Circuit and method that allows the amplitudes of vertical correction signal components to be adjusted independently

Information

  • Patent Grant
  • 6522091
  • Patent Number
    6,522,091
  • Date Filed
    Wednesday, October 17, 2001
    23 years ago
  • Date Issued
    Tuesday, February 18, 2003
    21 years ago
Abstract
The present disclosure describes a technique that allows the amplitudes of vertical correction signal components to be adjusted independently. When the amplitude of each of the vertical correction signal components are set, they will not have to be readjusted when the amplitudes of the other vertical correction signal components are set. This greatly simplifies the process of setting the amplitudes of the vertical correction signal components, saving time and increasing the accuracy of the settings.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to a raster display system and, more particularly, to a circuit and method that allows the amplitudes of vertical correction signal components to be adjusted independently.




2. Related Art




Raster display system are used in a variety of application such as televisions and computer displays.

FIG. 1A

shows a cross-sectional side view of a conventional raster display system


100


. Raster display system


100


includes an electron gun


110


, a deflection system


120


, and a screen


130


. Electron gun


110


generates and accelerates an electron beam


115


toward deflection system


120


. Deflection system


120


deflects electron beam


115


horizontally and/or vertically at screen


130


. Screen


130


includes a phosphor-coated faceplate that glows or phosphoresces when struck by electron beam


115


.




Deflection system


120


includes a horizontal deflection generator


122


, a horizontal deflection coil


124


, a vertical deflection generator


126


, and a vertical deflection coil


128


. Horizontal deflection coil


124


and vertical deflection coil


128


are collectively referred to as the yoke. Although not shown, horizontal deflection coil


124


and vertical deflection coil


128


are wound a ninety-degree angle relative to one another. Horizontal deflection generator


122


generates a horizontal deflection current signal I


H


. When horizontal deflection current signal I


H


passes through horizontal deflection coil


124


, a magnetic field is created that deflects electron beam


115


horizontally. The horizontal angle of deflection (not shown) is proportional to the direction and the magnitude of horizontal deflection current signal I


H


. Similarly, vertical deflection generator


126


generates a vertical deflection current signal I


V


. When vertical deflection current signal I


V


passes through vertical deflection coil


128


, a magnetic field is created that deflects electron beam


115


vertically. The vertical angle of deflection θ is proportional to the direction and the magnitude of vertical deflection current signal I


V


.





FIG. 1B

is a front view of raster display system


100


. Deflection system


120


deflects electron beam


115


from a first side of screen


130


to a second side of screen


130


to draw a first line L


1


. Electron beam


115


is then briefly turned off, moved downward, and brought back to the first side of screen


130


by deflection system


120


. Electron beam


115


is then turned on and deflection system


120


deflects electron beam


115


from the first side of screen


120


to the second side of screen


130


to draw a second line L


2


. This process continues very rapidly so that lines L


3


through L


N


(where N=1, 2, 3, . . . , N) are drawn thereby creating a raster on screen


130


.




To produce an accurate image, the distance d


N


(where n=1, 2, 3, . . . , N) between each horizontal line L


N


drawn on screen


130


must be equal as shown in FIG.


1


B. The distance between each horizontal line d


N


is a function of two factors: the vertical angle of deflection θ and the shape of screen


130


. If the shape of the screen is spherical, a vertical deflection current signal I


V


having a sawtooth shaped waveform can be used. A sawtooth shaped waveform can be used since the distance from the point of deflection


129


to the upper, center, and lower portions of the curved screen is constant. If the shape of the screen is non-spherical (e.g., a flat screen), a vertical deflection current signal I


V


having a more complex S-shaped waveform must be used. An S-shaped waveform must be used since the distance from the point of deflection


129


to the upper and lower portions of a non-spherical screen is greater than the distance from the point of deflection


129


to the center portions of a non-spherical screen. Note that if the shape of the screen is non-spherical and a vertical deflection current signal I


V


having a sawtooth shaped waveform is used, the distance d


N


between horizontal lines L


N


drawn on screen


130


will not be an equal from one another as shown in FIG.


1


C. This degrades the quality of the image drawn on screen


130


and thus is commercially undesirable.




