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Sense Level Adjustment Device for Image Scanning Machine

IP.com Disclosure Number: IPCOM000044007D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Kobayashi, Y: AUTHOR

Abstract

To enable an operator of an image scanning machine to easily adjust a sense level of the machine without a test chart, a device is provided for rapidly and accurately obtaining an average voltage of white level of the sensed image signals regardless of the degree of coarseness of the form surface being scanned. In Fig. 1, an image sensor 1 for optically scanning a form 2 generates outputs as voltage signals through an pre-amplifier 3. Depending on the intensity of the light from the form surface, the voltage signals vary in amplitude with respect to the black reference level. Also, as shown in Fig. 2, the signals at the white level are slightly varied depending on the reflectance of the form surface.

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Sense Level Adjustment Device for Image Scanning Machine

To enable an operator of an image scanning machine to easily adjust a sense level of the machine without a test chart, a device is provided for rapidly and accurately obtaining an average voltage of white level of the sensed image signals regardless of the degree of coarseness of the form surface being scanned. In Fig. 1, an image sensor 1 for optically scanning a form 2 generates outputs as voltage signals through an pre-amplifier 3. Depending on the intensity of the light from the form surface, the voltage signals vary in amplitude with respect to the black reference level. Also, as shown in Fig. 2, the signals at the white level are slightly varied depending on the reflectance of the form surface. The highest voltage of the image sensor's output signals is retained in a peak- hold circuit 4, so that the voltage at point A is always highest in the white level. The output of the peak-hold circuit 4 at point B is compared with the image sensor output at the white level by a comparator 5, which provides a blank signal when the voltage at point A is higher than that of the image sensor output. Each of the blank signals is counted by a counter 6 which can provide the percentage of the blank signals in a predetermined period to energize one of the LEDs (light- emitting diodes) corresponding to the percentage. For adjusting the sense level of the scanning machine, a white form is scanned by the image sensor 1 an...