U.S. patent application number 09/785256 was filed with the patent office on 2002-03-28 for vehicle surroundings monitoring device.
Invention is credited to Matsuoka, Katsuji.
Application Number | 20020038170 09/785256 |
Document ID | / |
Family ID | 18778729 |
Filed Date | 2002-03-28 |
United States Patent
Application |
20020038170 |
Kind Code |
A1 |
Matsuoka, Katsuji |
March 28, 2002 |
Vehicle surroundings monitoring device
Abstract
A vehicle surroundings monitoring device in which reflection by
a mirror is reduced to ensure the desired performance of distance
measurement even in a short-distance range. The monitoring device
for monitoring surroundings around a vehicle has a transmitting
antenna provided in a door mirror assembly of the vehicle to
radiate transmitted waves through a mirror surface of the door
mirror, and a receiving antenna provided in the door mirror
assembly to receive, through the door mirror surface, reflected
waves from an object existing near the vehicle. In the this
monitoring device, electric wave transmission surfaces are formed
as portions of the door mirror surface corresponding to openings
surfaces for the transmitting and receiving antennas to limit
reflection by the door mirror surface and to enable transmission of
electric waves through the door mirror surface. The electric wave
transmission surfaces are formed by partially removing a reflective
film formed on the mirror surface, by partially cutting off the
mirror surface, or by forming metal slits in portions of the door
mirror surface or through the entire door mirror surface.
Inventors: |
Matsuoka, Katsuji; (Tokyo,
JP) |
Correspondence
Address: |
SUGHRUE, MION, ZINN, MACPEAK & SEAS
2100 Pennsylvania Avenue, N.W.
Washington
DC
20037
US
|
Family ID: |
18778729 |
Appl. No.: |
09/785256 |
Filed: |
February 20, 2001 |
Current U.S.
Class: |
701/34.4 ;
701/49 |
Current CPC
Class: |
G01S 7/032 20130101;
G01S 7/025 20130101; H01Q 1/3233 20130101; H01Q 1/3266 20130101;
G01S 13/931 20130101 |
Class at
Publication: |
701/29 ;
701/49 |
International
Class: |
G01S 007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 28, 2000 |
JP |
2000-296453 |
Claims
What is claimed is:
1. A vehicle surroundings monitoring device which monitors
surroundings around a vehicle, said device comprising: a
transmitting antenna mounted in a door mirror assembly of the
vehicle, said transmitting antenna for radiating transmitted waves
through a mirror surface of a door mirror in the door mirror
assembly; a receiving antenna mounted in the door mirror assembly,
said receiving antenna for receiving, through the mirror surface of
the door mirror, reflected waves from an object existing in the
surroundings of the vehicle; and electric wave transmission
surfaces formed as portions of the door mirror surface
corresponding to opening surfaces for said transmitting and
receiving antennas to limit reflection by the door mirror surface
and to enable transmission of electric waves through the door
mirror surface.
2. A vehicle surroundings monitoring device according to claim 1,
wherein said electric wave transmission surfaces in the door mirror
surface are formed by partially removing a reflective film formed
on the mirror surface.
3. A vehicle surroundings monitoring device according to claim 1,
wherein said electric wave transmission surfaces in the door mirror
surface are formed by partially cutting off the mirror surface.
4. A vehicle surroundings monitoring device according to claim 1,
wherein said electric wave transmission surfaces in the door mirror
surface are formed by forming metal slits in portions of the door
mirror surface or through the entire door mirror surface.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a vehicle surroundings
monitoring device mounted on a vehicle and used for monitoring of
surroundings around the vehicle and, more particularly, to a
vehicle surroundings monitoring device for alarming a driver to
enable the driver to avoid contact with or collision against an
obstacle particularly at the time of lane change or the like.
[0003] The entire content of the basic Japanese Patent Application
from which the priority under the Convention is claimed in this
application is hereby incorporated by reference into this
application.
