Browse Prior Art Database

CRT Device Used for Graphical Digital Input

IP.com Disclosure Number: IPCOM000095106D
Original Publication Date: 1965-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Grace, HR: AUTHOR

Abstract

This CRT display unit for the output from a digital computer also provides input data to the computer. The system operates upon receipt of a start signal, for example, from a manual switch on photosensor 11. Control circuitry 10 switches CRT display deflection input 12 from its D-to-A converter output register 18 to the output of sweep generator 16 through switch 20. Circuitry 10 also connects sweep generator 16 as a stepping input to register 22 through switch 24. Register 22 functions as a binary counter for this operation, driving deflection input 14 through switch 26.

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CRT Device Used for Graphical Digital Input

This CRT display unit for the output from a digital computer also provides input data to the computer. The system operates upon receipt of a start signal, for example, from a manual switch on photosensor 11. Control circuitry 10 switches CRT display deflection input 12 from its D-to-A converter output register 18 to the output of sweep generator 16 through switch 20. Circuitry 10 also connects sweep generator 16 as a stepping input to register 22 through switch
24. Register 22 functions as a binary counter for this operation, driving deflection input 14 through switch 26.

Sweep 16 then sweeps the face of the CRT in one direction, while stepping in the other direction, until the sweep is detected by photosensor 11. At this time, circuitry 10 switches input 12 back to register 18, switches input 14 from register 22 to sweep 16, and switches the latter to register 18. The sweep and step operations then repeat until the sweep is again detected by photosensor 11. At this time, the operation is complete and the scan is terminated. Registers 18 and 22 contain X and Y coordinates corresponding to the position of photosensor 11 on the face of the CRT.

Photosensor 11 detects a rapid shift in intensity, rather than any fixed intensity level. This permits the use of a self-storing CRT. Holding the sweep intensity below the intensity required to cause storage on the CRT face permits the scanning operation to occur without affecting...