JPS63294656A - Deflection yoke - Google Patents

Abstract

PURPOSE:To improve sea gull distortion in upper/lower distortion by providing a pair of magnetic substances on which magnets are mounted, on the side of a cathode-ray tube, thereby generating compensation electric fields in deflection electric fields. CONSTITUTION:One end polarity of one bipolar magnetic substance 10 mounted on one E-shaped magnet 9 is different to that of the other bipolar magnet 10' mounted on the other E-shaped magnet 9' in a face-to-face relation thereto. The combination of E-shaped magnetic substances 9, 9' and bipolar magnets 10, 10' form compensation magnetic fields shown by dotted lines. Electron beams are deflected due to the compensation electric fields such that upward forces act thereon in A and B portions while lower forces in C and D portions as shown by arrows 12, and no force in E and F portions. It is thus possible to improve sea gull distortion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a deflection yoke, and more particularly, to a deflection yoke that can selectively eliminate only Seagull distortion.

[Conventional technology] FIG. 6 is a sectional view of a conventional color cathode ray tube device.

In the figure, 50 is a color cathode ray tube, which is the part on which images are projected. The color cathode ray tube 50 consists of a panel 51, a substantially conical funnel 52 connected to the panel 51, and a tubular neck 53 connected to the funnel 52, which together form a vacuum vessel. ing.

An electron gun 54 is mounted inside the neck portion 53.

In the case of a color cathode ray tube, three electron guns 54 are arranged in parallel. A deflection yoke 1 is attached near the connecting portion between the funnel 52 and the neck portion 53. The electron beam 70 leaving the electron gun 54 is changed by the magnetic field generated by the deflection yoke 1 near point D, which is the effective center of the effective magnetic field, and travels toward a predetermined location on the panel 51.

The deflection yoke 1 has such a function.

A fluorescent film 55 is provided on the inner surface of the panel 51. Hereinafter, the surface on which the fluorescent film 55 is provided will be referred to as the inner effective portion 100.
shall be. Conventionally, the effective inner surface portion 100 has generally been a spherical surface that is convex toward the viewer.

In the inner surface effective portion 100, there is also a shadow mask 56 which has numerous regular small holes made of a thin metal plate that are convex in the same direction and are approximately parallel to the inner surface effective portion 100 and at a predetermined interval. are arranged. shadow mask 56
The outer periphery of the panel 51 is connected to a frame 57, which is a slightly thick metal plate, and is integrally attached to the inner surface of the panel 51 by a suitable holding mechanism (not shown).

The electron beam 70 deflected by the deflection yoke 1 passes through a small hole provided in the shadow mask 56 and impinges on a predetermined portion of the fluorescent film 55, causing it to emit light.

FIG. 7 is a structural external view of the deflection yoke shown in FIG. 6.

The deflection yoke 1 has a cylindrical core 2 made of a ferromagnetic material such as ferrite, and is used to generate a magnetic field for horizontally deflecting an electron beam, and is usually made from a tube-shaped winding. A pair of horizontal deflection coils 3 having a symmetrical shape to each other, and a pair of vertical deflection coils 3 having a symmetrical shape toroidally wound around the core 2, which generate a magnetic field for deflecting in the vertical direction. It consists of 4 coils. Note that the horizontal deflection coil 3 is sometimes wound toroidally around the core 2.

Now, in the conventional color cathode ray tube having the shadow mask 56 shown in FIG. 6, a phenomenon called local doming of the shadow mask 56 has become a problem. Local doming phenomenon means that the shadow mask 56, which normally has a convex surface facing the viewer, is locally heated and expanded due to the impact of the electron beam during operation, and becomes convex in the original direction. A phenomenon in which only the portion is deformed to become more convex, and the point of impact of the electron beam passing through the small hole on the phosphor film 55 is shifted from the originally desired position, resulting in undesirable color shift. say. Regarding this local doming phenomenon, please refer to the academic journal “Television” Vol. 31, No. 6,
A detailed discussion is provided on pages 46-52. and,
It has also been found that one of the most reliable countermeasures against this local doming phenomenon is to choose the radius of curvature of the shadow mass 56 as small as possible.

By the way, as described above, the aspect of the shadow mask 56 is determined in relation to the aspect of the inner surface effective portion 100 of the panel 51. Therefore, an effective means for reducing the radius of curvature of the shadow mask 56 is to first set the radius of curvature of the inner surface effective portion 100 to be small. However, what was originally a convex surface facing the viewer is now made even more convex, which changes the surface on which the image is projected to become less flat, making it as close to a flat surface as possible for easy viewing. This is not preferable from the standpoint of providing images.

