US-12627072-B2 - Vehicle wireless device

US12627072B2US 12627072 B2US12627072 B2US 12627072B2US-12627072-B2

Abstract

A vehicle wireless device is used in a state being attached to an attachment surface of a vehicle. A circuit board includes a circuit that transmits or receives a radio wave at a predetermined target frequency. An antenna includes a board parallel portion parallel to the circuit board to receive a horizontally polarized wave having a vibration direction of an electric field parallel to the circuit board. A case accommodates the circuit board and the antenna. The circuit board faces the attachment surface when the vehicle wireless device is attached to the attachment surface. The circuit board may have a board region overlapping the board parallel portion without a conductor plate being provided in the board region. An inner space of the case may have a case region extending by λ/4 downward from the board parallel portion without a conductor plate being provided in the case region.

Inventors

Youhei SEKIYA
Kenichiro Sanji
Takashi Saiki

Assignees

DENSO CORPORATION

Dates

Publication Date: 20260512
Application Date: 20231117
Priority Date: 20210622

Claims (10)

1 . A vehicle wireless device configured to be attached to an attachment surface of a vehicle, the device comprising: a circuit board including a dielectric and a circuit configured to transmit or receive a radio wave at a predetermined target frequency of 700 MHz or more; a horizontally polarized wave antenna configured to receive the radio wave and including a board parallel portion parallel to the circuit board to receive a board horizontally polarized wave having a vibration direction of an electric field parallel to the circuit board; and a case accommodating the circuit board and the horizontally polarized wave antenna, wherein the circuit board is arranged such that the circuit board faces the attachment surface of the vehicle when the vehicle wireless device is attached to the attachment surface, the circuit board has a board region overlapping the board parallel portion without a ground portion being formed in the board region, the ground portion is a conductor plate configured to provide a ground potential for the circuit, a bottom of the case has a facing portion that faces the board parallel portion and at least the facing portion is made of resin, the board parallel portion is arranged such that the board parallel portion is at a distance of λ/4 or more from a vehicle body of the vehicle when the vehicle wireless device is attached to the attachment surface, λ is a wavelength of the radio wave, a side surface of the case has a marker that is a line indicating a position of the board parallel portion provided within the case, and the board region of the circuit board and the bottom of the case face each other without a metal plate positioned between the board region and the bottom of the case.
2 . The vehicle wireless device according to claim 1 , wherein the antenna further includes an upright portion standing from the circuit board, and the antenna has a three-dimensional shape in which the board parallel portion is connected to the upright portion at an upper end portion of the upright portion.
3 . The vehicle wireless device according to claim 2 , wherein the antenna is an L-shaped antenna or an F-shaped antenna.
4 . The vehicle wireless device according to claim 1 , further comprising: a support portion made of resin having a predetermined thickness and disposed on an upper surface of the circuit board, wherein the board parallel portion is provided on a surface of the support portion or inside the support portion.
5 . The vehicle wireless device according to claim 1 , further comprising: a vertically polarized wave antenna configured to receive a board vertically polarized wave having a vibration direction of an electric field perpendicular to the circuit board.
6 . The vehicle wireless device according to claim 5 , wherein a lower surface or inside of the circuit board has a ground portion being a conductor plate configured to provide a ground potential for the circuit, the vertically polarized wave antenna includes a facing conductor plate being a conductor member having a plate shape and provided at a predetermined interval from the ground portion, the facing conductor plate having a feeding point, and a short-circuit portion provided in a central region of the facing conductor plate and configured to electrically connect the facing conductor plate and the ground portion, and the vertically polarized wave antenna is configured to create parallel resonance at the target frequency using an inductance of the short-circuit portion and a capacitance between the ground portion and the facing conductor plate.
7 . The vehicle wireless device according to claim 1 , wherein the horizontally polarized wave antenna is one of horizontally polarized wave antennas, and the horizontally polarized wave antennas are arranged in a predetermined direction.
