HIGH-SPEED MTF MEASURING APPARATUS FOR LED ARRAY

摘要

PURPOSE:To omit a wave-form observing means by providing an MTF control circuit for logically processing measurement timing control and defective dot detection following the moving speed of a slit, and providing an MTF-period detecting circuit. CONSTITUTION:An MTF control circuit 53 receives a starting signal and a period abnormality signal from an MTF-period detecting circuit 55 and controls the holding timings of an MAX holding circuit 51 and an MIN holding circuit 52. The circuit 53 logically supplies MTF sample signals into a sample holding circuit 57 when the MAX of the wave form is held in the MAX holding circuit 51 and MIN of the wave form is held in the MIN holding circuit 52, and when the MAX of the next wave form is not detected even if the time corresponding to the MTF period determined by the moving speed of a moving table 2 is elapsed from the time when the MAX of the wave form is once detected. The operated MTF output from an analog operating circuit 56 is sampled and held.