JP2010249531A - Raindrop detector and wiper operation controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To constitute with a simple structure and at low cost and detect raindrops adhering to the windshield of a vehicle without impairing the appearance. <P>SOLUTION: A raindrop detector includes: capacitance sensor parts 10, 20 each arranged on an instrument panel 2 and a rear tray 3 of the vehicle 1; and a circuit part 30. Each of the capacitance sensor parts 10, 20 includes a sensor electrode 11, a shield electrode 12 and an auxiliary electrode 13. Using a first capacitance value C1 detected only by the sensor electrode 11 and second capacitance values C2 detected by the sensor electrode 11 and the auxiliary electrode 13, the directivity is set up. Detection ranges Z1, Z2 are formed on the surface of each of the capacitance sensor parts 10, 20, and the raindrops 9 adhering to the windshield and rear glass are detected. A wiper operation controller controls the operations of at least one of a front wiper 51 and a rear wiper 52 based on the detection result from the raindrop detector. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a raindrop detection device and a wiper operation control device that detect raindrops attached to a window glass of a vehicle such as an automobile.

  For example, a water droplet sensor (see, for example, Patent Document 1 (pages 3-7 and 1-17)) is known as a device that detects raindrops attached to a window of a vehicle such as an automobile. This water droplet sensor includes a water droplet detection unit composed of a pair of transparent electrodes and a pair of comb-like patterns alternately arranged between a vehicle outer side glass and an intermediate film of a window shield (window glass) having a laminated glass structure.

  In addition, a conductive film is provided between the vehicle interior glass and the intermediate film to electrically shield the interior of the vehicle, and through holes are provided in the conductive film so that water droplets adhering to the vehicle interior of the window shield are formed through the through holes. Detect through. As a result, the water droplets outside the vehicle can be detected by the pair of transparent electrodes, and the water droplets inside the vehicle can also be detected, and water droplets inside and outside the vehicle are detected.

  Further, a raindrop sensor (for example, see Patent Document 2 (page 2-7, FIG. 1-11)) is also known. When this raindrop sensor detects raindrops based on a change in capacitance between the electrodes, the first and second electrodes are attached to the back surface of the dielectric formed in a plate shape at a predetermined interval from each other. Has been.

JP-A-6-273362 JP 62-175653 A

  However, the water droplet sensor disclosed in Patent Document 1 described above has a structure in which the transparent electrode is embedded in the window shield, so that the structure is complicated and the cost is high. In addition, the raindrop sensor disclosed in Patent Document 2 described above requires a dielectric and has a structure that can be attached to the hood of an automobile. Therefore, the raindrop sensor is similarly costly and may damage the appearance of the hood design and the like. There is a problem that there is.

  The present invention eliminates the problems caused by the prior art described above, and can be configured with a simple structure at low cost, and can detect raindrops attached to a window glass of a vehicle such as an automobile without deteriorating the appearance. And it aims at providing a wiper operation control device.

  In order to solve the above-described problems and achieve the object, a raindrop detection device according to the present invention includes a window on at least one of an upper surface portion of a vehicle instrument panel, an upper surface portion of a rear tray, and a window frame edge portion of a rear gate. A sensor electrode arranged so that a detection surface exists toward the glass, an auxiliary electrode provided in the vicinity of the sensor electrode, and at least the sensor electrode is connected, and static electricity based on the capacitance from the connected electrode. A detection circuit that detects a capacitance value, a first connection state in which the auxiliary electrode is not connected to the detection circuit, and a second connection state in which the auxiliary electrode is connected to the detection circuit can be selectively switched. A changeover switch, a first capacitance value from the detection circuit in the first connection state, and a second static value from the detection circuit in the second connection state. Raindrop determination for determining whether or not raindrops attached to the window glass are within a detection range on the sensor electrode based on a comparison value comparing with a capacitance value and the first or second capacitance value Means.

  The change-over switch is configured to be able to open, connect to the ground, or to a predetermined potential, for example, when the auxiliary switch is in the first connection state.

  The shield switch further includes a shield drive circuit that applies a potential equivalent to the sensor electrode to the auxiliary electrode, and the changeover switch is configured to be able to connect the auxiliary electrode to the shield drive circuit, for example, in the first connection state. ing.

  The raindrop detection device according to the present invention is arranged such that at least one of the upper surface portion of the instrument panel of the vehicle, the upper surface portion of the rear tray, and the window frame edge portion of the rear gate has a detection surface facing the window glass. A sensor electrode, an auxiliary electrode provided in the vicinity of the sensor electrode, a detection circuit for detecting a capacitance value based on a capacitance from the sensor electrode, and the auxiliary electrode equivalent to the sensor electrode. A shield driving circuit for applying a potential; a first connection state in which the auxiliary electrode is connected to the shield driving circuit; and a second connection state in which the auxiliary electrode is open, grounded or connected to a predetermined potential. A changeable switch, a first capacitance value from the detection circuit in the first connection state, and the detection circuit in the second connection state Whether raindrops adhering to the window glass are within the detection range on the sensor electrode based on the comparison value compared with the second capacitance value and the first or second capacitance value. Raindrop determining means for determining whether or not.

  Furthermore, the raindrop detection apparatus according to the present invention is arranged such that a detection surface exists toward the window glass on at least one of the upper surface portion of the instrument panel of the vehicle, the upper surface portion of the rear tray, and the window frame edge portion of the rear gate. Sensor electrode, an auxiliary electrode provided in the vicinity of the sensor electrode, a detection circuit for detecting a capacitance value based on a capacitance from the connected electrode, and connecting the sensor electrode to the detection circuit A first changeover switch capable of selectively switching between a first connection state to be connected and a second connection state in which the sensor electrode is not connected to the detection circuit; and when the sensor electrode is in the first connection state The auxiliary electrode is not connected to the detection circuit, and can be switched so that the auxiliary electrode is connected to the detection circuit when the first changeover switch is in the second connection state. Second switching switch, a first capacitance value from the detection circuit in the case of the first connection state, and a second capacitance from the detection circuit in the case of the second connection state Raindrop determining means for determining whether or not raindrops attached to the window glass are within a detection range on the sensor electrode based on a comparison value obtained by comparing with a value and the first or second capacitance value It is characterized by comprising.

  The first changeover switch is configured to be able to open, connect to the ground or a predetermined potential of the sensor electrode in the second connection state, for example, and the second changeover switch is, for example, in the first connection state. Sometimes, the auxiliary electrode is open, grounded, or connectable to a predetermined potential.

  A shield driving circuit that applies a potential equivalent to the sensor electrode to the auxiliary electrode or a potential equivalent to the auxiliary electrode to the sensor electrode; and the first changeover switch is, for example, in the second connection state Sometimes the sensor electrode is configured to be connectable to the shield drive circuit, and the second changeover switch is configured to be able to connect the auxiliary electrode to the shield drive circuit, for example, in the first connection state. .

  A shield driving circuit for applying a potential equivalent to that of the sensor electrode to the auxiliary electrode is further provided, and the first changeover switch opens the auxiliary electrode, for example, is connected to ground or a predetermined potential in the second connection state. The second changeover switch is configured to be able to connect the auxiliary electrode to the shield drive circuit in the first connection state, for example.

  A shield driving circuit for applying a potential equivalent to that of the auxiliary electrode to the sensor electrode is further provided, and the first changeover switch is configured to be able to connect the auxiliary electrode to the shield driving circuit in the second connection state, for example. For example, the second changeover switch is configured to be able to open the auxiliary electrode, connect to the ground, or to a predetermined potential in the first connection state.

  The auxiliary electrode is disposed, for example, so as to surround the sensor electrode.

  A wiper operation control device according to the present invention includes a raindrop detection device according to the above invention, and an operation control means for controlling the operation of the wiper device mounted on the vehicle based on a detection result detected by the raindrop detection device. It is provided with.

  According to the present invention, it is possible to provide a raindrop detection device and a wiper operation control device that can be configured with a simple structure at low cost and can detect raindrops attached to a window glass of a vehicle such as an automobile without impairing the appearance. it can.

