Proximity Sensor

Abstract

The present invention provides a proximity sensor capable of suppressing the drop in withstand voltage. The proximity sensor (1) comprises: a frame (10); a coil portion housed in one end of the frame (10); a fixture (20) connected to the other end of the frame (10); a substrate (30) housed in the frame (10) and the fixture (20) and equipped with a circuit electrically connected to the coil portion; a shield (45) covering a portion of the substrate (30) located on the frame (10) side; and a resin disposed in the frame (10) and the fixture (20) and covering at least a portion of the substrate (30). The shield (45) has an extension portion (452) extending into the fixture (20) and covering at least a portion of the circuit located in the fixture (20).

Description

Technical Field

[0001] The invention relates to a proximity sensor. Background Art

[0002] A proximity sensor is a sensor that detects the presence or position of a metal object as a detection object. The proximity sensor is widely used in various production equipment, industrial robots, and the like.

[0003] The proximity sensor mainly includes: a cylindrical frame, a coil portion including an iron core and a coil, and a substrate provided with a circuit electrically connected to the coil. The frame has: a shell body, which accommodates the coil portion arranged at its front end; and a clamp, which is connected to the rear side of the shell body and holds the cable connected to the substrate. The substrate carrying the circuit is located on the rear side of the coil portion inside the frame and extends to the inside of the clamp.

[0004] In the proximity sensor including the above structure, an electrostatic shield is required to protect the coil and the circuit from the influence of electromagnetic waves from the outside. In the case of a structure without an electrostatic shield, noise will overlap with the electrical signal flowing in the coil and the circuit, resulting in malfunction and other operational abnormalities of the proximity sensor.

[0005] As a document disclosing a proximity sensor provided with the electrostatic shield, there is, for example, Patent Document 1. Patent Document 1 describes an electrostatic shield for preventing the intrusion of noise from the outside, the electrostatic shield having: a first cylindrical shield portion formed in a cylindrical shape to cover the periphery of the coil portion; and a second cylindrical shield portion formed in a cylindrical shape to cover a portion of a substrate disposed in a frame body located on the shell body side.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2009-048902 Summary of the invention

[0009] Problems to be solved by the invention

[0010] In addition, in the proximity sensor, the coil part and the substrate are generally sealed with resin for the purpose of preventing moisture or oil from invading the space inside the frame from the outside. When the frame of the proximity sensor provided with an electrostatic shield as in Patent Document 1 is filled with resin, for example, the portion of the substrate not covered by the electrostatic shield (in other words, the portion of the circuit mounted on the substrate on the fixture side) is sealed with resin. However, the resin filled into the frame sometimes generates bubbles depending on its filling method or viscosity, and there is a problem of reduced withstand voltage due to the influence of the bubbles.

[0011] Therefore, an object of the present invention is to provide a proximity sensor capable of suppressing a decrease in withstand voltage.

[0012] Technical means of solving problems

[0013] A proximity sensor according to one embodiment of the present invention includes: a frame; a coil portion, which is accommodated in one end of the frame; a clamp portion, which is connected to the other end of the frame; a substrate, which is accommodated in the interior of the frame and the clamp portion and is provided with a circuit electrically connected to the coil portion; a shielding member, which covers a portion of the substrate located on the frame side; and a resin portion, which is arranged in the interior of the frame and the clamp portion and covers at least a portion of the substrate, wherein the shielding member has an extension portion, which extends into the clamp portion and covers at least a portion of the circuit located in the clamp portion.

[0014] According to this embodiment, even when bubbles are generated in the resin filled in the frame body, the shield has the extending portion that covers at least a portion of the circuit in the jig, so that a decrease in withstand voltage can be suppressed.

[0015] In the embodiment, the inner diameter of the clamp portion may be smaller than the inner diameter of the frame, the extension portion may be in a plate shape extending along the surface direction of the substrate, and the width dimension of the extension portion may be smaller than the inner diameter of the clamp portion.

[0016] According to this embodiment, even if the inner diameter of the clamp portion is smaller than the inner diameter of the frame, since the shield has a plate-shaped extension portion whose width dimension is smaller than the inner diameter of the clamp portion, the extension portion can be arranged to extend to the inside of the clamp side.

[0017] In the embodiment, the extension portion may also extend to a position covering a portion of the circuit on the clamp portion side.

[0018] According to this embodiment, since the extension portion of the shield member extends to a position covering the portion of the circuit on the clamp portion side, it is possible to further suppress a decrease in the withstand voltage due to bubbles generated in the resin.

[0019] In the embodiment, the shielding member may include: a shielding member main body portion covering a portion of the substrate located on the frame side; and an extension portion. The shielding member main body portion has a substantially elliptical cross-section whose short diameter is smaller than the inner diameter of the clamp portion, and the shielding member main body portion includes: a pair of side portions extending in a manner along the surface direction of the substrate, and a connecting portion connecting the pair of side portions. The side portion is provided on the short axis side of the substantially elliptical shape. The extension portion is a portion extending from the end of the side portion along the surface direction of the substrate to the inside of the clamp portion.

