Browse Prior Art Database

CRT Display With Pen Tracking

IP.com Disclosure Number: IPCOM000097229D
Original Publication Date: 1962-Jul-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 3 page(s) / 73K

Publishing Venue

IBM

Related People

Randa, GC: AUTHOR

Abstract

The system effects drawing or erasing lines on the face of a display device and inserting data into a memory device. Light pen 10 is positioned in front of CRT 11 and observes the spot on its face. By moving pen 10, lines are drawn on or erased from the CRT face and corresponding data is stored.

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CRT Display With Pen Tracking

The system effects drawing or erasing lines on the face of a display device and inserting data into a memory device. Light pen 10 is positioned in front of CRT 11 and observes the spot on its face. By moving pen 10, lines are drawn on or erased from the CRT face and corresponding data is stored.

In a pen tracking operation, the initial center position of the field of view of pen 10 is known. The pen track signal is at the positive level. During the first word time, timing signal WG1, the initial center coordinates of the field of view of pen 10 are introduced into one word revolver 12 via And 13. At the beginning of the second word time, WG2, the initial center coordinates are gated to decoding matrix 14 and pass to the X and Y deflection counters 15 and 16. Counters 15 and 16 and associated deflection circuitry assimilate and respond to the initial center coordinates during the third and fourth word times. The spot on the CRT face is now positioned at the initial center of the field of view of pen 10. It is necessary to determine the new center coordinates of the field of view.

At the beginning of the fifth word time, WG5, flip-flop 17 is set. The counter 15 up input is energized by the Or 18 output. Pulses from source 19 advance counter 15. This occurs until the spot on the CRT face moves out of the field of view of pen 10. The pen 10 signal drops to zero and the inverter 20 output resets flip-flop 17 to stop counting.

During the sixth word time, WG6, the counter 15 down input is energized by the And 21 output. Flip-flop 17 is again set and counter 15 is counted down until the CRT spot advances in the opposite direction beyond the field of view of pen
10. The counting pulses also pass to auxiliary counter 22 via And 23 and Or 24. At bit-gate nine, BG9, of the sixth word time, the counter 22 contents are shifted by one bit, the same as dividing by two. Counter 15 now contains the location of one edge of the field of view of pen 10. Counter 22 con...