JPH0439840A - Deflection yoke device - Google Patents

Abstract

PURPOSE:To remove gal deformation or to re-form the deformation into a pin-cushion deformation by arranging a ringged magnetic body which is surrounding an electron beam path, and for which a coil of a toroidal shape is wound, in the vicinity of a deflecting yoke main body, and by letting run the current synchronized with a horizontal deflecting current waveform in the coil. CONSTITUTION:A ringged magnetic body 40 which is surrounding an electron beam path in the vicinity of a deflecting yoke 30, and for which a coil 41 of toroidal shape is wound, is arranged on the deflecting yoke 30, and the current having a certain relationship with a horizontal deflecting current is flown in the coil 41. The magnetic saturation of the core 40 is varied, and the vertical deflecting magnetic field formed on the periphery of the main body of the deflecting yoke 30 is varied thereby, and a raster deformation can be removed or re-formed into the deformation that can be easily removed according to a circuit. The removal of a gal deformation, or reformation thereof into a pin-cushion deformation can thus be achieved.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a deflection yoke device used for a color cathode ray tube,
In particular, the present invention relates to a deflection yoke device equipped with a raster distortion control device.

[Conventional technology]

FIG. 7(a) is a schematic cross-sectional view of a color cathode ray tube including a conventional deflection yoke device.

In the figure, 1 is usually a color cathode ray tube body made of non-magnetic material and has a vacuum inside.
It consists of three parts: a, funnel lb, and neck tube IC. A fluorescent film 2 is provided on the inner surface of the panel 1a, and a large number of through holes are regularly provided inside the fluorescent film 2 at an appropriate distance from the fluorescent film 2, and color selection electrodes 3 generally made of metal are provided. is located.

The funnel 1b represents a conical portion connected to the panel 1a, followed by a thin cylindrical neck tube 1c. An electron gun 10 that generates an electron beam 20 is arranged on the other end side of the neck tube 1C.

As shown in the cross-sectional view of FIG. 2B, the electron guns 10 generally include three electron guns 10a arranged in a horizontal direction.

10b, IOC, one of which is 10b
is arranged exactly to coincide with the central axis of the color cathode ray tube body 1, that is, the axis of the neck tube IC. Further, a deflection yoke 30 is arranged near the junction between the funnel lb and the neck tube IC of the color cathode ray tube body 1.

Next, the operation will be explained.

The electron beams 20 (20a, 20b, 20C) emitted from the electron gun 10 (10a, 10b, 10c) are deflected at a predetermined angle by the action of the magnetic field of the deflection yoke 30, and are directed through the holes of the predetermined color selection electrodes 3. The light passes through and hits the fluorescent film 2, causing it to emit light.

By the way, this deflection yoke 30 is a magnetic field generating device having a coil for bending the electron beam 20 using an electric current so that the electron beam 20 departs from the electron gun 10 and hits a desired position on the fluorescent film 2. , is an auxiliary part installed near the connection between the funnel 1b and the neck tube IC, and as shown in FIG. 8, the core 31. Horizontal deflection coil 32.
The core 31 is made of a substantially cylindrical high-permeability ferrite, and the horizontal deflection coil 32 is usually a pair of saddle-shaped coils fitted inside the core 31. 20 in a horizontal direction, that is, in a direction parallel to the direction in which the electron guns 10a, 10b, and 10C are lined up, a magnetic field is distributed in a substantially vertical direction, that is, in a direction perpendicular to the horizontal direction, by a horizontal deflection current. occurs near the space surrounded by the core 31.

On the other hand, the vertical deflection coil 33 is typically composed of a pair of toroidal coils wound around the core 31 in a toroidal manner. A magnetic field distributed around the core 31 is generated in the vicinity of the space surrounded by the core 31.

In order for such a color cathode ray tube to operate satisfactorily, various conditions are required. Regarding the deflection yoke 30, first of all, the three electron beams emitted from each of the electron guns 10a, 10b, and 10c are Electron beams 20a, 20b,
No matter which direction the light is deflected by the deflection yoke 20c or the deflection yoke 30, it is necessary to always concentrate it on the fluorescent film 2.

