JPH0322499A - Electromagnetic shielding structure of card - Google Patents

Abstract

PURPOSE:To suppress electromagnetic noise of a card easily without changing an electromagnetic shield structure of the main body of an electronic apparatus, by a construction wherein the ground for signals of the card itself is isolated completely from the ground for electromagnetic shield. CONSTITUTION:A ground pin 26 for shield is connected to a ground pattern block 62B for electromagnetic shield by a connection 30C and connected electrically, at the point of a conductive connection element 62A, to a shield metal plate 64 on the upper side of a card via a first spring 62. The metal shield plate 64 on the upper side of the card has a conductive connection element 63A and it is connected, at the point of a conductive connection element 63B, to a metal shield plate 65 on the lower side of the card by a second spring 63. These routes for electric connection are insulated from a connection line of a signal-side ground pin 22, and thus a noise component contained in a signal- side ground line 30A is prevented from flowing into the metal shield plates 64 and 65 on the upper and lower sides.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an electromagnetic shielding structure for a card.

[Conventional technology and its issues]

Recently, card-based circuit boards mainly used for memory expansion have been provided on the market attached to electronic devices, so it is not a problem if the card itself is housed inside the electronic device. Electromagnetic radiation noise, which used to be ignored, has gradually become more important. In particular, when a card is installed and exposed outside of an electronic device, if the cords of peripheral devices are near the card, electromagnetic noise generated from the card will use these cords as antennas and radiate electromagnetic noise to the surrounding area. There are now situations in which the standards of the FCC and VCCI, which are institutions that have legal enforcement power, are not complied with regarding electromagnetic radiation regulation values.

FIG. 4 is a block diagram of a system using cards.

Reference numeral 1 denotes a system body into which the card 2 is inserted, such as a word processor, a personal computer, or the like. 6 is a connector for peripheral devices such as RS232C, 4 is a printer connector, 5 is a power supply connector, 6 is a liquid crystal display, 7 is a keyboard, 8 is a key, 9 is a printer cable, 10 is an input connector for the printer 11, 12 is a printer operation button , 14
is the printing section of the printer.

The card 2 protrudes outside the main body 1 of the system as shown in the figure, and when the printer cable 9 approaches the card 2 from the printer cable position 9A to the connection position 9B with the card, electromagnetic radiation is emitted from the card 2. When noise is generated, the printer cable 9 is electromagnetically coupled even if a shielded wire is used, and the electromagnetic noise is inductively generated and reaches a long distance using the printer cable 9 as an antenna. It will radiate electromagnetic noise. Since these noises sometimes exceed the above-mentioned FCC and VCCI standard values, measures such as shielding the printer cable 9 more completely or wrapping it in a ferrite core 15 are generally used. However, in many cases, these methods are expensive and are provided by a separate manufacturer from the system itself, making them very inconvenient and, if the card is exposed in the system, a complete solution. This was a big problem as it was not possible to take it.

[Means and actions to solve the problem]

The present invention takes a structure in which the signal ground and the electromagnetic shielding ground of the card itself are completely separated. This makes it possible to effectively reduce electromagnetic noise.

〔Example〕

The present invention will be explained below with reference to the drawings.

FIG. 1 is an explanatory diagram showing the internal structure of the card of the present invention.

20 is a connector, 20A shows the top surface of the connector having a plurality of arrays, and 20B shows the side surface of the connector. From the system body 1 in FIG. 4, the power supply,
The signal and ground lines are connected, and 22
is the signal side ground pin, 26, 25 are the signal pins, 2
4 is a power input pin, and 26 is a ground pin for shielding, each of which constitutes a connection pin of the connector. The connector 20 is attached to the end of the circuit board 6o, and connected to, for example, a memory IC 31 by means of a signal side ground line 60A1, a power line 30B, etc. configured with printed wiring.
~4o.

60C is an electromagnetic shield ground line connected to an electromagnetic shield pattern block 62B, which will be described later. 2
3 and 25 are signal pins, and their input connections are omitted, but the respective signal lines are connected to the respective memory ICs 31 to 4.
Connected to 0.

The connection of the power input pin 24 is such that after power is supplied to the memory ICs 31 to 4o by the power line 30B, it is connected to the backup battery 51 via the voltage detection circuit 50 by the connections 30D and 30H. Even if the card is removed from the system and the power supply from the system is stopped, the backup battery 51 will
Electric power is supplied to each memory IC 31-40 so that the memory contents are retained. The shielding ground bin 26 is connected to the electromagnetic shielding ground pattern block 62B by a wire connection 30C, and forms a ground line independent of the signal side ground pin 22. The gist of the present invention is to connect the line of the electromagnetic shielding ground pattern block 62B to the signal side ground pin 2.
2 and prevents noise signals contained in the signal side ground line from flowing to the metal shield plates on the upper and lower surfaces of the card, which will be described later.An example of the connection will be explained below with reference to FIG.

