CROSS-REFERENCE TO RELATED APPLICATION

Priority is claimed on Japanese Patent Application No. 2020-069903, filed Apr. 8, 2020, the content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a motion detection device that detects a motion of a person with a capacitive sensor electrode.

Description of Related Art

As a technology of an opening and closing portion of a vehicle such as a tailgate, a device that detects a kicking motion of a person and causes the opening and closing portion to perform an opening and closing motion is known (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2018-44329). In this technology, a motion detection device equipped with a capacitive sensor electrode as a sensor that detects a motion of a person is used.

In this type of motion detection device, a plurality of sensor electrodes for detecting changes in capacitance are attached to a member attached to a vehicle body side such as a rear bumper via sensor brackets. The plurality of sensor electrodes are connected to a control unit for determining the motion of a person such as a kicking motion on the basis of the detected changes in capacitance.

SUMMARY OF THE INVENTION

In a conventional motion detection device, a plurality of sensor electrodes are disposed vertically spaced apart and the motion of a person and what is otherwise noise (for example, a noise caused by a movement of a small animal and a noise caused by water that has entered inside the attached member) are distinguished therebetween on the basis of the changes in capacitance, detected by the plurality of sensor electrodes. However, for example, when a sufficient width of separation between the plurality of sensor electrodes cannot be secured due to restrictions on the shape or size of the attached member such as a bumper, the detection accuracy (resolution) of the capacitance of each sensor electrode needs to be improved, and a small amount of water that has entered inside the attached member is easily detected as noise.

Aspects according to the present invention have been made in consideration of the circumstances described above, and an object thereof is to provide a motion detection device capable of suppressing noise from being detected by a sensor electrode due to entry of water inside an attached member.

The present invention has adopted the following aspects to solve the problems described above.

(1): A motion detection device according to one aspect of the present invention is a motion detection device that is attached to a vehicle and detects a motion of a person near the vehicle, and includes a sensor electrode configured to detect capacitance, and a sensor bracket that has a sensor holding portion holding the sensor electrode and is attached to an inner surface of an attached member attached to a vehicle body, in which the sensor holding portion includes a holding piece that extends from a side away from the inner surface to a side near to the inner surface and holds the sensor electrode, and the holding piece holds the sensor electrode at a position at which an axis of the sensor electrode is separated from the inner surface by at least 15 mm or more.

According to the aspect of (1) described above, a sensor electrode held in a holding piece of a sensor bracket is separated from an inner surface of an attached member. For this reason, even if water that has entered an inside of the attached member flows along the inner surface of the attached member, the water is less likely to directly hit the sensor electrode. Since the holding piece of a sensor bracket extends from a side away from the inner surface of the attached member to a side approaching the inner surface, the water flowing along the inner surface of the attached member is less likely to go around the sensor electrode through the holding piece. Furthermore, in the motion detection device, since an axis of the sensor electrode is separated from the inner surface of the attached member by at least 15 mm or more, the water flowing along the inner surface of the attached member is less likely to be detected as large noise by the sensor electrode.

(2): In the aspect (1) described above, the sensor holding portion may include a support block portion that has a substantially lateral square U-shaped cross section opening toward the inner surface, and a pair of holding pieces extending from a top wall of the support block portion to a side close to the inner surface and sandwiching the sensor electrode.

According to the aspect (2) described above, since the sensor electrode sandwiched between the pair of holding pieces extends from the top wall of the support block portion to an inner surface side of the attached member, it is possible to more reliably suppress water flowing along the inner surface of the attached member from going around the sensor electrode.

(3): In the aspect of (2) described above, a through hole for draining off water may be formed in a part of an area in the vicinity of the support block portion.

According to the aspect of (3) described above, water that has flowed into the peripheral area of the support block portion can be discharged from the through hole to the inner surface side of the attached member. For this reason, it is possible to suppress water from remaining around an upper surface side of the support block portion, and water from going around the sensor electrode along the support block portion and the holding piece.

(4): In the aspect of (3) described above, the through hole for draining water may also be formed at a position above the support block portion.

According to the aspect of (4) described above, the water that has flowed into the area in the vicinity of the support block portion can be discharged to the inner surface side of the attached member above the support block portion. For this reason, it is possible to more reliably suppress the water from going around the sensor electrode along the support block portion and the holding piece.

(5): In any one of the aspects (2) to (4) described above, a drainage gap is secured at a position below the support block portion between inner surface and the sensor bracket.

According to the aspect of (5) described above, water flowing along the inner surface of the attached member is discharged to a side below the sensor bracket through the drainage gap below the support block portion. For this reason, it is possible to prevent water from staying in an area of the inner surface of the attached member, which faces the sensor electrode.

(6): In any one of the aspects (1) to (5) described above, the holding piece may be formed such that the held sensor electrode faces a portion of the inner surface, which is inclined with respect to a horizontal direction.

According to the aspect of (6) described above, even if the water that has entered the inside of the attached member flows into a position facing the sensor electrode along the inner surface, since this portion is inclined with respect to the horizontal direction, the water can be quickly discharged below the sensor electrode.

(7) In the aspect of (2) described above, the pair of holding pieces may also be formed such that a width of separation between each other narrows from a side away from the inner surface to a side approaching the inner surface.

According to the aspect of (7) described above, when the sensor electrode is attached to the holding pieces, the sensor electrode may be disposed at a position with a wide width of separation between the holding pieces, and the sensor electrode may be caused to slide to a position with a narrow width of separation between the holding pieces in this state. As a result, it is possible to easily attach the sensor electrode to the holding pieces.

(8): In the aspect of (7) described above, the attached member may be a bumper extending in a vehicle width direction, the sensor bracket may have a plurality of sensor holding portions disposed in an extending direction of the bumper, and the sensor electrode may be formed to be longest along the extending direction of the bumper and may be sandwiched between the holding pieces of the plurality of sensor holding portions.

According to the aspect of (8) described above, a long sensor electrode can be held in the plurality of sensor holding portions of the sensor bracket. When the sensor electrode is attached to the sensor bracket, the sensor electrode can be disposed at a position with a wide width of separation between the holding pieces of each sensor holding portion and the sensor electrode can be caused to slide to a position with a narrow width of separation between the holding pieces of each sensor holding portion in this state. As a result, it is possible to easily attach a long sensor electrode to the sensor bracket.

According to the aspects of the present invention, it is possible to suppress noise from being detected by a sensor electrode due to entry of water inside an attached member.

