plunger beyond its forward position of travel so as to eliminate the necessity for a separate bulb extraction apparatus to remove the bulb.

It is yet another object of the present invention to provide an improved illuminated push button switch and pilot light which is provided with an improved gasket for preventing the entry of foreign materials into the opening between the mounting barrel.of the switch or pilot light and the mounting panel. By providing a gasket about the mounting barrel concentric with the panel opening, and adjacent to the bezel, the gasket provides an axial seal with the bezel and a radial seal about the mounting panel opening. Also, by providing the gasket with forwardly projecting bosses in engagement with the bezel, the gasket also impedes the bezel from rotating which is very advantageous.

It is yet another object of the present invention to provide a push button switch comprised of a modular assembly whose parts can also be used to fabricate a pilot light. By deleting the contact block and by adding a band about the plunger to keep the plunger stationary, the push button switch can be converted into a pilot light.

Brief Description of the Drawings Fig. 1 is an exploded perspective view of the improved illuminated push button switch of the present invention; Fig. 2 is a cross-sectional view of the switch of Fig. 1 taken along lines 2-2 of Fig. 1;

Fig. 3 is a cross-sectional view of the illuminated push button switch of Fig. 1 taken along lines 3-3 of Fig. 1;

Fig. 4 is a cross-sectional view taken along lines 4-4 of Fig. 1 illustrating the engagement of the lamp socket base fingers with the mounting barrel;

Fig. 5 is a cross-sectional view of the illuminated push button switch of Fig. 1 taken along lines 5-5 of Fig. 1;

Fig. 6 is a cross-sectional view of the push button switch assembly similar to Fig. 5 except that the mounting barrel has been rotated counterclockwise (with respectto the axis of the switch illustrated in Fig. 1);

Fig. 7 is a cross-sectional view taken along lines 7-7 of Fig. 6 illustrating the details of how the switch bezel engages the mounting barrel;

Fig. 8 is an exploded perspective view of the contact block of the improved push button switch of Fig. 1;

Fig. 9 is a view of the contact block taken along lines 9-9 of Fig. 8;

Fig. 10 is a cross-sectional view of the contact block of Fig. 9 taken along lines 10-10 thereof; and Fig. 11 is a side elevational view of the ram of the plunger assembly of the push button switch of Fig. 1 rotated 90 degrees from the position of the ram illustrated in Fig. 1.

Detailed Description of the Preferred Embodiment Figure 1 illustrates an improved illuminated push button switch 14 constructed in accordance with the teachings of the present invention. Switch 14 is modular in construction and is comprised of a mounting assembly 16, a lamp socket 18 partially inserted in the rearward end of the mounting assembly 16, a contact block 20 attached to the end of the lamp socket 18 extending from the mounting assembly, and a plunger assembly 22 received in the forward end of the mounting assembly 16 and extending at least partially through the lamp socket 18 for actuating the contacts of the contact block 20. The designations forward end and rearward end designate the leftward and rightward ends of the elements as illustrated in Fig. 1.

Referring to Fig. 1, the mounting assembly 16 includes a mounting barrel 24 which typically takes the form of a cylindrical sleeve manufactured of zinc or the like. The mounting barrel 24 is provided with an annular lip 26 about the forward end of the mounting barrel 24. As will become better understood hereinafter by latter reference to Figs. 5, 6 and 7, the lip 26 at the forward end of the mounting barrel 24 is provided with a plurality of "L"-shaped locking grooves 28 (only two of which are illustrated in Fig. 1) for engaging a correspondingone of the radially inwardly extending fingers 30 (Fig. 1) about the central bore 32 (Fig. 1) of the bezel 34. As will become better understood, by reference to Figs. 5 and 6, each "L"-shaped groove 28 has an axially extending portion 28a (Figs. 5 and 6), and a circumferential portion 28b (Figs. 5 and 6) .

