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Technique to Set Light Uniformity on a Copy Easel

IP.com Disclosure Number: IPCOM000094951D
Original Publication Date: 1965-Jul-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Johnson, JI: AUTHOR [+2]

Abstract

In a microfilming operation, each time the size of material to be copied changes, the copy camera lights must be readjusted to compensate for the change of magnification and the size of the copy field. Ordinarily, light adjustments are made with a blank easel. Trial exposures are then made resulting in lost time and wasted materials in order to arrive at proper illumination of the copy.

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Technique to Set Light Uniformity on a Copy Easel

In a microfilming operation, each time the size of material to be copied changes, the copy camera lights must be readjusted to compensate for the change of magnification and the size of the copy field. Ordinarily, light adjustments are made with a blank easel. Trial exposures are then made resulting in lost time and wasted materials in order to arrive at proper illumination of the copy.

A CRT display is used to indicate to the operator what areas require lighting modification and also show the results of adjustments as they are made. The copy camera film back is temporarily replaced by a scanner or image disector. This produces an electrical output modulated according to the illumination received at scanned points of the camera focal plane.

The DC component of the signal is removed. The AC component is applied to the Z input of the CRT. This then displays an intensity-modulated pattern representative of the illumination pattern of the easel copy area. Lamp adjustments are made to cause the raster pattern to become uniform. After this, the scanner or disector is replaced with the camera film holder until a different size of copy is to be photographed.

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