JPS60253135A - Display device - Google Patents

Abstract

PURPOSE:To shield the external unnecessary magnetic field produced from a deflecting yoke with a simple means by covering almost all the CRT funnel portion and the deflecting yoke with non-magnetic and high conductivity metallic material. CONSTITUTION:Almost all the area of a funnel portion 1a of a CRT1 and whole of a deflecting yoke 2 are covered with a shield box 6 made of a non-magnetic and high conductivity metallic material such as aluminum. By this construction the external unnecessary magnetic field produced by the deflecting yoke 2 interlinks the shield box 6, in particular its high frequency horizontal component, produces eddy current in the shield box 6, and the magnetic field is cancelled, and thus the horizontal component of the external unnecessary magnetic field is prevented from leaking outside. The higher the frequency is, the more quantity of eddy current flow. The vertical component of the frequency of 50-60Hz is given little effect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a display device suitable for regulating electromagnetic interference in the 10 to 150 KHz band.

[Prior art]

In recent years, EM I (Electro magnetic
Interferenoe) <Movements to regulate interference in various countries are becoming more active. The frequency range for which interference waves are regulated has been expanded year by year, and for example, VDE
0871 classB vC d 10 KHz
Interference control in the ~30 MHz band (usually Fea)
0 MHz and above) has been established, and very strict limits are required. The above VDE regulations also apply to display monitors, but the deflection yokes used in cathode ray tube (hereinafter referred to as CRT) displays in current display devices emit a large amount of leakage magnetic field due to the nature of their functions. However, it has a fatal defect in that the surface leakage magnetic field of the horizontal deflection frequency and harmonic components 3 to 5 times higher than the horizontal deflection frequency completely exceeds the above-mentioned regulation value. In other words, the deflection yoke only needs to generate a deflection magnetic field inside the CRT in order to deflect the entire child beam of the CRT, but due to its structure,
The leakage magnetic field is also radiated in an unnecessary external direction.

FIG. 1 shows a complete diagram of a CRT (1) and a deflection yoke (2) commonly used in current CRT display devices (including general color and monochrome double-screens).

The deflection yoke (2) consists of horizontal and vertical deflection coils, each consisting of one bare coil. These windings are formed with saddle-shaped windings or toroidal windings, and are used in combination.This invention relates to a deflection yoke formed of saddle-shaped windings, which is the most commonly used horizontal deflection coil at present, and vertical The deflection coil is not covered by this invention and will therefore be omitted.

FIG. 2 shows a saddle-shaped horizontal deflection coil 1v (3). (4
) is a ferrite core that becomes the magnetic core. Normally, the vertical deflection coil p is wound with a toroid μ around this ferrite core (4). (3a) and (3b) are the front and rear bends, respectively, of the horizontal deflection coil /l/ (3).

FIG. 3 shows the model /L/l- of the □ horizontal deflection magnetic field (5) generated by the horizontal deflection coil /l/ (3). This figure is a side view of the CRT (υ) seen from the right side when facing the front.
This deflection magnetic field (5) deflects the electron beam in a direction that penetrates from the front to the back of the page. As is clear from the figure, it is sufficient to generate a deflection magnetic field only inside the CRT (υ), but due to the saddle winding configuration, it is particularly difficult to generate a deflection magnetic field at the bend part (3a
) or (3b), it can be seen that a large unnecessary leakage magnetic field to the outside is generated.

These bend portions (3a) and (3b) are unnecessary because they form a completely unnecessary magnetic field without generating the main magnetic field (the magnetic field for deflecting the original electron beam), but without them There is a contradiction in that coil formation is not possible.

The inventor has confirmed that the unnecessary magnetic field at the bend portion significantly contributes to electromagnetic field disturbance at the horizontal deflection frequency.

Also, this invention? It was confirmed that electromagnetic field interference can be significantly reduced by

[Summary of the invention]

Does this invention change the electromagnetic deflection system by removing unnecessary external magnetic fields generated from the deflection yoke? The purpose of this is to provide shielding using a simple means without causing any problems, and is characterized by covering almost the entire funnel portion and deflection yoke of the CRT with a non-magnetic and highly conductive metal material.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 4 shows an embodiment of the present invention. In this diagram,
(1B) is the funnel part of a CRT (υ), and almost the entire area of this funnel part (IS) and the entire deflection yoke (2) are made of a non-magnetic and highly conductive metal material such as aluminum. Covered by a shield box (6).

By covering in this way, the external unnecessary magnetic field generated from the deflection yoke (2) interlinks with the shield box (6), and especially the horizontal components with high frequencies are transmitted to the shield box (6).
6) As a result of transmitting K eddy radio waves, they are canceled and horizontal components are prevented from leaking to the outside in an external unnecessary magnetic field.

By the way, as is well known, eddy currents occur as a function of frequency! ! The higher the frequency, the better the current flows) 50~
It has little effect on the vertical frequency of 59 Hz. In other words, in order to cancel the horizontal magnetic field without affecting the vertical magnetic field VC in the external leakage magnetic field, the shield box (6) is made entirely of non-magnetic material and is made of a material with high conductivity. The reason for choosing a material with high conductivity is to efficiently flow eddy current and generate a canceling magnetic field.

