PRINTED CIRCUIT KEYBOARD

• US 3,591,749 A
• Filed: 05/12/1969
• Issued: 07/06/1971
• Est. Priority Date: 05/12/1969
• Status: Expired due to Term

• Current Assignee: Comstock James Martin
• Original Assignee: Comstock James Martin
• Inventors: COMSTOCK JAMES MARTIN
• Application Number:
  US04/823,658
• Time in Patent Office: 785 Days
• US Class Current: 200/308
• 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 2201/026 non precious
• CPC Class Codes: H01H 2203/032 Metal foil
• CPC Class Codes: H01H 2205/006 mounted on spacer
• CPC Class Codes: H01H 2207/01 from bottom to top layer
• CPC Class Codes: H01H 2207/012 via underside of substrate
• CPC Class Codes: H01H 2207/022 Plug
• CPC Class Codes: H01H 2209/014 composed of different layers; Lubricant in between
• CPC Class Codes: H01H 2209/016 Protection layer, e.g. for legend, anti-scratch
• CPC Class Codes: H01H 2217/012 Two keys simultaneous considerations
• CPC Class Codes: H01H 2221/05 Force concentrator; Actuating dimple
• CPC Class Codes: H01H 2223/034 Bezel
• CPC Class Codes: H01H 2229/032 Screw
• CPC Class Codes: H01H 2229/034 Positioning of layers
• CPC Class Codes: H04M 1/23 Construction or mounting of dials or of equivalent devices; Means for facilitating the use thereof by improving visibility H04M1/22

Abstract

A printed circuit keyboard having contacts thereon with leads from the contacts passing through the board and connected to conductors on the underside of the board. A ground plane in the form of a conductive sheet is positioned above the contacts and biased out of contact therefrom. This sheet could be Mylar plated with nickel. The Mylar sheet is positioned over an apertured member aligned with the contacts to provide the biasing. The Mylar is sufficiently taut so that only one contact can be positioned against the depressed Mylar sheet at one time. A cellophane or other member can be placed over the Mylar and aligned with the apertures to provide numeric indicators for the keyboard.

Claims

2. The keyboard assembly of claim 1 further including a transparent protective sheet disposed above said indicator sheet.

3. The apparatus of claim 1 wherein said first and second apertures have substantially identical dimensions.

4. THe apparatus of claim 1 wherein said second apertures are dimensioned to receive an actuating member.

5. The apparatus of claim 1 wherein said base member further includes a connector portion, a plurality of conductor paths mounted on the underside of said base member, with individual ones of said conductive paths connected at a first end to individual ones of said contact members, the second end of each of said conductor paths terminating at said connector portion, and a common conductive terminal positioned on the upper side of said base member along said connector portion.

6. A manually actuatable keyboard assembly comprising:

a base member having a plurality of spaced contact members thereon;

a grid member positioned adjacent said base member and having a plurality of apertures, with individual ones of said apertures aligned with individual ones of said contact members;

a plurality of manually actuatable key members positioned adjacent said grid member for reciprocable motion in the direction of said base member, with individual ones of said key members aligned with individual ones of said apertures, each of said key members having a projection extending in said direction and adapted to enter its associated aperture in response to an actuating force;

a plurality of spring members associated with said key members, individual ones of said spring members mounted between said grid member and a selected portion of said associated key member to provide an upward force biasing said associated key member in a nonactuated position;

a cover member positioned adjacent said grid member and having a plurality of apertures aligned with said grid apertures, individual ones of said cover apertures adapted to slidably receive individual ones of said key members; and

at least one resilient conductive strip disposed between said grid member and said cover member and across selected ones of said grid apertures for contacting said aligned contact members in response to the actuation of said aligned key members and corresponding motion of said projections in said direction;

said conductive strip including interlock means preventing contact with more than one of said contact members when more than one of said aligned key members has been actuated.

7. The keyboard assembly of claim 6, wherein said grid apertures are arranged in a plurality of rows, and wherein each of said rows is provided with an associated conductive strip.

8. The apparatus of claim 6 wherein said base member further includes a connector portion, a plurality of conductor paths mounted on the underside of said base member, with individual ones of said conductive paths connected at a first end to individual ones of said contact members, the second end of each of said conductor paths terminating at said connector portion, and a common conductive terminal positioned on the upper side of said base member along said connector portion.