Method and apparatus for providing a dynamic rotational alignment of a cathode ray tube raster
AssigneeGenesis Microchip Inc.
InventorJames R. Webb
Life of this patent
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Abstract
A method and apparatus used to step and correct the position of raster lines in a sinusoidal or zig-zag deflection system. By combining the magnetic flux generated with a rotation “twister” coil and a vertical deflection coil, scan lines can be uniformly spaced and separated nearly to their ends. Accordingly, the magnetic flux generated with the twister coil is adjusted going in the left to right direction then reversed in polarity and readjusted while returning from right to left. It is this controlled twister flux that combines with the linear vertical deflection flux to straighten and then step each scan line to produce an aligned raster.
Claims15
A method of dynamically correcting, on a line by line basis, rotational distortion of a raster scan in a cathode ray tube, comprising:
- during a left to right scan,
- generating a first correction magnetic flux component having a first magnitude and a first polarity;
- adding the first correction magnetic flux to a first vertical deflection magnetic flux component in real time;
- during a next right to left scan,
- generating a second correction magnetic flux component having a second magnitude and a second polarity;
- and
- generating a resultant vertical deflection magnetic flux by adding the second correction magnetic flux to a second vertical deflection magnetic flux component in real time.
An apparatus for dynamically correcting, on a line by line basis, rotational distortion of a raster scan in a cathode ray tube having a deflection yoke, containing a vertical deflection coil, and a horizontal deflection coil, further comprising:
- a twister coil coupled to the yoke arranged to provide,
- during a left to right scan,
- a first correction magnetic flux component having a first magnitude and a first polarity,
- during a next right to left scan,
- a second correction magnetic flux component having a second magnitude and a second polarity, wherein a resultant vertical deflection magnetic flux is provided by adding the second correction magnetic flux to a second vertical deflection magnetic flux component in real time.
A rotational distortion correction circuit arranged to correct rotational distortion in a raster scan displayed on a cathode ray tube (CRT) coupled thereto having a deflection yoke, comprising:
- a line twister coil arranged to provide
- during a left to right scan,
- a first correction magnetic flux component having a first magnitude and a first polarity,
- during a next right to left scan,
- a second correction magnetic flux component having a second magnitude and a second polarity, wherein a resultant vertical deflection magnetic flux is provided by adding the second correction magnetic flux to a second vertical deflection magnetic flux component in real time;
- and
- a current amplifier coupled to the line twister coil arranged to provide a controlled current to the line twister coil.
Dependencies are inferred from the claim text.