JPH081541Y2 - Proximity switch - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a proximity switch having excellent water resistance capable of safely sealing the internal structure even when the temperature environment changes.

[Conventional technology]

Conventionally, this type of proximity switch, which has a coil for detecting a metal body inside the casing, has been widely used in automation equipment and FMS, but it can be used in harsh temperature environments from + 70 ° C to -30 ° C. It was required to have a sufficient sealing ability.

In order to meet this demand, a switch as shown in FIG. 4 has been proposed. That is, in the proximity switch A, the detection coil D and the light emitting diode E are provided on the semiconductor substrate C having the electric circuit portion B, and the display body F is provided on one side and the cable G is provided on the other side. A casing H is formed by integrally molding the outer periphery of the cable with a resin, magnetically detecting the approach of the metal body to the detection coil D energized by an appropriate oscillating means, and then the cable G It was configured to take this out as an output signal.

[Problems to be solved by the invention]

In the conventional proximity switch A as described above, however, there is a risk that the sealing property of the electric circuit unit B, the detection coil D and the like may be impaired depending on the temperature change of the usage environment.

That is, in the proximity switch A having this configuration, due to the difference in the thermal contraction rate between the resin material and the display body F due to the temperature change in the usage situation, a gap is generated on the contact surface f due to peeling. A phenomenon was observed, and there was a serious drawback that moisture penetrates into the interior through the voids and damages not only the detection coil D but also the electric circuit section B and the like.

Therefore, it has been desired to provide an excellent proximity switch that does not impair the hermeticity of the circuit structure or the like under any temperature change condition.

[Means and actions for solving problems]

This invention can provide a proximity switch that can sufficiently meet such a demand, and is characterized in that a detection coil and an LED are connected and arranged on a semiconductor substrate having an electric circuit section. , The LED display body is provided with a recessed reduced diameter portion whose cross-sectional shape is symmetrical with respect to the orthogonal direction and which has a rounded outer periphery, together with the semiconductor substrate, the detection coil and the LED. , A casing is formed by integrally surrounding and molding a resin material so that only the display body is partially exposed.
Since the lip portion of the casing is tightly intruded into the recessed reduced diameter portion so that the display body and the casing are in close contact with each other in a non-separable manner, the proximity switch is formed. Not only the stress due to molding shrinkage is made uniform, but even under conditions that contribute to heat cycle under severe temperature conditions, shrinkage due to temperature change occurs evenly between resin materials, resulting in uneven stress on the contact surface. As a result, there is no peeling phenomenon between the casing made of resin material and the display body, and it is possible to obtain a proximity switch that is excellent in water resistance and has few failures over a long period of time. Is something that can be done.

〔Example〕

Next, the invention will be described with reference to the drawings showing an embodiment thereof.

As shown in FIGS. 1 and 2, the detection coil 3 is arranged on one side of the semiconductor substrate 2 having the electric circuit section 1, and the LED (light emitting diode) 4 is arranged on the other side.
A translucent display body 5 of a desired color such as polyarylate is fitted so as to cover the ED4, and a cable 6 connected to the electric circuit section 1 is arranged on the other side of the semiconductor substrate 2. The display body 5 is provided with a recessed reduced diameter portion 5A partially forming a step, and the recessed reduced diameter portion 5A has a circular cross-sectional shape or a direction orthogonal thereto. It has a symmetrical elliptical or polygonal shape, and its outer periphery is configured so that the corners are rounded.

In such an assembled state, by inserting this into a mold body M, N as shown by a dashed line and injecting a thermoplastic resin material such as polycarbonate to integrally mold the casing 7, The semiconductor substrate 2, the detection coil 3 and the LED 4 are enclosed inside, and the display body 5 is embedded in a partially exposed state.

In particular, at the time of this molding processing, the thermoplastic resin material penetrates into the recessed reduced-diameter portion 5A and enters the lip portion of the casing 7.
7A is formed, and the lip portion 7A comes into close contact with the display body 5.

In addition, this detection coil 3 has a third
As shown in the figure, it is excited by an oscillating circuit 9 energized by a power source 8 and magnetically reacts to the approach of the metal body P, and its output is detected by a detection circuit 10 and an amplification circuit. A detection signal 12 having a desired capability can be communicated via 11 and a visual signal can be transmitted from the display 5 by the light emission of the LED 4.

In the present embodiment having the above-described structure, the display body 5 and the casing 7 configured to cover the display body 5 have the recessed reduced diameter portion 5A and the lip portion 7A of the casing 7 in close contact with each other. Since the recessed reduced-diameter portion 5A is invaded and has a circular cross section or a symmetrical rounded outer shape with respect to the orthogonal direction, the casing 7 and the display body 5 made of a thermoplastic resin. In addition to the fact that each molding shrinkage phenomenon occurs uniformly, uneven stress does not concentrate on the mutual contact interface, and there is no risk of peeling between them, Even if different heat shrinkage occurs between the display body 5 and the casing 7 when the proximity switch is repeatedly used as a heat cycle in a severe environment near −30 ° C. or + 70 ° C. The interface of is the lip of the casing 7.
The labyrinth-like structure is formed by 7A and the recessed reduced-diameter portion 5A of the display body 5, and the distance is also long, and water such as water or moisture is casing. Intruding into 7 electric circuit section 1, detection coil 3, LED4
There is no danger of damaging such things.

[Effect of device]

As described in detail in the above embodiments, the present invention is based on the electrical circuit section, the detection coil and the LED in the proximity switch.
Etc. are enclosed in a sealed state by a resin casing, and in particular, the cross-sectional shape of the recessed reduced diameter portion of the partially enclosed display is circular or symmetrical with respect to the orthogonal direction. In addition, since the surface has a rounded shape, the recessed reduced diameter portion of the display body which constitutes the proximity switch and the lip portion of the casing intruded into this are firmly adhered. Therefore, it is possible to exert the effect that there is no risk of moisture entering the casing and damaging the internal detection coil, etc., and in addition, in terms of thermal changes in the operating environment of the proximity switch, Even if it is severe as described above, it is possible to exert an excellent effect that the peeling phenomenon that causes the functional failure is not observed at the mutual contact interface.

[Brief description of drawings]

FIG. 1 shows an A in FIG. 2 of the proximity switch of the present invention.
2 is a plan view thereof, FIG. 3 is a circuit block diagram, and FIG. 4 is a partial sectional view of a conventional example. 1 ... Electrical circuit 2 ... Semiconductor substrate 3 ... Detection coil 4 ... LED 5 ... Display 6 ... Cable 7 ... Casing

Claims (1)

[Scope of utility model registration request] 1. A detection coil and an LED are connected to each other and arranged on a semiconductor substrate having an electric circuit section, and a cross-sectional shape of a display body of the LED is symmetrical with respect to an orthogonal direction,
Moreover, a recessed reduced diameter portion having a rounded outer periphery is provided, and together with the semiconductor substrate, the detection coil and the LED,
A casing is formed by integrally surrounding and molding a resin material so that only the display body is partially exposed,
At this time, the proximity switch is configured such that the lip portion of the casing is tightly intruded into the recessed reduced diameter portion and the display body and the casing are in close contact with each other in a non-separable manner.