In order to solve this problem, a method has been devised in which the surface of the inner surface effective portion 100 is made into a characteristic aspherical surface. Hereinafter, a panel having this characteristic inner surface effective portion will be referred to as an SP type panel.

The deflection yoke according to the present invention is particularly useful in eliminating the unique image distortion caused by the adoption of this SP type panel.

Therefore, below, first, the characteristics of this SP type panel and the image distortion caused thereby will be explained.

FIG. 8 is a diagram showing coordinate axes used for explaining the inner surface effective portion.

The inner surface effective portion 100 typically has a substantially rectangular shape.

In the following explanation, the central part of this plane (intersection with the tube axis of the color cathode ray tube 50) is set as the origin, two axes are provided so that the convex direction is positive, and the long sides of the rectangle are perpendicular to the two axes. An X-axis is provided in the direction, and a y-axis is provided in the short side direction. Normally, the X direction and the y direction correspond to the horizontal direction and the vertical direction, which are the two mutually perpendicular deflection directions of the deflection yoke 1, which were previously explained with reference to FIG. Therefore, deflection yoke 1
The positional relationship between the inner surface effective portion 100 and the inner surface effective portion 100 is as shown in FIG.

The case where the panel 51 is an SP type panel will be explained.

FIG. 10 shows a situation where the inner surface effective portion 100 is cut along the xz plane.

Since such a situation is usually created symmetrically, only the range of X≧O will be discussed below. When a cross section is represented by zf(x), and the radius of curvature at any X is Px, Px is represented by the following equation.

dχ2 When PX is positive, the cross section is convex in the +2 direction.

Now, when the X-axis end of the inner surface effective portion 100 is xffl, the sp panel is 2/3 Xma-x and 3/4
Comparing the xz cross-sectional curvature radius between Xff1Lx,
It can be said that it is characterized by having a portion with a smaller radius of curvature than Po.

By using the panel 51 having such a configuration, local doming can be reduced without significantly impairing the flatness of the screen. As described in the above-mentioned literature, local doming is a deformation phenomenon in a point portion where the deflection angle is small, that is, near the center of the inner surface effective portion 100.
Even if the deviation is large, the deviation of the beam projection point from the preferred position is relatively small and causes little actual damage. Also, the flatness near xmO is important for making the entire screen look flat, so P6
It is best to make it as large as possible.

Next, the last side of the screen xI? In this case, the shadow mask 56 is fixed to a frame 57 made of a fairly thick metal material, so local doming deformation is unlikely to occur, and even if deformation occurs, it will be at the periphery of the screen, making it difficult to view. The size of P is not very important because people do not pay much attention to it.

After all, in order to reduce local doming and the undesirable phenomena caused by it, the radius of curvature P We reach the conclusion that it is desirable to make , as small as possible (less than Po).

The above are the characteristics of the inner surface effective portion 100 of the panel, which is called an SP type panel in order to prevent local doming deformation.

Next, a diagram will be used to explain how an image is projected on the panel.

FIG. 11 shows a conventionally used inner surface effective portion 100.
This shows how an image consisting only of horizontal lines is projected onto a spherical panel.

In the figure, the image horizontal line 110 should preferably be projected parallel to the X-axis, as shown by the dotted line in the figure. However, when X is large, as shown in FIG.
As it goes from -0 to xffl, it gradually curves away from the X axis. Let us express the degree of this bending by the deviation Δy in the y direction from the y coordinate of each horizontal line at When, x2 is proportional to y.

Since the inner surface effective portion 100 is a spherical surface, the value of Δy becomes smaller as the radius of curvature becomes smaller. Further, the correction can be made to a certain extent by giving characteristics to the magnetic field distribution of the deflection yoke. Even taking these things into consideration,
Furthermore, although a bend may remain in the horizontal line 110, the situation is still that Δy is proportional to x2y, and if necessary, a simple distortion correction circuit can be added to the deflection circuit. It can be easily removed by

Next, FIG. 12 shows the degree of curvature of a horizontal line image when an SP type panel is used.

