JP2018063181A - Electrostatic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic sensor capable of preventing erroneous detection due to water wetting.SOLUTION: An electrostatic sensor 10 includes: a first electrode 11; a second electrode 12 having an area larger than that of the first electrode 11; and a control ECU that switches over the respective electrodes between a high sensitivity mode for detecting a change in capacitance at a far distance and a low sensitivity mode for detecting a change in capacitance at a near distance. The control ECU functions also as a determination part that determines a state to be a water wetting state when a capacitance change amount in the second electrode 12 in the low sensitivity mode is larger than a capacitance change amount in the first electrode 11.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electrostatic sensor.

2. Description of the Related Art An electrostatic sensor that detects whether a human body is approaching or not is known through a change in capacitance.
The electrostatic sensor disclosed in Patent Document 1 includes a first sensor that outputs a detection signal according to a change in capacitance, a second sensor that outputs a detection signal according to a transmission wave transmitted from an antenna, and a monitoring unit. Is provided. The monitoring unit monitors each detection signal output from the first sensor and the second sensor, and prohibits the output from the first sensor for a set time according to the detection signal output from the second sensor.

  In the electrostatic sensor disclosed in Patent Document 1, a transmission wave transmitted from an antenna is for performing wireless communication with an electronic key possessed by a vehicle user. That is, the electrostatic sensor disclosed in Patent Document 1 suppresses erroneous detection of human approach due to wireless communication between the vehicle and the electronic key.

Japanese Patent Laid-Open No. 2015-200617

  Generally, an electrostatic sensor is likely to change its capacitance due to rain, water, or the like, and therefore may erroneously detect that a human body has approached due to water. However, as described above, the electrostatic sensor disclosed in Patent Document 1 is configured to suppress erroneous detection of human approach due to wireless communication, and thus erroneous detection due to water wetting is not suppressed.

  An object of the present invention is to provide an electrostatic sensor that suppresses erroneous detection due to water wetting.

  In order to solve the above problems, an electrostatic sensor includes a first electrode, a second electrode having a larger area than the first electrode, the first electrode, and the second electrode. A switching unit for switching between a high sensitivity mode for detecting a change and a low sensitivity mode for detecting a change in capacitance at a short distance; and a capacitance change in the second electrode in the low sensitivity mode A gist is provided with a determination unit that determines a wet state when the amount is larger than the amount of change in capacitance of the first electrode in the low sensitivity mode.

  Generally, in an electrostatic sensor, a detection range is set. The detection range can be set as appropriate, but when the detection range is set to a short distance, the approach of the hand cannot be detected unless the hand is sufficiently approached, and when the detection range is set to a long distance If the water film is so wet that the water film is stretched, there is a risk of false detection.

  In this regard, according to this configuration, the first electrode has a low sensitivity mode for detecting a change in capacitance at a short distance, and the capacitance change amount in the second electrode having a large area in the low sensitivity mode has a small area. If it is larger than the amount of change in electrostatic capacity, the water wet state is determined. Thereby, it can be determined suitably whether it is in a wet state. Accordingly, erroneous detection due to water wetting is suppressed. Also, since it has a high sensitivity mode, it is easy to determine whether or not the hand is approaching.

The said structure WHEREIN: It is preferable to determine with the said determination part being a wet state, when the electrostatic capacitance variation | change_quantity in a said 2nd electrode exceeds the preset water wet determination threshold value.
According to this configuration, it is possible to more accurately determine the presence or absence of a wet state.

  In the above-described configuration, the determination unit has a set time when at least the capacitance change amount in the second electrode in the low sensitivity mode is larger than the capacitance change amount in the first electrode in the low sensitivity mode. When exceeding, it is preferable to determine with a wet state.

According to this configuration, it is possible to determine the presence or absence of a wet state excluding the case of instantaneous water wet.
In the above configuration, the determination unit determines whether or not a conductor is approaching based on a capacitance change amount of the first electrode in the high sensitivity mode and a capacitance change amount in the second electrode of the high sensitivity mode. It is preferable to have a normal mode for determination and a non-determination mode in which the presence / absence of the approach of the conductor is not determined, and switching from the normal mode to the non-determination mode triggered by the determination of the wet state.