It is explanatory drawing which shows the example of the whole structure of the wiper operation control apparatus provided with the raindrop detection apparatus concerning one Embodiment of this invention. It is explanatory drawing which shows the example of the whole structure of the wiper operation control apparatus provided with the raindrop detection apparatus. It is explanatory drawing which shows the example of the whole structure of the electrostatic capacitance sensor part and circuit part of the raindrop detection apparatus. It is explanatory drawing for demonstrating the operation | movement concept at the time of the detection operation | movement of the raindrop detection apparatus. It is explanatory drawing for demonstrating the relationship between the detection target object at the time of the detection operation of the raindrop detection apparatus, and an electric force line. It is explanatory drawing for demonstrating the operation | movement concept at the time of the detection operation | movement of the raindrop detection apparatus. It is a flowchart which shows the example of the operation control processing procedure of the wiper by the wiper operation control apparatus. It is explanatory drawing which shows the other example of the whole structure of the electrostatic capacitance sensor part and circuit part of the raindrop detection apparatus. It is explanatory drawing which shows the example of the whole structure of the electrostatic capacitance sensor part and circuit part of the raindrop detection apparatus concerning other embodiment of this invention. It is a flowchart which shows the example of the operation control processing procedure of the wiper by the wiper operation control apparatus provided with the raindrop detection apparatus. It is explanatory drawing which shows the other example of the whole structure of the electrostatic capacitance sensor part and circuit part of the raindrop detection apparatus. It is explanatory drawing which shows the example of the whole structure of the electrostatic capacitance sensor part and circuit part of the raindrop detection apparatus concerning further another embodiment of this invention. It is explanatory drawing for demonstrating the operation | movement concept at the time of the detection operation | movement of the raindrop detection apparatus. It is explanatory drawing for demonstrating the relationship between the detection target object and electric force line at the time of 1st detection operation | movement of the raindrop detection apparatus. It is explanatory drawing for demonstrating the relationship between the detection target object and electric force line at the time of 1st detection operation | movement of the raindrop detection apparatus. It is explanatory drawing for demonstrating the relationship between the detection target object and electric force line at the time of 1st detection operation | movement of the raindrop detection apparatus. It is explanatory drawing for demonstrating the relationship between the detection target object and electric force line at the time of the 2nd detection operation of the raindrop detection apparatus. It is explanatory drawing for demonstrating the relationship between the detection target object and electric force line at the time of the 2nd detection operation of the raindrop detection apparatus. It is explanatory drawing for demonstrating the relationship between the detection target object and electric force line at the time of the 2nd detection operation of the raindrop detection apparatus. It is explanatory drawing which shows the example of the whole structure of the electrostatic capacitance sensor part and circuit part of the raindrop detection apparatus concerning further another embodiment of this invention. It is explanatory drawing which shows the other example of the whole structure of the electrostatic capacitance sensor part and circuit part of the raindrop detection apparatus.

  Exemplary embodiments of a raindrop detection device and a wiper operation control device according to the present invention will be described below with reference to the accompanying drawings.

  1 and 2 are explanatory diagrams showing an example of the overall configuration of a wiper operation control device provided with a raindrop detection device according to an embodiment of the present invention, and FIG. 3 is a capacitance sensor section and a circuit of the raindrop detection device. It is explanatory drawing which shows the example of the whole structure of a part. As shown in FIG. 1, the raindrop detection apparatus according to the present embodiment includes a front capacitance sensor unit 10 provided on an upper surface portion of an instrument panel 2 of a sedan type vehicle 1, and a rear tray 3 of the vehicle 1, for example. And a rear capacitance sensor unit 20 provided on the upper surface.

  The front capacitance sensor unit 10 detects raindrops 9 attached to the outer surface side of the front window glass (front glass) of the vehicle 1. The rear electrostatic capacitance sensor unit 20 detects raindrops 9 attached to the outer surface side of the rear window glass (rear glass) of the vehicle 1. The capacitance sensor units 10 and 20 are arranged near the center of the instrument panel 2 and the rear tray 3 in the width direction of the vehicle 1 and near the end of the width direction, and the detection range Z1 of the raindrop 9 toward the windshield and the rear glass, respectively. , Z2 are formed.

  Further, the raindrop detection device detects that the raindrops 9 attached to the windshield and the rear glass are within the detection ranges Z1 and Z2 on the capacitance sensor units 10 and 20 based on the outputs from the capacitance sensor units 10 and 20. A circuit unit 30 for determining whether or not there is provided. The wiper operation control device includes a wiper operation control unit 50 composed of a CPU or the like. The wiper operation control unit 50 uses the wiper operation control unit 50 based on the output (determination result) from the circuit unit 30 of the raindrop detection device. Drive motors (not shown) of the wiper 51 and the rear wiper 52 are driven to control at least one operation of each of the wipers 51 and 52.

  As shown in FIG. 2, in the hatchback type vehicle 1 </ b> A, the front capacitance sensor unit 10 is similarly arranged on the upper surface portion of the instrument panel 2, but the rear capacitance sensor unit 20 is a rear gate. 4 is arranged so as to form a detection range Z2 of raindrops 9 toward the rear glass at the edge of the window frame.

  In addition, each of the capacitance sensor units 10 and 20 may be disposed on the vehicle 1 or 1A, or may be disposed on the instrument panel 2, the rear tray 3, or the rear gate 4, and the raindrop 9 is preferable. However, the arrangement is not limited to this as long as it can be detected.

  As shown in FIG. 3, each of the capacitance sensor units 10 and 20 is configured such that detection ranges Z1 and Z2 exist in the detection area on the detection surface side facing the windshield and the rear glass, and is formed in a rectangular flat plate shape. The sensor electrode 11, the shield electrode 12 formed on the back side of the sensor electrode 11, and the auxiliary electrode 13 formed on the same plane as the sensor electrode 11 so as to surround the sensor electrode 11. And each of them.

  The sensor electrode 11 and the auxiliary electrode 13 are disposed so as to be insulated from each other. The shield electrode 12 is preferably larger than the sensor electrode 11 in order to reduce the sensor sensitivity on the back side.

  The sensor electrode 11 detects an object (raindrop 9) in the detection range Z1, Z2 of the detection area on the detection surface side. The shield electrode 12 shields the sensor electrode 11 from being detected on the back side. The auxiliary electrode 13 is for changing the equicapacitance line (surface) on the detection surface side of the sensor electrode 11 so that each of the capacitance sensor units 10 and 20 has directivity. In addition, the shield electrode 12 may be provided in the outer peripheral side of the auxiliary electrode 13 together with the aspect mentioned above, for example.

  The circuit unit 30 is connected to each of the capacitance sensor units 10 and 20, and includes, for example, a CV conversion circuit 21 directly connected to the sensor electrode 11, an A / D converter 22, and a CPU 23. ing. Here, a shield drive circuit 12 is further provided, and a changeover switch SW for switching the connection of the auxiliary electrode 13 between the CV conversion circuit 21 and the shield drive circuit 24 is provided.

  The CV conversion circuit 21 converts a capacitance detected by the sensor electrode 11 or the sensor electrode 11 and the auxiliary electrode 13 into a 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 CPU 23 controls the raindrop detection apparatus as a whole, controls the changeover switch SW, determines the detection (presence / absence) of the detection target (raindrop 9) in the detection ranges Z1 and Z2 of the detection area, and the determination result. Or a signal related to the wiper operation control unit 50 is output. The shield drive circuit 24 drives, for example, the shield electrode 12 and the auxiliary electrode 13 to the same potential as the sensor electrode 11.

  The circuit unit 30 includes a storage unit (not shown) such as a RAM used as a temporary storage area of the CPU 23 and a data storage ROM. Moreover, each electrostatic capacitance sensor part 10 and 20 is formed on the board | substrate which is not shown in figure, for example. As this board | substrate, any board | substrate of a flexible printed circuit board, a rigid board | substrate, and a rigid flexible board | substrate is employable, for example.

  Furthermore, the circuit unit 30 may be mounted and integrally provided on the same surface side or the back surface side of the substrate on which the capacitance sensor units 10 and 20 are formed. In this case, a plurality of circuit units 30 may be provided so as to correspond to the number of capacitance sensor units 10 and 20.

  The sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13 are substrates 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, a copper alloy, a metal member (conductive material) such as aluminum or iron, an electric wire, or the like patterned on top.

  Note that, depending on the arrangement mode of each of the capacitance sensor units 10 and 20 (for example, when arranged on the surface of the instrument panel 2 or the like), it is necessary to arrange the capacitance sensor units 10 and 20 so that they are not conspicuous with respect to the vehicle 1 or 1A. There is a case. In such a case, the substrate may be formed of a transparent panel or film, and the electrodes 11 to 13 may be transparent electrodes.

  The transparent electrode can be composed of, for example, tin-doped indium oxide (ITO) or a conductive polymer. As the conductive polymer, for example, PEDOT / PSS (polyethylene dioxythiophene / polystyrene sulfonic acid), PEDOT / TsO (polyethylene dioxythiophene / toluene sulfonate), or the like can be used.

  Next, the detection operation of the detection target (raindrop 9) of the raindrop detection apparatus configured as described above will be described. First, an operation (operation 1) when the changeover switch SW is connected to the shield drive circuit 24 side under the control of the CPU 23 will be described. In the case of this operation 1, the connection state between the sensor electrode 11, the shield electrode 12, the auxiliary electrode 13, and the circuit unit 30 of each of the capacitance sensor units 10 and 20 is as shown in FIG.

  That is, only the sensor electrode 11 is connected to the CV conversion circuit 21, and the shield electrode 12 and the auxiliary electrode 13 are connected to the shield drive circuit 24. The capacitance C with B is detected by the CV conversion circuit 21. At this time, the back surface side of the sensor electrode 11 is covered with the shield electrode 12 connected to the shield drive circuit 24. For this reason, the sensor sensitivity on the back surface side of the sensor electrode 11 is almost equal, and this is also the case with the operation 2 described later.

