JP2017107760A - Proximity sensor - Google Patents

Abstract

Provided is a proximity sensor that is provided with a transmission coil and a reception coil separately, and that has greatly improved temperature characteristics. A proximity sensor (1) includes an oscillation waveform generation circuit (35), at least one transmission pattern coil (31) connected to the waveform generation circuit (35) and formed on at least one layer of a substrate (30), and formed on at least one layer of the substrate (30). The transmission pattern coil 31 is connected to the at least one reception pattern coil 32, at least one shield pattern 33 formed between the coils 31 and 32, the transmission pattern coil 31 and the reception pattern coil 32. And a detection circuit 37 for detecting a detected object based on the voltage or current value of the reception pattern coil 32 and the voltage or current value of the reception pattern coil 32. [Selection] Figure 1

Description

  The present invention relates to a proximity sensor (also referred to as a proximity switch) that determines the approach of a metal object by the action of an alternating magnetic field, and more particularly to a proximity sensor that includes a transmission coil and a reception coil separately.

  Conventionally, proximity sensors, proximity switches, and the like that determine the approach of a metal object by the action of an alternating magnetic field have been proposed (see, for example, Patent Documents 1 to 5).

  In the non-contact detection apparatus disclosed in Patent Document 1, a shield member is provided between a first detection coil that exclusively handles object detection and a second detection coil that exclusively detects external electromagnetic waves. However, the first detection coil and the second detection coil are both detection coils (reception coils), and either one is not a transmission coil.

  In the proximity switch disclosed in Patent Document 2, a shield conductor layer is provided on the back side of the detection coil provided on the substrate, and a slit is formed in the shield conductor layer.

  In the proximity switch disclosed in Patent Document 3, a detection coil is formed by a plurality of coil patterns on a substrate that can be folded in a bellows shape, and a shield pattern so that a circuit portion on the substrate is not electrically affected. Is provided.

  In the semiconductor device disclosed in Patent Document 4, a spiral metal wiring (pattern coil) disposed on a substrate over a single layer or multiple layers is used as a detection coil of a proximity switch.

  In the proximity sensor disclosed in Patent Document 5, an excitation coil (transmission coil) and a detection coil (reception coil) are separately provided. Since the excitation coil and the detection coil are magnetically coupled, a direct magnetic field from the excitation coil affects the detection coil. However, these excitation coils and detection coils are not pattern coils formed by drawing a pattern on the substrate, and there is no description regarding the shield between the excitation coil and the detection coil.

JP 2014-086954 A Japanese Patent Laid-Open No. 05-105808 Japanese Patent Laid-Open No. 62-190628 Japanese Patent Application Laid-Open No. 07-037476 Japanese Patent Laid-Open No. 02-173592

  In the case of a proximity sensor having a transmission coil and a reception coil separately, capacitive coupling (electrostatic coupling) occurs between the two coils. This capacitive coupling is easily influenced by temperature, and the received signal fluctuates greatly regardless of the presence or absence of the detection target. The fluctuation of the received signal due to the temperature cannot be separated from the original detection signal. Therefore, the detection performance of the proximity sensor greatly varies depending on the temperature.

  In view of such a problem of the prior art, an object of the present invention is to provide a proximity sensor having greatly improved temperature characteristics while separately including a transmission coil and a reception coil.

  To achieve the above object, a proximity sensor according to the present invention includes an oscillation circuit, at least one transmission pattern coil connected to the oscillation circuit and formed on at least one layer of the substrate, and at least one of the substrate. At least one reception pattern coil formed in a layer, at least one shield pattern formed between the transmission pattern coil and the reception pattern coil of the substrate, the transmission pattern coil, and the reception A detection circuit that is connected to the pattern coil for detection and detects a detected object based on the voltage or current value of the transmission pattern coil and the voltage or current value of the reception pattern coil. .

