Long travel elastomer keyboard

• US 4,354,068 A
• Filed: 02/04/1980
• Issued: 10/12/1982
• Est. Priority Date: 02/04/1980
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Sobol, Anthony J. III
• Primary Examiner(s): Scott, James R.
• Application Number:
  US06/118,284
• Time in Patent Office: 981 Days
• Field of Search: 200/5 R, 200/5 A, 200/86 R, 200/1 R, 200/292, 200/340, 200/159 B
• US Class Current: 200/5.00A
• CPC Class Codes: H01H 13/705 characterised by construction, mounting or arrangement of operating parts, e.g. push-buttons or keys

Abstract

A flexible data entry keyboard is disclosed which is formed using a flexible substrate having conducting stripes and switch points thereon. The flexible substrate may be folded back on itself such that the switch points are facing one another in opposed complementary relation. An insulating substrate is positioned between the substrates and has a plurality of apertures in alignment with said switch points. To provide a long travel and high tactile feedback characteristic, an elastometer substrate is positioned over the top of said flexible substrate and has domes thereon which overlay each of said switch points. The domes have actuation surfaces on their underneath side such that when a force is applied to the dome, the dome is compressed and deformed against the switch points and the actuation surface ensures that a reliable and consistent contact is made. When the force is removed, the dome snaps back to its original shape, thereby providing high tactile feedback and assurance to the user that contact has been made.

Claims

1. A keyboard assembly comprising:

a first substrate having first switch points,

a second flexible substrate having conducting stripes and second switch points, said first and second switch points facing one another in opposed complementary relation,

an insulating spacer between said first and second substrates having a plurality of apertures in alignment with said first and second switch points, and

a third substrate positioned over said second substrate and having a dome over the locations of each of said first and second switch points to be deformed to provide travel and tactile feedback when a force is applied to a dome for deforming a portion of the second substrate into a spacer aperture for pressing switch points of the first and second substrates together through the insulating spacer aperture, characterized in that the second substrate is formed of a first selected material for receiving said conductive stripes and switch points thereon and has a first selected thickness permitting repeated flexing deformation of the second substrate to a first selected extent over a long service life, the insulating spacer has a selected limited thickness permitting said second substrate portion to be repeatedly deformed to said first selected extent to press first and second switch points together through said insulating spacer apertures throughout said long service life, and said third substrate is formed of a second, elastomeric material and has each dome thereof proportioned to be deformed to a relatively much greater extent to provide long travel and high tactile feedback when said force is applied to a dome for deforming a portion of the second substrate into a spacer aperture for pressing said switch points of the first and second substrates together through the insulating spacer aperture throughout said long service life.

2. An assembly according to claim 1 further characterized in that said second flexible substrate comprises a material selected from the group consisting of polyester and polyimide films.

3. An assembly according to claim 1 further characterized in that said first and second flexible substrates are formed of a material selected from the group consisting of polyester and polyimide films.

4. An assembly according to claim 1 further characterized in that said spacer has a thickness in the range from 2 to 15 mils, the second substrate has a thickness in the range from 2 to 50 mils, said third substrate is formed of a rubber material having a durometer hardness in the range from 40 to 100 on the Shore A scale, and said dome is a truncated cone adapted to provide travel in the range from 50 to 125 mils upon deformation thereof.

5. An assembly according to claim 3 wherein said first and second flexible substrates are formed from one substrate folded back on itself.

6. An assembly according to claim 4 further characterized in that the thickness of the walls of said dome is in the range of five to ten mils.

7. An assembly according to claim 1 further comprising key means directly in contact with the upper portion of the truncated cone.