JP5315529B2 - Capacitive proximity sensor, proximity detection method, and electrode structure of capacitive proximity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitive proximity sensor capable of optionally setting an area of a detection region by improving the directivity without requiring a three-dimensional sensor structure, a detection method and an electrode structure. <P>SOLUTION: A capacitive proximity sensor 100 includes a sensor part 10 and a detection circuit part 20. The sensor part 10 includes first sensor electrodes 11a, 11b, a second sensor electrode 11c, a shield electrode 12, first auxiliary electrodes 13a, 13b, and a second auxiliary electrode 13c. These are connected to a positive input terminal P or a negative input terminal N of a C-V conversion circuit 21 of the detection circuit part 20, a shield driving circuit 24, or the like by change over switches SW1 to SW4. The changeover switches SW1 to SW4 are provided on the side 1 and the side 2, and can be selectively switched. The detection range of the sensor part 10 is optionally set by operation such as comparison between the capacitances C1, C2 detected by the C-V conversion circuit 21 upon switching to the side 1 and the side 2 by these changeover switches SW1 to SW4. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a capacitive proximity sensor, a proximity detection method, and an electrode structure of a capacitive proximity sensor that detect proximity of an object to be detected such as a human body by capacitance change.

  For example, the following sensors are known as proximity sensors that approach a detection target such as a human body. The proximity sensor has a bottomed cylindrical fixed shield electrode, a disc-shaped detection board is attached to the open end of the fixed shield electrode, and a sensor electrode facing the detection target is further provided at the center of the detection board. It is set as the provided structure.

  In addition, this proximity sensor has a cylindrical movable shield electrode that can slide along the axial direction outside the fixed shield electrode, thereby adjusting the detectable range and detection sensitivity according to various detection conditions, It is set as the structure which can detect a detection target object reliably (for example, refer patent document 1).

  In order to provide directivity in the proximity sensor in this manner, a range of the sensor electrode in a predetermined direction is defined as a range of the detection region by arranging a shield electrode around or behind the sensor electrode to form a dead zone. It is generally done to be.

JP 2001-35327 A

  However, the proximity sensor having the structure disclosed in Patent Document 1 described above does not detect a detection target such as a human body that is in the immediate vicinity of the sensor electrode, but is located at a location that is at least as large as the electrode size of the sensor electrode. When detecting a detection object, even if a shield electrode is placed around the sensor electrode, the capacitive coupling between the detection object and the sensor electrode hardly decreases, so the directivity is increased. There is a problem that is difficult.

  Moreover, in order to improve directivity, when the shield electrode of the shape which covers a sensor electrode in three dimensions like the proximity sensor described in patent document 1 is arrange | positioned, a sensor structure will become three-dimensional. For this reason, there is a problem that the size of the entire sensor is increased and the accumulation of sensor electrodes is increased, so that the sensor cannot be arranged in a plane and the degree of freedom in arrangement is significantly reduced.

  In order to eliminate the above-described problems caused by the prior art, the present invention can improve the directivity and arbitrarily set the detection area range without using a three-dimensional sensor structure and without reducing the degree of freedom of arrangement. It is an object of the present invention to provide a capacitive proximity sensor, a proximity detection method, and an electrode structure of a capacitive proximity sensor that can detect a detection object reliably.

  In order to solve the above-described problems and achieve the object, a first capacitive proximity sensor according to the present invention includes a first sensor electrode and a second sensor electrode provided in the vicinity of the first sensor electrode. A first auxiliary electrode provided in the vicinity of the first and second sensor electrodes, a second auxiliary electrode provided in the vicinity of the first auxiliary electrode, a positive input terminal, and a negative input terminal, A capacitance detection circuit that detects a capacitance value that is a difference between a capacitance of an electrode connected to the positive input terminal and a capacitance of an electrode connected to the negative input terminal; and the capacitance detection A shield driving circuit for applying an electric potential equivalent to each input terminal of the circuit to the electrode; at least the first sensor electrode is connected to the positive input terminal; the first auxiliary electrode is connected to the shield driving circuit; A first connection state in which an auxiliary electrode is connected to the negative input terminal; at least the first auxiliary electrode is connected to the positive input terminal; the first sensor electrode is connected to the shield drive circuit; and A changeover switch capable of switching between a second connection state for connecting a sensor electrode to the negative input terminal, a first capacitance value from the capacitance detection circuit in the first connection state, and the first The detection object is within the detection region based on the comparison value obtained by comparing the second capacitance value from the capacitance detection circuit in the connection state 2 and the first or second capacitance value. And a comparison / determination unit for determining whether or not the device is in the range.

  In the first connection state, for example, the second sensor electrode is further connected to the positive input terminal, and in the second connection state, for example, the second auxiliary electrode is further connected to the positive input terminal.

  Since the capacitive proximity sensor according to the present invention is configured as described above, the range of the detection region can be arbitrarily set while improving the directivity. Therefore, the detection object can be detected even under various detection conditions. Can be reliably detected. In addition, since a three-dimensional sensor structure is not used, the degree of freedom of sensor placement is high, and it can be applied to various places.

  The first and second sensor electrodes and the first and second auxiliary electrodes are arranged on the back surfaces opposite to the detection surfaces in a state of being insulated from the sensor electrodes and the auxiliary electrodes. Further, a shield electrode for shielding detection on the back side of each electrode may be further provided.

  The first sensor electrode, the second sensor electrode, the first auxiliary electrode, and the second auxiliary electrode may be arranged in a mutually insulated state on the same plane, for example.

  The first sensor electrode may be disposed so as to surround the second sensor electrode from the outer peripheral side.

  Further, the first sensor electrode is formed in a shape having a rectangular portion formed in a rectangular shape and a square shape formed in a square shape surrounding the rectangular portion, for example, and formed in a square shape. The second sensor electrode may be disposed so as to be sandwiched between the rectangular portion and the square-shaped portion.

  The first auxiliary electrode may be disposed so as to surround the second auxiliary electrode from the outer peripheral side.

  In addition, the first auxiliary electrode is formed in a shape having a plurality of square-shaped portions formed in, for example, different square shapes, and the second auxiliary electrode formed in a square shape is You may arrange | position so that it may pinch | interpose between several square-shaped parts.

  The first and second auxiliary electrodes may be disposed so as to surround the first and second sensor electrodes, for example.

  The first sensor electrode, the second sensor electrode, the first auxiliary electrode, and the second auxiliary electrode may be disposed concentrically, for example.

  The comparison determination unit calculates a comparison value by multiplying a value obtained by dividing the first capacitance value by the second capacitance value by a predetermined coefficient, for example, and the comparison value is preset. It is determined whether or not there is a detection target within the detection area depending on whether or not the threshold value is exceeded.

  The capacitance detection circuit includes, for example, a first initial capacitance that is an initial capacitance of the first capacitance value when there is no detection target within the detection region, and a detection target within the detection region. A second initial capacity that is an initial capacity of the second electrostatic capacity value when there is no object, and the comparison and determination means detects the first initial capacity from the first electrostatic capacity value, for example. A comparison value obtained by comparing a first detection value obtained by subtracting a capacitance with a second detection value obtained by subtracting the second initial capacitance from the second capacitance value, and the first or second detection. Based on the value, it is determined whether or not the detection object is within the detection area.