  Here, the transmission pattern coil and the reception pattern coil are one or more coils formed by drawing a pattern on at least one layer of a single layer substrate or a multilayer substrate. The shield pattern is also formed by drawing a pattern in the same manner, but it is preferable that the shield pattern is formed so as to have a dividing portion (for example, a slit) that divides the eddy current path.

  According to the proximity sensor having such a configuration, since the pattern coil is used as the transmission pattern coil and the reception pattern coil, a shield pattern can be easily formed between the two coils. Thereby, since the capacitive coupling between the transmission coil and the reception coil is suppressed by the shield pattern, the temperature characteristic of the detection performance is greatly improved.

  In the proximity sensor of the present invention, the substrate is a multilayer substrate, and for each layer of the multilayer substrate, the reception pattern coil forming layer in which the reception pattern coil is formed and the transmission pattern coil are formed. It does not overlap with the transmission pattern coil formation layer, and neither the transmission pattern coil nor the reception pattern coil is formed between the transmission pattern coil layer and the reception pattern coil layer. One layer exists, and the shield pattern may be formed in a layer between the reception pattern coil formation layer and the transmission pattern coil formation layer. In other words, the transmission pattern coil and the reception pattern coil are formed in separate layers, and the transmission pattern coil and the reception pattern coil do not exist in the same layer.

  Alternatively, in the proximity sensor according to the present invention, the substrate is a single layer substrate or a multilayer substrate, and the transmission pattern coil is formed on one of the outer periphery and the center on at least one layer of the substrate, and Alternatively, the reception pattern coil may be formed on the other side closer to the center, and further, the shield pattern may be formed between the transmission pattern coil and the reception pattern coil.

  Here, when there are a plurality of the transmission pattern coils or the reception pattern coils, the transmission pattern coils or the reception pattern coils operate as one transmission coil or one reception coil. As such, they may be electrically connected.

  Alternatively, in the proximity sensor of the present invention, the substrate is a multilayer substrate, and the shield pattern, the transmission pattern coil, and the reception pattern coil are formed on each of a plurality of layers of the substrate, and are formed on each layer. The transmission pattern coils and the reception coil patterns may be electrically connected to operate as one transmission coil and one reception coil, respectively.

  According to the proximity sensor of the present invention, since the capacitive coupling between the transmission coil and the reception coil is suppressed by the shield pattern, the temperature characteristic of the detection performance is greatly improved.

It is a schematic block diagram explaining the principle of operation of proximity sensor 1 concerning a 1st embodiment of the present invention. 1 is an example of a cross-sectional view illustrating a schematic configuration of a distal end portion of a proximity sensor 1. FIG. (A) is a schematic sectional drawing of the pattern coil board | substrate 30 of the proximity sensor 1, (b) is a schematic perspective view of the pattern coil board | substrate 30. FIG. (A) is a schematic plan view of the shield pattern 33 of the pattern coil board | substrate 30, (b) is a schematic plan view of the shield pattern 33X which is the modification. (A) is a schematic sectional drawing of the pattern coil board | substrate 30A of the proximity sensor which concerns on 2nd Embodiment, (b) is a perspective view which shows schematic structure of one layer of them, (c) is mutually connected It is a perspective view which shows schematic structure of 2 layers.

  Hereinafter, some embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
1.1 Operation Principle of Proximity Sensor 1 FIG. 1 is a schematic block diagram illustrating the operation principle of the proximity sensor 1 according to the first embodiment of the present invention.

  As shown in FIG. 1, the proximity sensor 1 includes an oscillation waveform generation circuit 35 that generates an oscillation waveform, a constant current circuit 36 that outputs an excitation current according to an output signal from the oscillation waveform generation circuit 35, and a constant current circuit 36. A transmitting pattern coil 31 that generates an exciting magnetic flux Φ1 with respect to the metal workpiece W by an exciting current from the current circuit 36, and a receiving pattern that receives an eddy current magnetic flux Φ2 due to the eddy current generated in the metallic workpiece W by the exciting magnetic flux Φ1. The coil 32, the shield pattern 33 disposed between the transmission pattern coil 31 and the reception pattern coil 32, the voltage or current value of the transmission pattern coil 31, and the voltage or current value of the reception pattern coil 32 And a determination circuit for determining the proximity of the metal workpiece W based on the detection result of the detection circuit 37. It is equipped with a 38.

