| 摘要 |
<p>PURPOSE:To improve READ efficiency and to protect human eyes from injuries by a method wherein a means is provided for preventing the product, which is the maximum laser output times the length of time wherein the output continues, from exceeding a certain prescribed value. CONSTITUTION:A mechanical shutter 5 shuts off the output of laser. A laser beam is projected by a scanner 6 against the reading surface 8 of a laser scan platform 7 only when a bar code is to be read. Optical detectors 91, 9'1 and 92, 9'2 are provided for sensing if there is a commercial article in place, and the signals they output are detected by a switch section 12, for the control of the mechanical shutter 5 with the intermediary of a control section 1. To prevent human eyes from hazards that may arise when the commercial article remains in place for a prolonged period of time, a timer 10 goes into operation and the laser projecting time length is set in a time set section 11, upon detec tion by the optical detector 91 or 92 of the presence of the commercial ariticle, with the length of time determined in view of the maximum output power of a He.Ne laser tube 2. The mechanical shutter 5 is forced to go into operation when the time limit is reached.</p> |