Referring to Fig. 1, to seal the opening between the bezel 34 and the mounting barrel 24 once the bezel 34 is releasably secured to the mounting barrel lip 26, a gasket 36 is provided. Turning now to Figures 2 and 3, the gasket 36 is carried concentric about the mounting barrel 24 adjacent to the lip 26. When the gasket 36 is slipped on the mounting barrel 24 to abut the lip 26, the gasket 36 prevents the entry of foreign material through the opening between the mounting barrel 24 and the bezel 34 after the mounting barrel 24 is received in the panel opening. The gasket 36 provides not only an axial seal against the bezel 34, but also provides a radial seal against the opening in a mounting panel (described later). It is this radial seal provided by gasket 36 that allows the mounting barrel 24 to be retained in the opening of the mounting panel after insertion of the mounting barrel 24 into the opening and prior to the mounting barrel 24 being secured to the panel in the manner described hereinafter. Because of the good axial seal provided by gasket 36, it is desirable to provide the back of bezel 34 with radial drain passages 39 (Fig. 1) to allow any fluid entering the bezel through the bezel bore 32 to drain away from the bezel. Referring still to Figure 1, the mounting barrel 24 carries a set of threads for threadedly engaging the threads about the interior periphery of a castle nut 40. As illustrated in Figs. 2 and 3, the castle nut 40 is threaded onto the mounting barrel 24 to secure the mounting barrel 24 and hence the switch 14 through the opening in a mounting panel 42. When the castle nut 40 is threaded onto the mounting barrel 24, the castle nut 40 bears against the undersurface of the panel 42 to deform the gasket 36 axially against the top panel surface and radially against the walls of the mounting panel opening thereby assuring a good seal between the mounting panel 42 and the mounting barrel 24.

Referring back to Figure 1, the lamp socket 18 of the illuminated push button switch 14 includes a socket base 44 which is formed of a substantially solid nonconductive cylinder whose outer diameter is approximately equal to that of the outer diameter of the mounting barrel 24. The socket base 44 has two pairs of diametrically opposed, arcuate fingers 46 (only one pair shown in Fig. 1) which extend forwardly, parallel to the longitudinal axis of the socket base 44. The distance between the opposing fingers of each pair is less than the inner diameter of the bore through the mounting barrel 24. In this way, the fingers 46 can be received in the rearward end of the mounting barrel 24 to ride along the inside bore of the mounting barrel 24, when the socket base 44 is partially inserted into the rearward mounting barrel end (the rightward mounting barrel end as illustrated in Figs. 2 and 3) .

Turning now to both Figs. 1 and 4, each of the fingers 46 has an outwardly projecting nub 48 which is received within an associated opening 50 in the mounting barrel 24. As illustrated in Fig. 4, a set of ramps 52 (only one being illustrated) are each provided in the bore of mounting barrel 26 rearwardly (leftwardly in Fig. 4) from a corresponding one of openings 50 to assure that the nub 48 on each finger 46 is guided along each ramp 52 into the opening 50. In this way, an "interference fit" is obtained between the socket base fingers 46 and the mounting barrel 24.

Referring to Figs. 1, 2 and 3, the lamp socket base 44 has a first pair of arcuate, spaced apart, forwardly extending, opposing walls 54a and 54d (illustrated in Fig. 3) and a second pair of arcuate, spaced apart opposing walls 54b and 54c (illustrated in Figure 2) which lie within the circular area bounded by fingers 46. The walls 54a and 54d and 54b and 54c of each pair are spaced apart a distance slightly greater than the thickness of the base of a miniature type bulb 56. Typically, the bulb 56 comprises an ANSI #85 type miniature bulb as are commercially available. The spacing between each wall of each pair of walls and the opposing wall of the other pair of walls, such as walls 54b of Fig. 2 and 54d of Fig. 3, is slightly greater than the width of the base of the bulb 56 so that the bulb may be received in the recess bounded by the walls 54a-54d. Contact with each of the conductive leads 57 (Fig. 2) on the base of the bulb 56 is accomplished by each of a pair of bulb contactors 58a and 58b illustrated in Fig. 1. As illustrated in Fig. 3, each bulb contactor, such as bulb contactor 58a, is disposed between the walls of each pair of walls, such as walls 54a and 54d. Turning now to Fig. 1, at the forward end of each of bulb contactor 58a and 58b is a gripping finger 60. As shown in Fig. 3, the gripping finger 60 at the forward end of each bulb contactor, such as bulb contactor 58a, serves to engage the base of the bulb 56 to make contact with one of the conductive leads 57 on the bulb base when the bulb 56 is seated in the recess in the socket base 44 between the walls 54a-54d (only walls 54a and 54d illustrated in Fig. 3).

Turning now to Figs. 2 and 3, each of the bulb contactors 58a and 58b extends rearwardly beyond the socket base 44 and through a corresponding one of passageways 62a and 62b (illustrated in Fig. 8 only) in the contact block 20 so as to project rearwardly therebeyond. In addition to making electrical contact with the bulb 56, the lamp contactors 58a and 58b advantageously facilitate the mounting of contact block 20 to the end of the socket base 44 extending rearwardly from the mounting barrel 24. Once the contactors lamp 58a and 58b are each received through a corresponding one of passageways 62a and 62b of Fig. 8, the contact block 20 may be secured to the rearward end of the socket base 44 by twisting both of the lamp contactors as illustrated in Fig. 3.