A state where this concentration effect is incomplete is called misconvergence, but the deflection magnetic field generated by the deflection yoke for recent color cathode ray tubes has a special distribution, and efforts have been made to prevent misconvergence from occurring over the entire surface of the phosphor film. is being done.

Second, when an image that is supposed to consist of a group of mutually orthogonal parallel straight lines in a checkered pattern is displayed on a fluorescent film, it is necessary that the image be accurately projected as a set of parallel straight lines. This means that when the vertical deflection current for the vertical deflection mentioned above is kept constant and only the horizontal deflection current is changed, the electron beam 20
, typically, the locus of the projection point drawn by the centrally located 20b on the fluorescent film 2 is a horizontal straight line that is parallel to the fluorescent film 2 when viewed from a sufficiently distant front, regardless of the value of the vertical deflection current. When the horizontal deflection current for horizontal deflection is kept constant and only the vertical deflection current is changed, the locus of the impact point drawn by the electron beam 20b on the fluorescent film 2 is the value of the horizontal deflection current. Regardless, it means parallel vertical straight lines.

This characteristic is called the raster shape characteristic of the deflection yoke, and as mentioned above, the phenomenon in which straight lines that should be parallel do not become parallel is called raster distortion. Attention has been paid to the raster shape characteristics, and the distribution of the deflection magnetic field has been appropriately devised.

As described above, it is desirable for the deflection yoke to simultaneously obtain both the coherence characteristic and the raster shape characteristic.

As a result of the analysis, what is important for the convergence characteristics is the magnetic field distribution on the entrance side of the deflection yoke 30, that is, on the electron gun 1o side, and what is important for the raster shape characteristics is the magnetic field distribution on the exit side of the deflection yoke 30, that is, the magnetic field portion of the two fluorescent films. . However, in the conventional deflection yoke of 3 degrees, by designing the magnetic field distribution on the entrance side and the exit side to be adjusted and considered independently to a certain extent, both of the above characteristics could be made practically satisfactory to a considerable extent.

However, in recent years, for large-sized, high-definition image tube devices with large deflection angles for HDTVs, the requirements for both characteristics have become much stricter than for conventional devices. It has become difficult to satisfy both of these characteristics at the same time. This means that even though convergence characteristics are dominated by the influence of the magnetic field distribution on the entrance side of the deflection yoke 30, in reality there is also an influence on the exit side, and this cannot be ignored.Therefore, the requirements for both characteristics are As the situation becomes more severe, it becomes more difficult to deal with the problem of interference between the two.

Therefore, a method is used to control both of the above characteristics without interfering with each other as much as possible. For example, in the case of convergence characteristics, an auxiliary magnetic field generator having a small auxiliary coil is provided on the entrance side of the deflection yoke 30, and a current synchronized with the horizontal or vertical deflection current is passed through this to obtain more perfect convergence characteristics. A method called dynamic convergence is known, and although this method does not eliminate interference with raster distortion characteristics, if the position of the auxiliary magnetic field device is adjusted, interference between both characteristics can be considerably separated. is possible.

In addition, the raster shape characteristics do not make the horizontal and vertical image deflection currents a mere sawtooth wave, but rather cause them to interfere with each other and cause the amplitude of the horizontal deflection current to change with the vertical deflection current value, or cause the horizontal deflection current to be included in the vertical deflection current. Improvements have been made by modifying the deflection current generation circuit (this is called a raster distortion correction circuit), such as by creating a small ripple synchronized with the current.

[Problem to be solved by the invention]

The conventional deflection yoke device is configured as described above.
Each of the above-mentioned devices requires a current generating device with a complicated waveform. This current is created based on either horizontal or vertical deflection current (voltage), but these are originally sawtooth waves, so if you try to shape them with a simple passive circuit, the range of waveforms that can be stably obtained is limited. Even with the use of these auxiliary devices, it is difficult to completely solve the problem. Note that although it is possible to use an active circuit such as a transistor or a waveform storage circuit with a memory, it is not so preferable because it causes cost reduction and various stability problems.

