JPH0698340A - Landing correction device - Google Patents

Abstract

PURPOSE:To simplify the adjustment method for landing correction and to implement highly accurate landing correction. CONSTITUTION:A landing correction means of a correction coil pair made of two coils such as an X axis direction correction coil 7 and a Y axis direction correction coil 8 is arranged to a prescribed position around the circumferential part of a cathode ray tube. A magnetic field direction setting section 12 setting a magnetic field direction of a correction magnetic field generated by a landing correction means and a magnetic field strength adjustment section 13 adjusting the magnetic field strength are sequentially controlled in terms of algorithm by a control section 14 to make the direction of the earth magnetism coincident with the direction of an electron beam. Thus, simple landing correction with high accuracy using digital control is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a landing correction device for a color television receiver which prevents a reduction in color purity of a cathode ray tube caused by the influence of the earth's magnetism.

[0002]

2. Description of the Related Art Generally, in a color television receiver that deflects an electron beam and scans a phosphor to produce a display image, a landing position shift of the electron beam occurs due to the influence of the earth's magnetic field, and thus a display is generated. Luminance and chromaticity change on the image, causing deterioration of image quality. The correction of the deterioration of the image quality due to this mislanding is performed by using a correction coil and canceling the influence of the geomagnetism by the correction magnetic field.

A conventional landing correction device is disclosed, for example, in Japanese Patent Laid-Open No. 02-029187, "Beam landing correction device for color cathode ray tube". This JP-A-0
FIG. 6 shows a layout diagram of the landing correction coils of No. 2-029187 "color cathode ray tube beam landing correction device". In FIG. 6, 1 to 6 are landing correction coils. This landing correction device cancels the influence of the geomagnetism applied to the cathode ray tube by causing an appropriate correction current to flow through each correction circuit corresponding to the landing correction coil arranged as shown in FIG.

[0004]

However, in the above-mentioned configuration, when the adjuster performs the landing adjustment of a certain area on the display image of the television receiver, the correction coil and the other correction coil in the adjustment area are close to each other. Due to the influence of the correction magnetic field generated by other correction coils, it is not possible to make accurate landing adjustment by adjusting the adjustment current corresponding to each correction coil once, and the adjustment current is adjusted many times. However, the landing adjustment takes a very long time, and accurate correction cannot be performed. Further, in the correction coil configuration as shown in FIG. 6, the direction of the correction magnetic field cannot be controlled, so that it is not possible to deal with the geomagnetism in an arbitrary direction and there is a problem that a highly accurate landing correction cannot be performed.

In view of the above point, the present invention has an object to provide a landing correction device which is highly accurate and has a simplified adjustment procedure.

[0006]

In order to achieve the above object, a first invention of the present invention is to provide a correction coil for an x-axis direction (horizontal direction on a cathode ray tube surface) in a cathode ray tube display device,
Landing correction means, in which a plurality of coil pairs each including two correction coils in the y-axis direction (vertical direction on the surface of the cathode ray tube) are arranged at a predetermined position around the cathode ray tube, and a correction magnetic field generated by the landing correction means. And a magnetic field strength adjusting means for adjusting the magnetic field strength of the correction magnetic field.

A second invention is provided with a mislanding error detection means for detecting a mislanding in the correction area,
The landing correction device performs automatic landing correction by controlling the correction means in accordance with the output of the mislanding error detection means.

[0008]

In the landing correction device of the first aspect of the present invention having the above-mentioned structure, the correction is made by the landing correction means arranged in plural at a predetermined position around the cathode ray tube as a coil pair consisting of an x-axis direction correction coil and a y-axis direction correction coil. By controlling the magnetic field direction and the correction magnetic field strength algorithmically by the correction magnetic field direction setting means and the correction magnetic field strength adjusting means, adjustment of mislanding due to geomagnetism on the display screen can be simplified and high-precision partial correction is possible. Becomes

According to the second aspect of the invention, the mislanding error on the display image of the television receiver is detected by the mislanding error detecting means, and the optimum direction and intensity of the correction magnetic field are detected according to the error amount. It is possible to perform highly accurate automatic landing correction by supplying the data to the landing correction means capable of independently changing the direction and strength of the correction magnetic field.

[0010]

1 is a block diagram of a landing correction device according to a first embodiment of the present invention. As its constituent elements, 7 is an x-axis direction (horizontal direction on the cathode ray tube surface) correction coil, and 8 is a y-axis direction (vertical direction on the cathode ray tube surface) correction coil. Reference numerals 9 and 10 denote amplification units for supplying correction currents to these coils, and 11 denotes a gain control unit for adjusting the gains of the amplification units 9 and 10 and constitute a landing correction unit and its driving unit. Also, 1
Reference numeral 2 denotes a correction magnetic field direction setting unit for setting the magnetic field direction of the landing correction magnetic field by the combined vector formed by the two coils of the x-axis direction correction coil 7 and the y-axis direction correction coil 8, 13
Is a correction magnetic field strength adjusting unit for the landing correction magnetic field, and 14 is a control unit for controlling the correction magnetic field direction setting unit 12 and the correction magnetic field strength adjusting unit 13. The x-axis direction correction coil 7 and the y-axis direction correction coil 8 are, as shown in FIG.
7n and the y-axis direction correction coils 8a to 8n are arranged in the peripheral portion of the cathode ray tube so that they are perpendicular to each other. The operation of the landing correction apparatus of the first embodiment constructed as above will be described below.

