JP2017161494A - Proximity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a smaller proximity sensor that can detect a detection object while suppressing the influence from a peripheral object except the detection object.SOLUTION: A proximity sensor includes: a substrate; a first shield electrode provided on a surface of the substrate; a first detection electrode which is provided on the surface of the substrate around the first shield electrode, insulated from the first shield electrode, and has an outer periphery with a polygonal shape; a driving unit in which the first shield electrode and the first detection electrode are connected, to which power is supplied, and which applies voltage so that the first shield electrode and the first detection electrode have the same potential; and a detection unit that detects the change in electrostatic capacitance in the first detection electrode.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a proximity sensor that detects the approach of an object such as a person.

  Patent Document 1 discloses a proximity sensor that detects an object based on a change in capacitance. This proximity sensor can detect a detection target by using two detection electrodes and a ground electrode while reducing the influence of a peripheral object that is not the detection target.

International Publication No. 2004/059343

  The present disclosure provides a proximity sensor that can detect a detection target while reducing the influence of a peripheral object that is not the detection target, and can be downsized.

  A proximity sensor according to an aspect of the present disclosure includes a substrate, a first shield electrode provided on a surface of the substrate, and a first detection electrode provided around the first shield electrode on the surface of the substrate, A drive unit that is insulated from the shield electrode and has a polygonal outer periphery; the first shield electrode and the first detection electrode are connected to each other; and the power is supplied to the drive unit. A drive unit that applies a voltage so that one detection electrode has the same potential, and a detection unit that detects a change in capacitance in the first detection electrode.

  A proximity sensor according to another aspect of the present disclosure includes a substrate, a first shield electrode provided on the surface of the substrate, and a first detection electrode provided around the first shield electrode on the surface of the substrate. A first detection electrode insulated from the first shield electrode, and a second detection electrode provided inside the first detection electrode on the surface of the substrate, wherein the first shield electrode and the first detection electrode are A drive unit to which the insulated second detection electrode, the first shield electrode, the first detection electrode, and the second detection electrode are connected and supplied with power, the first shield electrode, the first detection electrode, and the second A drive unit that applies a voltage so that the detection electrodes have the same potential; and a detection unit that detects a change in capacitance in the first detection electrode and the second detection electrode.

  The proximity sensor according to the present disclosure can detect a detection target while reducing the influence of a peripheral object that is not the detection target, and can be downsized.

FIG. 1 is a block diagram of a proximity sensor according to the first embodiment. FIG. 2 is an external view of a sensor unit of the proximity sensor according to the first embodiment. FIG. 3 is a schematic diagram illustrating an example of the configuration of the detection unit of the proximity sensor in FIG. 1. FIG. 4 is a calculation model diagram of the sensor unit of Example 1 of the first embodiment. FIG. 5 is a calculation model diagram of the sensor unit of the first comparative example of the first embodiment. FIG. 6 is a diagram showing the calculation results of the capacitances of the sensor units of Example 1 and Comparative Example 1. FIG. 7 is a calculation model diagram of the sensor unit of Example 2 of the first embodiment. FIG. 8 is a comparative calculation model diagram of the sensor unit of the second comparative example of the second embodiment. FIG. 9 is a diagram showing the calculation results of the capacitances of the sensor units of Example 2 and Comparative Example 2. FIG. 10 is a schematic diagram of a sensor unit of the proximity sensor according to the second embodiment. FIG. 11 is a schematic diagram illustrating an example of a configuration of a detection unit of the proximity sensor according to the second embodiment. FIG. 12 is a schematic diagram of a sensor unit of the proximity sensor according to the third embodiment. FIG. 13 is a schematic diagram illustrating an example of a configuration of a detection unit of the proximity sensor according to the third embodiment. FIG. 14 is a schematic diagram illustrating an application example of the proximity sensor of the present disclosure.

  The inventors of the present invention relate to the technology described in the section of “Background Art”, a proximity sensor that can detect a detection target while reducing the influence of a peripheral object that is not the detection target, and can be downsized. I found it like this.

  A proximity sensor according to an aspect of the present disclosure includes a substrate, a first shield electrode provided on a surface of the substrate, and a first detection electrode provided around the first shield electrode on the surface of the substrate, A drive unit that is insulated from the shield electrode and has a polygonal outer periphery; the first shield electrode and the first detection electrode are connected to each other; and the power is supplied to the drive unit. A drive unit that applies a voltage so that one detection electrode has the same potential, and a detection unit that detects a change in capacitance in the first detection electrode.

  In the above-described configuration, since the first detection electrode is disposed around the first shield electrode, even if the overall size of the first detection electrode and the first shield electrode is small, the detected object and the first detection electrode It is possible to ensure a predetermined capacitance between the two. Thereby, a proximity sensor can be reduced in size easily. Furthermore, by arranging the first detection electrode and the first shield electrode, even if the entire size of the first detection electrode and the first shield electrode is small, the sensitivity to the detected object is increased, and the attached matter such as water droplets. The sensitivity to can be reduced. Therefore, the proximity sensor can detect the approach of the detected object while preventing erroneous detection, and can be downsized.

  A proximity sensor according to another aspect of the present disclosure includes a substrate, a first shield electrode provided on the surface of the substrate, and a first detection electrode provided around the first shield electrode on the surface of the substrate. A first detection electrode insulated from the first shield electrode, and a second detection electrode provided inside the first detection electrode on the surface of the substrate, wherein the first shield electrode and the first detection electrode are A drive unit to which the insulated second detection electrode, the first shield electrode, the first detection electrode, and the second detection electrode are connected and supplied with power, the first shield electrode, the first detection electrode, and the second A drive unit that applies a voltage so that the detection electrodes have the same potential; and a detection unit that detects a change in capacitance in the first detection electrode and the second detection electrode.

  In the above-described configuration, the first and second detection electrodes and the first shield electrode are arranged and the first detection electrode is arranged around the first shield electrode. The approach of the detection body can be detected, and the size can be reduced. Furthermore, by using the difference in voltage change between the first detection electrode and the second detection electrode, it is possible to reduce the influence on the detection accuracy of the proximity sensor due to environmental noise caused by electromagnetic waves or the like. Therefore, the proximity sensor can operate stably.

  The proximity sensor may further include a second shield electrode provided on the back surface of the substrate opposite to the surface on which the first detection electrode is provided. With the above configuration, when the detected object approaches the proximity sensor from the surface side, the first detection electrode detects the approach of the detected object. On the other hand, when the detected object approaches the proximity sensor from the back side, the second shield electrode shields the detection operation of the first detection electrode. Therefore, it is possible to limit the direction in which the proximity sensor detects the approach of the detection target.

  Furthermore, the second shield electrode may be provided so as not to extend outward from the first detection electrode in a plan view of the surface of the substrate. The above-described configuration suppresses the second shield electrode from reducing the capacitance generated between the first detection electrode and the detection target.

  Further, the shape of the outer periphery of the first detection electrode may be rectangular. With the above-described configuration, the outer circumference of the first detection electrode can be made longer than when the first detection electrode is a circle, an ellipse, an oval, or the like. Therefore, the overall size of the first detection electrode and the first shield electrode can be reduced while increasing the sensitivity of the first detection electrode.

  The shield electrode may be provided so as to fill a region inside the detection electrode around the shield electrode. With the above-described configuration, the area of the shield electrode can be increased. When a deposit such as a water droplet adheres to the surfaces of the shield electrode and the detection electrode, a capacitance is generated between the deposit and the detection electrode. In this electrostatic capacity, since the electrostatic capacity of the shield electrode having a large area becomes dominant, the sensitivity of the detection electrode to the deposit can be kept low.

  The proximity sensor includes at least one detection electrode and at least one shield electrode, and among the at least one detection electrode and the at least one shield electrode, the outermost electrode may be a detection electrode. Good. In the above-described configuration, the outermost detection electrode is not surrounded by the shield electrode. Therefore, it is suppressed that the detection range of the detection electrode is limited by the shield electrode.

  Further, the proximity sensor may include a plurality of detection electrodes, and the shield electrode may be provided around the detection electrodes. In the above-described configuration, the configuration including the detection electrode and the shield electrode around the detection electrode is effective for detecting the detection target when the distance between the detection electrode and the detection target is sufficiently short. On the other hand, the configuration of the shield electrode and the detection electrode around the shield electrode is effective for detection of the detected object when the distance between the detection electrode and the detected object is sufficiently large. Thus, the proximity sensor may have an effective suitability for the two detections.

  Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

  The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(Embodiment 1)
Hereinafter, the proximity sensor 100 according to the first embodiment will be described with reference to FIGS.

[1-1. Constitution]
The configuration of the proximity sensor 100 according to Embodiment 1 will be described with reference to FIG. FIG. 1 is a block diagram of a proximity sensor 100 according to the first embodiment. The proximity sensor 100 includes a sensor unit 200 and a circuit unit 300. The circuit unit 300 includes a detection unit 310 that detects a signal from the sensor unit 200, a communication unit 320 that communicates from the proximity sensor 100 to an external device, and a control unit 330 that controls the detection unit 310 and the communication unit 320. .

  The proximity sensor 100 is for detecting the approach of the detection target, and can be used for various purposes. A specific application example of the proximity sensor 100 will be described later.

  The sensor unit 200 is a capacitance type sensor, and details will be described later.

  The detection unit 310 may be configured by a circuit, for example, and may include a power source, a charge / discharge circuit, a charge / voltage conversion circuit (CV conversion circuit), and the like. The detection unit 310 applies a voltage to the sensor unit 200, detects the electric charge charged in the sensor unit 200 due to the approach of the detected object, and converts it into a voltage. Here, the detection unit 310 is an example of a drive unit and a detection unit.

  The control unit 330 controls the detection unit 310 and the communication unit 320, but may control the entire proximity sensor 100. Further, as will be described later, the control unit 330 determines whether or not the voltage of the sensor unit 200 detected by the detection unit 310 has exceeded a threshold value. The control unit 330 may be, for example, a circuit such as an MPU (Micro Processing Unit), a CPU (Central Processing Unit), a processor, or an LSI (Large Scale Integration).

  The communication unit 320 communicates the result determined by the control unit 330 to an external device by wireless communication such as Wi-Fi (registered trademark) (Wireless Fidelity). The communication unit 320 may be a communication circuit, for example.

  Next, details of the sensor unit 200 will be described with reference to FIG. FIG. 2 is an external view of the sensor unit 200 according to the first embodiment. 2 is a plan view of the sensor unit 200, a cross-sectional view of the sensor unit 200 along the line XX ′ along the length of the sensor unit 200, and a line YY ′ perpendicular to the line XX ′. 2 is a cross-sectional view of the sensor unit 200. The sensor unit 200 includes a rigid printed circuit board (RPC), a flexible printed circuit board (FPC), and the like. The sensor unit 200 has a rectangular planar shape in the present embodiment, but is not limited to this, and may have any shape.

  Specifically, the sensor unit 200 is configured to include an insulating substrate 210 and an electrode pattern formed by a first shield electrode 220 and a first detection electrode 230 that are patterned on the surface of the insulating substrate 210. The first shield electrode 220 and the first detection electrode 230 are electrically connected to the detection unit 310. In the sensor unit 200, the electric field of the first detection electrode 230 is affected by the approaching detection target, whereby the first detection electrode 230 is charged. Based on this charged electric charge, it is possible to detect the approach of the detection object. The first shield electrode 220 reduces the influence that the detection accuracy based on the charge of the first detection electrode 230 is affected by the surrounding object of the detection target. Here, the insulating substrate 210 is an example of a substrate.

  The insulating substrate 210 is made of an electrically insulating material such as an epoxy resin, a phenol resin, polyethylene terephthalate (PET), or polyethylene naphthalate (PEN). The first shield electrode 220 and the first detection electrode 230 are made of a conductive material such as copper, aluminum, or indium tin oxide (ITO).

  The first shield electrode 220 is formed in a polygonal shape (rectangular in the present embodiment) in a plan view of the surface of the insulating substrate 210, and the first detection electrode 230 is formed outside the outer peripheral edge thereof. The first shield electrode 220 is provided so as to fill a region inside the first detection electrode 230, and thereby has a larger area than the first detection electrode 230. In addition to the polygon, the polygonal shape may include a polygon including a rounded corner, a polygon including a curved side, and the like.

