JP2000208013A - Proximity switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of component items and assembling man-hours, and realize cost reduction, by improving the assembly structure of a proximity switch. SOLUTION: A proximity switch made up by incorporating a coil part 1, comprising a detection coil 1a and a core 1b, and a printed circuit board 3 into a body case 6, has an assembly structure in which the coil part and the printed circuit board are housed in a coil cap 2 made of resin and a protection case 4, respectively, and these components are connected to each other by a joint member 5. The joint member 5 is made up of a resin molding equipped with an end projection part 5a to be fitted into a center hole in the core, a board-fixing groove part 5b for inserting an end part of the printed circuit board therein, a nail part 5c to be caught in an engagement hole 4a in the protection case, a nail part 5d-1 to be caught in an engagement hole 2a in the coil cap 2, and an arm part 5e for pressing the coil part from the back side against the coil cap at its installing position. and the protection case and joint member are made of conductive resin, thereby giving a function of electrostatic shielding to the protection case.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a proximity switch, and more particularly, to an assembly structure of a proximity switch.

[0002]

2. Description of the Related Art First, FIGS. 2A to 2C show an assembly structure of a conventional proximity switch. In the figure, reference numeral 1 denotes a coil portion in which a detection coil 1a and a core 1b are combined, 2 denotes a resin coil cap surrounding the coil portion 1, 3 denotes an electronic component (not shown) of a detection circuit, and a display element (LED). ) 3a
, A resin protective case housing the printed circuit board 3, a printed circuit board 3, a joint member serving as a resin molded product for supporting the protective case 4 on the core 1 b of the coil unit 1, and 6 a metal , A coil lead wire drawn from the detection coil 1a and connected to the printed circuit board 3, an external connector 8 attached to a rear case 6a of the main case 6, and an external lead wire 8a. The inside of the main body case 6 is filled with a casting resin between the protection case 4 and the protection case 4. The protection case 4 prevents the stress of the casting resin from being applied to the electronic components mounted on the printed circuit board 3. ing.

Here, the coil portion 1 and the coil cap 2 are fixed with an adhesive. The joint member 5 has a tip projection 5a inserted into a hole 1b-1 opened at the center of the core 1b, a board fixing groove 5b into which the tip of the printed board 3 is inserted in a press-fit manner, and a peripheral surface of the protection case 4. A pair of upper and lower protruding claw portions 5 that engage with the opened engagement holes 4a from the inner peripheral side.
c is formed, and the distal end protruding portion 5a is inserted into the hole 1b-1 of the core 1b and fixed to the coil portion 1 with an adhesive.

In order to shield the detection coil 1a of the coil section 1 and the circuit section of the printed circuit board 3 against external noise, the coil section 1 is connected to the ground of the printed circuit board 3 via a lead wire. For the circuit portion of the printed circuit board 3, the circuit portion is covered with a shielding material 9 such as copper foil, and the shielding material 9 is connected to the ground terminal provided on the printed circuit board 3. Like that.

In the assembling process of the proximity switch having such a configuration, the coil portion 1 and the coil cap 2 and the coil portion 1 and the joint member 5 are fixed with an adhesive, and then the printed circuit board 3 is attached to the joint member 5. The coil lead wire 7 and the ground lead wire drawn out of the coil portion 1 after being inserted and connected to the board fixing groove portion 5b are soldered to the terminals of the printed board 3. Further, the printed circuit board 3 is covered with the shield plate 9 and connected to the ground terminal, and further covered with the protective cap 4.
The protective cap 4 is engaged with the claw 5c of the joint member 5. After the assembly is assembled in the main body case 6, the interior of the main body case 6 is filled with a casting resin.

[0006]

However, the conventional assembling structure having the above structure has the following problems.

(1) Since the assembling with the coil portion 1, the coil cap 2, and the joint member 5 requires a bonding step,
As the number of assembling man-hours increases, the bonding work takes time,
This is what drives up the cost of the product.

(2) As a countermeasure against electrostatic noise against external noise, it is necessary to wind a copper foil around the printed circuit board 3 and to wire and solder an earth lead wire to the coil portion 1. Assembly man-hours increase.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a proximity switch having an improved assembly structure so that the number of parts and the number of assembly steps can be reduced in order to reduce costs. .

