JPH01154442A - Cathode-ray tube display device - Google Patents

Abstract

PURPOSE:To prevent a reduction in life and an increase in weight due to an increase in temperature in internal electronic circuits by winding a cancel coil along the circumferential direction of a magnetic shield member provided along the openly diffusing surface of a funnel section. CONSTITUTION:A device is equipped with a cathode-ray tube 1 provided with a magnetic shield 8 on the openly diffusing surface of a funnel section 16, with a circular coil approximately in a cylindrical form to be fixed on the narrow section of the aforesaid cathode-ray tube 1, with horizontal coils 3 and 4 provided along the inner circumferential surface of the circular core 2, with a vertical coil wound by the circular core 2, and with cancel coils 21 and 22 wound along the circumferential direction of the magnetic shield member 8. And horizontal deflection current or its high frequency current is applied to the concel coils 21 and 22 in such a way that a magnetic field induced from the front side of the horizontal coil is concelled or reduced. This constitution thereby can prevent a reduction in life and an increase in weight due to an increase in temperature in internal electronic circuits.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is an improvement of a cathode ray tube display device that electromagnetically deflects a high-energy electron beam when a cathode ray tube (hereinafter referred to as CRT) uses a high-energy electron beam. It is related to.

[Conventional technology]

Figure 4 shows, for example, "rNHK color television reception technology" P19
4 (published by Japan Broadcasting Corporation on April 10, 1986) is a side view showing an example of a conventional cathode ray tube display device, in which ■ is a CRT, and 2 is a narrow diameter portion 1a of a CRTI.
(near the electron gun) a substantially cylindrical annular core (toroidal core); 3.4 is a horizontal coil disposed substantially horizontally facing each other along the inner peripheral surface of the annular core 2; A vertical coil 6 is wound around the annular core 2 and generates a magnetic flux in a direction perpendicular to the magnetic flux of the horizontal coil 3.4.The horizontal coils 3, 4 and the vertical coil 5.6 form a deflection yoke 7. Configure. 8 is a magnetic shielding member provided along the expanded surface of the funnel portion 1b of the CRTI. In addition, in Fig. 5, the vertical coil 5.6 driven at a frequency around 6011□ is in the magnetic flux region (Magnet
ic field noise) is regulated by 10
KH2, and the level of its harmonics does not reach the limit, so they will be omitted to simplify the explanation.

Next, the operation will be explained.

In principle, the horizontal coils 3, 4 generate a horizontal magnetic flux, and the vertical coils 5.6 generate a vertical magnetic flux. For this reason, these two
A magnetic field with directional magnetic flux is formed at the center of the annular core 2. In addition, the horizontal magnetic flux and vertical magnetic flux mentioned above are the horizontal coil 3,
The strength of the magnetic field changes depending on the amount of current flowing through the vertical coils 4 and 5.6. This magnetic field deflects the electron beam passing through the narrow diameter portion la of the CRTI that has passed through the central portion of the annular core 2, thereby forming an image on the CRTI. That is, in FIG. 5, the deflection yoke 7
When currents as shown by symbols 9 and 10 flow through the horizontal coils 3.4, a horizontal magnetic flux 11 as shown by the solid arrow is generated and deflected as shown by the symbol 11.

By the way, magnetic fluxes of 12, 13° and 14.15 degrees are generated at the locations where the current directions shown by the symbols 9 and 10 at the front ends 3a, 4a and rear ends 3b, 4b of the horizontal coil 3.4 change, respectively, and these magnetic fields are generated. This mechanism generates unnecessary radiated magnetic flux 16,17 that does not particularly contribute to the deflection of the electron beam. The level of this unnecessary radiated magnetic flux 16.17 is due to the large opening on the front side of the deflection yoke 7, and (because the line length of the magnetic flux 12°13 is longer than that of the magnetic flux 14.15), the unnecessary radiated magnetic flux 17 becomes large. Figure 6 shows the magnetic flux when a display monitor or television equipped with this conventional deflection yoke device is measured using the measurement method of the West German unnecessary radiation control standard DEO877.The front magnetic flux of the deflection yoke 7 is 18°19.20 is a loop on the ground because the magnetic permeability of the ground is greater than that of air.In addition, in Fig. 6, DM is a display monitor, and EMI is a loop antenna for measuring unnecessary radiation.

[Problem that the invention seeks to solve]

Since the conventional cathode ray tube display device is constructed as described above, in order to prevent the influence of the unnecessary radiation magnetic flux 16 generated from the deflection yoke 7, it is made of a material with high magnetic permeability such as an iron plate or permalloy. The magnetic path must be made into a short loop, and the CRTl and deflection yoke 7, including the electronic circuits, are surrounded by iron plates, which reduces the service life and increases weight due to the temperature rise of the internal electronic circuits, resulting in deterioration of service. There was a problem with inviting people.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a cathode ray tube display device that does not cause a decrease in life or an increase in weight due to a rise in temperature of internal electronic circuits.

