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Optical Sensor for Removing Interference due to Dye Based Inks

IP.com Disclosure Number: IPCOM000076138D
Original Publication Date: 1972-Jan-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Baxter, DW: AUTHOR [+3]

Abstract

An optical scanner responsive to light in the visible spectrum is ineffective for the recognition of characters printed over a low-contrast pattern background.

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Optical Sensor for Removing Interference due to Dye Based Inks

An optical scanner responsive to light in the visible spectrum is ineffective for the recognition of characters printed over a low-contrast pattern background.

Such background patterns are generally printed in a dye-base ink and, therefore, are invisible to a scanner operating in the infrared spectrum. There are occasions where the character to be recognized is printed in a dye-base ink so a complete change to infrared scanning is not acceptable.

In the System shown, the light reflected from the document passes through a filter 1 before sensing by array 2. Without any filtering, optical sense array 2 would have a response as indicated in Fig. 2.

When filter 1 is in the position shown, the light reaching array 2 passes through filter portion 3, which blocks light having a wavelength greater than 700 nanometers. Array 2 is therefore operative to scan only in the visible spectrum.

Where logic circuits 4 indicate that background is being picked up, an output signal is transmitted to solenoid driver circuits 5. This causes solenoid 6 to move filter 1 in the direction of the arrows and interpose portion 7. Since the filter portion 7 blocks the transmission of light in the visible spectrum, that is, light having a wavelength shorter than 700 nanometers, scanning occurs only in the infrared spectrum.

Photodetector array 8 has a low resolution and operates in the infrared spectrum. If array 8 detects black vid...