| 摘要 |
PURPOSE:To perform automatic focal matching, by sampling a signal of a definite period containing no horizontal synchronous signal from the horizontal scanning signal of an image signal to compare the same with reference voltage and setting a focus to the position corresponding to the number of the max. pulses of comparing output. CONSTITUTION:A microscope 1 and a television camera 2 are supported in a freely rising and falling state by an apparatus main body 8 and a z-axis direction moving motor 9 driving the microscope 1 up and down is controlled by a control circuit 10. A sampling circuit 3 samples a signal of a definite period containing no horizontal synchronous signal from the arbitrary scanning signal of an image signal. A signal conditioner 22 cuts a low frequency component from the signal sampled and the output signal thereof is compared with reference voltage by a voltage comparing circuit 4. The number of the output pulses of the voltage comparing circuit 4 are counted by a pulse count circuit 5 and the number of the pulses counted are compared with the previous value by a number-of-pulse comparing circuit 6. A focus position moving control apparatus 7 repeats procedure while successively changes a focus position in a direction increased in the number of pulses and allows a focus to move to the position corresponding to the number of the max. pulses and, on the basis of the output of said control circuit 7, the distance between an objective lens 13 and an article 11 to be measured is controlled through a motor 9. |