  Further, the apparatus further includes a reference voltage adjusting unit for setting the output of the capacitance detection circuit to a reference voltage, and the capacitance detection circuit is configured to detect the first object when there is no detection target within a detection region, for example. A first set value for adjusting a first initial capacity, which is an initial capacity of the electrostatic capacity value, to the reference voltage, and the second electrostatic capacity when there is no object to be detected within the detection area. A second setting value for setting a second initial capacitance, which is an initial capacitance of the capacitance value, to the reference voltage is acquired from the reference voltage adjusting unit, and the first setting value adjusted by the first setting value is used. An electrostatic capacitance value and a second electrostatic capacitance value adjusted by the second set value are output, and the comparison determination unit is configured to output the first adjusted by the first set value, for example. Subtract the reference voltage from the capacitance value of A comparison value obtained by subtracting the reference voltage from the second capacitance value adjusted by the second setting value as a second detection value, and the first or Based on the second detection value, it is determined whether or not the detection object exists within the detection area.

  For example, when the comparison determination unit determines that the detection target is within the detection region, the first capacitance value, the second capacitance value, the first detection value, and the Based on one of the values of the second detection value, a signal corresponding to the distance of the detection object to at least one of the first and second sensor electrodes is output, and the detection object is within the detection area. When it is determined that there is no output, this output is set to a predetermined fixed voltage.

  Here, the predetermined fixed voltage is, for example, a ground voltage or a reference voltage.

  The proximity detection method according to the present invention has a positive input terminal and a negative input terminal, and includes a first sensor electrode, a second sensor electrode provided in the vicinity of the first sensor electrode, the first and second sensors. Of the first auxiliary electrode provided in the vicinity of the sensor electrode and the second auxiliary electrode provided in the vicinity of the first auxiliary electrode, the capacitance of the electrode connected to the positive input terminal and the negative input terminal A capacitance detection circuit for detecting a capacitance value, which is a difference in capacitance between electrodes connected to each other, and a changeover switch for switching a connection state between these electrodes and each input terminal. A proximity detection method for detecting the proximity of the detection target by a capacitive proximity sensor capable of determining whether or not a detection target is present therein, wherein the position of each electrode is detected by the changeover switch. Switching the connection state to the active input terminal and the negative input terminal, and changing the detection characteristics on the detection surface side, and detecting the capacitance values before and after the change of the detection characteristics by the capacitance detection circuit, A step of obtaining the first and second capacitance values, a comparison value between the first capacitance value and the second capacitance value, and the first or second capacitance value; And a step of determining whether or not there is a detection target within the range of the detection region.

  In this proximity detection method, for example, when there is a detection target in the range of the detection region, the first and second sensor electrodes of the detection target are further based on the first or second capacitance value. You may determine the distance to at least one of these.

  The electrode structure of the capacitive proximity sensor according to the present invention has a positive input terminal and a negative input terminal, and includes a first sensor electrode, a second sensor electrode provided in the vicinity of the first sensor electrode, Among the first auxiliary electrode provided in the vicinity of the first and second sensor electrodes and the second auxiliary electrode provided in the vicinity of the first auxiliary electrode, the capacitance of the electrode connected to the positive input terminal Detection is performed by a capacitance detection circuit that detects a capacitance value that is a difference in capacitance between electrodes connected to the negative input terminal, and a changeover switch that switches a connection state between these electrodes and each input terminal. An electrode structure of a capacitive proximity sensor that can determine whether or not there is a detection object within a region, and is formed in a rectangular shape that is formed in a rectangular shape and a rectangular shape surrounding the rectangular portion. Roo's A first sensor electrode connected to the positive input terminal and having a function of detecting capacitance and a function of shielding the detection; and a first sensor electrode formed in a U shape. A second sensor provided between a rectangular portion and a square-shaped portion of one sensor electrode and connected to the positive input terminal or the negative input terminal to detect a capacitance and a function to shield the detection. The sensor electrode is formed in a shape having a plurality of square-shaped portions formed in a square shape having different sizes, provided on the outer peripheral side of the first and second sensor electrodes, and connected to the positive input terminal. A first auxiliary electrode having a function of detecting electrostatic capacitance and a function of shielding the detection, and is provided between a plurality of square-shaped portions of the first auxiliary electrode formed in a square shape. The positive Characterized in that it consists of a second auxiliary electrode having a function of shielding the features and 該検 known that are connected to the input terminal or the negative input terminal for detecting the electrostatic capacitance.

  According to the present invention, the range of the detection area can be arbitrarily set by improving directivity without using a three-dimensional sensor structure and without reducing the degree of freedom of arrangement, and the detection target can be detected reliably. It is possible to provide a capacitive proximity sensor, a proximity detection method, and an electrode structure of the capacitive proximity sensor that can be performed.

It is the schematic which shows the example of the whole structure of the capacitive proximity sensor concerning 1st Embodiment of this invention. It is explanatory drawing for demonstrating the relationship and the operation | movement concept of the detection target object and electric force line at the time of the detection operation | movement of the same capacitive proximity sensor. It is explanatory drawing for demonstrating the relationship and the operation | movement concept of the detection target object and electric force line at the time of the detection operation | movement of the same capacitive proximity sensor. It is explanatory drawing for demonstrating the relationship and the operation | movement concept of the detection target object and electric force line at the time of the detection operation | movement of the same capacitive proximity sensor. It is explanatory drawing for demonstrating the relationship and the operation | movement concept of the detection target object and electric force line at the time of the detection operation | movement of the same capacitive proximity sensor. It is a flowchart which shows the example of the proximity detection process sequence by the proximity detection method of the capacitive proximity sensor concerning 1st Embodiment of this invention. It is the schematic which shows the other example of the whole structure of the capacitive proximity sensor concerning 1st Embodiment of this invention. It is a flowchart which shows the example of the proximity detection process sequence by the proximity detection method of the same capacitive proximity sensor. It is the schematic which shows the further another example of the whole structure of the electrostatic capacitance type proximity sensor. It is the schematic which shows the example of the whole structure of the capacitive proximity sensor concerning 2nd Embodiment of this invention. It is the schematic which shows the other example of the whole structure of the electrostatic capacitance type proximity sensor. It is the schematic which shows the further another example of the whole structure of the electrostatic capacitance type proximity sensor.

  Exemplary embodiments of a capacitive proximity sensor, a proximity detection method, and an electrode structure of a capacitive proximity sensor according to the present invention will be explained below in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram illustrating an example of the overall configuration of the capacitive proximity sensor according to the first embodiment of the present invention, and FIGS. 2 to 5 are detection objects during the detection operation of the capacitive proximity sensor. It is explanatory drawing for demonstrating the relationship and operation | movement concept of an electric force line. FIG. 6 is a flowchart showing an example of a proximity detection processing procedure by the proximity detection method of the capacitive proximity sensor according to the first embodiment of the present invention.

  As shown in FIG. 1, the capacitive proximity sensor 100 is integrated with a sensor unit 10 disposed at a position where a detection target such as a human body is detected, and the sensor unit 10 via a substrate (not shown). Or it is comprised including the detection circuit part 20 arrange | positioned separately.

