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A Non-light Bleeding Illuminated Capacitive Button Assembly

IP.com Disclosure Number: IPCOM000035628D
Publication Date: 2005-Jan-27
Document File: 3 page(s) / 223K

Publishing Venue

The IP.com Prior Art Database

Related People

Chris Silk: INVENTOR

Abstract

Light bleeding is when the light of one illuminated button area leaks into a neighboring button area. Illuminated, capacitive touch pads available through Synaptics usually consist of a single light guide that covers the entire input area of the touch pad. (The touch pad often includes a printed circuit board (PCB) with sensor electrodes and circuitry.) The light guide can be a thin, transparent plate that is illuminated by side firing LED's. Occasionally there is a desire for unconnected, individual button areas to be illuminated using a single light guide. This desired design usually has the undesirable 'light bleeding' effect. The design described in this document uses several light panels to illuminate individual button areas. Using methods such as Global Lighting Technology's (GLT) MicroLens(TM) technology also enables each panel can have large logos and text introduced.

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A Non-light Bleeding Illuminated Capacitive Button Assembly Chris Silk

A Non-light Bleeding Illuminated Capacitive Button Assembly

1. Inventor(s): Chris Silk
2. Synaptics Incorporated, San Jose, CA, USA

3. Short Summary

Light bleeding is when the light of one illuminated button area leaks into a neighboring button area. Illuminated, capacitive touch pads available through Synaptics usually consist of a single light guide that covers the entire input area of the touch pad. (The touch pad often includes a printed circuit board (PCB) with sensor electrodes and circuitry.) The light guide can be a thin, transparent plate that is illuminated by side firing LED's. Occasionally there is a desire for unconnected, individual button areas to be illuminated using a single light guide. This desired design usually has the undesirable 'light bleeding' effect. The design described in this document uses several light panels to illuminate individual button areas. Using methods such as Global Lighting Technology's (GLT) MicroLensTM technology also enables each panel can have large logos and text introduced.

Figure 1: Plan view of an illuminated button module.

4. Some Problems Solved

* The assembly no longer requires a separate covering typically placed over touch pads (e.g. a polyester, insulative cover sheet such as a Mylar® sheet), which eliminates assembly placement accuracy issues (text and logo info can be placed on the Light Panel).

* Each Light Panel is isolated from its neighboring Light Panel by the Frame. This eliminates 'light bleeding'.

Capacitive Sensor

PCB

Illuminated

Light Panel capacitive buttons

Plastic, non- transparent 'Frame'

Copyright © 2005 Synaptics Incorporated, All Rights Reserved. Page: 1 of 3

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A Non-light Bleeding Illuminated Capacitive Button Assembly Chris Silk

5. General Description

The design described in this document is based around a single piece light guide. In one embodiment, the single piece light guide is replaced with a non-transparent injection molded 'Frame' with additional window apertures. The Frame can be fashioned from material such as ABS (Acrylonitrile Butadiene Styrene) or PC (Polycarbonate). The window apertures have been introduced for the insertion of illuminated buttons. Each button consists of a transparent injection molded Acrylic Light Panel. The Light Panels are retained and sandwiched between the Frame and the Back Reflector. The Light Panels incorporate a technology such as the MicroLensTM technology, which introduces text or/and logos to the Light Panel and eliminates the need for a separate covering such as a Mylar® sheet. The micro-lens features can be molded on the contact surface (depending on wear tests) or the rear surface. The Back Reflector is preferably a dark color, such as black, so that...