JPH0435869B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a color picture tube equipped with multiple electron guns arranged in a straight line, and the multiple electron guns emit electron beams substantially in parallel in an undeflected state. This invention relates to a deflection yoke for a color picture tube, which is constructed in the same manner as described above.

Technical Background of the Invention A conventional color picture tube will be explained with reference to FIGS. 1 to 3. As shown in Figure 1, a conventional color picture tube with a so-called shadow mask or in-line array multiple electron guns has a dot-shaped phosphor layer on its inner surface that emits red, green, and blue light when an electron beam strikes it. Alternatively, a face plate 1 on which fluorescent surfaces 2 are adhered and arranged regularly in a band shape, and a plurality of panel pins 5 embedded in the inner wall of the side wall portion (1-1) of this face plate 1 are connected to springs 6. and a shadow mask 3 having a plurality of openings 12, which serve as electric beam passage holes, arranged opposite to each other at a predetermined distance from the fluorescent surface 2 via the mask frame 4, and an inner layer provided as necessary. The electron gun 1 is connected to the shield 14 and the side wall (1-1) through the funnel 7.
A wedge (8-2) is interposed between the color picture tube main body connected to the net 9 housing the color picture tube 0 and the outer wall of the funnel 7, which is fixed to the outer wall of the neck 9 by a support part (8-1) and the outer wall of the funnel 7. It consists of an attached deflection device 8 and an adjusting magnet 11 attached to the outer wall of the net 9, and the electron beam 13 emitted from the electron gun 10 is directed to a predetermined location on the fluorescent surface 2 through the opening 13 of the shadow mask 3. make the phosphor layer emit light.

This electron gun 10 is usually red, green, and blue (hereinafter referred to as R).
Three electron beams, R, G, and B, are formed to cause each of the phosphors emitting light to emit light in an incidental manner.
These color picture tubes, commonly called three-beam shadow mask tubes, are now called in-line electron guns. The mainstream is an electron gun in which three electron guns are arranged horizontally in a row. In a color picture tube using such an in-line electron gun, each electron beam (hereinafter referred to as R, G, B beam) causes each color phosphor of R, G, and B to emit light.
is designed to be concentrated at one point on the fluorescent surface 2 due to the dimensions of the focusing electrode of the electron gun 10, etc., when the deflection yoke 8 is not operated and there is no deflection. In reality, the electron gun 2 and shadow mask 3 are not accurately focused due to assembly errors, etc., so fine adjustment is performed using the adjustment magnet 11.

Furthermore, in the in-line array electron gun, by appropriately designing the magnetic field of the deflection yoke 8, it is possible to cause the R, G, and B3 beams during deflection to simultaneously pass through one point of the shadow mask 3. In a picture tube having an in-line array electron gun, such a so-called dynamic convergenceless magnetic field design is possible, and compared to a picture tube having a so-called delta type electron gun, a convergence yoke is not required, and no complicated adjustment is required. Because of its many advantages, most current color picture tubes use in-line electron guns. An example of a dynamic convergenceless magnetic field will be explained with reference to FIG. The dynamic convergenceless magnetic field is a so-called barrel magnetic field in which the vertical deflection magnetic field 23 shown by the solid line decreases in intensity as it moves away from the center, and the intensity of the horizontal deflection magnetic field 22 shown by the broken line increases as it moves away from the center. This is a so-called pink tension magnetic field.
In this way, a dynamic convergence magnetic field is realized by distorting the magnetic field from the same so-called uniform magnetic field regardless of the distance from the center.
Further, a method of removing pattern distortion, which was conventionally corrected by a circuit, using a deflection magnetic field is becoming common, and such a magnetic field tends to further intensify the distortion of the deflection magnetic field.

