Physical force capacitive touch sensors having conductive plane and backlighting

• US 8,858,003 B2
• Filed: 05/10/2012
• Issued: 10/14/2014
• Est. Priority Date: 10/27/2008
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Microchip Technology Incorporated
• Inventors: Porter, Stephen B., Curtis, Keith, Duvenhage, Fanie
• Primary Examiner(s): BRUCE, DAVID VERNON
• Application Number:
  US13/468,504
• Publication Number:
  US 20120217147A1
• Time in Patent Office: 887 Days
• Field of Search: 362/23.03, 362/23.05
• US Class Current: 362/23.03
• CPC Class Codes: G06F 3/0202 Constructional details or processes of manufacture of the input device
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2217/960755 Constructional details of capacitive touch and proximity switches
• CPC Class Codes: H03K 2217/960785 with illumination
• CPC Class Codes: H03K 2217/960795 using organic light emitting devices, e.g. light emitting polymer [OEP] or OLED
• CPC Class Codes: H03K 2217/9655 using a single or more light guides

Abstract

A physical force capacitive touch sensor comprises a capacitive sensor element on a substrate, a physically deformable electrically insulating spacer over the capacitive sensor element and a conductive plane over the physically deformable electrically insulating spacer. A protective fascia may be placed over the conductive plane provides an environmental seal for physical and weather protection, but is not essential to operation of the capacitive touch sensor. Back lighting is accomplished with a light transmissive layer having a suspended metal target proximate to the capacitive touch sensor plate. When the light transmissive layer and metal target are displaced toward the capacitive touch sensor plate the capacitance value of the capacitive touch sensor plate changes and that change is detected.

Claims

1. A backlit capacitive touch sensor key, comprising:

a substrate;

a capacitive sensor plate on the substrate;

a light source;

a spacer layer on the substrate, wherein the spacer layer has an opening that surrounds the capacitive sensor plate and the light source;

a flexible light translucent layer;

a metal target attached to a face of the flexible light translucent layer proximate to the capacitive sensor plate, wherein the metal target has opening therein to allow light to pass therethrough;

the flexible light translucent layer is attached to the spacer layer over the capacitive sensor plate and light source, wherein a light transmission cavity is formed between the substrate and the flexible light translucent layer and metal target;

whereby when the flexible light translucent layer and metal target are biased toward the capacitive sensor plate, a capacitance value of the capacitive sensor plate changes.

2. The backlit capacitive touch sensor key according to claim 1, wherein the light source is at least one light emitting diode (LED).

3. The backlit capacitive touch sensor key according to claim 1, wherein the light source is an organic light emitting diode (OLED) layer.

4. The backlit capacitive touch sensor key according to claim 1, wherein the light source is an electroluminescence (EL) layer.

5. The backlit capacitive touch sensor key according to claim 1, wherein the metal target is light opaque and has at least one opening therein for light from the light source to pass therethrough.

6. The backlit capacitive touch sensor key according to claim 1, further comprising a flexible over-layer over the flexible light translucent layer.

7. The backlit capacitive touch sensor key according to claim 6, wherein the flexible over-layer is made of light transmissive material.

8. The backlit capacitive touch sensor key according to claim 6, wherein the flexible over-layer is made of light opaque material and has opening therein for light from the light source to pass therethrough.

9. The backlit capacitive touch sensor key according to claim 8, wherein the flexible over-layer is metal.

10. The backlit capacitive touch sensor key according to claim 8, wherein the flexible over-layer is nonmetallic.

11. The backlit capacitive touch sensor key according to claim 1, wherein the substrate is a printed circuit board.