  The sensor unit 10 mainly includes, for example, a sensor electrode 11 (11a, 11b, 11c) formed as a rectangular flat plate as a whole, a shield electrode 12 formed on the back side of the sensor electrode 11, and the sensor electrode 11 The auxiliary electrode 13 (13a, 13b, 13c) is formed on the same plane and formed in a square shape so as to surround the sensor electrode 11 from the outer peripheral side as a whole. The sensor electrode 11 and the auxiliary electrode 13 are disposed in a state of being insulated from each other. The shield electrode 12 is preferably larger than the sensor electrode 11 in order to reduce the sensitivity of the back surface.

  The sensor electrode 11 includes first sensor electrodes 11a and 11b and a second sensor electrode 11c provided in the vicinity of the first sensor electrodes 11a and 11b. The first sensor electrodes 11a and 11b are, in this example, a first sensor electrode 11a which is a rectangular portion formed in a rectangular shape, and a square shape portion formed in a square shape surrounding the first sensor electrode 11a. The first sensor electrode 11b is formed into a shape.

  The second sensor electrode 11c is also formed in a square shape, and is disposed so as to be sandwiched between the first sensor electrodes 11a and 11b.

  The auxiliary electrode 13 includes first auxiliary electrodes 13a and 13b provided in the vicinity of the sensor electrode 11, and a second auxiliary electrode 13c provided in the vicinity of the first auxiliary electrodes 13a and 13b. In this example, the first auxiliary electrodes 13a and 13b are formed in a shape composed of a plurality of square-shaped portions having different square shapes.

  The second auxiliary electrode 13c is also formed in a square shape and is disposed so as to be sandwiched between the first auxiliary electrodes 13a and 13b.

  And the auxiliary electrode 13 (namely, 1st and 2nd auxiliary electrode 13a-13c) is arrange | positioned so that the sensor electrode 11 (namely, 1st and 2nd sensor electrode 11a-11c) may be enclosed, and these are concentric. Is arranged. The shield electrode 12 is arranged in a state of being insulated with the sensor electrode 11 on the back side opposite to the detection surface of the auxiliary electrode 13, and shields detection on the back side of the sensor electrode 11 and the auxiliary electrode 13. ing.

  On the other hand, the detection circuit unit 20 includes capacitances connected to the first and second sensor electrodes 11a and 11b and the first and second auxiliary electrodes 13a and 13b via changeover switches SW1, SW2, SW3, and SW4. A CV conversion circuit 21 serving as a detection circuit, an A / D converter 22, a CPU 23, and a shield drive circuit 24 are provided.

  The CV conversion circuit 21 converts capacitance (Capacitance) detected by each electrode into voltage (Voltage). The A / D converter 22 converts an analog signal indicating a voltage from the CV conversion circuit 21 into a digital signal. The CV conversion circuit 21 has a differential input type configuration having a positive input terminal P and a negative input terminal N in this example.

  Therefore, in the CV conversion circuit 21, the difference between the electrostatic capacitance between the positive input terminal P and the ground (GND) and the electrostatic capacitance between the negative input terminal and the ground (GND) is a voltage. It is configured to be converted and output to the A / D converter 22. Each of the switches SW1 to SW4 has a structure that can be switched to, for example, 1 side or 2 side, and is connected as follows in this example.

  The change-over switch SW1 is connected to the first sensor electrodes 11a and 11b, and when switched to one side, the first sensor electrodes 11a and 11b are connected to the positive input terminal P of the CV conversion circuit 21 and to the second side. When switched, these are connected to the shield drive circuit 24. The change-over switch SW2 is connected to the first auxiliary electrodes 13a and 13b. When switched to the 1 side, the first auxiliary electrodes 13a and 13b are connected to the shield drive circuit 24, and when switched to the 2 side, these are switched. The positive input terminal P of the CV conversion circuit 21 is connected.

  The changeover switch SW3 is connected to the second sensor electrode 11c, and when switched to the 1 side, connects the second sensor electrode 11c to the positive input terminal P of the CV conversion circuit 21 and when switched to the 2 side. Is connected to the negative input terminal N of the CV conversion circuit 21. The changeover switch SW4 is connected to the second auxiliary electrode 13c, and when switched to the 1 side, connects the second auxiliary electrode 13c to the negative input terminal N of the CV conversion circuit 21 and when switched to the 2 side. Is connected to the positive input terminal P of the CV conversion circuit 21.

  These change-over switches SW1 to SW4 may have any structure as long as the electrical connection can be switched. For example, electronic switches such as FETs and photo MOS relays and mechanical switches such as contact point switches are all used. Can be adopted. In addition, the sensor electrode 11 and the auxiliary electrode 13 can be configured in various shapes such as a circle, a rectangle, and a polygon as well as a rectangle or a square shape, and the back side of the sensor electrode 11 is also set as a detection range. In this case, a configuration in which the shield electrode 12 is not disposed can be employed.

  Furthermore, although the auxiliary electrode 13 is disposed so as to surround the entire periphery of the sensor electrode 11, for example, the auxiliary electrode 13 may be disposed so as to surround a part thereof, or may be disposed in a part adjacent to the sensor electrode 11.

  The CPU 23 controls the entire capacitive proximity sensor 100, controls the operation of the changeover switches SW1 to SW4, and determines the detection of the detection target in the detection region (the presence or absence of the detection target). The shield drive circuit 24 has a potential equivalent to at least one of the first sensor electrodes 11a and 11b and the first auxiliary electrodes 13a and 13b connected by switching the changeover switches SW1 to SW4, for example, directly connected shield electrodes. 12 is also driven. In other words, the shield drive circuit 24 applies potentials equivalent to those of the positive input terminal P and the negative input terminal N of the CV conversion circuit 21 to the connected electrodes.

  The sensor unit 10 and the detection circuit unit 20 are formed on a substrate (not shown), for example. As this board | substrate, any board | substrate of a flexible printed board, a rigid board | substrate, or a rigid flexible board | substrate is employable, for example. The sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13 are on a substrate made of an insulator such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polyamide (PA), glass epoxy resin, or ceramic. It can be composed of copper, copper alloy, metal parts (conductive material) such as aluminum and iron, electric wires, and the like.

  Next, an operation example of the capacitive proximity sensor 100 configured as described above will be described. First, an operation (operation 1) when the switches SW1 to SW4 are switched to the 1 side under the control of the CPU 23 will be described. Note that the illustrated detection object A is a detection object within the detection range of the sensor unit 10, and the detection object B is a detection object outside the detection range of the sensor unit 10.

  In the case of the operation 1 in which the selector switches SW1 to SW4 are switched to the 1 side, the first and second sensor electrodes 11a to 11c and the first and second auxiliary electrodes 13a to 13a in the sensor unit 10 of the capacitive proximity sensor 100. The connection state with the detection circuit unit 20 of 13c is as shown in FIGS.

  That is, the first sensor electrodes 11 a and 11 b and the second sensor electrode 11 c are connected to the positive input terminal P of the CV conversion circuit 21, and the second auxiliary electrode 13 c is connected to the negative input terminal N. At the same time, the shield electrode 12 and the first auxiliary electrodes 13 a and 13 b are connected to the shield drive circuit 24.

  Therefore, in this operation 1, the capacitances of the detection objects A and B are converted into CV by the first and second sensor electrodes 11a to 11c and the second auxiliary electrode 13c as shown in FIG. It is detected by the circuit 21.

  At this time, the back surfaces of the sensor electrode 11 and the auxiliary electrode 13 are covered with the shield electrode 12 connected to the shield drive circuit 24, and therefore the back surfaces of the sensor electrode 11 and the auxiliary electrode 13 are covered. It is assumed that the sensor sensitivity is equal to a state where there is almost no sensor sensitivity. The same applies to operation 2 described later.

