US3560689A

US3560689A - Pushbutton switch having cam actuated spring contacts also acting as resilient support for pushbutton

Info

Publication number: US3560689A
Application number: US781024A
Authority: US
Inventors: Arthur H Matson
Original assignee: Tektronix Inc
Current assignee: Tektronix Inc
Priority date: 1968-12-04
Filing date: 1968-12-04
Publication date: 1971-02-02
Anticipated expiration: 1988-02-02
Also published as: DE1960979A1; JPS4810983B1

Abstract

A pushbutton switch apparatus having cam actuated spring contacts is described in which such contacts also function as resilient supports on which the pushbutton member is mounted and urged into its normal extended position. The switch contacts are attached directly to a printed circuit board, as is a light bulb which is positioned inside the pushbutton member for illuminating such member. The light bulb is energized by the switch indirectly through a control circuit on the printed circuit board when the pushbutton is depressed to momentarily close the contacts of such switch and the control circuit causes such bulb to remain illuminated until another push button is depressed to change the conductive condition of such circuit.

Description

United States Patent [72] lnventor Arthur H. Matson Portland. Oreg. [2 I] Appli No. 781,024 [22] Filed Dec. 4, 1968 (45] Patented Feb. 2, I971 [73 Assignee Tektronix Inc.

Beaverton, Oreg. a corporation of Oregon [54] PUSIIBUTTON SWITCH HAVING CAM ACTUATED SPRING CONTACTS ALSO ACTING AS RESILIENT SUPPORT FOR PUSl-IBU'ITON 12 Claims, 4 Drawing Figs.

[52] U.S.Cl 200/167 [51] Int.Cl H0lh9/l8 [50] Field of Search ..200/l53.l1, 153.12, 159, 167, 168C; 340/63 [56] References Cited UNITED STATES PATENTS 2,802,082 8/1957 Kalwo 200/167(A)X 2,839,736 6/1958 Tinsley et al 340/63 2.840795 6/1958 Gee 340/63 2,903,540 9/1959 Gloviak et al....

2,956,263 10/1960 Brown et al 340/63 2,994,073 7/1961 Pelovitz 340/63 3,163,740 12/1964 Ross 200/167(A)X 3,251,050 5/1966 Given 1. 200/167(A)X Primary Examiner-H. 0. Jones Attarney-Buckh0m, Blore, Klarquist and Sparkman ABSTRACT: A pushbutton switch apparatus having cam actuated spring contacts is described in which such contacts also function as resilient supports on which the pushbutton member is mounted and urged into its normal extended posi- PATENTEDFEB 2 3.560.689

44 LIGHT BULB CONTROL CIRCUIT ARTHUR H. MATSON INVENTOR BUC/(HO/W, BLORE, KLA/POU/ST 8 SPAR/(MAN ATTORNEYS BACKGROUND OF INVENTION The present invention relates generally to pushbutton switches having cam actuated switch contacts, and in particular to such switches employing spring contacts directly attached to a printed circuit board and having the pushbutton member mounted on such spring contacts. Thus the spring contacts serve three functions by acting (l) as an electrical switch, (2) as a support for the pushbutton member, and (3) as a spring bias for resiliently urging such member into its normal extended position.

The pushbutton switch of the present invention is especially useful as a momentary type switch on the front panel of a computer terminal for controlling the operation of the electronic computer. Also, by employing a suitable latching mechanism such as that shown in US. Pat. No. 3,271,530 of R. E. Wirsching, the present switch may be operated as a two-position pushbutton switch for a cathode-ray oscilloscope or other electrical apparatus.

The pushbutton switch of the present invention is of a much simpler structure than conventional pushbutton switches, and can be produced'at lower cost while still providing reliable operation over a long, useful lifetime. These advantages are achieved in part by employing the spring contacts of the cam actuated switches as a resilient support for the pushbutton member, so that no additional support member is required to hold the pushbutton member on the switch apparatus and no additional spring is necessary to resiliently urge such member to its normal extended position.

In addition, the switch contacts are directly attached to printed circuit boards so that the switches are connected to the electrical circuits provided on such printed circuit boards without the use of conventional connecting wires. It should be noted that the term printed circuit-board"'as used herein refers to any support plate of electrical insulating material on which conductive areas are provided forming part of an electrical circuit and includes electrical circuit boards fonned by etching processes. As a result of mounting the switch contacts in this manner, such switches are provided with a lower inductance and capacitance which increases their high frequency signal response.

' It is therefore one object of the present invention to provide an improved pushbutton switch of simple and economical construction.