[0004] 2. Description of the Related Art
[0005] Various radar devices have been proposed which are widely
used as a vehicle surroundings monitoring device, a controller for
controlling the distance of a vehicle from another vehicle, etc.,
by being mounted on vehicles.
[0006] For example, Japanese Patent Application Laid-Open No. Sho
54-45040 discloses a vehicle surroundings monitoring device having
a radar unit. This device is formed by using a portion of a fender
mirror and a fender portion of a vehicle.
[0007] In the above-described conventional device, a mirror surface
is used as an antenna reflector, and electric waves are externally
radiated to the mirror surface by using a feeder horn antenna. The
feeder horn is therefore exposed to the outside and there is a
possibility breakage of the feeder horn or failure of maintenance
of the desired performance due to external causes.
[0008] Therefore, it is desirable that such an antenna should be
housed in a body of a mirror assembly. However, if an antenna is
incorporated in a mirror assembly, electric waves from the antenna
are reflected by the mirror to cause the radar to operate as if an
obstacle always exists within a short distance from the vehicle.
When an object actually exists within a short distance from the
vehicle, the radar cannot detect the object if the distance
resolution of the radar is not sufficiently high. Also, the
distance measuring performance may be influenced by the reflection
by the mirror to such an extent that the possibility of detection
failure or a false alarm is high.
SUMMARY OF THE INVENTION
[0009] In view of the above-described problem, an object of the
present invention is to provide a vehicle surroundings monitoring
device in which reflection by a mirror is reduced to ensure the
desired performance of distance measurement even in a
short-distance range.
[0010] To achieve the above-described objects, according to one
aspect of the present invention, there is provided a vehicle
surroundings monitoring device which monitors surroundings around a
vehicle, the device is characterized by comprising a transmitting
antenna mounted in a door mirror assembly of the vehicle, said
transmitting antenna for radiating transmitted waves through a
mirror surface of a door mirror in the door mirror assembly, a
receiving antenna mounted in the door mirror assembly, the
receiving antenna for receiving, through the mirror surface of the
door mirror, reflected waves from an object existing in the
surroundings of the vehicle, and electric wave transmission
surfaces formed as portions of the door mirror surface
corresponding to opening surfaces for said transmitting and
receiving antennas to limit reflection by the door mirror surface
and to enable transmission of electric waves through the door
mirror surface.
[0011] Also, the electric wave transmission surfaces in the door
mirror surface are formed by partially removing a reflective film
formed on the mirror surface.
[0012] Also, the electric wave transmission surfaces in the door
mirror surface are formed by partially cutting off the mirror
surface.
[0013] Also, the electric wave transmission surfaces in the door
mirror surface are formed by forming metal slits in portions of the
door mirror surface or through the entire door mirror surface.
[0014] In the vehicle surroundings monitoring device of the present
invention, electric wave transmission surfaces for limiting
reflection and for enabling transmission of electric waves are
formed as portions of the door mirror surface corresponding to
opening surfaces for the transmitting and receiving antennas,
thereby limiting reflection by the door mirror surface and
maintaining the desired short-range distance measuring performance
to provide unerring alarm information to a driver.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In the accompanying drawings:
[0016] FIG. 1 is a block diagram showing the configuration of a
vehicle surroundings monitoring device in Embodiment 1 of the
present invention;
[0017] FIG. 2 is a diagram showing a door mirror surface in
Embodiment 1 of the present invention;
[0018] FIG. 3 is a cross sectional view of the door mirror surface
in Embodiment 1 of the present invention;
[0019] FIG. 4 is a diagram showing a door mirror surface in
Embodiment 2 of the present invention;
[0020] FIG. 5 is a cross sectional view of the door mirror surface
in Embodiment 2 of the present invention;
[0021] FIG. 6 is a diagram showing a door mirror surface in
Embodiment 3 of the present invention;
[0022] FIG. 7 is a cross sectional view of the door mirror surface
in Embodiment 3 of the present invention; and
[0023] FIG. 8 is a diagram for explaining a content of Embodiment 3
of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] The present invention will be described with respect to
embodiments thereof in which embodiments of the present invention
in which electric wave transmission surfaces for limiting
reflection and for enabling transmission of electric waves are
formed as portions of the door mirror surface corresponding to
opening surfaces for the transmitting and receiving antennas.
