Capacitive touch switch and domestic appliance provided with such switch

• US 7,923,654 B2
• Filed: 10/08/2008
• Issued: 04/12/2011
• Est. Priority Date: 10/08/2007
• Status: Expired due to Fees

• Current Assignee: Whirlpool Corporation
• Original Assignee: Whirlpool Corporation
• Inventors: Goransson, Bjorn, Zeijlon, Anders, Lazzarotto, Roberto, Arena, Giuseppe, Arione, Ettore
• Primary Examiner(s): Figueroa; Felix O
• Application Number:
  US12/247,289
• Publication Number:
  US 20090090611A1
• Time in Patent Office: 916 Days
• Field of Search: 200/600, 200310-314, 345/168, 345/173, 345/174, 341/33, 400/479.1
• US Class Current: 200/600
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2217/96079 using a single or more light guides

Abstract

A capacitive touch switch having a printed circuit board and capacitive electrode provided on a surface of the printed circuit board is disclosed. The printed circuit board is interposed between a transparent planar light guide and the electrode, the planar light guide being attached to a first face of a transparent cover whose second face is adapted to be touched by the user, a light source being connected to the printed circuit board and being able to convey light to the planar light guide.

Claims

1. A capacitive touch switch comprising:

a non-conductive transparent cover including a touch-sensitive area adapted to be touched by a user;

a planar light guide extending beneath the touch-sensitive area of the non-conductive transparent cover, the planar light guide including an end portion;

a capacitive electrode provided on a surface of a printed circuit board, the printed circuit board interposed between the planar light guide and the capacitive electrode; and

a light source connected to the printed circuit board adjacent the end portion of the planar light guide, wherein light generated by the light source is directed into the end portion of the planar light guide and through the planar light guide beneath the touch-sensitive area of the non-conductive transparent cover.

2. The capacitive touch switch according to claim 1, further comprising:

a non-conductive layer interposed between the planar light guide and the non-conductive transparent cover.

3. The capacitive touch switch according to claim 2, wherein the non-conductive layer is constituted by transparent paint.

4. The capacitive touch switch according to claim 1, wherein the light source is mounted to a face of the printed circuit board opposite the planar light guide and adjacent an L-shaped edge of the planar light guide, wherein the light generated by the light source enters the planar light guide via the L-shaped edge portion before being directed through the planar light guide beneath the touch-sensitive area of the non-conductive transparent cover.

5. The capacitive touch switch according to claim 1, wherein the light source is a reverse mounted light emitting diode installed on a side of the printed circuit board opposite the planar light guide, the printed circuit board being provided with an opening for conveying the light generated by the light source to the end portion of the planar light guide.

6. The capacitive touch switch according to claim 1, further comprising:

an icon serigraphy on the non-conductive transparent cover.

7. The capacitive touch switch according to claim 1, wherein the light source is provided on a surface of the printed circuit board facing the planar light guide such that the light source is in contact with the end portion of the planar light guide.

8. The capacitive touch switch according to claim 1, wherein the capacitive touch switch is adapted to be electrically bridged to one or more adjacent touch switches in order to change the overall configuration of a control panel.

9. The capacitive touch switch according to claim 1, further comprising, in combination, a domestic appliance including a user interface, said capacitive touch switch being provided on the user interface.

10. A user interface comprising at least one capacitive touch switch including:

a non-conductive transparent cover including a touch-sensitive area adapted to be touched by a user;

a planar light guide extending beneath the touch-sensitive area of the non-conductive transparent cover, the planar light guide including an end portion;

a capacitive electrode provided on a surface of a printed circuit board, the printed circuit board interposed between the planar light guide and the capacitive electrode; and

a light source connected to the printed circuit board adjacent the end portion of the planar light guide, wherein light generated by the light source enters the planar light guide at the end portion and is directed through the planar light guide beneath the touch-sensitive area of the non-conductive transparent cover.

11. The user interface of claim 10, wherein the at least one capacitive touch switch includes first and second, adjacent capacitive touch switches and the user interface further comprises a jumper connecting the first and second capacitive touch switch to establish a bigger touch pad area for a user.

12. A cooking appliance comprising:

a door hinged to a structure of the appliance; and

a user interface supported by the door, the user interface including at least one capacitive touch switch comprising;

a non-conductive transparent cover including a touch-sensitive area adapted to be touched by a user;

a planar light guide extending beneath the touch-sensitive area of the non-conductive transparent cover, the planar light guide including an end portion;

a capacitive electrode provided on a surface of a printed circuit board, the printed circuit board interposed between the planar light guide and the capacitive electrode; and

a light source connected to the printed circuit board adjacent the end portion of the planar light guide, wherein light generated by the light source enters the planar light guide at the end portion and is directed through the planar light guide beneath the touch-sensitive area of the non-conductive transparent cover.