  The first detection electrode 230 has a polygonal shape (rectangular in the present embodiment) and has a frame shape surrounding the first shield electrode 220. In addition to the polygon, the polygonal shape may include a polygon including a rounded corner, a polygon including a curved side, and the like. The first detection electrodes 230 are formed at equal intervals from the first shield electrode 220. Specifically, the first detection electrode 230 is disposed with a gap having a certain width from the first shield electrode 220 and is formed with a certain width. Thereby, the first detection electrode 230 is electrically insulated from the first shield electrode 220. The width of the first detection electrode 230 is a width in a direction perpendicular to the outer peripheral edge thereof. Further, the first detection electrode 230 is disposed along the outer peripheral edge of the insulating substrate 210. Specifically, as shown in each cross-sectional view of FIG. 2, the outer peripheral edge of the first detection electrode 230 is substantially flush with the outer peripheral edge of the insulating substrate 210, that is, substantially on the same plane. . Thereby, regarding the detection range that is a range in which the electric field of the first detection electrode 230 can be influenced by the detection target, the limitation of the detection range by the insulating substrate 210 is suppressed. That is, the limit of the detection range of the sensor unit 200 by the insulating substrate 210 can be suppressed.

  Regarding the dimensions related to the sensor unit 200 according to the first embodiment, the size of the sensor unit 200 is about 25 mm × 80 mm, the width of the first detection electrode 230 is about 2 mm, and the distance between the first detection electrode 230 and the first shield electrode 220. The width of the gap is about 1 mm, the dimension of the first shield electrode 220 is about 19 mm × 74 mm, and the thickness of the insulating substrate 210 is about 1.5 to 3 mm. However, the technology in the present disclosure is not limited to these. Absent. The insulating substrate 210 has a thickness in a direction perpendicular to the surface on which the first shield electrode 220 and the first detection electrode 230 are formed. As will be described later, it is desirable that the area of the first shield electrode 220 on the surface of the insulating substrate 210 is larger than the area of the first detection electrode 230.

  In the proximity sensor 100 according to the present embodiment, the detection unit 310 is configured to apply a voltage so that the first shield electrode 220 and the first detection electrode 230 have the same potential. Here, an example of the configuration of the detection unit 310 according to the present embodiment having a configuration in which the first shield electrode 220 and the first detection electrode 230 are set to the same potential will be described with reference to FIG. FIG. 3 is a schematic diagram illustrating an example of the configuration of the detection unit 310 of the proximity sensor 100 of FIG.

  Referring to FIG. 3, the detection unit 310 includes a charge-voltage conversion circuit (hereinafter referred to as a CV conversion circuit) 311 and a power supply circuit 312. The CV conversion circuit 311 includes an operational amplifier 311a and a capacitor 311b. The power supply circuit 312 is connected to the first shield electrode 220 and the non-inverting input terminal of the operational amplifier 311a. An inverting input terminal of the operational amplifier 311 a is connected to the first detection electrode 230, and an output terminal of the operational amplifier 311 a is connected to the control unit 330. The capacitor 311b is connected to a path upstream of the inverting input terminal of the operational amplifier 311a and a path downstream of the output terminal of the operational amplifier 311a. The first detection electrode 230 may or may not be grounded. In the present embodiment, the first detection electrode 230 is configured such that no voltage is applied by the power supply circuit 312, and the first shield electrode 220 is configured such that the voltage is applied by the power supply circuit 312.

  With the above-described configuration, the power supply circuit 312 applies a voltage to the first shield electrode 220 so as to give a potential equivalent to the potential of the first detection electrode 230. In this state, when the detection object approaches the first detection electrode 230, as will be described later, the capacitance generated between the detection object and the first detection electrode 230 increases. The detection electrode 230 is charged. The charge charged in the first detection electrode 230 is converted into a voltage by the CV conversion circuit 311 and output to the control unit 330. An analog / digital converter (A / D converter) may be provided between the output terminal of the operational amplifier 311 a and the control unit 330, and the A / D converter may be included in the control unit 330. Good. The A / D converter converts an analog signal of a voltage output from the output terminal of the operational amplifier 311a into a digital signal.

[1-2. Operation]
The operation of the proximity sensor 100 according to the first embodiment configured as described above will be described. Referring to FIGS. 1 and 2, when the proximity sensor 100 is turned on, the detection unit 310 applies a voltage so that the first shield electrode 220 and the first detection electrode 230 have the same potential. Specifically, the detection unit 310 drives the first shield electrode 220 so that the same potential as the first detection electrode 230 is applied to the first shield electrode 220.

  In this state, when the detected object approaches the sensor unit 200, the capacitance Ca is generated between the detected object and the first detection electrode 230 with the approach of the detected object, and the detected object and the first A capacitance Cs is generated between the shield electrode 220 and the shield electrode 220. The capacitances Ca and Cs increase as the detection target approaches the first detection electrode 230.

  The detection unit 310 converts the capacitance Ca into the voltage Va. The controller 330 determines whether the voltage Va converted by the detector 310 exceeds a predetermined threshold. When the voltage Va exceeds a predetermined threshold value, the control unit 330 determines that the detected object is in a predetermined approach state. The controller 330 recognizes the approach of the detected object based on the determination result.

  The control unit 330 outputs this authorization result to an external device via the communication unit 320.

  Since the first shield electrode 220 and the first detection electrode 230 have the same potential, charge is not charged or discharged between the first shield electrode 220 and the first detection electrode 230, and the apparent static electricity between the two is not detected. The capacitance is equivalently zero. For this reason, the change in the capacitance Cs does not affect the capacitance Ca.

Here, the reason why the sensor unit 200 is formed as described above will be described in detail. In general, in a capacitance type sensor, the capacitance generated between the detection electrode of the sensor and the detected object depends on the area of the detection electrode when the distance between the detection electrode and the detected object is sufficiently close. To do. On the other hand, when the distance between the detection electrode and the detection object is sufficiently large, the fringe capacitance is dominant in the capacitance between the detection electrode and the detection object. For example, the distance (referred to as distance d1) when the distance between the detection electrode and the detection target is sufficiently short can be a distance that satisfies d1 ² <S. S is the area of the detection electrode. Thereby, for example, in the case of the sensor unit 200 having a size of about 25 mm × 80 mm exemplified in the present embodiment, the distance d1 can be less than about 20 mm. Further, the distance d2 when the distance between the detection electrode and the detection object is sufficiently large can be about 50 mm or more.