[Means for solving problems]

A cathode ray tube display device according to the present invention includes: a cathode ray tube in which a magnetic shielding member is provided on the expanded surface of the funnel portion; a substantially cylindrical annular core attached to a narrow diameter portion of the cathode ray tube;
A horizontal coil provided along the inner peripheral surface of the annular core, a vertical coil wound around the annular core, and a canceling coil wound along the circumferential direction of the magnetic shielding member. .

[Effect]

The cathode ray tube display device according to the present invention has a horizontal deflection current or its harmonic current flowing through a canceling coil wound along the circumferential direction of a magnetic shielding member provided along an expanded surface of a funnel portion. It is designed to cancel or reduce the magnetic field generated from the front side.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a sectional view showing one embodiment of the present invention, and the same or equivalent parts in FIG. 1 as in FIG. 4 are given the same reference numerals, and redundant explanation will be omitted.

In FIG. 1, reference numerals 21 and 22 denote cancel coils wound along the circumferential direction of the magnetic shielding member 8 provided along the outside of the expanded surface of the funnel portion tb, and this cancel coil 2L22 is attached to the deflection yoke 7. Upper horizontal coil 3
This is for bending unnecessary radiant magnetic flux 16 generated from the front side.

In addition, the horizontal coil 3,
4 or its harmonic current, where the harmonic frequency is n times (n is about 1 to 5).

The following operation will be explained.

In FIG. 2, when a current as indicated by reference numeral 9.10 is passed through the horizontal coil 3.4 of the deflection yoke 7, a horizontal magnetic flux H as indicated by the solid arrow is generated. Furthermore, when a horizontal deflection current or its harmonic current is passed through the canceling coils 21 and 22, magnetic fluxes 23 and 24 are generated. Therefore, each magnetic flux 25.26 generated at the front end 3a, 4a of the horizontal coil 3.4 at the location where the current direction indicated by reference numeral 9.10 changes.
is influenced by the magnetic fluxes 23 and 24 of the canceling coils 21 and 22, and the magnetic flux 25 is demagnetized and the magnetic flux 26 is magnetized, so these magnetic field generation mechanisms create an unnecessary width that does not particularly contribute to the deflection of the electron beam. The magnetic flux 17 is curved as shown in FIG.

Therefore, the canceling coil 2 is attached to the magnetic shielding member 8.
Figure 3 shows the magnetic field when measuring a cathode ray tube display device such as a display monitor DM or television equipped with 1.22 using the measurement method of the West German unnecessary radiation control standard VDEO877. Magnetic flux 18, 19.
20 is strongly curved toward the ground and is no longer detected by the loop antenna EMI for measuring unnecessary radiation. In addition, the deflection yoke 7
Although the magnetic flux on the rear side curves toward the air, it is originally a small magnetic flux and does not become a source of interference.

In the above embodiment, the horizontal deflection current is passed through the canceling coils 21 and 22, but the horizontal deflection current n
When a harmonic current with twice the frequency is passed, it is possible to strongly cancel n times as many unnecessary radiation components.

〔Effect of the invention〕

As described above, according to the present invention, the cathode ray tube display device is constructed by winding the canceling coil along the circumferential direction of the magnetic shielding member provided along the expanded surface of the funnel portion. The unnecessary radiation magnetic flux can be curved toward the ground side, and unnecessary radiation measures can be taken without using any special magnetic shielding materials.It is an inexpensive product that does not reduce the lifespan or increase the weight due to the temperature rise of the internal electronic circuit. This has the effect of providing a suitable device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a cathode ray tube display device according to an embodiment of the present invention, FIG. 2 is a conceptual diagram of the cathode ray tube display device for explaining the operations of FIGS. A side view showing the magnetic flux distribution when unnecessary radiated magnetic flux is measured using a cathode ray tube display device, FIG. 4 is a partially cutaway side view showing an example of a conventional cathode ray tube display device, and FIG. FIG. 6 is a conceptual diagram of a cathode ray tube display device for explaining the operation. FIG. 6 is a side view showing the magnetic flux distribution when unnecessary radiation magnetic flux is measured using a conventional cathode ray tube display device. ■ is a cathode ray tube (CRT), 1 b is a funnel part, 2
is an annular core, 3 and 4 are horizontal coils, 5 and 6 are vertical coils, 8 is a magnetic shielding member, and 21 and 22 are canceling coils. Note that the same reference numerals in the figures indicate the same or corresponding parts. (2 others) 2nd reason Figure 3 4th Sky 5.6: Einako Koi 1 and 52nd 6th floor

Claims (1)

[Claims] A cathode ray tube having a magnetic shielding member along the expanded surface of the funnel portion, a substantially cylindrical annular core attached to the narrow diameter portion of the cathode ray tube, and a horizontal coil provided along the inner peripheral surface of the annular core. and a vertical coil wound around the annular core, wherein a canceling coil is wound along a circumferential direction of a magnetic shielding member provided along an expanded surface of the funnel portion. A cathode ray tube display device characterized by: