JP2571293B2 - Color cathode ray tube display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a color cathode ray tube display device, and more particularly, to a compensation coil for a magnetic field for canceling an external magnetic field acting in the tube axis direction of a color cathode ray tube. The present invention relates to a color cathode ray tube display device that generates automatically.

[Prior art] Cathode ray tube (Cathode Ray Tub) for displaying color images
e, hereinafter referred to as CRT) is also called a cathode ray tube, and is used in television receivers and the like.

The CRT scans a panel while deflecting an electron beam emitted from an electron gun by a magnetic field formed by a deflection yoke, and emits light on a panel coated with a phosphor to display an image.

For this reason, there is a problem that the image is easily affected by an external magnetic field, and when a magnetic field such as terrestrial magnetism acts on the CRT, the position on the panel to which the electron beam is irradiated changes, and a proper image cannot be obtained.

Therefore, the conventional color cathode ray tube display device,
In order to prevent the CRT from being affected by such an external magnetic field, a means for magnetically shielding the CRT by covering it with a cylindrical magnetic material is used.

However, the display panel of the CRT cannot be provided with a magnetic shield because an image is externally observed. For this reason, it is necessary to prevent the magnetic influence by the external magnetic field in the direction of the tube axis connecting the CRT panel and the electron gun.

Therefore, for example, as shown in FIG.
In the conventional example of Japanese Patent No. 33574, a magnetic compensating circuit for automatically generating a magnetic field for canceling an external magnetic field in the tube axis direction of the CRT by using a compensation coil is employed.

The magnetic compensation circuit in FIG.
(1), a magnetic detection element (2), and a current supply circuit (3)
And a compensation coil (24-1).

The CRT (1) includes an electron gun (1a) and a panel (1b), and a deflection yoke (5) is arranged around a funnel (1c) therebetween.

The magnetic detecting element (2) detects the polarity and strength of an external magnetic field in the tube axis direction of the CRT (1) and converts the detected magnetic field into an electric signal in accordance with the polarity and strength. As the magnetic detection element (2), a Hall element or the like is used.

The current supply circuit (3) receives an electric signal from the magnetic detection element (2) and supplies a current flowing in a direction corresponding to the polarity in proportion to the strength of the external magnetic field to the compensation coil (24-1). Is what you do.

The compensation coil (24-1) includes a current supply circuit (3)
When a current is supplied from the CRT (1), a compensation magnetic field for canceling an external magnetic field in the tube axis direction of the CRT (1) is generated. Here, the compensation coil (24-1) is connected to the panel (1) of the CRT (1).
b) It is wound around the periphery.

Next, the operation of this conventional example will be described with reference to FIG.

The polarity and strength of the external magnetic field in the tube axis direction of the CRT (1) detected by the magnetic detection element (2) are input to the current supply circuit (3) as an electric signal.

The current supply circuit (3) outputs a current flowing in a direction corresponding to the polarity in proportion to the strength of the external magnetic field by an electric signal, and supplies the current to the compensation coil (24-1). Thus, the compensation coil (24-1) can automatically generate a compensation magnetic field of the same polarity as the external magnetic field and of the opposite polarity, thereby canceling the influence of the external magnetic field.

For this reason, even when the installation position of the CRT changes and the polarity and strength of the external magnetic field such as the terrestrial magnetism change, the compensation magnetic field generated by the compensation coil (24-1) automatically follows this. The external magnetic field in the tube axis direction near the CRT can be canceled out.

By the way, the effect on the screen when a magnetic field acts in the direction of the tube axis of the CRT is to rotate and move the electron beam around the screen of the CRT. When the rotational movement of the electron beam is further analyzed, it can be divided into two, namely, rotation of the entire raster and rotation of purity.

FIGS. 3 (a) and 3 (b) are diagrams showing the effect of a magnetic field acting in the tube axis direction of a CRT on an image on a screen.
5 shows a screen state when a magnetic field is applied in the tube axis direction from the panel side to the neck side.

FIG. 7A shows a raster rotation, and FIG. 7B shows a purity rotation. This purity rotation is shown in FIG.
As shown in the figure, with respect to the phosphor (7) of the panel (1),
Electron beam (8) passing through a shadow mask not shown
Is rotated (here, clockwise) to cause mislanding as shown by the broken line. For this reason,
The electron beam (8) impinges only on the portion of the phosphor (7) indicated by oblique lines.

On the other hand, the effect on the screen generated by the compensation magnetic field formed by the compensation coil differs depending on the winding position of the compensation coil as shown in FIGS. 4 (a) and 4 (b).

For example, as shown in FIG. 4A, the compensation coil (24-2) is connected to the funnel (1) on the neck side of the CRT (1).
c) When it is wound around, a raster rotation as shown in FIG. 3A mainly appears, and the change in purity is small.

However, if the compensation coil (24-1) is wound around the panel (1b) of the CRT (1) as shown in FIG. Experiments confirmed that the purity rotation shown in FIG. 3 (b) appears simultaneously with the raster rotation shown in FIG. 3 (a).

