JPS60230189A - 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 Technical Field of the Invention The present invention relates to a CRT display device, and more particularly to an improvement in the structure of the device for reducing radiation noise from the device.

Prior Art and Problems In recent years, CRT display devices have been widely used in computer terminal devices and personal computers, but radiation noise leaking from the devices to the outside has become a problem, and improvements are needed. . Particularly in a CRT display device, since the video signal is amplified, the frequency range of 30 to 100 MHz (7) is the largest radiation noise source. As a countermeasure to this, a coating such as conductive paint is applied to the inner surface of the plastic casing.
A common method is to connect to the ground on the circuit component side inside the housing. However, this level of countermeasures is still insufficient and often exceeds the standard, and further improvements are required.

(Q) Object of the Invention In view of the above-mentioned drawbacks of the conventional art, it is an object of the present invention to provide a CRT display device that effectively shields the source of radiation noise and reduces radiation noise.

(d) Structure of the Invention In order to achieve the above-mentioned object, the present invention uses a conductive film applied directly to the inner surface of the casing from the video signal amplification section in the neck of the CRT body, which is the largest source of radiation noise. It is characterized by being grounded.

+e+ Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram for explaining a method of grounding a CRT display device, which is an embodiment of the present invention. The inner surface of the device housing 1 is provided with a conductive coating 2 coated with, for example, nickel powder mixed with a binder, as in the conventional case. In CRT display devices, in order to improve the frequency characteristics of video signals, C
A video signal amplification printed circuit board 5 is placed close to a signal input section 4 of an electron gun inserted into the neck 3 of the RT main body.

The housing 1 can be divided into two parts, front and rear, and the CRT main body and drive circuit section are fixed to the resin molded body on the front side of the CRT device, and the back cover is attached after assembly and adjustment. A metal plate spring 7 is fixed to the ground pattern 6 of the printed circuit board 5 for video signal amplification, and when assembling the casing, the ground pattern 6 of the printed circuit board 5 for video signal amplification and the casing are connected via the plate spring 7. 1 is connected to the conductive coating 2 on the inner surface of the back cover. As a result of measuring radiation noise in the device of the present invention, an improvement of about 6 dB over the conventional grounding method was confirmed over the entire frequency range of 30 to 100 M11z, which is the most problematic radiation noise in CRT display devices.

FIG. 2 shows another embodiment of the invention. A metal plate is attached to the back side of the printed circuit board 5 for video signal amplification.

Shield plates 8 are arranged in parallel, and the metal shield plates 8 and the ground pattern 6 of the video signal amplification printed circuit board 5 are electrically connected. On the other hand, a metal plate spring 9 is fixed to the conductive coating 2 on the inner surface of the housing 1, and during assembly, the plate spring 9 and the metal shield plate 8 come into contact and are electrically connected.

The feature of this method is that in order to adjust the device, the plate spring 7 and the conductive coating 2 are removed by repeatedly attaching and detaching the back cover of the housing.
This is because it is possible to prevent the conductive film 2 from being easily peeled off due to rubbing and from becoming incompletely grounded. Furthermore, the metal shield plate 8 is effective in preventing leakage of radiation noise, further reducing radiation noise.

(f) Effects of the Invention As described in detail above, according to the present invention, by effectively shielding the largest source of radiation noise, a CRT display device with a simple structure, low cost, and low radiation noise can be achieved. Can be provided.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a grounding method of a CRT display device according to one embodiment of the present invention, and FIG. 2 is a diagram for explaining a grounding method of another embodiment.

Claims (3)

[Claims] (1) In a CRT display device that has a conductive coating on the inside of the casing in order to reduce unnecessary radiation noise leaking to the outside from the device casing, the grounding of the video signal amplification printed circuit board located on the neck of the CRT body C, characterized in that the pattern and the conductive coating on the inner surface of the casing are electrically connected.
RT display device. (2) In the above electrical connection, the connection is made to the conductive coating on the inner surface of the casing via a metal elastic body attached to a ground pattern of a printed circuit board for video signal amplification. The CRT display device described in . (3) In the above electrical connection, a metal plate or a metal case electrically connected to the earth pattern of the printed circuit board is installed on the side of the housing of the printed circuit board for video signal amplification, and a conductive coating is applied to the inner surface of the housing. 12. The CRT display device according to claim 11, wherein the CRT display device is connected to the metal plate or the metal case via a metal elastic body that is provided and electrically connected to the metal plate or the metal case.