  According to this configuration, in the device that operates based on the detection result of the electrostatic sensor, the operation based on the erroneous detection of the electrostatic sensor is suppressed.

  The electrostatic sensor of the present invention can suppress erroneous detection due to water wetting.

The perspective view of a vehicle rear part. The front view of an electrostatic sensor. FIG. 3 is a cross-sectional view taken along a cross-section indicating line 3-3 in FIG. 2. The block diagram which shows the electrical schematic structure of an electrostatic sensor. The graph which shows the relationship between the detection range and distance in low sensitivity mode and high sensitivity mode. The time chart which shows the change of an electrostatic capacitance change amount and time, and the switching of the mode in control ECU.

Hereinafter, an embodiment of an electrostatic sensor will be described with reference to the drawings.
As shown in FIG. 1, an electrostatic sensor 10 is provided on the back door 2 of the vehicle 1. The electrostatic sensor 10 is connected to the in-vehicle ECU 3, and the in-vehicle ECU 3 executes control of various in-vehicle devices including unlocking the back door 2 based on the detection result of the electrostatic sensor 10.

  As shown in FIGS. 2 and 3, the electrostatic sensor 10 houses the first electrode 11, the second electrode 12, the drive electrode 13, the ground electrode 14, the electrode substrate 15, and the control substrate 16, and each of these components. Case 17 is provided.

  The case 17 has the 1st accommodating part 71 opened toward the exterior. The first accommodating portion 71 has an elliptical shape that is longer in the left-right direction than in the up-down direction when viewed from the front (FIG. 3). The case 17 is provided with a first cover 18 that closes the first accommodating portion 71 and is exposed to the outside. The first cover 18 may be attached with an emblem for specifying a vehicle type, a vehicle manufacturer, and the like. The vertical direction corresponds to the gravity direction, and the horizontal direction corresponds to the vehicle width direction.

  In addition, the case 17 has a second housing portion 72 that opens back to back with the first housing portion 71, that is, toward the inside. The opening area of the second housing part 72 is set smaller than the opening area of the first housing part 71. A second cover 19 that closes the second housing portion 72 is attached to the case 17.

  Note that the case 17, the first cover 18, and the second cover 19 are desirably formed of a resin that does not easily affect the capacitance. In addition, when the emblem is attached to the first cover 18, it is desirable that the emblem is also formed of a resin or the like that hardly affects the capacitance.

  The electrode substrate 15 is attached to the first accommodating portion 71 with the first electrode 11, the second electrode 12, and the drive electrode 13 being disposed on the outer surface 15a, and the ground electrode 14 being disposed on the inner surface 15b. . The electrode substrate 15 has an elliptical shape similar to that of the first accommodating portion 71.

The control board 16 is a board on which the control ECU 61 (see FIG. 4) is provided, and is attached to the second housing portion 72.
The electrode substrate 15 and the control substrate 16 are electrically connected by a connection line 20. The control board 16 includes a connector terminal 22 that extends to the connector portion 21 provided on the side portion of the second housing portion 72. The connector part 21 is a part connected to an in-vehicle connector (not shown). The control board 16 is electrically connected to the in-vehicle ECU 3 (see FIGS. 1 and 4) via the connector terminal 22.

  As shown in FIG. 2, the first electrode 11 has a semicircular arc outer periphery that curves so as to gently bulge upward along the upper edge of the electrode substrate 15, and the lower side in a manner that forms a pair with this. A spindle-shaped electrode surrounded by a semicircular arc-shaped outer periphery that curves so as to swell and has a sharp end, and is attached to the upper portion of the electrode substrate 15.

  The second electrode 12 is a semicircular arc-like electrode that gently curves along the lower edge of the electrode substrate 15, and is attached along the lower edge of the electrode substrate 15. In the front view (FIG. 1), the area of the second electrode 12 is set larger than the area of the first electrode 11. The dimension L2 of the outer periphery 12a along the lower edge of the electrode substrate 15 in the second electrode 12 is set longer than the dimension L1 of the outer periphery 11a along the upper edge of the electrode substrate 15 in the first electrode. (L1> L2). For this reason, the adjacent area with respect to the steel plate of the back door (not shown) in which the electrostatic sensor 10 is provided is set so that the second electrode 12 is larger than the first electrode 11.

