| 摘要 |
PURPOSE:To enable a range finding with smaller ripple and higher accurcy by changing in steps the time constant of a smoothing circuit smoothing the output of a detection circuit. CONSTITUTION:When a current I1 flows to the transistor (TR)37 of a current mirror circuit from a constant current power source 35. The current I1flows to the collector of a TR38 as well due to a mirror effect. The composite current I1+I2+I3 of the currents I1, I2, I3 of the constant current source becomes to flow to a TR39 by setting similar circuit to a block 32 on circuits 31, 30. Since the TRs 39, 40 and TRs 41, 42 are respectively made in current mirror, the current equivalent to the composite current of TR39 flows to the collector TR40 and further flows to TR41 as well. The composite current I1+I2+I3 flows to the collector of TR42 as well. By changing the controlling signal for terminals 29-27 in order to L H level, it is enabled to change the collector current of TR42 to I1+I2+I3 I2+I3 I3 0, and to change variously the characteristics of smoothing circuit with changing the output current of a time constant variable circuit. |
