JP3223608B2 - Convergence correction device and color cathode ray tube using the correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a convergence correction device suitable for a color cathode ray tube and a color cathode ray tube using the correction device.

[0002]

2. Description of the Related Art For example, in a color cathode ray tube in which three electron beams B, G, and R are arranged in-line, even if the convergence is made at the center of the screen, an overconvergence error occurs on the left and right sides (horizontal direction) of the screen. Convergence (hereinafter simply referred to as miscon). In order to correct this misconversion, a convergence yoke wound with a coil is usually arranged behind the deflection yoke. A parabolic magnetic field synchronized with the horizontal deflection frequency is generated from the coil, and the magnetic field causes the electron beams B and R on both sides to be slightly deflected to both sides and spread.

FIG. 4 shows the configuration of such a conventional convergence correction device. This technique is disclosed in Japanese Patent Application Laid-Open No. Hei 3-71538 previously proposed by the present applicant.

This convergence correction device is provided with a funnel section and a neck section of a cathode ray tube (CRT) 1 having B, G, R cathodes for generating three electron beams B, G, R arranged in-line. It has a pair of convergence yokes 2 and 3 disposed therebetween.

On the legs of the convergence yokes 2 and 3,
Each of the first convergence correction coils 4 (4a, 4a,
4b, 4c, 4d) and the second convergence correction coil 5 (5a, 5b, 5c, 5d) are wound in opposite directions. Here, the first convergence correction coil 4
Inductance value L ₁ and the inductance value L ₂ of the second convergence correction coil 4, equal (L ₁ =
L ₂ = L). Further, the respective inductance values of the first respective convergence correction coils 4a to 4d and the second respective convergence correction coils 5a to 5d
The respective inductance values of d are all equal. Further, the first convergence correction coil 4
Is connected to an external resistor 7 having a resistance value R.

In the convergence correction device having the above-described configuration, the first deflection coil 4 and the second deflection coil 5 are supplied with a horizontal deflection current i _H which is a sawtooth current.

Therefore, the voltage of the horizontal deflection current i _H is set to V
Then, the current i ₁ flowing through the first convergence correction coil 4 and the current i 2 flowing through the second convergence correction coil 5 are expressed as Equations ₁ and ₂ , respectively.

[0008]

(Equation 1)

[0009]

(Equation 2)

The convergence yoke 2 by the current i ₁
Assuming that the magnetic field in the magnetic field 3 is φ ₁ and the magnetic field due to the current i ₂ is φ ₂ , these magnetic fields are generated in mutually opposite directions. Therefore, the combined magnetic field φ _S generated in the convergence yokes 2 and 3 is , Φ _S = φ ₁ −φ ₂ = L ₁ i ₁ −L ₂ i ₂ .

Therefore, the synthetic magnetic field φ _S is given by
From Equation 3

[0012]

(Equation 3)

In equation (3), the current i ₁ has a waveform similar to the horizontal deflection current i _H and has a substantially saw-tooth waveform, so that its integral value changes in a parabolic manner. That is, the synthetic magnetic field φ _S is a magnetic field that changes in a parabolic manner,
Due to this magnetic field, the electron beams B and G are slightly deflected in the direction of the arrow, respectively, so that misconducting in the horizontal direction can be improved.

[0014]

In the above-described conventional convergence correction device and the color CRT using the correction device, as can be seen from Expression 3, the combined magnetic field φ
_In order to change the amplitude of _S , the resistance value R of the external fixed resistor 7 is an essential component.

However, this fixed resistor 7 has
Since the current corresponding to the horizontal deflection current i _H flows,
A power capacity of 0 W or more is required.
Four cement resistors or metal oxide film resistors of about 0 W are required, which causes a problem that the substrate area becomes large and mounting is difficult. That is, the number of parts increases and the number of manufacturing steps increases. In addition, the resistor 7
However, since the correction waveform changes due to the variation in the resistance value and the correction amount changes, there is a problem that a resistor having a high resistance value must be used.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a convergence correction device capable of omitting an external fixed resistor and a color CRT using the correction device. And

[0017]

The convergence correction device according to the present invention is, for example, as shown in FIG. 1, a convergence correction device for supplying a correction magnetic field for deflecting an electron beam in a horizontal direction to a cathode ray tube. , 3 and the convergence yokes 2, 3 are wound so that the directions of magnetization of the convergence yokes 2, 3 are opposite to each other, and the sawtooth currents i ₁ , i ₂ are supplied. 1st and 2nd convergence correction coils 2
4 and 25, wherein the internal resistance values r ₁ and r _{2 of} the first and second convergence correction coils 24 and 25 are different from each other. A color cathode ray tube according to the present invention is a color cathode ray tube having a convergence correction device for generating a correction magnetic field for deflecting an electron beam in a horizontal direction so that the directions of magnetization of the convergence yokes 2 and 3 are opposite to each other. The internal resistance values r ₁ and r _{2 of the} wound first and second convergence correction coils 24 and 25, respectively.
Is a color cathode ray tube having a convergence device 16 different from each other.

