JPH021910Y2 - - Google Patents

Description

[Detailed description of the invention] Technical field of the invention This invention relates to the casing structure of an electrical device, and includes a conductive layer (hereinafter referred to as a "shield layer") for electrical and magnetic shielding on the surface of the main body molded from synthetic resin.
That's what it means. ) by spraying zinc or applying conductive paint.

BACKGROUND OF THE INVENTION Certain electrical devices generate noise radio waves when they operate, and malfunction due to noise radio waves from the outside. In order to avoid disturbances caused by these radio noise waves, a method of shielding the electrical equipment by surrounding it with a grounded conductor is adopted.

If the casing of an electrical device is made of metal, the casing itself serves as a shielding layer, but if the casing is made of synthetic resin, the main surface of the casing may be sprayed with zinc or coated with conductive paint. A conductive layer is formed by depositing the conductive layer, which is grounded and used as a shield layer. This shield layer has the function of shielding noise radio waves, and also has the function of grounding these electric units by connecting the ground terminals of the electric units within the housing to this shield layer. Normally, grounding a conductive layer or conductive member provided on a frame or housing is called frame ground, and hereinafter abbreviated as FG.

By the way, a ground current flows through this FG shield layer from the electrical unit connected to it.
In addition, when an operator touches a conductive member connected to this shield layer, if the operator is charged with static electricity, the static electricity will be discharged (grounded) through the FG shield layer, and at this time, the FG Current flows through the shield layer. These currents naturally generate noise radio waves, but the FG shield layer is powerless against these noise radio waves, so it should not be used for electrical units that are particularly sensitive to noise radio waves.
It is further surrounded by a conductive layer insulated from the FG shield layer for shielding, and this is called a signal ground (hereinafter abbreviated as "SG"). The SG shield layer is normally connected to and grounded to the FG shield layer near the grounding position of the FG shield layer.

Prior Art and Problems Figure 1 shows an example of a conventional housing structure in which an FG shield layer and an SG shield layer are provided. In the figure, 1
2 is an upper casing, and 2 is a lower casing, which are made of synthetic resin molded products. 3 is a partition plate, and this partition plate 3 is made of a metal plate, and electrical units A and B shown by imaginary lines are connected to each other.
is installed on this partition plate 3, and its ground terminal is connected to this partition plate 3. 4 and 5 are shield layers for FG formed on the inner surfaces of the casings 1 and 2 by spraying zinc or applying conductive paint,
These shield layers 4, 5 and partition plate 3 are connected to each other at their fitting portions 6. C shown by an imaginary line is an electric unit that is particularly sensitive to noise, and an SG shield layer 7 is provided surrounding this electric unit C. The SG shield layer 7 is a casing made of an aluminum plate, and is attached to the casing 2 via an insulator 8. It is connected to the shield layer 5.

Conventionally, the FG shield layers 4 and 5 are formed on the surfaces of the resin casings 1 and 2, and when the SG shield layer 7 is required, this is formed from an aluminum plate. However, in such a conventional structure, the processing of the aluminum plate that becomes the SG shield layer 7 and the insulator 8
This processing is required separately from the processing of the casings 1 and 2 and the partition plate 3, and the number of man-hours required for assembling them is also high, causing an increase in the cost of the casing.

Purpose of the invention The present invention solves the above-mentioned problems and provides a housing structure in which the FG shield layer and the SG shield layer can be formed at low cost, thereby making it possible to provide electrical devices at a lower cost. It was done with the purpose of

Structure of the invention The casing structure of this invention is such that when forming a conductive layer on a resin casing by spraying zinc or applying conductive paint, for example, masking tape is pasted on the surface of the resin main body in advance to form a conductive layer. By subsequently peeling off this masking tape, the conductive layer is divided into two layers that are not connected to each other, and the other conductive layer is contained within the space surrounded by one of the divided conductive layers. FG one side
It is characterized in that the other is used as a shield layer for SG, and the other is used as a shield layer for SG.

Embodiment of the invention Figure 2 shows the first embodiment of the invention.
A structure corresponding to the conventional structure of FIG. 1 is shown.

In FIG. 2, reference numeral 11 indicates a standing wall provided to surround the electric unit C from the lower casing 2, and 12 indicates a partition plate made of synthetic resin fitted to the upper end of the standing wall 11.
1. The partition plate 12 and the bottom plate 13 of the lower housing 2 form an internal housing 14 that surrounds the electric unit C. On the outer wall surface of the standing wall 11, there is a
A conductive layer 15 is formed integrally with the FG shield layer 5, and a conductive layer 16 that is separated from the conductive layer 15 on the outer wall surface at the top 11a of the vertical wall 11 is formed on the inner wall surface of the vertical wall 11 and the upper surface of the bottom plate 13. formed,
Further, a conductive layer 17 is formed on the lower surface of the bottom plate 13 and is connected to the FG shield layer 5 of the lower housing 2. These conductive layers 15, 16, 17 form the vertical wall 11
The conductive layer is formed by spraying zinc or applying conductive paint to the main resin molded product with masking applied to the top part 11a of the mask, and then peeling off the masking tape to form a conductive layer. 15 and 16 are separated. On the other hand, partition plate 1
Conductive layers 18 and 19 separated by the fitting part 11a with the standing wall 11 are formed on the upper and lower surfaces of the resin main body 2, and when these are fitted to the standing wall 11, the conductive layers 15 and 18 and 16 and 19 are in contact with each other so that they are electrically connected. Reference numeral 20 denotes a through hole provided in the lower housing 2 so that the conductive layers 15 and 17 can be formed continuously.

