JPH0371541A - Image display device - Google Patents

Abstract

PURPOSE:To obtain an image display device wherein a magnetic leakage generated from a deflecting coil is cancelled out by providing near the outside of a deflecting yoke a pair of upper and lower reducing coils in parallel to the deflecting yoke. CONSTITUTION:A pair of upper and lower front end reducing coils 14a, 14b and a pair of upper and lower rear end reducing coils 15a, 15b, both of which pairs are in parallel to horizontally deflecting coils 9a, 9b, are provided on the front and rear sides of the horizontal deflecting coils 9a, 9b. A magnetic leakage generated by the front end and rear portion of the coils 9a, 9b is cancelled out by a magnetic field opposite to the magnetic leakage, generated by the reducing coils provided on the from and rear sides. Because the reducing coils 14, 15 are connected in series to the coils 9a, 9b, the time rate of charge of a current flowing through them is equalized to that of a deflecting current, so that the magnetic leakage is reduced more effectively. An image display device wherein the magnetic leakage is reduced is thus obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image display device, and more particularly to a device for reducing leakage magnetic fields generated from a deflection device of a cathode ray tube.

[Conventional technology]

FIG. 5 shows a schematic structure of a conventional cathode ray tube. , a funnel having a substantially conical shape; 5 is a neck portion made of a glass cylinder, and is connected to the funnel 4; 6 is an electron gun that generates at least one electron beam; 7 is a base that supplies various voltages for operating the electron gun 6; and 8 is a base that deflects the electron beam from the electron gun 6 to a required portion. It is a deflection yoke.

Here, the detailed configuration of the deflection yoke 8 will be explained using FIGS. 6 and 7 as an example.
are horizontal deflection coils 9a, 9b and vertical deflection coil 10a.
, iob, and the vertical coils 10a, 10
b is formed in a toroidal shape with a core 11. Further, the horizontal coils 9a and 9b are each loop-shaped and saddle-shaped, as shown in FIG.

Next, the operation will be explained.

In FIG. 5, the electron beam emitted from the electron gun 6 is guided to an appropriate position on the phosphor film 2 on the inner surface of the panel 3 by applying an appropriate deflection magnetic field from the deflection yoke 8, and is guided to an appropriate position on the phosphor film 2 on the inner surface of the panel 3. Project an image on the face of No.3.

Here, the detailed operation of the deflection yoke 8 will be explained as follows.
In order to deflect the electron beam emitted from the electron gun 6 in the vertical direction, as shown in FIG. Similarly, in order to deflect the electron beam horizontally, it is necessary to apply current to the horizontal deflection current coils 9a, 9b so as to generate an appropriate magnetic field in the vertical direction, that is, in the direction of 13a, 13b. It is necessary to apply a deflection current to the

Furthermore, as the above-mentioned deflection current, a sawtooth type alternating current is usually used, and the deflection current to the vertical deflection coil has a relatively low frequency of several tens of Hz, but the frequency of the deflection current to the horizontal deflection coil is relatively low. The current has a much higher frequency than in the case of the vertical deflection coil.

[Problem to be solved by the invention]

Conventional deflection devices for cathode ray tubes were constructed as described above, but recently there has been a great demand for higher image resolution and higher density display in cathode ray tubes, and as a means of achieving higher density display, The frequency of the horizontal deflection current has been increased, and specifically, in the current color TV system, the frequency of the horizontal deflection current is increased to 15.
Although the deflection current is 75 KHz, cathode ray tubes used in high-resolution displays require deflection currents at even higher frequencies of 31 KHz or 64 KHz. The deflection magnetic field generated by this high-frequency current not only deflects the electron beam inside the deflection yoke, but also occurs outside as a leakage magnetic field. The leakage magnetic field generated from the cathode ray tube has a problem that it not only has an adverse effect on nearby electronics, electric appliances, etc., but also has a harmful effect on humans, animals, etc., and cannot be ignored.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an image display device equipped with a cathode ray tube that can effectively reduce the leakage magnetic field generated from the deflection coil.

[Means to solve the problem]

The image display device according to the present invention is provided with a pair of upper and lower auxiliary coils arranged near the outside of the deflection yoke in parallel with the deflection yoke to cancel out leakage magnetic fields.

[Effect]

In this invention, a pair of upper and lower auxiliary coils are arranged near the outside of the deflection yoke of the cathode ray tube in parallel with the deflection yoke to cancel the leakage magnetic field, so that the leakage magnetic field generated from the deflection coil of the cathode ray tube is Therefore, it is possible to obtain an image display device with a small number of images.

〔Example〕

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

FIG. 1 is a schematic side view of a deflection yoke portion of an image display device according to an embodiment of the present invention, and FIG. 2 is a schematic view of the deflection yoke section viewed from the top in the y-axis direction shown in FIG. 1.

