DOME SHEET WITH LIGHT GUIDE FOR MEMBRANE SWITCH

• US 20080197002A1
• Filed: 01/22/2008
• Published: 08/21/2008
• Est. Priority Date: 01/22/2007
• Status: Active Grant

• Current Assignee: MMI Costa Mesa, LLC
• Original Assignee: Coactive Technologies Pte Limited
• Inventors: Jeffery, Peter Andrew, Lin, Jason Tsi-Tsun
• Granted Patent: US 7,888,613 B2
• Time in Patent Office: Days
• US Class Current: 200/310
• CPC Class Codes: H01H 13/83 characterised by legends, e.g. Braille, liquid crystal displays, light emitting or optical elements
• CPC Class Codes: H01H 2205/026 Adhesive sheet
• CPC Class Codes: H01H 2219/044 Edge lighting of layer
• CPC Class Codes: H01H 2219/056 Diffuser; Uneven surface
• CPC Class Codes: H01H 2219/062 Light conductor

Abstract

In an embodiment, a membrane switch may include a flexible light guide having a first refractive index. The flexible light guide may include a first wall, an opposing second wall, and one or more additional walls. One or more of the first wall, the second wall and the additional walls may be disposed adjacent to a substance including a second refractive index that is lower than the first refractive index.

Claims

1. A membrane switch, comprising:

a flexible light guide having a first refractive index, the flexible light guide comprising;

a first wall,

an opposing second wall, and

one or more additional walls,

wherein one or more of the first wall, the second wall and the additional walls are disposed adjacent to a substance comprising a second refractive index that is lower than the first refractive index.

2. The membrane switch of claim 1 wherein:

the substance having the second refractive index is disposed adjacent to the first wall, and

the first wall comprises an uneven surface which manages light reflected from the second wall.

3. The membrane switch of claim 2 wherein the uneven surface comprises at least one of:

a plurality of bumps, dimples, scratches, hash marks, textures, depressions, or holes.

4. The membrane switch of claim 1 wherein:

the substance having the second refractive index is disposed adjacent to the first wall, and

the first wall comprises a patterned surface which manages light reflected from the second wall.

5. The membrane switch of claim 1 wherein the first wall comprises one or more moveable contacts.

6. The membrane switch of claim 1, further comprising:

one or more moveable contacts attached directly to the first wall via an adhesive layer.

7. The membrane switch of claim 1, further comprising:

one or more moveable contacts attached to the substance having the second refractive index.

8. The membrane switch of claim 1, further comprising:

a movable contact disposed such that movement of the first wall will move the movable contact; and

a circuit board comprising a plurality of fixed electrical contacts, wherein the moveable contact is positioned over a first one of the fixed electrical contacts so that the moveable contact touches the first fixed electrical contact when depressed and does not touch the first fixed electrical contact when relaxed.

9. The membrane switch of claim 2 wherein a substance having the second refractive index is also disposed adjacent to the second wall.

10. The membrane switch of claim 1, further comprising:

a reflective material disposed adjacent to the substance having the second refractive index.

11. The membrane switch of claim 10 wherein the reflective material is specular.

12. A dome sheet, comprising:

a light guide;

a plurality of moveable contacts; and

a patterned adhesive which the bonds the light guide to the moveable contacts so that the patterned adhesive forms one or more gaps between the moveable contacts and the light guide.

13. The dome sheet of claim 12 wherein:

the light guide comprises a first wall and an opposing second wall, and

the first wall is bonded to the patterned adhesive.

14. The dome sheet of claim 13 wherein the first wall comprises an uneven surface and the uneven surface of the first wall comprises at least one of:

a plurality of bumps, dimples, scratches, hash marks, applied patterns, textures, depressions, or holes.

15. The dome sheet of claim 13 wherein the first wall comprises a patterned surface.

16. The dome sheet of claim 12 wherein the one or more gaps in the patterned adhesive form a channel between a plurality of moveable contacts.

17. The dome sheet of claim 13 wherein the second wall comprises a flexible, reflective material.

18. The dome sheet of claim 12 wherein the patterned adhesive comprises

a plurality of adhesive regions having a reflective property and position so that at least some light, when reflected from any of the regions, is reflected at an angle less than a critical angle of the light guide, and

the regions are positioned so that the one or more gaps cause total internal reflection inside the light guide.

19. The dome sheet of claim 12, further comprising:

a spacer positioned to attach to the light guide in areas where no movable contacts are in contact with the light guide.

20. The dome sheet of claim 12 wherein the patterned adhesive comprises a light reflecting adhesive.

21. The dome sheet of claim 12 wherein the one or more gaps are sealed inside the dome sheet.

22. A membrane switch, comprising:

a circuit hoard comprising a plurality of fixed electrical contacts;

a moveable contact positioned over a first one of the fixed electrical contacts so that the moveable contact touches the first fixed electrical contact when depressed and does not touch the first fixed electrical contact when relaxed;

a patterned adhesive bonded to the moveable contact; and

a light guide bonded to the patterned adhesive,

wherein the patterned adhesive bonds the light guide to the moveable contact so that the patterned adhesive forms one or more gaps between the moveable contact and the light guide.