For the 5pyJ1 panel, xz of the inner surface effective part 100
Since the radius of curvature of the cross section has the characteristics described above,
The degree of change in the distance between the effective center point of the effective magnetic field of the deflection yoke 1 and the inner effective portion 100 differs from the vicinity to the outside (xllaX side) and the inside from the vicinity by X-2/3x. As a result, not only a term in which Δy is proportional to x2y, but also a phenomenon in which the horizontal line tends to curve rapidly toward the X axis from around X −2/ 3 X− occurs. Furthermore, in a more devised SP type panel, the cross-sectional shape in the plane parallel to the xz cross-section near the long sides (i.e., y m y , , x) of the inner surface effective portion 100 covers the entire screen. One way to make it look as flat as possible is to design it so that the width of change in two directions is suppressed. This means increasing the radius of curvature in this cross section as a whole, but since this part is the periphery of the screen, it is necessary to increase the radius of curvature in this section first. For the same reason as mentioned above, it is not a big problem as a local doming phenomenon.

In the end, in the vicinity of Y-Yffla)+, the phenomenon of bending toward the X-axis becomes rather light, and the conventional phenomenon of Δy being proportional to x2 y is removed, and the remaining symptoms become as shown in Figure 13. . The symptoms shown in FIG. 13 are hereinafter referred to as Segal distortion. Since the distortion Δy is a high-order function of It becomes something.

As shown in Fig. 14, the conventional general method for eliminating this seagull distortion is as shown in Fig. 14.
(beam exit) There is a method of arranging one permanent magnet 10 with polarity at the end flange part on each corner on the left and right sides. In FIG. 14, 2 is a ferrite core, 3 is a horizontal deflection coil, 4 is a vertical deflection coil, 8 is a separator, 8a is an end flange on the screen side, 8b is an end flange on the electron gun side, and 10 is a permanent magnet.

Next, the operation will be explained.

FIG. 15 is a diagram for explaining the operation of the permanent magnet 10. In the figure, 3 is a horizontal deflection coil, 8 is a separator, 10 is a permanent magnet, 70a, 70b, 70c, 70d,
70e,? Of represents the beam, and 12 represents the deflection force.

Next, the operation will be explained using FIG. 15.

By appropriately selecting the shape and dimensions of the permanent magnet 10, electron beams 70a, 70b, 70c, in which mainly the horizontal magnetic force line component of the loop-shaped magnetic force lines from the permanent magnet are deflected in the diagonal direction from the X-axis end. A deflection force 12 in the y-axis direction is applied to 70d. As a result, Seagull distortion is improved at the corners diagonally from the X-axis end of the screen. On the other hand, considering the effect of the mainly vertical magnetic field line component of the looped magnetic field lines, the beams 70e and 70f that are mainly deflected in the horizontal direction receive a force in the X-axis direction, that is, inward of the screen, and as a result, as shown in FIG. As shown in the figure, the left and right sides are generally bottle-cushion-shaped and locally concave.

This bottle cushion distortion occurs as it approaches the permanent magnet.
Since the distortion increases in a squared manner, if the bin cushion distortion is corrected at both ends of the screen using a conventional bin cushion distortion correction circuit, the vertical line near the center will conversely exhibit barrel distortion, and at the same time Conventional distortion correction circuits have the drawback of not being able to sufficiently correct distortion that is concave, resulting in only a compromise distortion correction.

[Problems to be solved by the invention] Since the conventional deflection yoke is configured as described above,
There is a problem in that even though the Seagull distortion in the upper/lower distortion is eliminated, side effects such as promotion of bin cushion distortion in the left/right distortion and generation of local dents are involved.

The present invention has been made to solve the above-mentioned problems, and it is possible to selectively eliminate Seagull distortion in the upper/lower distortion and perform distortion correction that minimizes the influence on left/right distortion. The purpose of the present invention is to provide a deflection yoke that provides a deflection yoke.

[Means for Solving the Problems] The present invention includes a panel having an effective inner surface portion provided with a fluorescent surface, a tubular neck portion in which three electron guns are disposed, the panel and the It is attached to a color cathode ray tube and has a funnel connecting the neck part, and a core made of a tubular ferromagnetic material, which is wound around the core and arranged in mutually symmetrical positions, and is emitted from the electron gun. a pair of horizontal deflection coils that generate a magnetic field for horizontally deflecting the electron beam emitted from the electron gun; and a pair of horizontal deflection coils that are toroidally wound around the core and for vertically deflecting the electron beam emitted from the electron gun. The present invention relates to a deflection yoke that is disposed near a connection between the funnel and the neck and includes a pair of vertical deflection coils that generate a magnetic field.

