JPH0961885A - In-vehicle camera device - Google Patents

Abstract

(57) Abstract: In a vehicle-mounted camera device, harmful reflected light reflected and incident on a windshield is removed. A polarizing filter is fixed to a diaphragm blade that forms a diaphragm hole that defines the amount of light from a lens. This polarization filter is adjusted in a direction in which reflected light from the windshield of the vehicle is removed. The smaller the aperture diameter of the aperture hole, the greater the area ratio covered by the polarization filter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted camera device which is fixed to a vehicle and picks up an image in front of the vehicle.

[0002]

2. Description of the Related Art Conventionally, a vehicle such as an automobile is equipped with a camera using a solid-state image sensor such as a CCD (charge coupled device) to detect a preceding vehicle or an obstacle, and even recognize a white line drawn on a road. Has been done. In such a case, since it is necessary to capture the situation from the immediate vicinity of the subject vehicle to a distant place, the camera is usually mounted at a relatively high position in front of the vehicle interior. FIG. 4 shows an example in which the camera is mounted on the vehicle. In this figure, 100 is the ceiling of the car,
101 is a front monitoring camera mounted near the front of the vehicle on this ceiling, 102 is a lens portion of the camera 101,
103 is the windshield of this car, 104 is the dashboard, 105 is the upper surface of the dashboard 104, 1
06 indicates the sun.

[0003]

However, when the camera is installed in a relatively high place in the front of the vehicle compartment as described above, the light reflected by the inner surface of the dashboard and the windshield may enter the lens of the camera. is there. That is,
When the sun 106 is at the position shown in FIG. 4, the incident light L0 is reflected by the upper surface 105 of the dashboard 104 and becomes L1 which is then incident on the inner surface of the windshield 103 and is reflected there again to L2. And enters the lens unit 102 of the camera. The reflected light significantly reduces the contrast of the image obtained by the camera to make it unclear, and causes so-called reflection from the windshield. This was particularly noticeable when a highly reflective object such as a white towel or books was placed on the upper surface of the dashboard. As a countermeasure against this, for example, a long hood may be contacted between the lens of the camera and the windshield to block the reflected light from the windshield. FIG. 5 shows an example in which reflected light is removed by a hood. However, in this case, although it is possible to completely block the reflected light, a long hood 107 extending over the lens portion 102 and the windshield 103 is required, which causes a problem in appearance and also has a problem of hindering the driver's forward vision. It was

Further, since the subject is very bright in the daytime in fine weather, the aperture diameter of the aperture hole is very small. In such a case, if the diaphragm blade of the camera is moved to adjust the diaphragm hole, even if the diaphragm blade is slightly displaced, the change rate of the aperture diameter of the diaphragm hole becomes very large. Therefore, in such a situation, if an attempt is made to adjust the aperture diameter of the diaphragm hole by feedback control, the aperture diameter cannot be stabilized by repeatedly increasing or decreasing the aperture diameter so-called hunting. There was a problem that it caused a phenomenon.

Also, the light is bent at the edge of the aperture hole,
A so-called diffraction phenomenon occurs regardless of the aperture diameter,
This is a cause of lowering the sharpness of the image obtained by the camera. The decrease in image clarity due to this diffraction phenomenon is relatively small when the aperture diameter of the aperture hole is relatively large and the total amount of light is large, but when the aperture diameter of the aperture hole is relatively small. However, there is a problem in that the total amount of light is small and the effect cannot be ignored.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to obtain a vehicle-mounted camera device capable of removing reflected light from a windshield without increasing the size of the entire device. I am trying.

Another object of the present invention is to provide a vehicle-mounted camera device capable of stabilizing the aperture diameter of a diaphragm hole even when a subject is very bright.

Another object of the present invention is to provide a vehicle-mounted camera device capable of alleviating a decrease in image sharpness due to a diffraction phenomenon.