8 . A vehicle wireless device configured to be attached to an attachment surface of a vehicle, the device comprising: a circuit board including a dielectric and a circuit configured to transmit or receive a radio wave at a predetermined target frequency of 700 MHz or more; a horizontally polarized wave antenna configured to receive the radio wave and including a board parallel portion parallel to the circuit board to receive a board horizontally polarized wave having a vibration direction of an electric field parallel to the circuit board; and a case accommodating the circuit board and the horizontally polarized wave antenna, wherein the circuit board is arranged such that the circuit board faces the attachment surface of the vehicle when the vehicle wireless device is attached to the attachment surface, the circuit board has a board region overlapping the board parallel portion without a ground portion being formed in the board region, the ground portion is a conductor plate configured to provide a ground potential for the circuit, a bottom of the case has a facing portion that faces the board parallel portion and at least the facing portion is made of resin, the board parallel portion is arranged such that the board parallel portion is at a distance of λ/4 or more from a vehicle body of the vehicle when the vehicle wireless device is attached to the attachment surface, λ is a wavelength of the radio wave, a side surface of the case has a marker that is a line indicating a position of the board parallel portion provided within the case, the antenna further includes an upright portion standing from the circuit board, and the antenna has a three-dimensional shape in which the board parallel portion is connected to the upright portion at an upper end portion of the upright portion.
9 . A vehicle wireless device configured to be attached to an attachment surface of a vehicle, the device comprising: a circuit board including a dielectric and a circuit configured to transmit or receive a radio wave at a predetermined target frequency of 700 MHz or more; a horizontally polarized wave antenna configured to receive the radio wave and including a board parallel portion parallel to the circuit board to receive a board horizontally polarized wave having a vibration direction of an electric field parallel to the circuit board; a case accommodating the circuit board and the horizontally polarized wave antenna; and a vertically polarized wave antenna configured to receive a board vertically polarized wave having a vibration direction of an electric field perpendicular to the circuit board, wherein the circuit board is arranged such that the circuit board faces the attachment surface of the vehicle when the vehicle wireless device is attached to the attachment surface, the circuit board has a board region overlapping the board parallel portion without a ground portion being formed in the board region, the ground portion is a conductor plate configured to provide a ground potential for the circuit, a bottom of the case has a facing portion that faces the board parallel portion and at least the facing portion is made of resin, the board parallel portion is arranged such that the board parallel portion is at a distance of λ/4 or more from a vehicle body of the vehicle when the vehicle wireless device is attached to the attachment surface, λ is a wavelength of the radio wave, and a side surface of the case has a marker that is a line indicating a position of the board parallel portion provided within the case.
10 . A vehicle wireless device configured to be attached to an attachment surface of a vehicle, the device comprising: a circuit board including a dielectric and a circuit configured to transmit or receive a radio wave at a predetermined target frequency of 700 MHz or more; a horizontally polarized wave antenna configured to receive the radio wave and including a board parallel portion parallel to the circuit board to receive a board horizontally polarized wave having a vibration direction of an electric field parallel to the circuit board; and a case accommodating the circuit board and the horizontally polarized wave antenna, wherein the circuit board is arranged such that the circuit board faces the attachment surface of the vehicle when the vehicle wireless device is attached to the attachment surface, the circuit board has a board region overlapping the board parallel portion without a ground portion being formed in the board region, the ground portion is a conductor plate configured to provide a ground potential for the circuit, a bottom of the case has a facing portion that faces the board parallel portion and at least the facing portion is made of resin, the board parallel portion is arranged such that the board parallel portion is at a distance of λ/4 or more from a vehicle body of the vehicle when the vehicle wireless device is attached to the attachment surface, λ is a wavelength of the radio wave, a side surface of the case has a marker that is a line indicating a position of the board parallel portion provided within the case, the horizontally polarized wave antenna is one of horizontally polarized wave antennas, and the horizontally polarized wave antennas are arranged in a predetermined direction.

