Method and apparatus for providing a dynamic rotational alignment of a cathode ray tube raster
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.
1. A method of dynamically correcting, on a line by line basis, rotational distortion of a raster scan in a cathode ray tube, comprising:
generating a first correction magnetic flux component;
adding the first correction magnetic flux to a first vertical deflection magnetic flux component in real time;
generating a second correction magnetic flux component; 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 wherein the resultant magnetic flux is a substantially free of rotational distortions.
2. A method as recited in claim 1 , wherein the first correction magnetic flux and the second correction magnetic flux each has, respectively, a first correction magnetic magnitude and a second correction magnetic flux magnitude that are approximately equal to each other.
3. A method as recited in claim 1 , wherein the first correction magnetic flux is added during a first scan and wherein the second correction magnetic flux is added during a second scan wherein the first polarity is approximately 180 degrees out of phase from the second polarity.
4. A method as recited in claim 1 , wherein the resultant magnetic flux is adjusted during a line time to uniformly separate the lines.
5. A twister coil arranged to correct, on a line by line basis, rotational distortion of a raster scan in a cathode ray tube having a deflection yoke, a vertical deflection coil, and a horizontal deflection coil, comprising:
a first correction magnetic flux component generator unit for generating a first correction magnetic flux component that is added to a first vertical deflection magnetic flux component in real time;
a second correction magnetic flux component generator unit for generating a second correction magnetic flux component that is added to a second vertical deflection magnetic flux component in real time thereby generating a resultant vertical deflection magnetic flux that is a substantially free of rotational distortions.
6. A twister coil as recited in claim 5 , wherein the first correction magnetic flux and the second correction magnetic flux each has, respectively, a first correction magnetic magnitude and a second correction magnetic flux magnitude that are approximately equal to each other.
7. A twister coil as recited in claim 5 , wherein the first correction magnetic flux is added during a first scan and wherein the second correction magnetic flux is added during a second scan wherein the first polarity is approximately 180 degrees out of phase from the second polarity.
8. A twister coil as recited in claim 5 , wherein the resultant magnetic flux is adjusted during a line time to uniformly separate the lines.