In the proofreading manner which is proofread in the vicinity of the impression timing which control means of the strobed pulse which consecutively supplies the time delay

摘要

PROBLEM TO BE SOLVED: To perform calibrating operation to calibrate the delay time of a pattern signal in a short time. SOLUTION: A phase correcting circuit 10 is provided with a counter 15. A clock to be outputted at every test cycle is inputted to the counter 15 to increase the enumerated value of the counter 15 at every test cycle by +1. The delay time of the phase correcting circuit 10 is sequentially increased by a predetermined time to sequentially delay the phase of a pattern signal which passes through the phase correcting circuit 10. Then that the rise timing of the pattern signal becomes delayed in phase more than the application timing of a strobe pulse is detected by the inversion of the output of a signal reading means 14. The gate supplying a clock for the counter 15 is closed, and the enumerating operation of the counter 15 is halted to complete calibration.