Description

CROSS REFERENCE TO RELATED APPLICATIONS The present application is a continuation application of International Patent Application No. PCT/JP2022/023136 filed on Jun. 8, 2022, which designated the U.S. and claims the benefit of priority from Japanese Patent Application No. 2021-103500 filed on Jun. 22, 2021. TECHNICAL FIELD The present disclosure relates to a vehicle wireless device for wireless communication with an external device. BACKGROUND A system performs wireless communication between a mobile device and a vehicle using a radio wave, and determines whether the mobile device is present in a vehicle compartment based on reception statuses of signals from the mobile device in multiple in-vehicle antennas. SUMMARY According to at least one embodiment of the present disclosure, a vehicle wireless device is configured to be attached to an attachment surface of a vehicle. The device includes a circuit board, a horizontally polarized wave antenna and a case accommodating the circuit board and the antenna. BRIEF DESCRIPTION OF DRAWINGS The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. FIG. 1 is an exploded perspective view of a vehicle wireless device. FIG. 2 is a view illustrating an example of an arrangement mode of various components on a circuit board. FIG. 3 is a view illustrating an example of a method for implementing a three-dimensional antenna. FIG. 4 is a view illustrating an example of a formation mode of a ground pattern. FIG. 5 is a schematic view illustrating a radiation direction and a polarization plane of a radio wave radiated from a board parallel portion. FIG. 6 is a diagram illustrating a simulation result of propagation intensity when a dipole antenna is disposed at a position 9 mm away from a C pillar in a posture along a vehicle height direction. FIG. 7 is a diagram illustrating a simulation result of propagation intensity when the dipole antenna is disposed at a position 60 mm away from the C pillar in a posture along the vehicle height direction. FIG. 8 is a view illustrating an effect of an embodiment. FIG. 9 is a view illustrating a modification of a vehicle wireless device. FIG. 10 is a view illustrating a modification of a vehicle wireless device. FIG. 11 is a view illustrating a modification of a vehicle wireless device. FIG. 12 is a view illustrating a modification of a vehicle wireless device. FIG. 13 is a view illustrating a modification of an antenna capable of receiving a board horizontally polarized wave. FIG. 14 is a view illustrating a modification of an antenna capable of receiving a board horizontally polarized wave. FIG. 15 is a view illustrating a modification of an antenna capable of receiving a board horizontally polarized wave. FIG. 16 is a view illustrating a modification of a formation mode of a ground pattern. FIG. 17 is a view illustrating a configuration example of a circuit board when a vehicle wireless device includes a vertically polarized wave antenna. FIG. 18 is a schematic view illustrating a cross section taken along a line XVIII-XVIII illustrated in FIG. 17. FIG. 19 is a view illustrating a modification of a configuration of a circuit board when a vehicle wireless device includes a vertically polarized wave antenna. FIG. 20 is a view illustrating a modification of a configuration of a bottom. FIG. 21 is a view illustrating a configuration example in which multiple antennas are provided. FIG. 22 is a view illustrating another configuration example in which multiple antennas are provided. DETAILED DESCRIPTION To begin with, examples of relevant techniques will be described. A vehicle wireless device is a device for wireless communication with an external device, such as a mobile terminal carried by a user or other vehicles. According to a comparative example, a system performs wireless communication between a mobile device and a vehicle using a radio wave of 2.45 GHz or the like, and determines whether the mobile device is present in a vehicle compartment based on reception statuses of signals from the mobile device in multiple in-vehicle antennas. A reception state (for example, a reception strength) of a signal from a mobile terminal carried by a user can be used for detecting approach of the user to the vehicle or estimating a position of the user relative to the vehicle. In view of such usages, when the user is in the vicinity of the vehicle, it may be preferable that the vehicle wireless device can satisfactorily communicate with the mobile terminal regardless of a position and direction of the user relative to the vehicle. However, a high-frequency radio wave of 700 MHz or more, such as a radio wave in 2.4 GHz band, travels straighter than a radio wave of 300 kHz or less in a low-frequency (LF) band, and the high-frequency radio wave is less likely to wrap around a metal portion of a vehic