[Problem to be Solved by the Invention] As described above, in the conventional CRT display device,
As shown in FIG. 4 (b), the external magnetic field acting in the direction of the tube axis of the CRT is compensated only by a single compensation coil wound around the panel of the CRT.

Since the compensation coil wound at this position generates a magnetic field that changes both the raster rotation and the purity rotation as described above, it is necessary to focus on either the purity rotation or the raster rotation to make the best adjustment. Or a compromise between the two.

The present invention has been made to solve the above-described problems, and automatically compensates both raster rotation and purity rotation generated by an external magnetic field in a tube axis direction acting on a CRT to an optimum state at the same time. It is an object to provide a color cathode ray tube display position capable of.

[Means for Solving the Problems] In order to solve the above problems, a color cathode ray tube display device of the present invention is wound around a panel of a color cathode ray tube, inputs a current from a current supply circuit, and controls a tube axis. A first compensating coil for generating a magnetic field for canceling the influence of purity rotation due to an external magnetic field in a direction, and a coil wound around a deflection yoke of a color cathode ray tube, and inputting a current from a current supply circuit to generate a tube shaft. A second compensating coil for generating a magnetic field for canceling the influence of the raster rotation due to the external magnetic field in the direction.

[Operation] The compensating coil of the color cathode ray tube display device according to the above means is composed of a first compensating coil having a function of compensating raster rotation and purity rotation, and a second compensating coil mainly having a function of compensating raster rotation. It consists of a coil.

Therefore, by appropriately selecting the number of turns and the like of each compensation coil, the purity rotation is compensated for by the first compensation coil using only the current from the same current supply circuit, and the remaining compensation is performed by the second compensation coil. Can be compensated for the raster rotation.

Accordingly, the color cathode ray tube display device of the present invention can automatically compensate both the raster rotation and the purity rotation generated by the external magnetic field in the tube axis direction of the CRT to the best state at the same time.

Hereinafter, a preferred embodiment of a color cathode ray tube display device according to the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a CRT display device according to one embodiment of the present invention. The CRT (1), the magnetic detection element (2) and the current supply circuit (3) in FIG. 1 are the same as those in FIG.

The characteristic configuration of the present embodiment is that, as shown in FIG. 1, a first compensating coil (4-1) is wound around the panel (1b) of the CRT (1) around the panel (1b). Are wound around the outer periphery of the panel-side separator flange (6) of the deflection yoke (5) of the CRT (1), and the current from the current supply circuit (3) is applied to each of the compensation coils. Is supplied.

The number of coil turns of the first compensation coil (4-1) and the second compensation coil (4-2) is determined as follows.

First, the first compensation coil (4-1) is a CRT (1)
Since it is wound around the panel (1b), it has both the purity rotation and the raster rotation compensation functions as described above. However, here, paying attention only to the purity rotation, the number of turns of the first compensation coil (4-1) is optimally selected so that the purity rotation is compensated by the current from the current supply circuit (3). I do.

Next, the second compensation coil (4-2) is a CRT (1)
The deflection yoke (5) is wound around the outer periphery of the panel-side separator flange (6), and thus has a function of mainly compensating for raster rotation as described above. Therefore, the second compensating coil (4--1) is compensated by the current from the current supply circuit (3) for the remaining raster rotation that could not be compensated by the first compensating coil (4-1). Determine the number of turns in 2).

In this way, the two compensation coils for which the number of turns has been determined are driven by the current supplied from the one current supply circuit (3) by the external magnetic field in the tube axis direction of the CRT (1) for the raster rotation and the purity rotation. Both can be automatically compensated for the best at the same time.

For the current supply circuit (3), the electrical connection between the first compensation coil (4-1) and the second compensation coil (4-2) may be either serial or parallel. You can also.

 Next, the operation of this embodiment will be described with reference to FIG.

First, the polarity and strength of the external magnetic field acting in the tube axis direction of the CRT (1) detected by the magnetic detection element (2) are converted into electric signals and input to the current supply circuit (3). In the current supply circuit (3), a current proportional to the strength of the magnetic field is supplied to the first compensation coil (4-1) and the second compensation coil (4) in response to an electric signal from the magnetic detection element (2). -2).

Since the first compensation coil (4-1) is wound with a predetermined appropriate number of coil turns, CR
A compensation magnetic field that cancels the purity rotation due to the external magnetic field in the tube axis direction of T (1) is generated.

Here, the first compensation coil (4-1) generates a raster rotation together with the purity rotation, but generates a raster rotation that could not be compensated because the number of coil turns is in accordance with the compensation of the purity rotation. A magnetic field remains.

Therefore, the second compensating coil (4-2) includes the first compensating coil (4-2).
A compensating magnetic field that cancels out a magnetic field that generates raster rotation that could not be compensated by the compensating coil (4-1).

Therefore, the color cathode ray tube display device of the present embodiment can simultaneously and automatically perform appropriate compensation for both raster rotation and purity rotation due to an external magnetic field in the tube axis direction of the CRT.