  Here, the transmission pattern coil 31 and the reception pattern coil 32 are one or more coils formed by drawing a conductor such as copper as a pattern (wiring) on at least one layer of a single-layer substrate or a multilayer substrate. It is. When coil patterns are formed on a plurality of layers of the multilayer substrate, the coil patterns of each layer are electrically connected by through holes or vias to form one coil. The transmission pattern coil 31 and the reception pattern coil 32 may be formed on a single layer substrate or in the same layer of a multilayer substrate. In the multilayer substrate, the layer for forming the transmission pattern coil 31 and the layer for forming the reception pattern coil 32 are not overlapped. Moreover, the coil patterns of each layer are not limited to through holes or vias, but may be anything as long as the coil patterns of each layer are electrically connected to operate as one coil. You may connect with a lead wire.

  The shield pattern 33 is also formed by drawing a pattern on at least one layer of a single layer substrate or a multilayer substrate.

  As a specific example of the detection circuit 37 and the determination circuit 38, a combination of the phase shift circuit 4 and the synchronous detection circuit 5 described in Patent Document 5 can be used, but is not limited thereto.

1.2 Schematic Configuration of Proximity Sensor 1 FIG. 2 is an example of a cross-sectional view illustrating a schematic configuration of a tip portion of the proximity sensor 1.

  As shown in FIG. 2, the proximity sensor 1 includes a cylindrical metal casing 10, a multi-layer pattern coil substrate 30 disposed so as to be fitted to the tip of the metal casing 10, and an interior of the metal casing 10. And a circuit board 20 connected to the pattern coil board 30.

  The transmission pattern coil 31, the reception pattern coil 32, and the shield pattern 33 described above are formed in the pattern coil substrate 30. The detailed configuration of the pattern coil substrate 30 will be described later.

  On the other hand, various circuit components 21 including the above-described oscillation waveform generation circuit 35, constant current circuit 36, detection circuit 37 and determination circuit 38 are mounted on both surfaces of the circuit board 20. However, if possible, it may be mounted only on one side of the circuit board 20 or some components may be arranged outside the metal housing 10 (however, electrically connected to the circuit board 20). deep).

1.3 Schematic Configuration of Pattern Coil Substrate 30 FIG. 3A is a schematic cross-sectional view of the pattern coil substrate 30 of the proximity sensor 1, and FIG. 3B is a schematic perspective view of the pattern coil substrate 30. 4A is a schematic plan view of the shield pattern 33 of the pattern coil substrate 30, and FIG. 4B is a schematic plan view of a shield pattern 33X which is a modified example thereof.

  As shown in FIGS. 3A and 3B, the disc-shaped pattern coil substrate 30 is a multilayer substrate (three-layer substrate) composed of three layers 30a to 30c. However, it is not limited to a three-layer substrate. Further, the pattern coil substrate 30 is not limited to a disc shape, and may be a rectangle, for example.

  A pattern coil 31 for transmission is formed on the upper layer 30a of the pattern coil substrate 30, and a pattern coil 32 for reception is similarly formed on the lower layer 30c. In the intermediate layer 30 b of the pattern coil substrate 30, a shield pattern 33 is formed between the entire pattern of the transmission pattern coil 31 and the entire pattern of the reception pattern coil 32.

