JP4691439B2 - Detection sensor - Google Patents

Description

  The present invention relates to a detection sensor.

In the detection sensor, a light emitting element for displaying the operation state is accommodated in the case, and a transparent resin is used for a part of the case so that the user can visually recognize the operation state (detection state). What is composed is known.
Also, many of the detection sensors, such as proximity sensors, are used in factory production lines, and in general, the light emitting element portion or the like is provided so that no trouble occurs even when machine oil or cleaning liquid is received. It is necessary to cover with a case made of a resin having oil resistance and chemical resistance.
In the following Patent Document 1, a case comprising a transparent synthetic resin cap that covers the light emitting element portion and an opaque synthetic resin that covers the circuit board portion excluding the cap is provided for the circuit board to which the light emitting element is attached. An improved detection sensor is disclosed.
Japanese Utility Model Publication No. 61-202840

By the way, in general, in the case of the detection sensor, an opaque synthetic resin portion is made of a crystalline plastic (PBT or the like), and a transparent synthetic resin portion that transmits light from a light emitting element is made of an amorphous plastic. (PC etc.) is used. Here, the non-crystalline plastic and the crystalline plastic are difficult to fuse with each other, so that it is difficult to have adhesion during molding (it is difficult to provide adhesion at the joint between the non-crystalline plastic and the crystalline plastic). Because it is difficult to sufficiently seal the interior with the case, there is a problem in water resistance (penetration of machine oil, etc.) at the boundary portion between the amorphous plastic and the crystalline plastic (gap between the joint portions). There is a fear.
This invention is completed based on the above situations, Comprising: It aims at providing the detection sensor which can improve the sealing performance of a case.

As means for achieving the above object, a detection sensor according to the invention of claim 1 includes a detection unit that performs a detection operation in accordance with a detection state of an object to be detected, and a light emission operation in accordance with the detection operation of the detection unit. A detection sensor including a case that covers the operation display unit, and a case that covers the operation display unit is formed of a light- transmitting resin. The range not covered with the transparent resin is formed of the first alloy resin in which the amorphous plastic is mixed with the crystalline plastic, and the range of the light transparent resin that covers the operation display unit includes a plurality of types of amorphous resins. A second alloy resin in which a functional plastic is mixed. The second alloy resin is characterized in that polyester and polycarbonate are used .

  According to a second aspect of the present invention, in the first aspect, the non-crystalline plastic in the first alloy resin and the non-crystalline plastic constituting the light-transmitting resin that covers the operation display unit are the same. It is characterized by being.

  According to a third aspect of the present invention, there is provided the first alloy resin according to the first or second aspect, wherein the first alloy resin has a higher mixing ratio of the crystalline plastic and the amorphous plastic than the crystalline plastic. It has the characteristics.

The invention of claim 4 is characterized in that, in the invention according to any one of claims 1 to 3 , the second alloy resin is characterized in that the polyester has a higher mixing ratio than the polycarbonate .

A fifth aspect of the present invention, there is provided a connector described in any one of claims 1 to 4, a first alloy resin used in the range not covered with the optically transparent resin is polyethylene terephthalate as a crystalline plastic It is characterized by the fact that polycarbonate is used as the amorphous plastic.

<Invention of Claim 1>
A light-transmitting resin made of an amorphous plastic is used in the detection sensor case so as to be visible from the outside in the range covering the operation display unit. However, non-crystalline plastic is generally inferior in oil resistance and chemical resistance, so in a detection environment that requires oil resistance and chemical resistance, it is non-crystalline as a light transmissive resin that covers the operation display section. In the range where plastic is used and not covered with the light-transmitting resin, crystalline plastics having excellent oil resistance and chemical resistance are used.
By the way, the non-crystalline plastic and the crystalline plastic are difficult to fuse with each other, so that it is difficult to have adhesion at the time of molding, and the water resistance at the boundary between the non-crystalline plastic and the crystalline plastic (gap between the joint portions) is improved. Problems may arise.
Therefore, according to the present configuration, the area not covered with the light-transmitting resin is formed of the first alloy resin in which the amorphous plastic is mixed with the crystalline plastic. When the non-crystalline plastic in the first alloy resin is fused, it becomes easy to adhere at the time of molding, and the sealing property of the case can be improved. Accordingly, it becomes difficult for machine oil or the like to enter from the outside, and water resistance can be further increased.
In addition, the non-crystalline plastic used as the light-transmitting resin in a range covering the operation display unit is a second alloy resin in which a plurality of types of non-crystalline plastics are mixed. The second alloy resin is made of polyester and polycarbonate. Used. Therefore, oil resistance can be imparted to the range covering the operation display unit, and the oil resistance of the entire detection sensor can be improved.
Furthermore, in general, an amorphous plastic is inferior in oil resistance and heat resistance as compared to a crystalline plastic, but it is desirable that the range covering the operation display portion is as high as possible in oil resistance and heat resistance.
Therefore, according to this configuration, an alloy resin in which polyester and polycarbonate are mixed with non-crystalline plastic covering the operation display unit is used. Therefore, oil resistance and heat resistance can be imparted to the range covering the operation display unit, and the oil resistance and heat resistance can be improved as a whole of the detection sensor.

