| 摘要 |
<p>PURPOSE:To enable swiftly and highly precisely an inspection of focus without requring a mechanism part such as a sensor moving table, by a method wherein pitches among dots each of a line sensor and LED head are made to differ from one another and a moire interference pattern is obtained on a light volume signal measured by the line sensor. CONSTITUTION:Since output signals of a line sensor 4 are read out electrically in order of dot number by a sensor signal treatment part 5, a signal pattern is put out as time sequence signal. Hereupon, since a pitch between dots of an LED head 1 and that of the line sensor 4 are different slightly from each other, the more a dot signal advances, the more a confronting relation between an LED dot of the LED head 1 and a detector dot of the line sensor 4 changes little by little and light volume inciding into detectors each of the line sensor 4 is changed little by little. Therefore, a light volume signal to be measured by the detectors each of the line sensor becomes a moirelike pattern. Therefore, the maximum value I max and minimum value I min of the moire pattern are obtained, through which an extent of coincidence of the focuses can be obtained quantitatively.</p> |