Embodiment 1
[0025] A vehicle surroundings monitoring device which represents
Embodiment 1 of the present invention will be described with
reference to FIG. 1.
[0026] Referring to FIG. 1, a vehicle surrounding monitoring device
mounted on a vehicle includes a radar 1 and a display 6. The radar
1 has a transmitting antenna 2 for radiating transmitted waves
through a door mirror surface described below; a receiving antenna
3 for receiving, through the door mirror surface, reflected waves
from an object existing near the vehicle; a high-frequency circuit
unit 4 having a transmitting circuit for sending out transmitted
waves and a receiving circuit supplied with received waves; and a
signal processing circuit unit 5. Results of signal processing in
the signal processing circuit 5 are displayed on the display 6 to
provide information to a driver.
[0027] The radar 1 is mounted in a door mirror assembly of the
vehicle, and the display 6 may be placed inside the vehicle or in
the vicinity of the door mirror assembly.
[0028] FIG. 2 is a diagram showing the door mirror surface, and
FIG. 3 is a cross sectional view of the door mirror surface.
[0029] In FIGS. 2 and 3, the door mirror surface is indicated by 7,
opening surfaces for the transmitting antenna 2 and the receiving
antenna 3 are indicated by 8, a mirror base is indicated by 9, and
a reflective film is indicated by 10. As shown in the cross
sectional view of FIG. 3, the door mirror surface 7 is formed by
the reflective film 10 on the mirror base 9, but the door mirror
surface 7 has such a structure that the reflective film 10 is
removed from the portions of the door mirror surface 7
corresponding to the opening surfaces 8, thereby forming electric
wave transmission surfaces for limiting reflection caused by the
mirror surface while enabling transmission of electric waves.
[0030] The operation of this embodiment will now be described.
[0031] Electric waves generated by the high-frequency circuit 4 are
radiated out of the vehicle from the transmitting antenna 2 through
the door mirror surface 7 and are reflected by an obstacle such as
another vehicle existing near the vehicle having the monitoring
device. The reflected waves enter the door mirror through the door
mirror surface 7 to be received by the receiving antenna 3 and
input to the high-frequency circuit unit 4. The received waves
input to the high-frequency circuit unit 4 are down-converted into
a low-frequency signal. This signal is input to the signal
processing circuit 5, in which the distance to the obstacle, etc.,
are computed. If a risk of collision against the obstacle is
thereby recognized, the driver is alerted to the risk by the
display 6.
[0032] The amount of electric waves reflected by the door mirror
surface 7 is extremely small because of the above-described
structure in which the reflective film 10 is removed from the
mirror portions corresponding to the opening surfaces 8 for the
transmitting antenna 2 and the receiving antenna 3. Therefore, the
great part of the electric waves are radiated to the external
space. Also, reflected waves from an obstacle can be received by
the receiving antenna 3 without being reflected by the door mirror
surface 7.
[0033] In the case of a radar, the distance resolution (ability to
separately recognize two objects) is determined from the bandwidth,
and the performance of distance measurement in a short-distance
range is low when reflected waves are detected through an extremely
small distance. However, by reducing the influence of reflection by
the door mirror surface 7 as in Embodiment 1, the desired
short-range distance measuring performance can be maintained and
therefore the occurrence of a false alarm can be reduced.
Embodiment 2
[0034] Embodiment 2 of the present invention also has the
configuration shown in the block diagram of FIG. 1, as in
Embodiment 1. only features of Embodiment 2 not described with
respect to Embodiment 1 will be described below.
[0035] FIG. 4 is a diagram showing a door mirror surface, and FIG.
