US5341155A
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US
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Method for correction of position location indicator for a large area display system
Assignee: Xerox Corp
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Filing: 1992-04-06
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Granted: 1994-08-23
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Expires: 2012-04-06
Abstract
Abstract In a large area display system, multiple persons may work together with multiple input devices for supplying and receiving information in an interactive system with a single large area display. The large area display system comprises a screen wherein computer generated information is projected upon one side of the screen, and users interact with the computer from the opposite side of the the screen. Data coordinates for an input device corresponding to a pseudo image sensed by the receiving subsystem electronics are provided to the controlling computer. The input data coordinates from the pseudo image are normalized for variations due to frequency dependence and electronic drift. The normalized data coordinates are looked up in a calibration table to account for distortion in the pseudo image detection electronics. Screen coordinates corresponding to pixel locations on the large area screen are found by interpolation from the data From the calibration table. The calibration table is prepared off-line, based on a bicubic spline interpolating function which is then compressed using a delta compression scheme. During on-line operation of the system, screen coordinates are looked-up directly from the compressed table. The screen coordinates are then jitter smoothed to provide a smooth path of response closely conforming to original input locations. The jitter smoothing method uses an exponential function based on the magnitude of the change in the position of the input.
Inventors
- 👤 Scott A. Elrod
- 👤 Brent B. Welch
- 👤 David Goldberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:11
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/01; G06F3/03; G06F3/041; G06F3/042; G06F3/0425; G06F3/033; G06F3/038; G06F3/0386
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
182 words
In a projection display system comprising a screen wherein computer generated information is projected upon one side of the screen and a user interacts with the computer by projecting a modifiable light image having one of a number of identifiable frequencies towards an input position upon the opposite side of the screen, a position location indicator representative of the input position is projected onto said one side by side computer, and further comprising an illumination detector which transmits pseudo image coordinates of the input position to said computer, a method of correcting the position of said pseudo image coordinates and closely conforming said position location indicator with said input position comprising steps of: detecting said pseudo image coordinates; adjusting said pseudo image coordinates to normalize for detector distortions due to frequency of said projected light image; adjusting said pseudo image coordinates to normalize for detector distortions due to electronic signal drift; and adjusting said pseudo image coordinates for detector distortions due to screen voltage grid distortion, wherein coordinates of said position location indicator are determined corresponding to said adjusted pseudo image coordinates.
Claim 2
Dependent Claim
182 words
In a projection display system comprising a screen wherein computer generated information is projected upon one side of the screen and a user interacts with the computer by projecting a modifiable light image having one of a number of identifiable frequencies towards an input position upon the opposite side of the screen, a position location indicator representative of the input position is projected onto said one side by side computer, and further comprising an illumination detector which transmits pseudo image coordinates of the input position to said computer, a method of correcting the position of said pseudo image coordinates and closely conforming said position location indicator with said input position comprising steps of: detecting said pseudo image coordinates; adjusting said pseudo image coordinates to normalize for detector distortions due to frequency of said projected light image; adjusting said pseudo image coordinates to normalize for detector distortions due to electronic signal drift; and adjusting said pseudo image coordinates for detector distortions due to screen voltage grid distortion, wherein coordinates of said position location indicator are determined corresponding to said adjusted pseudo image coordinates.
Claim 3
Dependent Claim
35 words
The method of claim 1, wherein said voltage grid distortion adjusting step further comprises finding coordinates for said position location indicator corresponding to said adjusted pseudo image coordinates using a table of compressed calibration data.
Claim 4
Dependent Claim
41 words
The method of claim 2, wherein said voltage grid distortion adjusting step further comprises: finding calibrated coordinates surrounding said pseudo image coordinates in said table of compressed calibration data; and interpolating between said calibrated coordinates to said position location indicator coordinates.
Claim 5
Dependent Claim
204 words
In a projection display system comprising a screen wherein computer generated information is projected upon one side of the screen and a user interacts with the computer by projecting a modifiable light image having one of a number of identifiable frequencies towards an input position upon the opposite side of the screen, a position location indicator representative of the input position is projected onto said one side by said computer, and further comprising an illumination detector which transmits pseudo image coordinates of said input position to said computer, a method of correcting the position of said pseudo image coordinates and closely conforming a corrected position location indicator with the input position comprising steps of: detecting said pseudo image coordinates; adjusting said pseudo image coordinates to normalize for detector distortions due to frequency of said projected light image; adjusting said pseudo image coordinates to normalize for detector distortions due to electronic signal drift; adjusting said pseudo image coordinates for detector distortions due to screen voltage grid distortion; determining a magnitude of change in distance between said adjusted pseudo image coordinates and a previous position of said position location indicator; and adjusting said corrected position of said position location indicator based on said magnitude of change.
