JPH0346944B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a deflection device for a color picture tube, and particularly to a deflection device for a color picture tube of a convergence-free type.
The present invention relates to a deflection device for a color picture tube provided with means for correcting the following vertical distortion. In conventional deflection devices for color picture tubes,
As shown in FIG. 1, the image 2 drawn on the screen 1 on the inner surface of the face plate is represented by approximately quadratic curves at both the left and right ends in the horizontal axis (X) direction and the top and bottom ends in the vertical axis (Y) direction. It has the following distortion 3. In general, the magnitude of this distortion is higher and lower in a 90° deflection tube.
0.5%, and about 4% on the left and right sides. In recent color picture tubes, convergence-free deflection devices for large wide-angle deflection tubes have been put into practical use.
As shown in the figure, in addition to the quadratic vertical distortion 3 represented by a quadratic curve as shown in Figure 1 above and below the vertical axis (Y) direction of the image 2 drawn on the screen 1 on the inner surface of the face plate, , the fourth-order vertical distortion 4 represented by an approximately fourth-order curve increases, and these curves 3 and 4
The wave distortion 5 represented by the solid line curve is obtained by combining
occurs, leading to a decline in the quality of the reproduced image. This fourth-order vertical distortion 4 is caused by an increase in the deflection angle of the color picture tube, non-uniformity of the deflection magnetic field, etc., and is generally negative as shown in the figure. This wave distortion 5 can be corrected by a circuit, but in this case, a complicated circuit is required to flow a current that is synchronized with the deflection current and includes harmonic components of the deflection current, making it extremely difficult to put it into practical use. be. The present invention was made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a deflection device for a color picture tube that can minimize the fourth-order vertical distortion of the wave distortion by the deflection device itself. There is. Next, basic considerations of the present invention will be explained. Generally, vertical distortion is mainly affected by the horizontal deflection magnetic field.
Now the tube axis is the Z axis, the horizontal axis of the screen is the X axis, and the vertical axis is the Y axis.
The horizontal deflection magnetic field H is expressed as H=H ₀ +H ₂ x ² +H ₄ x ⁴ +... (1) on the X axis. Here, X is the horizontal distance from the tube axis, H ₂ is a coefficient representing second-order nonuniformity, and H ₄ is 4
It is a coefficient representing the following nonuniformity, and H ₂ is usually set to be positive (pink tension magnetic field) to realize convergence free. According to Kaashoek, the fourth-order vertical distortion 4Δy ₄ expressed by a substantially fourth-order curve due to the nonuniformity of the horizontal deflection magnetic field in FIG. 2 can be expressed by the following equation, which is a fourth-order equation of X _s . Δy ₄ = [∫ ^Zs _Z0 A(Z)H ₂ (Z)dZ +∫ ^Zs _Z0 B(Z)H ₄ (Z)dZ]X ⁴ _s Y _s ...(2) Here, Z ₀ is the third As shown in the figure, with the tube axis as the Z axis, the position where the electron beam enters the magnetic field of the deflection yoke, _Zs is the position of the screen, and _Xs and _Ys are the deflection distances in the X and Y axis directions, respectively. In FIG. 3, curve 6 shows the distribution of the deflection magnetic field (H) on the tube axis (Z). In A and B, the nonuniform components of the H ₂ and H ₄ magnetic fields are 4.
This shows the function of the weight given to the next vertical distortion, and means that the 4th order vertical distortion 4 involves the 2nd order asymmetry and the 4th order asymmetry. As an example, FIG. 4 shows the functions of each weight determined by measuring the magnetic field distribution of a deflection device for a 25V 110° deflection tube. That is, as shown by A and B in Fig. 4, the weight function of the fourth-order vertical distortion changes rapidly on the screen side of the deflection device, and the influence of H ₄ is particularly noticeable on the fourth-order vertical distortion. becomes. By the way, as mentioned above, the fourth-order vertical distortion based on the horizontal deflection magnetic field takes a negative value, so by H ₄ , (2)
By providing means for changing Δy ₄ in the equation in the positive direction, it becomes possible to reduce the fourth-order vertical distortion. On the other hand, as is well known, the influence of magnetism on the screen side is not large on convergence. Therefore, in order to reduce the fourth-order component of distortion without affecting other characteristics, it is sufficient to provide means for H ₄ to take a large negative value as close to the screen as possible. Now, in order to embody the above-mentioned correction principle, the one-turn saddle-shaped deflection coils 7 and 8 shown in FIG. 5 will be considered. These saddle-shaped deflection coils 7 and 8 correspond to the auxiliary coil portion of the embodiment described later. For the one-turn saddle-shaped deflection coils 7 and 8, H ₂ =kcos3θ/R ³ and H ₄ =kcos5θ/R ⁵ . However, θ is the angle (winding angle) between the horizontal axis (X) and the straight part of the coil (the part along the winding axis),
R is the radius of the coil whose origin is the tube axis (Z), and k is a constant. The specific relationship between the winding angle θ and H ₂ and H ₄ is shown by taking a 25V 110° deflection tube deflection device as an example.
Shown in the table below.