As will be recalled from the description of the mounting barrel 24 and the bezel 34 provided with respect to Fig. 1, the bezel 34 is releasably secured to the lip 26 at the forward end of the mounting barrel 24 upon engagement of the bezel fingers 30 in the "L" shaped locking grooves 28 in the mounting barrel lip 26. This may be better understood by reference to Figs. 5, 6 and 7. Turning first to Fig. 5 which is a cross-sectional view of the mounting barrel 24 and bezel 34 taken along lines 5-5 of Fig. 1, to releasably engage the bezel 34 with the mounting barrel lip 26, the mounting barrel lip 26 (Fig. 1) is oriented such that each of the radially inwardly extending bezel fingers 30 is aligned with the axially extending groove portion 28a (Fig. 5) of a cor responding one of the "L"-shaped locking grooves 28 (Fig. 1). Then, the mounting barrel 24 is inserted into the bezel bore 32 (Fig. 1) until the mounting barrel lip 26 abuts a shelf 64 (best illustrated in Figs. 1, 2 and 3) within the bezel bore 32. Thereafter, the mounting barrel 24 is rotated through a short arc, as indicated in Fig. 5. Upon completion of rotation, each bezel finger 30 fully seats in the circumferential groove portion 28b of a corresponding locking groove as best illustrated in Fig. 6. As illustrated in Fig. 7, once each of the bezel fingers 30 is fully received in the circumferential groove portion 28b of a corresponding groove 28, the bezel 34 is prevented from moving axially with respect to the mounting barrel lip 26. As may be appreciated by those skilled in the art, the "L"-shaped locking grooves

28 on the lip 26 of the mounting barrel 24 and the fingers 30 on the bezel 34 form bayonet fingers and bayonet locking grooves, respectively, to achieve a releasable bayonet lock which allows differing size bezels to be releasably secured to the mounting barrel lip 26. Unlike prior push button switches which utilize a single mounting assembly having an integral bezel, the releasable engagement of the bezel 34 with the mounting barrel 24 of the switch 14 of the present invention facilitates manufacture of a switch (as well as a pilot light as described later) having differing size bezels. Although not shown, the forward face of the lip 26 is provided with grooves, having bosses therein for engaging each of an additional pair of bezel fingers (not shown) to achieve a snap or detent action once the bezel has been bayonet locked on to the mounting barrel lip 26.

Turning once again to Fig. 1, to impede the bezel 34 from being rotated in. an opposite direction once the bezel 34 has been releasably secured to the mounting barrel 24 by rotating the bezel 34 in the manner just described with respect to Figs. 5 and 6, the gasket 36 is advantageously provided with forwardly extending bosses 66. The bosses 66 on the gasket 36 are angularly spaced about the periphery of the gasket 36 so that each boss 66 is in alignment with a corresponding axially extending groove portion 28a (Figs. 5 and 6) of a locking groove 28 (Fig. 1) in the mounting barrel lip 26. When the lip 26 of le mounting barrel 24 is inserted into the bore 32 of the bezel 34 so that the bezel fingers 30 each seat in the axial portion of a corresponding locking groove 28, the bezel fingers 30 compress the bosses 66 on the gasket 36. After the bezel 34 is rotated to seat each of the fingers 30 in a circumferential groove portion 28b (Figs. 5 and 6) of a corresponding groove, each of the bosses 66 then springs back to fill the axial groove portion. In this way, each boss 66 acts as a stop for the corresponding bezel finger 30 thereby impeding bezel rotation.

Figure 8 illustrates the details of the contact block 20. Turning to that figure which presents an exploded perspective view of the contact block 20, the contact block 20 includes a pair of contact block housing halves 68a and 68b. The contact block housing halves 68a and 68b are each manufactured from an insulative material such as plastic, and each, housing half is complementary to the other to allow the contact block housing halves 68a and 68b to mate in the manner illustrated in Fig. 1. The contact block housing halves 68a and 68b are retained in mating engagement by twisting the bulb contactors 58a and 58b as illustrated in Fig. 2, once each of the bulb contactors have been inserted through each of the passageways 62a and 62b in the contact block housing halves.

