JPH11312445A - Electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure an insulation property of a circuit part, to prevent it from being affected by a use temperature cycle, and to improve assembly. SOLUTION: A box-shaped circuit case 11 molded from resin is prepared and an electronic circuit 12 and a coil 13 are mounted therein. A frame-like metallic casing 14 is molded by die-casting for covering outer circumferential side walls of the circuit case 11 and a cover 15. In order to shield a circuit part from the exterior, the cover 15 is mounted on an opening part of the circuit case 11 with the metallic casing 14 interposed therebetween. By injecting a filler resin 16 into an upper space in the circuit case 11 and curing it, the circuit case 11 and the cover 15 are sticked on each other. The circuit case 11 and the metallic casing 14 are thereby unified and a small-sized electronic apparatus is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device having a metal housing, and more particularly to an electronic device having an improved method of integrating a metal housing and a circuit section.

[0002]

2. Description of the Related Art As an example of electronic equipment, there is a proximity sensor that detects a proximity state of an object using a magnetic field generated by a coil. Such a proximity sensor has a structure in which an electronic circuit and an oscillation coil (hereinafter, referred to as a coil) are mounted on a resin-molded circuit case, and the circuit case is built in a metal housing having a partly opened surface. .

Hereinafter, the structure and assembling method of the above-described conventional proximity sensor will be described. FIG. 5 is a sectional view showing an assembly structure of the proximity sensor 50 of the first conventional example. The circuit case 51 is a box-shaped resin molded product that holds the electronic circuit 52 and the coil 53. The metal housing 54 is a prism-shaped housing having a recess. The metal housing 54 includes the electronic circuit 52.
And the circuit case 51 to which the coil 53 is attached, and also functions as an attaching portion when attaching the proximity sensor 50 to an object.

In order to assemble the proximity sensor 50 composed of such components, a circuit case 51 is inserted into a metal housing 54 by press-fitting or the like, and a filling resin 55 for bonding is injected from an opening (not shown) and heated. Alternatively, the filling resin 55 is cured by the action of a catalyst.

FIG. 6 is a sectional view showing an assembly structure of a proximity sensor 60 according to a second conventional example. The circuit case 61 is a box-shaped resin molded product that holds the electronic circuit 62 and the coil 63. Its shape is different from that shown in FIG. 5 and is a stepped prismatic shape. The metal housing 64 has a prismatic outer shape, and is a flat housing whose inside is hollowed out. Unlike the one shown in FIG. 5, the upper part has no partition, and the lower part has an opening smaller in diameter than the inner diameter of the upper part.

[0006] To assemble the proximity sensor 60 composed of such components, the circuit case 61 is inserted from above the metal housing 64 by press fitting or the like. Then, the filling resin 65 is injected from the upper opening, and the filling resin 65 is cured by heating or the action of a catalyst.

[0007]

In the proximity sensor 50 having the structure as in the first conventional example, the thermal expansion coefficient of the metal housing 54 is different from the thermal expansion coefficients of the resin of the circuit case 51 and the filling resin 55. Therefore, when the proximity sensor 50 is used for a long time under various temperature environments, the metal housing 54 and the resin are easily peeled off by a heat cycle. When peeling occurs, water easily enters from a boundary surface between the metal housing 54 and the resin, and the insulation of the circuit unit is deteriorated.

In the proximity sensor 60 having the structure as in the second conventional example, since the inner surface of the metal housing 64 and the filling resin 65 are not in direct contact with each other, the metal housing 64 and the circuit case 61 are not in contact with each other.
Adhesive force does not work between. For this reason, the circuit case 61 may come off from the metal housing 64, so that it is necessary to mechanically engage. This engagement mechanism has a drawback that it is difficult to reduce the size of the proximity sensor. Further, when the engagement mechanism having the above function is provided, there is a problem that the unit cost of parts increases, and the workability of assembly is impaired.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and has a structure in which a metal housing is sandwiched between a circuit case and another resin molded member, thereby improving the assembling workability. It is another object of the present invention to realize an electronic device that operates stably even in a severe temperature environment.

