Patent US5107253A successfully refreshed from Google Patents.
US5107253A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stylus position detection system for optical touch panel
Assignee: Tektronix Inc
•
Filing: 1989-11-13
•
Granted: 1992-04-21
•
Expires: 2009-11-13
Abstract
Abstract A detection circuit (30, 32) for carrying out a rapid search technique for locating the position of a stylus (12) relative to a display screen (10). A microprocessor (34) and related components select a group of light detectors (20, 28) that are positioned near the display screen (10). The summed output current of the selected group of detectors (20, 28) is monitored to determine whether the output of any detector in the selected group is reduced because of the presence of a stylus (12). Whenever the selected group shows such reduction in output current, that selected groups is divided into two subgroups. The subgroup having reduced current output due to the presence of the stylus (12) is further divided until the particular detector(s) having reduced output current is found, the position of the detector is correlated to the location of the stylus (12) relative to the screen (10).
Inventors
- 👤 R. David Meadows
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:27
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/01; G06F3/03; G06F3/041; G06F3/042; G06F3/0421
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
186 words
In an optical touch panel system having a light source for directing light toward plural light detector elements that each generate an analog output signal representing the amount of light received from the light source, an amount of light less than a predetermined threshold representing a selected location on the touch panel, a method for identifying the selected location, comprising: designating a group of the light detectors as a sampling group; forming a summed output signal with a magnitude representing a sum of the amplitudes of the analog output signals generated by the light detector elements in the sampling group; comparing the summed output signal to a reference output signal having a magnitude representing a sum of the amplitudes of the analog output signals generated by the light detector elements in the sampling group when they all receive the light from the light source; and whenever the magnitude of the summed output signal differs from the magnitude of the reference output signal by more than a predetermined signal difference, dividing the sampling group of light detectors into a subgroup and designating it as a sampling group.
Claim 2
Dependent Claim
186 words
In an optical touch panel system having a light source for directing light toward plural light detector elements that each generate an analog output signal representing the amount of light received from the light source, an amount of light less than a predetermined threshold representing a selected location on the touch panel, a method for identifying the selected location, comprising: designating a group of the light detectors as a sampling group; forming a summed output signal with a magnitude representing a sum of the amplitudes of the analog output signals generated by the light detector elements in the sampling group; comparing the summed output signal to a reference output signal having a magnitude representing a sum of the amplitudes of the analog output signals generated by the light detector elements in the sampling group when they all receive the light from the light source; and whenever the magnitude of the summed output signal differs from the magnitude of the reference output signal by more than a predetermined signal difference, dividing the sampling group of light detectors into a subgroup and designating it as a sampling group.
Claim 3
Dependent Claim
17 words
The method of claim 1 in which the summed output signal is formed as an analog signal.
Claim 4
Dependent Claim
36 words
The method of claim 2 in which the reference output signal is in a digital signal format and the summed output signal is converted to the digital signal format for comparison with the reference output signal.
Claim 5
Dependent Claim
24 words
The method of claim 1 in which each subgroup divided from a sampling group includes one-half the light detector elements of the sampling group.
Claim 6
Dependent Claim
181 words
In an optical touch panel system having a light source for directing light toward plural light detector elements that each generate an analog output signal representing the amount of light received from the light source, an amount of light less than a predetermined threshold representing a selected location on the touch panel, the improvement comprising: summing means for forming a summed output signal with a magnitude representing a sum of the amplitudes of the analog output signals generated by a group of light detector elements designated as a sampling group; and control means for comparing the summed output signal to a reference output signal having a magnitude representing a sum of the amplitudes of the analog output signals generated by the light detector elements in the sampling group when they all receive the light from the light source and, whenever the magnitude of the summed output signal differs from the magnitude of the reference output signal by more than a predetermined signal difference, dividing the sampling group of light detector elements into a subgroup and designating it as a sampling group.
Claim 7
Dependent Claim
181 words
In an optical touch panel system having a light source for directing light toward plural light detector elements that each generate an analog output signal representing the amount of light received from the light source, an amount of light less than a predetermined threshold representing a selected location on the touch panel, the improvement comprising: summing means for forming a summed output signal with a magnitude representing a sum of the amplitudes of the analog output signals generated by a group of light detector elements designated as a sampling group; and control means for comparing the summed output signal to a reference output signal having a magnitude representing a sum of the amplitudes of the analog output signals generated by the light detector elements in the sampling group when they all receive the light from the light source and, whenever the magnitude of the summed output signal differs from the magnitude of the reference output signal by more than a predetermined signal difference, dividing the sampling group of light detector elements into a subgroup and designating it as a sampling group.
Claim 8
Dependent Claim
38 words
The system of claim 5 in which the summing means includes a summing amplifier for forming an analog summed output signal and an analog-to-digital converter for converting the analog summed output signal to a digital summed output signal.
Claim 9
Dependent Claim
20 words
The system of claim 6 in which the control means includes a memory circuit for storing the reference output signal.
Claim 10
Dependent Claim
24 words
The system of claim 5 in which the control means includes a microprocessor for comparing the summed output signal and the reference output signal.
References Cited (Backward Citations)
US3775560A
Cited
US3764813A
Cited
US4243879A
Cited
US4645920A
Cited
US4684801A
Cited
US4722259A
Cited
US4766425A
Cited
US4845346A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-04-21 | 1995-10-21 | 1996-04-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-04-21 | 1999-10-21 | 2000-04-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-04-21 | 2003-10-21 | 2004-04-21 | $7700.00 | Window Closed / Lapsed |