Structure for mounting cameras on a vehicle

Abstract: Each of the CCD cameras (10A, 10B) for making a film of a vehicle forward road environment is mounted on the both ends of a chassis (16) with a high stiffness. A mounting seat member (17) is formed at a center of the chassis (16). The CCD cameras (10A, 10B) are mounted onto a vehicle body through fixing the mounting seat member (17) onto the vehicle body. Portions other than the mounting seat member (17) of the chassis (16) are disposed apart from the vehicle body.

Description: BACKGROUND OF THE INVENTION The present invention relates to a structure for mounting cameras on a vehicle as described in the preamble of claim 1. In recent years, a vehicle drive supporting system with a camera mounted on a vehicle has been proposed, wherein information for safety is supplied to a driver, or a vehicle control is automatically performed, based on the forward data in a vehicle running direction which are obtained by the camera while running. Conventionally, as a mounting structure of a camera mounted on a vehicle, a structure described in a publication of Japanese Patent Application Laid-Open No. 11-78717 has been known. The publication discloses a structure for mounting a camera inside a front windshield (front glass) of a vehicle, or for mounting a camera as a unit on a room mirror for confirming a rearward direction. When the mounting structure described in the above-mentioned publication is applied to so-called stereo cameras which have one camera on the right and left sides, respectively, two cameras are mounted on each side of a front glass through a stay. However, in this mounting method, there are problems that each position of the both cameras is apt to be relatively tilted because of unavoidable unevenness when manufacturing the front glass and a vehicle body. If each position of cameras is deviated from a correct position thereof, an accuracy of obtained image data may be lowered. As a result, for example, the distance measurement between a car and a forward running car might not be berformed accurately, so that the vehicle drive supporting system can not be accurately operated. Furthermore, since the cameras are independently fixed on the front glass through the stay according to the conventional method, a relative accuracy of an optical axis between the cameras mounted on both sides is apt to change because of vibration caused while running, a distortion of vehicle body, and a temperature difference inside a vehicle, so that the accuracy of obtained image data is lowered. In addition, a posture such as angle must be adjusted in each camera upon manufacturing, wherein it takes much time to do so. As a result, a productive efficiency thereof is lowered. Reference is also made to EP-A-476 748, US-A-4 669 843 and JP-A-60119192. EP-A- 476 748, which comprises the features mentioned in the preamble of claim 1, discloses a multi-section helicopter-borne rotatable beam for supporting at either of its ends range-finder cameras and television focusing cameras for sterophotogrammetric surveys. A central tubular section is rotated by means of an electric motor and return springs and supported by two collars mounted rotatably by means of hinged constraints on a base fixed rigidly to the floor of the helicopter cab. Two truncated-cone tubular-structure side sections of the beam are secured to the said central section by a telescopic coupling arrangement ensured by half-ring ties co-operating with flanges of the said sections and by through pins and safety split pins, the cameras being supported by a prismatic box frames supported by means of a dampening system. US-A-4 669 843 discloses a helibome beam for supporting at its two ends metric photocameras suitable for industrial sterophotogrammetric surveys. A plurality of cylindrical tubular sections are linked in sequence with each other by means of flanges, and are manually rotatable, but not longitudinally sliding, with their center section inserted inside three clamp collars mounted, through double-effect cylindrical shock absorbers, on a base or bench fastened on to the floor of helicopter's cabin. At the end of the beam, two cylindrical housings with aerodynamic closure elements and provided with an "eyelid" door, inside which the photocameras are supported by means of a frame linked to the housing by means of two respectively radial and axial shock absorbing units, and provided with two inner guides into which the side supporting pins of the said photocamera are inserted. In JP-A- 60119192 the positions of two television cameras are adjusted easily and the cameras are made to correspond to a dynamic object by turning a supporting means while always catching the object by any one of the first and second television cameras, and catching both the focal distances of the first and second cameras and the object. The television cameras are supported by the supporting member so that angular adjustment is attained in accordance with the horizontal and vertical directions respectively and can catch the object. Once the user catches the object through the camera by operating an operation board, the supporting member is turned around a shaft while catching the object through the camera to form the correlation between the video signals of both the cameras. SUMMARY OF THE INVENTION The present invention has been developed in view of the aforementioned problems, and an object of the present invention is to provide a structure for mounting cameras on a vehicle wherein a relative position between cameras disposed on the both sides can be accurately kept even if vibration while running and/or a temperature difference inside a vehicle influences the cameras, so that an accuracy