Browse Prior Art Database

Item-Sensing Technique for a Supermarket Scanner

IP.com Disclosure Number: IPCOM000044288D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Broockman, EC: AUTHOR [+5]

Abstract

Supermarket scanners commonly use protruding item sensor rails on opposite sides of an item approach path. The rails include a light source/ detector arrangement. This article describes a technique for achieving item sensing without the use of rails. A high brightness LED (light- emitting diode) in the scanner serves as a source of item-sensing light. The LED remains on continuously. When an item is sensed, a laser scanning beam is allowed to exit the scanner. Fig. 1 shows the essential elements of a scanner of the type including a rotating holographic disk 10 as a beam-deflecting element. The disk 10 is located below a top surface 12 having a transparent scan window 14. The scanner includes a laser 16 with an electromechanical shutter mechanism 18.

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Item-Sensing Technique for a Supermarket Scanner

Supermarket scanners commonly use protruding item sensor rails on opposite sides of an item approach path. The rails include a light source/ detector arrangement. This article describes a technique for achieving item sensing without the use of rails. A high brightness LED (light- emitting diode) in the scanner serves as a source of item-sensing light. The LED remains on continuously. When an item is sensed, a laser scanning beam is allowed to exit the scanner. Fig. 1 shows the essential elements of a scanner of the type including a rotating holographic disk 10 as a beam-deflecting element. The disk 10 is located below a top surface 12 having a transparent scan window 14. The scanner includes a laser 16 with an electromechanical shutter mechanism 18. The scanner includes a photodetector 20 which provides an output to a microprocessor 22 under the control of either a conventional gain circuit 24 or a high Q gain circuit 26. The scanner also has a high brightness red LED 28, a collimating lens 30 and an oscillator/control circuit 32 for modulating the light produced by LED 28. In a detect mode, the shutter 18 is closed. Light produced by LED 28 passes through a small opening in a mirror 34 and is deflected by the holographic disk 10. The LED light has a center wavelength very close to the wavelength of light generated by a helium-neon laser. Therefore, the LED light beam is deflected along generally the same scan lines as the laser light and operates a very similar scan pattern. The major difference is that the scanning "spot" of the LED beam is much larger than that of the laser beam due to the greater bandwidth of the LED light and the characteristic dispersion of the holographic disk. The LED light is reflected b...