Problems with the Background Art By the way, when the distortion of the deflection magnetic field is increased in this way, good convergence or pattern distortion characteristics can be obtained, but problems appear in other aspects. That is, by distorting the deflection magnetic field, the spot of the electron beam becomes increasingly distorted. Therefore, when deflected, the electron beam spreads, so-called "bleeding" increases, and the resolution at the periphery of the screen drops significantly, making it impossible to obtain a satisfactory screen. Furthermore, if the electron beam spot around the screen spreads, a compromise design between the center of the screen and the periphery of the screen must be made in the design of the electron gun, which becomes a major obstacle in the design of the electron gun. Further, Japanese Patent Publication No. 57-4061 describes a dynamic convergence device using a color television receiver using a video signal delay device. According to the present invention, the color picture tube is designed so that the three electron beams are not concentrated at one point on the shadow mask in a state where the deflection yoke is not operated, that is, in a non-deflected state, so that so-called static convergence is insufficient. As a result, the R, G, and B3 beams are not concentrated on the screen, resulting in color shift in the three-color pattern. In Figure 3, if the R, G, and B3 beams are accurately focused, a correct screen will be reproduced. R,
If the G and B3 beams have insufficient static convergence, the pattern will be 31-B, 31-G, 31-R, 32-B, 32 as shown in Figure 3.
-G, 32-R, resulting in an image with color shift. For this reason, this color shift is delayed to some signals of the R, G, and B3 beams in order to correctly reproduce the image. Therefore, if the correct delay is given to the image signal, 31-R, G, B,
32-R, G, and B match and a correct image is reproduced.

A color television using a delay circuit will be explained based on the drawings. Here, all the numbers in the drawings after FIG. 4 are the same as those in FIG. 1 and indicate the same members.

In FIG. 4, a signal source 41 generally supplies signals for driving the R, G, and B color electron guns. 42-G and 42-B are delay circuits, and the fourth
In the figure, it is inserted in pairs in the signals that drive the G beam and B beam, but it may be delayed for all three R, G, and B color signals, or any one color or two color signals can be delayed.
The configuration may be such that a delay is applied to the colors. Further, a signal whose delay is controlled in advance may be generated from the signal source 41 without using the delay circuits 42-G and 42-B. 43 is R, G, B3
Color electron beams are shown, and although they are nearly parallel in FIG. 4, they may be tilted to some extent. That is, the term "substantially parallel electron beam" refers to one having an inclination within 1/2 of the convergence angle of a conventional color picture tube.

Now, FIG. 4 shows the state of the electron beam in a state where the electron beam is not deflected. Here, it is most preferable that the delay circuit 42 provides a constant delay time, and if the deflection magnetic field is formed in this way, a suitable result can be obtained. That is, in order to make the delay time variable, the delay circuit itself becomes complicated, and an additional circuit for controlling the delay circuit is required, which is undesirable from both a cost and technical standpoint. Therefore, in a color picture tube having an in-line array electron gun, for example, when a white grid is displayed on the screen and the delay circuit is not operated, the fifth
As shown in the figure, it is necessary that the positional deviations ΔX of the three colors R, G, and B are all the same on the entire screen. Furthermore, the fifth
In the figure, the horizontal lines are expressed as a single line, assuming that they match.

By the way, according to a 1957 paper by Johann, Hernthes, Gerritt, Jan, Ruthben et al., Philips, Research Report, Vol. 12, pp. 46-48, the convergence error is expressed as follows. This will be explained below with reference to the drawings.

Of the coordinate axes that are perpendicular to each other in Figure 6, Z
The axis indicates the axis of the picture tube, the positive Z direction indicates the traveling direction of the electron beam, and the X direction and Y direction each indicate the deflection direction of the electron beam. In FIG. 6, R,
G and B electron beams are generated from three electron guns respectively, R,
It is assumed that the light hits each of the G and B color phosphors, and that it has not yet been deflected at Z= _Z0 . Here, if the incident position of the electron beam at Z = Z ₀ is xs and ys at the X and Y coordinates, and the incident angles are xs' and ys' in the X and Y directions, respectively, then The deviations, that is, the deflection errors in the general sense Δx (x direction) and Δy (Y direction) are expressed as follows.