In recent years, the technology of convergence has become mainstream in color display devices, and in this system, the perpendicular leakage magnetic field fcRT (1) is guided to the point gun, and compar sense is adjusted. Because of this, shielding methods that affect the vertical leakage magnetic field require a slight modification of the system design, which is fatal. In this sense, it is desirable to avoid using ferromagnetic materials in the shield box (6).

According to the inventor's study, there is no effect even if the shield box (6) covers only the deflection yoke (2).
It was confirmed that it was necessary to extend the metal to the front of OR'I' as much as possible, that is, it was necessary to cover almost the entire funnel part (1a).

By taking such measures, VDEo 8
71 The measurement method based on class BK measures the electromagnetic field interference strength in all directions of the display device by approximately I Q d
We were able to reduce the level of B or higher from no countermeasures.

Of course, these countermeasures have no effect whatsoever on electrical performance such as rasp distortion and convergence displayed on the CRT (1).

In this embodiment, the shield box (6) is made of aluminum as an example, but any non-magnetic material such as copper with good conductivity can be used.

〔Effect of the invention〕

As can be seen from the above explanation, according to this invention, U)?
Almost the entire funnel part and deflection yoke of the T are covered with gold, a non-magnetic and highly conductive metal material, which eliminates unnecessary external magnetic fields generated from deflection twisting, and eliminates the need for design changes to the WLat deflection system. It can be shielded by means.

[Brief explanation of the drawing]

Figure 1 is a side view of a display device used in a display device, Figure 2 is a perspective view of a deflection yoke (horizontal coil only),
FIG. 3 is a diagram of lines of magnetic force generated by a horizontal deflection coil, and FIG. 4 is a side view of a display device equipped with a shield box according to an embodiment of the present invention. (1)...Cathode ray tube, (2)...Deflection coil/l/i
3)...Horizontal deflection coil, (6)...Shield box. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa '11''l □29 Figure 3 Procedural amendment (voluntary) Ill 5 &"□'38 1. Indication of the case Japanese Patent Application No. 1987-109859 2. Title of invention display device 3. Person making the amendment Part 4 to Representative Hitoshi Katayama, ((Insertion 5) The columns of [Characteristics 11 Requested Range], [Detailed Explanation of Light 1], and ``Brief Explanation of Drawings'' of the specification to which the supplement is applied; Drawings. Contents of 6. Supplement 1-A, Specification: (1) Particulars; 1 Claims are appended to Supplement II as shown in the attached sheet. (2) Page 2, line 5, 1-1゜ ``3~ 5 times” should be changed to “2-5-8” Ill +E
Lmat. (3) Page 4, No. 9 Q'j tl ; Add "and display equipment cabinet" after "system". (4) 41st to 13th line 1-”. Add ``in a shape roughly following its external shape'' to the prefix ``with a stone''. (5) 4th j" * 13th line 11: r, L Next to T6°J [Alternatively, a cabinet for a display device] Is it possible to consider forming the unit itself from a metal material such as aluminum?1 1. The concave structure has major limitations (in addition, it is unavoidable to increase costs significantly, so it is unrealistic.) (6) 5th grade, line 6, 11゜ ``Thin radio waves'' It says "Eddy current" and i++1 island. (7) Page 6, No. 11, 11゜ "Confirmed. Next to J [Example of the installation shape of shield botsugesu (6) is shown in No. 5. The shield box (6) can be connected to the anode sleeve of C, RT (1) (not shown) or the deflection yoke (2).
) lead wire (1 not shown) to the chassis 1 (plate (14)
It is necessary to intervene between the yoke (2) and the purity convergence adjustment of the deflection yoke (2) is required!
It is desirable to use a separation type (to avoid the constraints of production l). In the embodiment of FIG. 5, the shield box (6) is
It is separated into an RT funnel part cover (6a) and deflection yoke part covers (6bt) and (8b,). In addition, when using a separate type, each joint should have an overlapping part as small as possible as shown by the diagonal line in the figure, and should be connected with a sufficiently low impedance in terms of hypochondrium, or magnetic shielding should be avoided. It is. ” will be added. (8) Page 6, line 18, 11゜ "Kira" is corrected to "Hatonto" +E L. (9) Page 7, line 5 IJ. Next to "Metal material (1)", add "In a shape that roughly follows its external shape". (10) Page 7, line 7, 11゜[Installation, 51 changes], ``and cabinet Y''
1 existing, 11” will be added. (item) Page 7, line 15; Add ``Figure 5 shows an example of the branch-like shape of the shield box'' in place of ``F perspective view.'' B, lfl +r+i (+) Submit Figure 5 as attached. Attachment hli If Features J4 Claims r(+) Almost the entire area of the funnel part and deflection yoke of the cathode ray In is made of non-magnetic material and highly conductive metal material; 1
A display family characterized by a shape that roughly follows the outline of 1 - covered: 6° treatment and 1 ridge 2 [Heten - 3 x △h" - Placement" Figure 5

Claims (1)

[Claims] (1) A display device characterized in that almost the entire funnel portion and deflection yoke of the cathode ray tube are covered with a non-magnetic and highly conductive metal material.