  Further, both detection objects A and B are at substantially the same distance from the sensor electrode 11. However, due to the influence of the auxiliary electrode 13 connected to the shield drive circuit 24, the above-described equal capacitance line (surface) M is in a state as shown in FIG. Lower than the sensor sensitivity to.

  In this case, as shown in FIG. 5A, the electric lines of force P1 from the sensor electrode 11 with respect to the detection object A existing near the center of the sensor electrode 11 are the electric lines of force P2 from the auxiliary electrode 13 (shield). ) Is small. However, as shown in FIG. 5B, the electric lines of force P <b> 1 from the sensor electrode 11 to the detection target B existing outside the sensor electrode 11 are the electric lines of force P <b> 2 (shield) from the auxiliary electrode 13. It can be said that it is easily affected.

  For this reason, in the operation 1, both the detection objects A and B exist at the same distance from the sensor electrode 11, but the capacitance value detected by the CV conversion circuit 21 is the detection object of the detection object A. It becomes larger than the object B. The first capacitance value C1 detected during such operation 1 is stored in the storage unit by the CPU 23.

  In the case of this operation 1, by connecting the auxiliary electrode 13 to the shield drive circuit 24, the sensor at the electrode end (end on the auxiliary electrode 13 side) of the sensor electrode 11 with respect to the sensor sensitivity at the center of the sensor electrode 11 is detected. Sensitivity can be lowered. Thereby, it becomes possible to give each electrostatic capacitance sensor part 10 and 20 slight directivity.

  However, in this operation 1, the sensor sensitivity of the electrode end of the sensor electrode 11 is only slightly reduced. Therefore, for example, the capacitance value of the detection object C (see FIG. 4) which is the raindrop 9 located closer to the sensor electrode 11 than the detection object B shown in FIG. It becomes almost equal to the capacitance value. At this time, the equal capacitance line (surface) M is in a state as shown in FIG. For this reason, the difference between the detection objects A and C cannot be determined, and it must be said that this is a state in which a stronger directivity cannot be provided.

  Next, an operation (operation 2) when the changeover switch SW is connected to the CV conversion circuit 21 side under the control of the CPU 23 will be described. In the case of this operation 2, the connection state between the sensor electrode 11, the shield electrode 12 and the auxiliary electrode 13 of each of the capacitance sensor units 10 and 20 is as shown in FIG.

  That is, since the sensor electrode 11 and the auxiliary electrode 13 are connected to the CV conversion circuit 21, the capacitance between the detection objects A and B is changed by the CV conversion circuit 21 by the sensor electrode 11 and the auxiliary electrode 13. Detected. At this time, as described above, the sensor sensitivity on the back surface side of the sensor electrode 11 is almost equal, but the equivalent capacitance line (surface) M on the detection surface side (front surface side) of the sensor electrode 11 is in the state shown in FIG. Thus, it can be said that there is no directivity in the range of 180 ° on the detection surface side.

  For this reason, in the operation 2, substantially the same capacitance value is detected for both detection objects A and B existing at substantially the same distance from the sensor electrode 11. Then, the second capacitance value C2 detected during such operation 2 is stored in the storage means by the CPU 23 in the same manner as the first capacitance value C1.

  As described above, the operation 1 and the operation 2 described above can vary the equicapacitance line (surface) M on the detection surface side by the sensor electrode 11. Thus, the first capacitance value C1 detected when there is a slight directivity on the detection surface side of the sensor electrode 11 and the second capacitance detected when there is no directivity on the detection surface side of the sensor electrode 11. Is obtained.

  Thereafter, in the raindrop detection apparatus of this example, the following operation is performed. First, the first capacitance value C1 stored in the storage means by the CPU 23 is compared with the second capacitance value C2. For example, in the case of the operation 2 described above, since the capacitance values detected from both the detection objects A and B are substantially the same value, the detection objects A and B are at an approximately equal distance from the sensor electrode 11. It turns out that there is.

  Next, in the case of the operation 1, since the electrostatic capacitance value of the detection target B is smaller than the detection target A, the detection target B should be outside the detection electrode A with respect to the sensor electrode 11. Becomes clear. Based on these considerations, the CPU 23 compares the second capacitance value C2 with the first capacitance value C1 to determine how much the detection target is outside the central portion of the sensor electrode 11. (That is, whether or not the detection target is within a predetermined range including at least a region facing the detection surface of the sensor electrode 11 (hereinafter, may be abbreviated as “in the detection range”)). ) Can be determined.

  According to the raindrop detection apparatus configured and operated as described above, as shown in FIGS. 1 and 2, for example, the front capacitance disposed on the upper surface portion of the instrument panel 2 by the front capacitance sensor unit 10. It can be determined whether or not there is a raindrop 9 in the detection range Z1 formed on the sensor unit 10 (sensor electrode 11).

  Further, for example, within the detection range Z2 formed by the rear capacitance sensor unit 20 on the rear capacitance sensor unit 20 (sensor electrode 11) disposed on the upper surface of the rear tray 3 or the window frame edge of the rear gate 4. It can be determined whether or not there are raindrops 9 on the surface. These detection ranges Z1 and Z2 are determined by the set directivity. Further, the detected capacitance value when raindrops 9 adhere to the windshield and rear glass can also be determined from the profile.

  For this reason, for example, even if there is an object (such as luggage) outside the detection range Z1, Z2 in the vicinity of the instrument 2 and the rear tray 3 or the rear gate 4, this object is not detected, and the object is detected in the detection range Z1. The detection ranges Z1 and Z2 are determined so that it is possible to accurately determine whether or not there are raindrops 9 in the detection ranges Z1 and Z2 by excluding these as threshold values even if they are within the detection ranges Z2 and Z2. The region is set on the sensor electrode 11.

  Based on the determination result, the wiper operation control unit 50 outputs a control signal for operating the wipers 51 and 52 to the drive motor when, for example, the raindrop 9 is detected. The drive motor immediately operates the wipers 51 and 52 based on the control signal. In this way, each wiper 51, 52 can be automatically operated or stopped in the vehicle 1, 1A.

  Since each of the capacitance sensor units 10 and 20 does not need to be incorporated in the windshield or rear glass as compared with the conventional one, it can be configured with a simple structure at a low cost. Moreover, since it can arrange | position to the instrument panel 2, the rear tray 3, or the rear gate 4, it can implement | achieve, without impairing external appearances, such as a design of the vehicles 1 and 1A. Here, the wiper operation control processing of the wipers 51 and 52 by the wiper operation control device will be described.

  FIG. 7 is a flowchart showing an example of a wiper operation control processing procedure for each of the wipers 51 and 52 by the wiper operation control device including the raindrop detection device. In the following, it is assumed that the same reference numerals are assigned to portions that overlap with the portions that have already been described, and descriptions thereof are omitted. As shown in FIG. 7, first, the wiper operation control device starts the processing of the raindrop detection device triggered by, for example, the ignition switch of the vehicle 1, 1 </ b> A being turned on as an accessory or ON, and then the CPU 23 of the circuit unit 30. With this control, the connection state of the auxiliary electrode 13 by the changeover switch SW is switched to the first and second connection states described above.

  Thus, the capacitance values (first and second capacitance values C1 and C2) are detected in the capacitance sensor units 10 and 20 (step S102), and these are compared to calculate a comparison value ( Step S103).

  Then, based on the first capacitance value C1 or the second capacitance value C2, it is determined whether or not the detection target (raindrop 9) is close to the sensor electrode 11 (step S104). At the same time, it is determined whether or not the calculated comparison value is greater than or equal to a predetermined threshold value set in advance (or less than a predetermined threshold value or less than a predetermined threshold value, for example) (step S105).

  When it is determined that the raindrop 9 is close (Y in step S104) and the comparison value is determined to be equal to or greater than a predetermined threshold (Y in step S105), the raindrop 9 is determined to be detected. (Step S106), a signal related to the determination result is output to the wiper operation control unit 50. The wiper operation control unit 50 operates at least one of the front wiper 51 and the rear wiper 52 in accordance with the capacitance sensor units 10 and 20 that have detected the raindrop 9 among the capacitance sensor units 10 and 20. The wiper operation control is performed (step S107).

  If the operation of each wiper 51, 52 is controlled using the determination result thus determined, the operation of each wiper 51, 52 can be automatically controlled as described above. For this reason, operation control of each wiper 51 and 52 can be performed cheaply with a simple structure.

  On the other hand, when it is determined that the raindrops 9 are not close (N in step S104), or when it is determined that the comparison value is not equal to or greater than the predetermined threshold (N in step S105), the raindrops 9 are not detected. (Step S108) and the operations of the wipers 51 and 52 are not performed. Then, for example, it is determined whether or not the process of the raindrop detection device is to be ended by using the ignition switch of the vehicle 1 or 1A as a trigger (step S109).

  If it is determined that the process is to be terminated (Y in step S109), the series of wiper operation control processes according to this flowchart is terminated. When it is determined that the process is not finished (N in Step S109), the process proceeds to Step S102, and the first and second capacitance values C1 and C2 of the capacitance sensor units 10 and 20 are detected. And the subsequent processing is repeated.