In other embodiments, when an external magnetic field is applied in the direction of the tube axis of the CRT, there is no need to compensate for the deterioration in screen quality due to raster rotation, although there is sufficient margin in purity. Sometimes you want to.

In such a case, a color cathode ray tube display device as shown in FIG. 2 can be employed.

The embodiment of FIG. 2 has almost the same configuration as the previous embodiment, but as shown in FIG.
Is wrapped independently around the outer periphery of the panel-side separator flange (6) of the deflection yoke (5).

The current from the current supply circuit (3) is supplied to the compensation coil (14-2) as in the previous embodiment.

 Next, the operation of this embodiment will be described with reference to FIG.

First, the compensation coil (14-2) wound around the outer periphery of the panel-side separator flange (6) of the deflection yoke (5)
The second compensating coil (4--) shown in FIG.
It has the same compensation function as 2). That is, a compensation magnetic field is generated mainly for the raster rotation, but has little effect on the purity rotation.

For this reason, when an external magnetic field acts in the tube axis direction of the CRT (1), there is a sufficient margin in purity, and when it is desired to compensate only for the deterioration of the screen quality due to the rotation of the raster, this embodiment Only the compensation by the compensation coil (14-2) is sufficient.

In this embodiment, since the winding position of the compensating coil (14-2) is on the outer periphery of the panel-side separator flange (6) of the deflection yoke (5) of the CRT (1), it is shown in FIG. Compensation coil around conventional CRT panel (24-1)
In comparison with this, the length of the coil for one turn can be made shorter and less copper material is required, so that the cost can be reduced.

Furthermore, since the separator flange (6) itself around which the compensating coil (14-2) is wound is an insulator, there is no need to newly insulate the compensating coil (14-2), and the cost of the insulating process is reduced. Can be reduced.

Further, in this embodiment, since no compensation coil is provided around the panel (1b), the size of the device itself can be further reduced.

In the above two embodiments, the compensation coil (4-2) shown in FIG. 1 or the compensation coil (14-2) shown in FIG. Has been described by winding around the outer periphery of the panel-side separator flange (6) of the deflection yoke (5), but it is not limited to the outer periphery alone, and may be in the vicinity. In this case, the same effect as above can be obtained.

The deflection yoke (5) used in the above two embodiments is a saddle-toroidal deflection yoke composed of a saddle-type horizontal deflection coil and a toroidal-type vertical deflection coil. It may be a yoke.

[Effect of the Invention] As described above, in the color cathode ray tube display device according to the present invention, the first compensation coil can compensate for the raster rotation and the purity rotation, and the second compensation coil mainly performs the raster rotation. Can compensate.

Accordingly, by appropriately selecting the number of turns of each compensation coil, both the purity rotation and the raster rotation due to the external magnetic field in the tube axis direction of the CRT can be automatically and simultaneously and optimally compensated.

[Brief description of the drawings]

FIG. 1 is a sectional view of a CRT display device according to one embodiment of the present invention, FIG. 2 is a sectional view of a CRT display device according to another embodiment of the present invention, and FIGS. FIG. 7A is a diagram for explaining an effect of a magnetic field acting in the direction of a tube axis of a CRT on an image on a screen, in which FIG.
FIGS. 4 (a) and 4 (b) are diagrams illustrating the nature of the compensation magnetic field generated by the difference in the winding position of the compensation coil, and FIG. 4 (a) and FIG. 4 (b) are diagrams illustrating the funnel on the neck side of the CRT. (B) is a diagram of a CRT wound around a panel. 1 and 2, (1) is a color cathode ray tube (CRT), (1a) is an electron gun, (1b) is a panel, (1c) is a funnel, (2) is a magnetic detection element, and (3) Is a current supply circuit, (4-1) is a first compensation coil, (4-2) is a second compensation coil, (14-2) is a compensation coil,
(5) is a deflection yoke, and (6) is a separator flange. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A color cathode ray tube for directing an electron beam emitted from an electron gun by a deflection yoke to display an image on a panel, and a polarity of an external magnetic field acting in a tube axis direction connecting the electron gun and the panel. A magnetic detecting element for detecting the strength, converting the electric signal into an electric signal, and outputting the electric signal; and a current supply for inputting the electric signal and outputting a current flowing in a direction corresponding to a polarity proportional to the strength of the external magnetic field A color cathode ray tube display device having a circuit, the first being wound around a panel of the color cathode ray tube, receiving a current from the current supply circuit, and generating a magnetic field for canceling an external magnetic field in a tube axis direction. And a coil wound around the deflection yoke of the color cathode ray tube, and receives a current from the current supply circuit to generate a magnetic field for canceling an external magnetic field in the tube axis direction. A second compensation coil that compensates for purity rotation due to an external magnetic field in the tube axis direction with the first compensation coil, and compensates for raster rotation with the second compensation coil. The number of turns of the compensating coil is set to the number of turns at which the purity rotation is compensated by the current from the current supply circuit, and the number of turns of the second compensating coil is the current from the current supply circuit. A color cathode ray tube display device, wherein the number of turns for compensating for the remaining raster rotation that cannot be compensated by the first compensation coil is set.