JP3000882B2 - Evaluation apparatus and evaluation method for deflection yoke - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for evaluating a deflection yoke of a cathode ray tube, and more particularly, to a deflection cathode yoke incorporated in a color cathode ray tube and to evaluate deflection magnetic field balance of the deflection yoke in advance in an ITC process. The present invention relates to a deflection yoke evaluation apparatus and method suitable for selecting a deflection yoke suitable for the characteristics of a cathode ray tube and simplifying an ITC operation.

[0002]

2. Description of the Related Art In general, a color cathode ray tube deflects three electron beams of R, G, and B emitted from an electron gun by horizontal and vertical deflection magnetic fields of a deflection yoke mounted outside a bulb to produce a large number of electron beams. An image is displayed by causing a predetermined phosphor layer on the phosphor screen to emit light by performing horizontal and vertical scanning through a shadow mask having a through hole. Normal,
Due to variations in the components such as the electron gun and phosphor screen of the color cathode ray tube and in the assembly process, and variations in the manufacturing process such as the winding distribution of the deflection yoke, a simple combination of the color cathode ray tube and the deflection yoke is not sufficient. Since a display device of image quality cannot be obtained, an ITC that adjusts the deflection magnetic field distribution by, for example, adding a magnet or ferrite to the outside of the deflection yoke for each combination of the color cathode ray tube and the deflection yoke is usually used. A process is provided.

However, in this ITC process, since there are fluctuation factors in both the color cathode ray tube and the deflection yoke, the deflection yoke is attached to the color cathode ray tube, and the mounting position is displayed while displaying a test pattern for each set on a screen. Is adjusted, or a magnet or ferrite is attached to an optimum location outside the deflection yoke based on the empirical knowledge of the operator. Therefore, this ITC work takes time even for a skilled worker, and requires man-hours. Therefore, if the deflection magnetic field distribution of the deflection yoke is measured in advance and selected or adjusted so as to match the characteristics of the color cathode ray tube, this IT
C operation becomes easy. On the other hand, in a conventional deflection yoke magnetic field measuring device, as shown in FIG. 3, the magnetic sensor 1 is moved and arranged in the X, Y, and Z directions of the internal space of the deflection yoke 2 by a drive device 3 controlled by a computer. A rated deflection current is supplied to the horizontal deflection coil 2a and the vertical deflection coil 2b of the deflection yoke 2 from the deflection power supply 4, the magnetic field intensity at each position is measured, and the data processing unit 5 performs arithmetic processing by a computer to calculate the magnetic field. It was a method to obtain the distribution.

[0004]

Therefore, the above-mentioned magnetic field measuring device is a large-scale device, and the device is expensive and it takes a long time for measurement. There was a problem that it could not be applied to measurement and could not be used for prior evaluation of the ITC work described above. An object of the present invention is to solve the above problems by measuring the balance of voltages induced in at least one pair of diametrically arranged detection coils on an insulator fitted inside a deflection yoke, thereby enabling ITC work. An object of the present invention is to provide a deflection yoke evaluation apparatus and an evaluation method having a simple configuration suitable for preliminary evaluation.

[0005]

According to the present invention, there is provided a deflection yoke having a horizontal deflection coil and a vertical deflection coil and opened in a trumpet shape toward a front end, and a diametrically extending insulator provided inside the deflection yoke. A magnetic field detection unit having at least a pair of detection coils arranged side by side; a deflection power supply for supplying a deflection current to the horizontal deflection coil and the vertical deflection coil; and an evaluation unit for evaluating a balance between voltages induced in the pair of detection coils. The present invention provides a deflection yoke evaluation device constituted by:
In addition, the magnetic field detecting section has a pair of detecting coils and has a mechanism for rotating while being fitted in the deflection yoke, or the magnetic field detecting section has a configuration in which a plurality of pairs of detecting coils are radially arranged. desirable. Further, a rated deflection current is applied to each of the horizontal deflection coil and the vertical deflection coil, and a difference between voltages induced in at least one pair of detection coils arranged in a diameter direction on an insulator fitted inside the deflection yoke is obtained. And a deflection yoke evaluation method for evaluating the deflection yoke based on the difference of In addition, a constant current sine wave alternating current is superimposed on the rated deflection current and applied to the horizontal deflection coil and the vertical deflection coil, respectively, and the current is applied to at least one pair of detection coils arranged in a diameter direction on an insulator fitted inside the deflection yoke. Find the difference between the induced voltages, evaluate the deflection yoke with the difference between the voltages,
A constant current sine wave alternating current is applied to the horizontal deflection coil and the vertical deflection coil, and a difference between voltages induced in at least one pair of detection coils arranged in a diameter direction on an insulator fitted inside the deflection yoke is obtained. It is desirable to evaluate the deflection yoke by the difference of

