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Browse Prior Art Database

Automatically Checked Photoelectric Apparatus

IP.com Disclosure Number: IPCOM000085608D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Schaaf, RL: AUTHOR

Abstract

A photoelectric apparatus includes a light-emitting diode (LED)array supplying light through a mask to a receiving photodiode array. Relative movement of the mask to the arrays is indicated by the signal patterns supplied by the photodiode array through a multiplexer circuit to a utilization device. The utilization device may be a servomechanism for relatively moving two members respectively mounting the mask and the arrays.

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Automatically Checked Photoelectric Apparatus

A photoelectric apparatus includes a light-emitting diode (LED)array supplying light through a mask to a receiving photodiode array. Relative movement of the mask to the arrays is indicated by the signal patterns supplied by the photodiode array through a multiplexer circuit to a utilization device. The utilization device may be a servomechanism for relatively moving two members respectively mounting the mask and the arrays.

In accordance with this method, the address-in not only selects the LED array pattern, but also constitutes a test pattern for verifying proper operation of the arrays. The address-in is stored in the register which, in turn, increments and resets a scan counter for scanning the LED array. The output of the scan counter is multiplexed back to a test and compare circuit, wherein predetermined relations between the address-in and the output of the scan counter are verified. Further, the signals from the photodiode array resulting from the address test pattern, are multiplexed to the test and compare circuits for a further verification.

Using the known patterns enables circuit fault pointing and verifies drive sequences from the LED array.

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