First, in this embodiment, the x-axis direction correction coil 7 and the y-axis direction correction coil 8 are used as the landing correction coil.
The effect of using as one correction coil pair will be described with reference to FIG. In FIG. 3, 17 is a geomagnetic vector causing mislanding, and 18 is an electron beam.
Shows the vector of the mu. Mislanding is an electron beam in which the Lorentz force is applied to the electron beam by the geomagnetism.
It occurs when the landing position of the mums changes. In order to eliminate this mislanding, the vector of the geomagnetism is set to 0 completely, or the directions of the geomagnetic vector 17 and the electron beam vector 18 are made to coincide with each other so that the angle formed by these vectors is set to 0 and the electron beam's angle is set to 0. There are two possible ways to cancel the received force. In order to realize the former method of completely canceling the earth's magnetism, it is necessary to use three-direction correction coils, and it is found that this method is extremely difficult considering the structure of the cathode ray tube, and the latter method is more preferable. More practical. Further details of this method are as follows.

The force that causes mislanding, that is, the magnitude of the Lorentz force, depends on the geomagnetic vector 17 and the electron beam.
If the angle formed by the vector 18 is θ, it depends on sin θ. That is, if the directions of the geomagnetism and the electron beam are made to coincide with each other, the Lorentz force becomes 0, and the influence of mislanding due to the geomagnetism can be canceled. That is, the magnitude and direction of the xy plane component of the geomagnetism are converted into an appropriate vector by a landing correction coil that generates a correction magnetic field in two directions of the x-axis direction and the y-axis direction, and the vector on the xy plane and the z-axis of the geomagnetism are converted. By controlling the direction of the combined vector with the direction component (tube surface direction component) to match the direction of the electron beam, it is possible to perform highly accurate landing correction.

A method of controlling the correction coil of the present invention in which the correction coil pair of the x-axis direction correction coil 7 and the y-axis direction correction coil 8 described above is used as a landing correction coil will be described with reference to FIG. In FIG. 4, 19 is the geomagnetic xy plane component,
Reference numeral 20 is a correction magnetic field vector created by the landing correction coil, 21 is a composite vector of the correction magnetic field and the geomagnetism by the landing correction coil, and 22 is a target value of a vector to match the magnetic field direction and the magnetic field strength of the composite vector 21. That is, if the combined vector 21 of the correction magnetic field vector 20 and the geomagnetic vector 19 matches the target value 22 of this vector, the z-direction component (tube surface direction component) of the geomagnetism and the target value 22.
The combined vector of and coincides with the direction of the electron beam, and the effect of mislanding due to geomagnetism can be canceled.

The control procedure is as follows.
First, the correction magnetic field direction setting unit 12 generates correction magnetic field direction setting data A34 and B35, and these data are amplified by the amplification units 9 and 1.
The gain control unit 11 adjusts the gains of the amplification units 9 and 10 by the gain control data A36 and B37 so that the gain becomes zero. Therefore, the correction magnetic field strength adjustment unit 13 generates correction magnetic field strength adjustment data and supplies it to the amplifiers 9 and 10, whereby the ratio of the correction currents flowing through the x-axis direction correction coil 7 and the y-axis direction correction coil 8 becomes constant. The correction magnetic field strength produced by the landing correction coil can be changed while keeping the direction of the landing correction magnetic field constant. That is, by making the correction magnetic field direction constant and varying the strength of the correction magnetic field, it is possible to determine whether or not to match the vector target value 22 in the correction magnetic field direction. From this, by controlling the magnetic field direction setting and the magnetic field strength setting by the control unit 14 to sequentially change the direction and strength of the landing correction magnetic field, and to judge the landing state on the color television receiver display screen at any time, It is possible to determine the optimum correction magnetic field algorithmically.

As described above, the x-axis direction correction coil 7,
The correction coil pair of the y-axis direction correction coil 8 is arranged as a landing correction coil in the peripheral portion of the cathode ray tube as shown in FIG. 2, and the current flowing through the landing correction coil is controlled as in the present invention, thereby performing digital control. It is possible to easily and accurately adjust the landing.

FIG. 5 shows a block diagram of a landing correction device and a landing correction coil according to a second embodiment of the present invention. As shown in FIG. 5A, as its constituent elements, 23 is a display section for displaying image receiving information on a color television receiver, 24 is a correction area designating section for designating an area for performing landing correction, and 25 is a correction area. Designation part 2
A test signal generating section for generating a test signal corresponding to 4;
Reference numeral 26 is a mislanding error detection unit for detecting a mislanding error from the test signal displayed on the display image of the television receiver, and 27 is a converter for converting the mislanding error data, which is an analog value, into digital data. A / D
And 28 are data from the mislanding error detection unit 26.
A correction data generating unit for generating correction magnetic field data corresponding to the correction region designating unit 24 based on the data, 29 is a memory unit for storing the correction magnetic field data corresponding to the correction region, 30 Is a D / A unit for converting the correction magnetic field data into an analog value, 31
Is a drive unit for driving the landing correction unit 32 based on the correction magnetic field data. Further, in FIG. 5B, reference numeral 33 is a landing correction coil composed of two coils, that is, an x-axis direction correction coil and a y-axis direction correction coil similar to those of the first embodiment.

