JP2002027280A - Vertical deflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the correction efficiency of vertical pin-cushion distortion. SOLUTION: The vertical deflector 2 comprising an asymmetric longitudinal convergence corrector employs first and second shunt coils and first and second capacitors in place of a conventional resistor. Consequently, correction efficiency of vertical pin-cushion distortion can be enhanced without having any effect on asymmetric longitudinal misconvergence correction even when the horizontal deflection period, i.e., the frequency of parabolic vertical pin-cushion distortion correction current, is high.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical deflection device including a device for correcting upper and lower pincushion distortions and a device for correcting asymmetric vertical misconvergence that occur when a color image is displayed by raster scanning with a color cathode ray tube. is there.

[0002]

2. Description of the Related Art When a color cathode ray tube displays a color image by performing a raster scan of an electron beam by a deflection device including a horizontal deflection coil and a vertical deflection coil, a fluorescent screen of the cathode ray tube is centered on a deflection point of the electron beam. Since it is not a spherical surface, the distance from the deflection point becomes larger near the cathode ray tube. For this reason, when the electron beam is deflected, the deflection at the four corners of the cathode ray tube which is furthest from the deflection point becomes large, and the raster is pincushion-shaped. This is called pincushion distortion, and the amount of distortion increases as the cathode ray tube has a larger deflection angle.

[0003] Therefore, pincushion distortion is corrected by changing the current flowing through the deflection coil in accordance with the deflection of the electron beam. The upper and lower pincushion distortion occurs because the upper and lower amplitudes of the raster are insufficient at the center with respect to the periphery. Since the upper and lower pincushion distortion is parabolic due to the structure of the cathode ray tube, the correction is performed by flowing a current in which a horizontal period parabolic current is superimposed on a vertical deflection current.

When a color image is displayed by performing a raster scan of an electron beam with a deflection device including a horizontal deflection coil and a vertical deflection coil in a color cathode ray tube, asymmetric vertical misconvergence (also referred to as YV misconvergence) occurs. I do. This asymmetric vertical misconvergence is a misconvergence that occurs at the top and bottom of the screen. Three electron beams corresponding to red, green, and blue are arranged side by side, that is, in a line at intervals in the scanning line direction. In this case, for example, a beam spot caused by a red electron beam is displaced upward at the upper part of the screen, for example, and is displaced downward at the lower part.

[0005] Asymmetric vertical misconvergence is caused by the asymmetry of the vertical deflection coil and the fact that the electron beam does not pass exactly through the center of the vertical deflection coil, and is solved by increasing the accuracy of the vertical deflection coil and the electron gun. Since it is difficult to perform the correction, the correction has been conventionally performed by correcting the deflection of the electron beam.

The above-described correction of the asymmetric vertical misconvergence has conventionally been performed by first and second vertical deflection coils 10.
This is performed by changing the current flowing through the transistors 6 and 108. FIG. 2 is a circuit diagram showing a conventional misconvergence correction circuit. This misconvergence correction circuit
The above-described first and second vertical deflection coils 106, 10
8 is connected to resistors 118 and 120 and a variable resistor 122.

Specifically, one terminal of the resistor 118 is
The other terminal of the resistor 118 is connected to the first terminal 124 of the variable resistor 122, and is connected to the terminal of the first vertical deflection coil 106 opposite to the second vertical deflection coil 108. One terminal of the resistor 120 is connected to the first terminal.
The other terminal of the resistor 120 is connected to a third terminal 126 of the variable resistor 122. The other terminal of the second vertical deflection coil 108 is connected to the other terminal of the variable resistor 122. Then, the second terminal 128 of the variable resistor 122
Is connected to a common connection terminal of the first and second vertical deflection coils 106 and 108. By adjusting the variable resistor 122 in such a misconvergence correction circuit,
Asymmetric vertical misconvergence can be corrected by making the currents flowing through the first and second vertical deflection coils 106 and 108 different from each other.

FIG. 3A shows a first vertical deflection coil 10.
6 is an explanatory diagram showing a magnetic field when the current flowing through 6 is larger,
(B) is an explanatory diagram showing a magnetic field when the current flowing through the second vertical deflection coil 108 is larger.