[0010]

According to the present invention, in order to achieve the above-mentioned object, a coil portion including a detection coil and a core, and a printed circuit board on which a detection circuit and a display element are mounted are incorporated in a main body case. A configured proximity switch,
The coil part and the printed circuit board are housed in a resin coil cap and a protective case, respectively, and the parts are interconnected via a joint member. The joint member is opened at the center of the core. Protruding part to be fitted in the hole formed, board fixing groove for inserting the end of the printed circuit board, claw part to be fitted from the inner peripheral side into the engaging hole opened in the peripheral surface of the protective case, and opening in the peripheral surface of the coil cap A resin molded product having a claw portion fitted into the engagement hole from the inner peripheral side, and an arm portion for pressing the coil portion from behind to the end face of the coil cap at the assembly position (claim 1). Specifically, it is configured in the following manner.

(1) A projection is provided on the arm of the joint member facing the core back surface of the coil, and the projection is pressed against the coil at the assembly position.

(2) The protective case and the joint member are formed of a conductive resin, and the joint member and the ground terminal of the printed circuit board are brought into electrical contact with each other at the assembling position, so that the circuit of the printed circuit board is electrostatically charged by the protective case. Shield (claim 3).

(3) A projection is formed in the board fixing groove of the joint member so as to contact the ground terminal of the printed board.

(4) A display window covered with a transparent resin is formed on a part of the peripheral surface of the protective case so as to face the detection display element mounted on the printed circuit board.

According to the above construction, no assembling work is required for assembling the components inside the switch, and the assembly can be efficiently performed only by simple fitting between the components.

In particular, an arm with a projection is provided on the joint member,
By using the bending elasticity to press the coil portion against the front end face of the coil cap, the variation in the thickness of the coil portion can be absorbed and the coil portion can be stably held at the assembly position.

Further, the protective case and the joint member are formed of a conductive resin, and the joint member and the ground terminal of the printed board are electrically contacted at the assembly position so that the circuit of the printed board is electrostatically shielded by the middle case. By doing so, the protective case can be provided with a shielding function, and the wiring of the lead wire connecting between the coil portion and the ground terminal of the printed circuit board becomes unnecessary.

[0018]

FIG. 1 is a block diagram showing an embodiment of the present invention.
A description will be given based on the examples shown in (a) to (e). In the drawings of the embodiment, the same members corresponding to FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted.

In this embodiment, the coil portion 1, the coil cap 2, the printed circuit board 3, and the protective case 4 are fitted to the assembly position via the joint member 5 as a resin molded product without using an adhesive. Are joined together.

That is, in addition to the tip protrusion 5a, the substrate fixing groove 5b, and the claw 5c that engages with the protective case 4 described with reference to FIG. A pair of upper and lower arms 5 protruding in an L-shape in the radial direction.
d, a projecting engagement claw 5d-1 formed on the outer peripheral end surface of the arm 5d, a pair of upper and lower arms 5e projecting radially toward the back surface of the core 1b of the coil 1, and A projection 5e-1 projecting from the tip of the arm toward the core 1b is integrally formed. An engaging hole 2a is formed in the peripheral surface of the coil cap 2 so as to face the claw 5d-1.

The protective case 4 and the joint member 5 are made of a conductive resin, and the protective case 4 is made of a transparent resin at a portion facing the display element (LED) 3a mounted on the printed circuit board 3. A formed display window 4b is formed. Further, for the joint member 5, the substrate fixing groove 5
At the position where the printed circuit board 3 is inserted and connected inside b, a projection 5b-1 is formed which contacts the ground terminal 3b formed on the substrate side.

In the above-described configuration, the tip projection 5a of the joint member 5 is inserted and connected to the center hole 1b-1 opened in the core 1b of the coil portion 1, and then the coil portion 1 is inserted into the coil cap 2. When the joint member 5 is pushed in so as to press the coil portion 1 against the front end surface of the coil cap 2, the engagement protrusion 5d-1 of the joint member 5 is caught by the engagement hole 2a opened in the peripheral surface of the coil cap 2, and The space is joined (Fig. 1
(d)). In this case, the protrusion 5e-1 formed on the arm 5e of the joint member 5 abuts against the back surface of the core 1b, and the elasticity of the flexible arm 5e presses the coil 1 against the end face of the coil cap 2. Variations in the thickness of the coil portion 1 can be absorbed, and the coil portion 1 can be stably held at the assembly position.