△x=A ₁・Xs ³ +(A ₂ +B ₃ )・Xs・Ys ² +(A ₄・Xs ² +B ₅ Y
s ² ) xs′++ (A ₆ +B ₆ ) ・Xs・Ys・ys′＋A ₇・Xs・xs′ ² ＋A ₈・Xs・ys′ ² ++
ZB ₈・Ys・xs′・ys′＋(A ₉ Xs ² ₊ B ₁₀ Ys ^{2 )} xs +(B ₁₁ +A ₁₂ )XsYsys ^＋＋ _{A 13
5} Ysxsys＋A ₁₆ Xs・xsxs′＋＋B ₁₇・Ys・ysxs′ ＋A ₁₈・Xs・ys・ys′＋B ₁₈ Ysxsys′ …(1-a) △y＝B ₁・Ys ³ +(B ₂ +A ₃ )Xs ²・Ys＋(B ₄ Ys ² +A ₅ Xs ² )
ys′ + (A ₆ +B ₆ )Xs・Ys・xs′＋B ₁ Ysys′ ² +B ₈・Ys・xs
′ ² ＋＋ZA ₈・Xs・xs′・ys′＋(B ₉・Ys ² +A ₁₀ Xs ² )
ys ++ (A ₁₁ +B ₁₂ )・Xs・Ys・xs＋B ₁₃・Ys・ys ² +B ₁₄ Y
sxs ² +A ₁₅ Xs・xs・ys＋＋B ₁₆・Ys・ys・ys′＋A ₁₇ Xs・xs・ys′＋B ₁₈ Ys・xs・xs′
…(1-b) However, An and Bn (n=1,…, 18) are the magnetic field strength function and deflection function, respectively, and Xs
is the magnitude of deflection in the X direction on the plane Z=Zs,
Ys is the magnitude of deflection in the Y direction on the plane Z=Zs,
Z ₀ and Zs represent the Z coordinate of the deflection start point on the tube axis and the Z coordinate of the screen position, respectively, and indicate the coordinate values shown in FIG. 6, respectively. Here, in the present invention, we mainly deal with the case where the R, G, and B3 electron beams are almost parallel, and since the R, G, and B3 electron beams are arranged in a straight line in the horizontal direction, xs'=0,
It is important to set ys′=0 and ys=0, and (1-a)
, Substituting these values into equation (1-b), △x=A ₁・Xs ³ +(A ₂ +B ₃ )・Xs・Ys ² ++(A ₉・
Xs ² +B ₁₀・Ys ² )・xs＋A ₁₃・Xs・xs ² …(2-a) △y=B ₁・Ys ³ +(B ₂ +A ₃ )・Xs ²・Ys＋＋(A ₁₁ +B ₁₂ )・XsYs・xs＋B ₁₄・Ys・xs ² …(2-b) Here, (2-a) and (2-b) In both equations, the first term,
The second term is a term representing linearity distortion and figure distortion, and is unrelated to the convergence term, so if it is excluded, △x=(A ₉ Xs ² +B ₁₀・Ys ² )・xs・A ₁₃・Xs・xs ²
…(3-a) △y=(A ₁₁ +B ₁₂ )・Xs・Ys・xs＋B ₁₄・Ys・xs ²
...(3-b)

However, when delaying using this method, it is extremely difficult to match the R, G, and B3 beams over the entire screen, so methods such as distorting the deflection magnetic field or attaching permanent magnet pieces to the deflection yoke are used. ing. Therefore, as a result, the magnetic field is also distorted, and the distortion of the beam spot still remains.
Furthermore, since permanent magnet pieces are used, the deviation of the deflection yoke is large, which is problematic from a practical point of view.

Further, US Pat. No. 2,764,628 discloses a color television in which multiple electron guns are formed in parallel when not deflected, but there is no mention of the deflection magnetic field, which is natural in such a system. Otherwise, a good screen will not be formed.