[0010]

According to a first aspect of the present invention, there is provided a resin-made circuit case which is formed in a box shape, has an engaging portion on an outer peripheral side wall thereof, and holds a circuit portion including a coil. A metal case that is formed in a frame shape and covers an outer peripheral side wall of the circuit case; and an upper plate that shields an internal space of the circuit case with the case interposed therebetween, and has an engagement portion with the engagement portion of the circuit case. A resin cover formed with a mating engaging portion, and filling and curing the filling resin in a gap formed when the circuit case, the housing, and the cover are fitted to each other. Thus, the circuit case and the cover are bonded to each other with the housing interposed therebetween, and the circuit case and the cover are integrated with the housing.

According to a second aspect of the present invention, there is provided a resin circuit case formed in a box shape and holding a circuit portion including a coil, and a metal formed in a stepped frame shape and covering an outer peripheral side wall of the circuit case. And the circuit case is inserted into the inside of the housing, and a filling resin is filled and hardened into an inner space of an outer peripheral side wall of the circuit case and an upper step portion of the housing, thereby forming the circuit. The case is sandwiched between a case and a filling resin layer, and the circuit case is integrated with the case.

[0012]

(Embodiment 1) The structure of a proximity sensor according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a sectional view showing an assembly structure of the proximity sensor 10 according to the present embodiment. The circuit case 11 is formed in a box shape so as to hold the electronic circuit 12 and the coil 13, and has a bottom plate 11a and a side wall 11b.
The shape of the bottom plate 11a is the same as the shape of the end face of the metal casing 14 described later, and the outer diameter of the side wall 11b is
Smaller than the inner diameter of. An engagement hole 11c is formed in a part of the surface of the side wall 11b. The circuit case 11 having such a structure is formed of, for example, ABS resin.

The metal housing 14 is formed in a prismatic shape, and is a frame-shaped housing whose inside is hollowed out. The metal housing 14 is formed by, for example, zinc die-casting, and has a circuit case 1 therein.
2 and the side wall of the cover 15 are inserted. The cover 15 has an upper plate portion 15a and a side wall portion 15b in substantially the same manner as the circuit case 11.
have. The shape of the upper plate 15a is the same as the contour of the end face of the metal housing 14, and the outer diameter of the side wall 15b is substantially the same as the inner diameter of the metal housing 14. A wedge-shaped projection 15c is formed in a part of the side wall 15b at a position corresponding to the engagement hole 11c of the circuit case so as to face inward. The cover 15 having such a structure is also formed of, for example, ABS resin.

In order to assemble the proximity sensor 10 composed of such components, first, the bottom plate 1 of the circuit case 11 is assembled.
The electronic circuit 12 and the coil 13 are attached to 1a. Next, the circuit case 11 is fixed, and the metal housing 14 is inserted from above. At this time, the circuit case 11 is positioned so that a constant gap is formed between the inner peripheral surface of the metal housing 14 and the side wall 11b of the circuit case 11.

Next, a filling resin 16 is injected into the upper space of the circuit case 11. Then, the cover 15 is inserted from above, and the projection 15c of the cover 15 and the engagement hole 11c of the circuit case 11 are inserted.
And are engaged. At this time, the side wall portion 15b of the cover 15 and the inner wall of the metal housing 14 are press-fitted, and the metal housing 14
The device itself is sandwiched between the circuit case 11 and the cover 15.

When the filling resin 16 is cured, the side wall 11b of the circuit case 11 and the upper plate 15
a between the circuit case 11 and the cover 1.
5 do not come off from each other with the metal housing 14 interposed therebetween. The filling of the filling resin 16 can also be performed by integrating the circuit case 11, the cover 15, and the metal housing 14 and then performing the injection through the opening for passing the cable.

According to such a configuration, the circuit case 11
The resin of the cover 15 and the resin of the cover 15 are bonded, so that even if expansion due to heating or shrinkage due to cooling occurs, no stress is generated on the bonding surface, and the resin does not peel off even for long-term use. . Further, it is not necessary to provide a mechanism for preventing the circuit case 11 and the cover 15 from being detached from the metal housing 14. Therefore, the component price of the metal housing 14 can be reduced,
Further, the overall shape of the proximity sensor 10 can be reduced. Further, since both the upper and lower surfaces of the proximity sensor 10 are covered with the molding resin, it is easy to display various marks and the operation center point. Furthermore, when the proximity sensor 10 is mounted on the detection object, the metal housing 14 does not contact the mounting surface, so that it is not necessary to newly provide an insulating sheet between the detection object and the proximity sensor 10.

(Embodiment 2) Next, the structure of a proximity sensor according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 2 is a sectional view showing an assembly structure of the proximity sensor 20 according to the present embodiment. The circuit case 21 has a box shape to which the electronic circuit 22 and the coil 23 are attached, and has a bottom plate 21a and a side wall 21b. The metal housing 24 is a frame-shaped housing formed in a prismatic shape, the inside of which is hollowed out in a stepped shape, and in which an upper portion 24a and a lower portion 24b are formed.
The metal housing 24 is formed by, for example, zinc die casting, and holds the circuit case 21 therein. The outer diameter of the bottom plate 21a of the circuit case 21 is the same as the inner diameter of the lower portion 24b of the metal housing 24, and the outer diameter of the side wall 21b is substantially the same as the inner diameter of the metal housing 24. The circuit case 21 having such a structure is integrally formed of, for example, an ABS resin.

To assemble the proximity sensor 20, the electronic circuit 22 and the coil 2 are mounted on the bottom plate 21a of the circuit case 21.
3 is attached. Next, the circuit case 21 is fixed, and the metal housing 24 is inserted from above. And the metal housing 24
The bottom plate portion 21a of the circuit case 21 is fitted to the lower step portion 24b.

Next, a filling resin 25 is injected into the upper space of the circuit case 21 and the upper portion 24a of the metal housing 24 and cured. After the filling resin 25 is cured, an adhesive force is generated on the side wall 21b of the circuit case 21, and the circuit case 21 and the filling resin 25 do not come off from each other with the metal housing 24 interposed therebetween. In this case, the housing components of the proximity sensor 20 are only the metal housing 24 and the circuit case 21,
The cover as in FIG. 1 is not required.

According to such a configuration, the filling resin 25 is adhered to the side wall 21b of the circuit case 21.
Even if expansion occurs due to heating or contraction occurs due to cooling, no stress is generated in this portion. Note that even if the adhesive strength between the filling resin 25 and the upper portion 24a of the metal housing 24 decreases due to long-term use, the circuit case 21 does not come off from the metal housing 24, and the hermeticity of the circuit portion including the coil 23 is reduced. Is secured. Further, similarly to the first embodiment, the metal housing 24
Therefore, there is no need to provide a resin retaining mechanism, and the cost of parts of the metal housing 24 can be reduced. Further, the shape of the proximity sensor 20 can be reduced.

(Embodiment 3) Next, a more specific embodiment of the components of the proximity sensor according to Embodiment 1 will be described in Embodiment 3.
This will be described below. FIG. 3 is a sectional view showing the structure of the proximity sensor 30 according to the present embodiment, and FIG. 4 is an exploded perspective view. As shown in FIG. 3, the proximity sensor 30 includes a circuit case 31, an electronic circuit 32, a coil 33, and a metal housing 3.
4, including the cover 35 and the filling resin 36. FIG. 3 shows a cross-sectional shape of the proximity sensor 30 when the proximity sensor 30 is cut vertically at a position including the engagement portion, that is, through the line XX shown in the lower part of FIG.