  The electrode pattern of the sensor unit 200 according to the present embodiment uses the above two properties. Regarding the detection of the detection object by the sensor unit 200, specifically, the detection when the distance between the detection electrode and the detection object is sufficiently large, the advantage of the electrode pattern of the present embodiment is calculated using a calculation model. I will explain.

  First, the results of comparing and examining the capacitance generated between the first detection electrode and the detection target when the arrangement of the electrode pattern of the sensor unit is changed will be described with reference to FIGS. In this examination, the sensor unit of Example 1 of the present embodiment and the sensor unit of Comparative Example 1 of Example 1 were compared. As described above, Example 1 is a case where the first detection electrode is formed outside the outer periphery of the first shield electrode, and Comparative Example 1 is a case where the first shield electrode is formed outside the outer periphery of the first detection electrode. It is. In the sensor portions of Example 1 and Comparative Example 1, the areas of the first detection electrodes are equal to each other, and the areas of the first shield electrodes are equal to each other. FIG. 4 is a calculation model diagram of the sensor unit 200a of Example 1 of the first embodiment. FIG. 5 is a calculation model diagram of the sensor unit 201a of the first comparative example of the first embodiment. FIG. 6 is a diagram showing the calculation results of the capacitances of the sensor units of Example 1 and Comparative Example 1.

  Referring to FIG. 4, the electrode pattern of the sensor unit 200a according to the first embodiment is formed such that the first detection electrode 230a is on the outer periphery of the first shield electrode 220a. Here, in FIG. 4, the longitudinal direction of the rectangular sensor unit 200a is defined as the y-axis direction, and the short direction of the sensor unit 200a and the direction perpendicular to the y-axis are defined as the x-axis direction. The same applies to the drawings after FIG.

  At this time, the outer length of the first detection electrode 230a in the x-axis direction is 25 mm, the outer length in the y-axis direction is 80 mm, and the electrode width is 2 mm. The length of the first shield electrode 220a in the x-axis direction is 19 mm, and the length in the y-axis direction is 74 mm. Further, the width of the interelectrode gap between the first detection electrode 230a and the first shield electrode 220a is 1 mm.

  On the other hand, referring to FIG. 5, the electrode pattern of the sensor unit 201a of Comparative Example 1 is formed so that the first detection electrode 231a is inside the first shield electrode 221a. The length in the x-axis direction of the first detection electrode 231a is 10 mm, and the length in the y-axis direction is 40.4 mm. The first shield electrode 221a has an outer length in the x-axis direction of 25 mm and an outer length in the y-axis direction of 80 mm. Further, the width of the interelectrode gap between the first detection electrode 231a and the first shield electrode 221a is 1 mm.

  FIG. 6 shows the result of comparing the electrostatic capacitances in the electrode patterns of Example 1 and Comparative Example 1. FIG. 6 is a plot of the respective calculation results, where the horizontal axis is the distance between the detected object and the sensor unit, and the vertical axis is the capacitance between the detected object and the first sensing electrode. is there.

  As shown in FIG. 6, the configuration in which the first detection electrode 230a that is the electrode pattern of the sensor unit 200a is provided on the outer peripheral side (Example 1) is the outer periphery of the first shield electrode 221a that is the electrode pattern of the sensor unit 201a. It can be seen that the capacitance increases compared to the configuration provided on the side (Comparative Example 1). In particular, when the distance is 50 mm, the result is that the capacitance at the sensor unit 200a is about 10 times the capacitance at the sensor unit 201a. The configuration in which the detection electrode is formed on the outer periphery of the shield electrode can effectively use the fringe capacitance for the capacitance than the reverse configuration, so that the capacitance can be increased. The sensitivity of the part can be increased.

  Further, in the configuration in which the first detection electrode 230a is formed outside the outer periphery of the first shield electrode 220a, since the periphery of the first detection electrode 230a is open, the detection range of the first detection electrode 230a is wide. On the other hand, in the configuration in which the first detection electrode 231a is formed inside the first shield electrode 221a, the detection range of the first detection electrode 231a is narrow because the periphery of the first detection electrode 231a is surrounded by the first shield electrode 221a. . For example, in the former case, the detection range of the first detection electrode 230a extends from the front to the side and rearward perpendicular to the insulating substrate 210, and in the latter case, the detection range of the first detection electrode 231a is perpendicular to the insulating substrate 210. Limited to the front.

  Next, with respect to Example 1 and Comparative Example 1, in the case where the size of the sensor unit is changed, the result of comparing and examining the capacitance generated between the first detection electrode and the detection target is shown in FIG. Description will be made with reference to FIG. In this examination, Example 2 in which the size of the sensor unit 200a in Example 1 was changed was compared with Comparative Example 2 in which the size of the sensor unit 201a in Comparative Example 1 was changed. FIG. 7 is a calculation model diagram of the sensor unit 200b according to the second example of the first embodiment. FIG. 8 is a comparative calculation model diagram of the sensor unit 201b of the second comparative example of the second embodiment. FIG. 9 is a diagram showing the calculation results of the capacitances of the sensor units of Example 2 and Comparative Example 2.

  Referring to FIG. 7, the electrode pattern of the sensor unit 200b according to the second embodiment is an electrode pattern in which the first detection electrode 230b is disposed so as to surround the outer periphery of the first shield electrode 220b. Referring to FIG. 8, the electrode pattern of the sensor unit 201b of Comparative Example 2 is an electrode pattern in which the first shield electrode 221b is disposed so as to surround the outer periphery of the first detection electrode 231b.

  Here, as shown in FIG. 7, in the sensor part 200b of Example 2, the lengths of the outer sides of one side of the first detection electrode 230b in the x-axis direction and the y-axis direction are each 80 mm, and the electrode width is 2 mm. The lengths of the first shield electrode 220b in the x-axis direction and the y-axis direction are 74 mm, respectively, and the width of the interelectrode gap between the first detection electrode 230b and the first shield electrode 220b is 1 mm.