  Here, specifically, for example, in step S104, when the first capacitance value C1 is larger than the predetermined threshold value Th1, it is set so that it can be determined that the raindrop 9 has approached the sensor electrode 11. Keep it. At this time, for example, in step S105, the comparison value α or the comparison value β calculated by a calculation formula such as the comparison value α = (a × C1) − (b × C2) or the comparison value β = d × C1 / C2. Is smaller than an arbitrary threshold value Th2 as a predetermined threshold value set in advance, it is set so that it can be determined that it is outside the detection ranges Z1 and Z2.

  Only when the raindrops 9 are close to each other (Y in step S104) and the comparison value is equal to or greater than the threshold Th2 (Y in step S105), the raindrops 9 are determined to be detected (step S104). S106). Thus, according to the raindrop detection device of the present example, the sensor electrodes 11 on the surfaces of the capacitance sensor units 10 and 20 disposed on the instrument panel 2, the rear tray 3, or the rear gate 4 of the vehicle 1, 1 </ b> A. The proximity of the raindrop 9 to the detection ranges Z1 and Z2 can be detected accurately and reliably.

  Note that the coefficients a, b, and c in the comparison values α and β, the calculation formulas of the comparison values α and β, the values of the threshold values Th1 and Th2, and the like may be as follows. That is, these change depending on factors such as the sensor shape of each of the capacitance sensor units 10 and 20, the surrounding environment of the installation, and the characteristics of the detection target. For this reason, what is necessary is just to set it sequentially, taking a profile, when these each factor is decided.

  Further, in the above-described example, the proximity of the raindrop 9 is determined by comparing using the value obtained by dividing the first capacitance value C1 by the second capacitance value C2. In addition, for example, the first capacitance value C1 is compared using a value obtained by dividing the first capacitance value C1 by the sum of the first capacitance value C1 and the second capacitance value C2, or other calculations are performed. You may make it determine proximity | contact using a method.

  Thus, according to the raindrop detection device of this example, for example, when the threshold Th2 is large, the directionality of the sensor sensitivity of each of the capacitance sensor units 10 and 20 is high, and when the threshold Th2 is small, it is low. Can do. Therefore, the detection ranges Z1 and Z2 can be arbitrarily set on the surfaces of the capacitance sensor units 10 and 20 disposed on the instrument panel 2 and the rear tray 3 or the rear gate 4 by arbitrarily adjusting the directivity. This makes it possible to reliably and accurately detect raindrops 9 in the detection ranges Z1 and Z2 having desired directivity.

  The CV conversion circuit 21 of the circuit unit 30 described above uses, for example, a known timer IC in which the duty ratio of the output pulse is changed by a resistor and a capacitor, but is not limited thereto.

  That is, for example, a method in which a sine wave is applied to directly measure an impedance from a voltage change or a current value due to a capacitance value, a method in which an oscillation circuit is configured including a capacitance value to be measured, and an oscillation frequency is measured, RC A charge / discharge circuit is configured to measure the charge / discharge time, a charge charged with a known voltage is transferred to a known capacity and the voltage is measured, or an unknown capacity is charged with a known voltage and the charge is charged. There is a method to measure the number of times until the known capacity is charged to a predetermined voltage by moving it to a known capacity multiple times, setting a threshold value for the detected capacitance value, or a waveform of the capacitance May be processed as a trigger when the corresponding capacitance waveform is obtained.

  Further, although it is assumed that the CV conversion circuit 21 of the circuit unit 30 converts the capacitance into voltage, it is only necessary to convert the data into data that can be handled electrically or as software. For example, the capacitance is converted into a pulse width. It may be converted or directly converted into a digital value.

  Further, in the raindrop detection device described above, the sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13 of each capacitance sensor unit 10, 20 are connected to the upper surface of the instrument panel 2 of the vehicle 1, 1 </ b> A and the upper surface of the rear tray 3. Or the edge of the window frame of the rear gate 4. An example in which detection of the raindrop 9 is determined by comparing the first capacitance value C1 of only the sensor electrode 11 with the second capacitance value C2 of the sensor electrode 11 and the auxiliary electrode 13 will be described. However, these may be as follows, for example.

  FIG. 8 is an explanatory diagram illustrating another example of the overall configuration of the capacitance sensor unit and the circuit unit of the raindrop detection device. The raindrop detection device of this example has a configuration in which a dummy sensor electrode (dummy electrode) 19 is arranged in addition to the sensor electrode 11, and the CV conversion circuit 21 of the circuit unit 30 is configured to perform a differential operation. ing.

  Specifically, as shown in FIG. 8, for example, the sensor electrode 11 is connected to the positive input end of the differential amplifier circuit, and the dummy electrode 19 is connected to the negative input end of the differential amplifier circuit. The value of the capacitance Cb is subtracted. Then, the raindrop 9 is detected by comparing the output value with a threshold value by a comparator or the like.

  As an operation of such a CV conversion circuit 21, for example, when the switch S1 is open (OFF), the switch S2 is grounded (GND), and the switch S3 is closed (ON), the switch S3 is operated. Open (OFF), switch S2 is switched to Vr, and switch S1 is connected to the inverting input of the operational amplifier. Then, the capacitances Ca and Cf are charged with CaVr, and the capacitances Cb and Cf are charged with CbVr.

  Next, after the switch S1 is opened (OFF) and the switch S2 is grounded (GND), the output voltage V when the switch S1 is grounded (GND) is measured. The voltage at this time is V / Vr = {(Cf + Ca) / Cf} − {(Cf + Cb) / Cf}, and a voltage corresponding to the ratio between the capacitance Ca and the capacitance Cb is output.

  As described above, the CV conversion circuit 21 is configured to perform a differential operation (differential circuit), so that the temperature characteristics of the circuit can be offset and common mode noise can be reduced. At this time, for example, the dummy electrode 19 is connected to the negative side input terminal of the differential amplifier circuit. If the dummy electrode 19 is capacitively coupled to the raindrop 9, the sensitivity of the sensor itself is lowered.

  For this reason, the area of the dummy electrode 19 is made sufficiently small with respect to the sensor electrode 11, or another shield electrode 47 having the same potential is provided between the dummy electrode 19 and the raindrop 9, so It is necessary to reduce the capacitive coupling.

  In the shield drive circuit 24 described above, when the duty ratio changes according to the capacitance C, the output waveform of the sensor electrode 11 changes depending on the measured capacitance. To do. For this reason, a 1 × amplifier circuit may be configured with a voltage follower such as an operational amplifier or a source follower such as an FET, and the output of the sensor electrode 11 may be input and the output connected to the shield electrode 12 or the like. .

  Further, when the CV conversion circuit 21 operates differentially, the shield drive circuit 24 has a rectangular waveform with the voltage Vr and GND as the output waveform of the sensor electrode 11 and the frequency becomes the switching frequency of the switch. Therefore, since it does not vary depending on the capacitance value, the non-inverting input of the operational amplifier shown in FIG. 8 may be connected to the shield electrode 12 or the like. However, when a driving current is required, a rectangular wave of Vr and GND may be separately generated through an operational amplifier with a high output current.

  Furthermore, in the above-described embodiment, the sensor electrode 11 is connected to the CV conversion circuit 21, the shield electrode 12 is connected to the shield drive circuit 24, and the auxiliary electrode 13 is connected to the shield electrode 24 or C via the changeover switch SW. It was configured to be connected to the −V conversion circuit 21. In addition, for example, when the CV conversion circuit 21 operates differentially, the sensor electrode 11 is connected to the negative side input end shown in FIG. 8, the shield electrode 12 is connected to the shield drive circuit 24, and You may comprise so that the auxiliary electrode 13 may each be connected to a plus side input end.

  In this case, in the operation 2 described above, the auxiliary electrode 13 is connected to the sensor electrode 11 and there is almost no directivity. However, in the case of the operation 1 described above, the value of the capacitive coupling between the auxiliary electrode 13 and the raindrop 9 is subtracted from the capacitance value of the sensor electrode 11, resulting in a loose directivity. Similar to the case described above, the same effect can be obtained by comparing the detection values in the operation 1 and the operation 2.

  Furthermore, in the above-described embodiment, the auxiliary switch 13 is configured to be connected to the shield drive circuit 24 during the operation 1 and connectable to the CV conversion circuit 21 during the operation 2 by the changeover switch SW. In the case of 1 and operation 2, the equal capacitance line (surface) M is made variable. In addition, the auxiliary electrode 13 is configured to be connected to the shield drive circuit 24 at the time of operation 1, for example, to be open, grounded, or connectable to a predetermined potential at the time of operation 2, or for example at the time of operation 1 Can be connected to an open, grounded or predetermined potential, and can be connected to the CV conversion circuit 21 in the operation 2 to obtain the same effect. In this way, the auxiliary electrode 13 is connected to the open state by the changeover switch SW, or connected to the ground or other potential (including a potential equivalent to the ground, pulse, charging voltage, sine wave, etc.). May be.