Still referring to Fig. 8, in practice, the contact block 20 embodies a double pole single throw switch and to this end, the contact block 20 of Fig. 8 includes a first pair and second pair of "L"-shaped switch contacts 70a and 70b and 72a and 72b, respectively. Each of the switch contacts 70a and 72a is provided with a contact pad 74 on the lower surface of the right angle flange portion of the switch contact whereas each of the switch contacts 70b and 72b is provided with a contact pad 74 on the upper surface of the right angle flange portion of the switch contact. As illustrated in Fig. 2, the leg of each of the switch contacts, such as switch contacts 70a and 72a, extends beyond the contact block 20. Each switch contact and bulb contactor is provided with an oval passageway 76 at its rearward end to permit a wire conductor (not shown) to be twisted or soldered thereto. When the contact block housing halves 68a and 68b are mated, the switch contacts 70a and 70b and 72a and 72b are each retained within the contact block housing halves so that the switch contacts of each pair, such as switch contacts 72a and 72b illustrated in Fig. 10, are held with the leg portion of the switch contact parallel with each other and the right angle flange portion of the switch contact of each pair opposing the right angle flange portion of the other switch contact. In this way, the contact pad 74 on the switch contact of each pair, such as switch contact 72a overlies the contact pad 74 on the other switch contact of the pair such as switch contact 72b. As illustrated in Fig. 9, the first and second switch contact pairs 70a and 70b, and 72a and 72b, respectively, are spaced a short distance apart and receive a contact yoke 78 therebetween.

Turning now to Figs. 8 and 9, the switch contact yoke 78 typically takes the form of a "Y"-shaped conductive member having pair of parallel, spaced apart legs 78a and 78b. Each of the conductive yoke legs 78a and 78b has an outwardly extending tab 80 for extension between the switch contacts 70a and 70b, and switch contacts 72a and 72b, of the first and second pair of switch contacts, respectively, as illustrated in Fig. 9. The tab 80 on one of the legs 78a and 78b of the conductive yoke 78 makes contact with the conductive pad 74 on one of the switch contacts 70a and 70b and the tab 80 on the other of the yoke legs makes contact with the conductive pad 74 on one of the switch contacts 72a and 72b, respectively, depending on whether the contact yoke has been actuated or not.

Still referring to Fig. 8, the top end of each of the legs 78a and 78b of the conductive yoke 78 is provided with a notch 82. The notch 82 in each of the conductive yoke legs 78a and 78b rides in a "V"-shaped slot 84 in a separate one of the parallel, spaced apart walls 86a and 86b of a channel 88 which, as illustrated in Fig. 9, lies between the switch contact pair 70a and 70b, and 72a and 72b. As best illustrated in Fig. 10, the channel 88 is retained in the recess between the contact block housing halves 68a and 68b when the contact block housing halves are mated.

Turning back to Figs. 8 and 9, the upper end. of each of the walls 86a and 86b of the channel 88 has an integral flange portion 90 for guiding the undersurface of an actuating member 92. The flange portion 90 of each of walls 86a and 86b is highly polished to reduce the wearing of the actuating member 92 as it moves therealong. The actuating member 92 has a projecting end 94 which, as illustrated in Fig. 10 projects through an opening 96 in the contact block housing half 68a. As illustrated in Fig. 10, a spring 97 is interposed between the actuating member 92 and the contact block housing half 68b to yieldably urge the actuating member 92 against the contact block housing half 68a. Turning now to Figs. 8-10 jointly, the actuating member 92 has one end of a tension spring 98 secured thereto by way of a pin 100. The opposite end of the tension spring 98 engages a hook 102 on the leg 78b (Figs. 8 and 9) of the conductive yoke 78. As indicated by the dotted line surrounding the following components: the channel 88, the conductive yoke 78, the spring 98 and actuating member 92, all of these components can be assembled together in the manner previously described independently of the other contact block elements which is very desirable. In addition, once these elements have been assembled, the remaining elements within the contact block 20 can then be assembled independently of the rest of the elements comprising the switch 14.

Referring now to Fig. 10, while no pressure is applied to the projecting end 94 of the actuator 92, the spring 98 biases the conductive yoke 78 so that the yoke completes an electrical circuit between the switch contacts 70a and 72a (only switch contact 72a is illustrated in Fig. 10). Upon the application of pressure to the projecting end 94 of the actuating member 92 to urge the actuating member 92 against spring 97, the actuating member 92 pivots the spring 98. The pivoting of the spring 98 provides an over-center snap action, causing the contact yoke 78 to pivot away from switch contacts 70a and 72a so that the yoke legs move into electrical contact with the switch contacts 70b and 72b (only switch contact 72b is illustrated in Fig. 10). Upon release of the pressure applied to the projecting end 94 of the actuating member 92, the spring 97 biases the actuating member 92 forwardly (leftwardly). In response, the tension spring 98 causes the conductive yoke 78 to pivot, causing the yoke legs to move away from each switch contacts 70b and 72b and move back into contact with the switch contacts 70a and 72a. The actuating member 92 of the contact block 20 of Figs. 8-10 is actuated by the plunger assembly 22 of Fig. 1 as will be better understood following a description of the components comprising the plunger assembly 22. Turning now to Fig. 1, the plunger assembly 22 includes a hollow cylindrical plunger or ram 104 having an annular lip 106 at its forward end. The rearward end of the cylinder portion of the ram 104 is open. The diameter of the lip 106 at the forward end of the ram 104 is slightly smaller than the interior diameter of the bore through the mounting barrel 24, allowing the lip 106 to guide the ram 104 for reciprocal movement within the mounting barrel 24. Before inserting the ram 104 into the forward end of the mounting barrel 24 so that the lip 106 rides along the mounting barrel bore, a compression spring 108 is first telescoped on to the ram 104 so as to be circumjacent thereto. Thereafter the ram 104 is inserted into the forward end of the mounting barrel 24 until the spring 108 abuts a shoulder 109 (Figs. 1, 2 and 4) about the interior of the mounting barrel bore.