That is, the slider (connected to the second terminal 128) of the variable resistor 122 is connected to the first terminal 124.
When the magnetic field 130 is moved to the side, the current flowing through the second vertical deflection coil 108 becomes larger, and the magnetic field 130 generated by the second vertical deflection coil 108 as shown in FIG. Is larger than the magnetic field 132 generated by the first vertical deflection coil 106. As a result, the electron beam 116 is deflected by the magnetic field 130, and the electron beam 1
The electron beam 11 is deflected by a magnetic field 132.
6 deflects more than the electron beam 112.

Conversely, when the slider of the variable resistor 122 is moved to the third terminal 126 side, the first vertical deflection coil 1
06, the magnetic field 132 generated by the first vertical deflection coil 106 is higher than that of the second vertical deflection coil 1 as shown in FIG.
08 is greater than the magnetic field 130 generated. As a result, the electron beam 116 is deflected by the magnetic field 130 and the electron beam 112 is deflected by the magnetic field 132, so that the electron beam 112 is deflected more than the electron beam 116.
Therefore, by appropriately moving the slider of the variable resistor 122, the moving direction and the moving amount of the electron beams 112 and 116 on both sides can be adjusted, and the asymmetric vertical misconvergence can be corrected.

[0011]

However, a vertical deflection current in which a parabolic vertical pincushion distortion correction current having a horizontal deflection period is superimposed is supplied to a vertical deflection circuit having the above-described conventional asymmetric vertical misconvergence correction device. In this case, when the cycle of the horizontal deflection, that is, the frequency of the parabolic current is increased, there is a problem that the efficiency of the upper and lower pincushion distortion correction is deteriorated. This problem is particularly remarkable in a CRT having a large upper and lower pincushion distortion and a large deflection angle when the upper and lower pincushion distortion correction current is increased.

The cause of this is that the parabolic upper and lower pincushion distortion correction current components having a high frequency superimposed on the vertical deflection current are:
The first and second vertical deflection coils are difficult to flow. Hereinafter, this will be described in detail. FIG. 5 is a waveform diagram showing a waveform of a current flowing through a vertical deflection coil on which parabolic upper and lower pincushion distortion correction components are superimposed. As shown in this figure, the frequency of the vertical deflection current is approximately 60 Hz, and the frequency of the parabolic upper and lower pincushion distortion correction current that is the horizontal deflection period is, for example, 33.75 kHz.

Then, the inductances L1 and L2 of the first and second vertical deflection coils 106 and 108 are both set to 2.
1 mH, first and second vertical deflection coils 106, 10
8, the resistance values RL1 and RL2 are both 3.5Ω,
The resistance values R1 and R2 of the resistors 8 and 120 are both 8.2Ω, and the resistance value VR1 between the first and third terminals 124 and 126 of the variable resistor 122 is 200Ω. In addition, the variable resistor 12
The second slider is located at a midpoint between the first terminal 124 and the second terminal 126, and the first and second terminals 124,
The resistance value VR1 between the first and second terminals 128 and 126 is 100Ω, and the resistance value VR2 between the second and third terminals 128 and 126 is 100Ω.

At this time, the impedance ZL1 of the first vertical deflection coil 106 is as follows.

[0015]

(Equation 1)

Here, ω is 2πf, and the value of f is 33.75 kHz in this case. Since the current flowing through the first vertical deflection coil 106 and the current flowing through the first resistor 118 are proportional to the ratio of impedance, the relative values of the currents are assumed to be IL1 and IR1, respectively.

[0017]

(Equation 2)

## EQU1 ## Therefore, the ratio IL1 / IR1 of the current flowing through the first vertical deflection coil 106 to the current flowing through the resistor 118 has the following value.

[0019]

(Equation 3)

The current flowing through the second vertical deflection coil 108 has the same value as the current flowing through the first vertical deflection coil 106 because the circuit is symmetrical.
Current flowing through the vertical deflection coil 108 of the
Are the same.

As described above, in the case of the parabolic upper and lower pincushion distortion correction current having a high frequency, the resistance values of the first and second vertical deflection coils 106 and 108 are changed to the resistors 118 and 12.
Since the resistance value becomes larger than the resistance value of 0, it is a horizontal deflection cycle, and the parabolic upper and lower pincushion distortion correction current having a high frequency is supplied to the first and second vertical deflection coils 106 and 108 by the current of 1 It flows only about /4.12 times.