The drive electrode 13 is attached to the center of the electrode substrate 15 in the vertical direction in such a manner that the drive electrode 13 is provided between the first electrode 11 and the second electrode 12 in the vertical direction.
A gap 23 is provided between the first electrode 11 and the drive electrode 13 and between the drive electrode 13 and the second electrode 12 in order to ensure insulation between the two adjacent to each other. The gap 23 may be replaced with an insulating material.

  The electrostatic sensor 10 is a mutual capacitive electrostatic sensor that causes the first electrode 11 and the second electrode 12 to receive an electric field formed through the drive electrode 13. The control ECU 61 provided on the control board 16 is based on the amount of change in capacitance in the first electrode 11 and the second electrode 12 when a part of the human body or a conductor such as water comes close to the electrostatic sensor 10. Judgment of proximity and water wetting etc.

  In addition, compared with the case where the ground electrode 14 is not provided, it contributes to the increase in the electrostatic capacitance in each electrode. Therefore, it contributes to an increase in the amount of change in capacitance when a conductor is close to the electrostatic sensor 10.

Next, the control ECU 61 provided on the control board 16 will be described.
As shown in FIG. 4, the control ECU 61 adjusts the strength of the electric field formed through the drive electrode 13 by adjusting the signal level supplied to the drive electrode 13. Through the adjustment, the control ECU 61 compares the first electrode 11 and the second electrode 12 with the high sensitivity mode in which the proximity of the conductor at a relatively far distance (for example, 10 mm to 30 mm) is easily detected. The mode is switched to the low sensitivity mode in which the detection range is easy to detect the proximity of the conductor at a short distance (for example, less than 10 mm). That is, the control ECU 61 functions as a switching unit.

  As shown in FIG. 5, the detection range in the high sensitivity mode and the detection range in the low sensitivity mode overlap. In this example, the distance range detected in the high sensitivity mode and the distance range detected in the low sensitivity mode are separated based on the distance of 10 mm from the electrode. It should be noted that the reference distance for separation can be changed as appropriate.

The control ECU 61 periodically switches the first electrode 11 and the second electrode 12 between a high sensitivity mode and a low sensitivity mode.
Here, the capacitance change amount S1 when the first electrode 11 is in the high sensitivity mode, the capacitance change amount S2 when the second electrode 12 is in the high sensitivity mode, and the first electrode 11 in the low sensitivity mode. The capacitance change amount S3 is defined as the capacitance change amount S4 when the second electrode 12 is in the low sensitivity mode. The control ECU 61 generates various signals when the capacitance variation amounts S1, S2, S3, and S4 satisfy the conditions stored in the memory 62. That is, the control ECU 61 functions as a determination unit.

In the memory 62, an operation determination condition C1, an erroneous detection suppression condition C2, and a return condition C3 are stored in advance.
Further, the control ECU 61 determines whether or not the operation determination condition C1, the erroneous detection suppression condition C2, and the return condition C3 are satisfied, and generates a variety of signals, and whether or not the conditions are satisfied. A signal generation stop mode that does not generate various signals. The control ECU 61 switches between the normal mode and the signal generation stop mode depending on whether or not each condition is satisfied.

  The operation determination condition C1 is set such that the capacitance change amount S1 exceeds the first operation determination threshold value T1 and the capacitance change amount S2 does not exceed the second operation determination threshold value T2. The first operation determination threshold value T1 and the second operation determination threshold value T2 are set based on a simulator, an experiment, and the like, respectively.

S1> T1 and S2> T2... C1
When the operation determination condition C1 is satisfied, the control ECU 61 determines that the user has performed an operation of bringing the hand closer to the electrostatic sensor 10, and generates an operation signal that is an electrical signal indicating that. The operation signal is sent to the in-vehicle ECU 3. The in-vehicle ECU 3 unlocks the back door 2 when the approach determination signal is recognized in a state where the back door 2 is locked.

  The erroneous detection suppression condition C2 is that the capacitance change amount S4 is larger than the capacitance change amount S3, the capacitance change amount S4 exceeds the erroneous detection suppression determination threshold value T3, and these two determination establishment states are satisfied. It is set to continue only for the erroneous detection suppression duration T11.