  Further, as shown in FIG. 8, in the sensor unit 201b of the comparative example 2, the arrangement of the first detection electrode 231b and the first shield electrode 221b is replaced with the arrangement of the sensor unit 200b of the second embodiment. Yes. That is, the lengths of the outer sides of one side of the first shield electrode 221b in the x-axis direction and the y-axis direction are 80 mm, respectively, and the electrode width is 2 mm. The lengths of the first detection electrode 231b in the x-axis direction and the y-axis direction are each 74 mm, and the width of the interelectrode gap between the first detection electrode 231b and the first shield electrode 221b is 1 mm.

  For the electrode patterns of the sensor units 200b and 201b described in FIG. 7 and FIG. 8, the calculation results of the relationship between the change ratio of the size and the change of the capacitance when the overall size of each electrode pattern is reduced are shown. This is the graph shown in FIG. In FIG. 9, the horizontal axis represents the ratio of the length of the outer periphery of the sensor unit, and the vertical axis represents the change ratio of the capacitance between the detection target and the first detection electrode. The ratio of the outer circumference and the change ratio of the capacitance are the outer circumference after size reduction with respect to the outer circumference and the capacitance of the sensor units 200b and 201b having the above-described dimensions described with reference to FIGS. The ratio of the length and capacitance. Further, the electrostatic capacity is an electrostatic capacity when the distance between the detected object and the sensor unit is 500 mm.

  For example, the outer dimension of the sensor unit is halved in the x-axis direction (length in the x-axis direction is 40 mm, the ratio of the outer circumference length is 0.75) and 1/4 (the length in the x-axis direction is 20 mm, the outer circumference length). The ratio is reduced to 0.625). As a result, as shown in FIG. 9, the configuration in which the first detection electrode 230b is disposed on the outer peripheral side (Example 2) is more than the configuration in which the first shield electrode 221b is disposed on the outer peripheral side (Comparative Example 2). It can be seen that the amount of decrease in capacitance accompanying the reduction in size is small. That is, when the first detection electrode is formed on the outer peripheral side, deterioration of the sensitivity of the sensor unit can be suppressed even if the sensor unit is downsized.

  Therefore, from the results of FIGS. 6 and 9, the configuration in which the detection electrode is formed on the outer periphery of the shield electrode secures a certain level of sensitivity to the object to be detected, while maintaining the sensitivity of the detection unit 200 more than the reverse configuration. The size can be reduced.

  As described above, since the influence of the fringe capacitance on the capacitance increases when detecting the detection target, the area of the sensor portion 200 is reduced in order to reduce the size of the sensor portion 200. However, it is necessary to increase the length of the outer periphery. Therefore, the shape of the sensor unit 200 in plan view is preferably a polygon, particularly a rectangle shown in this embodiment, rather than a circle, an ellipse, an oval, or the like.

  In addition, there may be cases where deposits such as water droplets adhere to the surface of the sensor unit 200 due to, for example, rain, snow, or condensation. In this case, an electrostatic capacitance corresponding to the case where the distance between the detection electrode and the detection target is sufficiently short is generated between the detection electrode and the deposit due to the deposit. Therefore, this electrostatic capacity depends on the areas of the detection electrode and the shield electrode.

  At this time, in the electrostatic capacitance generated in the sensor unit 200 due to adhered matter such as water droplets, the electrostatic capacitance of the first shield electrode 220 having a large area is dominant, and the electrostatic capacitance of the first detection electrode 230 having a small area is small. As a result, the sensitivity of the sensor unit 200 to the attached matter can be lowered. Accordingly, it is desirable that the area of the first shield electrode 220 is larger than the area of the first detection electrode 230.

[1-3. Effect]
As described above, in the proximity sensor 100 according to the present embodiment, since the first detection electrode 230 is disposed on the outer periphery, that is, around the first shield electrode 220, the first detection electrode 230 and the first shield electrode 220 are used. Even if the entire size of the sensor unit 200 is small, it is possible to ensure a predetermined capacitance. Thereby, the proximity sensor 100 can be reduced in size easily.

  In addition, by arranging the first detection electrode 230 and the first shield electrode 220, even if the size of the sensor unit 200 is small, the sensitivity of the sensor unit 200 to an object to be detected is increased, and the sensitivity to attached substances such as water droplets is increased. Can be reduced. Therefore, the proximity sensor 100 enables downsizing of the capacitive sensor that can detect the approach of the detection target while preventing erroneous detection.

(Embodiment 2)
Hereinafter, the proximity sensor according to the second embodiment will be described with reference to FIG. In the proximity sensor according to the second embodiment, the configuration of the sensor unit is different from the configuration of the sensor unit 200 according to the first embodiment, and other configurations are the same as those of the first embodiment. For this reason, description of the same structure as Embodiment 1 is abbreviate | omitted.

[2-1. Constitution]
FIG. 10 is a schematic diagram of the sensor unit 2200 of the proximity sensor according to the second embodiment. In the sensor unit 2200 of the proximity sensor according to the second embodiment, a second detection electrode 240 is formed inside the first detection electrode 230 in addition to the configuration of the sensor unit 200 according to the first embodiment. Specifically, the second detection electrode 240 is formed between the first detection electrode 230 and the first shield electrode 220 and is formed in a frame shape surrounding the outer periphery of the first shield electrode 220. The second detection electrode 240 is disposed with a certain width gap from each of the first detection electrode 230 and the first shield electrode 220, and is formed with a certain width. Thereby, the second detection electrode 240 is electrically insulated from the first detection electrode 230 and the first shield electrode 220. The second detection electrode 240 is electrically connected to the detection unit 310.

  The detection unit 310 applies a voltage so that the first detection electrode 230, the second detection electrode 240, and the first shield electrode 220 configured as described above have the same potential. Here, an example of the configuration of the detection unit 310 according to the present embodiment having a configuration in which the first detection electrode 230, the second detection electrode 240, and the first shield electrode 220 are set to the same potential will be described with reference to FIG. . FIG. 11 is a schematic diagram illustrating an example of the configuration of the detection unit 310 of the proximity sensor according to the second embodiment.