As a result, since a parabolic upper and lower pincushion distortion correction current having a high frequency hardly flows through the vertical deflection coil, the sensitivity of the upper and lower pincushion distortion correction is significantly deteriorated.

The present invention has been made to solve such a problem, and an object of the present invention is to efficiently perform upper and lower thread winding without affecting the asymmetric vertical misconvergence correction even when the frequency of the horizontal deflection current is high. An object of the present invention is to provide a device capable of correcting distortion.

[0024]

According to the present invention, a plurality of electron beams emitted from an electron gun of the color cathode ray tube are mounted on a color cathode ray tube as a deflecting device for performing a raster scan of the electron beam. A first and a second vertical deflection coil electrically arranged in series and sandwiching the first and second vertical deflection coils, wherein the first and second vertical deflection coils generate a magnetic field for performing vertical scanning; A first and a second shunt coil, a first capacitor electrically connected in parallel to the first shunt coil, and a second capacitor electrically connected in parallel to the second shunt coil , A variable resistor having first to third terminals, wherein a resistance value between the first and second terminals and a resistance value between the second and third terminals increase and decrease in opposite directions. , 1st diversion carp The electrically connected in parallel with the 1
One terminal of the first vertical deflection coil is connected to a terminal of the first vertical deflection coil opposite to the second vertical deflection coil, and is electrically connected in parallel with the first shunt coil. The other terminal of the capacitor is connected to the first terminal of the variable resistor, and one terminal of a second capacitor electrically connected in parallel with the second shunt coil is connected to the first terminal of the first capacitor. The other terminal of a second capacitor connected to a terminal of the second vertical deflection coil on the opposite side of the vertical deflection coil and electrically connected in parallel with the second shunt coil is connected to a terminal of the variable resistor. The variable resistor is connected to the third terminal, and the second terminal of the variable resistor is connected to a common connection terminal of the first and second vertical deflection coils.

In the vertical deflection device of the present invention, the resistor conventionally used for shunting the current flowing through the first and second vertical deflection coils is changed to a coil and a capacitor which are electrically connected in parallel. Even when the frequency of the parabolic upper / lower pincushion distortion correction current, which is the horizontal deflection period, is high, the upper / lower pincushion distortion correction can be performed sufficiently efficiently without affecting the asymmetric vertical misconvergence correction.

[0026]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a circuit diagram showing an example of a vertical deflection device according to the present invention. In the figure, the same elements as those in FIG. 2 and the like are denoted by the same reference numerals. This vertical deflection device corrects asymmetric vertical misconvergence by adjusting the current flowing through the first and second vertical deflection coils 106 and 108, as in the related art. The first and second vertical deflection coils 106 and 108 are mounted on the neck portion of the color cathode ray tube at the same position as in the related art and in the same state.

As shown in FIG. 1, the vertical deflection device comprises first and second shunt coils 4 and 6 and a first capacitor 8 electrically connected in parallel to the first shunt coil 4.
A second capacitor 10 electrically connected in parallel to the second shunt coil 6; and a first to third terminal 12
4, 128, 126 and the first and second terminals 12
4, 128 and the second and third terminals 128,
And a variable resistor 122 whose resistance value increases and decreases in the opposite direction.

One terminal of the first capacitor 8 electrically connected in parallel with the first shunt coil 4 is connected to the first vertical deflection coil 106 on the opposite side of the second vertical deflection coil 108. Terminal, and the first shunt coil 4
The other terminal of the first capacitor 8 electrically connected in parallel with the first terminal 1 of the variable resistor 122
24, and one terminal of the second capacitor 10 electrically connected in parallel with the second shunt coil 6
The other end of the second capacitor 10 connected to a terminal of the second vertical deflection coil 108 on the opposite side of the first vertical deflection coil 106 and electrically connected in parallel with the second shunt coil 6 Is connected to the third terminal 126 of the variable resistor 122, and the second terminal 128 of the variable resistor 122 is connected to a common connection terminal of the first and second vertical deflection coils 106 and 108. It is connected.