S4> S3, S4> T3, and T11 continuation ... C2
As shown in FIG. 6, when the erroneous detection suppression condition C2 is satisfied, the control ECU 61 determines that the electrostatic sensor 10 is covered with a water film, and shifts from the normal mode to the signal generation stop mode. Note that the control ECU 61 monitors the change in capacitance at each electrode even in the signal generation stop mode. While in the signal generation stop mode, the control ECU 61 does not generate an operation signal even if the operation determination condition C1 is satisfied. That is, the signal generation stop mode corresponds to a non-determination mode.

  The return condition C3 is that the capacitance change amount S1 is less than the return determination threshold value T5, the capacitance change amount S2 is less than the return determination threshold value T6, and these two determination establishment states are only the return determination time T12. It is set to continue.

S1 <T5 and S2 <T6, and T12 continues ... C3
When the return condition C3 is satisfied in the signal generation stop mode, the control ECU 61 determines that the state where the electrostatic sensor 10 is covered with the water film has been eliminated, and shifts from the signal generation stop mode to the normal mode.

Next, the operation and effect of the electrostatic sensor 10 will be described.
The control ECU 61 detects a capacitance change amount of each electrode at a long distance from the electrostatic sensor 10, more precisely, from the first electrode 11 and the second electrode 12, and The low sensitivity mode for detecting the capacitance change amount of each electrode at a relatively close distance is switched. Then, when the erroneous detection suppression condition C2 is satisfied, the control ECU 61 is configured not to generate an operation signal by shifting from the normal mode to the signal generation stop mode.

The false detection suppression condition C2 includes a conditional expression that the capacitance change amount S4 exceeds the capacitance change amount S3.
Here, the capacitance change amount S3 is defined as the capacitance change amount of the first electrode 11 in the low sensitivity mode, and the capacitance change amount S4 is the capacitance change of the second electrode 12 in the low sensitivity mode. The amount is specified. The second electrode 12 has a larger area than the first electrode 11. For this reason, when the electrostatic sensor 10 is covered with a water film, the capacitance change amount of the second electrode 12 is larger than that of the first electrode 11. Therefore, according to this electrostatic sensor 10, it can be suitably determined whether or not it is in a water-wetting state covered with a water film. That is, the electrostatic sensor 10 has an effect that erroneous detection due to water wetting is suppressed.

  2, the dimension L2 of the outer periphery 12a along the lower edge of the second electrode 12 is set longer than the dimension L1 of the outer periphery 11a along the upper edge of the first electrode 11. (L2> L1). For this reason, the adjacent area with respect to the steel plate of the back door (not shown) where the electrostatic sensor 10 is provided is larger in the second electrode 12 than in the first electrode 11. This also contributes to the fact that the second electrode 12 has a larger capacitance variation than the first electrode 11 when the electrostatic sensor 10 is covered with a water film.

  The erroneous detection suppression condition C2 includes a conditional expression that the capacitance change amount S4 exceeds the erroneous detection suppression determination threshold T3. Thus, in a situation where a small amount of water droplets are attached to the electrostatic sensor 10, it is not determined that the water is wet. Therefore, according to the electrostatic sensor 10, it is possible to more suitably determine whether or not the water wet state is covered with a water film.

  Further, in the false detection suppression condition C2, the electrostatic capacity change amount S4 is larger than the electrostatic capacity change amount S3, and the electrostatic capacity change amount S4 exceeds the false detection suppression determination threshold value T3. A time condition that the established state lasts for the erroneous detection suppression continuation time T11 is included.

  Thereby, in the situation where the electrostatic sensor 10 is instantaneously covered with the water film, it is not determined that the water is wet. In other words, according to the electrostatic sensor 10, it can be suitably determined whether or not the water wet state that is covered by the water film continues.

  Since the control ECU 61 shifts from the normal mode to the signal generation stop mode and does not generate an operation signal when the erroneous detection suppression condition C2 is satisfied, the in-vehicle ECU 3 operates based on the erroneous detection of the electrostatic sensor 10. It is suppressed.

  Further, even in the signal generation stop mode, the control ECU 61 monitors the change in the capacitance of each electrode, and when the return condition C3 is satisfied, the control ECU 61 returns from the signal generation stop mode to the normal mode. Thereby, the electrostatic sensor 10 can detect a user's operation and can operate a vehicle-mounted apparatus (here, the back door 2 is unlocked) in connection with cancellation | release of a wet state.