[Table] In the table above, the number of turns of the coil is one turn.
In the case of multiple turns, if the winding angle of the center of gravity of the straight part of the coil is θ, the relationship between θ and H ₂ and H ₄ will be almost the same as in the case of one turn. Here θ=26° is the current
It is the winding angle of the deflection device of the 25V110° deflection tube, and R is the radius of the straight part at the opening on the screen side. θ=30° is the value at which H ₂ becomes zero, θ=36° is the value at which H ₄
is the maximum negative value. If H ₂ is zero, then
Almost second-order distortion and convergence are not affected. On the other hand, for H ₄ , the difference in value between θ=30° and 36° is small. Therefore, it is optimal if the winding angle θ is approximately 30°. Next, embodiments of the present invention based on the above-mentioned basic considerations will be described. 6 and 7 are diagrams explaining the first embodiment of the deflection device of the present invention, and FIG. 6 mainly shows the H ₄
That is, it is a diagram of the auxiliary coil section 11 as means for correcting fourth-order vertical distortion. This auxiliary coil part 11 is a normal saddle-shaped coil, and the straight parts 12 and 13
The winding angle θ between the centers of gravity 14, 15 and the horizontal axis is Z
It is formed at approximately 30° along the axis. FIG. 7 shows the deflection device of this embodiment in which the auxiliary coil section 11 of FIG. The auxiliary coil portion 11 is connected to each other. In this case, the horizontal deflection coil 16 and the auxiliary coil section 11 are wired in series to provide the overall required impedance. 8 and 9 show a second embodiment of the deflection device of the present invention, in which an auxiliary coil section is provided on the screen side of a normal saddle-shaped horizontal deflection coil 26 as a means for correcting fourth-order vertical distortion. This is an extension of 21. This extended auxiliary coil section 21
H ₄ will be controlled by in this case,
Straight sections 22, 2 of the extended auxiliary coil section 21
The winding angle θ formed between the centers of gravity 24 and 25 of No. 3 and the horizontal axis is approximately 30°. Furthermore, FIGS. 10 and 11 show a third embodiment of the deflection device of the present invention, which includes a saddle-shaped auxiliary coil portion 31 extending toward the screen as a means for correcting fourth-order vertical distortion; It is formed by overlapping with a shorter normal saddle-shaped horizontal deflection coil 36. The auxiliary coil portion 31 and the electron gun side flange portion 3 of the saddle type horizontal deflection coil 36
The positions of 1 ₁ and 36 ₁ match. The auxiliary coil section 31 is superimposed on the horizontal deflection coil 36.
The winding angle θ between the centers of gravity 34, 35 of the straight parts 32, 33 and the horizontal axis is at least the horizontal deflection coil 36.
The part that protrudes further toward the screen is formed at an angle of approximately 30°. In this case, the auxiliary coil section 31 and the horizontal deflection coil 36 may be further divided into several coils, and at least one of them may be protruded toward the screen. In such a deflection device, H ₄ is
is controlled. All of the three embodiments described above have a structure that minimizes fourth-order vertical distortion by controlling _H4 , but as mentioned above, in the current self-convergence type color picture tube, Wave distortion is generated by the combination of the next vertical distortion and the fourth-order vertical distortion.
Since each of the auxiliary coil sections corrects the fourth-order distortion, even if the auxiliary coil section is provided as in each of the embodiments described above, the second-order distortion still remains in the deflection device. However, this second-order distortion can be corrected by controlling the pink tension magnetic field of the original horizontal deflection coil. Therefore, by using the deflection device of the present invention, it becomes possible to correct the distortion between the upper and lower waves to a minimum. That is, according to the deflection device of the present invention, it is possible to correct vertical wave distortion using the magnetic field of the deflection device itself without performing complicated circuit correction.
A good screen can be obtained at a low cost.