[0006]

According to the above construction, the deflection of the deflection yoke in the direction perpendicular to the detection coil is obtained by finding the balance of the voltages induced in the pair of detection coils arranged in the diameter direction on the insulator fitted inside the deflection yoke. Since it is possible to evaluate whether the distribution of the magnetic field is balanced, the pair of detection coils are fitted inside the deflection yoke and rotated to measure the balance of the induced voltage, or a number of pairs of detection coils are radially arranged. By measuring the balance of the voltages induced in each pair of detection coils, the balance of the distribution of the deflection magnetic field in all deflection directions can be evaluated. Therefore, the deflection yoke evaluation apparatus having a simple configuration is used to evaluate all the deflection yokes before performing the ITC work, and to select and use the deflection yoke in which the balance of the deflection magnetic field is within an allowable range. Becomes easier. In addition, a constant deflection sine wave alternating current is superimposed on the rated deflection current and a constant deflection sinusoidal alternating current is applied to the horizontal deflection coil and the vertical deflection coil, respectively, and the deflection yoke is induced by a pair of detection coils. When the voltage difference is obtained and the deflection yoke is evaluated based on the voltage difference, the balance of the magnetic field distribution including the impedance and the transient characteristics of the deflection yoke at a frequency higher than the scanning frequency can be evaluated.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. The same parts as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted. As shown in FIG. 1, the deflection yoke evaluation device according to one embodiment of the present invention includes a deflection yoke 2 having a horizontal deflection coil 2a and a vertical deflection coil 2b, and opened in a trumpet shape toward a front end. The detection coils 7, 7 formed by winding a pair of enamel wires 10 times on one surface of a substantially trapezoidal insulating plate 6 made of a non-magnetic material such as plastic or glass and fitted inside the deflection yoke 2 are provided. An evaluation unit 9 for evaluating the balance of a deflection magnetic field composed of a deflection power supply 4 for supplying a rated deflection current to the deflection coil 2a and the vertical deflection coil 2b, and an oscilloscope 8 for inputting a voltage induced in the pair of detection coils 7, 7. It is composed of A method of evaluating a deflection yoke by the deflection yoke evaluation apparatus will be described by taking an actual evaluation of a deflection yoke for a cathode ray tube as an example. That is, first, the insulator plate 6 on which the pair of detection coils 7, 7 is formed is fitted inside the deflection yoke 2, and the detection coils 7, 7 are arranged so as to be arranged vertically to the horizontal deflection direction. Then, the deflection power supply 4 supplies a rated deflection current to the horizontal deflection coil 2a and the vertical deflection coil 2b of the deflection yoke 2, respectively. Then, when the voltages induced in the pair of detection coils 7 and 7 are input to the oscilloscope 8 of the evaluation unit 9, a straight line inclined at a constant angle corresponding to the balance of the vertical deflection magnetic field of the deflection yoke 2 is displayed.

Similarly, the detection coils 7, 7 are arranged by being rotated by 90 ° so as to be arranged perpendicularly to the vertical deflection direction, and the voltages induced in the detection coils 7, 7 are respectively applied to the oscilloscope 8 of the evaluation unit 9. When input, a straight line with a constant inclination angle is displayed corresponding to the balance of the vertical deflection magnetic field of the deflection yoke 2. If the inclination angle is within the specified range, the deflection yoke 2 is sent to the ITC process as a non-defective product, and convergence adjustment can be easily performed.

As shown in FIG. 2, the deflection yoke evaluating apparatus according to the second embodiment of the present invention comprises two pairs of detection coils, a pair of detection coils 10, 10 and another pair of detection coils 11, 10.
11 in the horizontal deflection direction and vertical deflection direction of the deflection yoke,
They are arranged orthogonally so as to be vertical. According to this embodiment, the balance between the horizontal and vertical deflection magnetic fields can be evaluated in the same manner as in the above-described embodiment. Moreover, the balance between the horizontal and vertical deflection magnetic fields can be evaluated at the same time without rotating the detection coils 10 and 11. Usually, by evaluating the balance between the orthogonal horizontal and vertical deflection magnetic fields as described above, a deflection yoke that facilitates the ITC process can be selected.

In another embodiment of the present invention, a deflection yoke is evaluated by superimposing a constant sine-wave alternating current on a rated deflection current on the horizontal deflection coil and the vertical deflection coil of the above-described evaluation apparatus. When a current is applied or a constant current sine wave alternating current is applied, a difference between voltages induced in the pair of detection coils is obtained, and the deflection yoke is evaluated based on the difference between the voltages. According to the evaluation method of this embodiment, the balance of the deflection magnetic field distribution of the deflection yoke at a frequency higher than the scanning frequency can be evaluated, so that the impedance and the transient characteristics of the deflection yoke can be evaluated.

The apparatus and method for evaluating a deflection yoke having a detection coil formed on one or two pairs of insulator plates for evaluating the balance between orthogonal horizontal and vertical deflection magnetic fields have been described above. The present invention is not limited to the above-described embodiment. If necessary, if the detection coils formed inside the substantially frustoconical insulator cone are rotated or arranged in multiple pairs, the balance of the deflection magnetic field and the vertical deflection magnetic field in various places can be obtained. Then, the degree of orthogonality of the horizontal deflection magnetic field can be evaluated.

[0012]

According to the present invention, the deflection yoke in the direction perpendicular to the detection coil is obtained by obtaining the balance of the voltages induced in the pair of detection coils arranged side by side in the diameter direction of the insulator fitted inside the deflection yoke. Can be evaluated whether the distribution of the deflection magnetic field is balanced by measuring the voltage balance induced while rotating the pair of detection coils inside the deflection yoke, and arranging multiple pairs of detection coils radially. By measuring the balance of the voltages induced in the respective pairs of detection coils, it is possible to evaluate the balance of the distribution of the deflection magnetic field in all deflection directions. Therefore, the deflection yoke evaluation apparatus having a simple configuration is used to evaluate all the deflection yokes in advance of the ITC work, and the deflection yoke whose deflection magnetic field balance is within an allowable range is selected and used. Becomes easier. Also, a constant current sine wave AC is superimposed on the rated deflection current and a constant current sine wave AC is applied to the horizontal deflection coil and the vertical deflection coil, respectively. When the voltage difference is obtained and the deflection yoke is evaluated based on the voltage difference, the balance of the magnetic field distribution including the impedance and the transient characteristics of the deflection yoke at a frequency higher than the scanning frequency can be evaluated.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a deflection yoke evaluation apparatus according to one embodiment of the present invention.

FIG. 2 is a perspective view of a main part of a deflection yoke evaluation apparatus according to another embodiment of the present invention.

FIG. 3 is a schematic perspective view of a conventional magnetic field measuring device for a deflection yoke.

[Explanation of symbols]

 Reference Signs List 2 deflection yoke 2a horizontal deflection coil 2b vertical deflection coil 4 deflection power supply 6 insulator plate (insulator) 7, 10, 11 detection coil 8 oscilloscope 9 evaluation unit

Claims (6)

(57) [Claims] 1. A deflection yoke in which a horizontal deflection coil and a vertical deflection coil are arranged in a trumpet shape toward a front end, and at least a pair of detection coils arranged in a diameter direction of an insulator fitted in the deflection yoke. A deflection yoke evaluation device, comprising: a magnetic field detection unit having a deflection power supply for supplying a deflection current to the horizontal deflection coil and the vertical deflection coil; and an evaluation unit for evaluating a balance between voltages induced in the pair of detection coils. 2. The deflection yoke evaluation device according to claim 1, further comprising a mechanism for rotating the magnetic field detection unit fitted inside the deflection yoke. 3. The deflection yoke evaluation apparatus according to claim 1, wherein said magnetic field detection section has a configuration in which a plurality of pairs of detection coils are radially arranged. 4. A rated deflection current is supplied to each of the horizontal deflection coil and the vertical deflection coil, and a difference between voltages induced in at least one pair of detection coils arranged in a diameter direction on an insulator fitted inside the deflection yoke is obtained. A deflection yoke evaluation method for evaluating the deflection yoke based on the voltage difference. 5. A horizontal deflection coil and a vertical deflection coil, each of which is energized by superimposing a constant sine wave alternating current on a rated deflection current, and at least a pair of diametrically arranged insulators fitted in a deflection yoke. A method for evaluating a deflection yoke in which a difference between voltages induced in a detection coil is obtained, and a deflection yoke is evaluated based on the difference between the voltages. 6. A difference between voltages induced in at least one pair of detection coils arranged in a diameter direction on an insulator fitted in a deflection yoke by applying a constant current sine wave alternating current to each of a horizontal deflection coil and a vertical deflection coil. And a deflection yoke evaluation method for evaluating the deflection yoke based on the voltage difference.