However, if you try to solve the problem without using complicated auxiliary equipment, and look at the problems in various cases, you will find that the remaining problems can be reduced to limited patterns of misconformity or raster distortion. . If this is summarized as a problem of raster shape characteristics, the typical raster distortion pattern that causes the most problem is as shown in FIG.

To be more specific, FIG. 9 is a view of the panel 1a and the fluorescent film 2 viewed from the outside front of the cathode ray tube.Hereinafter, the intersection of the central axis of the cathode ray tube and the fluorescent film 2 will be defined as the origin 0, and on this fluorescent film 2, The x-axis is in the horizontal direction, that is, the direction in which the electron guns 10a, 10b, and 10c are lined up, and the y-axis is in the direction perpendicular to this.
The axes are defined as shown in the figure, and the intersection of the outer peripheral line of the fluorescent film 2 with the x-axis is defined as X, and the intersection with the y-axis is defined as Y. Furthermore, since the problem we are about to discuss is symmetrical with respect to both the x and y axes, except in special cases, only the first quadrant on the fluorescent film 2 where x and y≧0 will be considered. When considering the raster shape characteristics, it is sufficient to consider only the image generated by the electron beam 20b emitted from the central electron gun 10b.

Now, the raster distortion pattern in question is a horizontal line figure too
(line parallel to the x-axis) x-3/4X.

The part from the vicinity to X = X H is not a continuous extension of the part from X = O to 3/4
This refers to the phenomenon of bending in the direction of smaller.

In the top view, the section from X=O to 3/4X of the horizontal line figure 100 is also drawn slightly curved in the direction of decreasing y, but this section can also be curved as shown in the figure. The section may be a straight line, and the condition of this section is not necessarily important in terms of the nature of the present invention, which will be described below.

The amount of curvature in the direction of smaller y is compared to a simple extrapolation value (usually based on a quadratic expression of X) of a figure whose y coordinate of the horizontal line image is from X=O to The amount of deviation from this can be discussed in terms of the value Δy measured at x=X.

Generally, when there is a raster distortion pattern in which Δy≠0, an image that should originally be a straight line looks like the shape of the wings of a seagull (gull) when it is gliding, so it is called gull distortion.

One of the ways to solve this Gal distortion is to transform it into so-called pink distortion as shown in FIG. 10, which can be easily removed or corrected using a deflection circuit. becomes a parabolic figure symmetrical about the y-axis, and this horizontal line image 100 is expressed as y=f
(x)+Yo (where Yo is the intersection of this horizontal line image 100 with the y-axis) d''/ When the door becomes larger, the larger X becomes.

Here, if it is possible to transform the gull distortion shown in Figure 9 into the binction distortion shown in Figure 10, the remaining bin distortion can be relatively easily removed using a method commonly known as an upper and lower bin distortion correction circuit. In view of the above circumstances, it is an object of the present invention to provide a deflection yoke device that is equipped with a device that can eliminate gal distortion or transform it into binkction distortion.

[Means to solve the problem]

The deflection yoke device according to the present invention includes a deflection yoke having a conventional structure, in which an annular magnetic body surrounded by an electron beam path is disposed adjacent to the deflection yoke, and a toroidal coil coil is wound around the deflection yoke. Furthermore, a current having a certain relationship with the horizontal deflection current is caused to flow through this coil.

[Effect]

The deflection yoke device according to the present invention surrounds the electron beam path in the vicinity of the deflection core, and arranges an annular magnetic body around which a toroidal coil is wound. Since we made a current with a certain relationship flow, the magnetic saturation of the core changes, which changes the vertical deflection magnetic field created around the deflection yoke body.
Raster distortion can be removed or transformed into something that can be easily removed by a circuit.

〔Example〕

FIG. 1 shows a schematic diagram of a deflection yoke device according to an embodiment of the present invention. The same reference numerals as in FIG. Annular cores 40 are arranged at appropriate distances. The core 40 is made of a material having high magnetic permeability and subject to magnetic saturation, such as an alloy containing nickel and iron, and is an annular body having a relatively small cross section. Further, in order to maintain the shape of the annular core 40 and prevent the generation of overcurrent due to the coil current described later, it is preferable that the annular core 40 be formed by, for example, winding and bundling mutually insulated thin magnetic wires.