  Referring to FIG. 11, the detection unit 310 includes a first CV conversion circuit 311, a second CV conversion circuit 313, an operational amplifier 314, and a power supply circuit 312. Each of the first and second CV conversion circuits 311 and 313 includes an operational amplifier 311a and a capacitor 311b. The power supply circuit 312 is connected to the first shield electrode 220. Further, the power supply circuit 312 is connected to the non-inverting input terminal of the operational amplifier 311 a of the first and second CV conversion circuits 311 and 313. The inverting input terminal of the operational amplifier 311 a of the first CV conversion circuit 311 is connected to the first detection electrode 230, and the output terminal of the operational amplifier 311 a is connected to the inverting input terminal of the operational amplifier 314. The inverting input terminal of the operational amplifier 311 a of the second CV conversion circuit 313 is connected to the second detection electrode 240, and the output terminal of the operational amplifier 311 a is connected to the non-inverting input terminal of the operational amplifier 314. The output terminal of the operational amplifier 314 is connected to the control unit 330. The capacitor 311b of the first CV conversion circuit 311 is connected upstream of the inverting input terminal of the operational amplifier 311a of the first CV conversion circuit 311 and downstream of the output terminal of the operational amplifier 311a. The capacitor 311b of the second CV conversion circuit 313 is connected to the upstream of the inverting input terminal of the operational amplifier 311a of the second CV conversion circuit 313 and the downstream of the output terminal of the operational amplifier 311a. The first detection electrode 230 and the second detection electrode 240 may or may not be grounded. In the present embodiment, the first detection electrode 230 and the second detection electrode 240 are configured such that no voltage is applied by the power supply circuit 312, and the first shield electrode 220 is configured such that a voltage is applied by the power supply circuit 312. Yes.

  With the above-described configuration, the power supply circuit 312 applies a voltage to the first shield electrode 220 so as to apply a potential equivalent to the potentials of the first detection electrode 230 and the second detection electrode 240. Thereby, the electric potential of the 1st sensing electrode 230, the 2nd sensing electrode 240, and the 1st shield electrode 220 is made equivalent. In this state, when the detection target approaches the first detection electrode 230 and the second detection electrode 240, the first detection electrode 230 and the second detection electrode 240 are charged with an increase in capacitance. The charge charged in the first detection electrode 230 is converted into a voltage by the first CV conversion circuit 311 and output to the controller 330. The charge charged in the second detection electrode 240 is converted into a voltage by the second CV conversion circuit 313 and output to the controller 330. Note that an A / D converter may be provided between the output terminal of the operational amplifier 314 and the control unit 330, and the A / D converter may be included in the control unit 330.

[2-2. Operation]
The operation of the proximity sensor according to the second embodiment configured as described above will be described. Referring to FIGS. 1 and 10, when the proximity sensor is turned on, the detection unit 310 applies a voltage so that the first shield electrode 220, the first detection electrode 230, and the second detection electrode 240 have the same potential. .

  In this state, when the detection object approaches the sensor unit 2200 of the proximity sensor, a capacitance Ca is generated between the detection object and the first detection electrode 230 as the detection object approaches, and the detection object is detected. And the second detection electrode 240 generate a capacitance Cb. These capacitances Ca and Cb increase as the detection target approaches the first detection electrode 230 and the second detection electrode 240.

  The detection unit 310 converts the capacitances Ca and Cb into voltages Va and Vb, respectively. The control unit 330 determines whether the difference between the voltages Va and Vb converted by the detection unit 310, specifically, the absolute value of Va−Vb exceeds a predetermined threshold value. When the voltage difference exceeds a predetermined threshold, the control unit 330 determines that the detection target is in a predetermined approach state. The controller 330 recognizes the approach of the detected object based on the determination result.

  Since the first detection electrode 230 is outside the second detection electrode 240, Ca> Cb is satisfied when determining the approach of the detection target. Therefore, the voltage difference can be obtained by subtracting the voltage Vb of the second detection electrode 240 from the voltage Va of the first detection electrode 230.

  The control unit 330 outputs the authorization result to an external device via the communication unit 320.

  Since the first detection electrode 230, the second detection electrode 240, and the first shield electrode 220 are at the same potential, charge is not charged or discharged between the electrodes, and the apparent capacitance between the two is Each is equivalently zero. For this reason, the change in each capacitance does not affect other capacitances.

  In addition, about the influence on the sensor part 2200 by deposits, such as a water droplet, the sensitivity with respect to the deposit of the 1st detection electrode 230 and the 2nd detection electrode 240 becomes low with the 1st shield electrode 220 similarly to Embodiment 1. FIG.

[2-3. Effect]
As described above, in the proximity sensor according to the second embodiment, since the first detection electrode 230 is disposed on the outer periphery of the first shield electrode 220, the first detection electrode 230, the second detection electrode 240, and the first detection electrode are arranged. Even if the entire size of the sensor unit 2200 by the shield electrode 220 is small, a predetermined capacitance can be secured. Thereby, a proximity sensor can be reduced in size easily.

  Further, by arranging the detection electrode and the shield electrode, even when the size of the sensor unit 2200 is small, the sensitivity of the sensor unit 2200 with respect to the detection target can be increased, and the sensitivity with respect to a deposit such as a water droplet can be reduced. . Therefore, the proximity sensor enables downsizing of the capacitive sensor that can detect the approach of the detection target while preventing erroneous detection.

  In addition, by using the difference in voltage change between the first detection electrode 230 and the second detection electrode 240, the influence on the detection accuracy of the sensor unit 2200 due to environmental noise caused by electromagnetic switching such as illumination switching or radio. Can be reduced. Specifically, environmental noise can be canceled by the difference in voltage change. Therefore, the proximity sensor can operate more stably.

(Embodiment 3)
Hereinafter, the proximity sensor according to Embodiment 3 will be described with reference to FIG. In the proximity sensor according to the third embodiment, the sensor unit has a configuration in which a shield electrode is added to the back surface of the insulating substrate of the sensor unit 2200 according to the second embodiment. It is the same. For this reason, description of the same structure as Embodiment 2 is omitted.