As is well-known in the art, an S-shaped waveform can be produced by combining a sawtooth waveform with higher-order odd multiples of the sawtooth waveform. In particular, S-shaped waveforms be produced by combining the following components: a first-order signal component (i.e., a sawtooth signal), a third-order signal component, and a fifth-order signal component. Other higher-order odd signal components can also be combined with the sawtooth waveform to produce a more complex S-shaped waveform.

FIG. 2

shows waveforms for a first-order signal component


210


, a third-order signal component


220


, and a fifth-order signal component


230


, respectively.





FIG. 3

shows a conventional horizontal deflection generator circuit


300


that can be used to generate a vertical deflection current signal I


V


having an S-shaped waveform. Horizontal deflection generator circuit


300


includes a first-order signal generator


302


, a first-order amplitude signal generator


304


, a multiplier


306


, a third-order signal generator


308


, a third-order amplitude signal generator


310


, a multiplier


312


, a fifth-order signal generator


314


, a fifth-order amplitude signal generator


316


, a multiplier


318


, and a signal combiner


320


.




In operation, first-order signal generator


302


generates a first-order signal S


1


and first-order amplitude signal generator


304


generates a first-order amplitude signal A


1


. Multiplier


306


multiplies first-order signal S


1


with first-order amplitude signal A


1


to generate a first-order vertical correction signal component A


1


S


1


. Third-order signal generator


308


generates a third-order signal S


3


and third-order amplitude signal generator


310


generates a third-order amplitude signal A


3


. Multiplier


312


multiplies third-order signal S


3


with third-order amplitude signal A


3


to generate a third-order vertical correction signal component A


3


S


3


. Fifth-order signal generator


314


generates a fifth-order signal S


5


and fifth-order amplitude signal generator


316


generates a fifth-order amplitude signal A


5


. Multiplier


318


multiplies fifth-order signal S


5


with fifth-order amplitude signal A


5


to generate a fifth-order vertical correction signal component A


5


S


5


.




Signal combiner


320


combines the vertical correction signal components A


1


S


1


, A


3


S


3


, and A


5


S


5


to produce vertical correction signal A


V


S


V


. Vertical correction signal A


V


S


V


can be equivalent to vertical deflection current signal I


V


, or vertical correction signal A


V


S


V


can be further processed (e.g., amplified) prior to becoming vertical deflection current signal I


V


.




During the manufacturing process of a raster display system, a user must adjust amplitude signals A


1


, A


3


, and A


5


so that lines L


1


through line L


N


(where N=1, 2, 3, . . . , N) are properly drawn on screen


130


. First, the user adjusts amplitude signal A


1


so that line L


1


is drawn at the proper position at the top of screen


130


. This is referred to as setting the vertical size (i.e., the maximum angle of vertical deflection θ


MAX


). Next, the user adjusts amplitude signals A


3


and A


5


so that the distances d


N


between each horizontal line L


N


drawn on screen


130


are equal as shown in FIG.


1


B. Unfortunately, when the user adjusts amplitude signals A


3


and A


5


, the vertical size changes. As a result, the user must readjust amplitude signal A


1


to reposition line L


1


at the proper position at the top of screen


130


. However, the readjustment of amplitude signal A


1


causes the distances d


N


between each horizontal line L


N


drawn on screen


130


to become unequal again. Consequently, the user must readjust amplitude signals A


3


and A


5


so that the distances d


N


between each horizontal line L


N


drawn on screen


130


are equal. Unfortunately, the adjustment of amplitude signals A


3


and A


5


again causes the vertical size to change. As a result, the user must readjust amplitude signal A


1


to reposition line L


1


at the proper position at the top of screen


130


. This time-consuming, inexact, trial-and-error process must be performed numerous times before amplitude signals A


1


, A


3


, and A


5


are properly set.




Accordingly, what is needed is a circuit and method that allows the amplitudes of vertical correction signal components to be adjusted independently.




SUMMARY OF THE INVENTION




The present invention provides a technique that allows the amplitudes of vertical correction signal components to be adjusted independently. When the amplitude of each of the vertical correction signal components are set, they will not have to be readjusted when the amplitudes of the other vertical correction signal components are set. This greatly simplifies the process of setting the amplitudes of the vertical correction signal components, saving time and increasing the accuracy of the settings.