[0020] According to this embodiment, the shielding body has a roughly elliptical cross-section whose short diameter is smaller than the inner diameter of the clamp portion, and an extension portion is provided on the side portion arranged on the short axis side of the roughly elliptical shape. Therefore, even in a structure where the inner diameter of the clamp is smaller than the inner diameter of the frame, the extension portion can be easily extended to the interior of the clamp.

[0021] Effects of the Invention

[0022] According to the present invention, it is possible to provide a proximity sensor capable of suppressing a decrease in withstand voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is an exploded perspective view showing the sensor according to this embodiment.

[0024] Figure 2 yes Figure 1 A cross-sectional view taken along line II-II of the sensor in an assembled state is shown.

[0025] Figure 3 Yes means Figure 1 The diagram shows the internal structure of the sensor when the sensor is assembled.

[0026] Figure 4 Yes means Figure 1 A perspective view of the structure of the shielding element in the sensor is shown.

[0027] Figure 5 (A) means Figure 3 A cross-sectional view of section AA is shown. Figure 5 (B) means Figure 3 A cross-sectional view of section BB is shown.

[0028] [Explanation of Symbols]

[0029] 10: Frame

[0030] 20: Fixture

[0031] 25: O-ring

[0032] 30: Substrate

[0033] 40: Inspection Department

[0034] 41: Iron core

[0035] 42: Coil

[0036] 45: Shielding

[0037] 452: Extension

[0038] R: Sealing resin DETAILED DESCRIPTION

[0039] The preferred embodiment of the present invention will be described with reference to the accompanying drawings. In each of the drawings, the parts with the same reference numerals have the same or identical structure.

[0040] Reference Figure 1 and Figure 2 , the internal structure of the sensor 1 is described. Figure 1 It is an exploded perspective view of the sensor 1 according to the embodiment of the present invention. Figure 2 yes Figure 1 The sensor 1 is shown in a cross-sectional view taken along line II-II in an assembled state.

[0041] The sensor 1 of this embodiment is a proximity sensor capable of detecting the approach of a detection object in a non-contact manner, and includes: a frame 10, a fixture 20, an O-ring 25, a substrate 30, a cable bare wire 34, a cable 35, a ring part 36, a detection unit 40 and a shielding member 45. The frame 10 is formed in a cylindrical shape, and electronic components such as the substrate 30 are accommodated inside. The frame 10 has an opening 11 at one end, and electronic components such as the substrate 30 are inserted from the opening 11. The frame 10 can be formed of metal or resin. Although the outer shape of the sensor 1 is cylindrical, it can also be a prism shape in which the outer periphery of the frame 10 or the fixture 20 is polygonal.

[0042] The end of the clamp 20 is connected to the opening 11 of the frame 10, and the clamp 20 protects electronic components such as the substrate 30 housed in the frame 10. Figure 1 As shown by the arrow, the direction from the fixture 20 toward the frame 10 along the axial direction of the sensor 1 is set as the front, and the direction from the frame 10 toward the fixture 20 is set as the rear. Figure 2 As shown, the front portion of the clamp 20 is inserted into the frame 10 from the opening 11. Most of the substrate 30 is accommodated in the frame 10, but the rear area of ​​the substrate 30 is accommodated in the clamp 20. In addition, the clamp 20 accommodates the cable bare wire 34, the ring part 36 and a part of the cable 35.

[0043] The clamp 20 is cylindrical in shape. The clamp 20 has a recess 24, and an O-ring 25 is installed in the recess 24. Figure 2As shown, the O-ring 25 is located inside the frame 10 when the sensor 1 is assembled, and seals the gap between the inner wall of the frame 10 and the outer wall of the fixture 20 .

[0044] The clamp 20 may be formed of resin, metal or the like, but is preferably formed of a transparent material that transmits visible light so that the indicator light 32 located inside the sensor 1 can be seen from the outside.

[0045] The substrate 30 is a substrate on which a control circuit (not shown) for controlling the detection unit 40 and a current supply circuit (not shown) for supplying current to the detection unit 40 are mounted, and a portion of the substrate is accommodated in the housing 10. Figure 2 As shown, a detection unit 40 is installed at the end of the front side of the substrate 30. The detection unit 40 detects the presence or absence of a detection object in a non-contact manner. The detection unit 40 includes: an iron core 41 that accommodates a coil 42 and a coil 42 wound into a ring shape. On the other hand, a connection plate (land) 31 is provided at the end of the rear side of the substrate 30, so as to be electrically connected to the cable bare wire 34. Here, a detection method of a detection object using the sensor 1 is described. First, an excitation current is supplied to the coil 42 from a current supply circuit mounted on the substrate 30. The coil 42 generates a magnetic field based on the supplied excitation current. In this state, if a detection object such as metal approaches the coil 42, an eddy current will be generated inside the detection object according to the law of electromagnetic induction. Since the eddy current generates a magnetic field, the magnetic flux passing through the coil 42 and even the impedance of the coil 42 will change. The control circuit connected to the detection unit 40 measures the change in the impedance of the coil 42 to detect the presence or absence of the detection object.