  Note that the change-over switch SW only needs to have a structure capable of switching electrical connection. For example, an electronic circuit switch such as an FET or a photo MOS relay or a mechanical switch such as a contact switch can be employed. In addition to the above, the shape of the sensor electrode 11 may be various shapes such as a circle, an ellipse, a rectangle, and a polygon. For example, the back side of the sensor electrode 11 is also set to the detection ranges Z1 and Z2. In that case, the shield electrode 12 may not be installed.

  The auxiliary electrode 13 is arranged so as to surround the entire periphery of the sensor electrode 11, but if the detection range Z1, Z2 can be set, the auxiliary electrode 13 is in a state of surrounding a part or adjacent to the part. It may be arranged. Further, for example, when the sensor electrode 11 is surrounded, the sensor electrode 11 may be arranged concentrically (the center is the same).

  Next, a capacitance sensor unit and a circuit unit of a raindrop detection device according to another embodiment of the present invention will be described with reference to FIGS. In the raindrop detection apparatus according to the embodiment described above, the output from the CV conversion circuit 21 of the circuit unit 30 is the second capacitance value indicating the capacitance detected by the sensor electrode 11 and the auxiliary electrode 13. Either C2 or the first capacitance value C1 indicating the capacitance detected only by the sensor electrode 11.

  For this reason, the capacitance value detected by the structure around the installation place of the sensor electrode 11 (including each capacitance sensor unit 10, 20) may differ. In such a case, the comparison result obtained by comparing the first and second capacitance values C1 and C2 may change depending on the structure around the place where the sensor electrode 11 is installed. In order to avoid such a situation, the internal configuration of the circuit unit 30 may be further set as follows, for example.

  FIG. 9 is an explanatory diagram illustrating an example of the overall configuration of the capacitance sensor units 10 and 20 and the circuit unit 30 of the raindrop detection device according to another embodiment of the present invention, and FIG. 10 is a wiper including the raindrop detection device. The flowchart which shows the example of the wiper operation control processing procedure of each wiper 51 and 52 by an operation control apparatus, FIG. 11 shows the other example of the whole electrostatic capacitance sensor part 10 and 20 of the raindrop detection apparatus, and the circuit part 30. It is explanatory drawing. 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. 9, when the raindrop 9 is not close to the determination circuit 25 including, for example, a CPU in addition to the CV conversion circuit 21 and the shield drive circuit 24 described above, The initial capacitance storage device 26 that stores the capacitance value (initial capacitance) of the switch, the switch control circuit 27 that controls the switching operation of the changeover switch SW, and the buffer 28 are configured.

  As an outline of the detection operation of the detection target (raindrop 9) of the raindrop detection apparatus having the circuit unit 30 configured as described above, for example, the electrostatic capacity sensor units 10 and 20 are similarly mounted on the vehicles 1 and 1A. It is arranged on the upper surface of the panel 2 and the upper surface of the rear tray 3 or the window frame edge of the rear gate 4. Thereafter, the capacitance value (initial capacitance) in the operation 1 and the operation 2 when the raindrop 9 is not approaching each of the capacitance sensor units 10 and 20 is switched by the switch control circuit 27 under the control of the switch SW. Detect each.

  Then, these values are stored in the initial capacity storage device 26, and the initial capacity is determined from the first and second electrostatic capacitance values C1 and C2 in the actual operations 1 and 2 described above in the determination circuit 25. These initial capacities stored in the storage device 26 are subtracted and compared. Based on the comparison result thus obtained, it is determined whether or not the raindrop 9 exists in the detection ranges Z1 and Z2 on the sensor electrode 11.

  More specifically, the initial capacity is stored as the first initial capacity when the changeover switch SW is connected to the shield drive circuit 24 side by the control of the switch control circuit 27 as the first initial capacity. It is stored in the device 26. In addition, the operation at the time of the operation 2 when the changeover switch SW is connected to the CV conversion circuit 21 side is stored in the initial capacity storage device 26 as the second initial capacity.

  Then, in the actual operation 1, the determination circuit 25 subtracts the first initial capacity stored in the initial capacity storage device 26 from the detected first capacitance value C1 and performs 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 C2. ).

  That is, as shown in FIG. 10, first, the wiper operation control device starts the processing of the raindrop detection device, for example, triggered by the ignition switch of the vehicle 1, 1 </ b> A being turned on as an accessory, The first detection value and the second detection value as described above are calculated (step S202), and these are compared to calculate a comparison value (step S203).

  Thereafter, based on the first or second detection value, it is determined whether or not the raindrop 9 is approaching (step S204). At the same time, whether the comparison value of the first detection value and the second detection value is, for example, a predetermined threshold value or more (or less than a predetermined threshold value or less than a predetermined threshold value). It is determined whether or not (step S205).

  That is, here, it is determined whether or not there is a raindrop 9 in the detection ranges Z1 and Z2 based on the detection values 1 and 2 and the comparison result. In addition, the detection value 2 at the time of the said operation | movement 2 with which the sensor electrode 11 and the auxiliary electrode 13 are connected to the CV conversion circuit 21 is a detection value in the state where there is no directivity in sensor sensitivity, and the raindrop 9 The output depends on the approach to the capacitance sensor units 10 and 20.

  When it is determined that the raindrop 9 is close (Y in step S204) and the comparison value is determined to be equal to or greater than a predetermined threshold (Y in step S205), the raindrop 9 is determined to be detected. (Step S206), the wiper operation control of each wiper 51, 52 is performed as described above (Step S207).

  Although it is determined that the raindrop 9 is close (Y in step S204), if it is determined that the comparison value is not equal to or greater than the predetermined threshold value (N in step S205), it is determined that the raindrop 9 is not detected. (Step S208). Then, for example, a non-detection signal A (for example, a high impedance, a predetermined potential, or the like) that is a disable signal indicating that no raindrop 9 exists in the detection ranges Z1 and Z2 when directivity is given is determined and output. Output as.

  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 raindrop 9 is close (step S204). If it is determined that they are not close to each other (N in step S204), the process proceeds to step S208 and it is determined that these are not detected. Then, for example, a non-detection signal B (a signal different from the non-detection signal A) that is a disable signal indicating that the raindrop 9 is not within the detection ranges Z1 and Z2 on the sensor electrode 11 is output as a determination output.

  Thereafter, for example, it is determined whether or not the process of the raindrop detection apparatus is ended by using the ignition switch of the vehicles 1 and 1A as a trigger (step S209). If it is determined that the process is to be terminated (Y in step S209), the series of wiper operation control processes according to this flowchart is terminated. When it is determined that the process is not ended (N in step S209), the process proceeds to step S202, the first and second detection values are calculated, and the subsequent processes are repeated.

  In this way, by making the output of the determination circuit 25 into an enable signal or a disable signal, for example, according to the determination result, when the raindrop 9 is in the detection range Z1, Z2 on the sensor electrode 11, the enable signal is sent to the buffer 28. The detection value 1 is output from the buffer 28. When the raindrop 9 is not within the detection ranges Z1 and Z2 on the sensor electrode 11, the determination output as a disable signal is fixed to a predetermined voltage such as a ground voltage or a reference voltage, or becomes a high impedance output.

  When the raindrop 9 is within the detection ranges Z1 and Z2 on the sensor electrode 11, in addition to the detection value 1, the detection value 2 and the first or second capacitance values C1 and C2 are output. Also good. These detection value 1, detection value 2, and first and second capacitance values C1 and C2 indicate values corresponding to the distance of the raindrop 9 to the sensor electrode 11, for example.

  Thus, according to the circuit unit 30 configured as described above, when the raindrop 9 is within the detection range Z1, Z2, a detection value corresponding to the distance is output, and when the raindrop 9 is not within the detection range Z1, Z2, a predetermined value is output. Outputs voltage. Therefore, it is possible to determine whether or not there is a raindrop 9 in the detection ranges Z1 and Z2, and if so, how long it is. That is, it is possible to increase the intensity of the directivity of the sensor sensitivity of each of the capacitance sensor units 10 and 20 or to set the directivity in more detail.

  Further, as another example of a method for avoiding the dependence on the structure around the place where the electrostatic capacitance sensor units 10 and 20 are installed, these are maintained by adjusting the reference voltage as follows. It is also possible. That is, as shown in FIG. 11, the circuit unit 30 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 when measuring the initial capacitances of the first and second initial capacitances as described above. Here, the reference voltage adjustment circuit 40 includes a comparator 41, a control circuit 42, a register 43, a D / A converter 44, and an adjustment unit 45.

  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. Then, the set value of the register 43 is changed under the control of the control circuit 42 based on the comparison result.

  Further, after the output of the register 43 is converted from a digital signal to an analog signal by the D / A converter 44, the voltage is adjusted by the adjusting unit 45, and the output from the adjusting unit 45 is used to adjust the voltage of the CV conversion circuit 21. Adjust the input. In this way, in the operation 1 when the raindrop 9 is not in proximity to each of the capacitance sensor units 10 and 20, the setting of the register 43 is performed when the output from the CV conversion circuit 21 is closest to the reference potential. The value is fixed and the output of the first initial capacity is used as the reference voltage, and the set value (set value 1) at that time is stored.

