Touch entry interactive cathode ray tube arrangement

• US 4,198,623 A
• Filed: 11/13/1978
• Issued: 04/15/1980
• Est. Priority Date: 11/13/1978
• Status: Expired due to Term

• Current Assignee: Sanders Associates, INC. (BAE Systems Plc)
• Original Assignee: Sanders Associates, INC. (BAE Systems Plc)
• Inventors: Hastbacka, Albin A., Misek, Victor A., Trasatti, Alphonse J., Beairsto, Robert J.
• Primary Examiner(s): Trafton, David L.
• Application Number:
  US05/960,142
• Time in Patent Office: 519 Days
• Field of Search: 340/365 P, 340/712, 178/18, 250/203 CT, 250/549, 250/548, 364/742, 364/855
• 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 display employing a horizontal and vertical grid of parallel infrared light beams in front of a cathode ray tube (CRT) face wherein a finger or other object may be placed against the face of the CRT to mark a spot thereon and the spot so marked will be detected by the interrupted beams. Infrared sources and detectors are located around the periphery of the CRT face and operate in different planes to more closely follow the curvature of the CRT face and thereby minimize parallax errors.

Claims

1. Interactive video display apparatus functioning with a video display having a non-planar display area and with associated equipment which generates signals for a display on said display area comprising:

a plurality of energy sources located along the edge of the display area of said video display and energized to send beams of energy proximate to at least a portion of said display area;

a plurality of detectors located along the edge of the display area but being spaced further therefrom than said plurality of energy sources, each of said detectors receiving at least one energy beam and providing an indication upon the received energy beams being interrupted and wherein an object touching the video display interrupts more than two energy beams at least one of which is close to the surface of said display at the point touched;

means responsive to the interrupted beam indication from ones of said detectors for providing identity signals indicating which energy beams are interrupted; and

means for processing said identity signals to choose the interrupted energy beams closest to the surface of said display area at the point touched, the identity signals of the chosen interrupted beams defining the coordinates of the video display point being touched.

2. The interactive video display apparatus of claim 1 wherein said identity signal providing means comprises:

means for periodically sampling the output of each of said detector means to determine the ambient light conditions around said video display detected by said detector means; and

means for determining if the ambient light conditions are so bright as to interfere with the operation of said interactive video display apparatus, and when said ambient light conditions are too bright providing a signal to said processing means which causes no further processing of said identity signals.

3. The invention in accordance with claim 2 further comprising:

a counter driven by a clock source;

a decoder responsive to said counter and having an output associated with each of said energy sources, said decoder outputs being sequentially and periodically energized to energize said energy sources; and

a first selector having an output associated with each of said detectors sequentially and periodically connecting each of said detectors to an output of said first selector, each of said detectors being connected to said first selector output for a first time period during part of which their associated energy sources are energized.

4. The invention in accordance with claim 3 wherein said first selector connects a selected detector to said sampling means for part of said first time period and to said identity signal providing means for the remainder of said first time period during which its associated energy source is energized.

5. The invention in accordance with claim 4 wherein plurality of energy sources each comprise a device for emitting infrared when energized.

6. Interactive video display apparatus functioning with a video display device having a non-planar display area and with associated equipment which generates signals for a display on said display area, comprising:

a first plurality of energy sources located along the edge of the display area of said video display and energized to send beams of energy relatively close to at least a portion of the surface of said non-planar display area;

a second plurality of energy sources also located along the edge of the non-planar display area of said video display and energized to send beams of energy close to at least a portion of but not touching the surface of said display area, the beams from said second plurality of energy means not being coplanar with said beams of energy from said first plurality of energy sources;

a third plurality of energy sources also located along the edge of the display area of said video display and energized to send beams of energy close to at least a portion of but not touching the surface of said display area, the beams from said third plurality of energy sources not being coplanar with said beams of energy from said first and said second energy sources, with an energy beam of one each of said first, second and third plurality of energy sources being interrupted upon touching said display area with a finger or other object;

a plurality of detectors with one detector being associated with each energy source of said first, second, and third plurality of energy sources, each detector being located on the opposite side of said display area from its associated one of said first, second or third plurality of energy sources and receiving the energy beam from the associated energy source, said detectors providing an output indication upon the received energy beam being interrupted; and

means responsive to said interrupted beam output indication from ones of said detectors upon said display area being touched for providing identity signals indicating which energy beams are interrupted.

7. The invention in accordance with claim 6 further comprising means for processing said identity signals to choose the interrupted energy beams closest to the surface of said display area at the point touched, the chosen interrupted beam identity signals defining the coordinates of the point being touched.