JP2889893B2 - Proximity switch and method of manufacturing the same - Google Patents

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 a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, by using an integrating circuit based on a value of a capacitance that changes as an object approaches,
Proximity switches that detect the approach of an object are often used. This capacitance type proximity switch is generally configured as shown in FIG.
The configuration shown in FIG.

FIG. 9 is specifically explained.
01, the detection electrode 102 disposed on the bottom 101A
Circuit board 10 having control circuit section by lead wire 103
4 and the circuit board 104 is connected to the resin case 1
01 is fixed and positioned by a fixing boss (not shown) provided inside. And the circuit board 10
Shield plate 1 which also functions as a counter electrode forming a capacitance component by being arranged opposite to detection electrode 102 so as to surround sensor 4.
05 are provided, and the circuit board 104 and the shield plate 105 are provided.
An insulating sheet material 106 is disposed between the two. The tip of the cable 107 for supplying power to the circuit board 104 and outputting the detection state is connected to the resin case 101.
And soldered to the circuit board 104.
Further, a resistor 108 for setting a detection area of the proximity switch is provided on the shield plate 105, and is soldered to the circuit board 104 via a lead 108A. In the resin case 101, in order to stabilize the detection output with respect to changes in ambient temperature and humidity, and to secure a mounting location for the resistor 108, a foaming resin 109 is formed from the bottom 101A to the lower surface of the circuit board 104. In addition, the non-foamable resin 110 is filled from the lower surface of the circuit board 104 to the upper surface 101B of the resin case 101 in order to secure oil resistance and water resistance.

Here, the role of the resistor 108 will be described in detail. As described above, before and after filling the area from the bottom 101A to the lower surface of the circuit board 104 with the foamable resin 109, the shield plate 1 serving also as the detection electrode 102 and the counter electrode is provided.
The capacitance during the period of the circuit board 1
The detection area set in step 04 and the actual detection area are shifted. In order to correct the displacement of the detection area, that is, to correct the value of the capacitance changed by the filling of the foaming resin 109, the resistor 108 is appropriately selected and the displacement is corrected.

[0005]

However, in the above-mentioned device, since the foaming resin is filled between the detection electrode and the shield plate, even if a proximity switch having the same shape is manufactured, the gap between the detection electrode and the shield plate is reduced. Will vary in the capacitance value. This variation in the value of the capacitance is due to the fact that the ratio of the gas contained in the foamable resin is not constant. Therefore, in order to correct the scattered capacitance, it is necessary to prepare in advance a very large number of types of correction resistors corresponding to the respective variations, and maintenance and management of the resistors have been difficult. .

Further, in the above-mentioned device, since the foaming resin is filled only from the bottom of the case to the lower surface of the circuit board in order to secure a place for attaching a lead for connecting a resistor to the circuit board, the shield plate is fixed. When filling the non-foamable resin after correcting the detection area by resistance, the non-foamable resin enters between the circuit board and the shield plate, or the shield plate is deformed by the influence of the resin. Therefore, there is also a problem that the capacitance changes again and the detection area shifts, and the correction by the resistance becomes meaningless.

In addition, since the resistor is provided on the shield plate via the lead, there is a problem that noise easily gets on the lead.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the variation in capacitance when a resistor is mounted, to set a detection area accurately by the resistance, and to mount the resistor even when filled with resin. An object of the present invention is to provide a proximity switch capable of performing detection.

[0009]

According to the present invention, a detection electrode is disposed on a bottom surface in an insulating case, is disposed in a direction facing the detection electrode, and is electrically connected to the detection electrode. Disposing a substrate provided with a circuit in the insulating case; providing a seal member defining a desired region on a surface of the substrate opposite to a surface facing the detection electrode; Providing a counter electrode forming a capacitive component by disposing the counter electrode on the substrate via the seal member, and a region between the bottom surface and the counter electrode in the insulating case is formed of an insulating resin. A step of filling, a step of providing a resistor for setting the detection area of the detection electrode to a desired value in the desired area, and a step of placing the insulating resin, the counter electrode, the resistor, and the substrate in the insulating case. By having a step of forming a resin layer on a region, it has achieved the above objects.