Another object of the invention is to provide an improved pushbutton switch apparatus in which the spring contacts of such switch are also employed as a resilient support for the pushbutton member to hold the member on the switch apparatus and to resiliently urge such member into its normal extended position.

A further object of the invention is to provide an improved pushbutton switch employingcam actuated switch contacts directly attached to a printed circuit board to provide such switch with an improved high frequency signal response.

A still further object of the invention is to provide an illuminated pushbutton switch in which a light bulb is provided within a separate compartment inside the pushbutton member to enable easy access to the bulb by removal of such member for quick replacement of the bulb.

Still another object of the present invention is to provide an improved illuminated pushbutton switch apparatus in which a plurality of light bulbs provided within the pushbutton members are connected by switches actuated by such members to an external control circuit which selectively energizes the light bulbs, such light bulbs, switch contacts, and control circuit being mounted on a single printed circuit board to provide a rugged, compact and inexpensive apparatus.

An additional object of the present invention is to provide an improved pushbutton switch having cam actuated spring contacts on which the pushbutton member is mounted, and in which such member is provided with stops adjacent its upper end to prevent accidental removal of such member and stops at its inner end to prevent the member from damaging the spring contacts.

BRIEF DESCRIPTION OF DRAWINGS Other objects and advantages of the present invention will be apparent from the following detailed description of a preferred embodiment thereof and from the attached drawings of which:

FIG. I is a perspective view of the pushbutton switch apparatus of the present invention and associated control circuitry;

FIG. 2 is an enlarged sectional view taken along the line 2-2 of FIG. 1 showing one pushbutton switch with its contacts in an open position;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2; and

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 3 showing the switch contacts in a closed position.

DESCRIPTION OF PREFERRED EMBODIMENT As shown in FIGS. 1 to 4, a plurality of pushbutton switches 10 of the present invention may be mounted on a printed circuit board I2 which is secured to the front panel 14 of a cathode-ray oscilloscope, computer control terminal, or other electronic instrument by means of mounting bolts 16 and spacer members 18. Each pushbutton switch apparatus includes a pushbutton member 20 of translucent plastic material which is mounted on two pairs of spring contacts 22 provided on opposite sides of such member to resiliently support the pushbutton member on the circuit board 12 for movement between the extended position shown in solid lines and the depressed position shown in dashed lines as shown by arrows 23 in FIG. 2. The spring contacts 22 are directly attached at their fixed ends to the printed circuit board by rivets 24, or by soldering.

Each pair of spring contacts 22 forms an electrical switch which is cam actuated by cam surfaces 26 formed by the edges of two notches 28 provided on the opposite sides of the pushbutton member 20. In the normal, relaxed position of the spring contacts 22 shown in FIG. 2, such contacts resiliently urge the pushbutton member 20 outward into the extended position shown in solid lines. The spring contacts also hold the pushbutton members on the printed circuit board 12 to provide a subassembly which is attached to the mounting panel 14 with the outer ends of the pushbutton members extending through apertures in such panel.

A pair of stop shoulders 30 are provided on the outer ends of two flange portions 32 extending outward from the opposite sides of the pushbutton member. The stop shoulders 30 engage the inner surface of the mounting panel 14 adjacent the aperture through which the pushbutton member extends to prevent such pushbutton member from being accidentally pulled off. This could otherwise happen due to shock if the spring contacts 22 were compressed sufficiently by outward movement of the pushbutton member to enable removal of such member. In addition, a pair of stop projections 34 are provided at the inner ends of the flanges 32 for engagement with the printed circuit board 12 in the depressed position of the pushbutton member 20 shown in FIG. 4. The stop projections 34 act as spacers to prevent the pushbutton member from contacting the conductive areas of the printed circuit and to prevent the cam surfaces 26 from damaging the spring contacts 22 due to overbending.

As shown in FIG. 3, a light bulb 36 containing an incandescent filament 38 is provided within the pushbutton member 20 of each switch apparatus I0 in order to illuminate the pushbutton member. The filament leads of the light bulbs are also electrically attached to the printed circuit board I2 by soldering and connected by conductors 40 to the output of a light bulb control circuit 42. The control circuit 42 may be formed by transistors or a monolithic semiconductor integrated circuit attached to the circuit board 12 so that conductors 40 are part of the printed circuit. One of the two electrical switches actuated by each pushbutton member is employed to energize the light bulb through conductors 44 connected to the input of the control circuit 42 when such pushbutton member is depressed. The control circuit causes the light bulb to remain energized even though the pushbutton member only momentarily closes the switch and is automatically returned to its normal extended position opening such switch when the finger of the operator is removed from the push button. The other contact of the light bulb switch and the other filament lead of the light bulb which are not shown connected to the control circuit 42, may be grounded. The seal end of the light bulb extends through a hole 45 provided in the printed circuit board to accurately position the light bulb between the two switches and to enable such bulb to be supported substantially perpendicular to the printed circuit board. A separate compartment for the light bulb is formed within the pushbutton member by the side flanges 32 and a pair of wall portions 46 to separate the light bulb from the switch contacts 22 so that it does not touch such contacts and affect their switching operation.