<Invention of Claim 2>
According to this configuration, since the non-crystalline plastic is the same, the non-crystalline plastic is easily fused. Accordingly, the adhesion can be further improved.

<Invention of Claim 3>
In general, crystalline plastics are superior in oil resistance and heat resistance. Therefore, according to this configuration, since the mixing ratio of the crystalline plastic is larger than that of the amorphous plastic, oil resistance and heat resistance can be improved in a range not covered with the light transmissive resin.

<Invention of Claim 4 >
In general, the detection sensor is often used in an environment where oil resistance is required rather than heat resistance. Therefore, according to this configuration, the oil resistance can be improved, which is suitable for use in an environment where oil resistance is required.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS.
1. Configuration of Proximity Sensor The proximity sensor 10 of this embodiment (corresponding to the “detection sensor” of the present invention) is, for example, arranged on a production line of a factory, and is made of a metal workpiece W (“detected” of the present invention. Based on the change in the magnetic field of the detection coil 11 (corresponding to the “detection part” of the present invention) generated when the object is transported), the approach of the metal workpiece W and the presence / absence thereof are determined. In the following, the direction of the proximity sensor 10 will be described with the front side (upper side in FIG. 6) in FIG. 1 as the upper side and the left side in FIG. 1 as the front side.

(1) Configuration of Proximity Sensor FIG. 1 is a top view of the proximity sensor 10, and FIG. 2 is a bottom (bottom) view of the proximity sensor 10.
As shown in FIG. 1, the proximity sensor 10 includes a rectangular circuit board 31 (a dotted line portion in FIG. 1) on which the detection coil 11 and the like are mounted, and a rectangular parallelepiped protective case 50 that covers the entire circuit board 31 and the like. (Corresponding to the “case” of the present invention). When a metal workpiece is present in the axial direction of the detection coil 11 (the front side in FIG. 1), the magnetic field generated from the detection coil 11 changes, so that the metal workpiece is detected based on the change. Yes.

  On the circuit board 31, the detection coil 11 is mounted on the front end side (left end side in FIG. 1), while the connection terminal portion in which terminals 20 to 23 are arranged on the rear end (right end) side. 34 is provided. And each signal line of the signal cable 32 connected to an external apparatus is connected here.

  Further, a cylindrical sleeve 33 into which a mounting screw for attaching the proximity sensor 10 to a predetermined position is inserted so as to penetrate the upper and lower surfaces at a position slightly rearward from the center of the circuit board 31. Yes. An oscillation circuit 14, a detection circuit 15, an output circuit 17, and a sensitivity adjustment circuit 19, which will be described later, are mounted on a circuit pattern between the detection coil 11 and the terminals 20 to 23.

  In addition, as shown in FIG. 2, the light emitting element 16 for detection and the light emitting element 18 for stability confirmation are arranged in parallel at the front end of the back surface of the circuit board 31, and light emission is performed according to the detection state of the metal workpiece. The elements 16 and 18 emit light. Therefore, the light emitting elements 16 and 18 correspond to the “operation display unit” of the present invention.

  The protective case 50 has a rectangular parallelepiped shape, which will be described in detail later, but includes a light transmitting portion 51 made of a transparent resin that transmits light (or a translucent resin, which corresponds to the “light transmitting resin” of the present invention), and light. And a light shielding portion 52 made of an opaque resin that does not transmit.

The light shielding portion 52 is provided over substantially the entire protective case 50 except for a portion L1 (left end portion in FIG. 2) below the detection light emitting element 16 and the stability confirmation light emitting element 18 on the bottom surface of the protective case 50. Yes.
On the other hand, the translucent part 51 is a peripheral part excluding a part L1 below the light emitting elements 16 and 18 of the bottom surface of the protective case 50 and a bottom part of the central position (substantially middle part in the front-rear direction) of the protective case 50. (Both side walls and upper surface portion) L2 and a peripheral portion L3 of the connection terminal portion 34. That is, in FIGS. 1 and 2, the hatched portion is the light transmitting portion 51, and the other portion is the light shielding portion 52.

As a transparent resin for the light-transmitting portion 51, polyester (polyester resin), which is a light-transmitting amorphous plastic with relatively high oil resistance and low heat resistance, has low oil resistance and relatively high heat resistance. Thermoplastic alloy resin (PC / PE alloy, which is a light transmissive amorphous plastic) (equivalent to “second alloy resin” of the present invention. For example, XYLEX (Registered by General Electric Company) Trademark, trade name of GE Plastics)).
Here, the mixing ratio of polyester and polycarbonate is larger in polyester (amorphous plastic having oil resistance) than in polycarbonate (amorphous plastic having heat resistance). Therefore, since oil resistance can be improved, it can be used in an environment where oil resistance is required.

On the other hand, as a resin for the light shielding part 52, PBT (polybutylene terephthalate), which is a crystalline plastic that has excellent oil resistance and heat resistance and does not transmit light, has low oil resistance but relatively high heat resistance. Alloy (PC / PBT alloy, which corresponds to the “first alloy resin” of the present invention. For example, Xenoy (registered trademark of General Electric Company) GE Plastics trade name)).
Here, the mixing ratio of PBT (polybutylene terephthalate) and PC (polycarbonate) is larger in PBT (polybutylene terephthalate) which is a crystalline plastic. Thereby, the light-shielding part 52 has relatively oil resistance and heat resistance.

  In this way, oil droplets (machine oil) scattered in the production line or the like, cleaning liquid scattered in the food line, etc. on the light transmitting portion 51 (transparent resin) and the light shielding portion 52 (opaque resin) of the protective case 50. By using an alloy resin having oil resistance and heat resistance, adhesion between the light transmitting part 51 (transparent resin) and the light shielding part 52 (transparent resin) is provided while providing oil resistance and heat resistance. Therefore, the sealing property of the protective case 50 can be improved. Therefore, since water resistance can be given, oil droplets etc. reach components, such as the circuit board 31 accommodated in the inside of the protective case 50, and do not have a bad influence.

(2) Circuit Configuration of Proximity Sensor FIG. 3 is a block diagram showing a circuit configuration of the proximity sensor.
As shown in FIG. 3, the LC parallel circuit 13 including the detection coil 11 and the capacitor 12 is maintained in an oscillation state by the oscillation circuit 14, thereby generating an alternating magnetic field H (detection region H) from the detection coil 11. When the metal workpiece approaches in this oscillation state, the magnetic energy of the detection coil 11 is absorbed, and the amplitude voltage of the LC parallel circuit 13 changes (for example, decreases) accordingly. For example, the detection circuit 15 compares the amplitude voltage of the LC parallel circuit 13 with a predetermined detection threshold, and performs a detection operation based on the comparison result. In the present embodiment, as the detection operation, when the amplitude voltage of the LC parallel circuit 13 falls below the detection threshold value, the detection light emitting element 16 (for example, a light emitting diode that emits green light) as an operation indicator lamp emits light. The detection signal is output to the outside via the output circuit 17.

  The detection circuit 15 also compares the amplitude voltage of the LC parallel circuit 13 with a stability confirmation threshold value that is higher than the detection threshold value, and the amplitude voltage of the LC parallel circuit 13 exceeds the stability confirmation threshold value during the detection operation. When there is no more light, the light emitting element 18 for stability confirmation (for example, a light emitting diode that emits red light) emits light. Reference numerals 20 and 21 in FIG. 1 are a power supply terminal and a ground terminal for supplying power to the proximity sensor 10, and reference numeral 22 is an output terminal for outputting the detection signal from the output circuit 17 to an external device. It is. Reference numeral 23 denotes an input terminal for inputting, from an external device, a control signal connected to the oscillation circuit 14 and applied to the sensitivity adjustment circuit 19 for adjusting the amplitude voltage of the LC parallel circuit 13.

2. Proximity Sensor Manufacturing Method Next, a method of manufacturing the proximity sensor 10 will be described with reference to FIGS.
First, as shown in FIG. 4, the detection coil 11 and the like are soldered on the front surface of the circuit board 31, and the detection light emitting element 16 and the stability confirmation light emitting element 18 and the like are soldered to the back surface. Then, the sleeve 33 is fitted into the through hole 31a (see FIG. 2) formed in the circuit board 31.

  Next, as shown in FIG. 5, the light shielding portion 52 excluding the L1, L2, and L3 portions is primarily molded with an opaque resin. At this time, the reason why the peripheral portion L2 at the central position of the circuit board 31 is not resin-molded is that resin molding is performed while supporting the central portion L2 as well as the front-end portion L1 and the rear-end portion L3 of the circuit board 31. This is to suppress the warpage of the circuit board 31.

As a result, as the primary forming member 40 (light-shielding portion 52; opaque resin in the shaded area in FIG. 5), the portion covering the detection coil 11 protrudes to form an L shape as a whole, and the rear end of the circuit board 31 From the portion, the portion of the connection terminal portion 34 protrudes rearward from the rear end portion of the primary forming member 40.
The rear end portion of the primary forming member 40 is a small diameter portion 41 having a smaller diameter than the main body portion of the primary forming member 40, and the waterproof wall is formed to protrude from the small diameter portion 41 to the rear end over the entire circumference. 42 is provided. Further, in the lower surface side of the front end portion of the primary forming member 40, the peripheral portion of the juxtaposed portion L1 of the detection light emitting element 16 and the stability confirming light emitting element 18 (peripheral portion of the portion in contact with the secondary molded member) is provided. The waterproof wall 43 is also formed by providing a groove corresponding to the shape.

  Next, each signal line of the signal cable 32 is soldered to the power terminal 20, the ground terminal 21, and the output terminal 22 of the connection terminal portion 34. Thereafter, the L1, L2, and L3 portions are collectively subjected to secondary molding with a translucent resin. Thereby, as shown in FIG. 6, the light emitting element 16 for detection and the light emitting element 18 for stability confirmation are covered with the translucent part 51 (transparent resin) which can permeate | transmit those lights. Further, the signal cable 32 is formed integrally with the proximity sensor 10. Further, the waterproof walls 42 and 43 are molded so as to be covered with a transparent resin so that waterproofness is achieved. In this embodiment, thereafter, as shown in FIG. 1, a model number (“ABC”, “DE” in the figure) is printed on the secondary molding portion by laser light.

3. Advantages of the present embodiment (1) According to the present embodiment, the protective case 50 (case) covering the detection coil 11 (detection unit) and the light emitting elements 16 and 18 (operation display unit) is provided with the light shielding unit 52 (translucent unit). The transparent resin 51 (the range not covered with the light-transmitting resin) is formed of an alloy resin in which an amorphous plastic (polycarbonate) is mixed into a crystalline plastic (polybutylene terephthalate). Therefore, the non-crystalline plastic of the translucent part 51 (light-transmitting resin) and the non-crystalline plastic (polycarbonate) in the alloy resin are fused, so that it becomes easy to adhere at the time of molding, and the sealing of the case is improved. Can be made. Accordingly, it becomes difficult for machine oil or the like to enter from the outside, and water resistance can be further increased.

(2) According to the present embodiment, since the (transparent) polycarbonate (noncrystalline plastic) is used for both the light transmitting portion 51 and the light shielding portion 52, the polycarbonates (noncrystalline plastic) are easily fused. . Accordingly, the adhesion can be further improved.

(3) According to the present embodiment, the light shielding part 52 (the range not covered with the light transmissive resin) has a higher mixing ratio of crystalline plastic (PBT) than amorphous plastic (polycarbonate). Oil resistance and heat resistance of the light shielding part 52 can be improved.

