| 摘要 |
<p>PURPOSE:To enable automatic outputting with digital information when the power supply voltage of an input pen is lowered by modulating the osicllation frequency of an AC signal generator corresponding to the output of a power supply voltage drop monitoring circuit inside the input pen, discriminating a received signal at a tablet with a signal processing part and digitally outputting it. CONSTITUTION:In the case of depending on frequency shift type modulation, the voltage level of a power supply battery 5 is compared with a threshold value by a voltage monitor 6. When the power supply voltage level is lower than the threshold value, the output of the voltage monitor 6 is turned to '0' and since a switch 8 is changed over, the oscillation frequency of an AC signal generator 7 is lowered. A signal outputted from a signal transmission part 9 is inputted to the tablet and impressed to a frequency counter as the decoder of the signal processing part. Corresponding to this frequency counter value, a control part recognizes the state of lowering the power supply voltage of the input pen and digitally outputs it together with coordinate information.</p> |