  Further, it is assumed that the detection object A shown in FIG. 2A and the detection object B shown in FIG. 2B are at substantially the same distance from the first sensor electrodes 11a and 11b. Here, as shown in FIG. 2A, the detection target A is a detection target within the detection range because it exists above the first sensor electrodes 11a and 11b, and as shown in FIG. Since the detection target B exists on the upper outer side (the upper side of the auxiliary electrode 13) of the second sensor electrode 11c, the detection target B is a detection target outside the detection range.

  Since it can be said that the detection target A is close to the first and second sensor electrodes 11a to 11c connected to the positive input terminal P of the CV conversion circuit 21, electric lines of force with these sensor electrodes 11a to 11c It can be said that the bond by F1 is strong. The second auxiliary electrode 13c connected to the negative input terminal N of the CV conversion circuit 21 is far from the detection target A, and the first auxiliary electrodes 13a and 13b connected to the shield drive circuit 24 are also detection targets. It can be said that it is far from the object A.

  For this reason, the coupling of the auxiliary electrodes 13a to 13c and the detection target A by the electric force lines F2 is weaker than the electric force lines F1, and the capacitance detected by the CV conversion circuit 21 is increased.

  Next, the detection target B existing on the upper outside of the sensor unit 10 with respect to the detection target A is from the first and second sensor electrodes 11 a to 11 c connected to the positive input terminal P of the CV conversion circuit 21. Since it can be said that it is far, it can be said that the coupling by the electric lines of force F1 with these sensor electrodes 11a to 11c is weak. In addition, the second auxiliary electrode 13c connected to the negative input terminal N of the CV conversion circuit 21 is close to the detection target B, and the first auxiliary electrodes 13a and 13b connected to the shield drive circuit 24 are also detection targets. It can be said that it is close to thing B.

  For this reason, the coupling of the auxiliary electrodes 13a to 13c and the detection target B by the electric force lines F2 is stronger than the electric force lines F1, and the capacitance detected by the CV conversion circuit 21 is the detection target. It becomes smaller than the case of A. Therefore, in the case of this operation 1, it is possible to distinguish the detection objects A and B, and the CPU 23 stores the first capacitance value C1 by the output from the CV conversion circuit 21 at this time. .

  In addition, as shown in FIG. 3, in the case of the detection target B ′ closer to the sensor unit 10 than the detection target B, as compared with the detection target B shown in FIG. The coupling between the first and second sensor electrodes 11a to 11c and the detection object B ′ by the electric lines of force F1 greatly increases. Accordingly, if the increase in the coupling between the first and second auxiliary electrodes 13a to 13c and the detection target B ′ due to the electric lines of force F2 is small, the detection target A and the detection target B ′ shown in FIG. Since the output from the CV conversion circuit 21 is the same, the detection object B ′ cannot be out of the detection range only in the state of the operation 1.

  Therefore, next, an operation (operation 2) when the switches SW1 to SW4 are switched to the 2 side under the control of the CPU 23 will be described. In the case of the operation 2 in which the selector switches SW1 to SW4 are switched to the second side, the first and second sensor electrodes 11a to 11c and the first and second auxiliary electrodes 13a to 13a in the sensor unit 10 of the capacitive proximity sensor 100 are used. The connection state with the detection circuit unit 20 of 13c is as shown in FIG. 4 and FIG.

  That is, the first auxiliary electrodes 13a and 13b and the second auxiliary electrode 13c are connected to the positive input terminal P of the CV conversion circuit 21, and the second sensor electrode 11c is connected to the negative input terminal N. At the same time, the shield electrode 12 and the first sensor electrodes 11 a and 11 b are connected to the shield drive circuit 24.

  Therefore, in this operation 2, the capacitances of the detection objects A and B are converted into CV by the first and second auxiliary electrodes 13a to 13c and the second sensor electrode 11c as shown in FIG. It is detected by the circuit 21.

  As shown in FIG. 4A, the detection object A is far from the first and second auxiliary electrodes 13a to 13c connected to the positive input terminal P of the CV conversion circuit 21, so that these It can be said that the coupling with the auxiliary electrodes 13a to 13c by the electric lines of force F2 is weak. The second sensor electrode 11c connected to the negative input terminal N of the CV conversion circuit 21 is close to the detection target A, and the first sensor electrodes 11a and 11b connected to the shield drive circuit 24 are also detection targets. It can be said that it is close to thing A.

  For this reason, the coupling of the sensor electrodes 11a to 11c and the detection target A by the electric force lines F1 is stronger than the electric force lines F2, and the capacitance detected by the CV conversion circuit 21 is that of the operation 1. Smaller than when.

  Next, as shown in FIG. 4B, the detection object B existing on the upper outside of the sensor unit 10 with respect to the detection object A is connected to the positive input terminal P of the CV conversion circuit 21. Since it can be said that it is close to the 1st and 2nd auxiliary electrodes 13a-13c, it can be said that the coupling | bonding by these electric lines of force F2 with these auxiliary electrodes 13a-13c is strong. Further, the second sensor electrode 11c connected to the negative input terminal N of the CV conversion circuit 21 is far from the detection target B, and the first sensor electrodes 11a and 11b connected to the shield drive circuit 24 are also detection targets. It can be said that it is far from the object B.

  For this reason, the coupling between the sensor electrodes 11a to 11c and the detection object F1 is weaker than that of the electric force line F2, and the capacitance detected by the CV conversion circuit 21 is larger than that of the detection object A. Become. Therefore, in the case of this operation 2, it is possible to distinguish the detection objects A and B, and the CPU 23 stores the second capacitance value C2 by the output from the CV conversion circuit 21 at this time. .

  In addition, as shown in FIG. 5, in the case of the detection target B ′ closer to the sensor unit 10 than the detection target B, compared to the detection target B shown in FIG. The coupling between the first and second auxiliary electrodes 13a to 13c and the detection object B ′ by the electric lines of force F2 greatly increases. Therefore, if the increase in the coupling due to the electric lines of force F1 between the first and second sensor electrodes 11a to 11c and the detection target B ′ is small, the detection target A and the detection target B ′ shown in FIG. The output from the CV conversion circuit 21 is the same as that in the operation 1, and is almost the same as that in the operation 1.

  In the capacitive proximity sensor 100 according to the present embodiment, the following operation is further performed. First, the first capacitance value C1 and the second capacitance value C2 stored by the CPU 23 are compared. For example, in the case of the operation 1 described above, the detection objects A and B are at substantially the same distance from the first sensor electrodes 11a and 11b, but are connected to the positive input terminal P of the CV conversion circuit 21. The detection value output from the detection object A closer to the first and second sensor electrodes 11a to 11c becomes larger. In addition, since the second auxiliary electrode 13c connected to the negative input terminal N of the CV conversion circuit 21 is closer to the detection target B than the detection target A, the discrimination effect of these targets is further enhanced.

  Next, in the case of the operation 2 described above, since the first and second auxiliary electrodes 13a to 13c are connected to the positive input terminal P of the CV conversion circuit 21, the detection object B is detected. The value increases and the detection object A decreases. Further, since the second sensor electrode 11c connected to the negative input terminal N of the CV conversion circuit 21 is closer to the detection object A than the detection object B, the discrimination effect of these objects is further enhanced.