Hereinafter, in this vertical deflection apparatus, when the cycle of the horizontal deflection current is high, the relative value of the upper and lower pincushion distortion correction current is calculated specifically, and the efficiency of the upper and lower pincushion distortion correction current is calculated. It shows that is improved. Also in this vertical deflection device, the vertical deflection current shown in FIG.
Hz, and the frequency of the parabolic upper and lower pincushion distortion correction current that is the horizontal deflection cycle is, for example, 33.75 kHz.
And

The inductances L1 and L2 of the first and second vertical deflection coils 106 and 108 are both set to 2.
1 mH, first and second vertical deflection coils 106, 10
8, the resistance values RL1 and RL2 are both 3.5Ω, the inductances L3 and L4 of the first and second shunt coils 4 and 6 are both 3 mH, and the resistance values RL3 and RL4 of the first and second shunt coils 4, 6 Are 5Ω, the capacitance of the first and second capacitors C1 and C2 is 7420 pF, and the resistance value VR0 between the first and third terminals 124 and 126 of the variable resistor 122 is 200Ω. The slider of the variable resistor 122 is located at the midpoint between the first terminal 124 and the second terminal 126, and the first and second terminals 124, 12
The resistance value VR1 between 8 and 100 is 100Ω, and the resistance value VR2 between the second and third terminals 128 and 126 is 100Ω.

At this time, the combined impedance ZL of the capacitor 8 electrically connected in parallel with the first shunt coil 4
3C1 is as follows.

[0032]

(Equation 4)

Here, ω is 2πf, and the value of f is 33.75 kHz in this case. At this time, the frequency f
FIG. 4 shows a change in the value of the combined impedance ZL3C1 with respect to. As can be seen from FIG. 4, the vertical deflection current having a low frequency has the same resistance value as that of the conventional circuit, and therefore does not affect the asymmetric vertical misconvergence correction. The current flowing through the first horizontal deflection coil 106 and the combined current flowing through the capacitor 8 electrically connected in parallel with the first shunting coil 4 are proportional to the impedance ratio. , IL3C1,

[0034]

(Equation 5)

## EQU1 ## Accordingly, the ratio I of the current flowing through the first vertical deflection coil 106 to the combined current flowing through the capacitor 8 electrically connected in parallel with the first shunt coil 4 is shown.
L1 / IL3C1 has the following values.

[0036]

(Equation 6)

Also, the ratio of the current flowing through the second vertical deflection coil 108 to the combined current flowing through the capacitor 10 electrically connected in parallel with the second shunting coil 6 is determined because the circuit is symmetric. The ratio is the same as the ratio of the current flowing through one vertical deflection coil 106 to the combined current flowing through the capacitor 8 electrically connected in parallel with the first shunt coil 4. Since the impedance of the first horizontal deflection coil 106 was calculated by [Equation 1], that value was used here.

As described above, the asymmetric vertical misconvergence correction can be performed on the vertical deflection current component in the same manner as in the related art, and the parabolic upper and lower pincushion distortion correction current component having the horizontal deflection period can be corrected. The current can flow through the first and second vertical deflection coils 106 and 108 without attenuation, and the relative ratio of the correction current can be greatly improved as compared with 1 / 4.1 times the conventional value.

As a result, even when the frequency of the horizontal deflection current is high, the current for the upper and lower pincushion distortion correction using the parabolic current of the horizontal deflection period is not attenuated by the asymmetric vertical misconvergence correction circuit, and the vertical deflection coil is not attenuated. The upper and lower pincushion distortion can be sufficiently corrected without affecting the asymmetric vertical misconvergence correction.

When the horizontal deflection frequency changes, the frequency of the parabolic waveform of the pincushion distortion correction current also changes, so that the first and second capacitors C1, C
It is also necessary to change the capacity of No. 2 according to the frequency. Therefore, as shown in FIG. 6, a changeover switch is attached to the first and second capacitors C1 and C2 of the vertical deflection circuit shown in FIG. 1, and the first and second capacitors C1 and C2 are attached in parallel via the switches. By switching between the third and fourth capacitors C3 and C4, it is possible to cope with a change in frequency.