5 is a cross sectional view of the door mirror surface.
[0036] In FIGS. 4 and 5, components corresponding to those of
Embodiment 1 shown in FIGS. 2 and 3 are indicated by the same
reference numerals. The description for the corresponding
components will be omitted.
[0037] In Embodiment 2, the structure of the mirror is such that,
as shown in FIG. 5 in detail, portions corresponding to opening
surfaces 8 for the transmitting and receiving antennas, of the
mirror base 9 and the reflective film 10 forming a portion of the
door mirror surface 7, are cut and removed to form electric wave
transmission surfaces for limiting reflection by the mirror surface
and for enabling transmission of electric waves.
[0038] The amount of electric waves reflected by the door mirror
surface is extremely small because of the above-described structure
in which the portions of the mirror surface corresponding to the
opening surfaces 8 for the transmitting antenna 2 and the receiving
antenna 3 are cut off. Therefore, a great part of the electric
waves are radiated to the external space. Also, reflected waves
from an obstacle can be received by the receiving antenna 3 without
being reflected by the door mirror surface 7. As a result, the
desired short-range distance measuring performance can be
maintained and the occurrence of a false alarm can therefore be
reduced.
Embodiment 3
[0039] Embodiment 3 of the present invention also has the
configuration shown in the block diagram of FIG. 1, as in
Embodiment 1. Only features of Embodiment 3 not described with
respect to Embodiment 1 will be described below.
[0040] FIG. 6 is a diagram showing a door mirror surface.
[0041] In FIG. 6, components corresponding to those of Embodiment 1
shown in FIG. 2 are indicated by the same reference numerals. The
description for the corresponding components will be omitted.
[0042] In Embodiment 3, the structure of the mirror is such that,
as shown in FIG. 6, metal slits are formed in portions of the
mirror surface corresponding to opening surfaces 8 of the
transmitting and receiving antennas, thereby forming electric wave
transmission surfaces for limiting reflection by the mirror surface
and for enabling transmission of electric waves.
[0043] In general, when linearly polarized electric waves are
incident upon metal slits, the electric waves can pass the slits
under such a condition that, as shown in FIG. 8, metal slits 11 are
arranged in the direction perpendicular to polarized waves (see
electric field plane 12) ("Radar Gijutu" The Institute of
Electronics, Information and Communication Engineers, p113).
[0044] Also, metal slits may be formed through the entire door
mirror surface 7 to form an electric wave transmission surface.
[0045] The amount of electric waves reflected by the door mirror
surface is extremely small because of the above-described structure
in which metal slits are formed in the portions of the mirror
surface corresponding to the opening surfaces 8 for the
transmitting antenna 2 and the receiving antenna 3, or metal slits
are formed through the entire mirror surface. Therefore, a great
part of the electric waves are radiated to the external space.
Also, reflected waves from an obstacle can be received by the
receiving antenna 3 without being reflected by the door mirror
surface 7. As a result, the desired short-range distance measuring
performance can be maintained and the occurrence of a false alarm
can therefore be reduced. While the metal slits extending in the
vertical direction in the door mirror surface have been described,
metal slits extending in the horizontal direction may be formed by
considering polarization of electric waves.
[0046] According to the present invention, as described above,
electric wave transmission surfaces for limiting reflection and for
enabling transmission of electric waves are formed as portions of
the door mirror surface corresponding to opening surfaces for the
transmitting and receiving antennas, thereby limiting reflection by
the door mirror surface and maintaining the desired short-range
distance measuring performance to provide unerring alarm
information to a driver.
[0047] Also, the electric wave transmission surfaces in the door
mirror surfaces can be formed by partially removing the reflective
film on the mirror surface, by partially cutting off the mirror
surface, or by forming metal slits in portions of the door mirror
surface or through the entire door mirror surface, thus making it
possible to limit reflection by the door mirror surface, to
maintain the desired short-range distance measuring performance,
and to provide unerring alarm information to a driver.
* * * * *