Interactive CRT with touch level set

• US 4,710,759 A
• Filed: 04/13/1987
• Issued: 12/01/1987
• Est. Priority Date: 02/22/1984
• Status: Expired due to Term

• Current Assignee: Zenith Electronics Corporation (LG Corporation)
• Original Assignee: Zenith Electronics Corporation (LG Corporation)
• Inventors: Fitzgibbon, James
• Primary Examiner(s): Brigance, Gerald L.
• Application Number:
  US07/037,079
• Time in Patent Office: 232 Days
• Field of Search: 340/712, 340/365 P, 340/365 VL, 340/766, 340/524, 340/555, 340/753, 340/754, 340/709, 340/711, 367/907, 178/18
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/0428 by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421

Abstract

A touch panel level set for a CRT including a plurality of energy paths crisscrossing the faceplate of the CRT includes a microprocessor for energizing and interrogating the energy paths on a regular basis. A specific threshold level for each energy path is regularly determined by the microprocessor and retained in its memory. The specific threshold levels are used to compare the determined threshold levels in each energy path during interrogation thereof to ascertain whether the energy paths have been interrupted. Comparison is done on an analog basis with the memory output of the microprocessor being supplied through a D/A converter.

Claims

1. In a touch control panel having a plurality of crossing energy paths and means for repetitively testing the energy levels in said paths against stored test levels for said paths to determine if an interruption, corresponding to a touch, has occurred, a method of updating the stored test levels for said paths comprising the steps of:

energizing each of said paths in sequence;

comparing the detected energy level in each of said paths with a nominal threshold level;

A. (1) if the test indicates energy is detected, testing again with a maximum threshold level;

(2) if at a maximum energy level, storing the maximum threshold level as the updated test level for that energy path;

(3) if not at a maximum energy level, increasing the nominal threshold level and testing again;

(4) continuing testing and increasing the threshold level until no energy is detected, and storing the last threshold level as the updated test level for that path;

B. (1) if the test indicates no energy detected, testing for a minimum threshold level;

(2) if at a minimum threshold level, storing the minimum threshold level as the updated test level for that path;

(3) if the threshold level is not at a minimum, decreasing the threshold level by a predetermined amount; and

(4) storing the decreased threshold level as the updated test level for that path.

2. The method of claim 1, further including the steps of:

A. (5) decreasing the threshold level by a preselected amount when a change from energy detection to no energy detection occurs; and

(6) storing the decreased threshold level as the updated test level for that path.

3. The method of claim 2, further including comparator means having one input supplied with a signal representative of the energy level in a path and another input supplied with a signal corresponding to the threshold level.

4. The method of claim 3, further including the steps of regularly and frequently repeating the steps in A and B and continually updating the stored test levels for said paths.

5. In a touch control panel system having a plurality of crossing energy paths and means for repetitively testing the energy levels in said paths against stored test levels for said paths to determine if an interruption, corresponding to a touch, has occurred and including comparator means having one input supplied with a signal representative of the energy level in a path and another input supplied with a signal corresponding to a threshold level, a method of updating the stored test levels comprising the steps of:

energizing each of said paths in sequence;

applying a signal representative of path energy level to said comparator means;

applying a nominal threshold level signal to said comparator means;

A. (1) if the comparison indicates energy detection in the path, testing again with a maximum threshold level signal applied to said comparator means;

(2) if energy is still detected, storing the maximum threshold level as the test level for that energy path;

(3) if energy is not detected, increasing the nominal threshold level and testing again;

continuing testing with increased threshold levels until no energy is detected;

(4) decreasing the threshold level by a preselected amount when a change from energy detection to no energy detection occurs; and

(5) storing the last threshold level as the updated test level for that path;

B. (1) if the comparison indicates no energy detection in the path, checking for a minimum threshold level;

(2) if at a minimum threshold level, storing the minimum threshold level as the updated test level for that path; and

(3) if the threshold level is not at a minimum, decreasing the threshold level by a predetermined amount; and

(4) storing the decreased threshold level as the updated test level for that path.