BACKLIGHTING INDUCTIVE TOUCH BUTTONS

• US 20110050626A1
• Filed: 05/26/2010
• Published: 03/03/2011
• Est. Priority Date: 09/01/2009
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Microchip Technology Incorporated
• Inventors: Curtis, Keith, Porter, Stephen B.
• Granted Patent: US 8,408,723 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: H03K 17/952 using inductive coils
• CPC Class Codes: H03K 17/96 Touch switches specially adapted for electronic time-pieces with no moving parts G04G21/08
• CPC Class Codes: H03K 2217/96038 Inductive touch switches
• CPC Class Codes: H03K 2217/96042 with illumination
• CPC Class Codes: H03K 2217/96046 Key-pad combined with display, back-lit
• CPC Class Codes: H03K 2217/9655 using a single or more light guides

Abstract

Backing lighting of induction touch keys is accomplished with a spacer layer surrounding an inductive touch sensor coil and a light source on a substrate, and light transmissive layer having a suspended metal disk proximate to the inductive touch sensor coil. A protective fascia may be placed over the light transmissive layer and spacer layer. When the light transmissive layer is displaced toward the inductive touch sensor coil the impedance value of the inductive touch sensor coil changes and the change is detected. Materials used that are translucent (light transmissive) may be continuous and solid, and opaque materials may have openings therein for transmission of light therethrough.

Claims

1. A backlit inductive touch sensor key, comprising:

a substrate;

an inductive sense coil on the substrate;

a light source;

a spacer layer on the substrate and having an opening that surrounds the inductive sense coil and the light source; and

a over-layer having opening therein to allow light to pass therethrough from the light source, the over-layer is attached to the spacer layer and forms a light transmission cavity between the substrate and the over-layer; and

an over-mold button attached to a side of the over-layer opposite to the light transmission cavity, the over-mold button being light transmissive;

wherein when the over-mold button is biased toward the inductive sense coil, an impedance value of the inductive sense coil changes.

2. The backlit inductive touch sensor key according to claim 1, further comprising a metal target attached on a face of the over-layer proximate to the inductive sense coil, wherein when the metal target is biased toward the inductive sense coil, the impedance value of the inductive sense coil changes.

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

4. The backlit inductive touch sensor key according to claim 3, wherein the at least one LED is on a same side of the substrate as the inductive sense coil and illuminates the light transmission cavity.

5. The backlit inductive touch sensor key according to claim 3, wherein the at least one LED is on an opposite side of the substrate as the inductive sense coil and illuminates the light transmission cavity.

6. The backlit inductive touch sensor key according to claim 3, wherein the at least one LED is in the substrate and illuminates the light transmission cavity.

7. The backlit inductive touch sensor key according to claim 1, wherein the over-layer is metal.

8. The backlit inductive touch sensor key according to claim 7, wherein the metal over-layer is selected from the group consisting of aluminum, steel, stainless steel, copper, and titanium.

9. The backlit inductive touch sensor key according to claim 1, wherein the over-layer is nonmetallic.

10. The backlit inductive touch sensor key according to claim 9, wherein the nonmetallic over-layer is selected from the group consisting of plastic, Teflon, and polyamide.

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

12. A backlit inductive touch sensor key, comprising:

a substrate;

an inductive sense coil on the substrate;

a light source;

a spacer layer on the substrate and having an opening that surrounds the inductive sense coil and the light source; and

a flexible layer of light transmissive material, the flexible layer is over the inductive sense coil and light source, and is attached to the spacer layer wherein a light transmission cavity is formed between the substrate and the flexible layer;

wherein when the flexible layer is biased toward the inductive sense coil, an impedance value of the inductive sense coil changes.

13. The backlit inductive touch sensor key according to claim 12, further comprising a metal target attached on a face of the flexible layer proximate to the inductive sense coil, wherein when the metal target is biased toward the inductive sense coil, the impedance value of the inductive sense coil changes.

