JP6907501B2 - Electrostatic sensor - Google Patents

Description

The present invention relates to an electrostatic sensor.

Electrostatic sensors that detect the presence or absence of the approach of the human body through changes in capacitance are well known.
The electrostatic sensor of 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. To be equipped. The monitoring unit monitors each detection signal output by 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 by the second sensor.

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

JP-A-2015-290167

In general, the electrostatic capacity of an electrostatic sensor is likely to change due to rain, water, or the like, and therefore, when it is exposed to water, it may erroneously detect that a human body has approached. However, as described above, since the electrostatic sensor of Patent Document 1 has a configuration that suppresses erroneous detection of approach of the human body due to wireless communication, 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, the electrostatic sensor uses the first electrode, the second electrode having a larger area than the first electrode, and the first electrode and the second electrode to have a capacitance at a long distance. A switching unit that switches 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 change in capacitance in the second electrode in the low-sensitivity mode. A determination unit for determining a water-wet state when the amount is larger than the amount of change in capacitance in the first electrode in the low-sensitivity mode is provided , and the determination unit includes the first electrode in the high-sensitivity mode. Based on the amount of change in capacitance and the amount of change in capacitance in the second electrode in the high-sensitivity mode, a normal mode for determining the presence or absence of approaching conductors and a non-judgment mode for determining whether or not the conductors are approaching The normal mode is switched to the non-judgment mode triggered by the determination of the wet state .

Generally, in an electrostatic sensor, a detection range is set. The detection range can be set as appropriate, but if the detection range is set to a short distance, the approach of the hand cannot be detected unless the hand is sufficiently close, and if the detection range is set to a long distance, , There is a risk of erroneous detection if the product is wet with a water film.

In that respect, according to this configuration, the first electrode has a low-sensitivity mode for detecting a change in capacitance at a short distance, and the amount of change in capacitance in the second electrode having a large area in the low-sensitivity mode is small in area. If it is larger than the amount of change in capacitance in, it is judged to be in a wet state. This makes it possible to preferably determine whether or not the product is wet. Therefore, erroneous detection due to water wetting is suppressed. In addition, since it also has a high-sensitivity mode, it is easy to determine whether or not a hand is approaching.

According to the above configuration, in a device that operates based on the detection result of the electrostatic sensor, the operation based on the false detection of the electrostatic sensor is suppressed.
In the above configuration, it is preferable that the determination unit determines that the second electrode is in a water-wetting state when the amount of change in capacitance in the second electrode exceeds a preset water-wetting 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 configuration, the determination unit sets the 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. If it exceeds, it is preferable to determine that the state is wet.

According to this configuration, it is possible to determine the presence or absence of a water-wet state excluding the case of momentary water-wetness .

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

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

Hereinafter, an embodiment of the 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 such as 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 includes a first electrode 11, a second electrode 12, a drive electrode 13, a ground electrode 14, an electrode substrate 15, and a control substrate 16, and each of these configurations is accommodated. A case 17 is provided.

The case 17 has a first accommodating portion 71 that opens outward. The first accommodating portion 71 has an elliptical shape that is longer in the left-right direction than in the up-down direction in the front view (FIG. 3). A first cover 18 that closes the first accommodating portion 71 and is exposed to the outside is attached to the case 17. An emblem for identifying a vehicle type, a vehicle manufacturer, or the like may be attached to the first cover 18. 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 accommodating portion 72 that opens back to back with the first accommodating portion 71, that is, toward the inside. The opening area of the second accommodating portion 72 is set smaller than the opening area of the first accommodating portion 71. A second cover 19 that closes the second accommodating portion 72 is attached to the case 17.

It is desirable that the case 17, the first cover 18, and the second cover 19 are made of a resin or the like that does not easily affect the capacitance. Further, when the emblem is attached to the first cover 18, it is desirable that the emblem is also made of a resin or the like that does not easily affect 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 arranged on the outer surface 15a and the ground electrode 14 arranged 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 accommodating portion 72.
The electrode substrate 15 and the control substrate 16 are electrically connected by a connecting line 20. Further, the control board 16 includes a connector terminal 22 extending to the connector portion 21 provided on the side portion of the second accommodating portion 72. The connector portion 21 is a portion connected to a vehicle-mounted connector (not shown). The control board 16 is electrically connected to the vehicle-mounted ECU 3 (see FIGS. 1 and 4) via the connector terminal 22.