  As described above, the detection value of the detection object B ′ is substantially the same even when the operation 1 is the operation 2, and the detection object A has the first capacitance value. It can be said that the second capacitance value C2 decreases with respect to C1. Therefore, if the detection target is within the detection range of the sensor unit 10, the first capacitance value C1 is large and the second capacitance value C2 is small, and if it is outside the detection range, it is within the detection range. It has been found that the ratio of the first capacitance value C1 to the second capacitance value C2 decreases compared to the case.

  This means that by comparing the second capacitance value C2 with respect to the first capacitance value C1, it is possible to calculate how much the detection target exists outside the center of the sensor unit 10. It shows that it is possible. Therefore, the capacitive proximity sensor 100 of this example compares this comparison value (calculated value) with a predetermined threshold value, and whether the detection target is within the detection range based on the comparison result, It is configured to be able to determine whether it is outside the detection range, and the directivity can be improved.

  According to the proximity detection method with improved directivity according to the present invention, for example, the following proximity detection processing is performed. FIG. 6 is a flowchart showing an example of a proximity detection processing procedure by the proximity detection method according to the embodiment of the present invention. As shown in FIG. 6, first, as described above, the changeover switches SW1 to SW4 are switched to the 1 side to detect the first capacitance value C1, and the changeover switches SW1 to SW4 are switched to the 2 side to set the second capacitance. Is detected (step S101).

  Next, the detected first capacitance value C1 and the second capacitance value C2 are compared to calculate a comparison value (step S102), and the first capacitance value C1 or the second static value is calculated. Based on the capacitance value C2, it is determined whether or not the detection object is close (step S103). Whether the comparison value between the first capacitance value C1 and the second capacitance value C2 is, for example, not less than a preset threshold value (or less than the threshold value or less than the threshold value). It is determined whether or not (step S106).

  It is determined that the detection target is close (Y in step S103), and it is determined that the comparison value between the first capacitance value C1 and the second capacitance value C2 is greater than or equal to the threshold value. If it is detected (Y in step S106), it is determined that the detection target is detected (step S107). On the other hand, when it is determined that the detection target is not close (N in Step S103), the comparison value between the first capacitance value C1 and the second capacitance value C2 is not equal to or greater than the threshold value. Is determined (N in step S106), it is determined that the detection target is not detected (step S104).

  Then, after determining the detection or non-detection of the detection target (after step S107 or step S104), it is determined whether or not to end the process (step S105), and when it is determined to end the process (step S105). Y) ends the series of proximity detection processing according to this flowchart. If it is determined not to end the process (N in step S105), the process proceeds to step S101 and the subsequent processes are repeated.

  Here, specifically, for example, when the first capacitance value C1 is larger than an arbitrary threshold value Th1, it can be determined that the detection target has approached the first and second sensor electrodes 11a to 11c. (Step S103).

  At this time, the comparison value α = (a × C1) − (b × C2) or the comparison value β = d × (C1 / C2) is calculated by a calculation formula (a, b, d are predetermined coefficients). When the comparison value α or the comparison value β is smaller than a predetermined threshold value Th2, it is outside the detection range of the sensor unit 10, so it is determined as non-detection, and when it is larger, it is within the detection range of the sensor unit 10. Therefore, it is set so that it can be detected and determined (step S106).

  Thereby, even when the detection target is close (Y in Step S103), the process proceeds to Step S106 and the comparison value is smaller than the arbitrary threshold value Th2 (N in Step S106). Is recognized that the detection target is outside the detection range, and it is determined that the detection target is not detected (step S104).

  Further, only when the detection object is close (Y in step S103) and the comparison value is equal to or larger than an arbitrary threshold Th2 (Y in step S106), the detection object is determined to be detected. (Step S107). If it is determined in step S107 that the detection target is detected, for example, the CPU 23 outputs a detection signal or the first and second sensor electrodes 11a of the detection target based on the first capacitance value C1. A signal indicating a proximity distance to ˜11c (a signal corresponding to the distance to these electrodes 11a to 11c) may be output.

  In addition, each element such as the above-described comparison values α, β, coefficients a, b, d and threshold values Th1, Th2 and a calculation formula for the comparison values α, β is the sensor shape of the capacitive proximity sensor 100. Because it varies depending on factors such as the surrounding environment of the installation and the type of target object to be detected, an experiment is conducted when these factors are determined, and a value is obtained while taking the profile, and a comparison value is obtained from this value. And the calculation formula should be set sequentially.

  Thus, according to the configuration of the capacitive proximity sensor 100 of this example, the directivity can be improved when the threshold Th2 is large, and the directivity can be decreased when the threshold Th2 is small. If the threshold value Th2 is appropriately changed, the directivity of the sensor unit 10 can be arbitrarily set.

  In this capacitive proximity sensor 100, the second sensor electrode 11 c connected to the negative input terminal N of the CV conversion circuit 21 in the operation 1 described above and the CV conversion in the operation 2. A second auxiliary electrode 13 c connected to the negative input terminal N of the circuit 21 is provided.

  For this reason, since a subtraction component exists in the capacitance value detected by the CV conversion circuit 21 during operation, the first and second sensor electrodes 11a to 11c and the first and second auxiliary electrodes are present. The directivity of the sensor unit 10 can be arbitrarily changed by changing the shape, size, and arrangement of the electrodes 13a to 13c. That is, it is possible to vary the detection characteristic on the detection surface side of the sensor unit 10 and to detect the detection object based on the capacitance values before and after the variable. Therefore, by combining this with the above-described comparison values and calculation formulas, it becomes possible to set more complex and varied directivity.

  Although it is assumed that the capacitance value detected by the CV conversion circuit 21 of the detection circuit unit 20 is converted into a voltage and processed, it may be converted into data that can be handled electrically or as software. You may use the thing of the structure which can convert an electrostatic capacitance into a pulse width, or can convert it into a digital value directly.

  In addition, the CV conversion circuit 21 performs differential operation, and the second sensor electrode 11c and the second auxiliary electrode 13c are formed, so that the temperature characteristics of the circuit can be offset and a common electrode can be provided without providing a dummy electrode. Mode noise can be reduced.

  Next, another example of the capacitive proximity sensor according to the first embodiment of the present invention will be described. In the capacitive proximity sensor 100 according to the first embodiment described above, whether the output from the CV conversion circuit 21 of the detection circuit unit 20 is the first capacitance value or the second capacitance value. For this reason, the capacitance value detected by the structure around the place where the sensor unit 10 is installed may differ.

  In such a case, it is expected that the comparison result obtained by comparing the first and second capacitance values will change depending on the structure around the place where the sensor unit 10 is installed. In order to avoid such a situation as much as possible, the configuration of the detection circuit unit 20 may be further configured as follows.

  FIG. 7 is a schematic view showing another example of the overall configuration of the capacitive proximity sensor according to the first embodiment of the present invention, and FIG. 8 is a proximity detection processing procedure by the proximity detection method of the capacitive proximity sensor. FIG. 9 is a schematic diagram showing still another example of the overall configuration of the capacitance proximity sensor. In the following description, parts that are the same as those already described are denoted by the same reference numerals, description thereof is omitted, and parts not particularly related to the present invention may not be specified.