OBJECTS OF THE INVENTION In view of the above points, an object of the present invention is to provide a deflection yoke magnetic field having good convergence characteristics.

SUMMARY OF THE INVENTION The present invention provides a color picture tube that emits electron beams approximately parallel to the vertical deflection magnetic field HI0 on the tube axis.
The directional inclination H′ _I0 = dH _I0 /dZ, the horizontal secondary component HI2 of the vertical deflection magnetic field, and the Z-axis coordinate, which is the axis approximately coincident with the tube axis, with the origin at the deflection start point of the electron beam. When the forward direction is the positive direction and the screen surface position on these coordinates is Zs, the vertical deflection magnetic field is expressed in units of c・g・s−emu, |2・(Z−Zs)・H ₁₂ +H By setting ' _I0 |≦4.0 oersted per centimeter, the deflection error around the screen can be kept within the permissible range, and a color picture tube with less color shift and deflection distortion can be obtained.

Embodiments of the Invention First, each coefficient A ₉ of equations (3-a) and (3-b),
B ₁₀ , A ₁₃ ′A ₁₁ +B ₁₂ , B ₁₄ are expressed as follows.

A ₉ =2K∫ ^zs _z0 dS∫ ^s _z0 H〓 ₂・X／X _s ²・dz …(4) B ₁₀ ＝−K∫ ^zs _z0 dS∫ ^s _z0 H′ ₁₂・Y′／Y _s ² dZ− 2K∫ ^zs _z0 ds
∫ ^s _z0 H ₁₂・Y/Y _s ² dZ…(5) A ₁₁ +B ₁₂ =−2K∫ ^zs _z0 dS∫ ^zS _z0 H〓 ₂・Y/X _s・Y _s dZ−2K
∫ ^Zs _Z0 dS∫ ^S _z0 H ₁₂・X／X _s・Y _s dz＋＋K∫ ^Zs _Z0 H′〓 ₀・
_{X / _} ^_ _{_} ^_ _{_ _ _ _} ^_ _{_} ^_ _{_ _} /Y _s dZ+1/2K∫H′〓 ₀ /
Y _s dZ…(8) H〓 _X represents the strength of the vertical deflection magnetic field in the X direction in the plane where X=0, and is expanded to the power of y on the Y axis, as shown in the following equation (9). shown.

_{H〓 _ _} ^_ _{_ _} In the function, Z= _Z0 indicates the deflection start point, and Z=Zs indicates the Z coordinate of the deflection end point, that is, the screen position. Also, K is a proportionality constant, Y and Y' are Y=Y(z) and
The degree of deflection (trajectory) and deflection change (differential) of the beam in the Y direction are shown as Y'=dY/dZ, and when Z=Z ₀ , Y=Y'=0.

Further, H〓 _Y represents the strength of the horizontal deflection magnetic field in the Y direction in the plane where Y=0, and is expanded to the power of x on the X axis, and is expressed as the following equation (10).

H〓 _Y = H〓 ₀ +H〓 ₂・x ² +… …(10) However, H〓 ₀ : A function of Z, the zero-order coefficient of the horizontal deflection magnetic field on the tube axis, H〓 ₂ : Z's function, the quadratic coefficient of the horizontal deflection magnetic field
and X′ are respectively X=X(z) and X′=dX/dZ
Indicates the degree of deflection (trajectory) and change in deflection (differential) of the beam in the X direction, and in the case of Z=Z0, X=X′=
It is 0.

The subscripts and subscripts indicate the vertical deflection magnetic field and the horizontal deflection magnetic field, respectively. Xs and Ys are respectively the X of the beam at Z=Zs
and the Y coordinate position.

Note that H′〓 ₀ represents the differential of H〓 ₀ with respect to Z. That is, H′〓 ₀ = dH〓 ₀ /dZ.

Here, in order to make the deflection error zero, A ₉ ,
Since B ₁₀ , A ₁₃ , A ₁₁ +B ₁₂ , and B ₁₄ can all be set to zero, the conditions can be written out as follows.

