US 4,305,022 AGranted

Horizontal scanning rate correction apparatus

AssigneeSony Corporation

InventorsIchiro Mitamura, Katsuo Isono

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Abstract

A horizontal scanning rate correction apparatus for a cathode-ray tube, particularly of the beam index color cathode-ray tube type, includes a memory for storing correction values representing deviations of the horizontal scanning rate of the electron beam from a desired scanning rate at each of a plurality of horizontal sampling positions along each of a plurality of predetermined horizontal sampling lines which are substantially fewer in number than the horizontal lines along which scanning occurs. During display of a video signal, a selected one of the stored correction values is read out of the memory for each scanning position of the beam along a scanned one of the horizontal lines, with each read correction value, and a corresponding sampling line correction signal produced therefrom, representing the deviation at a corresponding horizontal sampling position on one of the sampling lines. A scanned line correction signal is then produced for each horizontal scanning position which is a function of the sampling line correction signal and of the vertical position of the respective scanned line, and the scanned line correction signal is applied to the beam deflection yoke or device to substantially cancel the scanning rate deviation.

Claims18

Dependent claims

Horizontal scanning rate correction apparatus for a cathode-ray tube having a screen, means for projecting an electron beam upon said screen, and a beam deflection device supplied with at least horizontal and vertical beam deflection signals for causing said beam to repeatedly scan across said screen in a vertical succession of horizontal lines, said apparatus comprising:

memory means for storing a plurality of correction values representing deviations of the horizontal scanning rate of said beam from a desired scanning rate at a plurality of predetermined horizontal sampling positions along each of a plurality of predetermined sampling lines from among said horizontal lines;
reading means for reading a selected one of said stored correction values for each horizontal scanning position of said electron beam along a scanned one of said horizontal lines, each correction value that is read representing said deviation at a corresponding one of said horizontal sampling positions on one of said sampling lines, said reading means including means for producing a sampling line correction signal corresponding to each of said read correction values;
means for producing, for each said horizontal scanning position, a scanned line correcion signal which is an interpolated function of the sampling line correction signal of the last-scanned sampling line, the corresponding sampling line correction of the next-to-be-scanned sampling line, and the vertical position of the respective scanned line relative to said last-scanned and said next-to-be-scanned sampling lines;
and
means for supplying said scanned line correction signal to said beam deflection device so that said deviation of the horizontal scanning rate along said scanned line is substantially cancelled.

2 more elements

memory means for storing a plurality of correction values representing deviations of the horizontal scanning rate of said beam from a desired scanning rate at a plurality of predetermined horizontal sampling positions along each of a plurality of predetermined sampling lines from among said horizontal lines, in which the number of said sampling lines is substantially less than the number of said horizontal lines;
reading means for reading a selected one of said stored correction values for each horizontal scanning position of said electron beam along a scanned one of said horizontal lines, each correction value that is read representing said deviation at a corresponding one of said horizontal sampling positions on one of said sampling lines, said reading means including means for producing a sampling line correction signal corresponding to each of said read correction values;
means for producing, for each said horizontal scanning position, a scanned line correction signal which is a function of said sampling line correction signal and the vertical position of the respective scanned line, said means for producing the scanned line correction signal being operative to adjust said sampling line correction signal in correspondence to the departure of said scanned line from said sampling line to which said read correction values correspond;
and
means for supplying said scanned line correction signal to said beam deflection device so that said deviation of the horizontal scanning rate along said scanned line is substantially cancelled.

2 more elements

Dependencies are inferred from the claim text.