Vehicle-mounted camera system

The present invention relates to vehicle-mounted camera systems mounted on vehicles for imaging the surroundings of the vehicles.

For camera systems in which a camera images a dead angle in the surroundings of a vehicle and the picked up image is displayed on a display screen inside the car, methods of displaying a picked up image with various screen designs are being studied so that a driver can instinctively understand a sense of direction and a sense of distance on the picked up image displayed on the display screen.

In one of those screen designs, a mask image is superimposed on part of a picked up image so that that part of the picked up image is not displayed on a display screen. When an imaging element inside a camera receives high-luminance light such as the sun or a headlight of an oncoming vehicle, this type of screen design can prevent the light reflected on a picked up image from being displayed on a display screen by the mask image.

Typically, when an imaging element receives high-luminance light, an image of the light is reflected and a smear occurs due to that light on its picked up image. The mask image only hides the image of the light and cannot hide the smear due to the light in the screen design mentioned above. Thus when an area corresponding to the mask image in the imaging element receives high-luminance light, the display screen displays a strange image where the image of the high-luminance light is not reflected but only the smear has occurred.

The above camera systems have another disadvantage of reflecting a ghost or stray light on a picked up image when the imaging element receives external light from outside the angle of view.

Therefore, the present invention has an object to provide a vehicle-mounted camera system capable of preventing the occurrence of only a smear in an area without a mask image on a picked up image, and substantially reducing a ghost and stray light.

To solve the aforementioned problems, in a first aspect of a vehicle-mounted camera system according to the present invention, the system comprises: an imaging element; an imaging lens disposed in front of the imaging element; a displaying means including a display screen displaying a picked up image picked up by the imaging element; a superimposing means for superimposing the picked up image and a mask image displayed on part of the display screen; and a light-shielding member shielding part of light which enters the imaging lens, wherein the light-shielding member is arranged to appear in an area displaying the mask image on the display screen.

In a second aspect of the vehicle-mounted camera system according to the present invention, particularly in the first aspect, the mask image is superimposed on an upper area of the picked up image, and the light-shielding member is arranged in an upper area of the angle of view of the imaging lens.

According to the first aspect of the vehicle-mounted camera system of the present invention, because the light-shielding member is arranged to appear in an area displaying the mask image on the display screen, (1) the light-shielding member can be secured as large as possible while keeping the member from appearing on the picked up image, (2) high-luminance light which enters the range corresponding to the mask image within the angle of view can be shielded so as not to be received by the imaging element, thus preventing the occurrence of only a smear in an area without the mask image on the picked up image, and (3) the light-shielding member, which is arranged within the angle of view of the imaging lens, can be formed over a large area, to substantially shield incident light from outside the angle of view, thus substantially reducing a ghost and stray light.

According to the second aspect of the vehicle-mounted camera system of the present invention, because the mask image is superimposed on the upper area of the picked up image, and the light-shielding member is arranged in the upper area of the angle of view of the imaging lens, external light (high-luminance incident light, or incident light that causes a ghost and stray light) which enters the upper area of the angle of view of the imaging lens can be shielded appropriately.

These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

FIG. 1 is a general view of the structure of a vehicle-mounted camera system according to a preferred embodiment of the present invention.

FIG. 2 is a disassembled perspective view of a camera.

FIG. 3 illustrates an example of a picked up image on which a mask image is superimposed.

FIG. 4 is a cross-sectional view of FIG. 2 taken along the line IV-IV (side cross-sectional view of a lens cover).

FIG. 5 is a front view of the lens cover.

FIG. 6 is a side view of the lens cover.

FIG. 7 is a bottom view of the lens cover.

FIG. 8 is a top view of the lens cover.

FIG. 1 is a general view of the structure of a vehicle-mounted camera system according to a preferred embodiment of the present invention.

As shown in FIG. 1 , this vehicle-mounted camera system 1 includes a camera (imaging means) 3 mounted on a vehicle for imaging the surroundings of the vehicle, a superimposition circuit (superimposing means) 5 for superimposing a mask image Gm on part (e.g. an upper area G 1 of a picked up image G shown in FIG. 3 ) of the picked up image G of the camera 3 , and a display device 7 installed on the vehicle for displaying the picked up image G processed by the superimposition circuit 5 .

The camera 3 includes a camera body 30 and a lens cover 31 mounted on the camera body 30 , as shown in FIG. 2 .

The camera body 30 includes a circuit substrate 30 b having an imaging element 30 a mounted thereon, an imaging lens 30 c disposed in front of the imaging element 30 a , a front case 30 d housing the circuit substrate 30 b while holding the imaging lens 30 c , and a rear case 30 e . The front case 30 d includes a cylindrical holder part 30 g at the front of a box-shaped case part 30 f with an open rear surface, for example, the holder part 30 g being provided to communicate with the inside of the case part 30 f . The case part 30 f houses the circuit substrate 30 b fixed therein by screws 30 h , for example, and the holder part 30 g holds the imaging lens 30 c . In addition, engagement protrusions 30 i are formed on side surfaces (upper side surface and lower side surface in this case) of the case part 30 f of the front case 30 d . The rear case 30 e includes a flange part 30 k provided on the periphery of the front of a box-shaped case part 30 j with an open front surface, for example. The rear case 30 e has its open front surface butt-joined to the open rear surface of the front case 30 d via a sealing material 30 m with screws 30 p placed through holes 30 n of the flange part 30 k , to be fixed to the front case 30 d by the screws 30 p.