According to the above configuration, the internal casing 14 surrounding the electric unit C includes conductive layers 15, 17 and 1.
8 and conductive layers 16 and 1.
9 is formed, and the outer conductive layer is formed integrally with the FG shield layer 5 of the lower casing.
9 can be used as a shield layer for SG,
The electric unit C can be protected from noise radio waves generated by the current flowing through the FG shield layer 5.

In the case shown in Figures 1 and 2, the electric unit C is completely surrounded by a shield layer for FG and a shield layer for SG, but the source of the noise radio waves is isolated. In the past, if you wanted to protect a specific electrical unit from this noise radio waves, you would actually want to protect a part of the area around the electrical unit you are trying to protect.
In many cases, it is sufficient to form a shield layer for SG. In order to illustrate such an example, FIGS. 3 to 5 show a second embodiment in which the present invention is implemented in the case of a display device with a floppy disk unit. FIG. 4 is a cross-sectional view of the S section in FIG. 4, FIG. 4 is a perspective view of the partition plate, and FIG. 5 is a perspective view of the lower casing.

In the electrical units shown in phantom lines in Figures 4 and 5, D is a display cathode ray tube, E is a floppy disk unit, F is a power supply, G is a cooling air blower, and H is a circuit board. The power supply F becomes a source of noise radio waves, and the floppy disk unit E and the circuit board H become units to be protected from noise.

Therefore, in this case, the vertical wall 21 is installed to shield the side and rear surfaces of the floppy disk unit E.
is provided on the partition plate 22, and a vertical wall 23 is provided on the lower housing 2 to shield the circuit board H from the power source F.
is provided. Then, SG shield layers 24 and 25 are formed on the lower housing 2 and the partition plate 22 so as to surround the floppy disk unit E and the circuit board H, and the SG shield layers 24 and 25 are formed on other parts of the SG shield layer. Shield layers 26 and 27 are formed. 28 is the shield layer 24, 25 for SG and FG
This is a masking portion that separates the shield layers 26 and 27 from each other. Note that 29 is an FG shield layer provided on the inner surface of the upper housing 1, and these FG shield layers 26, 27, 29 and SG shield layers 24, 25 are separated when the housing is assembled. Similar to the first embodiment, the fitting portions contact each other and are electrically conductive.

Effects of the Invention According to the casing structure of the present invention as explained above, when forming a FG shield layer on a resin casing by zinc spraying or applying conductive paint, the FG shield can be applied to the necessary locations. The SG shield layer and the insulated SG shield layer can be formed at the same time, and there is no need to create an SG shield casing from an aluminum plate or the like and attach it via an insulator. The vertical walls for forming the SG shield layer can be appropriately molded as one piece by taking advantage of the properties of the synthetic resin material, making it possible to manufacture a housing with the FG and SG shield layers at an extremely low cost. This has the effect of reducing the cost of electrical equipment.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional housing structure, Figure 2 is a sectional view showing an embodiment of the housing structure of the present invention corresponding to Figure 1, and Figures 3 to 5 are sectional views of the housing structure of the present invention. 3 is a cross-sectional view of the S section of FIG. 4, FIG. 4 is a perspective view of the partition plate, and FIG. 5 is a perspective view of the lower casing. In the figure, 1 is the upper case, 2 is the lower case, 4, 5,
15, 17, 18, 26, 27, 29 are shield layers for FG, 16, 19, 24, 25 are shield layers for SG, 9 is a grounding position, 10 is a conductor, 11, 2
1 and 23 are standing walls, 12 and 22 are partition plates, 11a,
28 is a part where the conductive layer is divided, A to H are electrical units, and C, E, and H are electrical units that dislike noise.

Claims (1)

[Scope of utility model registration request] In a case having a structure in which a conductive layer is provided on the main surface of a resin case or partition wall (hereinafter simply referred to as "the case") for electrical and magnetic shielding for the electrical equipment surrounded by the case, A conductive layer is formed by dividing into two layers, and the other conductive layer is included in a space surrounded by one of the divided conductive layers, and one conductive layer is used for frame grounding, and the other conductive layer is used for frame grounding. A housing structure for an electrical device characterized by its use as a signal ground.