A detection electrode disposed on a bottom surface in the insulating case; and a circuit electrically connected to the detection electrode. The detection electrode is installed in the insulating case in a direction facing the detection electrode. A substrate, a seal member that defines a desired region on a surface of the substrate opposite to the surface facing the detection electrode, and a seal member provided on the substrate with the seal member interposed therebetween; A counter electrode that forms a capacitance component by being disposed, a non-foamable resin that is formed in a region between the bottom surface and the counter electrode in the insulating case, and is provided in the desired region; A resistor for setting the detection area of the detection electrode to a desired value, and the non-foamable resin in the insulating case, the counter electrode, the resistor, and a resin layer formed on a desired area of the substrate are provided. By the above eye It has achieved.

The resistor is preferably a thin chip resistor.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to one embodiment shown in the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes an insulating case, which is made of plastic in this embodiment, and has a bottom surface 1a on which a detection surface 2a of a detection electrode 2 having a U-shaped cross section is fixed. The feet 2b of the detection electrodes 2 are soldered to and electrically connected to a substrate 4 having various circuits 3. The substrate 4 is provided with various circuits 3 on the surface facing the detection electrode 2, and is fixed to the case 1. Substrate 4
A seal member 5 is provided on the upper surface of the drawing, and a shield portion 6 made of brass or the like and constituting a counter electrode is disposed to face the detection electrode 2 with the seal member 5 interposed therebetween.
It is provided so as to surround and shield. In this example, an annular member made of rubber is used as the seal member 5, and an area 5a inside the ring is defined as a resistance fixing area. The shield portion 6 has a hole 6a having the same shape as the inner surface of the seal member 5 and a hole 6b for a lead 9a of a cable 9 to be described later, as shown in FIG. Form. A chip resistor 7 for correcting the detection area is provided in the area 5a. The chip resistor 7 is connected to an integration circuit formed by a capacitance component formed by the detection electrode 2 and the shield portion 6 and a resistor (not shown), and is filled with a non-foamable resin 8 described later. A time constant that changes according to a change in the capacitance of the capacitance component formed by the fluctuating detection electrode 2 and the shield unit 6 is corrected. The method of detecting an object in the present example is performed by using an integrating circuit (not shown) having a predetermined time constant, and having a capacitance component formed by the detection electrode 2 and the shield portion 6 and having the time constant determined by the proximity of the object. Input a common pulse to the integrator circuit that fluctuates, and by the magnitude of the difference in the delay time of this pulse,
It detects the approach of an object such as a human body. Since the chip resistor 7 is provided directly on the substrate 4 as described above, it is possible to eliminate a lead on which noise is apt to ride, and to reduce the size and thickness of the configuration. A region between the bottom 1a of the case 1 and the upper surface of the shield 6 is filled with an insulating non-foamable resin 8 (in this example, an epoxy resin is used). As described above, by filling the insulating non-foamable resin 8, the detection output can be stabilized against a change in ambient temperature and humidity. Since the non-foamable resin 8 does not contain a gas, the displacement of the detection area of the detection electrode 2 due to filling the gas is stabilized at substantially the same value as long as the filling shape is the same. Therefore, it is not necessary to prepare many types of chip resistors 7 for correcting the detection area shifted by the filling of the non-foamable resin 8 unlike the related art, and the cost at the time of assembly can be reduced. Reference numeral 9 denotes a cable, which is soldered to the substrate 4 by a lead 9a, supplies power to various circuits 3 provided on the substrate 4, detects an approach of an object such as a human body, and outputs a detection signal. . Reference numeral 10 denotes a non-foamable resin layer (in this example, an opaque epoxy resin containing 1% carbon is used), which is provided on the region 5a, the shield portion 6, the chip resistor 7, and the non-foamable resin 8. is there.

Next, a method of manufacturing the proximity switch shown in FIG. 1 will be described.

The foot 2b of the detection electrode 2 is soldered to the surface of the substrate 4 on which the various circuits 3 are mounted, and the detection electrode 2 and the various circuits 3 are electrically connected.

The detection electrode 2 and the substrate 4 which are electrically connected to each other
Are fixed in the case 1. At this time, the bottom 1a of the case 1 and the detection surface 2a of the detection electrode 2 are arranged so as to be in close contact with each other.

