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Automated Print Band Encoder Slot Spacing Inspection Device

IP.com Disclosure Number: IPCOM000038178D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Logan, TD: AUTHOR

Abstract

Disclosed is a device to automate a low cost high speed inspection of equally spaced print band slot locations with high accuracy. The device rotates the band around two rotors while an optical sensor measures the slot to slot timing.

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This is the abbreviated version, containing approximately 69% of the total text.

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Automated Print Band Encoder Slot Spacing Inspection Device

Disclosed is a device to automate a low cost high speed inspection of equally spaced print band slot locations with high accuracy. The device rotates the band around two rotors while an optical sensor measures the slot to slot timing.

The present embodiment is designed for inspection of a print band
48.000000 +/- 0.002" long with 576 encoder slots, and slot to slot spacing of
0.083333 +/- 0.0005". From this it is seen that the average slot spacing is
48.00/576 = 0.83333" and the worst case average spacing is 48.002/576 =
0.0833368". Thus, the average nominal slot spacing is .083333" with a possible error of of .0833369 - .0833333 = 3.5 X 10-6.

This device consists of two rotors which are of high mass, to minimize the effects of speed variations, and are precisely machined and fitted to their shafts to minimize eccentricity. In addition, for the present embodiment, the drive rotor diameter is such that it phase shifts 1/10th of a revolution for each full pass of the print band.

The print band passes around the rotors at approximately 200 inches/second. (The actual speed is not critical as long as it is constant while data is being taken.) All the slot timing data is taken, by the optical encoder, on ten consecutive passes of the print band. The data for the ten readings for each slot is then averaged, thus further reducing the effect on speed by any tester eccentricity. This results in a table of 576 valu...