As shown in FIG. 2, the first electrode 11 has a semicircular outer periphery curved so as to gently bulge upward along the upper edge portion of the electrode substrate 15, and is paired downward with the outer periphery. It is a spindle-shaped electrode whose left-right end surrounded by a semicircular outer periphery curved so as to bulge is sharpened, and is attached to the upper part of the electrode substrate 15.

The second electrode 12 is a semicircular 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 to be larger than the area of the first electrode 11. Further, 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). Therefore, the area adjacent to the steel plate of the back door (not shown) on which the electrostatic sensor 10 is provided is set to be larger in the second electrode 12 than in the first electrode 11.

The drive electrode 13 is attached to the central portion of the electrode substrate 15 in the vertical direction so as to be sandwiched 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 secure insulation between the two adjacent electrodes. The gap 23 may be replaced with an insulating material.

The electrostatic sensor 10 is a mutual capacitance type electrostatic sensor that allows 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 a conductor based on the amount of change in capacitance between the first electrode 11 and the second electrode 12 when a part of the human body or a conductor such as water is close to the electrostatic sensor 10. Judgment such as proximity and water wetting is carried out.

The ground electrode 14 contributes to an increase in capacitance at each electrode as compared with the case where it is not provided. Therefore, it contributes to an increase in the amount of change in capacitance when the 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 detection range is set so that the proximity of the conductor at a relatively long distance (for example, 10 mm or more and 30 mm or less) can be easily detected. It switches between a low sensitivity mode and a detection range that makes it easy to detect the proximity of conductors 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 of the high-sensitivity mode and the detection range of the low-sensitivity mode overlap. In this example, the range of the distance detected in the high-sensitivity mode and the range of the distance detected in the low-sensitivity mode are separated based on the distance of 10 mm from the electrode. The reference distance for carving can be changed as appropriate.

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

The operation determination condition C1, the erroneous detection suppression condition C2, and the return condition C3 are stored in the memory 62 in advance.
Further, the control ECU 61 determines whether or not each of the operation determination condition C1, the erroneous detection suppression condition C2, and the return condition C3 is satisfied, and the normal mode for generating various signals and whether or not each condition is satisfied. It has a signal generation stop mode that determines whether or not, but 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 so that the capacitance change amount S1 does not exceed 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, or 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 in which the user brings his / her hand close to the electrostatic sensor 10, and generates an operation signal which is an electric signal to that effect. The operation signal is sent to the in-vehicle ECU 3. When the in-vehicle ECU 3 recognizes the approach determination signal while the back door 2 is locked, the in-vehicle ECU 3 unlocks the back door 2.

In the erroneous detection suppression condition C2, the capacitance change amount S4 is larger than the capacitance change amount S3, and the capacitance change amount S4 exceeds the erroneous detection suppression determination threshold value T3. It is set to last only the false detection suppression duration T11.

S4> S3, S4> T3, and T11 continued ... C2
As shown in FIG. 6, when the false 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. The control ECU 61 monitors the change in capacitance at each electrode even while the signal generation stop mode is set. The control ECU 61 does not generate an operation signal even if the operation determination condition C1 is satisfied while the signal generation stop mode is set. That is, the signal generation stop mode corresponds to the non-determination mode.

In the return condition C3, the capacitance change amount S1 is less than the return determination threshold value T5, and the capacitance change amount S2 is less than the return determination threshold value T6. It is set to continue.

S1 <T5, S2 <T6, and T12 continued ... C3
When the return condition C3 is satisfied in the signal generation stop mode, the control ECU 61 determines that the state in which the electrostatic sensor 10 is covered with the water film has been resolved, 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 has a high-sensitivity mode for detecting the amount of change in capacitance of each electrode at a long distance from the electrostatic sensor 10 more accurately from the first electrode 11 and the second electrode 12. , Switch to the low sensitivity mode for detecting the amount of change in capacitance of each electrode at a relatively short distance. Then, when the erroneous detection suppression condition C2 is satisfied, the control ECU 61 is configured so as to shift from the normal mode to the signal generation stop mode and not to generate an operation signal.

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. It is defined as the amount. Further, the second electrode 12 has a larger area than the first electrode 11. Therefore, when the electrostatic sensor 10 is covered with a water film, the amount of change in capacitance of the second electrode 12 is larger than that of the first electrode 11. Therefore, according to the electrostatic sensor 10, it is possible to preferably determine whether or not the patient is in a water-wet state covered with a water film. That is, the electrostatic sensor 10 has an effect of suppressing erroneous detection due to water wetting.