As shown in the lower part of FIG. 4, the circuit case 31 is roughly divided into a bottom plate portion 31a and a side wall portion 31b. The bottom plate portion 31a is fitted into the lower portion of the metal housing 34, and is a plate-like member slightly larger than the outer shape of the side wall portion 31b. The side wall portion 31b is formed in a shape to be inserted into the frame of the metal housing 34, and has an engaging portion 31c and a cable outlet 31d.

The engaging portion 31c is provided with a part of the side wall portion 31b.
A notch is formed at the center, and an engaging hole 3
1e is provided. The engagement hole 31e engages with the engagement portion of the cover 35 by snap fit, and the cover 35
Has the effect of locking the The cable outlet 31d is
An outlet for passing the cable 37. The circuit case 31 having the above structure is formed of, for example, ABS resin.

As shown in the middle part of FIG. 4, the metal housing 34 has a prismatic outer shape, and is a frame-shaped housing whose inside is hollowed out except for the mounting portion 34a. For example, 2
Two attachment holes 34b are formed, and are used when attaching the proximity sensor 30 to an object. In addition, metal housing 34
The upper part 34c is partially formed on the inner upper part of the frame forming, and the lower part 34d is formed over the entire lower part on the inner lower part of the frame. Metal housing 3 having such a structure
4 is formed by, for example, zinc die casting.

The cover 35 is placed on the upper portion 34c of the metal housing 34 as shown in the upper portion of FIG. 4, and has an upper plate portion 35a having substantially the same shape as the outer shape of the side wall portion 31b of the circuit case 31;
It is a plate-shaped member having an engaging portion 35b. Engagement part 35b
Is a tongue-shaped member which is formed slightly downward from the outer periphery of the upper plate portion 35a and has a wedge as shown in FIG.
This wedge is engaged with the engagement hole 31e of the engagement portion 31c. The cover 35 having such a structure is also formed of, for example, ABS resin.

To assemble the proximity sensor 30 composed of such components, the bottom plate 31a of the circuit case 31 is required.
Then, a printed circuit board on which the coil 33 and the electronic circuit 32 are mounted is attached. Then, one end of the cable 37 is passed through a cable outlet 31d, and the cable 3 is connected to a terminal of the electronic circuit 32.
7 are connected by soldering.

Next, the metal housing 3 is placed from above the circuit case 31.
Insert 4. At this time, the outer peripheral portion of the bottom plate portion 31a hits the lower portion 34d of the metal housing 34, and the cable outlet 31
By fitting d into the notch of the metal housing 34, both parts are positioned at fixed positions. Then, the cover 35 is fitted to the metal housing 34. At this time, the upper plate 35 of the cover 35
When “a” is pressed until it hits the upper portion 34 c of the metal housing 34, the engaging portion 35 b engages with the engaging portion 31 c of the circuit case 31, and the cover 35 and the circuit case 31 are connected with the metal housing 34 interposed therebetween.

Next, the cable outlet 31 of the circuit case 31
The filling resin 36 is injected from d and cured. Then, as shown in FIG. 3, the circuit case 31 and the cover 35 are adhered, and the circuit portion including the coil 33 is completely shielded from the outside.

When the proximity sensor 30 is assembled in such a process, no stress is generated between the resins even in the case of thermal expansion due to heating and contraction due to cooling. Circuit case 3
1 does not come off from the metal housing 34, and the sealing performance of the circuit section including the coil 33 does not deteriorate even if the environmental temperature changes due to long-term use. Further, since the filling resin 36 is not exposed, the appearance of the proximity sensor is improved in appearance. A wedge is provided on the engaging portion 35b of the cover 35, and the engaging hole 31 is formed on the side wall 31b of the circuit case 31.
Although e is provided, the location where the wedge and the engagement hole are formed may be reversed.

Although each of the embodiments described above relates to a proximity sensor, the present invention is not limited to the proximity sensor.
It goes without saying that the present invention can be applied to other electronic switches and electronic devices.

