| 摘要 |
PURPOSE:To enable the detection of coordinates with high accuracy, by a method wherein a voltage control oscillator is used as a rectangular wave oscillator and the output thereof is inputted to a count circuit while the content successively read from ROM using the count output of said circuit as an address is obtained as a stepwise dummy sine wave by a DA converter to be used as a phase comparing signal. CONSTITUTION:A capacity detection apparatus is constituted so that a voltage control oscillator 41 is used as a rectangular wave oscillator and rectangular wave output is counted by a count circuit 51 and the value of a sine wave successively encoded is read from ROM52 using the output of said circuit 51 as an address is converted by a DA converter 53 to output a stepwise sine wave. Therefore, the strain in a low frequency region is extremely small and used as phase comparing reference to make it possible to detect coordinates with high accuracy.
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