As shown in FIG. 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. Yes (L2> L1). Therefore, the area adjacent to the steel plate of the back door (not shown) on which the electrostatic sensor 10 is provided is larger in the second electrode 12 than in the first electrode 11. This point also contributes to the fact that when the electrostatic sensor 10 is covered with a water film, the amount of change in capacitance of the second electrode 12 is larger than that of the first electrode 11.

The false detection suppression condition C2 includes a conditional expression that the capacitance change amount S4 exceeds the false detection suppression determination threshold value T3. As a result, in a situation where a small amount of water droplets adhere to the electrostatic sensor 10, it is not determined to be in a wet state. Therefore, according to the electrostatic sensor 10, it is possible to more preferably determine whether or not the patient is in a water-wet state covered with a water film.

Further, under the erroneous detection suppression condition C2, the capacitance change amount S4 is larger than the capacitance change amount S3, and the capacitance change amount S4 exceeds the erroneous detection suppression determination threshold value T3. A time condition is included in which the established state lasts for the erroneous detection suppression duration T11.

As a result, in a situation where the electrostatic sensor 10 is momentarily covered with a water film, it is not determined to be in a water-wet state. In other words, according to the electrostatic sensor 10, it is possible to suitably determine whether or not the water-wet state such that the water film is covered continues.

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

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

According to this example, not only the wet state but also 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 suppressed.
The above embodiment may be changed as follows.

-In the above embodiment, the time condition may be omitted from the false 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 the 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.

When the second electrode 12 is provided on the lower side of the first electrode 11, more precisely on the lower side in the direction of gravity as in the above embodiment, the second electrode 12 becomes wet with water rather than the first electrode 11. Since it is easy, it is easier to detect the wet state than other positional relationships, and it is easy to suppress the malfunction of the in-vehicle device.

-In the above embodiment, the shape of each electrode including the first electrode 11 and the second electrode 12 can be changed as appropriate. 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 the above embodiment, the in-vehicle ECU 3 uses the detection result of the electrostatic sensor 10 for unlocking the back door 2, but it may be used for other purposes. For example, when the back door 2 is a power back door that opens and closes electrically, it may be used as a trigger for opening / closing operation. Further, it may be used as a trigger for locking and unlocking at other doors of the back door 2.

-In the above embodiment, the control ECU 61 may directly control the in-vehicle device.
Next, the technical idea recalled from the above embodiment and the above alternative example 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, as the return condition, the amount of change in capacitance of the first electrode in the high-sensitivity mode and the amount of change in capacitance of the second electrode in the high-sensitivity mode are set in advance. The case is below the return judgment threshold.

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 substrate, 16 ... Control Board, 17 ... Case, 18, 19 ... Cover, 20 ... Connection line, 21 ... Connector part, 22 ...
Connector terminal, 23 ... Gap, 61 ... Control ECU (switching unit, determination unit), 62 ... Memory, 71 ... 1st accommodating unit, 72 ... 2nd accommodating unit.

Claims (3)

With the first electrode
A second electrode having a larger area than the first electrode and
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. Switching part and
A determination unit for determining a water-wet state when the amount of change in capacitance of the second electrode in the low-sensitivity mode is larger than the amount of change in capacitance of the first electrode in the low-sensitivity mode is provided. ,
The determination unit determines whether or not the conductor is approaching based on the amount of change in capacitance of the first electrode in the high-sensitivity mode and the amount of change in capacitance of the second electrode in the high-sensitivity mode. An electrostatic sensor that has a non-judgment mode that does not determine whether or not a conductor is approaching, and switches from the normal mode to the non-judgment mode triggered by the determination of the wet state. In the electrostatic sensor according to claim 1,
The determination unit is an electrostatic sensor that determines a water-wetting state when the amount of change in capacitance at the second electrode exceeds a preset water-wetting determination threshold. In the electrostatic sensor according to claim 1 or 2.
The determination unit is in a state where at least the amount of change in capacitance in the second electrode in the low sensitivity mode is larger than the amount of change in capacitance in the first electrode in the low sensitivity mode exceeds the set time. An electrostatic sensor that determines that the product is wet.

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