[0009]

A vehicle-mounted camera device according to the present invention includes a lens for collecting light from the front of the vehicle,
From the windshield of the vehicle, the diaphragm blade composed of a plurality of opaque plates that form the diaphragm hole that regulates the amount of light from this lens, the diaphragm hole adjusting means that moves the diaphragm blade to change the aperture diameter of the diaphragm hole. It is equipped with a polarizing filter that is adjusted in the direction of removing the reflected light of the lens and fixed to a part of the diaphragm blades, and an image pickup means that receives the light collected by the lens and images the front of the vehicle. The smaller the aperture is, the larger the area ratio covered by the polarization filter is.

Further, the vehicle-mounted camera device according to the present invention has two polarizing filters, one of which is adjusted to remove the reflected light from the windshield of the vehicle and the other of which is provided. The adjustment is made in the orthogonal direction.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. FIG. 3 shows an example in which the vehicle-mounted camera device of the present invention is mounted on a vehicle. In the figure, 10 is a ceiling of an automobile, 11 is a front monitoring camera mounted near the front of the vehicle on this ceiling, 12 is a lens portion as a lens of the camera 11, 13 is a windshield of the automobile,
Reference numeral 14 denotes a dashboard, 15 denotes an upper surface portion of the dashboard 14, and 16 denotes the sun. Although not shown, the light incident from the lens unit 12 is condensed by the lens unit 12 and the amount of light is regulated by a diaphragm device described later, and is incident on an image pickup device (not shown) which is a CCD. To do. The CCD receives this light and processes it to obtain an image in front of the vehicle.

FIG. 1 is an exploded perspective view of a diaphragm device of a vehicle-mounted camera device according to the present invention. In the figure, reference numerals 1 and 2 denote diaphragm blades made of a black opaque plastic thin plate, each of which has cutout portions 1a and 2a for forming diaphragm holes for defining the amount of light from the lens portion 12.
3 is a film-like polarizing filter as a polarizing filter,
It is fixed to the diaphragm blade 1 by a method such as adhesion or ultrasonic welding in a state of covering a part of the notch 1a. Here, since the polarization filter has directionality as is well known, the polarization plane is adjusted to a direction in which the harmful reflected light L2 from the windshield 13 can be removed and fixed to the diaphragm blade 1. The direction in which the harmful reflected light L2 from the windshield 13 can be removed is naturally determined if the mounting position of the camera 11 and the imaging direction of the camera 11 are determined. That is, since the relative angle between the harmful reflected light L2 and the optical axis of the lens portion 12 of the camera 11 is fixed when the camera 11 is fixed, the harmful reflected light L2 incident from this fixed direction is removed. The film-shaped polarizing filter 3 may be adjusted in the direction and fixed. Four
Is a servo motor for driving these diaphragm blades 1, 2. Reference numeral 5 designates the driving force of the servo motor 4 as the diaphragm blades 1,
2 is a lever for transmitting to the servomotor 2. The central portion is fixed to the output shaft of the servomotor 4, and the holes 1b and 2b are provided at both ends.
Has a pin that engages with. This pin and hole 1b, 2b
And constitute an engaging portion. Reference numeral 6 denotes a housing for slidably holding the diaphragm blades 1 and 2. Note that the holes 1b, 2
b, the servo motor 4 and the lever 5 constitute a diaphragm hole adjusting means for changing the opening diameter of the diaphragm hole. The diaphragm device configured as described above is incorporated in the lens unit 12 of the camera 11, and L in the drawing indicates the optical axis of the lens.

FIG. 2 is an explanatory diagram showing how the aperture diameter of the aperture hole changes. The servomotor 4 is controlled by a controller (not shown). Based on the brightness of the image obtained by the camera, the controller controls the rotation direction and the rotation angle of the servo motor 4 so that the aperture diameter of the aperture hole is small when the subject is bright and is large when the subject is dark. To do. In this configuration, when the servo motor 4 is driven, the diaphragm blades 1 and 2 move in directions opposite to each other on the plane orthogonal to the optical axis L of the lens. As a result, the overlapping state of the two diaphragm blades changes, and the opening diameter of the diamond-shaped diaphragm hole 7 formed by the notches 1a and 2a provided in each of them can be changed.