  However, the configuration is not limited to this, and the transmission pattern coil 31 and the reception pattern coil 32 may be arranged upside down. That is, the reception pattern coil 32 may be formed on the upper layer 30a of the pattern coil substrate 30, and the transmission pattern coil 31 may be formed on the lower layer 30c. If the pattern coil substrate 30 is a multilayer substrate having four or more layers, the transmission pattern coil 31 may be formed in two or more layers, and the pattern coils of each layer may be electrically connected by through holes or vias. . Alternatively, the receiving pattern coil 32 may be formed in two or more layers, and the pattern coils of each layer may be electrically connected by through holes or vias.

  As shown in FIG. 4A, the shield pattern 33 has a substantially donut shape in plan view. In order to suppress the generation of eddy currents as much as possible, it is preferable that the eddy current path be cut. For example, it is good also as a shape where the slit 34 exists as a parting part which parts such a path. However, the slit 34 is not limited to such a shape, and the width of the slit 34 may be increased as appropriate. Moreover, it is good also as a shape where a parting part, a slit, a notch part, etc. exist in two or more places.

  As a modified example of the shield pattern 33, as shown in FIG. 4B, a plurality of thin concentric annular patterns that enter between each pattern of the transmission pattern coil 31 and each pattern of the reception pattern coil 32, respectively. A shield pattern 33X made of can also be considered. Similarly to the shield pattern 33, for example, a slit 34X may be provided in order to form a shape that divides the eddy current path.

  According to the proximity sensor 1 according to the first embodiment described above, the multilayer pattern coil substrate 30 is used, and the transmission coil, the reception coil, and the shield layer are formed as patterns on the substrate. The shield pattern 33 or the shield pattern 33X can be easily formed between the transmission pattern coil 31 and the reception pattern coil 32 in the manufacturing process. Thereby, since the capacitive coupling between both coils is suppressed by the shield pattern 33 or the shield pattern 33X, the temperature characteristic of the detection performance is greatly improved.

Second Embodiment
The pattern coil substrate 30 of the proximity sensor 1 according to the first embodiment described above is replaced with a pattern coil substrate 30A having a different configuration as the second embodiment. Hereinafter, differences from the first embodiment will be mainly described. .

2.1 Schematic Configuration of Pattern Coil Substrate 30A FIG. 5A is a schematic cross-sectional view of the pattern coil substrate 30A of the proximity sensor according to the second embodiment, and FIG. 5B shows a schematic configuration of one of them. FIG. 5C is a perspective view showing a schematic configuration of two layers connected to each other.

  As shown in FIGS. 5A to 5C, the disc-shaped pattern coil substrate 30A is a multilayer substrate (two-layer substrate) composed of two layers 30Aa and 30Ac. However, it is not limited to a two-layer substrate. Reference numeral 30Ab denotes a resin provided between the upper layer 30Aa and the lower layer 30Ac of the pattern coil substrate 30A.

  In the upper layer 30Aa of the pattern coil substrate 30A, a transmission pattern coil 31A is formed near the outer periphery, and a reception pattern coil 32A is formed near the center of the same layer 30Aa. In the same layer 30Aa, a shield pattern 33A is formed between the innermost pattern of the transmitting pattern coil 31A and the outermost pattern of the receiving pattern coil 32A.

  Similarly, in the lower layer 30Ac of the pattern coil substrate 30A, a transmission pattern coil 31A is formed near the outer periphery, and a reception pattern coil 32A is formed near the center of the same layer 30Ac. In the same layer 30Ac, a shield pattern 33A is formed between the innermost peripheral pattern of the transmitting pattern coil 31A and the outermost peripheral pattern of the receiving pattern coil 32A.

  Further, as shown in FIG. 5C, the transmission pattern coils 31A, the reception pattern coils 32A, and the shield patterns 33A of the upper layer 30Aa and the lower layer 30Ac are electrically connected to each other by through holes or vias. Connected. Thereby, the lengths of the transmission and reception coils can be increased.

  However, the present invention is not limited to this configuration, and the reception pattern coil 32A may be formed near the outer periphery, and the transmission pattern coil 31A may be formed near the center.