Transforming equations (4) and (7) using partial integration, A ₉ =2K∫ ^Zs _Z0 dS∫ ^S _Z0 H〓 ₂・X/X _s ²・dz=−2K∫ ^Zs _Z0 (
Z−Zs）・H〓 ₂・X／X _s ² dz＝0…(11) A ₁₃ ＝K∫ ^Zs _Z0 ds∫ ^s _z0 H〓 ₂ /X _s dz＝−K∫ ^Zs _Z0 (Z−Zs)
・H〓 ₂ /X _s dz = 0...(12) In order for equations (11) and (12) to hold regardless of the amount of deflection of X, H〓 ₂ = 0...(13) must hold. That is, the horizontal deflection magnetic field must be uniform. However, in practice, there is no problem as long as it is substantially uniform, and it has been experimentally confirmed that there is almost no error if |H〓 ₂ |≦5.0 oersted per square centimeter. Then, the horizontal deflection magnetic field is said to be uniform. Using the condition of equation (13), B ₁₀ = −K∫ ^Zs _Z0 dS∫ ^S _Z0 H′〓 ₀・Y′／Y _s ²・dz−2K∫ ^Zs _Z
0 ds∫ ^S _Z0 H〓 ₂・Y／Y _s ² dz＝K∫ ^Zs _Z0 (Z−Zs) (H′〓 ₀
・Y′＋2H〓 ₂・Y)／Y _s ² dz=
0...(14) A ₁₁ +B ₁₂ =-2K∫ ^Zs _Z0 dS∫ ^S _Z0 H〓 ₂・X／X _s・Y _s dz＋K∫
^Zs _Z0 H′〓 ₀・X／X _s・Y _s dz＝K∫ ^Zs _Z0 2(Z−Zs)・H〓
₂ +H′〓 ₀ /X _z・Y _s・X.dz=0
…(15) What is important here is that in Figure 5, 51,5
2 and 53, the three colors R, G, and B are drawn as if they are the same in the horizontal direction, but in reality there is a considerable deflection error, and this deflection error is expressed as a △y error. . If such a Δy error exists, the delay circuit must provide a delay time for several horizontal deflection scanning lines. In addition, since the amount of △y changes depending on the amount of deflection, the delay time must be controlled variably, and the unit of this variable time is control over the number of scanning lines, so control is possible. The image quality also deteriorates significantly. However, such control is actually extremely difficult. In other words, it is clear that this method is not suitable for practical use because it causes discontinuities in the scanning lines and causes misalignment on the screen.

Therefore, it is especially essential that equation (15) holds true. Therefore, 2(Z-Zs)H〓 ₂ +H'〓 ₀ = 0...(16) must hold. What is particularly important in the convergence characteristics of a color picture tube of the present invention is the error Δy in the Y direction rather than the error Δx in the X direction. Therefore, the condition of equation (5) that does not involve Δy is not required in this case. Also, if equation (16) holds, equation (8) will also be transformed as follows, so at the same time
The condition of equation (8) is also satisfied.

B ₁₄ =−K∫ ^Zs _Z0 ds∫ ^S _Z0 H〓 ₂ /Y _s dz＋1/2K∫H′〓 ₀ /
Y _s dz = K/2∫ ^Zs _Z0 2(Z−Zs)H〓 ₂ +H′〓 ₀ /Y _s dz=0 In this case, it is clear from the above explanation that △y=0 and good convergence can be obtained. It is.

An example will be explained. In an actual color picture tube, the magnetic field is directly measured, and it is difficult to reduce the magnetic field obtained by equation (16) to zero within the measurement error. Therefore, as long as it is within the practical range for actual color picture tubes, it can be assumed to be approximately zero. Therefore, in the periphery of the screen in an actual color picture tube,
For 20-inch color picture tubes and larger tubes, an error of about 3 mm is acceptable as practical. Therefore, 20 inches
In a color picture tube with a 90° deflection tube and a distance between each electron gun of approximately 6.6 mm, |2(Z-Zs)・H〓 ₂ +H′〓 ₀ |≒3.7
It has been experimentally confirmed that the deflection error at the periphery of the screen is about 3 mm if the angle is approximately Oersted per centimeter. Therefore, in practical terms, if |2(Z−Zs)·H〓 ₂ +H′〓 ₀ |≦4.0 oersted per centimeter, a good screen with little color shift can be reproduced.

