JPH0554827A - Deflection yoke - Google Patents

Abstract

PURPOSE:To correct misconvergence resulting from axial displacement concerning convergence characteristics without causing oscillation of a deflection yoke. CONSTITUTION:Convergence correcting coils 2, 3 are provided near both sides of the horizontally deflecting coils 5 of a deflection yoke and the correcting coils 2, 3 are provided with a differential coil 4 comprising a first 6 and second 7 coil both serving an inductance adjusting means. The balance of a horizontally deflected magnetic filed in the horizontal direction is changed by the inductances of the first 6 and the second 7 coil and thereby misconvergence resulting from axial displacement concerning convergence characteristics is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection yoke used in a color cathode ray tube having an in-line type electron gun.

[0002]

2. Description of the Related Art FIG. 11 is a partially broken perspective view of an in-line type color cathode ray tube in which phosphor dots (or stripes) of three colors (usually red, green and blue) are regularly arranged. The screen 20 is composed of a panel 21 formed on the inner surface, a funnel-shaped funnel 24, and a neck 25. An electron beam passage hole 22 is formed on the main surface of the panel 21 so as to closely face the screen 20 on the inner surface of the panel 21. The shadow mask 23 is formed.

Inside the neck 25, an in-line type electron gun 26 arranged in a straight line for focusing and emitting three electron beams red (R), green (G) and blue (B) is arranged. A deflection yoke 27 is arranged on the outer wall of the cone portion of the funnel 24.

A feature of the in-line type electron gun 26 is that the deflection yoke 27 generates an inhomogeneous magnetic field so that only the combination of the color cathode ray tube and the deflection yoke can be used for the entire screen without using a circuit correction means. The R, G, B electron beams are made to substantially coincide with each other, that is, so-called self-convergence is realized.

At present, the most predominant type of in-line type color cathode ray tube is the above-mentioned self-convergence type, which also corrects the raster distortion at the top and bottom of the screen at the same time.

Next, the principle of self-convergence by the deflection yoke will be described. Normally, the deflection yoke is formed of two coils, that is, a horizontal deflection coil and a vertical deflection coil. However, when the distributions of the magnetic fields generated by these two coils are uniform, the convergence characteristic on the screen is as shown in FIG. As a result, the R, G, B electron beams cannot be matched on the screen.

However, as shown in FIG. 13, the horizontal deflection magnetic field 1
By setting 1 as the pincushion-shaped magnetic field and the vertical deflection magnetic field as the barrel-shaped magnetic field 13, a difference occurs in the deflection force with respect to the R, G, B electron beams, and thereby the R, G, B electron beams are made to coincide on the screen. It becomes possible.

The problem with this method is that
When variations occur in the three electron guns 26 and the horizontal / vertical deflection coils 27 due to manufacturing errors of the cathode ray tube and the deflection yoke, a deviation occurs between the orbital center of the electron beam and the central axis of the distribution of the deflection magnetic field. Is usually referred to as "axis misalignment"), and the convergence on the screen is disturbed.

FIGS. 10 (a) and 10 (b) are views showing an example of the axis deviation, which shows the convergence characteristic (XH) when the horizontal deflection magnetic field is laterally displaced from the center of the orbit of the electron beam.

Conventionally, as a method of correcting these axis deviations, a "necking" operation of the deflection yoke 27 as shown in FIG. 14 has been performed. This is the deflection yoke 27 on the cathode ray tube.
At the time of setting, the deflection yoke 27 is oscillated vertically and horizontally with the tightening band portion 34 of the deflection yoke 27 as a fulcrum to adjust the axial position of the deflection magnetic field to correct the axial deviation.

[0011]

However, when the axial deviation is corrected by this method, there is a big problem that the raster distortion on the screen is deteriorated. This is because when the deflection yoke is moved with the tightening band portion on the neck side of the deflection yoke as a fulcrum, the screen side of the deflection yoke moves greatly, and the magnetic field on the screen side of the deflection yoke changes to the magnetic field on the neck side. This is because the influence on the raster distortion characteristics is greater than that on the other hand.

The present invention has been made in order to solve the above problems, and provides a deflection yoke capable of correcting misconvergence due to misalignment of the convergence characteristic without finely moving the deflection yoke. The purpose is to

[0013]

In the deflection yoke according to the present invention, a pair of convergence correction coils are provided on both sides of the horizontal deflection yoke in the vicinity of the x-axis, and the inductance of the correction coils is differentially varied to make horizontal. The feature is that the left and right balance of the deflection magnetic field is changed to correct the misconvergence due to the axis deviation of the convergence characteristic.

[0014]

According to the present invention, by differentially varying the inductance of the convergence correction coil, the horizontal balance of the main horizontal deflection magnetic field can be adjusted, and misconvergence due to axial deviation of the convergence characteristics is corrected. be able to.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of this embodiment, and FIG. 2 is an equivalent circuit diagram of this embodiment. In the figure, 1 is a toroidal core, 2 and 3 are convergence correction coils wound around the toroidal core 1, 4 is a screw core type differential coil that adjusts the inductance of the convergence correction coils 2 and 3, and 5 is a horizontal deflection coil, Reference numerals 6 and 7 are first and second coils that configure the differential coil 4, and the convergence correction coil 2 and the first coil 6 are connected in series, and the second coil 7 and the convergence correction coil 3 are connected in series. The other ends of the convergence correction coils 2 and 3 are connected to a connection point between the first coil 6 and the second coil 7.

FIGS. 3 to 5 are views showing a concrete example of the structure of the differential coil 4, in which a cylindrical bobbin 8 has a first coil 6 on one side and a second coil 7 on the other side. Each is wrapped. Reference numeral 9 denotes a screw core inserted into a screw hole inside the cylindrical bobbin 8, and is configured to rotate the screw core 9 to move the screw core 9 in the axial direction.

Next, the operation will be described. First, when the screw core 9 is located at the center of the bobbin 8, that is, the inductance of the horizontal deflection convergence correction coil 2 and the differential coil 4 on the side of the first coil 6 and the second deflection of the convergence correction coil 3 and the differential coil 4. When the inductance on the coil 7 side is the same, the left-right balance of the horizontal deflection magnetic field does not change.

Next, when the screw core 9 is moved in the axial direction from the center of the bobbin 8, for example, when it is moved to the first coil 6 side, the inductances of the convergence correction coil 2 and the first coil 6 are , The other coil 3,
7, the horizontal deflection magnetic field in this case becomes as shown in FIG. 6, and the convergence at this time becomes the pattern as shown in FIG.

When the screw core 9 is moved to the coil 7 side, the inductances of the convergence correction coil 3 and the second coil 7 become larger than the inductances of the other coils 2 and 6, and horizontal deflection in this case is caused. The magnetic field is as shown in FIG. 8, and the convergence at this time has a pattern as shown in FIG.

That is, by adjusting the position of the screw core 9, as shown in FIG.
Misconvergence due to axial deviation of the convergence characteristics such as 0 (a) and (b) can be corrected without finely moving the deflection yoke.

In the above embodiment, an example in which the convergence correction coils 2 and 3 are wound around the toroidal core 1 has been described, but other devices may be used as long as they can change the left and right of the horizontal deflection magnetic field. The same effect as that of the above embodiment is obtained.

[0022]

As described above, according to the present invention, the first and second auxiliary coils respectively disposed near the X axis on both sides of the horizontal deflection coil, and the first and second auxiliary coils. A means for differentially increasing or decreasing the inductance of the coil is provided, and the inductance of the first and second auxiliary coils is changed to change the strength of the left and right horizontal deflection magnetic fields to correct the axis deviation. There is an effect that it is possible to obtain a deflection yoke that can correct an axis deviation between the deflection yoke and the cathode ray tube without finely moving the deflection yoke.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram of the convergence correction coil device in this embodiment.

FIG. 3 is a front view of the convergence correction coil device.

FIG. 4 is a side view of the convergence correction coil device.

FIG. 5 is a vertical sectional view of this convergence correction coil device.

FIG. 6 is a horizontal deflection magnetic field distribution diagram when the inductance of the first coil of the convergence correction coil device is increased.

FIG. 7 is a diagram showing a misconvergence pattern on the screen when the magnetic field is distributed in FIG. 6;

FIG. 8 is a horizontal deflection magnetic field distribution diagram when the inductance of the second coil of the convergence correction coil device is increased.

9 is a diagram showing a misconvergence pattern on the screen when the magnetic field is distributed in FIG. 8;

FIG. 10 is a diagram for explaining an axis shift of the convergence characteristic.

FIG. 11 is a partially cutaway perspective view of an in-line type color cathode ray tube.

FIG. 12 is a diagram showing a misconvergence pattern on a screen when a deflection yoke having a uniform magnetic field is used.

FIG. 13 is a magnetic field distribution diagram showing a horizontal deflection pincushion-shaped magnetic field and a vertical deflection-shaped magnetic field.

FIG. 14 is a side view showing an attached state of a conventional deflection yoke.

[Explanation of symbols]

 1 Toroidal core 2, 3 Convergence correction coil 4 Differential coil 5 Horizontal deflection coil 6 First coil 7 Second coil 9 Screw core

Claims (1)

[Claims] 1. A deflection yoke mounted on a color cathode ray tube having an in-line type electron gun, wherein first and second auxiliary coils are arranged on both sides of a horizontal deflection coil near the x-axis. And a means for differentially changing the inductances of the first and second auxiliary coils.