Claim 6
Dependent Claim
204 words
In a projection display system comprising a screen wherein computer generated information is projected upon one side of the screen and a user interacts with the computer by projecting a modifiable light image having one of a number of identifiable frequencies towards an input position upon the opposite side of the screen, a position location indicator representative of the input position is projected onto said one side by said computer, and further comprising an illumination detector which transmits pseudo image coordinates of said input position to said computer, a method of correcting the position of said pseudo image coordinates and closely conforming a corrected position location indicator with the input position comprising steps of: detecting said pseudo image coordinates; adjusting said pseudo image coordinates to normalize for detector distortions due to frequency of said projected light image; adjusting said pseudo image coordinates to normalize for detector distortions due to electronic signal drift; adjusting said pseudo image coordinates for detector distortions due to screen voltage grid distortion; determining a magnitude of change in distance between said adjusted pseudo image coordinates and a previous position of said position location indicator; and adjusting said corrected position of said position location indicator based on said magnitude of change.
Claim 7
Dependent Claim
69 words
The method of claim 4, wherein said adjustment based on said magnitude of change in distance is smaller than said magnitude of change when said magnitude of change in distance is less than a change threshold distance, and said adjustment based on said magnitude of change is equal to said magnitude of change in distance when said magnitude of change in distance is greater than said change threshold distance.
Claim 8
Dependent Claim
201 words
In a projection display system comprising a screen wherein computer generated information is projected upon one side of the screen and a user interacts with the computer by projecting a light image at a function identifying frequency at an input position upon the opposite side of the screen, a position location indicator representative of the input position is projected onto said one side by said computer, and further comprising an illumination detector which transmits pseudo image coordinates of the input position to said computer, a method of correcting the position of said pseudo image coordinates and closely conforming said position location indicator with said input position comprising steps of: entering data indicative of user input at locations in each of four corners of a large area display for a first frequency; entering function identifying frequency data indicative of user input at locations in each of four corners of the large area display for the function identifying frequency; determining a normalizing factor based on said first frequency data and said function identifying frequency data; detecting pseudo image coordinates of an input position; and modifying said pseudo image coordinates in response to said normalizing factor to determine coordinates of said position location indicator.
Claim 9
Dependent Claim
201 words
In a projection display system comprising a screen wherein computer generated information is projected upon one side of the screen and a user interacts with the computer by projecting a light image at a function identifying frequency at an input position upon the opposite side of the screen, a position location indicator representative of the input position is projected onto said one side by said computer, and further comprising an illumination detector which transmits pseudo image coordinates of the input position to said computer, a method of correcting the position of said pseudo image coordinates and closely conforming said position location indicator with said input position comprising steps of: entering data indicative of user input at locations in each of four corners of a large area display for a first frequency; entering function identifying frequency data indicative of user input at locations in each of four corners of the large area display for the function identifying frequency; determining a normalizing factor based on said first frequency data and said function identifying frequency data; detecting pseudo image coordinates of an input position; and modifying said pseudo image coordinates in response to said normalizing factor to determine coordinates of said position location indicator.
Claim 10
Dependent Claim
197 words
In a projection display system comprising a screen wherein computer generated information is projected upon one side of the screen and a user interacts with the computer by projecting a modifiable light image at a second input position upon the opposite side of the screen, a position location indicator representative of a first input position is projected onto said one side at a first position by said computer, and further comprising an illumination detector which transmits pseudo image coordinates of said second input position to said computer, a method of correcting the position of said pseudo image coordinates and closely conforming said position location indicator with said second input position comprising steps of: entering data indicative of the coordinates of said first position of the position location indicator representative of the first input position; detecting pseudo image coordinates of said second input position; determining magnitude of a difference in position between said pseudo image coordinates and coordinates of said first position of the position location indicator; determining a change factor in response to said difference magnitude; and determining a second position of said position location indicator representative of said second input position according to said change factor.
Claim 11
Dependent Claim
197 words
In a projection display system comprising a screen wherein computer generated information is projected upon one side of the screen and a user interacts with the computer by projecting a modifiable light image at a second input position upon the opposite side of the screen, a position location indicator representative of a first input position is projected onto said one side at a first position by said computer, and further comprising an illumination detector which transmits pseudo image coordinates of said second input position to said computer, a method of correcting the position of said pseudo image coordinates and closely conforming said position location indicator with said second input position comprising steps of: entering data indicative of the coordinates of said first position of the position location indicator representative of the first input position; detecting pseudo image coordinates of said second input position; determining magnitude of a difference in position between said pseudo image coordinates and coordinates of said first position of the position location indicator; determining a change factor in response to said difference magnitude; and determining a second position of said position location indicator representative of said second input position according to said change factor.
Claim 12
Dependent Claim
23 words
The method of claim 7 wherein said step of determining a change factor comprises using an exponential function based on said difference magnitude.