As shown in FIG. 2, the cam surfaces 26 formed by the ed ges of the notch 28 include a ramp portion 48 at the open end of the notch which tapers inwardly with distance toward the closed end of the notch from a maximum width of, for example, .320 inch, until such cam surfaces reach an intermediate portion 50 of the notch, where it is of a minimum width of .05 inch. After passing the point of minimum width the cam surfaces 26 proceed outwardly along an arcuate path whose radius of curvature is .056 inch until the cam surface reaches the closed end of the notch. The closed end of the notch 28 is a lateral slot about .258 inch wide provided with arcuate ends having a radius of curvature of .046 inch radius which provides clearance for the free ends 51 of the spring contacts 22. The spring contacts 22 are provided with intermediate contact portions 52 which touch each other in FIG. 4 when the switch is closed and which engage the intermediate cam portion 50in the extended position of the push button shown in FIG. 2. The intermediate contact portions are provided with a similar radius of curvature as the intermediate cam portions 50. The free ends 51 of the switch contacts 22 flare outwardly from their intermediate contact portions 52 into the closed end of the notch 28, while straight leg portions 54 of such contacts, extending between such intermediate contact portions and the fixed ends 56 of the contacts, flare outwardly into the open end of the notch. The angle between such straight leg portions of the pair of contacts 22 is slightly less than the angle formed between the ramp cam surfaces 48 at the open end of the notch which is approximately 90. This clearance between the leg portion 54 of the contact and the ramp portion 48 of the cam surface in the extended position of FIG. 2, enables downward movement of the contact point on the cam surface 26 along the contact leg 54 when the pushbutton is depressed, so that such cam surface urges the spring contacts 22 together and into engagement with one another to close the switch, as shown in FIG. 4.

The spring contacts 22 may be made of any suitable spring metal such as a phosphor bronze alloy and if desired may be coated with gold or any suitable nonoxidizing metal of high electrical conductivity. It should be noted that notch 28 provides the cam surfaces 26 with a shape somewhat similar to the clip end of a clothespin and is clipped over the free ends 51 of the spring contacts to hold the pushbutton member 20 on the circuit board 12. Of course if the pushbutton member 20 were pulled with sufficient force away-from the printed circuit board 12, the spring contacts 22 could be completely removed from the notch 28 to enable removal of such member to provide access to the light bulb 36 for replacement of such bulb when it burns out. The stop shoulder 30 at the outer end of the pushbutton member is provided to prevent accidental removal of such member when the apparatus is mounted on the front panel 14.

It will be obvious to those having ordinary skill in the art that many changes may be made in the above described details of the preferred embodiment of the present invention without departing from the-spirit of the invention. For example, other cam surfaces and different shaped spring contacts can be employed, including the use of only a single movable spring contact for each switch, with the other contact being stationary. Therefore the scope of the present invention should only be determined by the following claims.

I claim: 1. A pushbutton switch apparatus, comprising: a hollow pushbutton member of light transmitting material having two cam surfaces at the opposite sides thereof and a cavity between said cam surfaces;

cam switch means including two separate switches each having a pair of switch contacts with at least one of said contacts being a movable spring contact;

a light bulb positioned within said cavity and mounted between said switches; and

support means mounting said pushbutton member by said cam surfaces on the spring contacts for longitudinal movement between extended and depressed positions so that said spring contacts resiliently urge the pushbutton member into its extended position, and the cam surfaces on said pushbutton member slide along the spring contacts to open and close the switches when the pushbutton member is moved between its extended and depressed positions.

2. A switch apparatus in accordance with claim I in which the light bulb is electrically connected to one of the switches so that said light bulb is energized to illuminate the pushbutton member in response to the closing of said switch by movement of said pushbutton member into its depressed position.

3. A switch apparatus in accordance with claim I in which the spring contacts are fixedly attached at one end to an electrical circuit board.

