US 5,345,280 AGranted

Digital convergence correction system and method for preparing correction data

AssigneeHitachi, Ltd.

InventorsYuichiro Kimura, Yasuji Noguchi, Kuninori Matsumi

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Abstract

A digital convergence correction system and a method of preparing a convergence correction data used for an image display unit, including at least one cathode ray tube, are disclosed. Correction data at correction points at predetermined between adjusting points providing representative correction points are determined by interpolation. A whole section subjected to correction is segmented into a plurality of sub-sections. An interpolating function for each sub-section is an independent low-order function. The values of the interpolating functions for adjacent sub-sections sandwiching a boundary, i.e., an adjusting point, the values of the first order derivatives and the values of the second order derivatives, respectively, are rendered to be equal to each other at such adjusting point.

Claims43

Dependent claims

A digital convergence correction system used for convergence correction on a screen of a display unit including at least a cathode ray tube, comprising:

first memory means for storing convergence correction data for a plurality convergence adjusting points selected at predetermined intervals on the screen;
interpolating operation means for preparing correction data for a plurality of correction points between adjacent adjusting points by an interpolating operation from the correction data read from the first memory means;
second memory means for storing the correction data for the adjusting points and the correction data obtained by the interpolating operation;
means for generating a memory address associated with each position on the screen in synchronism with the scanning line and reading correction data associated with each screen position from the second memory means in accordance with the memory address;
and
means for converting said correction data read into an analog signal and driving a convergence yoke of the cathode ray tube,
wherein the interpolating operation is a combination of one-dimensional interpolating operations for horizontal and vertical directions on the screen, each of a plurality of sets of adjacent adjusting points on a section subjected to the interpolating operation in each of horizontal and vertical directions on the screen defines a sub-section, and wherein each one-dimensional interpolating operation sets an interpolating function for determining correction data for a plurality of correction points in each sub-section in such a manner that:
values of interpolating functions for two adjacent sub-sections sandwiching an adjusting point are equal to each other at said adjusting point, and
values of at least the first order derivatives of the interpolating functions for the two adjacent subsections sandwiching the adjusting point are also equal to each other at said adjusting point.

6 more elements

A convergence correction data preparation system used for convergence correction on a screen of a display unit including at least one cathode ray tube, comprising:

memory means for storing correction data at each of a plurality of convergence adjusting points selected at predetermined intervals on the screen;
and
interpolating operation means for preparing the correction data by an interpolating operation at predetermined correction point between adjusting points using the correction data for the adjusting points read from the memory means;
wherein said interpolating operation is a combination of one-dimensional interpolating operations associated with horizontal and vertical directions respectively on the screen, each set of adjacent adjusting points on a section subjected to interpolation in each of horizontal and vertical directions on the screen defines a sub-section, and wherein each one-dimensional interpolating operation sets correction data at correction points in the sub-section in such a manner that values of interpolating functions for adjacent two sub-sections sandwiching and adjusting point match each other at said adjusting point and values of at least first order derivatives thereof also match each other at said adjusting point.

1 more element

A method of convergence correction on a screen of a display unit using at least one cathode ray tube, comprising the steps of:

determining in advance and storing in a memory correction data for convergence adjusting points selected at predetermined intervals on the screen;
reading the correction data from the memory;
determining correction data by an interpolating operation at a predetermined correction point between adjacent adjusting points by use of the correction data read out of the memory;
and
correcting the convergence of the display unit on the basis of the correction data determined,
wherein said interpolating operation is a combination of one-dimensional interpolating operations associated with horizontal and vertical directions respectively of the screen, each of a plurality of sets of adjacent adjusting points on a section subjected to the interpolating operation defines a sub-section, and wherein each of the one-dimensional interpolation operations sets an interpolating function for determining correction data at correction points in said sub-section in such a manner that the values of interpolating functions for two adjacent sub-sections sandwiching an adjusting point are continuous at said adjusting point and the values of at least the first order derivatives thereof are also continuous at said adjusting point.

3 more elements

An image display apparatus comprising:

at least a cathode ray tube including a convergence yoke;
a deflection circuit connected to said cathode ray tube;
a video circuit having an output connected to said cathode ray tube;
a video signal input terminal;
a pattern generator for generating a pattern signal for convergence adjustment;
switching means for selectively applying one of the input of said video signal and the output of said pattern generator to said video circuit;
and
a convergence correction device having an output connected to said convergence yoke for correcting the convergence of the screen when the convergence adjustment pattern is projected on the screen of the cathode ray tube, said convergence correction device including convergence correction data preparation means which includes:
memory means for storing correction data for each convergence adjusting point selected at predetermined intervals on the screen;
and
interpolating operation means for preparing correction data by interpolation at predetermined correction points between adjusting points by use of the correction data for the adjusting point read from said memory means,
wherein said interpolating operation means performs an interpolating operation which is a combination of one-dimensional interpolating operations corresponding respectively to the horizontal and vertical directions of the screen, each set of adjacent adjusting points in a section subjected to interpolation defines a sub-section in horizontal and vertical directions on the screen, and wherein said one-dimensional interpolating operation sets correction data for correction points in said sub-section in such a manner that values of interpolating functions for two adjacent sub-sections sandwiching an adjusting point match each other at said adjusting point, and values of at least the first order derivatives also match each other at said adjusting point.

9 more elements

Dependencies are inferred from the claim text.