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Overcoming Spot Delay In a Cathode Ray Tube

IP.com Disclosure Number: IPCOM000098878D
Original Publication Date: 1958-Aug-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Brown, CJ: AUTHOR [+2]

Abstract

In a flying spot cathode ray tube scanning device in which it is desired to position the spot at the point at which recorded indicia is encountered, the spot overshoots this point when a magnetic deflection CRT is used. The inductance of the yoke causes the spot to lag the deflection voltage. When the sweep is terminated under control of the sensed indicia, the deflection of the spot continues until its position corresponds to the deflection voltage.

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Overcoming Spot Delay In a Cathode Ray Tube

In a flying spot cathode ray tube scanning device in which it is desired to position the spot at the point at which recorded indicia is encountered, the spot overshoots this point when a magnetic deflection CRT is used. The inductance of the yoke causes the spot to lag the deflection voltage. When the sweep is terminated under control of the sensed indicia, the deflection of the spot continues until its position corresponds to the deflection voltage.

The circuit provides a correction to the sweep voltage so that the spot is positioned at the point at which it encounters the recorded indicia. The sweep is initiated by a signal applied to a line 10 which connects to the vertical sweep circuit 11 and is terminated when a Schmitt trigger 12 is operated. When the spot of the cathode ray tube encounters the recorded indicia a signal is entered on a line 13 for operating the trigger 12 to terminate the sweep. In addition to terminating the sweep, operation of the Schmitt trigger 12 is arranged to operate a trigger 14 for entering the correction voltage on a line 15. The line 15 and a line 16, from which the vertical sweep voltage is taken, connect through suitable voltage adding resistors 17 and 18 to the vertical sweep voltage line for controlling vertical deflection of the cathode ray tube spot. The voltage provided by the trigger 14 to the line 19 is of sufficient magnitude to compensate for the overshoot caused by the indu...