  As shown in FIG. 7, in the detection circuit unit 20A of this example, in addition to the CV conversion circuit 21 and the shield drive circuit 24 described above, a determination circuit 25 including, for example, a CPU and a detection target such as a human body are included. An initial capacitance storage device 26 that stores an electrostatic capacitance value when not approaching the sensor unit 10 (initial capacitance, the same unless otherwise specified), and a switch control circuit that controls the switching operation of the selector switches SW1 to SW4. 27 and a buffer 28.

  As an outline of the operation of the detection circuit unit 20A configured as described above, for example, an operation 1 and an operation 2 when the detection target is not approaching the sensor unit 10 after the sensor unit 10 is installed at a predetermined installation location. Are detected by switching the change-over switches SW1 to SW4 under the control of the switch control circuit 27, respectively.

  These values are stored in the initial capacity storage device 26, and stored in the initial capacity storage device 26 from the first and second electrostatic capacitance values in the operations 1 and 2 described above by the determination circuit 25. These initial capacities are subtracted and compared, and it is determined whether or not the detection target is within the detection range based on the comparison result.

  Specifically, the initial capacitance is such that the first and second sensor electrodes 11a to 11c are connected to the positive input terminal P of the CV conversion circuit 21 under the control of the switch control circuit 27, and the first auxiliary electrodes 13a and 13b. Is connected to the shield drive circuit 24, and the first initial capacitance is the one in the above operation 1 when the second auxiliary electrode 13c is connected to the negative input terminal N of the CV conversion circuit 21.

  The initial capacitance is such that the first and second auxiliary electrodes 13a and 13b are connected to the positive input terminal P of the CV conversion circuit 21 under the control of the switch control circuit 27, and the first sensor electrodes 11a and 11b are shield drive circuits. 24 and the second operation electrode when the second sensor electrode 11c is connected to the negative input terminal N of the CV conversion circuit 21 is defined as a second initial capacitance. These first and second initial capacities are stored in the initial capacity storage device 26.

  Then, in the actual operation 1, the determination circuit 25 subtracts the first initial capacitance stored in the initial capacitance storage device 26 from the detected first capacitance value to obtain the first detection value. (Detection value 1). In the actual operation 2, the second detection value (detection value 2) is obtained by subtracting the second initial capacitance stored in the initial capacitance storage device 26 from the detected second capacitance value. And

  That is, as shown in FIG. 8, first, the first detection value and the second detection value as described above are detected (step S201), and the determination circuit 25 compares them to calculate a comparison value ( Step S202). Then, based on the first detection value or the second detection value, it is determined whether or not the detection object is close (step S203), and the comparison value between the first detection value and the second detection value is: For example, it is determined whether or not it is greater than or equal to a predetermined threshold value set in advance (or less than the threshold value or less than the threshold value) (step S206).

  In this process, that is, it is determined whether or not there is a detection target in the detection range based on the first detection value (detection value 1), the second detection value (detection value 2), and the comparison result. When it is determined that the detection object is close (Y in step S203) and the comparison value is determined to be greater than or equal to the threshold (Y in step S206), the detection object is detected (step S206). S207).

  On the other hand, if it is determined that the detection target is close (Y in step S203), but it is determined that the comparison value is not equal to or greater than the threshold value (N in step S206), the detection target is determined as non-detection. (Step S204), for example, a non-detection signal A (for example, a predetermined fixed voltage) that is a disable signal indicating that the detection target does not exist within the detection range of the sensor unit 10 when having directivity is determined. Output as output.

  Further, for example, based on the first or second detection value (or the first or second capacitance value C1, C2), it is determined whether or not the detection target is close (step S203), and the detection target is determined. If it is determined that the object is not in close proximity (N in step S203), the process proceeds to step S204, and the detection target is not detected. For example, the detection target is not within the detection range of the sensor unit 10. The disable signal B shown is output as a determination output.

  After determining whether or not the detection object is detected (after step S207 or step S204), it is determined whether or not to end the process (step S205), and when it is determined to end the process (in step S205) Y) ends the series of proximity detection processing according to this flowchart. If it is determined not to end the process (N in step S205), the process proceeds to step S201 and the subsequent processes are repeated.

  In this way, by setting the output of the determination circuit 25 to, for example, an enable signal or a disable signal according to the determination result, when the detection target is within the detection range of the sensor unit 10, the enable signal is input to the buffer 28, The detection value 1 is output from the buffer 28. When the detection object is not within the detection range of the sensor unit 10, the determination output is an output that is fixed to a predetermined fixed potential such as a ground voltage or a reference voltage as a disable signal.

  In addition, when the detection target is within the detection range, in addition to the detection value 1, the detection value 2 and the first or second capacitance values C1 and C2 may be output. Moreover, these detection value 1, detection value 2, 1st electrostatic capacitance value C1, and 2nd electrostatic capacitance value C2 show the value according to the distance to the sensor electrodes 11a-11c of a detection target. is there.

  Thus, according to the detection circuit unit 20A having the above-described configuration, when the detection target is within the detection range, a detection value or the like corresponding to the distance is output, and when the detection target is not within the detection range, a predetermined fixed voltage or the like is output. Therefore, it is possible to determine whether or not there is a detection target within the detection range, and if so, how long it is. That is, the intensity of directivity of the capacitive proximity sensor 100 can be increased, and the directivity can be set in more detail.

  In addition, as another example of a method for avoiding the influence of the surrounding structure or the like where the sensor unit 10 is installed, these can be held by adjusting the reference voltage as follows. That is, as shown in FIG. 9, the detection circuit unit 20 </ b> B of this example includes a reference voltage adjustment circuit 40 and a subtraction circuit 31 in addition to the CV conversion circuit 21 and the shield drive circuit 24.

  The reference voltage adjustment circuit 40 adjusts the output of the CV conversion circuit 21 to the reference potential during the first and second initial capacitance measurements as described above. Here, the comparator 41, A control circuit 42, a register 43, a D / A converter 44, and an adjustment unit 45 are provided.

  For example, the reference voltage adjustment circuit 40 inputs the output of the CV conversion circuit 21 from the positive input terminal of the comparator 41 and inputs the reference voltage (Reference Voltage: RV) from the negative input terminal, and compares the two. The set value of the register 43 is changed under the control of the control circuit 42 based on the comparison result.

  The output of the register 43 is converted from a digital signal to an analog signal by the D / A converter 44, and then the voltage is adjusted by the adjustment unit 45. The output from the adjustment unit 45 is used to input the CV conversion circuit 21. Adjust. In this way, in the above-described operation 1 when the detection target is not close to the sensor unit 10, the set value of the register 43 is fixed when the output from the CV conversion circuit 21 is closest to the reference potential. Then, the output of the first initial capacity is set as the reference voltage, and the set value (set value 1) at that time is stored.

  At the same time, in the above-described operation 2 when the detection object is not close to the sensor unit 10, the set value of the register 43 is fixed when the output from the CV conversion circuit 21 is closest to the reference potential. The output of the second initial capacity is used as a reference voltage, and the set value (set value 2) at that time is stored.

  In the actual operation 1, the output of the CV conversion circuit 21 when the register 43 is fixed to the set value 1 is input to the positive input terminal of the subtraction circuit 31, for example, and the reference voltage RV is negative. The value is input to the side input terminal, and the output is subtracted by the reference voltage RV to obtain the detected value 1. Further, in the actual operation 2, the output of the CV conversion circuit 21 when the register 43 is fixed to the set value 2 is input to, for example, the plus side input terminal of the subtraction circuit 31, and the reference voltage RV is minus. The value is input to the side input terminal, and the output is subtracted by the reference voltage RV to obtain the detection value 2.

