EP0364884A2
Expired / Lapsed
EP
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Detection system for optical touch panel
Assignee: Tektronix Inc
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Filing: 1989-10-12
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Granted: —
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Expires: 2009-10-12
Abstract
Abstract The system employs a coherent detection method for detecting beam interruption between the corresponding emitters (16, 24) and detectors (20, 28) of optical touch panel components that are mounted around a display screen (10). The emitted light signals (17, 25) are modulated coherent with a reference signal. The output signals of the detectors (20, 28) are demodulated coherent with the same reference signal. The demodulated output signals are processed to measure the correlation with the modulated emitted signals. A low correlation indicates the emitted beam was interrupted by a stylus (12) placed near the display screen (10).
Inventors
- 👤 Robert D. Meadows
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 16:52
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/01; G06F3/03; G06F3/041; G06F3/042; G06F3/0421; G09; G09B; G09B7/00; G09B7/06; G09B7/063
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
169 words
A detection system for an optical touch panel comprising: (a) an array of light-emitting elements mountable along one side of a display screen; (b) drive circuit means associated with the light-emitting elements for activating the light-emitting elements to emit light signals across the screen; (c) an array of light-detecting elements mountable along the side of the screen opposite the light-emitting elements, each light-detecting element corresponding to an opposing light-emitting element and producing a corresponding output signal in response to receiving a light signal from the light-emitting element; (d) detection circuit means for detecting the output signals of the light-detecting elements; and (e) coherent detecting means associated with the drive circuit means and the detection circuit means for modulating the light signals coherent with a reference signal and for demodulating the corresponding output signals coherent with the reference signal, and for processing the demodulated output signals to produce a correlation signal that is indicative of the extent of correlation between each modulated light signal and the associated demodulated output signal.
Claim 2
Dependent Claim
169 words
A detection system for an optical touch panel comprising: (a) an array of light-emitting elements mountable along one side of a display screen; (b) drive circuit means associated with the light-emitting elements for activating the light-emitting elements to emit light signals across the screen; (c) an array of light-detecting elements mountable along the side of the screen opposite the light-emitting elements, each light-detecting element corresponding to an opposing light-emitting element and producing a corresponding output signal in response to receiving a light signal from the light-emitting element; (d) detection circuit means for detecting the output signals of the light-detecting elements; and (e) coherent detecting means associated with the drive circuit means and the detection circuit means for modulating the light signals coherent with a reference signal and for demodulating the corresponding output signals coherent with the reference signal, and for processing the demodulated output signals to produce a correlation signal that is indicative of the extent of correlation between each modulated light signal and the associated demodulated output signal.
Claim 3
Dependent Claim
69 words
The system of claim 1 further including latch means operable upon receipt of an enabling signal for storing positional data corresponding to each activated light-emitting element in the array, the coherent detecting means including correlation signal processing means for comparing the value of the correlation signal with a preselected reference level and for selectively directing an enabling signal to the latch means depending upon the results of the comparison.
Claim 4
Dependent Claim
13 words
The system of claim 1 wherein the light emitting elements emit visible light.
References Cited (Backward Citations)
No citation records indexed.
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