Browse Prior Art Database

Automatically Checked Photoelectric Sensing Apparatus

IP.com Disclosure Number: IPCOM000085419D
Original Publication Date: 1976-Apr-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Schaaf, RL: AUTHOR

Abstract

In a photoelectric sensing array characterized by a light-emitting diode (LED) array and a photodiode array for sensing the emitted light from the LED's, respectively, malfunctions should be promptly detected and located.

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Automatically Checked Photoelectric Sensing Apparatus

In a photoelectric sensing array characterized by a light-emitting diode (LED) array and a photodiode array for sensing the emitted light from the LED's, respectively, malfunctions should be promptly detected and located.

This is achieved by ensuring that each symbol area, represented by ' the parallel lines, on the indicia member has a transparent area for transmitting light from at least one LED to at least one photodiode. This is simply achieved by Gray coding the indicia member, with the Gray code binary 1's being represented by transparent areas and binary 0's by the hatched-indicated opaque areas.

Using the above-described indicia member during each symbol area sensing, at least one of the photodiodes will be illuminated to indicate operability of a portion of the photoelectric apparatus. To ensure that no photodiode is falsely emitting binary 1 signals, a dark test initiated by opening the switch labeled "Dark Test" enables checking for spurious 1-indicating signals.

In one embodiment, the LED array and the photodiode array are mounted on a carriage, not shown, movable past the indicia member for indicating the relative position of two relatively movable members. The scanner scans the photodiode array for each symbol area and supplies the scanned signals through an amplifier over a single communication line to a deserializer. The deserializer, in turn, supplies the deserialized symbol indicating signals...