[3-1. Constitution]
FIG. 12 is a schematic diagram of a sensor unit 3200 of the proximity sensor according to the third embodiment. FIG. 12 shows a plan view of the sensor unit 3200 and a cross-sectional view of the sensor unit 3200 along the YY ′ line along the short side of the rectangular sensor unit 3200. As shown in FIG. 12, in the sensor unit 3200, the first shield electrode 220, the first detection electrode 230, and the second detection electrode 240 are on the back surface that is the surface of the insulating substrate 210 on the opposite side across the insulating substrate 210. In addition, the second shield electrode 250 is formed.

  As shown in the cross-sectional view of FIG. 12, the electrode outer peripheral edge of the second shield electrode 250 is the same position as the electrode outer peripheral edge of the first detection electrode 230 in the plan view of the surface of the insulating substrate 210, or the first It is located inside the outer peripheral edge of the detection electrode 230. That is, the electrode outer peripheral edge of the second shield electrode 250 is formed so as not to extend outward beyond the electrode outer peripheral edge of the first detection electrode 230 in the plan view. Furthermore, the electrode outer peripheral edge of the second shield electrode 250 may be located at the same position as the outer peripheral edge of the insulating substrate 210 or inside the outer peripheral edge of the insulating substrate 210 in a plan view of the surface of the insulating substrate 210. .

  Here, the reason why the electrode outer peripheral edge of the second shield electrode 250 is configured not to extend outward beyond the electrode outer peripheral edge of the first detection electrode 230 in plan view will be described. As described above, when the distance between the detection electrode and the detection object is sufficiently large, the fringe capacitance is dominant in the capacitance between the detection electrode and the detection object. Therefore, if the outer peripheral edge of the second shield electrode 250 extends outward beyond the outer peripheral edge of the first detection electrode 230, the capacitance of the first detection electrode 230 is affected by the influence of the second shield electrode 250. It will decrease. Therefore, in order to reduce the influence on the first detection electrode, the second shield electrode 250 is configured such that the outer periphery of the electrode does not extend outward beyond the outer periphery of the first detection electrode 230. The

  The second shield electrode 250 configured as described above is connected to the detection unit 310 of FIG. A voltage having the same potential as that of the first shield electrode 220, the first detection electrode 230, and the second detection electrode 240 is supplied to the second shield electrode 250 by the detection unit 310. Here, an example of the configuration of the detection unit 310 according to the present embodiment having a configuration in which the second shield electrode 250, the first shield electrode 220, the first detection electrode 230, and the second detection electrode 240 are set to the same potential is illustrated. 13 will be used for explanation. FIG. 13 is a schematic diagram illustrating an example of the configuration of the detection unit 310 of the proximity sensor according to the third embodiment.

  Referring to FIG. 13, the detection unit 310 has the same configuration as the detection unit 310 of FIG. 11 except that the power circuit 312 is connected to the second shield electrode 250 in addition to the first shield electrode 220. ing. Therefore, in the present embodiment, the voltage is not applied to the first detection electrode 230 and the second detection electrode 240 by the power supply circuit 312, and the voltage is applied to the first shield electrode 220 and the second shield electrode 250 by the power supply circuit 312. It is comprised so that it may be applied. Then, the power circuit 312 applies the first shield electrode 220 and the second shield electrode 250 so that the potentials of the first detection electrode 230, the second detection electrode 240, the first shield electrode 220, and the second shield electrode 250 are equal. It is comprised so that a voltage may be applied. The other configuration of the detection unit 310 is the same as that of the detection unit 310 of FIG.

[3-2. Operation]
The operation of the proximity sensor according to the third embodiment configured as described above will be described. When the detection target approaches the sensor portion 3200 of the proximity sensor in the ON state from the surface on which the first detection electrode 230 is formed, the proximity sensor operates in the same manner as in the first and second embodiments. On the other hand, when the object to be detected approaches from the formation surface side of the second shield electrode 250 which is the back surface opposite to the formation surface of the first detection electrode 230, the second shield electrode 250 has the first detection electrode and the second detection electrode. Since the potential is the same as that of the electrode 240, the detection operation of the first detection electrode 230 and the second detection electrode 240 is shielded. Specifically, the second shield electrode 250 blocks the influence of the detection object on the electric fields of the first detection electrode and the second detection electrode 240. Thereby, since an electrostatic capacitance does not generate | occur | produce between the 1st sensing electrode 230 and the 2nd sensing electrode 240, and a to-be-detected body, a proximity sensor does not detect the approach of a to-be-detected body. Therefore, in the proximity sensor according to the present embodiment, the detection direction of the approach of the detection target can be limited.

[3-3. Effect]
As described above, the proximity sensor according to the third embodiment can detect the approach of the detected object and can detect the approach in the same manner as the proximity sensor according to the first and second embodiments. It can be limited. The same effect can be obtained by adding a second shield electrode to the proximity sensor 100 according to the first embodiment.

  Specifically, the sensor unit 3200 of the proximity sensor according to the third embodiment adds a second shield electrode to the back surface of the formation surface of the first detection electrode 230 in the configuration of the sensor unit 2200 according to the second embodiment. Is formed. However, in the configuration of the sensor unit 200 according to Embodiment 1, the sensor unit may be formed by providing the second shield electrode on the back surface of the surface on which the first detection electrode 230 is formed.

(Other embodiments)
As described above, Embodiments 1 to 3 have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to these, and can be applied to embodiments in which changes, replacements, additions, omissions, and the like are made. Moreover, it is also possible to combine each component demonstrated in the said embodiment and the following other embodiment into a new embodiment. Therefore, other embodiments will be exemplified below.

  In the proximity sensor according to the first to third embodiments, the detection electrode and the shield electrode of the sensor unit are configured by one continuous electrode, but are not limited thereto, and may be configured by a plurality of electrodes. For example, each electrode of the sensor unit may be divided and arranged. For example, the first detection electrode 230 may be divided into four and arranged so as to surround the four sides of the first shield electrode 220.