[Brief explanation of drawings]

Figure 1 is an illustration of screen distortion of a color picture tube with a small deflection angle, Figure 2 is an illustration of fourth-order vertical distortion and wave distortion of a color picture tube with a wide deflection angle, and Figure 3 is on the tube axis. FIG. 4 is a curve diagram showing an example of the distribution of the weight function for the fourth-order vertical strain of each magnetic field component in the tube axis direction. FIG. 5 is for explaining the principle of the present invention. FIGS. 6 and 7 are perspective views of a one-turn saddle-shaped horizontal deflection coil as an auxiliary coil portion, and FIGS. a and b are respectively a perspective view and a sectional view of the auxiliary coil section, FIG. 7 is a sectional view showing the auxiliary coil section of FIG. 6 connected to a convergence-free type horizontal deflection coil, and FIGS. 8 and 9. The figures show a second embodiment of the deflection device for a color picture tube according to the present invention, in which FIG. 8 is a perspective view, FIG. 9 is a sectional view, and FIGS. 10 and 11.
The figures show a third embodiment of the deflection device for a color picture tube according to the present invention; FIG. 10 is a perspective view;
Figure 1 is a cross-sectional view. 3...2nd order vertical distortion, 4...4th order vertical distortion, 5
... Wave distortion, 11, 21, 31 ... Auxiliary coil section, 12, 13, 22, 23, 32, 33 ... Straight section of auxiliary coil section, 14, 15, 24, 25,
34, 35... Center of gravity, 16, 26, 36... Horizontal deflection coil.

Claims (1)

[Claims] 1. In a deflection device for a convergence-free color picture tube equipped with a saddle-shaped horizontal deflection coil, the saddle-shaped horizontal deflection coil has a straight line along the tube axis of the winding at the screen side end. A deflection device for a color picture tube, characterized by having an auxiliary coil part whose winding angle between the center of gravity of the part and the horizontal axis is approximately 30 degrees. 2. An auxiliary coil part is connected to the screen-side end of the saddle-shaped horizontal deflection coil in which the winding angle between the center of gravity of the straight line part along the tube axis of the winding wire and the horizontal axis is approximately 30°. A deflection device for a color picture tube according to claim 1. 3. A part of the saddle-shaped horizontal deflection coil is extended in the direction of the screen to form an auxiliary coil part in which the winding angle between the center of gravity of the straight line part along the tube axis of the winding wire and the horizontal axis is approximately 30°. A deflection device for a color picture tube according to claim 1. 4. The auxiliary coil portion is overlapped with the saddle-shaped horizontal deflection coil, and has a portion that protrudes in the screen direction from the screen side end of the horizontal deflection coil, and at least the tube axis of the winding of the portion that protrudes in the screen direction. 2. A deflection device for a color picture tube according to claim 1, wherein a winding angle between the center of gravity of the straight line portion along the horizontal axis and the horizontal axis is approximately 30°.