[0018]

According to the present invention, the internal resistance values r ₁ and r _{2 of} the first and second convergence correction coils 24 and 25 are set to different values. Therefore, the resultant magnetic field φ _S = φ ₁ −
φ ₂ becomes a magnetic field proportional to the difference | r ₁ −r ₂ | of the internal resistance values. Therefore, even without an external fixed resistor, a magnetic field that changes in a parabolic manner can be generated, and misconvergence in the horizontal direction can be improved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the convergence correction device of the present invention will be described below with reference to the drawings. In the drawings referred to below, the components corresponding to those shown in FIG. 4 are denoted by the same reference numerals.

FIG. 2 shows a cathode ray tube device to which the convergence correction device according to the present embodiment is applied.

This cathode ray tube device is a cathode ray tube (CRT) 1 using a so-called single electron gun three beam system in which three cathode electrodes are arranged inline in one grid electrode.
have.

A deflection yoke assembly 11 is disposed between the funnel and the neck of the CRT 1. A horizontal deflection coil 13 is wound inside the front cover 12 of the deflection yoke assembly 11, and the front cover 12 and the rear cover 1
A vertical deflection coil 15 is wound between the four. A convergence correction device 16 is arranged behind the vertical deflection coil 15.

FIG. 1 is a schematic diagram showing a detailed configuration of the convergence correction device 16.

The convergence correction device 16 is disposed between a funnel portion and a neck portion of the CRT 1 having B, G, and R cathodes for generating three electron beams B, G, and R arranged in-line. And a pair of convergence yokes 2 and 3.

On the legs of the convergence yokes 2 and 3,
A first convergence correction coil 24 having four convergence correction coils 24a, 24b, 24c, 24d connected in series, and four convergence correction coils 25a, 25b, 25c, 2 connected in series, respectively.
The second convergence correction coil 25 having 5d is wound in the opposite direction.

Convergence correction coils 24a, 24
b, 24c, and 24d each have a configuration in which an insulated wire having a wire diameter of φ0.21 is wound five times (5T) each.
On the other hand, the convergence correction coils 25a, 25b, 25
Each of c and 25d has a configuration in which two stranded wires of an insulated wire having a wire diameter of φ0.5 are wound five times each in the opposite direction.
The reason why the two stranded wires are used is to make the winding easier by using a thin wire.

Therefore, the inductance values L ₁ and L ₂ of the first convergence correction coil 24 and the second convergence correction coil 25 are substantially equal. Further, the internal resistance of the first convergence correction coil 24 is set to the value r ₁ , and the second convergence correction coil 25
Assuming that the internal resistance value is r ₂ , r ₁ > r ₂ . Considering that the resistance value is inversely proportional to the square of the wire diameter φ, in this embodiment, the resistance value ratio (r ₁ / r ₂ )
Is about 11 times (r ₁ / r ₂ ) = (1 / 0.21 ² ) ·
(0.5 ² +0.5 ² ) ≒ 11 .

FIG. 3 shows an equivalent circuit of a configuration in which the horizontal deflection coil 13 is connected to the convergence correction device 16 shown in FIG. That is, the same horizontal deflection current i _H is supplied to the convergence correction device 16 including the first and second convergence correction coils 24 and 25 and the horizontal deflection coil 13.

Next, the operation of the above embodiment will be described.

The horizontal deflection current i _H is supplied to the first convergence correction coil 24 and the second convergence correction coil 25.

Therefore, when the voltage generated at both ends of the convergence correction device 16 generated by the horizontal deflection current i _H is V (see FIG. 3), the current i ₁ flowing through the first convergence correction coil 24 and the second The current i ₂ flowing through the convergence correction coil 25 is expressed by Equations 4 and 5, respectively.

[0032]

(Equation 4)

[0033]

(Equation 5)

The convergence yoke 2 by the current i ₁
Assuming that the magnetic field in the magnetic field 3 is φ ₁ and the magnetic field due to the current i ₂ is φ ₂ , these magnetic fields are generated in mutually opposite directions. Therefore, the combined magnetic field φ _S generated in the convergence yokes 2 and 3 is , Φ _S = φ ₁ −φ ₂ = L ₁ i ₁ −L ₂ i ₂ .