Turning now to Fig. 11 which is a top elevational view of the ram 104, a pair of hooks 110a and 110b extend rearwardly from the ram 104 for retaining the ram 110 within the mounting barrel 24 of Fig. 1. Turning back to Fig. 2 for a moment, once the ram 104 has been inserted into the mounting barrel 24, the hooks 110a and 110b (Fig. 11) bear against the shoulder 109 (Figs. 1, 2 and 4) about the bore through the mounting barrel 24. Upon an attempt to withdraw the ram 104, the hooks 110a and

110b engage the shoulder 109 and thus impede the removal of the ram 104 once it has been inserted into the mounting barrel 24.

Turning both to Figs. 1 and 11, the ram 104 is provided with an integral strut 114 which extends rearwardly from the ram body. The strut 114 has an "I"-shaped cross section to increase the strut rigidity as well as to allow the strut 114 to fit between wall 54a and 54d (Fig. 3). and walls 54b and 54c (Fig. 2) of the socket base 44. As illustrated in Fig. 1, the upper flange portion 114a of the strut 114 is longer, that is to say, the upper flange portion 114a extends further rearwardly than the lower flange portion 114b of the strut 114. It is the longer flanged portion 114a of the strut 114 which contacts the projecting end 94 of the actuating member 92 of the contact block 20 of Fig. 8. Turning now to Figures 1 and 2, the strut 114 (illustrated in Fig. 1 only) has a boss 115 on the cross member extending between the flange portions 114a and 114b of Fig. 1. As illustrated in Fig. 2, the boss 115 serves to engage an overhang 116 between walls 54b and

54c to limit the upward travel of the ram 104. Thus, the forward-most position of the ram 104 during normal switch operation is reached when the boss 115 contacts overhang 116 whereas the lower or rearward-most position of the ram is reached when the ram strut contacts the bottom wall of the lamp socket base 44 of Fig. 3.

To enable the flanged portion 114a of the strut 114 to contact the projecting end 94 of the actuating member 92 of the contact block 20, the lamp socket base 44 has a passageway 116 (Fig. 1) therethrough in alignment with the projecting end 94 of the actuating member 92 of the contact.block 20 of Figs. 8-10. During switch 14 assembly, the ram 104 is inserted into the spring 108 and the spring 108 and ram 104 are telescoped into the mounting barrel 24 so that the longer flange portion 114a of the strut 114 is received in the passageway 116 of the socket base 44 in alignment with, and to bear against, the projecting end 94 of the actuating member 92 as illustrated in Fig. 3. In this way, when the ram 104 is yieldably urged into the mounting barrel 24 against spring 108, the longer flange portion 114a of the strut 114 bears against the projecting end 94 of the actuating member 92 of the contact block 20 of Fig. 8.

Referring now to Fig. 1, the strut 114 of the ram 104 has a substantially hollow cross section. The hollow cross section of the strut 114 allows the base of the bulb 56 to be exposed when the bulb 56 is inserted into the forward end of the ram 104 upon assembly of the push button switch 14. With the base of the bulb 56 thus exposed, the base of the bulb 56 is brought into gripping engagement with each gripper 60 at the forward end of each of the bulb contactors 58a and 58b to make electrical contact therewith upon insertion of the ram 104 into the spring 108 and telescoping of the ram 104 and spring 108 into the forward end of the mounting barrel 24 as illustrated in Fig. 3.