(4) According to the present embodiment, the translucent part 51 (non-crystalline plastic covering the operation display part) includes non-crystalline plastic (polyester) having oil resistance and non-crystalline having heat resistance. An alloy resin in which a functional plastic (polycarbonate) is mixed is used. Therefore, the translucent part 51 (the area covering the operation display part) can be provided with oil resistance and heat resistance, and the oil resistance and heat resistance of the entire detection sensor can be improved.

(5) In general, the detection sensor is often used in an environment where oil resistance is required rather than heat resistance. Therefore, according to the present embodiment, polyester (oil-resistant non-crystalline plastic) used as the light-transmitting resin of the translucent part 51 (the area covering the operation display part) and (non-crystalline plastic having heat resistance) ) Is mixed with polyester in a higher mixing ratio than polycarbonate. Therefore, since oil resistance can be improved, it is suitable when used in an environment where oil resistance is required.

(6) The alloy resin that covers the operation display section is made of polyester as an oil-resistant non-crystalline plastic and polycarbonate as a heat-resistant non-crystalline plastic, while being covered with a light-transmitting resin. In a range of alloy resins, polyethylene terephthalate is used as the crystalline plastic, and polycarbonate is used as the amorphous plastic. If it does in this way, the case which has oil resistance and heat resistance can be comprised using the member (material) which has comparatively versatility.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.

(1) In the above embodiment, the proximity sensor 10 has been described as an example of the detection sensor. However, the present invention is not limited thereto, and other sensors such as a photoelectric sensor and an ultrasonic sensor may be used.
Here, in the case of a photoelectric sensor, not only the light transmitting part that transmits light from the light emitting element (operation display unit) but also light that is transmitted to the outside and received by the light receiving element. It is common to have a transparent cover (not shown) that allows the water to pass through. However, by forming the transparent cover with an alloy resin of amorphous plastics, the water resistance of the protective case can be improved.

  (2) In the above embodiment, the portion other than the portion covering the operation display portion is configured by the light shielding portion 52 made of an opaque resin that does not transmit light. However, the portion other than the portion covering the operation display portion is also transparent. Alternatively, it may be composed of a translucent alloy resin (for example, the entire case is transparent or translucent).

The top view which shows the structure of the proximity sensor which concerns on Embodiment 1 of this invention. Bottom view of proximity sensor Block diagram showing electrical configuration of proximity sensor Side view showing circuit board before molding Side cross-sectional view after primary molding of proximity sensor Side sectional view of secondary sensor after secondary molding

Explanation of symbols

10: Proximity sensor (detection sensor)
11 ... Detection coil (detection unit)
16, 18 ... Light emitting element (operation display unit)
31 ... Circuit board 50 ... Protective case
51. Light transmissive part (light transmissive resin)
52. Shading part

Claims (5)

A detection unit that performs a detection operation according to the detection state of the detected object;
An operation display unit that performs a light emission operation according to the detection operation of the detection unit;
A detection sensor comprising a case that covers the detection unit and the operation display unit,
The case is
A range covering the operation display unit is formed of a light transmissive resin,
The area not covered with the light transmissive resin is formed of a first alloy resin in which an amorphous plastic is mixed into a crystalline plastic ,
The light-transmitting resin in a range covering the operation display unit is a second alloy resin in which a plurality of types of amorphous plastics are mixed, and the second alloy resin is made of polyester and polycarbonate. Sensor. 2. The detection sensor according to claim 1, wherein the non-crystalline plastic in the first alloy resin and the non-crystalline plastic constituting the light-transmitting resin covering the operation display unit are the same. . 3. The detection sensor according to claim 1, wherein the first alloy resin has a larger mixing ratio of the crystalline plastic and the amorphous plastic than the crystalline plastic. 4. The second alloy resin, the detection sensor according to any of claims 1 to 3 towards the polyester is characterized by a high mixing ratio than the polycarbonate. The first alloy resin used in a range not covered with the light transmissive resin uses polyethylene terephthalate as a crystalline plastic and polycarbonate as an amorphous plastic. 4. The detection sensor according to any one of the above.

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