Information
-
Patent Grant
-
6522091
-
Patent Number
6,522,091
-
Date Filed
Wednesday, October 17, 200123 years ago
-
Date Issued
Tuesday, February 18, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 315 370
- 315 371
- 315 391
- 315 393
- 315 397
- 315 399
- 315 364
- 315 403
-
International Classifications
-
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.
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