of the obtained image data is not lowered under any situation. In a first aspect of the present invention there is provided a structure for mounting cameras on a vehicle as described in claim 1. According to the above-mentioned constructions, since the two cameras are mounted on the both ends of the chassis, the relative accuracy of each optical axis between the right and left cameras can be prevented from lowering due to vibration when running or temperature difference. Also, since the chassis is fixed onto the vehicle body with a small compressed area, the image data obtained from the both cameras suffers little influence of vibration when running, and the like, so that the reliability of a drive supporting system can be improved. In one embodiment, said wedge-like taper plate is selected from a group consisting of taper plates having different taper angles so that said optical axis of said stereo cameras is directed into a correct direction when said chassis is mounted onto the mounting position of the vehicle body. In one embodiment, said chassis has a cross section consisting of a plate-like main body extending in said lateral direction and a hook-like curved portion integrally formed along a front edge of said main body. In one embodiment, said chassis is formed from one material having a high coefficient of thermal conductivity for performing the thermal conductivity quickly so as to keep a thermal balance between said pair of cameras. In one embodiment, said chassis is formed from an aluminum alloy. In one embodiment, said chassis is mounted onto a front rail of said vehicle body. In one embodiment, said mounting support seat member supports all the weight of the chassis including said cameras after said chassis is fixed to the vehicle body. In one embodiment, the structure further comprises a circuit cover for covering an underside face of the chassis, and a circuit substrate for controlling each of the cameras, wherein said circuit substrate is contained in a space between the chassis and the circuit cover. In one embodiment, said mounting seat member is provided with pins onto its upper face, said pins engaging positioning holes of the vehicle body so as to position the chassis at the predetermined mounting position of the vehicle body. In one embodiment, said mounting seat member has a width of about 50 mm in the lateral direction. In one embodiment, the structure further comprises a falling prevention means for preventing said chassis from falling when said chassis is mounted onto said vehicle body. The falling prevention means may comprise a pair of brackets attached on an upper portion of both ends of said chassis, having at least one split pin inserted into said vehicle body before said chassis is mounted onto the vehicle body; and a pair of belts being connected to said bracket at one end thereof and to said chassis at another end thereof. In one embodiment, said belts are bent in a U-shape and do not support said chassis when said chassis is mounted onto the vehicle body. BRIEF DESCRIPTION OF THE DRAWINGS By way of example only, a specific embodiment of the present invention will now be described, with reference to the accompanying drawings, in which:- Fig. 1 is an explanatory view showing a vehicle drive supporting system having a mounting structure of cameras on a vehicle according to the present invention; Fig. 2 is a front view of a chassis which is an important portion of the mounting structure of cameras on a vehicle according to the present invention; Fig. 3 is a sectional view along A-A line of Fig. 2; Fig. 4 is a bottom view of the chassis according to the present invention; Fig. 5 is a side view of the chassis according to the present invention; and Fig. 6 is an exploded perspective view of the mounting structure of cameras on a vehicle according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a mounting structure of cameras on a vehicle to which the present invention is applied will be explained below with reference to the attached drawings. FIG. 1 is an explanatory view of a vehicle drive supporting system using cameras mounted on a vehicle. Figs. 2-6 are views showing a mounting structure of cameras on a vehicle according to the present invention. First, a summary of the vehicle drive supporting system will be explained hereinafter. The drive supporting system has a pair of charge coupled device cameras (hereinafter called CCD cameras) 10A, 10B for recognizing a forward road environment while running. An image signal obtained by these CCD cameras 10A, 10B in the vehicle running direction is inputted into an image processing unit 12, wherein the image signal is converted to various kinds of forward data such as distance data. Furthermore, the obtained forward data, a road data outputted from a navigation system (not shown), and data of a vehicle running condition are inputted into a preview control unit (hereinafter call PCU) 14. The PCU 14 raises an alarm with regard to a distance between the car and a forward running car, and carries out various kinds of control for a drive supporting such as cruise control. Therefore, the high accuracy of the forward data obtained by the CCD cameras 10A, 10B is indispensable for accurately operating the drive supporting system. The object of the present invention is to obtain an exact forward data through improving a mounting structure of the CCD cameras 10A, 10B on a vehicle and thereby raising a relative mounting accuracy between the CCD cameras 10A, 10B. As shown in Fig. 1, the mounting structure of cameras of the present invention includes a chassis 16 for mounting the two CCD cameras 10A, 10B inside a vehicle as an important parts. The chassis 16 is a member which extends in a lateral direction. The CCD cameras 10A, 10B are mounted one on each end of the chassis 16 which is formed by only one material having a high-stiffness and a high-coefficient of thermal conductivity such as an aluminum alloy. On the central portion of the chassis 16 is integrally formed a mounting seat member 17 for fixing the chassis 16 on a front rail 40 of a vehicle body, which partially extends to the rear of the chassis 16. Two pins 18 are attached onto an upper face of the mounting seat member 17. The pins 18 are engaged with positioning holes of the front rail 40 so as to position the chassis 16 at a predetermined mounting portion. As shown in Figs. 1 and 2, the mounting seat member 17 includes three fixing holes 21 where bolts 42 for fixing the chassis 16 are inserted, as well as the pins 18. The mounting seat member 17 is formed with a width of, for example, only about 50mm, and thus an area for mounting the mounting seat member 17 on the front rail 40 is very small. When the chassis 16 is fixed on the front rail 40, a wedge-like taper plate 20 intervenes between the mounting seat member 17 and the front rail 40 as shown in Figs. 2 and 3. A plurality of taper plates 20 with different taper angles are prepared in advance so as to enable a vertical angle of an optical axis of the CCD cameras 10A, 10B to change. As examples of the taper plate 20, there is a taper plate, a front side or a rear side of which is thinly formed, or which is evenly flat. When fixing the chassis 16, the taper plate 20 with a most adequate taper angle is selected, so that the optical axis of the CCD cameras 10A, 10B mounted on the chassis 16 can be minutely adjusted so as to be directed into the predetermined correct direction. As shown in Fig. 1, on a back face of the chassis 16 are mounted connectors 2 2A, 22B for outputting image data obtained by the right and left CCD cameras 10A, 10B. Also, as shown in Figs. 3 and 4, an underside face of the chassis 16 is covered by a circuit cover 24, in which a circuit substrate 26 for controlling each of the CCD cameras 10A,10B is contained in a space between the chassis 16 and the circuit cover 24 . The chassis 16 has a hooked sectional shape extending in a lateral direction to prevent the chassis 16 from being transformed due to a weight of the CCD cameras 10A, 10B and/or an acceleration while running. The CCD cameras 10A, 10B and the chassis 16 fixed inside a vehicle are covered by an outside cover 27 made of resin, which has engaging portions 28A to be engaged with the chassis 16 at a tip end thereof, and recess portions 28 with a hole where bolts 30 are inserted. The outside cover 27 is mounted at a predetermined portion of the front rail 40 through fastening the bolts 30 into the front rail 40. The recess portion 28 is covered by a cap 32 after fastening the bolts 30. The chassis 16 is supported on the front rail 40 inside a vehicle by the mounting seat member 17. As shown in Fig. 2, falling prevention brackets 34 are attached on an upper portion of both ends of chassis 16, and split pins 36 on an upper end thereof are inserted into holes (not shown) of the front rail 40. As shown in Fig. 5, the falling prevention bracket 34 is formed so as to cover the both upper ends of the chassis 16 as shown from right to left in Fig. 5. A front portion 34A of the bracket 34 is connected to a front end portion 16A of the chassis 16 through a belt 38 with U-shape shown in the side view in a vehicle running direction. Whereas the belt 38 prevents the chassis 16 from falling when mounting it, the mounting seat member 17 supports all weight of the chassis 16 including the CCD cameras 10A, 10B after the chassis 16 is fixed to the vehicle through using the taper plate 20. That is, the portions other than the mounting seat member 17 of the chassis 16 are kept under the conditions disposed substantially apart from the vehicle body after being fixed. As mentioned above and shown in Fig. 6, according to the mounting structure of cameras on a vehicle of the present invention, the CCD cameras 10A, 10B are mounted on the both ends of the chassis 16, and the mounting seat member 17 disposed in the center of the chassis 16 is attached with fixing holes (not shown) of the front rail 40 by screwing the three bolts 42, so that the chassis 16 can be fixed onto the front rail 40 with a small compressed area. Thus, the CCD cameras 10A, 10B suffer little influence of vibration when running and of change of temperature inside a vehicle, so that the accuracy of mounting the both cameras 10A, 10B, i. e. of an optical axis thereof can be maintained. Consequently, the image data of the front environment obtained by the CCD cameras 10A, 10B can be prevented from deteriorating, and the reliability of the driving support system can be improved. In addition, according to the present invention, the most adequate one of a plurality of taper plates 20 is selected and intervenient between the mounting seat member 17 and the front rail 40, so that an angle adjustment of the CCD cameras 10A, 10B can be easily made. Furthermore, the chassis 16 supporting the CCD cameras 10A, 10B has enough cross-sectional area, and is formed by a uniform material with high-stiffness and high-coefficient of thermal conductivity. Therefore, a dimensional accuracy between the CCD cameras 10A, 10B is improved, and the thermal conductivity through the chassis 16 is performed quickly, so that there occurs little temperature difference between the CCD cameras 10A, 10B even if daylight is given on only one side, namely a thermal balance between the both cameras can be kept. As a result, an image output characteristic of the right and left CCD cameras is uniform, and the obtained image data is stabilized.