Therefore, the synthetic magnetic field φ _S is expressed by the following equation (6).

[0036]

(Equation 6)

In Equation 6, the current i ₁ and the current i
₂ is a waveform similar to the horizontal deflection current i _H , and its current value is represented by the first and second convergence correction coils 2.
Since they are determined by the reactance values of 4, 25, they are almost equal. On the other hand, the resistance value ratio (r ₁ / r ₂ ) is about 11
When these are taken into account,
Is transformed into Equation 7.

(Equation 7)

Equation 7 is a formula similar to Equation 3 described above.
In equation (7), the current i ₁ has a waveform similar to the horizontal deflection current i _H and is substantially a sawtooth current waveform, so that the integrated value changes in a parabolic manner. In other words, the synthetic magnetic field φ _S is a magnetic field that changes in a parabolic manner, and this magnetic field finely deflects the electron beams B and G in the directions of the arrows, respectively, thereby improving horizontal misconduct.

As described above, according to the above-described embodiment, the internal resistance values of the first and second convergence correction coils 24 and 25 are different values r ₁ and r ₂ . Therefore, the resultant magnetic field φ _S is determined by the difference r ₂ − between the internal resistance values r ₁ and r _2.
The magnetic field becomes proportional to r ₁ . Therefore, even without an external fixed resistor, a magnetic field that changes in a parabolic manner can be generated, and misconvergence in the horizontal direction can be improved.

In this case, since the internal resistance difference r ₂ -r ₁ between the first and second convergence correction coils 24 and 25 is used, an external fixed resistor can be omitted. As a result, both the number of parts and the number of manufacturing steps can be reduced. In addition, since the number of heat-generating components is reduced, the reliability is improved. Further, since the error in the resistance value of the external fixed resistor is reduced, the variation in misconvergence is reduced, and the quality is stabilized.

The present invention is not limited to the above-described embodiment, but can adopt various configurations without departing from the gist of the present invention.

[0042]

As described above, according to the present invention,
The first and second convergence correction coils have different internal resistance values. For this reason, the combined magnetic field becomes a magnetic field proportional to the difference between the internal resistance values. Therefore, even without an external fixed resistor, it is possible to generate a magnetic field that changes in a parabolic manner, and it is possible to improve horizontal misconvergence.

In this case, since an external fixed resistor can be omitted, both the number of parts and the number of manufacturing steps can be reduced. Further, since the number of heat-generating components is reduced, the reliability of the device to which the present invention is applied is improved. Furthermore, since the resistance value error such as that of an externally fixed resistor is reduced, the variation in misconvergence in the device to which the present invention is applied is reduced, and the quality is stabilized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an embodiment of a convergence correction device according to the present invention.

FIG. 2 is a perspective view showing a configuration of a cathode ray tube device to which the device of FIG. 1 is applied.

FIG. 3 is a circuit diagram including an equivalent circuit of the device of FIG. 1;

FIG. 4 is a schematic diagram illustrating a configuration of a convergence correction device according to a conventional technique.

[Explanation of symbols]

1 CRT 2,3 convergence yoke 24 first convergence correction coil 25 second convergence correction coil i _H horizontal deflection current

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-71538 (JP, A) JP-A-3-91391 (JP, A) JP-A-4-63088 (JP, A) 208490 (JP, A) Japanese Utility Model Showa 60-32872 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 9/28 H01J 29/76

Claims (5)

(57) [Claims] 1. A convergence correction device for supplying a correction magnetic field for deflecting an electron beam in a horizontal direction to a cathode ray tube. Rolled up,
A convergence correction device comprising: first and second convergence correction coils to which a saw-tooth wave current is supplied, wherein the first and second convergence correction coils have different internal resistance values. 2. The convergence correction coil according to claim 1, wherein the first convergence correction coil is formed of one wire, and the second convergence correction coil is formed of two wires connected in parallel. 2. The convergence correction device according to 1. 3. The convergence correction device according to claim 1, wherein the cathode ray tube is a cathode ray tube having a single electron gun and three beams. 4. A color cathode ray tube having a convergence correction device for generating a correction magnetic field for deflecting an electron beam in a horizontal direction, wherein the first convergence yoke is wound so that the directions of magnetization are opposite to each other. And a convergence device in which the internal resistance values of the second convergence correction coil are different from each other. 5. The convergence correction device according to claim 1, wherein the first convergence correction coil is constituted by one electric wire, and the second convergence correction coil is constituted by an electric wire in which two electric wires are connected in parallel. 5. A color cathode ray tube according to claim 4, wherein: