Patent ID: 7205984

Claim:
A pen input display device for making pen entry on a display panel using an input pen having an ultrasonic transmitting section, the pen input display device including at least two ultrasonic receiving sections that are in a fixed spatial relationship with the display panel, said pen input display device comprising: a distance detecting section for detecting a parameter that directly or indirectly indicates a distance of the ultrasonic transmitting section from each of the ultrasonic receiving sections and outputting a value of the parameter as a digital signal; and a received waveform control section for carrying out control of reducing a difference in level of received waveforms, using the digital signal of the value of the parameter detected by the distance detecting section, when the ultrasonic receiving sections receive an ultrasonic signal from the ultrasonic transmitting section, wherein the digital signal is a time value indicating a time for an ultrasonic signal to travel from the ultrasonic transmitting section to the ultrasonic receiving sections.