JPS5827715B2 - Color cathode ray tube convergence correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a convergence correction device for, for example, a color cathode ray tube having an in-line electron gun, and is particularly intended to improve image quality.

There is a cathode ray tube having an in-line electron gun as shown in FIG.

The figure is a diagram whose cut plane is in the horizontal direction of the screen, and KR,
KG and KB indicate red, green and blue cathodes arranged in sequence in the horizontal direction, and these red, green and blue cathodes KR
.

Common 1st to 5th grids 01 to KQ and KB
G, are arranged sequentially with the same axis.

Electron beams R, G and B corresponding to red, green and blue, respectively, from cathodes KR1KG and KB are formed by an auxiliary electron lens Ls formed by second and third grids G2 and G3.
The third to fifth grids G3 to G
, and are designed to intersect and diverge approximately at the center of the main electron lens LM formed by the main electron lenses LM.

A static convergence means 1 is provided in the middle of the divergence of the electron beams R, G and B, and its inner deflection type polar plates 2 and 3
An anode voltage Eb is applied to the outer deflection electrode plate 4.
A static convergence operation is performed by applying a convergence voltage Ec, for example, 1300 V lower than the anode voltage Eb, to the anode voltage Eb in a 22-inch color cathode ray tube.

In this case, the static convergence is corrected so that the three electron beams coincide at the center of the screen S of the color cathode ray tube, as shown in FIGS. 2 and 4.

A dynamic convergence means 6 is provided outside the tube corresponding to the position where the static convergence means 1 is disposed, and when the static convergence means 1 performs static convergence correction as shown in FIG. 2, for example, as shown in FIG. The dynamic convergence operation is performed using a parabolic wave-like correction current with a horizontal period H as shown in FIG.

When the static convergence result is as shown in Figure 4, dynamic convergence is corrected using a current obtained by superimposing a parabolic wave current with a vertical period ■ on a parabolic wave current with a horizontal period H as shown in Figure 5. It has become.

Note that 7 is horizontal and vertical deflection means.

The dynamic convergence means 6 for performing such a correction operation may be constructed as shown in FIG. 6, for example.

The figure is a sectional view when viewed from the screen S side, and this example has U-shaped cores 8 and 9, which are horizontally opposed to each other across the neck part, and each core 8 and 9
Coils 10 and 11 are wound around the coils 10 and 11, respectively, and therefore, a four-electrode structure is used in which the above-described horizontally periodic parabolic wave current is passed through these coils 10 and 11.

The example shown in FIG. 1 shows a case in which striped phosphors of red, green, and blue are repeatedly arranged in sequence in the horizontal direction to form a color phosphor surface.

In this way, conventionally, the static convergence means 1
As shown in FIGS. 2 and 4, the misconvergence is corrected so that the three electron beams match in the center of the screen S, and the other areas are corrected by the dynamic convergence means 6. The closer the electron beam approaches the periphery of the screen S of the cathode ray tube, the more the electron beam reaching there is influenced by the strong magnetic field from the dynamic convergence means 6, which has the disadvantage that the cross-sectional shape of the beam is distorted.

That is, when the dynamic convergence current is zero, the beam spot on the screen S becomes circular as shown in FIG. Since the magnetic field H1 is generated in the horizontal direction and the magnetic field H2 is generated in the horizontal direction, there is a force F1 that pulls each beam in the horizontal direction and a force F2 that crushes it in the vertical direction.
(Figure 6 is a view from the S side of the screen),
Therefore, as shown in FIG. 8, the beam spot shape on the screen becomes a flat circular shape.

For this reason, the conventional device had a drawback in that image quality (mainly focus resolution) deteriorated toward the periphery of the screen.

In this case, in a deflection state where the electron beam is located at the right end of the screen S when viewed from the screen side, the direction of the horizontal deflection magnetic field generated by the deflection coil 7 is upward, as shown by the dotted arrow a. This is the same direction as the magnetic field H1 generated by the dynamic convergence correction current.

Therefore, the electron beam is further distorted in the horizontal direction based on the magnetic field generated by the deflection coil 7 shown by the arrow a, and the distortion in the beam shape is further exacerbated.

In view of this, the present invention corrects the outside of the effective screen of a color cathode ray tube using static convergence, and also corrects the inside of the effective screen using dynamic convergence, thereby eliminating the deterioration in image quality due to beam shape distortion. be.

An embodiment of the convergence correction device for color cathode rays t according to the present invention will be described below with reference to the drawings.

In this example, an anode voltage Eb is applied to the inner deflection electrode plates 2 and 3 of the static convergence means 1 in the configuration shown in FIG. For the second color cathode ray tube,
Convergence voltage E slightly lower than anode voltage Eb
c, that is, in the present invention, the voltage difference between the inner and outer deflection electrode plates 2, 3 and 4, 5 by the static convergence means 1 is made smaller than before, and convergence occurs outside the effective screen S as shown in FIG. Therefore, correction is made so that the three electron beams R, G, and B match outside the effective screen.

In this case, as shown in FIG. 9, within the effective screen S, under-correction occurs, and misconvergence must be corrected by the dynamic convergence means 6 disposed outside the screen.

Here, as shown in FIG. 9, the under-correction extends not only to the center of the screen S but also to both left and right ends of the screen S,
Moreover, the degree of under-correction is greatest in the center.

Therefore, in order to correct such □ sconvergence, the correction current is largest in the negative direction at the center and becomes smaller toward both the left and right ends in the horizontal direction of the screen S, and the effective off-screen Q shown in FIG. It is sufficient to supply a correction current that becomes zero at virtual positions L1°L2 where static convergence is achieved.

That is, it is sufficient to supply a correction current to the dynamic convergence means 6 such that the convergence correction magnetic field at both left and right ends does not become zero. Therefore, the correction signal sD for dynamic convergence is synchronized with the horizontal period as shown in FIG. A parabolic waveform signal as shown in is used.

Note that the DC bias current JiO value of the correction current at both the left and right ends of the screen S is selected so that convergence can be achieved at both the left and right ends with the correction magnetic field based on this current value.

FIG. 11 shows specific means for achieving the above-mentioned dynamic convergence, and in this example, a four-electrode configuration is used as in the prior art.

However, the polarity is opposite.

By the way, in the current deflection state where the electron beam is located at the right edge of the screen S when viewed from the screen side, the direction of the horizontal deflection magnetic field generated by the deflection coil 7 is upward as shown by arrow a, so that the electron beam A force F,' as shown by the dotted line acts on the beam, causing the electron beam to be distorted in the horizontal direction.

However, the correction signal s supplied between the terminals 10a and lla
Since the correction magnetic field H1 generated by D is in the opposite direction to the horizontal deflection magnetic field, the force F1 generated by this correction magnetic field H1 is in the opposite direction to the force F1'.

Therefore, the forces F1 and F1' cancel each other out, and the electron beam is not distorted.

Such development occurs not only particularly at the right end of the screen S, but also over the entire screen S.

As explained above, the present invention is particularly configured to perform static convergence outside the effective screen, and to correct under-correction within the effective screen S caused by this static convergence by dynamic convergence. be.

Therefore, with this configuration, not only can misconvergence be effectively corrected, but also beam shape distortion that appears particularly at both the left and right ends of the screen S (including the four corners of the screen S) can be effectively and reliably corrected. .

The electron beam near the center of the screen S has passed through the vicinity of the central space of the deflection coil 7 and the dynamic convergence means 6, and the magnetic field near this central space has relatively little distortion in the magnetic field distribution and is Since the beam spot shape on S is not susceptible to distortion and the incident angle is close to zero, the distortion of the beam spot shape is small as a result.

As is clear from the above, according to the present invention, the image quality (resolution, sharpness, etc.) of the entire screen S can be significantly improved compared to the conventional method.

In the above-mentioned embodiment, a convergence correction device corresponding to the conventional example shown in FIG. 2 was described, but in the case shown in FIG. It goes without saying that the configuration is such that static convergence can be achieved at any arbitrary position, L2.

In order to correct the misconvergence shown in this figure, the dynamic convergence means 6 must have a current that is approximately zero at some of the four corners outside the effective screen, as shown in FIG. What is necessary is to apply a correction current that is as follows.

To do this, a parabolic wave current with a horizontal period H and a vertical period ■
It is sufficient to supply a correction signal SD' on which a parabolic waveform current of .

In addition, when correction is made so that static convergence is obtained at both left and right ends of the effective screen, for example, without taking static convergence outside the effective screen as in the present invention, the correction magnetic field becomes zero at both left and right ends of the dynamic convergence. In order to perform such correction, the deflection coil γ is
The shape of the beam that has been distorted by the horizontal and vertical deflection magnetic fields is not corrected, and the distortion caused by the deflection magnetic fields remains in the periphery of the screen, so that the effects of the present invention cannot be achieved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an example of a color cathode ray tube having an in-line electron gun, FIGS. 2 to 5 are diagrams for explaining a conventional convergence correction device for a color cathode ray tube, and FIG. 6 is a sectional view showing an example of the dynamic convergence means, FIGS. 1 and 8 are diagrams for explaining the shape of the electron beam, respectively, and FIGS. FIG. 11, which is a diagram for explaining the invention, is a sectional view showing an example of a dynamic convergence means that can be used in the apparatus of the present invention. 1 is a static convergence means, 6 is a dynamic convergence means, and S is a color cathode ray tube screen. L4. L2 indicates a position outside the effective screen.

Claims (1)

[Claims] 1. A convergence correction device for a color cathode ray tube, characterized in that the area outside the effective screen of the color cathode ray tube is corrected by static convergence, and the area within the effective screen is corrected by dynamic convergence.