Turning now to Fig. 3, the ram 104 has a pair of cammed webs 118a and 118b extending radially inwardly from the interior wall of the bore through ram 104. The webs 118a and 118b are positioned so that when the ram 104 at the forward-most point of its normal travel (that is when boss 115 of Fig. 2 contacts the overhang 116 of Fig. 2), the cammed webs 118a and 118b lie substantially below the envelope of bulb 56. Thus, the cammed webs 118a and 118b of the ram 104 do not interfere with the engagement of the base of the bulb 56 with each gripper 60 of each of the bulb contactors such as bulb contactor 58a during the normal travel of the ram 104. However, when 'the ram 104 is partially withdrawn from the mounting barrel 24, to move the boss 115 of Fig. 2 forwardly (upwardly) of the overhang 116 of Fig. 2, the cammed webs 118a and 118b of Fig. 3 urge the bulb 56 out of engagement with the gripper 60 of each of the bulb contactors. The ram 104 is prevented from being fully withdrawn from the mounting barrel by engagement of the hooks 110a and 110b of Fig. 11, with the shoulder 109 of Figs. 1 and 4. As may now be appreciated, the cammed webs 118a and 118b of the ram 104 serve to extract the bulb 56 from the lamp socket 46, obviating the need for a separate bulb extractor. This facilitates replacement of the bulb 56 after the bulb has burned out.

As described thus far with respect to Fig. 8, the actuation of the contact yoke 78 of the contact block 20 is momentary. Referring to Fig. 1 in order to maintain the electrical circuit between the switch contact 70b and switch contact 72b of Fig. 8 while at the same time breaking the electrical circuit between switch contact 70a and switch contact 72a of Fig. 8, a continuous pressure must be applied against the forward end of ram 104 of Figs. 1 and 11. Once the pressure against the forward end of ram 104 is relieved, the spring 108 of Fig. 1 urges the ram 104 forwardly, and away from the actuating member 92 of Fig. 8 so that the actuating member 92 is urged forwardly by spring 97 (Fig. 10) to pivot spring 98 (Fig. 10) and the contact yoke 78 to its normal rest position against the switch contacts 70a and 72a of Fig. 8.

Referring to Fig. 1, to enable "push-push" operation of switch 14, that is, to enable the switch 14 to remain actuated following the initial application of pressure against the forward end of the ram 104, the switch 14 may be advantageously provided with a locking mechanism which takes the form of a detent wire 120. The detent wire 120 has a hooked end 120a which rides in a groove 122 (Fig. 11) inscribed in the flange portion 114b of the strut 114 of the ram 104 when the detent wire 120 is mounted within the mounting barrel 24 as illustrated in Fig. 3 so that the right angle end 120b of the detent wire 120 is flat against the bottom wall of the socket base 44 and the top wall of contact block 20.

Turning now to Fig. 11, the groove 122 in the flange 114b of strut 114 is typically hour-glass in shape with the forward groove end (the leftward groove end as illustrated in Fig. 11) having a "V"-shaped cross path 124, causing the forward portion of the groove 122 to appear "heart-shaped". When the ram 104 is initially urged inwardly into the spring 108 in the mounting barrel 24 of Fig. 1 against the force of the spring 108, the hooked end 120a of the detent wire 120 (Fig. 1) rides along the walls of the groove 122 (Fig. 11) and ultimately engages the apex of the "V"-shaped cross path 124 (Fig. 11) to lock the ram 104 within the mounting barrel 24. With the ram 104 locked into the mounting barrel 24 against the force of the spring 108, the rearward end of the flange portion 114a (Fig. 1) continuously bears against the projecting end 94 (Fig. 8) of the actuating member 92 (Fig. 8) to keep the contact yoke 78 of Fig. 8 pivoted against the switch contacts 70b and 72b of Fig. 8. Upon the subsequent application of pressure against the ram 104 of Figs. 1 and 11, the hook-shaped end 120a (Fig. 1) of the detent wire 120 falls out of the apex, of the "V"-shaped cross path 124 (Fig. 11) and rides along the sides of the groove 122 (Fig. 11) as the spring 108 of

Fig. 1 urges the ram 104 forwardly. The forward movement of the ram 104 continues until the boss 115 of Fig. 2 bears against the overhang 116 of Fig. 2.