A coil 41 is wound toroidally around the entire circumference of the core 40, and this coil 41 is further connected to a waveform generator 42 that supplies a current synchronized with a horizontal synchronization signal.

Note that a device for fixing the core 40 in a predetermined position is not shown.

Next, the operation will be explained using FIG. 2.

This figure shows a schematic view of the deflection yoke device shown in FIG. 1 above when it is attached to the color cathode ray tube main body 1 when viewed from the vertical direction (y direction).

During its operation, the deflection yoke 30 generates vertically deflected leakage magnetic flux 101 in the forward direction. Normally, this leakage magnetic flux is generated in a direction that contributes to the vertical deflection of the electron beam. Some of this magnetic flux 101, like 101a, is generated so as to enter the core 40. As mentioned above, the core 40 is made of a material with high magnetic permeability, so when no current i flows through the coil 41, magnetic flux such as 101a passes through the core 40 and contributes to vertical deflection. However, when a current flows through the coil 41 and this current i exceeds a certain value, the core 40 is magnetically saturated by this current, and the magnetic flux 101a can no longer pass through the core 40, and the magnetic flux 101b As?・This occurs in the space in which the electron beam travels as magnetic flux that contributes to deflection. That is, when the current i is large, the sensitivity of the vertical deflection is improved, and the electron beam can be largely deflected in the y direction for the same vertical deflection current as in the past. If generated and applied to the coil 41, raster distortion can be corrected to a considerable extent, or it can be transformed into a pattern that is easy to correct using a distortion correction circuit or the like.

An example of the waveform generating circuit 42 is shown in FIG. In the figure, 43 is a horizontal deflection output circuit, which is a general circuit for passing current through the horizontal deflection coil 32. A part of this output is passed through a full-wave rectifier circuit configured as shown in the figure using four diodes 44, and the current waveform is shaped by the coil 41.
is supplied to.

Next, the operation of this waveform generating circuit 42 will be explained.

In this circuit, if the diode 44 does not exist and the output of the horizontal deflection output circuit 43 is directly connected to the coil 41,
A current as shown in FIG. 4(a) will flow through the coil 41 (in the figure, Xn, O, and XM are relative X coordinates of the point where the deflected electron beam strikes the fluorescent film 2). ), but by inserting a full-wave rectifier circuit using diodes as shown in Figure 3, theoretically half of the waveform should be folded back and a current as shown in Figure 3) should flow. . However, the diode 44 has a threshold voltage, and even if the voltage applied across the diode 44 is in the forward direction, no current will flow if it is below a certain value. Therefore, in reality, as shown in the same figure (C), no current flows in the coil 41 near the 0 point (the part where the amount of deflection in the X direction is small), but when the amount of horizontal deflection l Current will flow.

On the other hand, the core 40 has relatively steep saturation characteristics.

Therefore, if the number of turns of the coil 41 and the threshold voltage of the diode 44 are appropriately selected according to the characteristics of the core 40, the core 40 will start to saturate when the horizontal deflection amount lxl is around lXl = 3/4XM. , l X l > 3/4X, the magnetization state of the core 40 can be controlled so that it gradually approaches complete saturation as lxl increases;
If the amount of vertical deflection is large, the magnetic flux 101b contributing to the vertical deflection as explained earlier in FIG.
X, and the amount can be increased as lxl increases. In other words, by correcting the sagging of the horizontal line that occurs at the IX > 3/4 part of the Gull distortion as shown in Fig. 9, it can be corrected with a simple distortion correction circuit, as shown in Fig. 10. It can be transformed into a pin distortion.

Here, the reason why the full-wave rectifier circuit using the diode 44 is used is that in addition to controlling the current using the threshold voltage, it also controls the vertical deflection magnetic flux when the electron beam scans any quadrant on the fluorescent film 2. The relationship of addition and cancellation between the leakage magnetic flux such as 101a passing through the core 40 and the magnetic flux generated in the core 40 by the current 1 is always constant, and the distortion correction amount is uniform in all four quadrants. When the amount of distortion correction is small and can be ignored even if there is some difference between the quadrants, full-wave rectification is used to balance the quadrants. The circuit can also be omitted.

