Browse Prior Art Database

Light-Sensitive Pen to Substitute for Finger in Laser Scanned Touch Screen

IP.com Disclosure Number: IPCOM000036042D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Garwin, RL: AUTHOR [+2]

Abstract

Disclosed is a device to enable a user's opaque finger or reflective stylus to be used indifferently in a laser-scanned touch screen, achieving the particular benefits of either. Laser-scanned touch- screen systems exist in the art in which a finger or an opaque stylus can be used to provide single-pixel accuracy, 100 points per second or more, over a display or input region of any size. While convenient and inexpensive, finger or opaque stylus (pencil, pen, toothpick, or other handy device) must not be accompanied by any other obstruction of light in the entire input area, which would be recognized by the system and all input rejected.

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Light-Sensitive Pen to Substitute for Finger in Laser Scanned Touch Screen

Disclosed is a device to enable a user's opaque finger or reflective stylus to be used indifferently in a laser-scanned touch screen, achieving the particular benefits of either. Laser-scanned touch- screen systems exist in the art in which a finger or an opaque stylus can be used to provide single-pixel accuracy, 100 points per second or more, over a display or input region of any size. While convenient and inexpensive, finger or opaque stylus (pencil, pen, toothpick, or other handy device) must not be accompanied by any other obstruction of light in the entire input area, which would be recognized by the system and all input rejected.

For long use of such input systems, particularly for large displays, it is desirable to allow the user to rest a palm or arm on the input display. For such applications prior-art systems employ a retroreflective stylus, which provides a clear signal to the two scanners so long as there is a line of sight from each to the stylus. Retroreflective material being very scarce in the environment, there is no interference from arms, palms, coffee cups, or other ordinary material on the display area.

Because the opaque-stylus ("finger") approach must use a retroreflective fence to provide a steady light signal to the scanner at all points except those obscured by the finger, such a fence provides intolerable background for the retroreflective stylus (RRS) approach. Furthermore, the RRS requires that the detector sense an increase in signal to signify the location of the...