Keyboard pushbutton switch assembly having multilayer contact and circuit structure

• US 3,917,917 A
• Filed: 08/22/1974
• Issued: 11/04/1975
• Est. Priority Date: 08/23/1973
• Status: Expired due to Term

• Current Assignee: Taneo Murata
• Original Assignee: Taneo Murata
• Inventors: Murata, Taneo
• Primary Examiner(s): Scott, James R.
• Application Number:
  US05/499,600
• Time in Patent Office: 439 Days
• Field of Search: 200/1R,5R,5A,83N,86R,275,159B,275,294-296,302,303,307,340 197/98 340/365R,365A,365S,365C,365E
• US Class Current: 200/517
• CPC Class Codes: H01H 13/702 with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
• CPC Class Codes: H01H 13/785 characterised by the material of the contacts, e.g. conductive polymers
• CPC Class Codes: H01H 13/807 characterised by the spatial arrangement of the contact sites, e.g. superimposed sites
• CPC Class Codes: H01H 2201/026 non precious
• CPC Class Codes: H01H 2203/02 Interspersed fingers
• CPC Class Codes: H01H 2215/034 Separate snap action
• CPC Class Codes: H01H 2223/03 Separate key housing
• CPC Class Codes: H01H 2223/034 Bezel
• CPC Class Codes: H01H 2225/002 superimposed
• CPC Class Codes: H01H 2229/032 Screw
• CPC Class Codes: H01H 2229/034 Positioning of layers
• CPC Class Codes: H01H 2233/014 Snap coupling
• CPC Class Codes: H01H 2233/056 with limited freedom

Abstract

A push-button switch having a plurality of depressable push buttons includes a resilient metal plate provided beneath each push button which is bent in a snapping manner thereby depressing a movable contact provided on a first printed circuit sheet toward a contact assembly provided on a second printed circuit sheet. Upon closure of the movable contact and the contact assembly, another movable contact provided on the rear side of the second printed circuit sheet is depressed toward another contact assembly provided on a printed circuit base board thereby closing the contact assembly.

Claims

1. A snap-acting, multicontact, multicircuit, pushbutton switch comprising:

a printed circuit base board provided with a plurality of fixed contact assemblies each connected to one pair of a first set of terminals;

a first printed circuit sheet made of an insulating flexible film, a plurality of movable contacts fixed on the rear side of said first printed circuit sheet;

a second printed circuit sheet interposed between said printed circuit base board and said first printed circuit sheet and made of an insulating flexible film, a plurality of movable contact assemblies fixed on The front side of said second printed circuit sheet each contact assembly connected to one pair of a second set of terminals, and a plurality of movable contacts at positions aligning with the contact assemblies on the front side thereof and fixed on the rear side of said second printed circuit sheet;

two insulating flexible film sheets, each having a plurality of holes at positions aligning with said contacts and being interposted between said first and second printed circuits sheets and between the second printed circuit sheet and the printed circuit base board respectively;

a plurality of push buttons arranged on the front side of the first printed circuit sheet in alignment with said plurality of movable contacts and contact assemblies, and a plurality of snap-action resilient spring plates, with one resilient plate provided directly beneath each push button and without another metal spring for each push button, whereby when any one of the push buttons is depressed it pushes its corresponding resilient plate, pushing the resilient plate downward until it snaps into a reverse position thereby contacting the first printed circuit sheet and forcing the movable contacts of the first printed circuit sheet downward until they meet in physical contact with the movable contact assemblies of the second printed circuit sheet and forcing the movable contacts of the second printed circuit sheet downward until they meet in physical contact with the contact assemblies of the printed circuit base board, and when the push button is released the push button is brought back to its original position by the action of the resilient plate while the movable contacts are separated from the contact assemblies due to the flexibility of the printed circuit sheets.

2. A push-button switch as set forth in claim 1 wherein said plurality of push buttons are received in a plurality of casings, respectively, and each of the casings is provided with a pair of legs each having a detent at the lower end thereof.