  At the same time, in the operation 2 when the raindrop 9 is not close to each of the capacitance sensor units 10 and 20, the set value of the register 43 is set when the output from the CV conversion circuit 21 is closest to the reference potential. The second initial capacitance output is fixed as the reference potential, 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 set value 1 of the register 43 is fixed 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 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.

  Then, by comparing these detection value 1 and detection value 2, whether or not there are raindrops 9 in the detection ranges Z1 and Z2 on the sensor electrode 11 and how far the distance is, if any. Determine. 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. 12 is an explanatory diagram illustrating an example of the overall configuration of the capacitance sensor unit and the circuit unit of the raindrop detection device according to still another embodiment of the present invention, and FIG. 13 is an operation concept during the detection operation of the raindrop detection device. FIG. 14 to FIG. 16 are explanatory diagrams for explaining the relationship between the detection object and the lines of electric force during the first detection operation (operation 3) of the raindrop detection apparatus.

  Moreover, FIGS. 17-19 is explanatory drawing for demonstrating the relationship between the detection target object and electric force line at the time of the 2nd detection operation (operation | movement 4) of the raindrop detection apparatus. It should be noted that a description overlapping the part already described in the above-described embodiment may be omitted.

  As shown in FIG. 12, the wiper operation control device provided with the raindrop detection device according to the present embodiment has the same configuration as the wiper operation control device provided with the raindrop detection device according to the above-described embodiment, and the front static The capacitance sensor unit 10, the rear capacitance sensor unit 20, the circuit unit 30, and the wiper operation control unit 50 are configured.

  The front electrostatic capacitance sensor unit 10 and the rear electrostatic capacitance sensor unit 20 are auxiliary electrodes formed in a square shape so as to surround the sensor electrode 11 in the same manner as the sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13. The electrode 13A is provided.

  The sensor electrode 11 is provided mainly for detecting the raindrop 9 existing in the detection ranges Z1, Z2 of the detection area on the detection surface side. The shield electrode 12 has the above-described action. The auxiliary electrode 13 </ b> A is provided mainly to vary the equal capacitance line (surface) on the equal electrostatic side on the detection surface side of the sensor electrode 11.

  The circuit unit 30 is directly connected to the CV conversion circuit 21 connected to the sensor electrode 11 or the auxiliary electrode 13A, the A / D converter 22, the CPU 23, and the shield electrode 12, and the sensor electrode 11 or the auxiliary electrode. And a shield drive circuit 24 connected to 13A.

  The circuit unit 30 also includes a first changeover switch SW1 that switches the input from the sensor electrode 11 to the CV conversion circuit 21 or the shield drive circuit 24, and the input from the auxiliary electrode 13A to the shield drive circuit 24 or the CV conversion. A second changeover switch SW2 for switching to the circuit 21 is provided. The first and second changeover switches SW1 and SW2 are configured to be switchable to the A side and the B side (see FIG. 12 and the like), respectively.

  The CV conversion circuit 21 converts the capacitance detected by the sensor electrode 11 or the auxiliary electrode 13A into a voltage. The A / D converter 22 operates in the same manner as described above. The CPU 23 controls the entire raindrop detection device, and controls the operation of alternate connection (an alternative connection to the A side or B side) of the first and second changeover switches SW1, SW2, for example. The detection of the detection object (raindrop 9) in the detection area (proximity or presence of the raindrop 9) is determined. The shield drive circuit 24 drives the shield electrode 12 and the auxiliary electrode 13A or the sensor electrode 11 to, for example, the same potential as the sensor electrode 11.

  The structures and configurations of the capacitance sensor units 10 and 20, the circuit unit 30 and the wiper operation control unit 50, and the structures and configurations of the electrodes 11 to 13A are the same as those already described in the above-described embodiments. Therefore, the description is omitted here. Note that the first changeover switch SW1 is configured such that, for example, when the sensor electrode 11 is not connected to the CV conversion circuit 21, the sensor electrode 11 can be opened, grounded, or connected to a predetermined potential. The second changeover switch SW2 May be configured such that when the sensor electrode 11 is connected to the CV conversion circuit 21, the auxiliary electrode 13A can be opened, grounded, or connected to a predetermined potential.

  The shield drive circuit 24 is configured to give the auxiliary electrode 13A a potential equivalent to that of the sensor electrode 11, or to give the sensor electrode 11 a potential equivalent to that of the auxiliary electrode 13A. The first changeover switch SW1 is configured so that the sensor electrode 11 can be connected to the shield drive circuit 24 when the sensor electrode 11 is not connected to the CV conversion circuit 21, and the second changeover switch SW2 is configured so that the sensor electrode 11 is connected to the shield drive circuit 24. The auxiliary electrode 13 </ b> A may be configured to be connectable to the shield drive circuit 24 when connected to the CV conversion circuit 21.

  Further, the shield drive circuit 24 may be configured to apply a potential equivalent to that of the sensor electrode 11 to the auxiliary electrode 13A. In this case, the first changeover switch SW1 has the sensor electrode 11 connected to the CV conversion circuit 21. The auxiliary electrode 13A may be open, grounded, or connectable to a predetermined potential when not connected. The second changeover switch SW2 may be configured to connect the auxiliary electrode 13A to the shield drive circuit 24 when the sensor electrode 11 is connected to the CV conversion circuit 21.

  The shield drive circuit 24 is configured to give the sensor electrode 11 the same potential as the auxiliary electrode 13A. In this case, the first changeover switch SW1 is not connected to the CV conversion circuit 21. Sometimes, the auxiliary electrode 13A may be configured to be connectable to the shield drive circuit 24. The second changeover switch SW2 may be configured so that the auxiliary electrode 13A can be opened, grounded, or connected to a predetermined potential when the sensor electrode 11 is connected to the CV conversion circuit 21.

  Next, the detection operation of the detection target (raindrop 9) of the raindrop detection apparatus configured as described above will be described. First, under the control of the CPU 23, both the first and second changeover switches SW 1 and SW 2 are switched to the A side, and the sensor electrode 11 is connected to the CV conversion circuit 21. In addition, an operation (operation 3) when the shield electrode 12 and the auxiliary electrode 13A are connected to the shield drive circuit 24 will be described.

  In the case of the operation 3, the connection state of the sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13A with the circuit unit 30 is as shown in FIG. That is, as described above, only the sensor electrode 11 is connected to the CV conversion circuit 21, and the shield electrode 12 and the auxiliary electrode 13 </ b> A are connected to the shield drive circuit 24. Thereby, the electrostatic capacitance C with the detection objects X, Y, W is detected by the CV conversion circuit 21 only by the sensor electrode 11.

  In addition, the back side of the sensor electrode 11 of each of the capacitance sensor units 10 and 20 is covered with the shield electrode 12. For this reason, the sensor sensitivity on the back surface side of the sensor electrode 11 is considerably lower than that on the detection surface side because only the electric lines of force that wrap around from the detection surface (front surface) of the sensor electrode 11 are detected. Here, the detection target X as the raindrop 9 is described as a detection target existing in the detection ranges Z1 and Z2, and the detection targets Y and W as the raindrop 9 are described as detection targets existing outside the detection ranges Z1 and Z2. To do.

  As shown in FIG. 14, the electric lines of force P1 from the sensor electrode 11 to the detection target X are less affected by the electric lines of force P2 (shield) from the auxiliary electrode 13A.

  On the other hand, as shown in FIG. 15, the electric lines of force P1 from the sensor electrode 11 with respect to the detection target Y at a distance substantially equal to the detection target X are affected by the electric lines of force P2 (shield) from the auxiliary electrode 13A. In response to this, it decreases compared to the case of the detection object X. For this reason, the detection target Y is weaker in capacitive coupling with the sensor electrode 11 than the detection target X.

  Thereby, the identification of the detection objects X and Y during the operation 3 (that is, the distinction between the detection ranges Z1 and Z2 or the detection ranges Z1 and Z2) can be easily performed. However, as shown in FIG. 16, in the detection target W closer to the sensor electrode 11 than the detection target Y, the electric lines of force P1 from the sensor electrode 11 are the same as those for the detection target X in FIG. , The output from the CV conversion circuit 21 is the same.

  That is, the detection target object X and the detection target object W are on the equipotential surface (line) M in FIG. 13, and the detection value (capacitance value) in the operation 3 is the same. For this reason, it is difficult to identify whether the detection object W exists in the detection ranges Z1 and Z2 or outside the detection ranges Z1 and Z2 only by the operation 3. In this embodiment as well, as in the above-described embodiment, the determination is not made only by the operation 3, but the electrostatic capacitance as the first capacitance value detected by the CV conversion circuit 21 at the time of the operation 3 is determined. The capacitance value C1 is stored in the storage means by the CPU 23.