On the surface of the substrate 4 opposite to the surface facing the detection electrode 2, a seal member 5 defining a position 5a for mounting the chip resistor 7 is disposed.

A shield portion 6 is provided so as to surround the substrate 4 with a seal member 5 interposed therebetween, and to face the detection electrode 2.

By screwing (not shown) from above the shield part 6 (from the top down in FIG. 1), the substrate 4,
The seal member 5 and the shield part 6 are fixed to the case 1. Therefore, the seal member 5 is pressed against the substrate 4 by the shield part 6.

The lead 9a of the cable 9 is soldered to the substrate 4 to connect the cable 9 to the cable guide portion 1b of the case 1.
Fixed to.

The region from the bottom 1a of the case 1 to the upper surface of the shield 6 is filled with a non-foamable resin 8 (in this example, an epoxy resin is used). In this case, the sealing member 5
As a result, the non-foamable resin 8 does not enter the region 5a for providing the chip resistor 7 for correcting the displacement of the detection region.
The non-foamable resin 8 can be completely filled up to the upper surface of the shield portion 6. Therefore, there is no air between the bottom 1a and the upper surface of the shield 6, and the shield 6 can be completely fixed, so that the variation in capacitance can be reduced. In other words, there is no possibility that the resin or the like will intrude into a region that is greatly related to the change in the capacitance value, and there is no possibility that the shield portion 6 will be deformed. There is no possibility that the capacitance greatly changes after the filling of.

When the filling of the non-foamable resin 8 is completed, a chip resistor 7 having a resistance value corresponding to the capacitance between the shield portion 6 and the detection electrode 2 determined by the filling of the resin 8 is provided in the region 5a. It is installed so as to have a desired detection area (see FIG. 2). When the chip resistor 7 is provided, as described above, the charged resin is a non-foaming resin and does not contain air, so that the change in capacitance due to the filling of the resin 8 becomes a constant value to some extent. It is sufficient to prepare only the corresponding chip resistor 7, so that the trouble of preparing the extra resistor can be eliminated, and the cost for preparing the extra resistor can be reduced. Since the chip resistor 7 is provided directly on the substrate 4, noise can be removed as described above, and the structure can be reduced in size.

When the mounting of the chip resistor 7 is completed, the non-foamable resin 10 (in this example, epoxy resin containing 1% carbon is used) is applied to the region 5 a and the shield portion 6.
And the chip resistor 7 and the non-foamable resin 8 are filled to form a non-foamable resin layer 10. Even when the non-foamable resin 10 is filled, the space between the substrate 4 and the shield portion 6 is sealed by the seal member 5, so that the non-foamable resin 10 enters between the detection electrode 2 and the shield portion 6. Never. That is, after the detection area is corrected by the chip resistor 7, it is possible to prevent the detection area from shifting due to the change in the capacitance of the capacitance component again.

As described above, after the sealing member 5 is provided on the substrate 4, the shield part 6 is provided via the sealing member 5,
Thereafter, the area between the case bottom 1a and the shield part 6 is filled with a non-foamable resin, so that the mounting position of the resistor 7 is secured while the capacitance component between the detection electrode 2 and the shield part 6 is maintained. There is no possibility that the resin or the like will intrude into the region, that is, the region that is greatly related to the value of the capacitance of the capacitance component. That is, the value of the capacitance of the capacitance component formed by the detection electrode and the counter electrode can be determined.

Further, since the area between the case bottom 1a and the shield section 6 is filled with the non-foamable resin 8, the detection area is set to a desired value by the resistor 7, so that the detection area can be surely corrected. .

Further, when forming the non-foamable resin layer 10 on the non-foamable resin 8, the shield 6, the resistor 7, and the region 5 a of the substrate 4, the resin 10 is moved between the shield 6 and the substrate 4. The detection area does not shift after the resistor 7 is provided since the sealing member 5 prevents the intrusion of the detection member.