Preferably, the vertical deflection magnetic field is formed into a so-called pincushion type magnetic field on the incident side of the electron beam, and formed into a so-called barrel type magnetic field on the exit side.
Thereby, as an example, the condition of equation (16) can be approached, and good convergence can be obtained. This will be explained using drawings. 7th
Figure a shows an example of H′〓 ₀ , Figure 7 b shows (Z-Zs),
FIG. 7c shows H ₂ when the incident side of the electron beam is a so-called pink-tension type magnetic field and the exit side is a so-called barrel type magnetic field. In this case, the first term 2(Z-Zs)H〓 ₂ on the left side of equation (16) becomes as shown in Figure 7d, and the left side of equation (16) |2(Z-Zs)・H〓 ₂ +H′〓 ₀ | can be brought close to zero according to FIGS. 7a and 7d.

It has also been found that if the horizontal deflection magnetic field is formed into a so-called uniform magnetic field, a very good screen can be formed. By making the horizontal deflection magnetic field a so-called uniform magnetic field, it is possible to approach the condition of H〓 ₂ =0 in equation (13), and good convergence can be obtained.

Effects of the Invention As described above, according to the present invention, it is possible to obtain a color picture tube that uses substantially parallel electron beams and has less color shift and less deflection distortion without using complicated circuits or devices. can.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram for explaining a conventional color picture tube, Figure 2 is a schematic diagram for explaining the magnetic field distribution of a conventional color picture tube, and Figure 3 is a schematic diagram for explaining convergence error. Schematic diagram, Figure 4 is a schematic diagram of the configuration of a color picture tube using parallel electron beams, Figure 5 is a schematic diagram showing the screen of a color picture tube using parallel beams, and Figure 6 is the deflection error of the color picture tube. FIGS. 7a to 7d are conceptual diagrams for explaining the deflection magnetic fields of the embodiments of the present invention, respectively. 1...Face plate, 2...Fluorescent surface, 3...Shadow mask, 4...Mask frame, 5...Panel pin, 6...Spring, 7...Funnel, 8...Deflection yoke, 9...Net, 10...Electron gun, 11...For adjustment Magnet, 21... Screen periphery, 22... Horizontal deflection magnetic field,
23... Vertical deflection magnetic field, 31... Image, 32... Image,
41... Signal source, 42... Delay circuit, 43... Electron beam, 51, 52, 53... Grid image, 61, 62,
67, 70...Mask periphery, 63...Horizontal deflection axis, 6
4...Vertical deflection axis, 65...Horizontal deflection meridional concentration point,
66...Horizontal deflection sphere defective concentration point, 68...Vertical deflection sphere defective concentration point, 69...Vertical deflection meridian concentration point.

Claims (1)

[Claims] 1. In a color picture tube equipped with multiple electron guns arranged in a straight line and emitting electron beams almost in parallel, the horizontal deflection magnetic field is substantially uniform, and the Z-direction gradient of the vertical deflection magnetic field H _I0 on the tube axis H′ _I0 =dH _I0 /dZ
and the horizontal secondary component H _I2 of the vertical deflection magnetic field, with the origin being the deflection start point of the electron beam, the Z-axis coordinate being the axis that almost coincides with the tube axis, and the positive direction being the electron beam traveling direction. , when the screen surface position on such coordinates is Zs, the applied vertical deflection magnetic field is in units of c・g・s−e・m・u, |2・(Z−
Zs)・H _I2 +H′ _I0 | ≦4.0 oersted per centimeter.