[0041]

As described above, in the vertical deflection apparatus of the present invention, the resistors conventionally used to shunt the current flowing through the first and second vertical deflection coils are electrically connected in parallel. Even if the frequency of the parabolic upper and lower pincushion distortion correction current, which is the horizontal deflection period, is high, the upper and lower pincushion distortion correction can be performed sufficiently efficiently without affecting the asymmetric vertical misconvergence correction. Can be.

As a result, even when the frequency of the horizontal deflection current is high, the current for upper and lower pincushion distortion correction using the parabolic current of the horizontal deflection cycle is not attenuated by the asymmetric vertical misconvergence correction circuit, and the first and second pincushion distortion correction circuits are not attenuated. The current can flow to the second vertical deflection coil, and sufficient upper and lower pincushion distortion correction can be performed without affecting the asymmetric vertical misconvergence correction. Also, the change of the horizontal frequency can be dealt with by switching the capacitor.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an example of a vertical deflection device according to the present invention.

FIG. 2 is a circuit diagram showing a conventional vertical deflection circuit.

FIG. 3A is an explanatory diagram showing a magnetic field when a current flowing through a first vertical deflection coil is larger. FIG. 3B is an explanatory diagram showing a magnetic field when a current flowing through a second vertical deflection coil is larger.

FIG. 4 is a diagram showing a combined resistance value of a shunt coil and a capacitor mounted in parallel with the shunt coil with respect to a change in frequency.

FIG. 5 is a waveform diagram showing a waveform of a current flowing through a vertical deflection coil.

FIG. 6 is a diagram showing an example of a vertical deflection device having a capacitor changeover switch corresponding to a change in the horizontal deflection frequency f.

[Description of Signs] 2 Vertical deflection device 4 First shunt coil 6 Second shunt coil 8 First capacitor 10 Second capacitor 12 Capacitor changeover switch 14 Capacitor changeover switch 16 Third capacitor 18 Fourth capacitor 106 First vertical deflection coil 108 Second vertical deflection coil 110 Neck 112 Electron beam 114 Electron beam 116 Electron beam 118 Resistor 120 Resistor 122 Variable resistor 124 First terminal 126 Third terminal 128 Second terminal 130 Magnetic field 132 Magnetic field 134 Magnetic field 136 Magnetic field

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C042 FG21 FG22 FH01 5C060 BE02 BE07 CD01 CD03 CE03 CF03 CG03 HA03 HA07 HB07 JA02 5C068 AA17 BA02 BA12 BA16 BA23 CC05 JB07 KA06

Claims (2)

[Claims] 1. A color cathode ray tube which is mounted on a color cathode ray tube as a deflecting device for performing a raster scan of an electron beam, is arranged with a plurality of electron beams emitted from an electron gun of the color cathode ray tube, and is electrically connected in series. A vertical deflection device that includes a first and a second vertical deflection coil, wherein the first and the second vertical deflection coils generate a magnetic field for performing vertical scanning; A first capacitor electrically connected in parallel with the coil;
A second electrically connected in parallel with the second shunt coil
And a variable resistor having three terminals,
A variable resistor in which the resistance between the first and second terminals of the variable resistor and the resistance between the second and third terminals of the variable resistor increase and decrease in opposite directions; One terminal of a first capacitor electrically connected in parallel with the shunt coil is connected to a terminal of the first vertical deflection coil opposite to the second vertical deflection coil, and the first capacitor is connected to the first capacitor. The other terminal of the first capacitor electrically connected in parallel with the shunt coil is connected to the first terminal of the variable resistor, and electrically connected in parallel with the second shunt coil. One terminal of the second capacitor is connected to a terminal of the second vertical deflection coil opposite to the first vertical deflection coil, and is electrically connected in parallel with the second shunt coil. The other terminal of the capacitor 2 is Serial connected to the third terminal, the second terminal of the variable resistor is connected to the common connection terminals of the first and second vertical deflection coils, it vertical deflection apparatus according to claim. 2. The apparatus according to claim 1, wherein the first and second capacitors have switches that can be switched to third and fourth capacitors, respectively, which are electrically connected in parallel to the first and second capacitors, respectively. The vertical deflection device according to claim 1, wherein: