JPS6224542A - Beam spot correcting device for cathode-ray tube - Google Patents

Abstract

PURPOSE:To correct distortion of beam spot over the entire area of screen by feeding parabolic current of horizontal scanning period to one yoke of tetra- pole structure while feeding saw-tooth current of horizontal period to the other yoke. CONSTITUTION:Parabolic current IPA and saw-tooth current ISA are fed respectively to the yokes 10, 20 to produce magnetic field. Consequently, respective electron beam BR, BG, BB is subjected to force. In the yoke 10, horizontal and vertical forces will function onto the electron beams BR, BG, BB while in yoke 20, force in the direction of 45 deg. will function onto the yoke 20. Consequently, distortion of beam spot can be corrected over the entire area on the screen.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a beam spot correction device for a cathode ray tube that corrects distortion of a beam spot on a screen.

B0 Summary of the Invention The present invention provides a beam spot correction device for a cathode ray tube that corrects beam spot distortion on a screen, in which a correction yoke consisting of two yokes of a quadrupole structure is provided outside the cathode ray tube, and a correction yoke is provided outside the cathode ray tube. By forming a magnetic field, distortion of the beam spot can be corrected over the entire area on the screen.

C1 Prior Art Conventionally, cathode ray tubes (so-called cathode ray tubes) have been widely used in television receivers and the like as means for displaying images and the like. Here, an example of a color cathode ray tube will be described. That is, the three electron beams emitted from the red, green, and blue color cathodes pass through the first to fifth grids and convergence electrodes, and then are deflected horizontally and vertically by the deflection yoke to perform color sorting. It is designed to reach the fluorescent surface via an electrode. Further, convergence is corrected by a dynamic convergence yoke installed near the convergence electrode on the outer periphery of the neck portion.

D1 Problem to be Solved by the Invention However, the horizontal and vertical deflection by the deflection yoke and the correction of convergence by the dynamic convergence yoke are all due to electromagnetic action, and either one of the deflection yoke or the dynamic convergence yoke or Due to the magnetic fields generated by both, the beam spot on the screen is distorted into a circular shape in a region other than the center of the screen 100, as shown in FIG. 9, for example. As for the correction of beam spot distortion due to the magnetic field generated by the dynamic convergence yoke, it is known to use a correction yoke having a quadrupole structure as described in, for example, Japanese Utility Model Publication No. 56-46297. According to such a correction yoke, for example, as shown in FIG.
0 horizontal direction (X-axis direction) and vertical direction (Y-axis direction)
Although it is possible to correct distortions in other directions, such as distortions in beam spots located near corners (parts of corners) of the screen 100, it is not possible to correct distortions in other directions.

Therefore, the present invention was proposed in view of the above-mentioned conventional problems, and corrects the distortion of the beam spot caused by the magnetic field generated by either or both of the deflection yoke and the dynamic convergence yoke in the entire area on the screen. Means for Solving Problems In order to achieve the above-mentioned object, the cathode ray tube beam spot correction device according to the present invention uses a correction yoke formed by integrating two yokes with a Φ heavy pole structure as a cathode ray tube beam spot correction device according to the present invention. Provided on the outer periphery of the neck of the tube, it supplies a parabolic current with a horizontal scanning period to one yoke of the quadrupole structure, and supplies a sawtooth current with a horizontal scanning period to the other yoke of the quadrupole structure. It is characterized by correcting beam spot distortion using the resulting composite magnetic field.

F. Function According to the present invention, magnetic fields are formed by each yoke of the quadrupole structure constituting the correction yoke, and the force of these combined magnetic fields acts on the electron beam.

G. Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the beam spot correction device of this embodiment. In FIG. 1, the correction yoke 1 is made by integrating two yokes with a quadrupole structure, and includes cores 11, 12, 13i4, which constitute the yoke 10, and cores 21, 22, and 22, which constitute the yoke 20, respectively. 23 and 24 are arranged alternately with an angular spacing of 45''.
1.12, 13.14 have coils 15, 16, 17
, T8 are respectively wound, and the core 21
, 22°23.24 has a coil 25.26.27.28
are each wrapped. Further, the coils 15 to 18 of the yoke 10 are connected in series, with the coil 15 being connected to the power supply terminal 30, and the coil 18 being connected to the current amplifier 31, respectively. On the other hand, the coils 25 to 2 of the yoke 20
8 are also connected in series, and the coil 25 is connected to the power terminal 30.
The coils 28 are each connected to a current amplifier 32 .

Flyback pulse PFB from the horizontal output circuit (not shown)
The terminal 33 to which is supplied is connected to a parabolic wave modulation circuit 35 via a coil 34 and further connected to a sawtooth wave modulation circuit 37 via a capacitor 36.

The parabolic wave modulation circuit 35 connects the current amplifier 31 to
The sawtooth modulation circuits 37 are connected to the current amplifiers 32, respectively. Further, a terminal 38 is supplied with a sawtooth wave VSA having a vertical scanning period from a vertical output circuit (not shown).
are connected to the parabolic wave modulation circuit 35 and the sawtooth wave modulation circuit 37, respectively.

In other words, a parabolic wave with a horizontal scanning period based on the flyback pulse PFB supplied to the terminal 33 is supplied to the parabolic wave modulation circuit 35, and a sawtooth wave with the same horizontal scanning period is supplied to the sawtooth wave modulation circuit. 37. Then, the parabolic wave modulation circuit 35 performs a process of modulating the parabolic wave with a vertical scanning period, and this output is amplified by a current amplifier 31. 18.

On the other hand, the sawtooth wave modulation circuit 37 performs a process of modulating the sawtooth wave in a vertical scanning period, and this output key is amplified by a current amplifier 32, and the sawtooth current ISA in the horizontal scanning period is applied to the coil 25 of the yoke 20. The correction yoke 1, which will be supplied to the tubes 1 to 28, is provided, for example, on the outer periphery of the neck portion 41 of a cathode ray tube as shown in FIG. In the case of this cathode ray tube, the correction yoke 1 is provided near the main electron lens LM formed by the third to fifth grids G3 to G5. Here, the main structure of this cathode ray tube will be schematically explained.

Inside the neck part 41 are cathodes K of each hue of red, green, and blue.
R, Ka, Kn, 1st to 5th crits Cb.

~G5, and a set of four convergence electrodes (concentration deflection plates) 42 are provided, and cathodes KR, Ka
, KB, each electron beam BR, BG.

After BB is prefocused by the auxiliary electron lens Ls formed by the second to third grids 02 to G3, it intersects and diverges at the center of the main electron lens LM formed by the third to fifth grids 08 to G5. The electron beams BR, Be, and Bn are deflected by the convergence electrode 42 so as to be concentrated on a fluorescent surface (not shown).

In addition, a Quinaminck convergence yoke 43 and a deflection yoke 44 for correcting convergence are installed outside the tube.
is provided.

Specific examples of the parabolic current Ip supplied to the yoke 10 and the sawtooth current ISA supplied to the yoke 20 are shown in FIGS. 3 and 4, respectively. 3 and 4 show the current value for the electron beam that lands on each point on the screen, and the area surrounded by the broken line corresponds to the screen. Note that the vertical position is determined by the positions of seven axes arranged at equal intervals.

Such parabolic current IPA and sawtooth current Is
When a person is supplied to the yoke 10 and the yoke 20, a magnetic field as shown in FIG. 5, for example, is generated and acts on the electron beam. For convenience, FIG. 5 shows the yoke 10 and the yoke 20 separately as seen from the screen side, and the coils are omitted.

That is, when 12 parabolic currents and a sawtooth current ISA are supplied to each yoke 10, 20, a magnetic field as shown, for example, by the broken line in the figure is generated.

Each electron beam BR, BG is generated by these magnetic fields.

Bn is subjected to a force as shown by the dashed line in the figure. Considering each of these, in the yoke 10, forces in the horizontal direction (X-axis direction) and in the vertical direction (Y-axis direction) act on the electron beams BR, BG and BB, and in the yoke 20, forces in an oblique 45° direction is the electron beam BR, Ba
, acts on BB. Although the direction of this force is diagonal at 45° in this embodiment, it can be set arbitrarily by varying the angular spacing between the cores 21 to 24.

In this way, by applying a force to the electron beams BR, BG, and BB in advance using the yoke 10 and the yoke 20, distortion of the beam spot on the screen can be corrected. Specifically, the horizontal direction (X-axis direction) and vertical direction (
Yoke 10 for beam spot distortion in Y-axis direction)
Distortion in other directions, for example, distortion of the beam spot located near the corners of the screen 50, can be corrected by the yokes 10 and 20. The two yokes 10.2 correct the distortion of the beam spot located near the corner of the screen 50.
The reason why the screen is set to 0 is because the aspect ratio of the screen is usually 3 pairs, and unlike the illustration, it cannot be corrected by the yoke 20 alone. Therefore, the yoke 10 corrects the distortion of the beam spot that is distorted in the angle direction shown in FIG. 7A.

Therefore, according to the beam spot correction device of this embodiment,
As shown in FIG. 8, it is possible to correct the distortion of the beam spot in the entire area of the screen 50, and it is possible to obtain a good beam spot that is approximately perfectly circular. Further, since the correction yoke 1 is installed near the main electron lens LM, it goes without saying that it does not affect the deflection operation by the deflection yoke 44 and the convergence correction operation by the dynamic convergence yoke 43.

Note that the present invention can also be applied to color cathode ray tubes and monochrome cathode ray tubes having different configurations from those described in this embodiment. It must be installed near the main electron lens. Further, in a monochromatic cathode ray tube, although the position of the correction yoke is not specified, it is preferable to install it near the main electron lens, which has a large lens effect.

H0 Effects of the Invention As is clear from the description of the embodiments described above, according to the beam spot correction device for a cathode ray tube according to the present invention, a parabolic current having a horizontal scanning period is supplied to one of the yokes constituting the correction yoke. At the same time, by supplying a sawtooth current having a horizontal scanning period to the other yoke to form a correction magnetic field, distortion of the beam spot can be corrected in the entire area on the screen IJ.

[Brief explanation of the drawing]

1 to 8 are diagrams for explaining one embodiment of the present invention. FIG. 1 is a configuration diagram showing a beam spot correction device for a cathode ray tube according to the embodiment, and FIG. A plan sectional view of a cathode ray tube showing the arrangement position, FIG. 8 is a diagram showing a specific example of a parabolic current, FIG. 4 is a diagram showing a specific example of a sawtooth current, and FIG. 5 is a diagram showing the action of a correction yoke. Diagrams for explanation, Figure 6 is supplementary, Figure 7 A and Figure 7 B are located near the corner of the screen.
FIG. 8 is a front view of a screen showing the corrected beam spot. 9 and 10 are diagrams for explaining the conventional example, in which FIG. 9 is a front view of the screen showing the beam spot before correction, and FIG. 1O is a front view of the screen showing the beam spot after correction. It is. 1......Correction yoke 10.20...Old 31.32...Current amplifier 33.38...・・・Terminal

Claims (1)

[Claims] A correction yoke formed by integrating two yokes with a quadrupole structure is provided on the outer periphery of the neck portion of the cathode ray tube, and a parabolic current with a horizontal scanning period is applied to one yoke of the quadrupole structure. beam spot correction for a cathode ray tube, characterized in that a sawtooth current with a horizontal scanning period is supplied to the other yoke of the quadrupole structure, and distortion of the beam spot is corrected by the obtained composite magnetic field. Device.