As shown in FIGS. 4 to 8 , for example, the lens cover 31 includes a cylindrical part 31 a to be mounted on the holder part 30 g of the front case 30 d , with a light-shielding part (light-shielding member) 31 b provided in part of a front-end opening of the cylindrical part 31 a , and an engagement part 31 c for engaging the front case 30 d provided on a rear-end opening of the cylindrical part 31 a.

The light-shielding part 31 b is formed to cover part (upper peripheral area in this case) of the periphery of an opening surface of the front-end opening of the cylindrical part 31 a , and is formed to project toward the front at the side of its peripheral end 31 d which is identical to the mask image Gm in shape. That is, the light-shielding part 31 b is arranged in a range corresponding to the mask image Gm within the angle of view of the imaging lens 30 c , with the lens cover 31 being mounted on the front case 30 d as described later, to shield part of incident light from the exterior.

The engagement part 31 c includes a fitting part 31 e that fits to the first half of the case part 30 f of the front case 30 d , with engagement pieces 31 f extending toward the rear from side surface portions (upper side surface portion and lower side surface portion in this case) of the fitting part 31 e . Each of the engagement pieces 31 f is provided with an engagement hole 31 g that engages the engagement protrusion 30 i of the front case 30 d.

The lens cover 31 thus formed is mounted on the camera 3 with the holder part 30 g of the front case 30 d housed and arranged in its cylindrical part 31 a , and the first half of the case part 30 f of the front case 30 d fitting into its fitting part 31 e . In this mounting state, the light-shielding part 31 b of the lens cover 31 is arranged in the range corresponding to the mask image Gm within the angle of view of the imaging lens 30 c , and the engagement holes 31 g of the engagement pieces 31 f of the lens cover 31 engage the engagement protrusions 30 i of the camera 3 , to fix the lens cover 31 to the camera 3 .

In the vehicle-mounted camera system 1 thus configured, the picked up image G of the camera 3 has the mask image Gm superimposed on part (e.g. the upper area G 1 of the picked up image G shown in FIG. 3 ) thereof by the superimposition circuit 5 , to be displayed on the display device 7 . At this time, out of incident light which enters the angle of view of the imaging lens 30 c , incident light which enters the range corresponding to the mask image Gm is shielded by the light-shielding part 31 b of the lens cover 31 and thus is not received by the imaging element 30 a , and only incident light which enters a range not corresponding to the mask image Gm is received by the imaging element 30 a via the imaging lens 30 c , to image the picked up image G. The result is that the area corresponding to the mask image Gm on an imaging surface of the imaging element 30 a does not receive much of incident light from the exterior (high-luminance incident light), which prevents the occurrence of only a smear in an area without the mask image Gm on the picked up image G. Further, as incident light from outside the angle of view is substantially shielded by the light-shielding part 31 b of the lens cover 31 , the imaging element 30 a does not receive incident light that causes stray light or a ghost, which prevents the occurrence of stray light or a ghost on the picked up image G.

According to the vehicle-mounted camera system 1 thus configured, because the light-shielding part 31 b is arranged in the range corresponding to the mask image Gm within the angle of view of the imaging lens 30 c in its camera 3 , ( 1 ) the light-shielding part 31 b can be secured as large as possible while keeping the part 31 b from appearing on the picked up image G, (2) high-luminance light which enters the range corresponding to the mask image Gm within the angle of view can be shielded so as not to be received by the imaging element 30 a , thus preventing the occurrence of only a smear in an area without the mask image Gm on the picked up image G, and (3) the light-shielding part 31 b , which is arranged within the angle of view of the imaging lens 30 c , can be formed over a large area, to substantially shield incident light from outside the angle of view, thus substantially reducing a ghost and stray light.

Further, since the light-shielding part 31 b is formed to project toward the front at the side of its peripheral end 31 d , unnecessary exterior light can be shielded efficiently by shielding as much incident light from the front as possible.

Moreover, because the mask image Gm is superimposed on the upper area G 1 of the picked up image G, and the light-shielding part 31 b is arranged in the upper area G 1 of the angle of view of the imaging lens 30 c , external light (high-luminance incident light, or incident light that causes a ghost and stray light) which enters the upper area G 1 of the angle of view of the imaging lens 30 c can be shielded appropriately.

Although the light-shielding part 31 b is arranged in the upper peripheral area on the front-end opening surface of the lens cover 31 (namely, the upper area within the angle of view of the imaging lens 30 c ) in this embodiment because the mask image Gm is superimposed on the upper area G 1 of the picked up image G, the arrangement position of the light-shielding part 31 b may be determined depending on the superimposition position of the mask image Gm. When the mask image Gm is superimposed on a lower area of the picked up image G, for example, the light-shielding part 31 b may be arranged in a lower peripheral area on the front-end opening surface of the lens cover 31 (namely, the lower area within the angle of view of the imaging lens 30 c ).

While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous modifications and variations can be devised without departing from the scope of the invention.