  In the sensor part of the proximity sensor according to the first to third embodiments, the detection electrode is disposed on the outer periphery of the shield electrode, but is not limited thereto. A shield electrode may be disposed around the outside of the sensing electrode. In this case, it is desirable to provide two or more detection electrodes. Furthermore, it is desirable that a detection electrode be applied to the outermost electrode. The configuration of the shield electrode and the detection electrode positioned inside the shield electrode is effective for detection when the distance between the detection electrode and the detection target is sufficiently short. The configuration using the shield electrode and the detection electrode positioned outside the shield electrode is effective for detection when the distance between the detection electrode and the detection target is sufficiently large. Therefore, the configuration in which the detection electrode is arranged outside and inside the shield electrode is when the distance between the detection electrode and the detection target is sufficiently close, and when the distance between the detection electrode and the detection target is sufficiently large Any of the above may have an effective compatibility. Further, in the latter case, since the detection electrode is located on the outermost side, the detection range of the detection electrode is prevented from being limited by the shield electrode.

  Further, the proximity sensor according to the first to third embodiments can be applied as follows. For example, as shown in FIG. 14, the proximity sensor 100 can be used as a window sensor by being affixed to a window 1 of a building and configured to communicate with a security system in the building.

  In such a configuration, a person becomes a detected object. Specifically, when a person approaches the proximity sensor 100, capacitance is generated in the proximity sensor 100. In the proximity sensor 100, a predetermined threshold is set in advance for such a capacitance. When the capacitance exceeds the threshold value, the proximity sensor 100 determines that a person is approaching.

  Thereby, the proximity sensor 100 can detect that the person approached the window 1 before opening / closing of the window 1, destruction of a window, etc. were implemented. The proximity sensor 100 can be used not only for detecting the occurrence of an abnormality such as opening / closing of the window 1 and destruction of the window 1 but also for crime prevention to prevent the occurrence of the abnormality.

  When the proximity sensor 100 is used as a window sensor, it is preferable that the proximity sensor 100 detects only people outside the building and does not detect people inside the building. In this case, the proximity sensor according to Embodiment 3 that can limit the detection direction is particularly useful.

  In the proximity sensor according to Embodiments 1 to 3, the first shield electrode of the sensor unit may be formed in a frame shape. Accordingly, a device such as a liquid crystal panel, a display device such as an organic or inorganic EL (Electro Luminescence), and a touch sensor can be incorporated in the frame of the first shield electrode.

  Using the proximity sensor configured as described above, a configuration in which the device within the frame of the first shield electrode, that is, the touch sensor and / or the display device can be turned ON / OFF, etc. is realized. Is possible. Further, the detection electrode may be divided into a plurality of parts so that each of them performs independent detection. That is, the plurality of divided detection electrodes constitute a plurality of sensor units. Thereby, the proximity sensor can detect a human gesture or the like, and a device including such a proximity sensor can be used as a device that accepts a gesture input or the like.

  Moreover, the proximity sensor according to Embodiments 1 to 3 can be used in various applications and places other than the above. Proximity sensors can be used to count the number of people passing through the floor, walls, etc., for example by being placed on the floor, walls, etc. The proximity sensor can be used to warn an outsider from entering a predetermined area, for example, by being arranged on a fence or the like.

  In addition, the proximity sensor can be used to diagnose a person's getting out of bed, a person turning over during sleep, a person's pulse, etc. by being placed under a bed or a futon, for example. can do.

  Moreover, the object which a proximity sensor detects can be considered besides a person. The proximity sensor can also detect a vehicle such as a vehicle. For example, the proximity sensor can be disposed in a parking lot or the like and used to detect the presence or absence of a vehicle.

  In addition, since the above-mentioned embodiment is for demonstrating the technique in this indication, a various change, substitution, addition, abbreviation, etc. can be performed in a claim or its equivalent range.

  The proximity sensor of the present disclosure can be detected by reducing the influence of surrounding objects that are not detected, and can be reduced in size, and thus can be applied to various systems such as a window sensor.

DESCRIPTION OF SYMBOLS 100 Proximity sensor 200,2200,3200 Sensor part 210 Insulating substrate 220 1st shield electrode 230 1st detection electrode 240 2nd detection electrode 250 2nd shield electrode 300 Circuit part 310 Detection part 320 Communication part 330 Control part

Claims (8)

A substrate,
A first shield electrode provided on the surface of the substrate;
A first sensing electrode provided around the first shield electrode on the surface of the substrate, the first sensing electrode being insulated from the first shield electrode and having a polygonal outer periphery;
A drive unit in which the first shield electrode and the first detection electrode are connected to each other and power is supplied to the first shield electrode and the first detection electrode. The drive unit applies a voltage so that the first shield electrode and the first detection electrode have the same potential. And
A proximity sensor that detects a change in capacitance of the first detection electrode. A substrate,
A first shield electrode provided on the surface of the substrate;
A first sensing electrode provided around the first shield electrode on the surface of the substrate, wherein the first sensing electrode is insulated from the first shield electrode;
A second sensing electrode provided inside the first sensing electrode on the surface of the substrate, wherein the second sensing electrode is insulated from the first shield electrode and the first sensing electrode;
A driving unit to which the first shield electrode, the first detection electrode, and the second detection electrode are connected and supplied with power, wherein the first shield electrode, the first detection electrode, and the second detection electrode A drive unit for applying a voltage so as to have the same potential;
A proximity sensor, comprising: a detection unit that detects a change in capacitance in the first detection electrode and the second detection electrode.   The proximity sensor according to claim 1, further comprising a second shield electrode provided on a back surface opposite to the surface on which the first detection electrode of the substrate is provided.   The proximity sensor according to claim 3, wherein the second shield electrode is provided so as not to extend outward from the first detection electrode in a plan view of the surface of the substrate.   The proximity sensor according to any one of claims 1 to 4, wherein a shape of an outer periphery of the first detection electrode is a rectangular shape.   The proximity sensor according to any one of claims 1 to 5, wherein the shield electrode is provided so as to fill a region inside the detection electrode around the shield electrode. Comprising at least one sensing electrode and at least one shield electrode;
The proximity sensor according to any one of claims 1 to 6, wherein the outermost electrode among the at least one detection electrode and the at least one shield electrode is the detection electrode. A plurality of the detection electrodes;
The proximity sensor according to claim 7, wherein the shield electrode is provided around the detection electrode.

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