| 摘要 |
PROBLEM TO BE SOLVED: To accurately grasp the position and number is substrates by attaching a reflector to an inside or an outside of a rear of a substrate container for detecting the number of substrates from one direction and detecting whether or not optical beam is screened by a substrate by reflecting optical beam cast from a projection means of a reflector. SOLUTION: Laser beam is screened by a substrates 2 by moving a hand part 6 up and down by an elevator 10 and in a place whether the substrate 2 does not exist, it is reflected by a corner cube mirror 3 and injected to a photosensor 14. When there is an obstacle on an optical path of a laser, laser beam is scattered, thus reducing a light amount injected to the photosensor 14. Thereby, output of the sensor 14 lowers and shows the presence of the substrate 2 on an optical path. According to this constitution, it is possible to detect the presence or absence of a substrate 2 by observing output of the sensor 14. If the substrate 2 exists on an optical path, output of the photosensor 14 becomes an 'L$ level and if the substrate 2 does not exist, the photosensor 14 is in a fixed level 'H' and shows the presence of the substrate 2. |