FIG. 2 is an internal wiring diagram of the card of the present invention.

As shown in FIG. 1, the shield ground pin 26
is connected to the electromagnetic shielding ground pattern block 62B by the connection 30C, and the first spring 62
It is electrically connected to the card top shield metal plate 64 at a conductive connection portion 62A via the conductive connection portion 62A. The card top metal shield plate 64 has a conductive connection part 63A, which is connected to the card bottom metal shield plate 65 at the conductive connection part (53B) by the second spring 63.

These electrical connection paths are connected to the signal side ground pin 22.
The structure is such that noise components contained in the signal side ground line 30A do not flow into the metal shield plates 64 and 65 on the upper and lower surfaces. The connection of the connector's connection pins 22, 26, 24, 25, memory ICs 31 to 40, and backup battery 51 has been explained using FIG. stay.

FIG. 3 is a cross-sectional view of the card of the present invention.

The electromagnetic shielding ground pattern block 62B provided on the circuit board 60 is
It is connected to the top shield metal plate 64 at a conductive connection portion 62A. The spring 62 is housed inside a through hole 71B provided in a support frame 71A made of an insulator such as plastic that supports the upper and lower metal shield plates 64 and 65 of the card. The other conductive connection portion 63A of the upper metal shield plate 64 is electrically connected to the lower metal shield plate 65 at a conductive connection portion 63B by the second spring 63. The second spring 66 is held inside the hole 71C of the support frame 71A.

75A and 75B are adhesive parts made of adhesive, for example, and connect the upper and lower metal shield plates 64 and 65 to the support frame 7.
1A, the card is integrated by adhering to the circuit board 60. 26 is the aforementioned ground bin for shielding, for example, which constitutes the female side connector pin,
Male side system body side connector bin 82, system body side connector 86, system body side circuit board 81,
It is connected to the electromagnetic shield ground on the system main body side by a system main body side electromagnetic shield ground connection point 85. Generally, the electromagnetic shielding ground on the side of the system main body is directly connected to the main power supply ground or a ground line with a large capacity by an independent ground line with low resistance. Therefore, the noise component generated in the ground line of the signal line from the power supply to the card is
It does not overlap the ground line for electromagnetic shielding, and therefore, electromagnetic noise is not emitted to the outside of the upper and lower shield metal plates of the card. Further, the structure of the present invention is strong against electrostatic shock from the outside and provides a very effective shielding means.

As mentioned above, the present invention relates to the electromagnetic shielding structure of a card, in which one of the plurality of connector pins connected to the circuit board is used as a signal ground line, and the other one is used as the original ground line. By connecting to the electromagnetic shielding ground line that is directly connected to the power ground, the noise components generated in the signal ground line will not be superimposed on the electromagnetic shielding ground line, and will be connected to the metal shield plate on the top and bottom surfaces of the card. This connection electromagnetically shields the noise component of the signal side ground line that also occurs on the circuit board inside the card.

In addition to the above-described embodiments, the electromagnetic shielding means of the present invention can also be used in combination with a conventional electromagnetic shielding board that coats almost the entire surface of a circuit board, and the same can be applied to other equipment and system combinations. It can be applied to

〔Effect of the invention〕

The present invention provides a means for suppressing electromagnetic noise emitted from cards, and by adopting this method,
The electromagnetic noise of the card can be easily suppressed without changing the electromagnetic shielding structure of the main body of the electronic device.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the internal structure of the card of the present invention, Figure 2 is an explanatory diagram showing the internal structure of the card of the invention.
The figure is a wiring diagram inside the card of the present invention, FIG. 3 is a sectional view of the card of the present invention, and FIG. 4 is a configuration diagram of a system using a power cord. 1...System body, 2...Card, 22...Signal side ground pin, 26...
・Shield ground pin, 60...Circuit board, 30A...Signal side ground line, 30B...
...Power line, 30C... Electromagnetic shield ground line, 62
...First spring, 66...Second spring, 64...Top metal shield plate, 65...
・Bottom direct metal shield plate, 71A...Support frame.

Claims (1)

[Claims] In a card having a plurality of connector pins connected to a circuit board, a metal shield plate that covers the circuit board surface on the upper and lower surfaces, and a support frame for keeping the two metal shield plates at a constant distance, the plurality of As part of the configuration of the connector pin, a signal side ground pin connected to the ground of the IC on the circuit board and a shield ground pin connected to both metal shield plates are provided independently, and the shield ground pin An electromagnetic shielding structure for a card, wherein the connection is electrically connected to both metal shield plates by a spring passing through a through hole of the support frame.