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Safety Shutter for Laser Scanner

IP.com Disclosure Number: IPCOM000085702D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Bratvold, DE: AUTHOR [+2]

Abstract

Safety precautions are required when a laser scanner is used in a publicly accessible environment, such as a supermarket. The most important safety measures are to control the amount of exposure to the laser beam and to prevent exposure to the beam when it is not being moved by its deflection system. The safety mechanism itself must also be fail-safe.

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Safety Shutter for Laser Scanner

Safety precautions are required when a laser scanner is used in a publicly accessible environment, such as a supermarket. The most important safety measures are to control the amount of exposure to the laser beam and to prevent exposure to the beam when it is not being moved by its deflection system. The safety mechanism itself must also be fail-safe.

Fig. 1 shows the electromechanical portion of a safety shutter, in simplified form. Laser 10 emits light beam 11, which is swept through a scan pattern by oscillating mirrors in deflection unit 12. An item senser includes light-emitting diode 13 for producing beam 14, which is sensed by photodetector 15. An ITEM signal is produced whenever an object to be scanned breaks beam 14 as it passes through the area of the scanned beam 11. Laser power supply 17 is controlled by a power-down laser signal PDL.

Solenoid 19 controls a shutter arm 20 having a triangular cross section. Arm 20, shown in its open position in Fig. 1, has a reflective angled surface 21. When power on line SOL is removed, arm 20 falls to intercept beam 11, so that surface 21 reflects beam 11 to photodetector 23, producing a signal DET. Vertical and horizontal deflection good signals VDC, HDC are active when the deflection system is operating properly. Detectors 26 provide signals FIP and WC when a scan-window filter is in place and when the window is closed.

Fig. 2 shows a logic circuit for disabling the scanner by cont...