Importance

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Abstract

A speed measuring apparatus and a toy for measuring a speed of a moving member has a quartz oscillator for generating a clock signal which has a predetermined frequency, a CR oscillator for generating a clock signal which has a higher frequency than that of the quartz oscillator, a comparative circuit, connected with the quart oscillator and the CR oscillator, for comparing the oscillation frequency of the quartz oscillator as a reference signal with the oscillation frequency of the CR oscillator, a corrective circuit, connected with the comparative circuit, for calculating a corrective factor in accordance with a result from the comparative circuit, a measuring unit, connected with the CR oscillator and the corrective circuit, for measuring a speed of the moving member in accordance with the clock signal from the CR oscillator and the corrective factor from the corrective circuit, and a display unit, connected with the measuring unit, for displaying the speed computed by the measuring unit. Therefore, in the speed measuring apparatus and the toy, the speed can be measured correctly with an increased number of significant figures, and the increase of the cost is suppressed, even if the oscillation frequency of the CR oscillator is fluctuated by the fluctuations of the temperature and the humidity, because the clock signal from the CR oscillator is corrected in accordance with the clock signal from the quartz oscillator.

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First Claim