Telegraphy – Systems – Position coordinate determination for writing
Patent
1994-04-22
1997-08-19
Chin, Stephen
Telegraphy
Systems
Position coordinate determination for writing
G08C 2100
Patent
active
056591543
ABSTRACT:
A digitizing tablet includes stacked X and Y coordinate resistance boards (X-board and Y-board) with insulating beads therebetween. A CPU controls input and grounding switches of both X- and Y-boards and a selector switch. The selector switch connects an A/D converter input to grounding electrodes of the X and Y boards. The input switch of the X-board applies a supply potential to an input electrode of the X-board while a grounding electrode of the X-board is disconnected from ground by the grounding switch. The Y-board is grounded at a grounding electrode while the input electrode of the Y-board floats. The A/D converter monitors a voltage at the grounding electrode of the X-board to detect a drop in potential from the supply potential. When contact pressure is applied to the digitizing tablet, current flows from the supply potential, through the X and Y boards via a contact point, and into ground via the Y-board grounding switch. The potential appearing at the grounding electrode of the X-board drops thus signaling contact. The CPU reads this change in potential and initiates a coordinate determination process. An alternate embodiment employs a voltage dropping resistor, in supply leads to the X and Y boards, which turns on a switching transistor when current is drawn, signaling an interrupt to the CPU, and initiating coordinate determination.
REFERENCES:
patent: 5245139 (1993-09-01), Protheroe et al.
patent: 5274362 (1993-12-01), Potvin
patent: 5324895 (1994-06-01), Inamori
Chin Stephen
Loomis Paul
SMK Corporation
LandOfFree
Method and apparatus for coordinate detection does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for coordinate detection, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for coordinate detection will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1106603