Therefore, for example, if the purpose is only to control current using a threshold voltage, it is possible to use a current waveform generating circuit 42 as shown in FIG. 5 using two diodes 44, and depending on the form of distortion, Practically satisfactory distortion correction characteristics can also be obtained by appropriately selecting only the characteristics of the core 40 and the number of turns of the coil 41 and removing the diode 44. In such a case, it is of course possible to connect the coil 41 and the horizontal deflection coil 32 not only in parallel but also in series.

Figure 6 shows the core 4o and coil 41 of Figure 1 or Figure 2.
FIG. 2 is a diagram seen from the fluorescent film 2 side.

Now, if a vertical deflection magnetic field is generated and its leakage magnetic flux 101 is generated in the left direction, that is, in the -X direction as shown in the figure, the electron beam will be deflected upward, that is, in the +yX direction. Therefore, the saturation characteristic of the core 4o has the most influence on the deflection of the electron beam at its +y end. Therefore, when a current waveform generating circuit having a full-wave rectifier circuit as shown in FIG. If the magnetic flux 102 generated in a circular manner by the current i is oriented in the -X direction, the normal Gull distortion, that is, the distortion in which Δy increases as y increases, can be efficiently corrected. Note that when the leakage magnetic flux 101 accompanying the vertical deflection magnetic field is directed in the opposite direction to that shown in the figure, the electron beam is deflected in the -yX direction, so the situation is the same.

If the circulating magnetic flux 102 generated by circulating in the cal core 4o is opposite to that shown in FIG. Rather, it decreases as the leakage magnetic flux 101 increases.

That is, even if the vertical deflection amount y increases, the correction amount of Δy does not increase much.

This makes it possible to correct what is known as the so-called intermediate gull distortion, in which the ratio of Δy is rather high in a portion near the X-axis as shown in FIG. Note that this intermediate gal distortion often becomes a problem when the panel 1, which has been frequently used in recent years, has a certain type of aspherical surface.

By the way, when a magnetic circuit synchronized with the horizontal deflection is placed in the vertical deflection magnetic path as shown in Fig. 2, undesirable interference occurs between the two, and a type of parasitic oscillating current called ringing often occurs on the screen. The configuration of the annular core 40 and toroidal coil 41 according to the present invention allows the magnetic flux (vertical The interference between the deflection magnetic flux) and the magnetic flux generated by the coil 41 is
The things that occur in each quadrant always cancel each other out, and as a result, mutual interference becomes zero, and this problem does not occur.

Furthermore, in general, when a current synchronized with the horizontal deflection is passed through such an auxiliary coil device, the coil itself tends to generate magnetic flux in the space outside the cathode ray tube with time variations that are undesirable from the standpoint of unnecessary radiation and electromagnetic environment. However, in the present invention, the magnetic flux produced by coil 41 is always substantially confined within its toroidal shape, and such problems are largely negligible.

Now, in the embodiment described above, the core 40. The coil 41 is placed in front of the deflection yoke 30 to control the raster distortion, but as a result, the distribution of the deflection magnetic field is changed, so even though the raster distortion pattern is changed, the However, in the present invention, the location where the deflection magnetic field is changed is far in front of the main body of the deflection yoke 30, and in this case, the raster distortion occurs in the front of the deflection yoke as described above. According to the principle that the rear side has a large influence on the convergence characteristic, this corresponds to a fairly extreme case, and the degree of change in the convergence characteristic is very small compared to the degree of change in the raster distortion characteristic. This can be recovered sufficiently by slight adjustment of the line distribution using a well-known method, and there is almost no problem in practical use.

Note that the core 40 of the deflection yoke device of the present invention. coil 41
The method of arranging the auxiliary magnetic field generator consisting of the core 40. The coil 41 does not necessarily need to be placed in front of the deflection yoke 30.