In one embodiment of the present invention, a circuit that allows the amplitudes of vertical correction signal components to be adjusted independently is provided. The circuit includes a first signal combiner having a first input coupled to




receive a first-order amplitude signal and a second input coupled to receive a third-order amplitude signal, a first multiplier having a first input coupled to receive a first-order signal and a second input coupled to receive an output signal of the first signal combiner, a second multiplier having a first input coupled to receive a third-order signal and a second input coupled to receive the third-order amplitude signal, and a second signal combiner having a first input coupled to receive an output signal of the first multiplier and a second input coupled to receive an output signal of the second multiplier.




In another embodiment of the present invention, a method that allows the amplitudes of vertical correction signal components to be adjusted independently is provided. The method includes combining a first-order amplitude signal with a third-order amplitude signal to generate a modified first-order amplitude signal, multiplying a first-order signal with the modified first-order amplitude signal to generate a first-order vertical correction signal component, multiplying a third-order signal with the third-order amplitude signal to generate a third-order vertical correction signal component, and combining the first-order vertical correction signal component with the third-order vertical correction signal component.




In another embodiment of the present invention, a method for generating a vertical deflection current signal including a first vertical correction signal component and a second vertical correction component is provided. The method includes setting an amplitude of the first vertical correction signal component, and setting an amplitude of the second vertical correction signal component, wherein the amplitude of the first vertical correction signal component will not have to be reset after the amplitude of the second vertical correction signal component has been set.




Other embodiments, aspects, and advantages of the present invention will become apparent from the following descriptions and the accompanying drawings.











BRIEF DESCRIPTION OF THE DRAWINGS




For a more complete understanding of the present invention and for further embodiments, aspects, and advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:





FIG. 1A

shows a cross-sectional side view of a conventional raster display system.





FIG. 1B

shows a front view of a raster display system.





FIG. 1C

shows a front view of a raster display system.





FIG. 2

shows waveforms for a first-order signal, a third-order signal, and a fifth-order signal.





FIG. 3

shows a conventional vertical deflection generator circuit.





FIG. 4

shows a vertical deflection generator circuit, according to some embodiments of the present invention.





FIG. 5

shows a flowchart of an exemplary method of operation for the vertical deflection generator circuit of

FIG. 4

, according to some embodiments of the present invention.





FIG. 6

shows a vertical deflection generator circuit that allows for independent S corrections to the top half and the bottom half of a raster display, according to some embodiments of the present invention.











DETAILED DESCRIPTION OF THE INVENTION




The preferred embodiments of the present invention and their advantages are best understood by referring to

FIGS. 4 through 6

of the drawings. Like reference numerals are used for like and corresponding parts of the various drawings.




Circuit that Allows the Amplitudes of Vertical Correction Signal Components to be Adjusted Independently





FIG. 4

shows a deflection generator circuit


400


, according to some embodiments of the present invention. Deflection generator circuit


400


allows the amplitudes of vertical correction signal components to be adjusted independently. Deflection generator circuit


400


can be implemented in hardware, firmware/microcode; software, or any combination thereof. Additionally, deflection generator circuit


400


can be implemented on a single integrated circuit device or integrated with other integrated circuits on a single integrated circuit device.




Deflection generator circuit


400


includes a first-order signal generator


402


, a first-order amplitude signal generator


404


, a multiplier


406


, a third-order signal generator


408


, a third-order amplitude signal generator


410


, a multiplier


412


, a fifth-order signal generator


414


, a fifth-order amplitude signal generator


416


, a multiplier


418


, a signal combiner


420


, and a signal combiner


422


.




First-order signal generator


402


generates a first-order signal S


1


and signal combiner


422


outputs a modified first-order amplitude signal A


1


′. Multiplier


406


multiplies first-order signal S


1


with modified first-order amplitude signal A


1


′ to generate a modified first-order vertical correction signal component A


1


′S


1


. Third-order signal generator


408


generates a third-order signal S


3


and third-order amplitude signal generator


410


generates a third-order amplitude signal A


3


. Multiplier


412


multiplies third-order signal S


3


with third-order amplitude signal A


3


to generate a third-order vertical correction signal component A


3


S


3


. Fifth-order signal generator


414


generates a fifth-order signal S


5


and fifth-order amplitude signal generator


416


generates a fifth-order amplitude signal A


5


. Multiplier


418


multiplies fifth-order signal S


5


with fifth-order amplitude signal A


5


to generate a fifth-order vertical correction signal component A


5


S


5


. For clarity, a third-order signal generator


408


and a fifth-order signal generator


414


are shown. However, it should be recognized that an independent third-order signal generator