Claim 13
Dependent Claim
217 words
In a projection display system comprising a screen wherein computer generated information is projected upon one side of the screen and a user interacts with the computer by projecting a modifiable light image at a second input location upon the opposite side of the screen, a position location indicator representative of a first input location is projected at a first position onto said one side, and further comprising an illumination detector which transmits pseudo image coordinates of the input position to said computer, a method of correcting the position of said pseudo image coordinates and closely conforming said position location indicator with said input position comprising steps of: entering data indicative of the coordinates of said first position of the position location indicator representative of the first input location; detecting pseudo image coordinates of the input position; determining magnitude of difference in position between said pseudo image coordinates and coordinates of said first position of the position location indicator; and determining a change in the position of the position location indicator in response to said difference magnitude, wherein said change in position is smaller than said difference magnitude when said difference magnitude is less than a change threshold, and said change is equal to said difference magnitude when said difference magnitude is greater than said change threshold.
Claim 14
Dependent Claim
217 words
In a projection display system comprising a screen wherein computer generated information is projected upon one side of the screen and a user interacts with the computer by projecting a modifiable light image at a second input location upon the opposite side of the screen, a position location indicator representative of a first input location is projected at a first position onto said one side, and further comprising an illumination detector which transmits pseudo image coordinates of the input position to said computer, a method of correcting the position of said pseudo image coordinates and closely conforming said position location indicator with said input position comprising steps of: entering data indicative of the coordinates of said first position of the position location indicator representative of the first input location; detecting pseudo image coordinates of the input position; determining magnitude of difference in position between said pseudo image coordinates and coordinates of said first position of the position location indicator; and determining a change in the position of the position location indicator in response to said difference magnitude, wherein said change in position is smaller than said difference magnitude when said difference magnitude is less than a change threshold, and said change is equal to said difference magnitude when said difference magnitude is greater than said change threshold.
Claim 15
Dependent Claim
58 words
The method of claim 9 wherein said step of determining a change in the position of the position location indicator further comprises determining said change in position by an exponential function based on said difference magnitude, wherein said change threshold is based upon the difference magnitude which causes the value of the exponential function to equal approximately one.
Claim 16
Dependent Claim
190 words
In a projection display system comprising a screen wherein computer generated information is projected upon one side of the screen and a user interacts with the computer by projecting a light image at an input position upon the opposite side of the screen, a position location indicator representative of the input position is projected onto said one side by said computer, and further comprising an illumination detector which transmits pseudo image coordinates of the input position to said computer, a method of correcting the position of said pseudo image coordinates and closely conforming said position location indicator with said input position comprising steps of: detecting said pseudo image coordinates; adjusting said pseudo image coordinates to normalize for detector distortions due to electronic signal drift; and adjusting said pseudo image coordinates for detector distortions due to screen voltage grid distortion, wherein said screen voltage grid adjustment is determined by finding data point coordinates surrounding said pseudo image coordinates from a compressed table of data based on an inverse spline function fitted to a plurality of calibration data points, and interpolating to determine coordinates of the position of said position location indicator.
Claim 17
Dependent Claim
190 words
In a projection display system comprising a screen wherein computer generated information is projected upon one side of the screen and a user interacts with the computer by projecting a light image at an input position upon the opposite side of the screen, a position location indicator representative of the input position is projected onto said one side by said computer, and further comprising an illumination detector which transmits pseudo image coordinates of the input position to said computer, a method of correcting the position of said pseudo image coordinates and closely conforming said position location indicator with said input position comprising steps of: detecting said pseudo image coordinates; adjusting said pseudo image coordinates to normalize for detector distortions due to electronic signal drift; and adjusting said pseudo image coordinates for detector distortions due to screen voltage grid distortion, wherein said screen voltage grid adjustment is determined by finding data point coordinates surrounding said pseudo image coordinates from a compressed table of data based on an inverse spline function fitted to a plurality of calibration data points, and interpolating to determine coordinates of the position of said position location indicator.
Claim 18
Dependent Claim
62 words
The projection display system of claim 11, wherein said compressed table of data further comprises a variably sized set of bit fields of packed integers, each value in the table representing a delta change in magnitude from one calibration point to the previous calibration point in the same row, each row size being determined by the maximum delta value in the row.
Claim 19
Dependent Claim
29 words
The projection display system of claim 12, wherein said compressed table of data further has rows describing horizontal coordinates values and rows describing vertical coordinate values that are interleaved.
References Cited (Backward Citations)
US3885096A
Cited
US4295198A
Cited
US4514688A
Cited
US4679241A
Cited
EP0074703A2
Cited
US4456787A
Cited
US4575581A
Cited
JPS60230228A
Cited
US4737773A
Cited
US4650926A
Cited
US4678869A
Cited
WO1991001543A1
Cited
WO1992005483A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-08-22 | 1998-02-21 | 1998-08-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-22 | 2002-02-21 | 2002-08-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-22 | 2006-02-21 | 2006-08-23 | $7700.00 | Window Closed / Lapsed |