Touch pad using a non-electrical deformable pressure sensor

• US 6,788,295 B1
• Filed: 11/20/2001
• Issued: 09/07/2004
• Est. Priority Date: 05/26/1999
• Status: Expired due to Fees

• Current Assignee: Nitta Corporation
• Original Assignee: Tactex Controls Inc.
• Inventors: Inkster, Robert D.
• Primary Examiner(s): LAO, LUN YI
• Application Number:
  US09/979,134
• Time in Patent Office: 1,022 Days
• Field of Search: 178/18-1-, 178/19-1-, 345/173-183, 341/34, 250/227.14, 250/227.15, 250/227.16
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

A touch pad for controlling electronic equipment includes a deformable touch surface and a compressible pad body in contact with the touch surface. The compressible body is formed from a material which scatters or diffuses light within the material. Multiple sources of light or other wave energy are directed into the interior of the substrate to form multiple illuminated cells inside the pad body. Each illuminated cell forms an integrated cavity within the pad body. A detector in communication with the compressible material detects light intensity within the integrated cavity. A processor receives signals from the detector and converts the signals into useable information relating to the position of regions of compression of the pad.

Claims

1. A touch pad input device for actively controlling the operation of an electronic apparatus by hand movement of an operator, comprising:

a flat, resilient pad body having means to detect the position of at least one indentor bearing down on the pad body controlled by hand movement of an operator and means to convert such localized pressure into an electronic control signal, characterized by;

said pad body comprising a resilient light translucent material having light scattering centers generally uniformly distributed therein;

an array of light emitter and receiver pairs positioned adjacent to and terminating in a staggered lengthwise relationship relative to the other and being in operative communication with said pad body, said emitters each for transmitting light within said pad body thereby forming an optical cavity defined by a region of fully scattered light within said pad body, said receivers each for receiving light within said optical cavity for detecting the intensity of said scattered light, said emitter and receiver pairs forming an array of adjacent cells each defined by an optical cavity within said pad body, each cell being in communication with one of said emitters and receivers, wherein localized compression of said pad by the finger of a user results in an increase in scattered light intensity within at least one of said cells to detect pressure from the finger to determine the position of the finger on said pad; and

signal processing means for receiving light intensity information from said receivers, translating said information into a signal indicative of the location at which said pad is compressed, and generating an electronic signal for control of the operation of an electronic apparatus responsive to the position of said at least one indentor on said pad body.

2. The touch pad input device of claim 1, wherein said touch pad further includes a surface membrane associated with said pad body, said membrane having dimples facing convexly towards and overlying said optical cavities and adapted to deform said optical cavities upon compression of said surface membrane against said pad body.

3. The touch pad input device of claim 2, wherein said optical cavities intensify light illuminated from said light emitters for detection by said means to detect.

4. The touch pad input device of claim 3, wherein said array is a planar configuration and said optical cavities are of a higher concentration of optical cavities along a first horizontal axis than along a second horizontal axis perpendicular to said first axis.

5. The touch pad input device of claim 4, wherein said signal processing means further includes a processing means for receiving light intensity information from said means to detect and translating said light intensity information into a signal indicative of a specified pad region and pressure applied to said specified pad region.

6. The touch pad input device of claim 5, wherein said light intensity is received sequentially by said receivers and said processing means further includes means for resolving said light received sequentially by said light receivers from said light emitters.

7. The touch pad input device of claim 6, wherein said electrical device is responsive to said signal which specifies said pad region and said pressure applied to said specified pad regions.

8. The touch pad input device of claim 7, wherein the total number of means to detect are fewer than the total number of said light receivers.