JPS6142684A - Crt display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a CRT display device, and more particularly to a structural improvement of the device for reducing radiation noise from the device.

[Conventional technology]

Recently, CRT display devices have been widely used as terminal devices of electronic computers or display units of personal computers, but radiation noise leaking from these CRT display devices to the outside has become a problem, and there is an urgent need to improve this problem. There is. In particular, a video signal is output from the main body of a personal computer, this video signal is amplified by a video signal amplification circuit connected to the neck of the CRT, and then input to the CRT. Radiation noise that leaks to the outside of the housing and propagates through the air is generated from a main printed circuit board that incorporates a CRT power supply circuit, etc., other than the board, and this radiation noise that leaks outside the housing can cause damage to the personal computer. There are problems such as causing malfunction of the kneeling body. Especially when the frequency is 30 to 100
The radiation noise level in the MHz region is large, and it is desired to suppress this radiation noise.

Conventionally, in order to suppress such radiation noise, a coating film of conductive paint was applied to the inside of the housing in which the CRT is installed, and a ground connection between this coating film and the main printed circuit board in which the power supply circuit of the CRT was installed was applied. This method was used to prevent radiation noise from leaking outside the plastic housing.

[Problem that the invention seeks to solve]

However, the structure of the conventional CRT display device described above has the problem that it is still insufficient to suppress the radiation noise within a specified range.

In addition, the temperature inside the casing in which the CRT is installed is Celsius.
Since the heat rises during RT operation, a slit-like hole is generally opened at the bottom of the housing to dissipate the heat to the outside through this slit-like hole, but this hole acts like a slot antenna. This causes problems such as emission of radiated noise to the outside.

[Means for solving problems]

The above problem can be solved by disposing a conductive member having a plurality of through holes at a predetermined distance from the printed circuit board, facing the ground pattern of the printed circuit board connected to the CRT main body installed in the housing; This problem is solved by the CRT display device of the present invention in which the conductive member and the ground pattern are electrically connected.

[Effect]

That is, a sheet-like conductive member with a plurality of through holes is placed opposite the ground pattern of a printed circuit board incorporating a CRT power supply circuit, etc., and this conductive member and the ground pattern of the printed circuit board are connected. By electrically connecting, the heat generated inside the CRT device is dissipated to the outside through the through hole of this conductive member, and at the same time, the radiation noise leaking to the outside is removed by this conductive member. This is what I did.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail using the drawings.

FIG. 1 is a conceptual diagram showing a first embodiment of the CRT display device of the present invention, FIG. 2 is an enlarged perspective view of the main part of the first embodiment of the CRT display device of the present invention, and FIG. invented CRT
FIG. 4 is a perspective view showing a second embodiment of the display device, and FIG. 4 is a perspective view showing a third embodiment of the CRT display device of the present invention.

As shown in FIGS. 1 and 2, the CRT display device of the present invention faces the ground pattern on the back side of the main printed circuit board 3 that constitutes the power circuit of the CRT 2 installed in the housing 1. A conductive member 5 made of a sheet-like copper plate or the like having a large number of through holes 4 is placed at a predetermined distance from the printed circuit board, and a shield plate 6 made of copper or the like is placed.
The point is that it is arranged in such a way that it is supported by.

This sheet-like conductive member 5 is electrically connected to the ground pattern of the printed circuit board 3, so that the ground potential of the printed circuit board 3 and the conductive member 5 are at the same potential.

Further, in this embodiment, the thickness of the sheet-like conductive member is 0.66 m or more, the diameter of the through hole 4 is 1.14 m or less,
The distance between the centers of the many through-holes 4 is 1.7 mm, or the number of holes per unit area of the sheet-like conductive member 5 is 233/645 m2. When an accident occurs where used parts burn out, the fall of combustible materials is avoided, which improves safety, and also prevents accidents such as electronic parts falling from the through hole and causing short circuits. It has also been found that a satisfactory value can be obtained for the mechanical strength of the sheet-like conductive member.

Furthermore, by doing this, the radiation noise generated mainly from the ground pattern side of the printed circuit board 3 is shielded by the sheet-like conductive member 5, and the measurement results show that the radiation noise level is reduced over a range of 4 db to 8 db. did.

Further, a second embodiment of the CRT display device of the present invention is shown in FIG. As shown in the figure, the second embodiment differs from the first embodiment in that the sheet-shaped conductive member 5 is placed opposite the ground pattern of the printed circuit board 5 that constitutes the power supply circuit of the CRT, etc. It is supported by a metal support 7 made of a conductive material such as copper. The number of these metal supports is four in i, but this number is not limited to four, and the metal supports 7 are electrically connected to the ground pattern of the printed circuit board 5 and have an equal potential. ing.

Furthermore, a third embodiment of the CRT display device of the present invention is shown in FIG. As shown in the figure, in this embodiment, a rectangular parallelepiped box-shaped shielding member 8 made of copper or the like, which is open at the top and has the through hole 4 described above at the bottom, is used, and this shielding member 8 is attached to the printed board 3. The pleated substrate 3 and a suitable support (not shown) are used to oppose each other. This shielding member 8 and the ground pattern of the printed circuit board 3 are connected so as to have equal potential.

Furthermore, the materials for forming the metal support 7, the conductive sheet 5, the shield plate 6, or the box-shaped shielding member 8 described in each of the above embodiments are not limited to copper, but may also include aluminum (All), nickel (N1''), Any material with good electrical conductivity, such as iron (Fe), may be used.

〔Effect of the invention〕

As described above, according to the CRT display device of the present invention, C
Radiated noise generated from the main printed circuit board that constitutes the RT power supply circuit, etc. is shielded by a conductive shield plate that is installed opposite to the ground pattern of the printed circuit board and has a through hole, so that radiation noise inside the CRT display device is shielded. In addition to dissipating the heat generated inside the device to the outside, it also prevents noise from leaking from the CRT display device to the outside.If such a CRT display device is used in the display section of electronic equipment such as a personal computer, Since the personal computer main body operates without any inconvenience such as malfunction, a highly reliable electronic device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing a first embodiment of a CRT display device of the present invention, FIG. 2 is an enlarged perspective view of essential parts of the first embodiment of a CRT display device of the present invention, and FIG. 3 is a conceptual diagram showing a first embodiment of a CRT display device of the present invention. FIG. 4 is a perspective view showing a third embodiment of the CRT display device of the present invention. In the figure, 1 is a housing, 2 is a CRT, 3 is a printed circuit board, 4 is a through hole, 5 is a sheet-like conductive member, 6 is a shield plate, 7 is a metal support, and 8 is a box-shaped shielding member. Figure 1 Figure 2

Claims (3)

[Claims] (1) A conductive member having a plurality of through holes is arranged opposite to the ground pattern of a printed circuit board connected to a CRT main body installed in a housing and separated from the printed circuit board at a predetermined interval, and A CRT display device characterized in that a magnetic member and a ground pattern are electrically connected. (2) The CRT display device according to claim (1), wherein the conductive member is in the form of a sheet. (3) The CRT display device according to claim (1), wherein the side of the conductive member facing the ground pattern of the printed circuit board has an open box shape.