| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a measurement device that has simple and compact constitution with small restriction in terms of constitution and usage by using a surface acoustic wave excited in a base to detect position information on the base. <P>SOLUTION: The measurement device 100 has exciters 102, 103 composed of IDTs as a pair of interdigital electrodes and a receiver 105 on a scale substrate 101 made of a glass ceramic material that can propagates a surface acoustic wave and has an extremely small coefficient of thermal expansion. The exciters 102, 103 excite a standing wave of a surface acoustic wave in the scale substrate 101. The receiver 105 detects the surface acoustic wave and outputs an elastic wave detection signal while displaced on the scale substrate 101. The elastic wave detection signal outputted from the receiver 105 is inputted to a displacement amount calculation portion 114 through a tuning circuit 112 and a low-pass filter 113. The displacement amount calculation portion 114, after converting the elastic wave detection signal into a pulse signal corresponding to the amplitude, calculates a displacement amount corresponding to the number of pulses of the pulse signal. <P>COPYRIGHT: (C)2012,JPO&INPIT |