In the above example, an annular seal member is used. However, the present invention is not limited to the above. For example, the seal member may be formed into a sheet-like member as shown in FIG.
A shape having a lead connection region 5b may be used, or a cylindrical protrusion 5c may be provided in the chip resistance formation region 5a of FIG. 3 as shown in FIG. FIG.
4 is an explanatory view in the case where the sealing member shown in FIG. 4 is used. Since the non-foamable resin 10 does not enter the region 5a as shown in FIG. And the like, and the non-foamable resin 10
Subtle shift in the detection area caused by contact with the chip resistor can be eliminated. In this case, it is desirable to provide the stopper 11 in the cylindrical portion so that moisture does not enter the cylinder.
In FIG. 5, the components having the same numbers as those in FIG. 1 are the same.

In order to improve the sealing performance of the sealing member 5, as shown in FIGS.
d may be provided, or a protrusion 6a may be provided at a portion of the shield portion 6 which engages with the seal member 5, as shown in FIG.

In this embodiment, the detection area is corrected by mounting a chip resistor. However, the detection area may be corrected by mounting a variable resistor and adjusting the variable resistance.

Further, according to the manufacturing method of the present invention, since the sealing member 5 is provided, the resin to be filled first may be a foamable resin, and the resin to be charged secondly may be formed of the shield part 6 and the substrate 4. Can be eliminated.

[0031]

According to the present invention, after providing a seal member for defining a desired area of the substrate, a counter electrode is provided via the seal member, and then a gap between the bottom of the case and the counter electrode is formed with an insulating resin. In this case, the counter electrode can be fixed, and the sealing member prevents the insulative resin from invading the mounting location of the resistor. As a result, the region between the capacitance components formed by the detection electrode and the counter electrode, that is, the region largely related to the capacitance value of the capacitance component is filled in a later step. The inconvenience that the capacitance fluctuates due to the intrusion of resin or the like can be solved.

Since the area between the bottom of the case and the counter electrode is filled with an insulating resin and the resistance is used to set the detection area to a desired value, the detection area can be set accurately.

Since the chip resistor for correcting the detection area is provided on the substrate, it is possible to eliminate the lead, which has conventionally been easy to carry noise, to improve the detection performance, and to further reduce the size of the configuration. In addition, the thickness can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is a plan view showing a part of the manufacturing process of the manufacturing method of the present invention.

FIG. 3 is a perspective view showing another embodiment of the seal member used in the present invention.

FIG. 4 is a perspective view showing another embodiment of the seal member used in the present invention.

FIG. 5 is a sectional view showing another embodiment of the present invention.

FIG. 6 is a sectional view showing another embodiment of the seal member used in the present invention.

FIG. 7 is a sectional view showing another embodiment of the seal member used in the present invention.

FIG. 8 is a sectional view showing another embodiment of the counter electrode used in the present invention.

FIG. 9 is a sectional view showing a configuration of a conventional proximity switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating case 2 Detection electrode 3 Circuit 4 Substrate 5 Seal member 6 Counter electrode 7 Resistance 8 Insulating resin, non-foaming resin 10 Resin layer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01H 11/00 H01H 36/00

Claims (3)

(57) [Claims] A detection electrode is disposed on a bottom surface in an insulating case, and a substrate provided with a circuit disposed in a direction facing the detection electrode and electrically connected to the detection electrode is provided on the bottom surface of the insulating case. Disposing the sealing member defining a desired area on a surface of the substrate opposite to the surface facing the detection electrode; and providing a capacitance component by disposing the substrate facing the detection electrode. Forming a counter electrode on the substrate via the seal member, filling the area between the bottom surface and the counter electrode in the insulating case with an insulating resin, Providing a resistor for setting the detection area to a desired value in the desired area; and the insulating resin in the insulating case, the counter electrode,
Forming a resin layer on a desired region of the resistor and the substrate. 2. A detection electrode disposed on a bottom surface in an insulating case, and a circuit electrically connected to the detection electrode, and installed in the insulating case in a direction facing the detection electrode. A substrate, a seal member defining a desired area on a surface of the substrate opposite to the surface facing the detection electrode, and a detection member provided on the substrate via the seal member. And a non-foamable resin formed in a region between the bottom surface and the counter electrode in the insulating case; and a non-foamable resin formed in the desired region. A resistor for setting a detection region of the detection electrode to a desired value; and a resin layer formed on a desired region of the non-foamable resin, the counter electrode, the resistor, and the substrate in the insulating case. Characterized by having Proximity switch. 3. The proximity switch according to claim 2, wherein the resistor is a thin chip resistor.