Browse Prior Art Database

Optical Density Quantizer

IP.com Disclosure Number: IPCOM000096244D
Original Publication Date: 1963-Feb-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Simpson, BE: AUTHOR

Abstract

This circuitry is for correcting for variations in CRT brightness in an optical scanning apparatus which line scans images for electronic transmission of photographs.

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Optical Density Quantizer

This circuitry is for correcting for variations in CRT brightness in an optical scanning apparatus which line scans images for electronic transmission of photographs.

The flying spot output from scanner cathode ray tube 1 is transmitted via optical system 2 to a photopickup device 3. This is a monitor light sensor and provides an output on line 4 proportional to the spot of light. The light spot is also read by light sensor 5 through photographic transparency 6 to provide a film modulated output on line 7. The direct output from sensor 3 after amplification by amplifier 8 is applied by way of line 9 to the analog input of a digital-analog multiplier 10. Here the analog value is adjusted by the binary value of the digital threshold signal from a computer.

The output from multiplier 10 on line 11 is then compared with the film modulated signal on line 7 through difference amplifier 12 and null detector- comparator 13. The output signal on lines 14 and 15 indicates the light level measurement. This is relatively independent of the intensity of the CRT spot.

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