| 摘要 |
PURPOSE:To obtain a sweeping speed at any time, by running an output current of a control current source to a capacitor composing a sweeping circuit to charge so that the output current value thereof is made programmable while the output current value is measured. CONSTITUTION:When an increment/decrement counter 14 is set to a maximum possible set value under the calibration of the sweeping speed, the maximum of a current (i) and a current i2 flows through a D/A converter 16 as reference current. Under such a condition, when the set data of the sweeping speed is altered, an output current i1 of the converter 16 varies with the alteration thereof. As this current i1 charges a capacitor 2, the gradient of a saw tooth wave of a sweeping output is changed to accomplish a switching of the sweeping speed. Then, when a clock pulse is applied to the counter 14, the output current i2 of a converter 15 changes corresponding to a count value of the counter 14. Now when the maximum of the current i2 is set smaller than the current (i), the counter 14 is decremented to make the sweeping speed variable within the speed corresponding to a set sweeping speed data for the converter 16. Thus, the measuring of the altered value of the sweeping speed can be done with the counter 14.
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