14. The backlit inductive touch sensor key according to claim 12, wherein the light source is at least one light emitting diode (LED).

15. The backlit inductive touch sensor key according to claim 14, wherein the at least one LED is on a same side of the substrate as the inductive sense coil and illuminates the light transmission cavity.

16. The backlit inductive touch sensor key according to claim 14, wherein the at least one LED is on an opposite side of the substrate as the inductive sense coil and illuminates the light transmission cavity.

17. The backlit inductive touch sensor key according to claim 14, wherein the at least one LED is in the substrate and illuminates the light transmission cavity.

18. The backlit inductive touch sensor key according to claim 12, further comprising an over-layer on the flexible layer.

19. The backlit inductive touch sensor key according to claim 18, wherein the over-layer is made of light transmissive material.

20. The backlit inductive touch sensor key according to claim 18, wherein the over-layer is made of light opaque material and has opening therein for light from the light source to pass therethrough.

21. The backlit inductive touch sensor key according to claim 18, wherein the over-layer is metal.

22. The backlit inductive touch sensor key according to claim 21, wherein the metal over-layer is selected from the group consisting of aluminum, steel, stainless steel, copper, and titanium.

23. The backlit inductive touch sensor key according to claim 18, wherein the over-layer is nonmetallic.

24. The backlit inductive touch sensor key according to claim 23, wherein the nonmetallic over-layer is selected from the group consisting of plastic, Teflon, and polyamide.

25. The backlit inductive touch sensor key according to claim 12, wherein the flexible layer has opening therein for flexure and for light from the light source to pass therethrough.

26. The backlit inductive touch sensor key according to claim 12, wherein the substrate is a printed circuit board.

27. A backlit inductive touch sensor key, comprising:

a substrate;

an inductive sense coil on the substrate;

a light source;

a spacer layer on the substrate and having an opening that surrounds the inductive sense coil and the light source;

a flexible fascia layer adapted to allow light therethrough, the flexible fascia layer is over the inductive sense coil and light source, and is attached to the spacer layer wherein a light transmission cavity is formed between the substrate and the flexible fascia layer;

a light translucent layer attached to a side of a portion of the flexible fascia layer facing and inside of the light transmission cavity; and

a metal target attached to a face of the light translucent layer proximate to the inductive sense coil;

wherein when the flexible fascia layer is biased toward the inductive sense coil, an impedance value of the inductive sense coil changes.

28. The backlit inductive touch sensor key according to claim 27, wherein the light source is at least one light emitting diode (LED).

29. The backlit inductive touch sensor key according to claim 28, wherein the at least one LED is on a same side of the substrate as the inductive sense coil and illuminates the light transmission cavity.

30. The backlit inductive touch sensor key according to claim 28, wherein the at least one LED is on an opposite side of the substrate as the inductive sense coil and illuminates the light transmission cavity.

31. The backlit inductive touch sensor key according to claim 28, wherein the at least one LED is in the substrate and illuminates the light transmission cavity.

32. The backlit inductive touch sensor key according to claim 27, wherein the flexible fascia layer is made of light transmissive material.

33. The backlit inductive touch sensor key according to claim 27, wherein the flexible fascia layer is made of light opaque material and has opening therein for light from the light source to pass therethrough.

34. The backlit inductive touch sensor key according to claim 27, wherein the flexible fascia layer is metal.

35. The backlit inductive touch sensor key according to claim 34, wherein the flexible metal fascia layer is selected from the group consisting of aluminum, steel, stainless steel, copper, and titanium.

36. The backlit inductive touch sensor key according to claim 27, wherein the flexible fascia layer is nonmetallic.

37. The backlit inductive touch sensor key according to claim 36, wherein the flexible nonmetallic fascia layer is selected from the group consisting of plastic, Teflon, and polyamide.

38. The backlit inductive touch sensor key according to claim 27, wherein the substrate is a printed circuit board.