In addition, according to this example, the malfunction of the in-vehicle device due to the so-called door leaning state in which the user leans against the door so as to cover the electrostatic sensor 10 is not limited to the wet state.
In addition, you may change the said embodiment as follows.

In the above embodiment, the time condition may be omitted from the erroneous detection suppression condition C2.
In the above embodiment, the condition that the capacitance change amount S4 exceeds the erroneous detection suppression determination threshold value T3 may be omitted from the erroneous detection suppression condition C2.

In the above embodiment, the return condition C3 may be replaced with a condition that the false detection suppression condition C2 is not satisfied.
In the above embodiment, the first electrode 11 and the second electrode 12 are provided adjacent to each other in the vertical direction, but the positional relationship can be changed as appropriate.

  If the second electrode 12 is provided on the lower side of the first electrode 11, more precisely on the lower side in the gravitational direction as in the above embodiment, the second electrode 12 becomes wetter than the first electrode 11. Since it is easy, compared with other positional relationships, it is easier to detect the wet state, and malfunction of the in-vehicle device is also easily suppressed.

  -In the said embodiment, the shape of each electrode including the 1st electrode 11 and the 2nd electrode 12 can be changed suitably. Further, the shapes of the electrode substrate 15 and the control substrate 16 can be changed as appropriate. Furthermore, the shape of the case 17 can be changed as appropriate.

  -In above-mentioned embodiment, although vehicle-mounted ECU3 utilized the detection result of the electrostatic sensor 10 for unlocking the back door 2, you may use it for another use. For example, when the back door 2 is a power back door that is opened and closed electrically, the back door 2 may be used as a trigger for opening and closing operations. Moreover, you may use for the trigger of locking and unlocking in the other door of the back door 2. FIG.

In the above embodiment, the control ECU 61 may directly control the in-vehicle device.
Next, the technical idea conceived from the embodiment and the other examples will be described.
(A) In the above configuration, the determination unit returns from the non-determination mode to the normal mode when a preset return condition is satisfied.

  (B) In the above configuration, the return condition is set in advance such that a capacitance change amount in the first electrode in the high sensitivity mode and a capacitance change amount in the second electrode in the high sensitivity mode are set in advance. It is a case that falls below the return judgment threshold.

DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Back door, 3 ... In-vehicle ECU, 10 ... Electrostatic sensor, 11 ... 1st electrode, 12 ... 2nd electrode, 13 ... Drive electrode, 14 ... Ground electrode, 15 ... Electrode board, 16 ... Control Board, 17 ... Case, 18, 19 ... Cover, 20 ... Connection line, 21 ... Connector, 22 ...
Connector terminal, 23 ... gap, 61 ... control ECU (switching unit, determination unit), 62 ... memory, 71 ... first housing part, 72 ... second housing part.

Claims (4)

A first electrode;
A second electrode having a larger area than the first electrode;
The first electrode and the second electrode are switched between a high sensitivity mode for detecting a change in capacitance at a long distance and a low sensitivity mode for detecting a change in capacitance at a short distance. A switching unit;
A determination unit that determines a wet state when a capacitance change amount in the second electrode in the low sensitivity mode is larger than a capacitance change amount in the first electrode in the low sensitivity mode. Electrostatic sensor. The electrostatic sensor according to claim 1,
The determination unit is an electrostatic sensor that determines a wet state when the amount of change in capacitance in the second electrode exceeds a preset water wetness determination threshold. The electrostatic sensor according to claim 1 or 2,
When the state where the capacitance change amount in the second electrode in the low sensitivity mode is larger than the capacitance change amount in the first electrode in the low sensitivity mode exceeds a set time, the determination unit, An electrostatic sensor that determines that the product is wet. In the electrostatic sensor according to any one of claims 1 to 3,
The determination unit is configured to determine whether or not a conductor is approaching based on a capacitance change amount of the first electrode in the high sensitivity mode and a capacitance change amount in the second electrode in the high sensitivity mode. And a non-determination mode that does not determine whether or not the conductor is approaching, and that switches from the normal mode to the non-determination mode triggered by the determination of the wet state.

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