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Selective Field Reading for Optical Character Reader

IP.com Disclosure Number: IPCOM000094146D
Original Publication Date: 1966-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 4 page(s) / 66K

Publishing Venue

IBM

Related People

Dohler, DE: AUTHOR [+2]

Abstract

In character recognition systems it is sometimes desired to have the system selectively ignore information which is otherwise entered by the system as a result of the scanning of a document. For example, it can be desired to eliminate certain groups of characters in particular locations on a series of documents. Selective field reading can be obtained in an optical character reader employing a cathode ray tube flying spot scanner by this system.

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Selective Field Reading for Optical Character Reader

In character recognition systems it is sometimes desired to have the system selectively ignore information which is otherwise entered by the system as a result of the scanning of a document. For example, it can be desired to eliminate certain groups of characters in particular locations on a series of documents. Selective field reading can be obtained in an optical character reader employing a cathode ray tube flying spot scanner by this system.

Two types of blanking can be provided. In drawing 1, center blanking of a group of characters is shown in which the digits 7, 8, 9, 0, extending between format A and format B pips, are not supplied to the associated data processing system. This is because the character recognition system is governed to ignore any information in the scanning of the document between the A and the B pips. In the end blanking mode shown in drawing 2, the system ignores information except that which is present between format B and format A pips.

Generally, the system operates by providing a series of variable voltages selected by the operator which are proportional to desired scanning or field limits. The apparatus compares the deflection voltage of the cathode ray tube scanner, which is also proportional to the position of the scanning beam, the limits set up by the operation. The resulting information is utilized to gate the video or scanning signals so that they are supplied to the analyzing portion of the system. Such occurs only during the intervals in which it is desired to read information from the document. This system also contemplates the display of information on a suitable display oscilloscope so that the operator can check the adjustment of the scanning limits. A further feature in this arrangement is the provision of devices which automatically check the reading limit adjustment and halts the operation of the system and causes a display to be provided to the operator. Thus the limits can be readjusted to provide proper operation. One arrangement of the circuitry is shown in drawing 3. A plurality of voltage discriminators indicates with a digital output which of two input voltages supplied them is more positive. The input designated HD is the voltage which is proportional to the horizontal position of the scanning spot and is supplied to one of the two inputs of the first four voltage discriminators. The other inputs are A1 and A2 associated with the A pip and B1 and B2 associated with the B pip, and are adjustable voltages set by the operator.

Adjustable voltage dividers 6 and 7 are set by the operator to obtain output voltages corresponding to the desired reading limits. Limits A1 and B1 are a direct result of the voltage divider setting. A2 and B2 are offset from A1 and B1, respectively, by a fixed amount established by the resistor divider chain associated with voltage dividers 6 and 7. Thus the outputs of the voltage discriminators indicate...