  Thereafter, by comparing the detection value 1 and the detection value 2, it is determined whether or not there is a detection target within the detection range, and if so, how far it is. The input to the CV conversion circuit 21 is adjusted by, for example, increasing or decreasing the input capacitance by applying the voltage of the D / A converter 44 to the adjustment unit 45 including a fixed capacitor connected to the input. Can be realized.

  FIG. 10 is a schematic diagram illustrating an example of the overall configuration of the capacitive proximity sensor according to the second embodiment of the present invention, and FIG. 11 is a schematic diagram illustrating another example of the overall configuration of the capacitive proximity sensor. FIG. 12 is a schematic view showing still another example of the entire configuration of the capacitance proximity sensor. In the capacitive proximity sensor 100A of this example, the connection mode of the sensor electrodes 11a to 11c and the auxiliary electrodes 13a to 13c with the CV conversion circuit 21 by the changeover switches SW1 to SW4 is the electrostatic capacitance according to the first embodiment. This is different from the capacitive proximity sensor 100.

  Specifically, since the selector switches SW1 and SW2 are the same as those in the first embodiment, the description thereof will be omitted. However, when the selector switch SW3 is connected to the second sensor electrode 11c and switched to the 1 side, The second sensor electrode 11c is connected to the shield drive circuit 24. When the second sensor electrode 11c is switched to the second side, it is connected to the negative input terminal N of the CV conversion circuit 21.

  The changeover switch SW4 is connected to the second auxiliary electrode 13c, and when switched to the 1 side, connects the second auxiliary electrode 13c to the negative input terminal N of the CV conversion circuit 21 and is switched to the 2 side. When this occurs, it is connected to the shield drive circuit 24. Thereby, at the time of the operation 1 described above, the second sensor electrode 11c is connected to the positive input terminal P of the CV conversion circuit 21 in the first embodiment, but this is shielded in the second embodiment. Connected to the drive circuit 24.

  Furthermore, during the operation 2 described above, the second auxiliary electrode 13c is connected to the positive input terminal P of the CV conversion circuit 21 in the first embodiment, but this is shield driven in the second embodiment. Connect to circuit 24. As described above, in the capacitive proximity sensor 100A of the second embodiment, the area of the electrode connected to the positive input terminal P of the CV conversion circuit 21 can be reduced compared to the case of the first embodiment. .

  Therefore, in the capacitive proximity sensor 100A according to the second embodiment, since the electrode for the area reduction acts in the same manner as the shield electrode 12, the sensitivity of the entire sensor unit 10 is reduced. Similar to the capacitive proximity sensor 100, the threshold values Th1, Th2 and the like can be appropriately changed to arbitrarily set the directivity of the sensor unit 10.

  In addition, the sensor part 10 and the detection circuit part 20 may be in the following connection states by the changeover switches SW1 to SW4 described above. That is, for example, in the above-described operation 1, the first sensor electrodes 11a and 11b are connected to the positive input terminal P of the CV conversion circuit 21, and the second auxiliary electrode 13c is connected to the negative input terminal N. The shield electrode 12, the second sensor electrode 11c, and the first auxiliary electrodes 13a and 13b are connected to the shield drive circuit 24. In the operation 2 described above, the first and second auxiliary electrodes 13a to 13c are connected to the positive input terminal P of the CV conversion circuit 21, and the second sensor electrode 11c is connected to the negative input terminal N. Thus, the shield electrode 12 and the first sensor electrodes 11 a and 11 b are connected to the shield drive circuit 24. Then, based on the comparison result obtained by such a connection state, it may be similarly determined whether the detection target is within the detection range or outside the detection range.

  Further, for example, during the operation 1, the first and second sensor electrodes 11a to 11c are connected to the positive input terminal P of the CV conversion circuit 21, and the second auxiliary electrode 13c is connected to the negative input terminal N. The shield electrode 12 and the first auxiliary electrodes 13a and 13b are connected to the shield drive circuit 24. In operation 2, the first auxiliary electrodes 13a and 13b are connected to the positive input terminal P of the CV conversion circuit 21, the second sensor electrode 11c is connected to the negative input terminal N, and the shield electrode 12 The first sensor electrodes 11 a and 11 b and the second auxiliary electrode 13 c are connected to the shield drive circuit 24. Such a determination can also be made by such a connection state.

  In addition, the directivity of the sensor unit 10 can be arbitrarily changed by changing the shape, size, and arrangement of the first and second sensor electrodes 11a to 11c and the first and second auxiliary electrodes 13a to 13c. Can be combined with the above-described comparison values and calculation formulas to set more complex and varied directivity.

  Also in the capacitive proximity sensor 100A according to the second embodiment, as shown in FIG. 11, the detection circuit unit 20A includes a determination circuit 25 or the like, or the detection circuit as shown in FIG. Even when a configuration including the reference voltage adjustment circuit 40 or the like is employed as the unit 20B, the same operations and effects as those of the capacitive proximity sensor 100 according to the first embodiment can be realized.

DESCRIPTION OF SYMBOLS 10 Sensor part 11 Sensor electrode 11a 1st sensor electrode 11b 1st sensor electrode 11c 2nd sensor electrode 12 Shield electrode 13a 1st auxiliary electrode 13b 1st auxiliary electrode 13c 2nd auxiliary electrode 20 Detection circuit part 20A Detection circuit part 20B Detection circuit Unit 21 CV conversion circuit 22 A / D converter 23 CPU
24 Shield Drive Circuit 25 Judgment Circuit 26 Initial Capacity Storage Device 27 Switch Control Circuit 31 Subtraction Circuit 40 Reference Voltage Adjustment Circuit 41 Comparator 42 Control Circuit 43 Register 44 D / A Converter 100 Capacitive Proximity Sensor 100A Capacitive Proximity Proximity Sensor

Claims (18)