When the front end of the printed circuit board 3 is press-fitted into the board fixing groove 5b of the joint member 5 to connect the two, the projection 5b-1 of the board fixing groove 5b contacts the ground terminal 3b of the printed board 3 at the same time. The core 1b of the coil unit 1 and the ground terminal 3b of the printed circuit board 3 are electrically connected via the joint member 5 made of a conductive resin.

Further, the printed circuit board 3 is covered with the protective case 4 and pushed forward, and the engaging hole 4a opened on the peripheral surface on the tip side is hooked on the engaging projection 5d-1 of the joint member 5 to assemble. When fixed to the position, the conductive protective case 4 also serving as an electrostatic shield for the printed circuit board 3 is connected to the ground terminal 3 b of the printed circuit board 3 via the conductive joint member 5.
And the display window 4b of the protective case 4 faces the display element 3a mounted on the printed circuit board 3 at this assembly position.

This eliminates the need for laborious bonding work in the assembly process of the internal assembly.
, The protective case 4 serves as an electrostatic shield, so that the shield member 9 as described in FIG. 2 can be omitted.

The internal assembly assembled in this manner is incorporated in a metal main body case 6 and sealed with a resin, similarly to the conventional apparatus of FIG.

[0027]

As described above, according to the structure of the present invention, no assembly work is required for assembling parts inside the switch, and the switch can be efficiently assembled only by simple fitting between the parts.

In particular, an arm with a projection is provided on the joint member,
By using the bending elasticity to press the coil portion against the front end face of the coil cap, the variation in the thickness of the coil portion can be absorbed and the coil portion can be stably held at the assembly position.

Further, the protective case and the joint member are formed of a conductive resin, and the joint member and the ground terminal of the printed board are electrically contacted at the assembly position, so that the circuit of the printed board is electrostatically shielded by the middle case. This allows the protective case to have a shielding function and eliminates the need for lead wires connecting the coil section and the ground terminal on the printed circuit board. Points can be reduced and costs can be reduced.

[Brief description of the drawings]

1 is a configuration diagram of a proximity switch according to an embodiment of the present invention, (a) is a longitudinal side view, (b) is a cross-sectional plan view, (c) is a rear end view of a joint member, (d) is ( b) Enlarged view of main part in figure, (e) Plan view of protective case

FIG. 2 is a configuration diagram of a conventional proximity switch;
(a) is a longitudinal side view, (b) is a cross-sectional plan view, and (c) is a rear end view of the joint member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coil part 1a Detection coil 1b Core 2 Coil cap 2a Engagement hole 3 Printed circuit board 3a Display element (LED) 3b Ground terminal 4 Protective case 4a Engagement hole 4b Display window 5 Joint member 5a Tip protrusion 5b Board fixing groove 5c , 5d-1 Claw 5e Arm 5e-1 Projection 6 Body case 7 Coil lead wire

Claims (5)

[Claims] 1. A proximity switch in which a coil part comprising a detection coil and a core, and a printed circuit board on which a detection circuit and a display element are mounted are incorporated in a main body case, wherein the coil part and the printed circuit board are each made of resin. A coil cap, a protective case, wherein the components are interconnected via a joint member, wherein the joint member is fitted into a hole opened at the center of the core, and a printed tip is provided. A board fixing groove for inserting the end of the board, a claw portion which fits into the engaging hole opened on the peripheral surface of the protective case from the inner peripheral side, and a fitting hole which is opened on the peripheral surface of the coil cap from the inner peripheral side. A proximity switch comprising: a resin molded product having a claw portion to be pressed and an arm portion for pressing the coil portion from behind to an end face of the coil cap at an assembly position. 2. The proximity switch according to claim 1, wherein a projection is provided on the arm of the joint member facing the back surface of the core of the coil, and the projection is pressed against the coil at the assembly position. And proximity switch. 3. The proximity switch according to claim 1, wherein the protective case and the joint member are formed of a conductive resin, and the joint member and the ground terminal of the printed board are brought into electrical contact at the assembly position. A proximity switch characterized in that the above circuit is electrostatically shielded with a protective case. 4. The proximity switch according to claim 3, wherein a protrusion is formed in the board fixing groove of the joint member so as to be in contact with the ground terminal of the printed circuit board. 5. The proximity switch according to claim 1, wherein a display window covered with a transparent resin is formed on a part of a peripheral surface of the protective case so as to face the detection display element mounted on the printed circuit board. And proximity switch.