Still referring to Fig. 1, in addition to ram 104, the plunger assembly 22 includes a lens cap 126. The lens cap 126 not only serves to diffuse the light radiated by bulb 56 but also provides a mechanism whereby the tactile pressure of a human member may be transmitted _^to the ram 104 to actuate the actuating member 92 of Fig. 8. In the presently preferred embodiment of switch 14, the lens cap 126 has a head 126a dimensioned to be received within the bezel 34 as illustrated in Figs. 2 and 3, and a rearwardly extending shaft portion 126b (Fig. 1). The diameter of the shaft portion 126b is approximately equal to the diameter of the lip 106 on the ram.104 so that the shaft portion 126b of the lens cap 126 can be received within the bore of the mounting barrel 24 upon switch assembly. A pair of diametrically opposed arcuate hooks 128a and 128b extend rearwardly from the shaft portion 126b of the lens cap 126. The distance between the hooks 128a and 128b is less than the inner diameter of the bore through the ram 104 to enable the hooks 128a and 128b to be inserted into, and received within the forward end of the ram 104. To facilitate engagement of each of the hooks 128a and 128b with the ram 104, the interior bore of ram 104 is provided with a pair of diametrically opposed pockets 130 (only one pocket 130 illustrated in phantom in Fig. 11) for receiving a corresponding one of hooks 128a and 128b of the lens cap 126 of Fig. 1. Each of the hooks 128a and 128b has a radially outwardly projecting nub 132 which is received through a corresponding one of the openings 134 disposed through the ram 104 within the area bounded by each of the pockets 130. In this way, an "interference-fit" is obtained between the hooks 128a and 128b of the lens cap 126 and the ram 104. Although the head 126a of the lens cap 126 is illustrated in Fig. 1 as being rectangular to fit within the rectangular opening in the bezel 34, the lens cap head 126a could be made round, square or any other shape. Accordingly, the shape of the lens cap receiving pocket defined by the bezel walls would be selected complementary to the lens cap. To provide a seal between the lens cap 126 and the mounting barrel 24, the lens cap shaft 126b has a recess therein for receiving a rubber seal 135 (Figs. 2 and 3) . Referring to Fig. 1, in practice, the lens cap 126 is typically manufactured from a transparent, colorless plastic. Although the lens cap 126 could be manufactured from a colored plastic to impart a particular hue to the light passing therethrough from bulb 56, it is generally more desirable to change the hue of the light passing through the lens cap 126 by way of a lens cap cover 136. The lens cap cover 136 is dimensioned to snap over the head 126a of the lens cap 126 and is manufactured of transparent plastic colored to impart the desired hue to the light, diffused through the lens cap head 126a. Alternatively, the lens cap cover 136 could be made opaque in the event that the switch 10 is made non-illuminating by deleting bulb 56.

Turning now to Figs. 2 and 3, it may also be desirable to interpose an indicia-bearing transparent strip 138 between the head 126a of the lens cap 126 and the lens cap cover 136. Typically, the indicia on the transparent strip 138 interposed between the lens cap 126 and the lens cap cover 136 identifies the component or system which is controlled either in whole or in part by the switch 14.

The present invention is primarily directed to a push button switch, and particularly to an illuminated push button switch (although a non-illuminated push button switch can be had by deleting the bulb 56). However, the same modular assembly of components which are utilized to construct the push button switch 14 of Fig. 1 can also be utilized to contruct a pilot lamp, thus effecting a manufacturing savings. Referring to Figure 1 by deleting the contact block 20, the push button switch 14 becomes a pilot light. To avoid the spring action of the ram 104 attributed to the spring 108, the spring 108 would also be deleted, and a band 140 (shown in phantom) would be telescoped onto the ram 104 in place of the spring so as to keep the ram 104 stationary within the bore of the mounting barrel 24.

The pilot light thus obtained would enjoy the same advantages of the previously described push button switch, including the good seal obtained by gasket 36 and the self-ejecting bulb action obtained from cammed webs 118a and 118b on the bore of the ram 104.

While only certain preferred features of the invention have been shown by way of illustration, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

CLAIMS 1. A push button switch comprising: a hollow bore mounting barrel having an annular lip at one end thereof; said lip having a plurality of locking grooves; a bezel having means thereon for releasably engaging said mounting barrel lip; a body partially received within the end of said mounting barrel opposite said lip and extending beyond said mounting barrel, said body haying an axially extending passageway therethrough; a contact block attached to the end of said member extending beyond said mounting barrel, said contact block having an actuating member in communication with said body passageway; a spring-biased plunger received in the end of said mounting barrel having said lip, and said plunger extending through said mounting barrel and into said body passageway for reciprocal travel, from a forward position to a rearward position in engagement with said contact block actuating member; and a lens member received partially within said barrel and releasably attached to said plunger for transmitting the tactile contact force of a human member to said plunger.

2. The invention according to claim 1 wherein said body comprises a lamp socket having a recess therein for receiving a bulb and having a pair of bulb contactors for making electrical contact with said bulb.

3. The invention according to claim 2 wherein said plunger has a bore therethrough and a rearwardly-extending strut having a hollow cross section to enable a bulb, when telescoped within the plunger bore, to be exposed for seating within said lamp socket recess to make contact with said bulb contactors upon insertion of said plunger into said mounting barrel.

4. The invention according to claim 3 wherein said plunger has a plurality of webs extending radially inwardly from the bore through said plunger for engaging said bulb telescoped into said plunger to urge said bulb out of engagement with said lamp socket upon forward movement of said plunger beyond said plunger forward position.