For example, as shown at 103 in FIG. 2, leakage magnetic flux also exists behind the deflection yoke 30. Furthermore, when the vertical deflection coil has a toroidal shape as shown in FIG. 8, leakage magnetic flux also occurs on the outside of the cylindrical side surface. Therefore, the core 40 of the present invention is attached to the rear of the deflection yoke 30 (on the side closer to the electron gun 10) or the outer circumference of the deflection yoke 30. A coil 41 may also be arranged.

In this case, the current flowing through the coil 41 will not only affect the raster distortion characteristics (but also the convergence characteristics), but the installation of the device of the present invention increases the degree of freedom in designing the deflection yoke magnetic field. However, as long as the main body of the deflection yoke 30 is designed accordingly, that is, if this degree of freedom is fully utilized, it may sometimes be more convenient than attaching the device to the front of the deflection yoke 30. be.

In the explanation of the above embodiment, it has been stated that the horizontal deflection is of equal period and that the current i flowing through the coil 41 is synchronized with the horizontal deflection current, but more essentially the t current i is the electron current on the fluorescent film 2. It suffices if it is a function of the beam impact position X, that is, the horizontal deflection current,
Therefore, it is only necessary that the current i changes in a specific relationship with the horizontal deflection current. That is, the application of the present invention is not necessarily limited to deflection yokes of the raster scanning method, but can also be applied to the so-called stroke drawing method.

Furthermore, in the above embodiment, it has been described that the Gull distortion is removed or the distortion is transformed into a pincushion distortion, but depending on the situation in the section from X=O to 3/4X of the image shown in FIG. Needless to say, it is possible to obtain satisfactory raster distortion characteristics with the device alone, and even without the use of a binction distortion correction circuit.

Furthermore, although the core 40 has a circular shape in the above embodiment, the shape of the core 40 is not limited to this.

〔Effect of the invention〕

As described above, according to the deflection yoke device according to the present invention, an annular magnetic body formed by winding a toroidal coil surrounding an electron beam path is arranged near the deflection yoke main body, and a horizontal deflection current is applied to this coil. By passing a current that is synchronized with the waveform, the conventionally complicated gal distortion can be eliminated.
This has the advantage that it can be relatively easily corrected or transformed into a pattern that is easy to correct using another method, thereby improving the quality of color cathode ray tube images.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a deflection yoke device according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional diagram of a deflection yoke device according to an embodiment of the present invention, and FIGS. 2 is a circuit configuration diagram of the current waveform generation circuit, FIG. 4 is a diagram for explaining the current waveform of the current waveform generation circuit of FIG. 3, and FIG. 6 is a circuit diagram of the current waveform generation circuit of FIG. A diagram for explaining the operation of the coil and core of the deflection yoke device according to the embodiment, FIG. A diagram for explaining the electron gun in detail, FIG. 8 is a schematic diagram of a conventional deflection yoke device,
FIGS. 9 to 11 are diagrams for explaining raster distortion. 1...Color cathode ray tube body, 1a...Panel, 1
b... Funnel, 1c... Neck tube, 2... Fluorescent film, 3... Color selection electrode, 10 (10a, 10b,
10c)...Electron gun, 20 (20a, 20b, 20
c) -Electronic beam, 30...deflection yoke, 31...
Core, 32... Horizontal deflection coil, 33... Vertical deflection coil, 40... Annular core, 41... Annular coil,
42... Current waveform generation circuit, 43... Horizontal deflection output circuit, 44... Diode, 100... Horizontal line image, 101, 103... Leakage magnetic flux, 102... Circulating magnetic flux. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A deflection yoke body disposed in the path of the electron beam and having a horizontal deflection coil and a vertical deflection coil for deflecting the electron beam; and a deflection yoke body disposed near the deflection yoke body surrounding the path of the electron beam. an annular core made of a saturable magnetic material, a coil wound in a toroidal manner to generate surrounding magnetic flux in the annular core, and the coil having a certain relationship with the current flowing through the horizontal deflection coil. A deflection yoke device comprising a waveform generation circuit that supplies current.