Coordinate-capturing apparatus
AssigneeOki Electric Industry Co., Ltd.
InventorKenzo Tsuji
Life of this patent
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Abstract
A coordinate-capturing apparatus suitable for inputting handwritten characters or diagrams to a computer or a printer is disclosed. The apparatus includes an ultrasonic transmitter mounted on an input pen for transmitting ultrasonic waves, two ultrasonic receivers for receiving ultrasonic waves transmitted form the ultrasonic transmitter, and a distance calculating device for calculating distances between the input pen and the two ultrasonic receivers in order to determine coordinates representing a position of the input pen on the basis of the calculated distances. The apparatus of the invention can perform coordinate detection smoothly even when the input pen moves fast, and has reduced electric power consumption in the input pen to increase the life-span of a battery included in the input pen.
Claims20
A coordinate-capturing apparatus comprising:
- an ultrasonic transmitter mounted on an input pen to be in contact with a medium for transmitting ultrasonic waves;
- a first and a second ultrasonic receivers for receiving ultrasonic waves transmitted form said ultrasonic transmitter;
- a distance calculating device for calculating distances between said input pen and said first and said second ultrasonic receivers when a specific condition is satisfied;
- a coordinate calculating device for calculating coordinates representing a position of said input pen on the basis of said distances calculated by said distance calculating device;
- and
- a distance variation calculating device for calculating variations of said distances between said input pen and said first and second ultrasonic receivers on the basis of time periods between receptions of an ultrasonic wave transmitted from said ultrasonic transmitter at a first time by said first and second ultrasonic receivers respectively and receptions of an ultrasonic wave transmitted from said ultrasonic transmitter at a second time by said first and second ultrasonic receivers respectively;
- said distance calculating device calculating, on the basis of said distances calculated when said specific condition is satisfied and said variations of said distances calculated by said distance variation calculating device, distances between said input pen and said first and second ultrasonic receivers when said specific condition is not satisfied.
Dependencies are inferred from the claim text.