In FIG. 2, (a) is a state in which the subject is dark and the aperture hole 7 is opened, (c) is a state in which the subject is bright and the aperture hole 7 is narrowed, and (b) is an intermediate of the above two examples. Shows the general condition. (A) is a state of imaging at night, imaging during traveling in a tunnel, or the like, and the area covered by the film-like polarizing filter 3 is only a part of the opening area of the aperture hole 7. Therefore, in this state, the interposition of the film-shaped polarizing filter 3 has almost no effect. That is, the light transmittance of the polarizing filter is generally 50%.
It is the following. For this reason, when the light from the lens is incident on the polarization filter 3 in a dark state of the subject as shown in (a), the amount of light is significantly reduced, and it becomes difficult to capture an image. However, according to the present invention, as shown in (a), since the film-shaped polarizing filter 3 covers only a part of the opening area, there is substantially no problem. Further, since the reflected light from the windshield 13 is small when the subject is dark as shown in (a), it is said that the windshield 13 is reflected even if the film polarizing filter 3 is not interposed between the lens and the image pickup element. There is no problem.

Now, the ratio of the opening area of the diaphragm hole 7 covered by the film polarizing filter 3 becomes larger as the aperture diameter of the diaphragm hole 7 becomes smaller as shown in FIG. 2, and the diaphragm hole 7 shown in FIG. In this state, the entire opening area of the aperture hole 7 is covered with the film-shaped polarizing filter 3. Therefore, in the state of (c) in which the subject is bright and the problem of reflection from the windshield 13 is likely to occur, harmful reflected light is removed from the light passing through the lens and reaching the image sensor by the action of the film-like polarization filter 3. Be done. That is, since the reflected light from the windshield 13 does not reach the image sensor, a clear image can be obtained.

In (b), the film-like polarization filter 3 partially acts in the intermediate diaphragm state of the above two examples, but since this diaphragm device is incorporated in the lens portion 12 as described above, the image of the image is not displayed. There is no inconvenience such as uneven brightness.

In the first embodiment described above, the diaphragm blade 1
Although the one in which the film-shaped polarization filter 3 is attached is shown, the film-shaped polarization filter 3 may be provided in the diaphragm blade 2. Further, the polarizing filter is not limited to the film shape and may have any shape. In the first embodiment, the type in which the two diaphragm blades move in parallel has been described, but one diaphragm blade may be added and the polarization filter may be attached to this blade. Further, it can be implemented in a so-called "iris diaphragm" type diaphragm device in which three or more diaphragm blades make one circular motion to change the aperture diameter of the diaphragm hole, and the same effect as that of the first embodiment can be obtained. .

The present invention is effective only when applied to, for example, a vehicle-mounted camera device or the like in which the incident angle of reflected light is fixed as described above, and can be applied to all general camera devices. Not a thing. That is, as described above, the polarization filter has directionality, and when the incident angle of the reflected light to be removed changes, the rotation angle of the polarization filter with respect to the optical axis of the lens must be changed accordingly. However, even if a polarizing filter is attached to a general camera, the angle of reflected light incident on the camera varies, and since the camera is not fixed, it is difficult to remove all harmful reflected light. It must be noted that

Next, in the case of using the polarizing filter, in addition to the removal of harmful reflected light described above, the effects of hunting prevention and diffraction phenomenon prevention also occur. This is because the light transmittance of the polarizing filter is generally 50% or less. That is, when the subject is very bright, the aperture diameter of the aperture hole becomes very small, so even with a slight displacement of the aperture blade, the rate of change of the aperture diameter becomes very large, and the aperture diameter is controlled to a desired value. Becomes difficult. Further, the pin of the servo motor 4 and the aperture 1b of the diaphragm blade,
Backlash occurs at the engaging portion of 2b, but as the opening diameter becomes smaller, the effect of the error in the opening diameter due to the backlash cannot be ignored. A controller (not shown) performs feedback control so that the brightness of the image obtained by the camera 11 becomes a desired brightness. However, as the aperture diameter becomes smaller, the above-mentioned factors are more likely to affect the hunting phenomenon. Become. Further, when the aperture diameter of the diaphragm hole is small, the image is deteriorated due to the diffraction phenomenon of light as described above.