3. A push-button switch as set forth in claim 2 wherein said first and second printed circuit sheets, said printed circuit base board, and said two insulating sheets having holes, are all provided with a plurality of pairs of holes in vertically aligned positions so that when said pairs of legs of said casings are passed through said pairs of holes, said first and second printed circuit sheets, printed circuit base board, and two insulating sheets are superimposed in precisely aligned manner.

4. A push-button switch as set forth in claim 2 wherein each of said casings is further provided with four pillar-like projections downwardly extending from the four corners of the casing.

5. A push-button switch as set forth in claim 4 wherein said first and second printed circuit sheets, said printed circuit base board, and two insulating sheets are all further provided with a plurality of sets each including four holes therethrough in vertically aligned positions so that when said four pillar-like projections of the casing pass through said four in one set of holes, said first and second printed circuit sheets, said printed circuit base board, and two insulating sheets are superimposed in far more precisely aligned manner.

6. A push-button switch as set forth in claim 1 wherein said resilient plate is made of a thin metal sheet having three limbs, the central limb of which is longer than the two side limbs, whereby when the central limb is depressed by a push button, the bending state of the resilient plate is changed in a snapping manner into the reversely bent state.

7. A push-button switch as set forth in claim 1 wherein an upper frame having a plurality of holes is further provided so that said plurality of push buttons are upwardly exposed through said plurality of holes.

8. A push-button switch as set forth in claim 7 wherein a substantially rectangular recessed portion is formed around each of said plurality of holes on the rear side of said upper frame, and said pLurality of casings are tightly received in said recessed portions.

9. A push-button switch as set forth in claim 7 wherein said upper frame is further provided with two side ribs along the lower side edges, and all of the first and second printed circuit sheets, said printed circuit base board, and two insulating sheets superimposed are received between said side ribs of the upper frame when the push-button switch is assembled.

10. A push-button switch as set forth in claim 9 wherein a plurality of mounting screws are further driven from the rear side of the printed circuit base board to a plurality of threaded holes in the upper frame penetrating through the first and second printed circuit sheets and two insulating sheets.

11. A push-button switch as in claim 6 wherein said resilient plate is further provided with four holes at the four corners thereof.

12. A push-button switch as in claim 8 wherein each of said casings has a stepped portion which fits into said recessed portion in a tight manner.

13. A push-button switch as set forth in claim 2 wherein each of said plurality of push-buttons is further provided an integral pair of projections of a substantially triangular detent cross-section projecting from both sides of the lower part of the push-button, and each of said casings has a downwardly extending rib which fits with and retains said projections.

14. A push-button switch as set forth in claim 1 wherein said plurality of push-buttons are further provided with a downwardly projecting portion at the center of the lower surface.

15. A contact assembly as set forth in claim 1 wherein said plurality of contact members are further provided with leads which connect said contact assemblies to terminals located on the longitudinal ends of said second printed circuit sheet and printed circuit base board.

16. A snap-acting, pushbutton switch comprising:

a printed circuit base board provided with at least one fixed contact assembly;

a printed circuit sheet made of an insulating flexible film placed over the printed circuit base board and provided with at least one movable contact aligning with said fixed contact assembly;

a flexible insulating sheet having at least one hole aligning with said contact and contact assembly and being interposed between the printed circuit sheet and the printed circuit base board;

a push button arranged on the front side of the printed circuit sheet in alignment with the contact and contact assembly, a resilient plate provided beneath the push button;

whereby when the push button is depressed its corresponding resilient plate is pushed downward until it snaps into a reverse position thereby forcing the contact of the printed circuit sheet downward until it comes into physical contact with the contact assembly of the printed circuit base board and when the push button is released the push button is brought back to its original position by the action of the resilient plate while the movable contact is separated from the contact assembly due to the flexibility of the printed circuit sheets.