A pair of E-shaped magnetic bodies are arranged symmetrically to each other near the exit of the electron beam on the large diameter side, and the pair of E-shaped magnetic bodies are connected to a line connecting their axes. is the above 3
The electron guns are positioned so as to be parallel to the direction in which they are arranged, and the three legs of one E-shaped magnetic body face in the same direction as the three legs of the other E-shaped magnetic body. The body portion of the one E-shaped magnetic body is defined to face each other, and a bipolar magnet longer than the length of the body portion is provided on the back side of the opposite side to which the legs are attached. A bipolar magnet that is longer than the length of the body is attached to the back side of the body of the other E-shaped magnetic body opposite to where the legs are attached. The bipolar magnet attached to one E-shaped magnetic body is attached so that the pole at one end is different from the pole at one end of the bipolar magnet attached to the other E-shaped magnetic body facing it. It is characterized by

[Operation] Since the deflection yoke according to the present invention is constructed as described above, lines of magnetic force are emitted in the horizontal direction from the legs of the E-shaped magnetic material, so that the electron beam emitted by the electron gun is deflected by the lines of magnetic force. , Seagull distortion is improved.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a deflection yoke showing one embodiment of the present invention.

In the figure, 2 is a ferrite core, 3 is a horizontal deflection coil, 4 is a vertical deflection coil, 8 is a separator for holding each coil, 8a is a cross-sectional flange on the screen side, 8b
is the end flange on the electron gun side.

A pair of E-shaped magnetic bodies 9 are provided near the exit of the electron beam, which is the large diameter side of the deflection yoke, and are arranged symmetrically to each other. The pair of E-shaped magnetic bodies 9 are positioned so that a line connecting their axes is parallel to the direction in which three electron guns (not shown) are arranged. The directions of the three legs of one E-shaped magnetic body 9 are defined so as to face the three legs of the other E-shaped magnetic body. A bipolar magnet 10, which is longer than the length of the body, is attached to the body of one of the E-shaped magnetic bodies 9, on the back side of the opposite side to which the legs are attached.

The body part of the other E-shaped magnetic body 9', on the back side on the opposite side to which the legs are attached, has a length of 2 mm longer than the body part.
A polarized magnet 10' (not shown) is attached. The bipolar magnet 9 attached to one E-shaped magnetic body 9 has one end pole facing it, and the bipolar magnet 9′ attached to the other E-shaped magnetic body 9′ (
(not shown) so that the poles are different from each other.

FIG. 2 is a diagram for explaining the operation.

FIG. 2 is a cross-sectional view of the deflection yoke shown in FIG. 1 taken along a plane including a pair of E-shaped magnetic bodies.

In the figure, 3 is a horizontal deflection coil, 9 is an E-shaped magnetic body,
10 is a bipolar magnet, 8 is a separator, 70a,
7ob, 70e% 70ds 70e.

70f is an electron beam emitted from an electron gun (not shown).

The bipolar magnet 10 attached to the E-shaped magnetic body 9 has a pole at one end that is different from the pole at one end of the bipolar magnet 10'' attached to the other E-shaped magnetic body 9'' facing it. There is.

The combination of the E-shaped magnetic body 9 and the two-pole magnet 10 forms a correction magnetic field indicated by a broken line in the figure.

The electron beam is deflected by this correction magnetic field.

As is clear from the figure, an upward force as shown by arrow 12 is acting in portions A and B, a downward force as shown by arrow 12 is acting near C and D, and no force is acting near E and F.

FIG. 3 is a diagram when an image with only horizontal lines is projected on a cathode ray tube panel, and FIG. 4 is a diagram when an image with only vertical lines is projected on a cathode ray tube panel.

Both are diagrams when the deflection yoke according to the present invention is used.

In the figure, arrow 13 indicates the electromagnetic force that the electron beam receives due to the magnetic field component of the auxiliary coil, 14 (broken line) is the horizontal line of the screen before correction by the auxiliary coil, 15 (solid line) is the horizontal line of the screen after correction by the auxiliary coil, 16 (broken line) indicates a vertical line on the screen before correction using an auxiliary coil, and 17 (solid line) indicates a vertical line on the screen after correction using an auxiliary coil. The horizontal and vertical lines on the screen are corrected by the electromagnetic force 13 received by the auxiliary device, which is a feature of the present invention. By the above method, the Seagull distortion of the horizontal line can be corrected without locally worsening the Seagull distortion in the upper/lower dies.