However, according to the present invention, when the aperture diameter of the aperture hole becomes small, the influence of the film-like polarization filter 3 becomes large and the light transmittance becomes low. Therefore, even when the subject is bright, the aperture diameter of the aperture hole becomes large. Is not so small. Therefore, when the diaphragm blades 1 and 2 are slightly displaced or backlash occurs between the servo motor 4 and the diaphragm blades 1 and 2, the brightness of the image obtained by the camera 11 changes so much. Will not do. Therefore, it is possible to prevent the hunting phenomenon from occurring. Further, if the aperture diameter of the aperture is more than a certain value, the ratio of the amount of light passing through the edge of the aperture and causing the diffraction phenomenon to the amount of light passing through the center of the aperture and not causing the diffraction phenomenon is large. Therefore, the image formed by the camera 11 is not deteriorated. Further, as described above, when the aperture diameter of the aperture hole is large, the influence of the film-like polarization filter 3 is small, so that the problem of insufficient light quantity does not occur when the subject is dark.

Embodiment 2 FIG. Although only one film-shaped polarizing filter is used in the first embodiment, a plurality of film-shaped polarizing filters may be used. Specifically, in the first embodiment, the film-shaped polarizing filter 3 is adjusted in the direction in which the harmful reflected light from the windshield 13 is removed and fixed to the diaphragm blade 1, but in the second embodiment, the diaphragm blade 2 is further fixed. Notch 2
A film-shaped polarizing filter is fixed to a similarly to the diaphragm blade 1. However, the point to note here is
The film-shaped polarizing filter fixed to the diaphragm blade 2 is not mounted in exactly the same manner as that mounted on the diaphragm blade 1, but the direction of the film-shaped polarizing filter is rotated with respect to the optical axis of the lens, This means that the film-shaped polarizing filter was mounted by adjusting it in the direction orthogonal to the direction of the film-shaped polarizing filter. It is known that when two polarizing filters are stacked so that their directions are orthogonal to each other, the light transmittance is drastically reduced. Therefore, by arranging them so that the polarization planes of the polarization filters are orthogonal to each other, it is possible to further suppress the effects of the hunting phenomenon and the diffraction phenomenon.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a diaphragm device of a vehicle-mounted camera device according to the present invention.

FIG. 2 is an operation explanatory view of the diaphragm device of the vehicle-mounted camera device of the present invention.

FIG. 3 is a configuration diagram showing an example in which the vehicle-mounted camera device of the present invention is mounted on a vehicle.

FIG. 4 is a configuration diagram showing an example in which a conventional vehicle-mounted camera device is mounted on a vehicle.

FIG. 5 is a configuration diagram showing an example of a conventional countermeasure for removing harmful reflected light.

[Explanation of symbols]

1, 2: diaphragm blades, 1a, 2a: notches, 1b, 2
b: hole, 3: film-shaped polarizing filter, 4: servo motor, 5: lever, 6: housing, 7: aperture hole, 10: ceiling,
11: camera, 12: lens part, 13: windshield, 14: dashboard, 15: upper surface part of dashboard, 16: sun, 100: ceiling, 101: camera, 1
02: lens part, 103: windshield, 104: dashboard, 105: upper part of dashboard, 10
6: sun

Claims (2)

[Claims] 1. A lens for condensing light from the front of a vehicle, diaphragm blades composed of a plurality of opaque plates forming diaphragm holes for defining the amount of light from the lens, and moving the diaphragm blades to obtain the above. A diaphragm hole adjusting means for changing the aperture diameter of the diaphragm hole, a polarizing filter fixed in a part of the diaphragm blade and adjusted in a direction for removing reflected light from the windshield of the vehicle, and condensed by the lens. An in-vehicle camera device, comprising: an image pickup unit that receives light and images the front of the vehicle, and the smaller the aperture diameter of the aperture hole, the greater the area covered by the polarization filter. 2. A polarizing filter having two polarizing filters, one of which is adjusted in a direction for removing reflected light from a windshield of a vehicle and the other of which is adjusted in a direction orthogonal to the one. The vehicle-mounted camera device according to claim 1, which is provided.