  Next, under the control of the CPU 23, both the first and second changeover switches SW 1 and SW 2 are switched to the B side, and the auxiliary electrode 13 A is connected to the CV conversion circuit 21. In addition, an operation (operation 4) when the shield electrode 12 and the sensor electrode 11 are connected to the shield drive circuit 24 will be described.

  In addition, the structure corresponding to FIG. 13 which shows the connection state with the circuit part 30 of the sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13A in the raindrop detection apparatus in the case of the operation | movement 4 has each changeover switch SW1, SW2 in FIG. Switched to the B side. For this reason, illustration and description are omitted here.

  In this operation 4, only the auxiliary electrode 13 </ b> A is connected to the CV conversion circuit 21, and the shield electrode 12 and the sensor electrode 11 are connected to the shield drive circuit 24. Thereby, the capacitance C with the detection objects X, Y, W is detected by the CV conversion circuit 21 only by the auxiliary electrode 13A. It is assumed that various conditions such as the arrangement positions of the detection objects X, Y, and W with respect to the capacitance sensor units 10 and 20 are the same as those in the operation 3.

  In the case of this operation 4, as shown in FIG. 17, the electric force line P2 (shield) from the sensor electrode 11 with respect to the detection target X has a great influence on the electric force line P1 from the auxiliary electrode 13A. For this reason, the detection object X has weak capacitance coupling with the auxiliary electrode 13A, and the capacitance value detected by the CV conversion circuit 21 is compared with the detection object X in the operation 3. Become smaller.

  On the other hand, as shown in FIG. 18, the electric force line P2 (shield) from the sensor electrode 11 with respect to the detection target Y is reduced as compared with the case with respect to the detection target X, and the electric force line P1 from the auxiliary electrode 13A. Increases compared to the case of the detection object X. For this reason, in the case of the operation 4, the detection target Y has a strong capacitive coupling with the auxiliary electrode 13A, and the capacitance value detected by the CV conversion circuit 21 is the detection target in the operation 3. Compared to the case for the object Y, it becomes larger.

  Further, as shown in FIG. 19, the electric lines of force P1 from the auxiliary electrode 13A to the detection object W are larger than the electric lines of force P1 from the auxiliary electrode 13A to the detection object X in FIG. The influence of the electric lines of force P2 (shield) from the electrode 11 is also small. For this reason, in the operation 4, the output from the CV conversion circuit 21 in the detection target W is larger than that in the detection target X. Then, the capacitance value C2 as the second capacitance value detected by the CV conversion circuit 21 during the operation 4 is stored in the storage means by the CPU 23.

  If the first and second capacitance values C1 and C2 are detected in this way, the CPU 23 compares these capacitance values C1 and C2 stored in the storage means. For example, in the detection object X described above, the first capacitance value C1 in the operation 3 is larger than the second capacitance value C2 in the operation 4, but in the detection object Y, the operation The first capacitance value C1 at 3 is smaller than the second capacitance value C2 at operation 4. For this reason, in the detection target W, the first capacitance value C1 in the operation 3 and the second capacitance value C2 in the operation 4 are approximately the same.

  As described above, the CPU 23 determines how far the detection target exists from the center of the sensor electrode 11 by comparing the value of the capacitance value C2 with the capacitance value C1. Is possible. At this time, if the comparison value of the capacitance values C1 and C2 is, for example, a predetermined threshold value or more (or less than a predetermined threshold value or less than a predetermined threshold value), the sensor electrode 11 If it is set so that it can be determined that it is within the upper detection ranges Z1 and Z2, directivity can be arbitrarily given.

  In the explanatory diagrams shown in FIGS. 13 to 19, the detection value in the operation 3 is larger than the detection value in the operation 4 for the detection target X, and the detection value in the operation 3 is the detection value in the operation 3 for the detection target Y. Smaller than the detected value. In the detection target W, the detection value in the operation 3 and the detection value in the operation 4 are described as examples. However, when various conditions such as the arrangement shape and the arrangement area of the sensor electrode 11 and the auxiliary electrode 13A change, the vertical relationship between the operation 3 and the operation 4 on the detection objects X, Y, and W changes.

  However, the ratio (C2 / C1) of the second capacitance value C2 in the operation 4 to the first capacitance value C1 in the operation 3 is always the detection object X <the detection object Y (or the detection object W). ) So that it can be distinguished. Therefore, if the comparison formula between the operation 3 and the operation 4 is changed for each condition, the detection objects X, Y, and W can be determined. Note that the comparison formulas, comparison values, various coefficients, predetermined threshold values (Th1, Th2), and the like are the same as those described in the above-described embodiment, and thus description thereof is omitted here.

  In addition, although there are cases where it cannot be expressed by a mathematical expression depending on conditions, the values of the capacitance values C1 and C2 at the position of the detection target (raindrop 9) attached to the windshield and rear glass are measured and profiled in advance. What is necessary is just to compare each profile with an actual detection value.

  Thus, according to this raindrop detection apparatus, for example, when the predetermined threshold Th2 is large, the directionality of the sensor sensitivity of each of the capacitance sensor units 10 and 20 is high, and when it is small, the directivity is high. The strength can be low. Thereby, the directivity of the sensor sensitivity can be arbitrarily set, and the detection ranges Z1 and Z2 on the sensor electrode 11 can be arbitrarily determined, and the detection target (raindrop 9) can be reliably detected with a simple configuration. become able to.

  Based on the determination result, for example, when the raindrop 9 is detected, the wiper operation control unit 50 outputs a control signal for operating the wipers 51 and 52 to the drive motor to operate the wipers 51 and 52. . In this way, each wiper 51, 52 can be automatically operated or stopped in the vehicle 1, 1A.

  Note that various configurations and operations of the CV conversion circuit 21 of the circuit unit 30 are the same as those described in the above-described embodiment, and thus description thereof is omitted here. In the raindrop detection device according to the present embodiment, the sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13A are arranged, and the electrostatic capacitance value C1 of the sensor electrode 11 and the electrostatic capacitance value C2 of the auxiliary electrode 13A are obtained. The comparison and determination of the detection target object have been described as examples. In addition, as described with reference to FIG. 8 in the above-described embodiment, the dummy electrode 19 may be disposed and the CV conversion circuit 21 may be configured to perform a differential operation. Since the various configurations and operations are the same as those described above, the description thereof is omitted here.

  Further, since the various configurations and operations of the modified example of the shield drive circuit 24 and the modified examples of the first and second changeover switches SW1 and SW2 are the same as those described in the above-described embodiment, Description is omitted.

  In the raindrop detection device according to the present embodiment, the auxiliary electrode 13A is arranged so as to surround the entire periphery of the sensor electrode 11. Therefore, each of the capacitance sensor units 10 and 20 has the same directivity in all directions of the detection surface of the sensor electrode 11 (that is, the detection ranges Z1 and Z2 are the same in any direction with respect to the sensor electrode 11). If there is a direction in which it is not desired to have the property, for example, the following may be performed.

  That is, the auxiliary electrode 13A is not disposed in a direction in which directivity is not desired, and the auxiliary electrode 13A is formed in a U shape, a C shape, an L shape, a semicircle, or the like, for example. It is also possible to reduce the directivity in the direction where there is no noise.

  Further, since the output from the CV conversion circuit 21 of the circuit unit 30 described above is either the first capacitance value C1 or the second capacitance value C2, each sensor electrode 11 (including each of the sensor electrodes 11) is included. There are cases where the capacitance value detected differs depending on the structure around the installation location of the capacitance sensor units 10 and 20).

  Then, the comparison result obtained by comparing the first and second capacitance values C1 and C2 may change depending on the structure around the place where the sensor electrode 11 is installed. In order to avoid such a situation, the configuration of the circuit unit 30 may be further set as follows, for example.

  FIG. 20 is an explanatory diagram showing an example of the overall configuration of the capacitance sensor unit and the circuit unit of the raindrop detection device according to still another embodiment of the present invention, and FIG. 21 shows the capacitance sensor unit of the raindrop detection device and It is explanatory drawing which shows the other example of the whole structure of a circuit part. Note that, in the above-described embodiment, the same reference numerals are given to portions overlapping with the already described portions, and the description is omitted.

  As shown in FIG. 20, the circuit unit 30 includes a CV conversion circuit 21, a shield drive circuit 24, a determination circuit 25, an initial capacity storage device 26 that stores the above-described initial capacity, and a switching operation of each switch SW1 and SW2. A switch control circuit 27 for controlling the signal and a buffer 28.

  As an outline of the detection operation (raindrop 9) of the detection object (raindrop 9) of the raindrop detection apparatus having such a circuit unit 30, for example, after each electrostatic capacitance sensor unit 10, 20 is installed at a predetermined installation location, The capacitance value (initial capacitance) when not approaching each capacitance sensor unit 10, 20 is detected by switching the change-over switches SW 1, SW 2 under the control of the switch control circuit 27, and the initial capacitance storage device 26. And store these values.

