To solve a problem that a conventional handwriting input system has such defects that an electronic pen has respective transmission circuits for transmitting an ultrasonic signal and an electromagnetic signal, and thus involves large power consumption, resulting in short continuous use hours.
At least one ultrasonic reception section and at least one reflection wall are provided (totaling at least three of them), and a signal reflected on the reflection wall is taken as a signal received by a virtual ultrasonic reception section located at a mirror image position with respect to the reflection wall. From differences of arrival times of ultrasonic signals to the three or more ultrasonic reception sections including at least one virtual ultrasonic reception section, positional coordinate data of the electronic pen is calculated, so that power consumption of the handwriting input system can be reduced.
| WO/2017/048068 | ELECTROMAGNETIC INTERFERENCE SIGNAL DETECTION |
| JPH11237950 | ULTRASONIC DIGITIZER DEVICE |
| JPH06197199 | PICTURE INPUT DEVICE |
KADOI HIDEO
OSAWA SHIGERU
OZAWA KINICHI
