Browse Prior Art Database

Linear Angle Encoder

IP.com Disclosure Number: IPCOM000079186D
Original Publication Date: 1973-May-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Burke, MJ: AUTHOR [+2]

Abstract

This system measures the angular position of a folding mirror used in an optical character recognition (OCR) system. The encoder output positions the mirror accurately over a line of printed information. The hardware used in conjunction with this self-correcting system is described in the IBM Technical Disclosure Bulletin, Volume 15, No. 1, June 1972, pages 59 and 60.

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Linear Angle Encoder

This system measures the angular position of a folding mirror used in an optical character recognition (OCR) system. The encoder output positions the mirror accurately over a line of printed information. The hardware used in conjunction with this self-correcting system is described in the IBM Technical Disclosure Bulletin, Volume 15, No. 1, June 1972, pages 59 and 60.

A photocell PC1 produces a voltage proportional to the amount of light striking its surface. This voltage is amplified by amplifiers 1 and 2 to provide a usable position signal to VO2. Provisions are made in this system to calibrate offset and gain, which compensates for variations due to component drift and temperature.

Offset Calibration: The light-emitting diode (LED) 1, which energizes photocell PC1, is turned off, reducing the input voltage to amplifier (AMP) 1 to zero volts. This is equivalent to moving the mirror to an angular position selected during the initial mechanical setup adjustment. Since this position is mechanically fixed, the output of AMP 2 can be adjusted to a known voltage with one point on the angle-to-voltage curve accurately defined. This adjustment is made bv electronically closing switch SW1, which charges capacitor C1 with the output of AMP 3 until the output of AMP 2 is equal to the accurate referenced voltage V(ref).

Gain Calibration: Gain is calibrated by adjusting LED 1 current and thereby its light output, until the output voltage of AMP 2 agrees...