408


and a fifth-order signal generator


414


are not needed since first-order signal S


1


can be provided to multipliers that generate third-order signal S


3


and fifth-order signal S


5


. In some embodiments, first-order amplitude signal generator


404


, third-order amplitude signal generator


410


, and fifth-order amplitude signal generator


416


are N-bit registers (where N is a positive integer) that can be programmed by a user.




Signal combiner


420


combines the vertical correction signal components A


1


′S


1


, A


3


S


3


, and A


5


S


5


to produce vertical correction signal A


V


S


V


. More specifically, signal combiner


420


subtracts vertical correction signal components A


3


S


3


and A


5


S


5


from vertical correction signal component A


1


′S′ to produce vertical correction signal A


V


S


V


. Vertical correction signal A


V


S


V


can be equivalent to vertical deflection current signal I


V


, or vertical correction signal A


V


S


V


can be further processed (e.g., amplified) prior to becoming vertical deflection current signal I


V


.




Signal combiner


422


combines first-order amplitude signal A


1


, which is generated by first-order amplitude signal generator


404


, with third-order amplitude signal A


3


, and fifth-order amplitude signal A


5


to generate modified first-order amplitude signal A


1


′. More specifically, signal combiner


422


adds third-order amplitude signal A


3


and fifth-order amplitude signal A


5


to first-order amplitude signal A


1


to produce modified first-order amplitude signal A


1


′. As described above, modified first-order amplitude signal A


1


′ is then multiplied with first-order signal S


1


to generate modified first-order vertical correction signal component A


1


′S


1


.




The reason that third-order amplitude signal A


3


and fifth-order amplitude signal A


5


are added to first-order amplitude signal A


1


in signal combiner


422


is because third-order amplitude signal A


3


and fifth-order amplitude signal A


5


are subtracted from modified first-order amplitude signal A


1


′ in signal combiner


420


. When third-order amplitude signal A


3


and fifth-order amplitude signal A


5


are subtracted from modified first-order amplitude signal A


1


′ in signal combiner


420


, the amplitude A


V


of vertical correction signal A


V


S


V


decreases. However, as explained above, the amplitude A


V


of vertical correction signal A


V


S


V


should remain constant so that the vertical size remains constant. By adding third-order amplitude signal A


3


and fifth-order amplitude signal A


5


to first-order amplitude signal A


1


in signal combiner


422


, the amplitude of modified first-order amplitude signal A


1


′ is increased and thus compensates for the decrease in the amplitude A


V


of vertical correction signal A


V


S


V


. Consequently, first-order amplitude signal A


1


will not have to be readjusted after third-order amplitude signal A


3


and fifth-order amplitude signals A


5


have been set. As those of skill in the art will recognize, this greatly simplifies the process setting amplitude signals A


1


, A


3


, and A


5


.




It should be recognized that deflection generator circuit


400


can also include other circuitry. For example, deflection generator circuit


400


may include a second-order signal generator, a second-order amplitude signal generator, and a multiplier for multiplying the second-order signal with the second-order amplitude signal to produce a second-order vertical correction signal component. The second-order vertical correction signal component can then be combined with the other vertical correction signal components in signal combiner


420


. The second-order vertical correction signal provides what is commonly referred to as C correction. The second-order vertical correction signal or C correction signal is used to compensate for top/bottom asymmetry in the vertical deflection coil.




Method that Allows the Amplitudes of Vertical Correction Signal Components to be Adjusted Independently





FIG. 5

is a flowchart of an exemplary method


500


of operation for vertical deflection generator circuit


400


. Method


500


describes how the amplitudes of vertical correction signal components can be adjusted independently. Method


500


can be performed by a human operator, by automated devices, or by any combination thereof, and method


500


can be performed using hardware, firmware/microcode, software, or any combination thereof. Additionally, method


500


can be performed on a single integrated circuit device.




