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Browse Prior Art Database

Opto-electrical Scanning System For Gray Level Detection

IP.com Disclosure Number: IPCOM000095438D
Original Publication Date: 1964-Jan-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Jensen, HH: AUTHOR [+2]

Abstract

The scanning system is for transducing analog information codified as varying levels of light transmissivity into electrical signals convertible to digital form. The analog information is contained on transparency 1 in a form of areas of different light transmissivity such as a photographic transparency. Graduated standard scale 2 of known light transmissivity is previously, selectively scanned at a certain level of light transmissivity by the flying spot of cathode ray tube (CRT) 3.

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Opto-electrical Scanning System For Gray Level Detection

The scanning system is for transducing analog information codified as varying levels of light transmissivity into electrical signals convertible to digital form. The analog information is contained on transparency 1 in a form of areas of different light transmissivity such as a photographic transparency. Graduated standard scale 2 of known light transmissivity is previously, selectively scanned at a certain level of light transmissivity by the flying spot of cathode ray tube (CRT) 3.

The light beam is fed to a photomultiplier tube (PMT) 4, producing an electric signal of discrete amplitude which is stored in a condenser storage 5. Switch 6 is closed and switch 7 is open. Transparency 1 is now scanned. The light beam produces electric signals of different levels at the output of PMT 4. These are fed to a first input of differential amplifier 8.

The voltage previously stored in storage 5 is applied to the second input of amplifier 8. This is such that an output signal 1 is present only when the light beam passes through an area of light transmissivity lower or equal to that in scale 2. The output signal in digital form is fed to a central processing unit (CPU) 9 and then to an utilization apparatus.

A feedback regulating circuit 10 holds the intensity of light beam from CRT 3 constant. CPU 9 drives the deflection electrodes of CRT3 for scanning transparency 1 and scale 2.

By providing a sufficient number of s...