RECEIVER, POSITION DETECTION DEVICE FOR ELECTRONIC PEN, POSITION DISPLAY SYSTEM FOR ELECTRONIC PEN, AND ULTRASONIC WAVE RECEIVING METHOD FOR RECEIVER

摘要

PROBLEM TO BE SOLVED: To provide a receiver which detects a current position of an electronic pen correctly, a position detection device for an electronic pen, a position display system for an electronic pen, and an ultrasonic wave receiving method for the receiver.

SOLUTION: The receiver includes; an infrared ray receiving circuit which receives an infrared signal from the electronic pen; an ultrasonic wave receiving circuit having an ultrasonic sensor which receives an ultrasonic signal from the electronic pen; and a detection circuit which detects a generation position of the infrared signal and the ultrasonic signal using difference in arrival time of the infrared signal and the ultrasonic signal. The ultrasonic wave receiving circuit has a filter property for amplifying the same frequency band as the ultrasonic signal of an output signal of the ultrasonic sensor and an amplification factor which makes a superimposed noise of the output signal equal or below a predetermined level, and equipped with a first amplifier to amplify the output signal and a second amplifier to amplify further the amplified signal by the first amplifier.

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