A first sensor electrode;
A second sensor electrode provided in the vicinity of the first sensor electrode;
A first auxiliary electrode provided in the vicinity of the first and second sensor electrodes;
A second auxiliary electrode provided in the vicinity of the first auxiliary electrode;
A positive input terminal and a negative input terminal are provided, and a capacitance value that is a difference between a capacitance of an electrode connected to the positive input terminal and a capacitance of an electrode connected to the negative input terminal is detected. A capacitance detection circuit;
A shield drive circuit for applying an electric potential to the electrode equivalent to each input terminal of the capacitance detection circuit;
A first connection state in which at least the first sensor electrode is connected to the positive input terminal, the first auxiliary electrode is connected to the shield drive circuit, and the second auxiliary electrode is connected to the negative input terminal; A second connection state in which at least the first auxiliary electrode is connected to the positive input terminal, the first sensor electrode is connected to the shield drive circuit, and the second sensor electrode is connected to the negative input terminal. A changeable switch,
The first capacitance value from the capacitance detection circuit in the first connection state was compared with the second capacitance value from the capacitance detection circuit in the second connection state. A capacitance type comprising a comparison value and a comparison determination means for determining whether or not the detection object is within the range of the detection region based on the comparison value and the first or second capacitance value Proximity sensor. In the first connection state, the second sensor electrode is further connected to the positive input terminal, and in the second connection state, the second auxiliary electrode is further connected to the positive input terminal. The capacitive proximity sensor according to claim 1. The first and second sensor electrodes and the first and second auxiliary electrodes are disposed on the back side opposite to the respective detection surfaces in a state of being insulated from the sensor electrodes and the auxiliary electrodes, The capacitive proximity sensor according to claim 1, further comprising a shield electrode that shields detection on the back side of the electrode. The said 1st sensor electrode, the said 2nd sensor electrode, the said 1st auxiliary electrode, and the said 2nd auxiliary electrode are arrange | positioned in the state mutually insulated on the same plane, respectively. 4. The capacitive proximity sensor according to any one of 3 above. 5. The capacitive proximity sensor according to claim 1, wherein the first sensor electrode is disposed so as to surround the second sensor electrode from an outer peripheral side thereof. The first sensor electrode is formed in a shape having a rectangular portion formed in a rectangular shape and a square shape formed in a square shape surrounding the rectangular portion, and the first sensor electrode is formed in a square shape. The capacitive proximity sensor according to any one of claims 1 to 4, wherein the second sensor electrode is disposed so as to be sandwiched between the rectangular portion and the square-shaped portion. The capacitance type proximity sensor according to claim 1, wherein the first auxiliary electrode is disposed so as to surround the second auxiliary electrode from the outer peripheral side. The first auxiliary electrode is formed in a shape having a plurality of B-shaped portions formed in a B shape having different sizes, and the second auxiliary electrode formed in a B shape is connected to the plurality of B-shaped portions. The capacitive proximity sensor according to claim 1, wherein the capacitive proximity sensor is disposed so as to be sandwiched between the character portions. The capacitive proximity sensor according to claim 1, wherein the first and second auxiliary electrodes are arranged so as to surround the first and second sensor electrodes. The static electricity according to any one of claims 1 to 9, wherein the first sensor electrode, the second sensor electrode, the first auxiliary electrode, and the second auxiliary electrode are arranged concentrically. Capacitive proximity sensor. The comparison determination unit calculates a comparison value by multiplying a value obtained by dividing the first capacitance value by the second capacitance value by a predetermined coefficient, and the comparison value is set in advance. The capacitance proximity sensor according to any one of claims 1 to 10, wherein it is determined whether or not there is an object to be detected within a detection area depending on whether or not the threshold value is exceeded. . The capacitance detection circuit includes a first initial capacitance that is an initial capacitance of the first capacitance value when there is no detection target within the detection area, and a detection target within the detection area. A second initial capacitance that is an initial capacitance of the second capacitance value when there is no
The comparison determination means includes a first detection value obtained by subtracting the first initial capacitance from the first capacitance value, and a first detection value obtained by subtracting the second initial capacitance from the second capacitance value. It is determined whether a detection target exists in the range of a detection area based on the comparison value which compared two detection values, and the 1st or 2nd detection value. 11. The capacitive proximity sensor according to any one of 11 above. Reference voltage adjusting means for setting the output of the capacitance detection circuit to a reference voltage
The capacitance detection circuit is configured to adjust a first initial capacitance, which is an initial capacitance of the first capacitance value when there is no detection target within a detection area, to the reference voltage. And a second setting value for adjusting the second initial capacitance, which is the initial capacitance of the second capacitance value when there is no detection object within the detection area, to the reference voltage Are obtained from the reference voltage adjusting means, and a first capacitance value adjusted by the first set value and a second capacitance value adjusted by the second set value are output. Configured to
The comparison determination means sets the first detection value obtained by subtracting the reference voltage from the first capacitance value adjusted by the first setting value, and the first adjustment value adjusted by the second setting value. Based on the comparison value obtained by subtracting the reference voltage from the capacitance value of 2 as the second detection value and comparing the two, and the first or second detection value, the detection target is within the detection region. The capacitance type proximity sensor according to any one of claims 1 to 11, wherein the capacitance type proximity sensor is determined. When the comparison determination unit determines that the detection target is within the detection region, the first capacitance value, the second capacitance value, the first detection value, and the Based on one of the second detection values, a signal corresponding to the distance to the at least one of the first and second sensor electrodes of the detection object is output,
The capacitive proximity sensor according to claim 12 or 13, wherein when it is determined that there is no detection target within the detection area, the output is set to a predetermined fixed voltage. The capacitive proximity sensor according to claim 14, wherein the predetermined fixed voltage is a ground voltage or a reference voltage. A first auxiliary electrode having a positive input terminal and a negative input terminal; a first sensor electrode; a second sensor electrode provided in the vicinity of the first sensor electrode; and a first auxiliary provided in the vicinity of the first and second sensor electrodes. Of the electrode and the second auxiliary electrode provided in the vicinity of the first auxiliary electrode, the difference between the capacitance of the electrode connected to the positive input terminal and the capacitance of the electrode connected to the negative input terminal A capacitance detection circuit for detecting a capacitance value and a changeover switch for switching a connection state between these electrodes and each input terminal, and whether or not a detection target is within the detection area. A proximity detection method of detecting the proximity of the detection object by a capacitive proximity sensor capable of being determined,
Switching the connection state of the electrodes to the positive input terminal and the negative input terminal by the changeover switch, and varying the detection characteristics on the detection surface side;
Detecting the capacitance values before and after the detection characteristics are varied by the capacitance detection circuit, respectively, and obtaining the first and second capacitance values;
Based on the comparison value between the first capacitance value and the second capacitance value and the first or second capacitance value, whether or not there is a detection target within the detection area A proximity detecting method comprising: a step of determining whether or not. When there is a detection object within the range of the detection region, a distance to at least one of the first and second sensor electrodes of the detection object is further determined based on the first or second capacitance value. The proximity detection method according to claim 16, wherein the determination is performed. A first auxiliary electrode having a positive input terminal and a negative input terminal; a first sensor electrode; a second sensor electrode provided in the vicinity of the first sensor electrode; and a first auxiliary provided in the vicinity of the first and second sensor electrodes. Of the electrode and the second auxiliary electrode provided in the vicinity of the first auxiliary electrode, the difference between the capacitance of the electrode connected to the positive input terminal and the capacitance of the electrode connected to the negative input terminal It is determined whether there is a detection object within the detection area by a capacitance detection circuit that detects the capacitance value and a changeover switch that switches the connection state between these electrodes and each input terminal. An electrode structure of a capacitive proximity sensor that is possible,
A function of detecting a capacitance connected to the positive input terminal, formed in a shape having a rectangular portion formed in a rectangular shape and a square shape formed in a square shape surrounding the rectangular portion; A first sensor electrode having a function of shielding the detection;
A function of detecting a capacitance by being connected to the positive input terminal or the negative input terminal and being detected between the rectangular part of the first sensor electrode and the rectangular part of the first sensor electrode. A second sensor electrode having a shielding function;
Capacitance formed in a shape having a plurality of square-shaped portions formed in different square shapes having different sizes, provided on the outer peripheral side of the first and second sensor electrodes, and connected to the positive input terminal A first auxiliary electrode having a function of detecting and a function of shielding the detection;
A function of detecting a capacitance by being connected to the positive input terminal or the negative input terminal and shielding the detection, provided between the plurality of square-shaped portions of the first auxiliary electrode. An electrode structure of a capacitive proximity sensor, comprising: a second auxiliary electrode having a function of:

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