[0032]

According to the first aspect of the present invention, even when the electronic device is used under a severe temperature cycle, the circuit case does not come off from the metal housing, and the circuit portion is kept hermetically sealed. Further, the cost of the components can be reduced, and the assemblability can be improved. Further, since both surfaces are covered with the resin, an insulating sheet is not required when the proximity sensor is attached to the detection object.

According to the second aspect of the present invention, even if the electronic device is used under a severe temperature cycle, the circuit case does not come off from the metal housing, and the circuit portion is kept hermetically sealed. Further, the number of components can be reduced, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a proximity sensor according to Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view illustrating a structure of a proximity sensor according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a structure of a proximity sensor according to a third embodiment of the present invention.

FIG. 4 is an exploded perspective view showing a method of assembling a proximity sensor according to a third embodiment.

FIG. 5 is a cross-sectional view illustrating a structure of a proximity sensor of a conventional example (part 1).

FIG. 6 is a cross-sectional view illustrating a structure of a proximity sensor of a conventional example (part 1).

[Explanation of symbols]

 10, 20, 30 Proximity sensor 11, 21, 31 Circuit case 11a, 21a, 31a Bottom plate portion 11b, 15b, 21b, 31b Side wall portion 11c, 31e Engagement hole 12, 22, 32 Electronic circuit 13, 23, 33 Coil 14 , 24, 34 Metal housing 15, 35 Cover 15a, 35a Upper plate 15c Projection 16, 25, 36 Filled resin 24a, 34c Upper step 24b, 34d Lower step 31c, 35b Engagement section 31d Cable outlet 34a Mounting section 34b Mounting section Hole 37 Cable

[Procedure amendment]

[Submission date] June 11, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

[0010]

The present invention of claim 1 SUMMARY OF THE INVENTION is molded into a box shape, has an engaging portion on its peripheral side wall, times
A circuit case made of resin for holding the road portion , and a metal case formed in a frame shape and covering an outer peripheral side wall of the circuit case;
A resin cover having an upper plate portion that intercepts the internal space of the circuit case with the housing interposed therebetween, and a resin cover formed with an engaging portion that engages with the engaging portion of the circuit case; The circuit case, the housing, and the gap formed when the cover is fitted to each other, by filling and curing a filling resin, the circuit case and the cover are adhered to each other with the housing interposed therebetween. The circuit case and the cover are integrated with the housing.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

According to a second aspect of the present invention, there is provided a resin circuit case formed in a box shape and holding a circuit portion , and a metal housing formed in a stepped frame shape and covering an outer peripheral side wall of the circuit case. In a state where the circuit case is inserted into the inside of the housing, the inside space of the outer peripheral side wall of the circuit case and the upper portion of the housing are filled and filled with the filling resin, so that the circuit case and the filling are filled. The circuit case is sandwiched between resin layers, and the circuit case is integrated with the case.

Claims (2)

[Claims] 1. A resin-made circuit case which is formed in a box shape, has an engaging portion on an outer peripheral side wall thereof, and holds a circuit portion including a coil, and a frame-shaped outer peripheral side wall of the circuit case. A resin cover having a metal housing to cover, and an upper plate portion interposing the housing to shield an internal space of the circuit case, and having an engagement portion to be engaged with the engagement portion of the circuit case. The circuit case, the housing, and the gap formed when the cover is fitted to each other, by filling and curing a filling resin, the circuit case and the circuit case sandwiching the housing An electronic device, wherein the circuit case and the cover are integrated with the housing by bonding the cover and the cover. 2. A circuit case formed of a box and holding a circuit portion including a coil, made of a resin, and a metal case formed in a stepped frame shape and covering an outer peripheral side wall of the circuit case. Then, in a state where the circuit case is inserted into the inside of the housing, a filling resin is filled and hardened in an inner space of an outer peripheral side wall of the circuit case and an upper portion of the housing, so that the circuit case and the filling resin layer form An electronic device, comprising: a housing; and the circuit case integrated with the housing.