  According to the proximity sensor according to the second embodiment described above, the multilayer pattern coil substrate 30A is used, and the transmission coil, the reception coil, and the shield are formed as patterns on the substrate. Thus, the shield pattern 33A can be easily formed between the transmission pattern coil 31A and the reception pattern coil 32A. Thereby, since the capacitive coupling between both coils is suppressed by the shield pattern 33A, the temperature characteristic of the detection performance is greatly improved.

2.2 Modification of Pattern Coil Substrate 30A In addition to using a single layer substrate instead of the pattern coil substrate 30A, the transmitting pattern coil 31A is formed near the outer periphery (or from the center) on the single layer substrate, The reception pattern coil 32A may be formed closer to the center (or from the outer periphery), and the shield pattern 33A may be further formed therebetween.

  Further, the transmission pattern coil, the reception pattern coil, and the shield pattern may be formed only on one surface of the pattern coil substrate, or may be formed on both surfaces of the substrate. When formed on both surfaces, the transmitting pattern coils and the receiving pattern coils may be electrically connected to each other by a through hole or a wiring.

  Further, only a transmission pattern coil is formed on one layer of the multilayer substrate, and a transmission pattern coil, a reception pattern coil, and a shield pattern as shown in the second embodiment are formed on the other layer. The pattern coils may be electrically connected.

  It should be noted that the present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiments and examples are merely examples in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Proximity sensor 10 Metal housing 20 Circuit board 21 Circuit components 30 and 30A
Pattern coil substrate 31, 31A
Transmitting pattern coils 32, 32A
Reception pattern coils 33, 33A, 33X
Shield pattern 34, 34X
Slit 35 Oscillation waveform generation circuit 36 Constant current circuit 37 Detection circuit 38 Determination circuit

Claims (6)

An oscillation circuit;
At least one transmitting pattern coil connected to the oscillation circuit and formed in at least one layer of the substrate;
At least one receiving pattern coil formed on at least one layer of the substrate;
At least one shield pattern formed between the transmitting pattern coil and the receiving pattern coil of the substrate;
A detection circuit that is connected to the transmission pattern coil and the reception pattern coil and detects a detected object based on the voltage or current value of the transmission pattern coil and the voltage or current value of the reception pattern coil A proximity sensor characterized by comprising: The proximity sensor according to claim 1,
The substrate is a multilayer substrate;
For each layer of the multilayer substrate, the receiving pattern coil forming layer in which the receiving pattern coil is formed and the transmitting pattern coil forming layer in which the transmitting pattern coil is formed do not overlap,
Between the transmission pattern coil layer and the reception pattern coil layer, there is at least one layer in which neither the transmission pattern coil nor the reception pattern coil is formed,
The proximity sensor, wherein the shield pattern is formed in a layer between the receiving pattern coil forming layer and the transmitting pattern coil forming layer. The proximity sensor according to claim 1,
The substrate is a single layer substrate or a multilayer substrate;
In at least one layer of the substrate, the transmission pattern coil is formed on one of the outer periphery and the center, the reception pattern coil is formed on the other of the outer periphery and the center, and the transmission pattern is further formed. A proximity sensor, wherein the shield pattern is formed between a coil and the receiving pattern coil. The proximity sensor according to claim 3,
When there are a plurality of the transmission pattern coils or the reception pattern coils, the transmission pattern coils or the reception pattern coils are electrically operated so as to operate as one transmission coil or one reception coil. Proximity sensor, characterized in that they are connected together. The proximity sensor according to claim 4,
The substrate is a multilayer substrate;
The shield pattern, the transmission pattern coil and the reception pattern coil are respectively formed on a plurality of layers of the substrate,
The proximity sensor, wherein the transmitting pattern coils and the receiving coil patterns formed on each layer are electrically connected so as to operate as one transmitting coil and one receiving coil, respectively. . The proximity sensor according to any one of claims 1 to 5,
2. The proximity sensor according to claim 1, wherein the shield pattern is formed so as to have a dividing portion that divides an eddy current path.

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