Capacitive switch and panel

• US 4,379,287 A
• Filed: 01/23/1980
• Issued: 04/05/1983
• Est. Priority Date: 08/08/1978
• Status: Expired due to Term

• Current Assignee: Robertshaw Controls Company (Schneider Electric SE)
• Original Assignee: Robertshaw Controls Company (Schneider Electric SE)
• Inventors: Tyler, Hugh J., Conway, William H.
• Primary Examiner(s): Groody, James J.
• Application Number:
  US06/114,596
• Time in Patent Office: 1,168 Days
• Field of Search: 340/365 C, 200/DIG. 1, 200/DIG. 2, 200/5 A, 200/52 R, 200/159 B, 200/275, 307/98, 307/99, 307/116, 361/289, 361/281, 361/339, 361/303, 361/288
• US Class Current: 341/33
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2217/94073 with capacitive detection
• CPC Class Codes: H03K 2217/96023 Details of electro-mechanic connections between different elements, e.g.: sensing plate and integrated circuit containing electronics

Abstract

A user, touch actuable switch panel of the capacitive type that includes one or more touch actuable capacitive switches, each switch including at least two capacitive plate elements formed on a dielectric panel. Conductive paths formed on the dielectric panel interconnect the capacitive plate elements to a source for applying signals to the capacitive plate elements forming said capacitive switches and sensing a resulting change in signal level when a selected switch is actuated by the user. Trim tabs formed on the dielectric panel are provided to balance the effect of stray capacitance between the conductive paths and the capacitive plate elements to maintain the level of change of signal at a determined value upon the actuation of each of said one or more capacitive switches.

Claims

1. In a user, touch actuable switch panel of the capacitive type including one or more touch actuable capacitive switches each switch including at least two capacitive plate means formed on a dielectric panel and conductive paths formed on said dielectric panel for interconnecting the capacitive plate means to means for applying signals to said capacitive plate means forming a respective capacitive switch and sensing a resulting change in signal level when said respective switch is actuated by said user, the improvement comprising:

means formed on said dielectric panel for balancing the effect of stray capacitance between said conductive paths and said capacitive plate means forming said one or more capacitive switches and maintaining the level of said change of signal at a determined value upon the actuation of one of said respective capacitive switches.

2. The invention as defined in claim 1 wherein the capacitive plate means forming said one or more switches and the conductive paths connected thereto are oppositely disposed on opposed sides of said, dielectric panel.

3. The invention as defined in claim 1 wherein said capacitive plate means forming each of said one or more switches are disposed on the same side of said, dielectric panel.

4. The invention as defined in claim 1 wherein said capacitive plate means forming said switch comprises:

an electrically conductive touch plate on one side of said flexible, dielectric tape;

and electrically conductive drive and sense plates disposed on the opposing side of said, dielectric panel opposite said touch plate, said conductive paths interconnecting said sense and drive plates to said electrical circuit means whereby said capacitive switch is conductively coupled to ground when actuated.

5. The invention as defined in claim 4 wherein said dielectric panel is formed of at least two flexible films of dielectric material affixed together, one of said sense or drive pads being disposed on the outer side of a first of said flexible, dielectric films and the other of said sense or drive plates being disposed between and upon the inside of either of said two films of dielectric material, said touch plate being disposed on the outside of said second film of flexible dielectric material.

6. The invention as defined in claim 5 including a coating of non-conductive material around said touch plate on said outside of said second flexible film.

7. The invention as defined in claim 2 wherein said dielectric panel is a flexible, dielectric tape.

8. The invention as defined in claim 3 wherein said dielectric panel is a flexible, dielectric tape.