  Then, the initial capacitance stored in the initial capacity storage device 26 is subtracted from the first and second capacitance values C1 and C2 in the actual operation 3 and 4 described above in the determination circuit 25 and compared. Based on the comparison result, it is determined whether or not the raindrop 9 exists in the detection ranges Z1 and Z2 on the sensor electrode 11.

  Specifically, the initial capacity is set as the first initial capacity at the time of the above operation 3 when the respective switches SW1 and SW2 are connected to the A side under the control of the switch control circuit 27. The switch at the time of the above operation 4 when the switches SW1 and SW2 are connected to the B side is stored in the initial capacity storage device 26 as the second initial capacity.

  In the actual operation 3, the determination circuit 25 subtracts the first initial capacitance stored in the initial capacitance storage device 26 from the detected first capacitance value C1 and performs the first detection. A value (detection value 1), and in the case of operation 4, the second detection value is obtained by subtracting the second initial capacitance stored in the initial capacitance storage device 26 from the detected second capacitance value C2. (Detection value 2).

  Thereafter, the determination circuit 25 compares the detection value 1 and the detection value 2, and determines whether or not there is a raindrop 9 in the detection ranges Z1 and Z2 based on the comparison result. For example, the detection value 1 at the time of the operation 3 is an output depending on the approach of the raindrop 9 to the electrostatic capacitance sensor units 10 and 20. Since subsequent operations, functions, effects, and the like are the same as those described in the above-described embodiment, description thereof is omitted here.

  The first and second initial capacitances described above may be, for example, digitally converted from the voltage at the time of initial capacitance measurement by an A / D converter or the like and held in a register or a memory. Thus, it is possible to hold these by adjusting the reference voltage. That is, as shown in FIG. 21, the circuit unit 30 includes a CV conversion circuit 21, a shield drive circuit 24, a reference voltage adjustment circuit 40, and a subtraction circuit 31.

  The reference voltage adjustment circuit 40 is for adjusting the output of the CV conversion circuit 21 to the reference potential at the time of initial capacitance measurement of the first and second initial capacitances as described above. , A comparator 41, a control circuit 42, a register 43, a D / A converter 44, and an adjustment unit 45. Since these configurations, operations, and the like are also the same as those described in the above-described embodiment, description thereof is omitted here.

  The output of the first and second initial capacitors is set as a reference voltage by the reference voltage adjustment circuit 40, and the output of the CV conversion circuit 21 thus set to the reference voltage is applied to, for example, the positive side input terminal of the subtraction circuit 31. Input, input the reference voltage RV to the negative side input terminal, subtract the output by the reference voltage RV, subtract the first and second initial capacity, and similarly whether there is a raindrop 9 in the detection range Z1, Z2 It can be determined whether or not the distance is, if any.

  As described above, according to the raindrop detection device according to the above-described embodiment, the raindrops attached to the windshield and the rear glass in the detection ranges Z1 and Z2 on the sensor electrode 11 by the capacitance sensor units 10 and 20. Whether or not there is 9 can be determined. Based on the determination result, when the raindrop detection device detects the raindrop 9, the wiper operation control device controls the drive motor by the wiper operation control unit 50 to operate the wipers 51 and 52. In this way, when it is detected that the raindrop 9 has actually adhered to the windshield or rear glass, the wipers 51 and 52 can be automatically operated in the vehicles 1 and 1A.

  In addition, although the raindrop detection apparatus concerning embodiment mentioned above demonstrated as what detects the raindrop 9 adhering to the windshield and rear glass of the vehicles 1 and 1A, it is made to detect the raindrop 9 adhering to the other window glass. May be. For example, when a wiper is provided in a train or the like, the raindrop 9 attached to the window glass of the train can be configured to be detectable.

DESCRIPTION OF SYMBOLS 1 Vehicle 1A Vehicle 2 Instrument panel 3 Rear tray 4 Rear gate 9 Raindrop 10 Front electrostatic capacitance sensor part 11 Sensor electrode 12 Shield electrode 13 Auxiliary electrode 13A Auxiliary electrode 19 Dummy electrode 20 Rear electrostatic capacitance sensor part 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 28 Buffer 30 Circuit Unit 31 Subtraction Circuit 40 Reference Voltage Adjustment Circuit 41 Comparator 42 Control Circuit 43 Register 44 D / A Converter 45 Adjustment Unit 50 Wiper Operation Control Unit

Claims (11)

A sensor electrode disposed on at least one of an upper surface of a vehicle instrument panel, an upper surface of a rear tray, and a window frame edge of a rear gate so that a detection surface exists toward the window glass;
An auxiliary electrode provided in the vicinity of the sensor electrode;
A detection circuit connected to at least the sensor electrode and detecting a capacitance value based on a capacitance from the connected electrode;
A changeover switch capable of selectively switching between a first connection state in which the auxiliary electrode is not connected to the detection circuit and a second connection state in which the auxiliary electrode is connected to the detection circuit;
A comparison value comparing a first capacitance value from the detection circuit in the first connection state with a second capacitance value from the detection circuit in the second connection state; and the first Raindrop detection means comprising: raindrop determination means for determining whether raindrops attached to the window glass are within a detection range on the sensor electrode based on the first or second capacitance value apparatus. The raindrop detection device according to claim 1, wherein the change-over switch is configured to be able to open, ground, or connect the auxiliary electrode to a predetermined potential in the first connection state. A shield driving circuit for applying a potential equal to that of the sensor electrode to the auxiliary electrode;
The raindrop detection device according to claim 1, wherein the change-over switch is configured to be able to connect the auxiliary electrode to the shield drive circuit in the first connection state. A sensor electrode disposed on at least one of an upper surface of a vehicle instrument panel, an upper surface of a rear tray, and a window frame edge of a rear gate so that a detection surface exists toward the window glass;
An auxiliary electrode provided in the vicinity of the sensor electrode;
A detection circuit for detecting a capacitance value based on a capacitance from the sensor electrode;
A shield drive circuit for applying a potential equal to that of the sensor electrode to the auxiliary electrode;
A changeover switch capable of selectively switching between a first connection state in which the auxiliary electrode is connected to the shield drive circuit and a second connection state in which the auxiliary electrode is opened, grounded or connected to a predetermined potential;
A comparison value comparing a first capacitance value from the detection circuit in the first connection state with a second capacitance value from the detection circuit in the second connection state; and the first Raindrop detection means comprising: raindrop determination means for determining whether raindrops attached to the window glass are within a detection range on the sensor electrode based on the first or second capacitance value apparatus. A sensor electrode disposed on at least one of an upper surface of a vehicle instrument panel, an upper surface of a rear tray, and a window frame edge of a rear gate so that a detection surface exists toward the window glass;
An auxiliary electrode provided in the vicinity of the sensor electrode;
A detection circuit for detecting a capacitance value based on the capacitance from the connected electrode;
A first changeover switch capable of selectively switching between a first connection state in which the sensor electrode is connected to the detection circuit and a second connection state in which the sensor electrode is not connected to the detection circuit;
When the sensor electrode is in the first connection state, the auxiliary electrode is not connected to the detection circuit, and when the first changeover switch is in the second connection state, the auxiliary electrode is connected to the detection circuit. A switchable second changeover switch,
A comparison value comparing the first capacitance value from the detection circuit in the case of the first connection state and the second capacitance value from the detection circuit in the case of the second connection state. And raindrop determination means for determining whether or not raindrops attached to the window glass are within the detection range on the sensor electrode based on the first or second capacitance value. A raindrop detector. The first changeover switch is configured to be able to open the sensor electrode, connect to ground or a predetermined potential in the second connection state,
The raindrop detection device according to claim 5, wherein the second changeover switch is configured to be able to open, ground, or connect the auxiliary electrode to a predetermined potential in the first connection state. A shield driving circuit for giving the auxiliary electrode the same potential as the sensor electrode, or giving the sensor electrode the same potential as the auxiliary electrode,
The first changeover switch is configured to connect the sensor electrode to the shield drive circuit in the second connection state,
The raindrop detection device according to claim 5, wherein the second changeover switch is configured to be able to connect the auxiliary electrode to the shield drive circuit in the first connection state. A shield driving circuit for applying a potential equal to that of the sensor electrode to the auxiliary electrode;
The first changeover switch is configured to be able to open the auxiliary electrode in the second connection state, connect to ground or a predetermined potential,
The raindrop detection device according to claim 5, wherein the second changeover switch is configured to be able to connect the auxiliary electrode to the shield drive circuit in the first connection state. A shield driving circuit for applying a potential equal to that of the auxiliary electrode to the sensor electrode;
The first changeover switch is configured to connect the auxiliary electrode to the shield drive circuit in the second connection state,
The raindrop detection device according to claim 5, wherein the second changeover switch is configured to be able to open, ground, or connect the auxiliary electrode to a predetermined potential in the first connection state. The raindrop detection device according to claim 1, wherein the auxiliary electrode is arranged so as to surround the sensor electrode. The raindrop detection device according to any one of claims 1 to 10,
A wiper operation control device comprising: an operation control means for controlling an operation of a wiper device mounted on the vehicle based on a detection result detected by the raindrop detection device.

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