| 摘要 |
PURPOSE:To enable positioning of plate bodies to be easily carried out with high accuracy by comparing the output timings of the wave forms of a transmitted- light detection output and a reflected-light detection output which are obtained by sweeping a laser beam spot on each pattern of the plate body. CONSTITUTION:In the vertical portion of each T-shaped mark pattern 30, for instance, four sets of stripes 12R, 12B and 12G constituting the vertical portion of a pattern 31 are formed, and for example seven Nesaless lines 24 constituting the vertical portion of a pattern 32 are formed corresponding to the stripes. On each of the T-shaped patterns 30a and 30b, a red laser beam spot is formed which is swept at the same phase and an equal amplitude. Seven pulses corresponding to the seven Nesaless lines 24 appear in detection outputs NA and NB delivered from a reflected-light detector, while four pulses corresponding to the four R stripes appear in detection outputs FA and FB delivered from a transmitted-light detector. The positional relationship between the patterns can be known by comparing the timings of the pulse lines. |
