Method of correcting skew between a digitizer and a digital display
First Claim
Patent Images
1. The method of producing image position signals lcd-- x and lcd-- y for a display device comprising the steps of:
- mounting a digitizer in fixed relation to said display device;
said digitizer being provided with touch sensing means for generating position signals touch-- x and touch-- y representing the position of a point at which said digitizer has been touched,establishing two skew constants s-- x and s-- y and two offset constants b-- x and b-- y respectively representing the skew angle and the offset distance between said digitizer and said display device,establishing two scale constants m-- x and m-- y representing scale differences between said stylus position signals and said image drive signals, andgenerating said image position signals according to the equations;
space="preserve" listing-type="equation">lcd.sub.-- x=m.sub.-- x * touch.sub.-- x+s.sub.-- x * touch.sub.-- y+b.sub.-- xand
space="preserve" listing-type="equation">lcd.sub.-- y=m.sub.-- y * touch.sub.-- y+s.sub.-- y * touch.sub.-- x+b.sub.-- y
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Abstract
A method of producing an image drive signal which is free of skew. Disclosure is made of a point of sale merchandising system having a transparent digitizer mounted on an LCD module. A stylus is used to draw a signature on the digitizer, and the signature is displayed on the LCD module in registration with the moving stylus. Skew effects are eliminated by performing a mapping transformation using a set of 6 transformation constants. These constants are derived from data obtained while placing the stylus over three reference spots on the display.
34 Citations
8 Claims
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1. The method of producing image position signals lcd-- x and lcd-- y for a display device comprising the steps of:
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mounting a digitizer in fixed relation to said display device;
said digitizer being provided with touch sensing means for generating position signals touch-- x and touch-- y representing the position of a point at which said digitizer has been touched,establishing two skew constants s-- x and s-- y and two offset constants b-- x and b-- y respectively representing the skew angle and the offset distance between said digitizer and said display device, establishing two scale constants m-- x and m-- y representing scale differences between said stylus position signals and said image drive signals, and generating said image position signals according to the equations;
space="preserve" listing-type="equation">lcd.sub.-- x=m.sub.-- x * touch.sub.-- x+s.sub.-- x * touch.sub.-- y+b.sub.-- xand
space="preserve" listing-type="equation">lcd.sub.-- y=m.sub.-- y * touch.sub.-- y+s.sub.-- y * touch.sub.-- x+b.sub.-- y - View Dependent Claims (2, 3)
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4. The method of producing image position signals lcd-- x and lcd-- y for a display device comprising the steps of:
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mounting a digitizer in fixed relation to said display device;
said digitizer being provided with moveable stylus means and stylus sensing means connected to said stylus means for generating stylus position signals touch-- x and touch-- y representing the position of the tip of said stylus relative to said digitizer,establishing two skew constants s-- x and s-- y and two offset constants b-- x and b-- y respectively representing the skew angle and the offset distance between said digitizer and said display device, establishing two scale constants m-- x and m-- y representing scale differences between said stylus position signals and said image drive signals, and generating said image drive signals by solving the equations;
space="preserve" listing-type="equation">lcd.sub.-- x=m.sub.-- x * touch.sub.-- x+s.sub.-- x * touch.sub.-- y+b.sub.-- xand
space="preserve" listing-type="equation">lcd.sub.-- y=m.sub.-- y * touch.sub.-- y+s.sub.-- y * touch.sub.-- x+b.sub.-- y - View Dependent Claims (5, 6)
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7. In a user activated terminal for the entry of transaction-related data comprising display means responsive to an image drive signal for displaying transaction-related data, a transparent panel mounted above said display surface in fixed but skewed relation thereto, a stylus electrically coupled to said panel and adapted for guided movement across the surface thereof, digitizing means connected to said panel and to said stylus for generating a position signal representing the position of said stylus relative to said panel, and computing means connected to said digitizing means for receiving said positioning signal and responsive thereto for generating said image drive signal;
- the method of producing said image drive signal comprising the steps of;
establishing the coordinates (touch-- x1,touch-- y1); (touch-- x2,touch-- y2); and
(touch-- x3,touch-- y3), for three touch points on said panel which are in registration with three reference points on said display means having coordinates (lcd-- x1,lcd-- y1);(lcd-- x2,lcd-- y2); and
(lcd-- x3,lcd-- y3)using the coordinates of said touch points and said reference points to establish two offset constants b-- x &
b-- y, two scale constants m-- x &
m-- y, and two skew constants s-- x &
s-- y such that;
##EQU4## storing all of said constants, supplying the coordinates touch-- x and touch-- y of an arbitrary point on said panel to said computing means, andcalculating coordinate values lcd-- x and lcd-- y for said image signal by causing said computing means to solve the equations;
space="preserve" listing-type="equation">lcd.sub.-- x=m.sub.-- x * touch.sub.-- x+s.sub.-- x * touch.sub.-- y+b.sub.-- xand
space="preserve" listing-type="equation">lcd.sub.-- y=m.sub.-- y * touch.sub.-- y+s.sub.-- y * touch.sub.-- x+b.sub.-- y. - View Dependent Claims (8)
- the method of producing said image drive signal comprising the steps of;
Specification