4. A switch apparatus in accordance with claim 1 in which the outer end of the pushbutton member extends through an aperture in a mounting panel and said pushbutton member is provided with a stop shoulder adjacent its outer end which engages the inner side of said panel adjacent said aperture in the extended position of the pushbutton member which prevents said pushbutton member from coming off the spring contacts.

5. A switch apparatus in accordance with claim 1 in which the inner end of the pushbutton member is provided with a plurality of stop projections which space said pushbutton member a predetermined distance from a support plate to which the spring contacts are attached to prevent damage to the spring contacts due to over-bending in the depressed position of the pushbutton member.

6. A switch apparatus including a plurality of momentary pushbutton switches'in accordance with claim 2 which also includes a control circuit connected between the light bulbs and the switches which energize said light bulbs when said switches are closed, said control circuit maintaining the selected light bulb energized when its corresponding switch reopens until another switch is closed.

7. A switch apparatus in accordance with claim 6 in which the spring contacts, the light bulb leads and the control circuit are all attached to the same electrical circuit board.

8. A pushbutton switch apparatus, comprising:

a pushbutton member having at least one cam surface thereon;

cam switch means including a pair of switch contacts forming a switch with at least one of said contacts being a spring contact, said pushbutton member is provided with a notch in at least one side of its inner end into which the spring contact extends and the cam surface is formed by the edge of the notch; and

support means mounting said pushbutton member on the spring contact for movement between extended and depressed positions so that said spring contact resiliently urges the pushbutton member into its extended position, and the cam surface on said pushbutton member engages the spring contact to open and close the switch when the pushbutton member is moved between its extended and depressed positions.

9. A switch apparatus in accordance with claim 8 in which both contacts of the pair of contacts of the switch are movable spring contacts which are attached to an electrical circuit board and extend into the notch, each of said spring contacts engaging different portions of the cam surface on opposite sides of the notch.

10. A switch apparatus in accordance with claim 9 in which the notch is provided with a narrow intermediate portion between the open end and the closed end of the notch which is of less width than said ends and the spring contacts extend through said intermediate portion with the free ends of said spring contacts flaring outward into the closed end of the notch to hold the pushbutton member on the spring contacts and with the fixed ends of the spring contacts flaring outward into the open end of the notch to resiliently bias the push button in its extended position.

11. A switch apparatus in accordance with claim 10 which includes a second notch on the opposite side of the pushbutton member and a second pair of spring contacts extend into said second notch to form a second switch similar to the first mentioned switch.

12. A switch apparatus in accordance with claim 11 in which a light bulb is mounted within an interior compartment inside the pushbutton member between the two notches and associated pairs of switch contacts, and the filament leads of said light bulb are attached to the circuit board.

Claims

1. A pushbutton switch apparatus, comprising: a hollow pushbutton member of light transmitting material having two cam surfaces at the opposite sides thereof and a cavity between said cam surfaces; cam switch means including two separate switches each having a pair of switch contacts with at least one of said contacts being a movable spring contact; a light bulb positioned within said cavity and mounted between said switches; and support means mounting said pushbutton member by said cam surfaces on the spring contacts for longitudinal movement between extended and depressed positions so that said spring contacts resiliently urge the pushbutton member into its extended position, and the cam surfaces on said pushbutton member slide along the spring contacts to open and close the switches when the pushbutton member is moved between its extended and depressed positions.

2. A switch apparatus in accordance with claim 1 in which the light bulb is electrically connected to one of the switches so that said light bulb is energized to illuminate the pushbutton member in response to the closing of said switch by movement of said pushbutton member into its depressed position.

3. A switch apparatus in accordance with claim 1 in which the spring contacts are fixedly attached at one end to an electrical circuit board.

6. A switch apparatus including a plurality of momentary pushbutton switches in accordance with claim 2 which also includes a control circuit connected between the light bulbs and the switches which energize said light bulbs when said switches are closed, said control circuit maintaining the selected light bulb energized when its corresponding switch reopens until another switch is closed.

8. A pushbutton switch apparatus, comprising: a pushbutton member having at least one cam surface thereon; cam switch means including a pair of switch contacts forming a switch with at least one of said contacts being a spring contact, said pushbutton member is provided with a notch in at least one side of its inner end into which the spring contact extends and the cam surface is formed by the edge of the notch; and support means mounting said pushbutton member on the spring contact for movement between extended and depressed positions so that said spring contact resiliently urges the pushbutton member into its extended position, and the cam surface on said pushbutton member engages the spring contact to open and close the switch when the pushbutton member is moved between its extended and depressed positions.