In the figure, 9a and 9b are horizontal deflection coils, which are loop-shaped saddle-shaped coils and are provided in an upper and lower pair. Further, front and rear end reduction coils 14a and 14b are provided in the form of loops, which form a pair vertically and parallel to the horizontal deflection coils 9a and 9b, and a rear reduction coil 15.
a and 15b are provided. Also, the reduction coil 14a.

14b, 15a, 15b are connected in series with the horizontal deflection coils 9a, 9b, as shown in FIG.
It is assumed that an alternating current having the same temporal change as that of the horizontal deflection coils 9a and 9b flows.

FIG. 4 is a diagram showing the relationship between the positions of the horizontal deflection coils 9a and 9b provided in the deflection yoke portion 8 of the cathode ray tube and the strength of the leakage magnetic field generated by the deflection magnetic field of the horizontal deflection coils 9a and 9b. , as shown in curve 16.

To explain in detail, the front end of the horizontal deflection coils 9a, 9b has a saddle-shaped opening larger than the rear end, and the leakage magnetic field to the outside generated therefrom is larger than that at the rear end. Moreover, since the core 11 is interposed on the outside of the intermediate portion of the horizontal deflection coils 9a and 9b, it is expected that the amount of leakage magnetic field to the outside will be relatively suppressed.

Therefore, in this embodiment, reduction coils 14a and 1 are used as auxiliary coils to reduce the leakage magnetic field as shown in FIG.
As shown in FIG. 4, 4b, 15a, and 15b are a location 16a in front and behind the deflection yoke 8 where the leakage magnetic field is expected to be large as described above.

16b. In addition, the reduction coil 14a
, 14b and 15a, 15b are wound to generate a magnetic field opposite to the leakage magnetic field generated from the deflection yoke 8, and are further connected in series with the horizontal deflection coils 9a, 9b. Note that the reduction coils 14a, 14b and 15
The size and shape of a and 15b are not particularly limited.

Next, the operation will be explained.

Before and after the horizontal deflection coils 9a, 9b, loop-shaped front end and rear reduction coils 14a, 14b and 15a, 15b are provided in pairs in parallel with the horizontal deflection coils 9a, 9b. The leakage field generated from the front and rear ends of 9b is canceled out by a magnetic field that is opposite to the leakage field emanating from the reduction coil. Further, since the reduction coil is connected in series with the horizontal deflection coils 9a and 9b, the deflection current has the same temporal change,
This more effectively reduces the leakage magnetic field.

In this way, in this embodiment, the leakage magnetic field is generated near the outside of the loop of the horizontal deflection coils 9a and 9b of the deflection yoke 8 of the cathode ray tube, and before and after the horizontal deflection coil, so as to form an upper and lower pair in parallel with the horizontal deflection coil. Front end and rear reduction coil 1 to reduce
4a, 14b and 15a, 15b, it is possible to reduce the leakage magnetic field generated from the horizontal deflection coils 9a, 9b of the cathode ray tube, and furthermore, the reduction coil 14a.

14b and 15a, 15b are the horizontal deflection coils 9a,
Since it is connected in series with 9b and a current having the same temporal change is applied, the leakage magnetic field can be reduced more effectively.

In the above embodiment, the reduction coils are provided before and after the horizontal deflection coil, but the arrangement of the reduction coils is not limited to this, and may be provided only at either the front or rear.

〔Effect of the invention〕

As described above, according to the image display device according to the present invention, near the outside of the horizontal deflection coil of the deflection yoke of the cathode ray tube,
A pair of upper and lower auxiliary coils that cancel out the leakage magnetic field are arranged parallel to this, making it possible to reduce the leakage magnetic field generated from the deflection coil of the cathode ray tube. There are effects that can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing a deflection yoke portion of an image display device according to an embodiment of the present invention, FIG. 2 is a schematic top view thereof, and FIG. 3 is an example of one connection of a coil in the deflection yoke of the device. 4 is a diagram showing the relationship between the position of each deflection coil and the strength of the leakage magnetic field in the conventional device, FIG. 5 is a diagram showing the schematic structure of the cathode ray tube in the conventional device, and FIG. FIG. 7 is a schematic diagram of the external appearance of the deflection yoke, FIG. 7 is a schematic diagram of the horizontal deflection coil of the deflection yoke, and FIG. 8 is a diagram showing the directions of magnetic fields generated from the horizontal and vertical deflection coils of the deflection yoke. l... Cathode ray tube, 2... Fluorescent film, 3... Panel, 4... Funnel, 5... Neck part, 6... Electron gun, 7... Base, 8... ...deflection yoke, 9a, 9
b...Horizontal deflection coil, 10a, 10b...Vertical deflection coil, 14a, 14b...Front end reduction coil, 15
a, 15b... Rear reduction coil, 11... Core. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In an image display device equipped with a cathode ray tube having an electron gun and a fluorescent screen inside and a deflection yoke outside, the deflection yoke includes a pair of upper and lower horizontal deflection coils, and an area near the outside of the coils. and a pair of upper and lower auxiliary coils arranged parallel to the auxiliary coil to form a pair and cancel out a leakage magnetic field generated by the horizontal deflection coil.