[0046] The substrate 30 is provided with an indicator light 32 for displaying the operating state of the sensor 1. The indicator light 32 may be, for example, a light emitting diode (LED), etc. In the present embodiment, the indicator light 32 is lit when the power of the sensor 1 is turned on or when the sensor 1 detects a detection object.

[0047] The cable 35 is formed by applying a protective coating to a plurality of bare cable wires 34. The bare cable wires 34 are electrically connected to the connection pads 31 of the substrate 30. The bare cable wires 34 can supply power from an external power source to the circuit mounted on the substrate 30. In addition, the bare cable wires 34 can transmit output signals from the control circuit mounted on the substrate 30 to external devices such as amplifiers.

[0048] The ring part 36 is provided on the outer periphery of the cable 35 to prevent damage to the cable 35. Specifically, the ring part 36 is formed by injection molding or the like at a position to cover the end of the cable 35 to protect the coating. The ring part 36 is in close contact with the sealing resin filled in the frame 10, thereby fixing the cable 35 to the clamp 20.

[0049] A sealing ring 38 is provided between the cable 35 and the fixture 20 and in a region further back than the annular part 36 so as to surround the cable 35. The sealing ring 38 seals the gap between the inner wall of the fixture 20 and the outer periphery of the cable 35. The sealing ring 38 prevents liquid or dust from penetrating from the outside of the sensor 1. In addition, the sealing ring 38 prevents the sealing resin R ( Figure 2 and Figure 3 ) leaks to the outside.

[0050] The shield 45 removes noise from the outside. The shield 45 is provided so as to surround the detection unit 40 and a part of the substrate 30 to prevent noise from reaching the detection unit 40 and the substrate 30. The shield 45 may be formed of, for example, a metal film or a laminated member of copper foil and polyimide resin.

[0051] The structure of the portion of the shield 45 provided so as to surround a portion of the substrate 30 will be described. Hereinafter, the portion of the shield 45 provided so as to surround a portion of the substrate 30 will be referred to as a shield main body 451 . Figure 4 It is a perspective view showing the structure of the shield main body 451 and the extension portion 452 . Figure 5 (A) means Figure 3 A cross-sectional view of section AA is shown. Figure 5 (B) means Figure 3 A cross-sectional view of section BB is shown.

[0052] like Figure 4 and Figure 5 As shown in (A), the shield body 451 includes a pair of side surfaces 451 a and a connecting surface 451 b connecting the pair of side surfaces 451 a in an arc shape, and has a substantially elliptical shape in cross-sectional view.

[0053] The pair of side portions 451a are substantially flat in shape in this embodiment. The pair of side portions 451a are arranged to extend along the surface direction of the substrate 30 in the assembled state of the sensor. A pair of extension portions 452 are connected to one end side of the pair of side portions 451a (the portion of the side portions 451a on the side of the clamp 20).

[0054] The extension portion 452 is a portion that protrudes from the end E of the shield body portion 451 toward the clamp 20 side, and is provided to extend along the length direction of the pair of side portions 451a. Figure 2 and Figure 3As shown, the extension portion 452 extends to the inside of the fixture 20 and covers at least a portion of the circuit located on the fixture 20 side of the circuit mounted on the substrate 30. In this way, the shielding member 45 has the extension portion 452 that covers at least a portion of the circuit located inside the fixture 20, so even if bubbles are generated in the resin filled inside, the withstand voltage can be suppressed from decreasing due to the bubbles generated in the resin. Preferably, the extension portion 452 extends along the surface direction of the substrate 30 to a position covering the circuit located on the fixture 20 side of the circuit mounted on the substrate 30. For example, the extension portion 452 can extend along the surface direction of the substrate 30 to extend to the vicinity of the indicator light 32 mounted on the substrate 30 (the portion that does not abut against the indicator light 32).

[0055] In the present embodiment, the surface side of the portion of the substrate 30 located on the jig 20 side is protected by the extension portion 452, and the side side of the portion of the substrate 30 located on the jig 20 side (the portion located on the outer peripheral side of the jig 20) is protected by the sealing resin R ( Figure 3 ) protection. The presence of the extension portion 452 of the shield 45 on the circuit components mounted on the surface side of the portion of the substrate 30 located on the jig 20 side can improve noise resistance.

[0056] In the sensor 1 of the present embodiment, the inner diameter D2 ( Figure 3 ) is smaller than the inner diameter D1 of the frame 10. When the shield 45 is viewed from a direction perpendicular to the surface of the substrate 30 (see Figure 3 ), the width dimension D4 of the extension portion 452 ( Figure 3 and Figure 5 (A)) is smaller than the width dimension D3 of the shield body 451 ( Figure 3 and Figure 5 (B)) and is smaller than the inner diameter D2 of the fixture 20. In the present embodiment, when the shield 45 is viewed from a direction perpendicular to the surface of the substrate 30 (refer to Figure 3 ), the extension portion 452 is cut off on both sides in the width direction relative to the shield body 451, thereby making the width dimension D4 of the extension portion 452 smaller than the width dimension D3 of the shield body 451.

[0057] As described above, the shielding member body 451 has a substantially elliptical cross section. Figure 5 As shown in (B), the shield body 451 (side surface 451a and connecting surface 451b) has a substantially elliptical cross section with a major axis AX1 along the width direction of the substrate 30 and a minor axis AX2 in a direction perpendicular to the surface of the substrate 30. The minor diameter D5 ( Figure 5(B)) is smaller than the inner diameter D2 of the jig 20, and an extension portion 452 ( Figure 5 (A)). Thus, in the present embodiment, the shield body 451 is set to be substantially elliptical, and the extension 452 is provided on the side of the minor axis AX2 of the substantially elliptical shape, and as described above, the dimension D4 of the extension 452 in the width direction is made smaller than the inner diameter D2 of the fixture 20. By providing the extension 452 in this way, even if the inner diameter D2 of the fixture 20 is smaller than the inner diameter D1 of the frame 10, the extension 452 connected to the minor axis AX2 side of the shield body 451 (the side of the side portion 451a of the shield body 451) which is substantially elliptical when viewed in cross section can be arranged to extend to the inside of the fixture 20 along the surface direction of the substrate 30.

[0058] In the above-described embodiment, the extension portion 452 is a flat plate extending along the surface direction of the substrate 30, but the present invention is not limited thereto. That is, the extension portion 452 can be deformed into various other shapes as long as it extends into the fixture 20 and covers at least a portion of the circuit in the fixture 20.

[0059] The above-described embodiments are intended to make the present invention easy to understand and are not intended to limitatively explain the present invention. The flowcharts, sequences, elements included in the embodiments and their configurations, materials, conditions, shapes, and sizes described in the embodiments are not limited to the illustrated contents but may be appropriately changed. In addition, the structures shown in different embodiments may be partially replaced or combined with each other.

[0060] [Note 1]

[0061] A proximity sensor 1, comprising:

[0062] Frame 10;

[0063] The coil portion is accommodated in one end portion of the frame 10;

[0064] A clamp 20 connected to the other end of the frame 10;

[0065] The substrate 30 is accommodated in the frame 10 and the fixture 20 and is equipped with a circuit electrically connected to the coil part;

[0066] a shielding member 45 covering a portion of the substrate 30 located on the frame body 10 side; and

[0067] The sealing resin R is disposed inside the frame 10 and the fixture 20 and covers at least a portion of the substrate 30.

[0068] The shielding member 45 has an extending portion 452 , and the extending portion 452 extends into the fixture 20 and covers at least a portion of the circuit located in the fixture 20 .

Claims

1. A proximity sensor, characterized in that: include: Frame; A coil portion, housed in one end portion of the frame; A clamp portion connected to the other end of the frame; a substrate, which is accommodated in the frame and the fixture and carries a circuit electrically connected to the coil; a shielding member covering a portion of the substrate located on the frame side; and a resin portion, which is disposed inside the frame and the clamp portion and covers at least a portion of the substrate, The shielding member has an extension portion, the extension portion extends into the fixture portion and covers at least a portion of the circuit located in the fixture portion. The shielding member includes: a shielding member main body portion covering a portion of the substrate located on the frame side; and the extending portion, The shielding member main body has an elliptical cross section whose short diameter is smaller than the inner diameter of the clamp portion, and The shield body includes a pair of side surfaces extending along a surface direction of the substrate and a connection portion connecting the pair of side surfaces. The side surface portion is disposed on the short axis side of the ellipse, The extending portion is a portion extending from an end portion of the side surface portion along a surface direction of the substrate to an interior of the clamp portion.

2. The proximity sensor according to claim 1, characterized in that: The inner diameter of the clamp portion is smaller than the inner diameter of the frame body, The extension portion has a plate shape extending along a surface direction of the substrate, and a dimension in a width direction of the extension portion is smaller than an inner diameter of the clamp portion.

3. The proximity sensor according to claim 1 or 2, characterized in that: The extension portion extends to a position covering a portion of the circuit on the clamp portion side.

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