The operation of the landing correction apparatus of the second embodiment constructed as above will be described below.
As described in the first embodiment, the landing correction coil 33 can independently control the direction and strength of the correction magnetic field. When performing the landing adjustment on the display screen of the display unit 23, the correction region designating unit 24 first designates the region in which the landing correction is to be performed. In response to the output of the correction area designating section 24, the test signal generating section 25 displays a test signal for performing landing adjustment on the correction area on the display surface of the display section 23. With this test signal, the mislanding error detection unit 26 detects a mislanding error in the correction area. The error data of this mislanding error detection unit 26 is supplied to the correction data generation unit 28 as digital data by the A / D unit 27. Based on this error data, the correction data generating unit 28 generates the optimum magnetic field strength and magnetic field direction data for correction. The memory unit 29 stores this correction data, and supplies the correction data to the driving unit 31 through the D / A unit 30 at any time, and the driving unit 31 uses the correction data to the peripheral portion of the cathode ray tube. The arranged landing correction unit 32 is driven.

As described above, by constructing the landing correction device as in the second embodiment of the present invention, highly accurate automatic landing correction can be performed. In the present embodiment, the landing correction coil is arranged in the peripheral portion of the cathode ray tube for explanation, but it is needless to say that it may be arranged in another place.

In this embodiment, the shape of the landing coil has been described as a rectangle, but it goes without saying that other coil shapes that can independently control the direction and strength of the correction magnetic field are also effective. Further, it goes without saying that the second embodiment can also be constructed by an analog circuit.

[0020]

As is apparent from the above description, according to the first aspect of the invention, the coil pair consisting of the two coils of the x-axis direction correction coil and the y-axis direction correction coil is used as the landing correction coil. It is possible to independently control the direction of the correction magnetic field generated by the landing correction coil. By sequentially controlling the magnetic field direction and magnetic field strength of the correction magnetic field created by this landing correction coil with the control terminal, it is possible to perform highly accurate landing correction with algorithmic control. It becomes possible to perform highly accurate landing adjustment.

Further, as in the second aspect of the invention, a mislanding error on the image displayed on the television receiver is detected, and the data of the direction and strength of the optimum correction magnetic field are detected in the x-axis direction correction coil in accordance with the error amount. By supplying to the landing correction coil composed of the y-axis direction correction coil, highly accurate automatic landing correction can be performed, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram of a landing correction device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing an arrangement of landing correction coils in the embodiment.

FIG. 3 is a vector diagram for explaining the operation of the embodiment.

FIG. 4 is a vector diagram illustrating a method for controlling a correction current flowing in the landing correction coil according to the embodiment.

5A is a block diagram of a landing correction device according to a second embodiment of the present invention, and FIG. 5B is a perspective view showing an arrangement of landing correction coils of the same embodiment.

FIG. 6 is a perspective view showing an arrangement of landing correction coils in a conventional landing correction device.

[Explanation of symbols]

 7 x-axis direction correction coil 8 y-axis direction correction coil 9 and 10 amplification part 11 gain control part 12 correction magnetic field direction setting part 13 correction magnetic field strength adjustment part 14 control part

Claims (4)

[Claims] 1. A landing correction means comprising a plurality of coil pairs each having two correction coils whose correction magnetic field axes are orthogonal to each other, a driving means for driving the landing correction means, and the landing correction means. A correction magnetic field direction setting means for setting the magnetic field direction of the resulting correction magnetic field, a correction magnetic field strength adjusting means for varying the correction magnetic field strength without substantially affecting the correction magnetic field direction, the correction magnetic field direction setting means, and the correction A landing correction device comprising control means for controlling the magnetic field strength adjusting means. 2. The landing correction apparatus according to claim 1, wherein the control means sequentially performs two controls, that is, a correction magnetic field direction setting and a correction magnetic field strength adjustment. 3. Display means for displaying image reception information of a color television receiver, landing correction means for performing landing correction, correction area designation means for designating a correction area for landing correction, and the correction area designation means. A test signal generating means for displaying a test signal on the display screen of the display means in accordance with the output of, and a mislanding error detecting means for detecting a mislanding in the correction area,
Correction magnetic field data generating means for generating correction magnetic field data corresponding to the correction area specified by the correction area specifying means according to the output of the mislanding error detecting means, and the correction magnetic field data generating means. 2. A landing correction device comprising: a memory unit for storing the correction magnetic field data generated by the above; and a driving unit for driving the landing correction unit according to the output of the memory unit. 4. The correction magnetic field data generating means generates data of the magnetic field direction and the magnetic field strength of the correction magnetic field according to the amount of mislanding error in the landing correction area. The landing correction device described.