In step


502


, first-order amplitude signal A


1


, third-order amplitude signal A


3


, and fifth-order amplitude signal A


5


are set to predetermined values. The predetermined values can be optimal values that have been determined from testing. This step can be accomplished by programming first-order amplitude signal generator


404


, third-order amplitude signal generator


410


, and fifth-order amplitude signal generator


416


to output predetermined values.




In step


504


, the amplitude of first-order amplitude signal A


1


is set. More specifically, the amplitude of first-order amplitude signal A


1


is set such that vertical correction signal A


V


S


V


causes the electron beam to be positioned at a desired position at the top of a screen. This is generally referred to as setting the vertical size.




In step


506


, the amplitude of third-order amplitude signal A


3


is set. Third-order amplitude signal A


3


introduces third-order non-linearities into vertical correction signal A


V


S


V


. The third-order non-linearities make vertical correction signal A


V


S


V


non-linear or S-shaped and thus correct for the non-spherical shape of the screen.




In step


508


, third-order amplitude signal A


3


is added to first-order amplitude signal A


1


. In this step, third-order amplitude signal A


3


is fed into signal combiner


422


where it is added to first-order amplitude signal A


1


to generate modified first-order amplitude signal A


1


′. The reason third-order amplitude signal A


3


is added to first-order amplitude signal A


1


is because third-order vertical correction signal component A


3


S


3


now exists and is subtracted from modified first-order vertical correction signal component A


1


′S


1


in signal combiner


420


. When third-order vertical correction signal component A


3


S


3


is subtracted from modified first-order vertical correction signal component A


1


′S


1


, the amplitude A


V


of vertical correction signal A


V


S


V


decreases. However, as explained above, the amplitude A


V


of vertical correction signal A


V


S


V


should remain constant so that the vertical size remains constant. By adding third-order amplitude signal A


3


to first-order amplitude signal A


1


in signal combiner


422


, the amplitude of modified first-order amplitude signal A


1


′ is increased and thus compensates for the decrease in the amplitude A


V


of vertical correction signal A


V


S


V


. Consequently, first-order amplitude signal A


1


will not have to be readjusted after third-order amplitude signal A


3


has been set. As those of skill in the art will recognize, this greatly simplifies the process setting amplitude signals A


1


and A


3


.




In step


510


, the amplitude of fifth-order amplitude signal A


5


is set. Fifth-order amplitude signal A


5


introduces fifth-order non-linearities into vertical correction signal A


V


S


V


. The fifth-order non-linearities make vertical correction signal A


V


S


V


non-linear or S-shaped and thus correct for the flatness of the screen. Fifth-order non-linearities are typically introduced when the third-order non-linearities (introduced in step


506


) do not adequately correct for the non-spherical shape of a screen. It should be recognized that higher-order amplitude signals can also be introduced into vertical correction signal A


V


S


V


.




In step


512


, fifth-order amplitude signal A


5


is added to first-order amplitude signal A


1


. In this step, fifth-order amplitude signal A


5


is fed into signal combiner


422


where it is added to first-order amplitude signal A


1


and third-order amplitude signal A


3


to generate modified first-order amplitude signal A


1


′. The reason fifth-order amplitude signal A


5


is added to first-order amplitude signal A


1


and third-order amplitude signal A


3


is because fifth-order vertical correction signal component A


5


S


5


now exists and is subtracted from modified first-order vertical correction signal component A


1


′S


1


. When fifth-order vertical correction signal component A


5


S


5


is subtracted from modified first-order vertical correction signal component A


1


′S


1


the amplitude A


V


of vertical correction signal A


V


S


V


decreases. However, as explained above, the amplitude A


V


of vertical correction signal A


V


S


V


should remain constant so that the vertical size remains constant. By adding fifth-order amplitude signal A


5


to first-order amplitude signal A


1


and third-order amplitude signal A


3


in signal combiner


422


, the amplitude of modified first-order amplitude signal A


1


′ is increased and thus compensates for the decrease in the amplitude A


V


of vertical correction signal A


V


S


V


. Consequently, first-order amplitude signal A


1


will not have to be readjusted after third-order amplitude signal A


3


has been set. As those of skill in the art will recognize, this greatly simplifies the process setting amplitude signals A


1


, A


3


, and A


5


.




When compared with conventional techniques, method


500


is advantageous since a user will not have to make successive adjustments to amplitude signals A


1


, A


3


, and A


5


. Consequently, method


500


greatly simplifies the process setting amplitude signals A


1


, A


3


, and A


5


.




Circuit that Allows the Amplitudes of Vertical Correction Signal Components to be Adjusted Independently and that Allows for Independent Top and Bottom S Corrections





FIG. 6

shows a deflection generator circuit


600


, according to some embodiments of the present invention. Deflection generator circuit


600


is similar to deflection generator circuit


400


. However, in addition to allowing the amplitudes of vertical correction signal components to be adjusted independently, deflection generator circuit


600


also allows for independent S corrections to the top half and the bottom half of a raster display using independent top-bottom correction circuit


670


. Deflection generator circuit


600


can be implemented in hardware, firmware/microcode, software, or any combination thereof. Additionally, deflection generator circuit


600


can be implemented on a single integrated circuit device or integrated with other integrated circuits on a single integrated circuit device.




Deflection generator circuit


600


includes a first-order signal generator


602


, a first-order amplitude signal generator


604


, a multiplier


606


, a third-order signal generator


608


, a third-order top amplitude signal generator


610


T, a third-order bottom amplitude signal generator


610


B, a multiplexer


611


, a multiplier


612


, a fifth-order signal generator


614


, a fifth-order top amplitude signal generator


616


T, a fifth-order bottom amplitude signal generator


616


B, a multiplexer


617


, a multiplier


618


, a signal combiner


620


, a signal combiner


622


, a control signal generator


640


, signal combiners


642


,


644


,


646


, and


648


, divide-by-two elements


650


and


652


, a DC signal generator


658


, and signal combiners


660


, and


662


.




Independent top-bottom correction circuit


670


includes third-order top amplitude signal generator


610


T, third-order bottom amplitude signal generator


610


B, multiplexer


611


, fifth-order top amplitude signal generator


616


T, fifth-order bottom amplitude signal generator


616


B, multiplexer


617


, signal combiners


642


,


644


,


646


, and


648


, and divide-by-two elements


650


and


652


.




First-order signal generator


602


generates a first-order signal S


1


and signal combiner


622


outputs a modified first-order amplitude signal A


1


′. Multiplier


606


multiplies first-order signal S


1


with modified first-order amplitude signal A


1


′ to generate a modified first-order vertical correction signal component A


1


′S


1


.




Third-order signal generator


608


generates a third-order signal S


3


. Third-order top amplitude signal generator


610


T generates a third-order top amplitude signal A


3T


, and third-order bottom amplitude signal generator


610


B generates a third-order bottom amplitude signal A


3B


. Multiplexer


611


outputs a third-order amplitude signal A


3


, which is either third-order top amplitude signal A


3T


or third-order bottom amplitude signal A


3B


depending on the value of control signal C. Multiplier


612


multiplies third-order signal S


3


with third-order amplitude signal A


3


to generate a third-order vertical correction signal component A


3


S


3


.




Fifth-order signal generator


614


generates a fifth-order signal S


5


. Fifth-order top amplitude signal generator


616


T generates a fifth-order top amplitude signal A


5T


, and fifth-order bottom amplitude signal generator


616


B generates a fifth-order bottom amplitude signal A


5B


. Multiplexer


617


outputs a fifth-order amplitude signal A


5


, which is either fifth-order top amplitude signal A


5T


or fifth-order bottom amplitude signal A


5B


depending on the value of control signal C. Multiplier


618


multiplies fifth-order signal S


5


with fifth-order amplitude signal A


5


to generate a fifth-order vertical correction signal component A


5


S


5


.




For clarity, a third-order signal generator


608


and a fifth-order signal generator


614


are shown. However, it should be recognized that an independent third-order signal generator


608


and a fifth-order signal generator


614


are not needed since first-order signal S


1


can be provided to multipliers that generate third-order signal S


3


and fifth-order signal S


5


. In some embodiments, first-order amplitude signal generator


604


, third-order top amplitude signal generator


610


T, third-order bottom amplitude signal generator


610


B, fifth-order top amplitude signal generator


616


T, and fifth-order bottom amplitude signal generator


616


B are N-bit registers (where N is a positive integer) that can be programmed by a user.




Control signal generator


640


generates control signal C. More specifically, control signal generator


640


receives first-order signal S


1


(i.e., a sawtooth signal) and determines whether the current value of first-order signal S


1


is positive or negative. When the current value of first-order signal S


1


is positive, the top half of the raster display is being drawn and control signal generator


640


outputs a logic low signal for control signal C. This causes third-order top amplitude signal A


3T


to be output from multiplexer


611


as third-order amplitude signal A


3


, and causes fifth-order top amplitude signal A


5T


to be output from multiplexer


617


as fifth-order amplitude signal A


5


. When the current value of first-order signal S


1


is negative, the bottom half of the raster display is being drawn and control signal generator


640


output a logic high signal for control signal C. This causes third-order bottom amplitude signal A


3B


to be output from multiplexer


611


as third-order amplitude signal A


3


, and causes fifth-order bottom amplitude signal A


5B


to be output from multiplexer


617


as fifth-order amplitude signal A


5


. Accordingly, the amplitudes of third-order vertical correction signal component A


3


S


3


and fifth-order vertical correction signal component A


5


S


5


can be independently controlled for the top and bottom halves of the raster display.




Signal combiner


620


combines the vertical correction signal components A


1


′S


1


, A


3


S


3


, and A


5


S


5


to produce vertical correction signal A


V


S


V


. More specifically, signal combiner


620


subtracts vertical correction signal components A


3


S


3


and A


5


S


5


from vertical correction signal component A


1


′S to produce vertical correction signal A


V


S


V


.




Signal combiner


622


combines first-order amplitude signal A


1


generated by first-order amplitude signal generator


604


with signal A


3,5


to generate modified first-order amplitude signal A


1


′. More specifically, signal combiner


622


adds signal A


3,5


to first-order amplitude signal A


1


to produce modified first-order amplitude signal A


1


′. As described above, modified first-order amplitude signal A


1


′ is then multiplied with first-order signal S


1


to generate modified first-order vertical correction signal component A


1


′S


1


. Signal A


3,5


is generated by independent top and bottom correction circuit


670


and can be described by the following equation: A


3,5


=(A


3T


+A


5T


)/2+(A


3B


+A


5B


)/2.




Signal combiner


660


combines signal A′


3,5


and signal A


DC


to generate a vertical position signal A


VP


. Signal A


DC


is generated by DC signal generator


658


and is used to control the vertical position of the electron beam. Signal A′


3,5


is generated by independent top and bottom correction circuit


670


and can be described by the following equation: A′


3,5


=(A


3T


+A


5T


)/2−(A


3B-A




5B


)/2.




Signal combiner


662


combines vertical correction signal A


V


S


V


and vertical position signal A


VP


to generate vertical correction signal A′


V


S


V


′. Vertical correction signal A′


V


S


V


′ can be equivalent to vertical deflection current signal I


V


, or vertical correction signal A′


V


S


V


′ can be further processed (e.g., amplified) prior to becoming vertical deflection current signal I


V


.




It should be recognized that deflection generator circuit


600


can also include other circuitry. For example, deflection generator circuit


600


may include a second-order signal generator, a second-order amplitude signal generator, and a multiplier for multiplying the second-order signal with the second-order amplitude signal to produce a second-order vertical correction signal component. The second-order vertical correction signal component can then be combined with the other vertical correction signal components in signal combiner


620


. The second-order vertical correction signal provides what is commonly referred to as C correction. The second-order vertical correction signal or C correction signal is used to compensate for asymmetry in the vertical deflection coil.




While particular embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspect and, therefore, the appended claims are to encompass within their scope all such changes and modifications as fall within the true spirit of this invention.



Claims
  • 1. A circuit that allows the amplitudes of vertical correction signal components to be adjusted independently, the circuit comprising:a first signal combiner having a first input coupled to receive a first-order amplitude signal and a second input coupled to receive a third-order amplitude signal; a first multiplier having a first input coupled to receive a first-order signal and a second input coupled to receive an output signal of the first signal combiner; a second multiplier having a first input coupled to receive a third-order signal and a second input coupled to receive the third-order amplitude signal; and a second signal combiner having a first input coupled to receive an output signal of the first multiplier and a second input coupled to receive an output signal of the second multiplier.
  • 2. The circuit of claim 1 wherein the first signal combiner includes a third input coupled to receive a fifth-order amplitude signal.
  • 3. The circuit of claim 1 further comprising a third multiplier having a first input coupled to receive a fifth-order signal and a second input coupled to receive a fifth-order amplitude signal.
  • 4. The circuit of claim 1 wherein the second signal combiner includes a third input coupled to receive an output signal of a third multiplier.
  • 5. The circuit of claim 1 further comprising a fourth multiplier having a first input coupled to receive a second-order signal and a second input coupled to receive a second-order amplitude signal.
  • 6. The circuit of claim 1 wherein the second signal combiner includes a third input coupled to receive an output signal of a fourth multiplier.
  • 7. The circuit of claim 1 further comprising:a first-order signal generator operable to generate the first-order signal; and a third-order signal generator operable to generate the third-order signal.
  • 8. The circuit of claim 1 further comprising:a first-order amplitude signal generator operable to generate the first-order amplitude signal; and a third-order amplitude signal generator operable to generate the third-order amplitude signal.
  • 9. The circuit of claim 1 further comprising an independent top and bottom correction circuit that allows for independent S corrections to the top half and the bottom half of a raster display.
  • 10. The circuit of claim 1 wherein the circuit is implemented on a single integrated circuit device.
  • 11. A method that allows the amplitudes of vertical correction signal components to be adjusted independently, the method comprising:combining a first-order amplitude signal with a third-order amplitude signal to generate a modified first-order amplitude signal; multiplying a first-order signal with the modified first-order amplitude signal to generate a first-order vertical correction signal component; multiplying a third-order signal with the third-order amplitude signal to generate a third-order vertical correction signal component; and combining the first-order vertical correction signal component with the third-order vertical correction signal component.
  • 12. The method of claim 11 further comprising combining the first-order amplitude signal with the third-order amplitude signal and a fifth-order amplitude signal to generate the modified first-order amplitude signal.
  • 13. The method of claim 11 further comprising multiplying a fifth-order signal with a fifth-order amplitude signal to generate a fifth-order vertical correction signal component.
  • 14. The method of claim 11 further comprising combining the first-order vertical correction signal component with the third-order vertical correction signal component and a fifth-order vertical correction signal component.
  • 15. The method of claim 11 further comprising multiplying a second-order signal with a second-order amplitude signal to generate a second-order vertical correction signal component.
  • 16. The method of claim 11 further comprising combining the first-order vertical correction signal component with the third-order vertical correction signal component and a second-order vertical correction signal component.
  • 17. The method of claim 11 further comprising:generating the first-order signal; and generating the third-order signal.
  • 18. The method of claim 11 further comprising:generating the first-order amplitude signal; and generating the third-order amplitude signal.
  • 19. The method of claim 11 further comprising:generating a third-order top amplitude signal; generating a third-order bottom amplitude; and generating the third-order amplitude signal by selecting the third-order top amplitude signal or the third-order bottom amplitude signal.
  • 20. The method of claim 11 wherein the method is performed on a single integrated circuit device.
  • 21. A method for generating a vertical deflection current signal including a first vertical correction signal component and a second vertical correction component, the method comprising:setting an amplitude of the first vertical correction signal component; and setting an amplitude of the second vertical correction signal component, wherein the amplitude of the first vertical correction signal component will not have to be reset after the amplitude of the second vertical correction signal component has been set.
  • 22. The method of claim 21 further comprising:setting an amplitude of a third vertical correction signal component, wherein the vertical deflection current signal includes the third vertical correction signal component, and wherein the amplitude of the first vertical correction signal component will not have to be reset after the amplitude of the third vertical correction signal component has been set.
  • 23. The method of claim 21 wherein the method is performed on a single ted circuit device.
US Referenced Citations (7)
Number Name Date Kind
4642530 Rodriguez-Cavazos Feb 1987 A
4687972 Haferl Aug 1987 A
5583400 Hulshof et al. Dec 1996 A
5814952 Maige et al. Sep 1998 A
5877599 Hojabri Mar 1999 A
6081078 Truskalo et al. Jun 2000 A
6452347 Yamate et al. Sep 2002 B1