JP2002084079A - Earth drawing structure of electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem where, with a molded housing case for a printed board of an electronic device, an earth is required to be drawn from a terminal stage for grounding an earth terminal pattern of a printed board. SOLUTION: Related to a mold case 2, an insert nut 4 comprising a conductive member where both ends are threaded is embedded in a printed board fixing stem. Related to the insert nut 4, a noise eliminating earth terminal pattern of a printed board 1 is screwed to one end while an earth wire 5 is screwed to the other end, for drawing out an earth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device for mounting electronic circuit elements on a printed circuit board, and using a case for storing the printed circuit board as a non-conductive molded product to protect and control various electric devices. More particularly, the present invention relates to a structure for extracting ground from a pattern electrode for noise of a printed board.

[0002]

2. Description of the Related Art As an electronic device of this type, for example, a single protection relay for mounting a digital circuit element on a printed board and generating a power cutoff signal (trip signal) by detecting a short circuit of a power device or the like to protect the device. There is. Other electronic devices include microcomputer-equipped electronic devices provided in household appliances such as washing machines, and single controllers for various machines such as lathe factories.

In a case where a storage case for a printed board on which an electronic circuit element is mounted is made of a metal housing as a structure for taking out the ground of such an electronic device, as shown in FIG. Therefore, by fixing the ground pattern portion of the printed board 1 to the housing 2, the ground can be taken out through the housing.

However, in the case of a molded product housing,
Since there is no conductivity, as shown in FIG. 2B, a ground wire is connected to a circuit connection terminal block 3 directly attached to the printed circuit board 1 to obtain grounding.

[0005]

In an electronic device employing a molded product housing, a terminal area of a printed board is used as a terminal for extracting ground, so that an area of a pattern for mounting electronic circuit components such as an IC is required. May be reduced to take out the ground, or the area of the printed board itself may be increased.

Further, since some terminals of the terminal block are used as ground terminals, the number of terminals taken out of the electronic circuit may be limited.

[0007] Also, in the wiring for extracting the ground from the terminal block, the ground wiring and the signal wiring of the circuit are close to each other, and noise is induced in the signal line of the electronic circuit, which may cause malfunction of a relay or the like. .

An object of the present invention is to provide an electronic device which solves all of the above-mentioned problems when a housing of a printed board is formed as a molded product and its ground extraction structure is adopted.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention embeds an insert nut made of a conductive member in a printed board fixing portion of a housing, and inserts the printed board through the insert nut. A connection between a grounding pattern portion and a ground wire is obtained, and is characterized by the following configuration.

An earthing structure of an electronic device in which an electronic circuit element is mounted on a printed board, and a storage case of the printed board is a non-conductive molded product, which is formed of a conductive member having both ends threaded, It has an insert nut embedded in a printed board fixing portion of the housing, one end of the insert nut is fixed to a ground extraction pattern portion for noise suppression of the printed board by screwing, and the other end is grounded of the printed board. It is characterized by a structure in which a ground wire for grounding the application pattern portion is screwed.

[0011]

FIG. 1 is a side sectional view of a ground extraction structure according to an embodiment of the present invention. The housing 2 is made of a molded product as in the related art, but an insert nut 4 made of a conductive member having both ends threaded can be embedded in a printed board fixing portion (stem in the drawing).

The insert nut 4 is embedded in the housing 2 and fixed to one end of the printed board 1 by a screw at a ground extraction pattern portion for noise suppression, and the other end is screwed to the ground wire 5 at the other end. You.

According to such a structure, even if the housing 2 is a molded product and is not conductive, the printed board 1 is screwed to one end of the insert nut 4 at the fixing portion.
The ground can be obtained from the other end of the insert nut 4 by the ground wire 5.

It is not necessary to use the terminal board of the printed board as a terminal for taking out the ground, and the area of the pattern for mounting electronic circuit components such as ICs on the printed board is reduced for taking out the ground. This eliminates the need to increase the area of the printed board itself. Further, some terminals of the terminal block are not used as ground terminals, and the number of terminals taken out from the electronic circuit is not restricted.

Further, the wiring for taking out from the terminal block eliminates the need for a grounding wiring, and can prevent noise from being induced from the grounding wire to the signal wiring of the electronic circuit.

The assembling work of the structure according to the present embodiment is the same as the usual work of fixing a printed board to a housing, and the number of working steps does not increase.

[0017]

As described above, according to the present invention, an insert nut made of a conductive member is buried in the printed board fixing portion of the housing, and the ground pattern portion of the printed board and the ground are inserted through the insert nut. Since the connection with the wire is obtained, the following effects are obtained.

(1) The area of a pattern for mounting an electronic circuit component such as an IC on a printed board is not reduced due to ground extraction.

(2) The area of the printed board itself is not increased.

(3) The number of terminals taken out from the electronic circuit is not restricted.

(4) It is possible to prevent noise from being induced from the ground line in the signal wiring of the electronic circuit.

(5) The assembling work is the same as the usual work of fixing the printed board to the housing, and the number of working steps does not increase.

[Brief description of the drawings]

FIG. 1 is a ground extraction structure showing an embodiment of the present invention.

FIG. 2 shows a conventional ground extraction structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Printed board 2 ... Housing 3 ... Terminal block 4 ... Insert nut 5 ... Earth wire

Claims (1)

[Claims] 1. A ground extraction structure for an electronic device in which an electronic circuit element is mounted on a printed board and a storage case of the printed board is a non-conductive molded product, and is formed of a conductive member having both ends threaded. And an insert nut embedded in a printed board fixing portion of the housing, one end of the insert nut being fixed to a ground lead pattern portion for noise suppression of the printed board by screwing, and the other end being a printed board. A grounding structure for an electronic device, wherein a grounding wire for grounding the grounding pattern portion is screwed.