Claims: A structure for mounting cameras on a vehicle, comprising: a chassis (16) having a predetermined length and extending in a lateral direction of the vehicle body; and a mounting seat member (17) formed in the center of an upper face of said chassis (16) for mounting said chassis onto a predetermined mounting position of said vehicle body; a pair of cameras (10A, 10B) mounted on said chassis (16) for obtaining an image signal of a forward road environment, each camera being mounted on a respective end of said chassis; and a plate (20) sandwiched by said mounting seat member (17) of said chassis (16) and said mounting position of said vehicle body when said chassis is mounted onto said vehicle body; wherein portions other than said mounting seat member (17) of the chassis (16) are disposed apart from the vehicle body; characterized in that said plate is formed as a wedge-like plate (20) for adjusting a vertical angle of the optical axis of said cameras (10A, 10B). A structure for mounting cameras on a vehicle according to claim 1, wherein: said wedge-like taper plate (20) is selected from a group consisting of taper plates having different taper angles so that said optical axis of said cameras (10A, 10B) is directed into a correct direction when said chassis (16) is mounted onto the mounting position of the vehicle body. A structure for mounting cameras on a vehicle according to claim 1 or claim 2, wherein: said chassis (16) has a cross section consisting of a plate-like main body extending in said lateral direction and a hook-like curved portion integrally formed along a front edge of said main body. A structure for mounting cameras on a vehicle according to any of claims 1 to 3, wherein said chassis is formed from one material having a high coefficient of thermal conductivity for performing the thermal conductivity quickly so as to keep a thermal balance between said pair of cameras (10A, 10B). A structure for mounting cameras on a vehicle according to claim 4, wherein: said chassis (16) is formed from an aluminum alloy. A structure for mounting cameras on a vehicle according to any of claims 1 to 5, wherein: said chassis (16) is mounted onto a front rail (40) of said vehicle body. A structure for mounting cameras on a vehicle according to any of claims 1 to 6, wherein: said mounting support seat member (17) supports all the weight of the chassis (16) including said cameras (10A, 10B) after said chassis (16) is fixed to the vehicle body. A structure for mounting cameras on a vehicle according to any of claims 1 to 7, further comprising: a circuit cover (24) for covering an underside face of the chassis (16), and a circuit substrate (26) for controlling each of the cameras (10A, 10B), wherein said circuit substrate (26) is contained in a space between the chassis (16) and the circuit cover (24). A structure for mounting cameras on a vehicle according to any of claims 1 to 8, wherein: said mounting seat member (17) is provided with pins (18) onto its upper face, said pins (18) engaging positioning holes of the vehicle body so as to position the chassis (16) at the predetermined mounting position of the vehicle body. A structure for mounting cameras on a vehicle according to any of claims 1 to 9, wherein said mounting seat member (17) has a width of about 50 mm in the lateral direction. A structure for mounting cameras on a vehicle according to any of claims 1 to 10, further comprising a falling prevention means (34, 36, 38) for preventing said chassis from falling when said chassis (16) is mounted onto said vehicle body. A structure for mounting cameras on a vehicle according to claim 11, wherein said falling prevention means comprises: a pair of brackets (34) attached on an upper portion of both ends of said chassis (16), having at least one split pin (36) inserted into said vehicle body before said chassis is mounted onto the vehicle body; and a pair of belts (38) being connected to said bracket (34) at one end thereof and to said chassis at another end thereof. A structure for mounting cameras on a vehicle according to claim 12, wherein said belts (38) are bent in a U-shape and do not support said chassis (16) when said chassis is mounted onto the vehicle body.

Inventors: TOZAWA YOSHIO, TOZAWA, YOSHIO, Tozawa, Yoshio, c/o Fuji Jukogyo K.K.
Applicants: FUJI HEAVY IND LTD, FUJI JUKOGYO KABUSHIKI KAISHA
Application year: 2000
Main classification: B60R11
IPC codes: B60R1, B60R11, G01C11