5. The invention according to claim 1 wherein said bezel has an axially extending bore therethrough and wherein said means on said bezel for releasably engaging said grooves in said mounting barrel lip comprise a plurality of bayonet fingers extending radially inwardly from the bezel bore for seating in a corresponding one of said locking grooves in said mounting barrel lip to obtain a releasable bayonet lock therewith.

6. The invention according to claim 1 further including a gasket concentric about said mounting barrel adj acent to said mounting barrel lip for providing a radial and axial seal to seal the opening between said mounting barrel and said bezel and to maintain said mounting barrel in an aperture of a mounting panel.

7. The invention according to claim 6 wherein said gasket includes a plurality of bosses extending forwardly from said ring coaxial with said mounting barrel for engagement with said bezel to impede bezel rotation upon bezel engagement with said mounting barrel lip.

8. The invention according to claim 1 wherein said contact block further includes: an insulative housing; at least two pairs of switch contacts, the contacts of each said pair held in said housing in spaced apart relationship with each other; a contact yoke pivotally mounted in said housing for a movement between a rest position at which said contact yoke makes electrical contact with one of the switch contacts of each pair and an actuated position at which said contact yoke makes electrical contact with the other switch contact of each pair; and means connected between said actuating member and said contact yoke for yieldably biasing said yoke to its rest position and for urging said contact yoke to its actuated position upon actuation of said actuating member.

9. In combination with an illuminated push button switch including a mounting barrel, a lamp socket partially telescoped into the rearward end of said mounting barrel, a contact block appended to the rear of said lamp socket, a hollow plunger telescoped into the forward end of said mounting barrel and extending through said lamp socket to actuate the contact block upon reciprocation of said plunger, and a bulb telescoped into the said plunger so as to extend partially rearwardly therebeyond for seating in said lamp socket, the improvement comprising: at least a pair of cammed webs extending radially into the bore of said plunger for urging the bulb out of engagement with the lamp socket when the plunger is partially withdrawn from the mounting barrel.

10. In combination with an illuminated push button switch including a mounting barrel, a lamp socket partially telescoped into the rearward end of the mounting barrel, a contact block appended to the rearward end of the lamp socket, a plunger telescoped into the mounting barrel and extending through said lamp socket for actuating said contact block, the improvements comprising: a lip about the forward end of said barrel, said lip having a plurality of locking grooves therein; a bezel having means thereon for releasably engaging the locking grooves in said mounting barrel lip; and a gasket concentric about said mounting barrel adjacent to said lip for sealing the opening between said bezel and said lip.

11. The invention according to claim 10 wherein said gasket is provided with forwardly-extending bosses to engage said bezel to impede bezel rotation when said bezel engages said lip.

12. An improved pilot light comprising: a hollow bore mounting barrel having an annular lip at one end thereof, said lip having a plurality of locking grooves; a bezel having means thereon for releasably engaging said locking grooves on said mounting barrel lip; a lamp socket partially received into the end of said mounting barrel opposite said lip and extending beyond said mounting barrel; and a hollow bore plunger received in the end of said mounting barrel having said lip, said plunger having an opening at its end opposite said mounting barrel lip; means telescoped about said plunger for maintaining said plunger at a fixed position within said mounting barrel bore; a bulb telescoped into said plunger so as to be exposed through said plunger opening to make contact with said lamp socket; and a lens member partially received within said barrel and releasably attached to said plunger for diffusing the light radiated by said bulb.

13. The invention according to claim 12 further including a gasket concentric about said mounting barrel adjacent to said mounting barrel lip for providing a radial and axial seal to seal the opening between said mounting barrel and said bezel and to maintain said mounting barrel in an aperture of a mounting panel.

14. The invention according to claim 13 wherein said gasket is provided with forwardly-extending bosses coaxial to said mounting barrel for engaging said bezel when said bezel is releasably secured to said mounting barrel lip to impede bezel rotation.

15. The invention according to claim 12 further including a pair of cammed webs extending radially into the bore of said plunger for contacting said bulb to urge said bulb out of engagement with said lamp socket upon partial withdrawal of said plunger from said mounting barrel.

16. A contact block comprising: an insulative housing; at least two pairs of switch contacts, the contacts of each said pair held in said housing in spaced apart relationship with each other; a contact yoke pivotally mounted in said housing for a movement between a rest position at which said contact yoke makes electrical contact with one of the switch contacts of each pair and an actuated position at which said contact yoke makes electrical contact with the other switch contact of each pair; and means connected between said actuating member and said contact yoke for yieldably biasing said yoke to its rest position and for urging said contact yoke to its actuated position upon actuation of said actuating member.