CALCULATOR KEYBOARD SWITCH WITH DISC SPRING CONTACT AND PRINTED CIRCUIT BOARD

• US 3,796,843 A
• Filed: 01/02/1973
• Issued: 03/12/1974
• Est. Priority Date: 01/02/1973
• Status: Expired due to Term

• Current Assignee: Alan C. Yoder, Gilbert H. Durkee, Per G. Wareberg
• Original Assignee: Alan C. Yoder, Gilbert H. Durkee, Per G. Wareberg
• Inventors: Durkee, Gilbert H., Wareberg, Per G., Yoder, Alan C.
• Primary Examiner(s): Scott, James R.
• Application Number:
  US05/320,147
• Time in Patent Office: 434 Days
• Field of Search: 200/1R,5R,5A,52R,DIG.1,159R,159B,166BH 340/365A
• US Class Current: 200/5.00A
• CPC Class Codes: H01H 13/7006 comprising a separate movable contact element for each switch site, all other elements being integrated in layers
• CPC Class Codes: H01H 13/785 characterised by the material of the contacts, e.g. conductive polymers
• CPC Class Codes: H01H 2201/026 non precious
• CPC Class Codes: H01H 2203/04 to facilitate connections
• CPC Class Codes: H01H 2203/042 to avoid cross-overs
• CPC Class Codes: H01H 2205/024 Means to facilitate positioning
• CPC Class Codes: H01H 2209/032 non elastomeric
• CPC Class Codes: H01H 2227/026 Separate dome contact
• CPC Class Codes: H01H 2229/014 Electro deposition
• CPC Class Codes: H01H 2229/016 Selective etching
• CPC Class Codes: H01H 2229/026 Riveting
• CPC Class Codes: H01H 2231/002 Calculator, computer

Abstract

A keyboard switch assembly including a printed circuit board having four switch terminals on one side of the board, three of the terminals being arranged in a triangle and the fourth disposed within the triangle. Conductors on the one side of the board are respectively joined to the interior terminal and at least one of the three terminals. A conductive, generally triangular, snap-acting dome switch member is provided having arcuate apices, projections being respectively formed from the apices and respectively engaging the three terminals thereby spacing the periphery of the switch element from the one surface of the printed circuit board and the conductors thereon, at least the conductor connected to the interior terminal extending under the dome. The switch element has a fourth protection formed from the interior of the dome adjacent the center thereof which is in registry with the interior terminal and engages that terminal when the dome is deflected thereby completing an electrical circuit between the three terminals and the interior terminal. A layer of insulating material covers the conductors exclusive of the terminals. A sheet of insulating material covers the insulating layer and has an opening therein which receives and locates the switch member. Another sheet of insulating material covers the first sheet and the switch member. A plate covers the second insulating sheet and has an opening therein which receives a push button in registry with the switch element, depression of the push button actuating the dome of the switch member to a nonovercenter, deflected position in which the interior projection on the dome engages the interior switch terminal.

Claims

1. In a keyboard switch assembly including a push button manually actuable from an inactive to a switch-actuating position, and a conductive switch member including a resilient element actuated by said push button from a normal to a deflected position and resiliently returning to its normal position upon removal of force from said bush button, the improvement comprising an insulative board having opposite surfaces, one only of said surfaces having first and second elongated conductors thereon, said first conductor including a first switch terminal portion and said second conductor including a second switch terminal portion, said conductors and terminal portions being generally coplanar, said switch element being positioned in facing relationship with said one surface and said conductors, said switch element having first and second spaced contact areas thereon, said first contact area engaging said first terminal portion, said second contact area being in registry with said second terminal portion and engaging the same when said element is in said deflected position thereby electrically connecting said first and second terminal portions, and mean for holding said push button, switch member and board in operative relationship.

2. The assembly of claim 1 further comprising a layer of insulating material covering said conductors excluding said terminal portions.

3. The assembly of claim 2 wherein said element is a snap-acting dome, said second contact area being at the center of said dome, said one surface of said board having a third conductor thereon at least partially surrounding said second terminal portion, closely spaced therefrom and generally coplanar therewith, the area of said dome surrounding said second contact area engaging the insulation covering said third conductor upon further deflection of said dome following engagement of said second contact area with said second terminal portion thereby to protect said second contact area.