In the above embodiment, as shown in FIG. 1, a case was explained in which a substantially E-shaped magnetic body and a bipolar magnet were paired and attached symmetrically to the flange surface of the screen side end surface of the separator. The present invention is not limited to this, but the same effect can be achieved even if the separator is attached to the screen-side side surface 8C of the separator as shown in FIG. In FIG. 5, the same or corresponding parts as in FIG. 1 are given the same reference numerals, and their explanations will be omitted.

Further, in the above embodiments, no consideration was given to the panel, but the effects of the present invention can be further enhanced by applying the present invention to the above-mentioned SP type panel.

[Effects of the Invention] Since the deflection yoke according to the present invention is configured as described above, the electron beam is changed by the magnetic lines of force coming out from the legs of the E-shaped magnetic body, so that Segal distortion of the horizontal line is improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view of one embodiment of the present invention, FIG. 2 is a diagram for explaining the operation, FIGS. 3 and 4 are diagrams for explaining the invention in detail, and FIG. 5 is a diagram for explaining the operation. A perspective view of another embodiment of the invention, FIG. 6 is a cross-sectional view of a color cathode ray tube, FIG. 7 is a structural external view of a deflection yoke, FIG. 8 is a coordinate axis used to explain the inner effective portion, and FIG. 9 is a deflection yoke. FIG. 10 is a cross-sectional view of the inner surface effective portion, and FIG.
Figure 1 is an image, Figure 12 is an image when using an SP type panel, Figure 13 is a diagram for explaining Seagull distortion, and Figure 14 is an image.
15 is a diagram illustrating a conventional improvement of the deflection yoke, FIG. 15 is an explanatory diagram of the operation, and FIG. 16 is a diagram illustrating bottle cushion type distortion. In the figure, 2 is a core, 3 is a horizontal deflection coil, 4 is a vertical deflection coil, 9 is an E-shaped magnetic body, 10 is a bipolar magnet, 50 is a color cathode ray tube, 51 is a panel, 52 is a funnel, and 53 is a neck part. be.

Claims (2)

[Claims] (1) A panel having an inner effective portion provided with a fluorescent surface, a tubular neck portion in which three electron guns are arranged, and a funnel connecting the panel and the neck portion. It is attached to a color cathode ray tube, and includes a core made of a tubular ferromagnetic material, and a core wound around the core and arranged in symmetrical positions to horizontally deflect the electron beam emitted from the electron gun. a pair of horizontal deflection coils that generate a magnetic field; and a pair of vertical deflection coils that are toroidally wound around the core and generate a magnetic field for vertically deflecting the electron beam emitted from the electron gun. a pair of E-shapes arranged in symmetrical positions near the exit of the electron beam on the large diameter side of the deflection yoke, which is arranged near the connection between the funnel and the neck part; The pair of E-shaped magnetic bodies have a line connecting the axes thereof to the three E-shaped magnetic bodies.
The electron guns are positioned so that they are parallel to the direction in which they are arranged, and the three legs of one E-shaped magnetic body face the three legs of the other E-shaped magnetic body. A bipolar magnet that is longer than the length of the body is attached to the body of one E-shaped magnetic body, and the back side of the opposite side to which the legs are attached. , a bipolar magnet longer than the length of the body is attached to the back side of the other E-shaped magnetic body on the opposite side to which the legs are attached; A bipolar magnet attached to the
A deflection yoke characterized in that the deflection yoke is attached so as to have a different polarity from one end of a bipolar magnet attached to the letter-shaped magnetic body. (2) The inner surface effective portion has a rectangular shape with one side parallel to the horizontal direction, and the normal line erected at the center of the inner surface effective portion is defined as the Z axis, and the Z axis passes through the center of the inner surface effective portion. , and a line parallel to the horizontal direction x
When the inner surface effective portion is cut along the xz plane defined as above, the radius of curvature x of the curve appearing on the cut is 2/3
At least at one point in the range of x_m_a_x to 3/4x_m_a_x (in the formula, x_m_a_x means the maximum value of x in the extension range of the inner surface effective portion), x = 0
2. The deflection yoke according to claim 1, wherein the deflection yoke is formed to have a value smaller than .