4. The assembly of claim 1 wherein said one surface of said board has at least a third conductor thereon intermediate and spaced from said first and second conductors and generally coplanar therewith, said third conductor extending under said element from a location on said one surface remote therefrom, said element in its deflected position being spaced from said third conductor, there being no electrical connection between said third conductor and said element in either position thereof.

5. The assembly of claim 4 wherein said element is a snap-acting dome, said second contact area being at the center of said dome, said third conductor being intermediate said first and second terminal portions and generally coplanar therewith.

6. The assembly of claim 1 wherein said one surface of said board has a third conductor thereon at least partially surrounding said second terminal portion, spaced therefrom and generally coplanar therewith, the area of said element surrounding saId second contact area engaging said third conductor upon further deflection of said element following engagement of said second contact with said second terminal portion thereby to protect said element and second contact area.

7. The assembly of claim 1 wherein a section of at least said second conductor extends under said element from a location on said one surface remote therefrom.

8. The assembly of claim 1 wherein said element is a snap-acting dome, said second contact area being at the center of said dome.

9. The assembly of claim 8 wherein said second contact area comprises a projection on the interior of said dome.

10. The assembly of claim 8 further comprising third, fourth and fifth switch terminals on said one surface of said board, said third through fifth terminals and said first terminal portion being arranged in a rectangle with said second terminal portion in the interior therof, said first contact area comprising a first projection formed from said dome adjacent the periphery thereof, said dome having second, third and fourth projections formed therefrom adjacent the periphery thereof and respectively engaging said third, fourth and fifth switch terminals, said projections spacing the periphery of said dome from said one surface of said board and said conductor, said second contact area comprising a fifth projection formed from the interior of said dome.

11. The assembly of claim 10 wherein said switch element is generally rectangular with arcuate corners coaxial with the center of said dome, said first through fourth projections being formed from said corners.

12. The assembly of claim 8 wherein said first contact area comprises a projection on said switch element spacing the periphery of said dome from said one surface of said board and said conductors.

13. The assembly of claim 12 wherein said projection is formed from said dome adjacent the periphery thereof.

14. The assembly of claim 13 wherein said switch member includes a flat portion joined to the periphery of said dome, said projection being formed from said flat portion.

15. The assembly of claim 8 further comprising third and fourth switch terminals on said one surface of said board, said third and fourth terminals and said first terminal portion being arranged in a triangle with said second terminal portion in the interior thereof, said first contact area comprising a first projection formed from said dome adjacent the periphery thereof, said dome having second and third projections formed therefrom adjacent the periphery thereof and respectively engaging said third and fourth switch terminals, said projections spacing the periphery of said dome from said one surface of said board and said conductors, said second contact area comprising a fourth projection formed from the interior of said dome.

16. The assembly of claim 15 wherein said switch element generally triangular with arcuate apices coaxial with the center of said dome, said first, second and third projections being formed from said apices.

17. The assembly of claim 16 wherein said holding means comprises a layer of insulating material covering said conductors excluding said terminal portions and terminals, a first sheet of insulating material covering said layer and having an opening therein receiving said switch element and conforming thereto for locating the same, a second sheet of insulating material covering said first sheet and switch element, and a plate member covering said second sheet and having an opening therein receiving said push button, said push button acting on said dome through said second sheet.

18. The assembly of claim 16 wherein a section of at least said second conductor extends under said dome from a location on said one surface remote therefrom, said one surface of said board having a third conductor thereon at least partially surrounding said second terminal portion, spaced thereon and generally coplanar therewith, said conductors exclusive of said terminal portions haviNg a layer of insulating material thereon, the area of said dome surrounding said fourth projection engaging the insulation covering said third conductor upon further deflection of said dome following engagement of said second contact area with said second terminal portion thereby to protect said fourth projection.

19. The assembly of claim 18 wherein said third conductor completely surrounds said second terminal portion and is joined to said second conductor.

20. The assembly of claim 18 wherein said third conductor partially surrounds said second terminal portion and is joined to a fourth conductor on said one surface of said board which extends under said dome.

21. The assembly of claim 18 wherein said first conductor is joined to at least said second terminal.

22. The assembly of claim 18 wherein said board has a fourth conductor thereon which extends under said dome.