The present disclosure relates to an imaging device.
Recently, vehicles are equipped with an imaging device (hereinafter, referred to as a camera) for capturing an image of the surround of the vehicle.
Generally, a method in which a zoom lens is used (for example, see Patent Literature (PTL) 1) is known as a method for obtaining images with different angular fields (angles of views) by using a camera.
PTL 1: Japanese Unexamined Patent Publication No. 2007-43248
The present disclosure provides an imaging device capable of ensuring high image quality while reducing the mounting space and the cost.
An imaging device according to the present disclosure includes a multifocal lens switchable between a plurality of types of angular fields, an angular field controller, an image sensor, a signal processor, and an image processor. The angular field controller receives angular field information indicating an angular field used for capturing an image, and controls the angular field of the multifocal lens based on the angular field information. The image sensor converts light passing through the multifocal lens into an electrical signal. The signal processor converts the electrical signal into an image signal. The image processor receives the angular field information and the image signal, performs predetermined image processing on the image signal based on a parameter which is predetermined in accordance with the angular field information, and externally outputs the image data obtained by the image processing.
According to the present disclosure, it is possible to ensure high image quality while reducing the mounting space and the cost.
Prior to description of an embodiment of the present disclosure, problems in conventional imaging devices will be briefly described. A camera including a zoom lens is not suited for mounting to the vehicle due to an increased number of lenses or increased sizes of the lenses.
A technique to obtain images with different angular fields by using cameras mounted to a vehicle includes, for example, the following two techniques (hereinafter, referred to as a first technique and a second technique).
According to the first technique, a wide angle camera and a narrow angle camera are mounted to a vehicle to obtain a wide angle image using the wide angle camera and the narrow angle image using the narrow angle camera.
In the second technique, one wide angle camera is mounted to a vehicle, and a narrow angle image is obtained by clipping a predetermined range from the wide angle image captured by the wide angle camera and enlarging the clipped range.
However, in the first technique, space for mounting two cameras is required.
Moreover, in the second technique, the narrow angle image obtained by the enlarging has a decreased resolution. In particular, when the difference in angular field between the wide angle image and the narrow angle image is twice or greater, the resolution greatly decreases. In order to ensure the image quality of the narrow angle image, a measure, such as using a high-pixel sensor, is required, which leads to an increased cost.
Therefore, there is a demand for a technique which can ensure high image quality without requiring a plurality of cameras with different angular fields, a high pixel sensor and the like. Note that there is a demand for such a technique not only in the case of mounting a camera to a vehicle, but also in the case of mounting a camera to a limited space.
Hereinafter, an embodiment according to the present disclosure will be described with reference to the drawings.
<Configuration of Imaging Device 100>
First, a configuration of imaging device 100 according to an embodiment will be described with reference to
Imaging device 100 is mounted to a vehicle to capture an image of the area surrounding the vehicle. Imaging device 100 includes lens unit 1, image sensor (solid-state imaging element) 2, signal processor 3, image processor 4, and angular field controller 5.
Lens unit 1 includes a multifocal lens which is switchable between a plurality of types of angular fields (angles of views). In the present embodiment, as an example, lens unit 1 includes a bifocal lens which is switchable between two types of angular fields, a wide angle (wide side) and a narrow angle (tele side). The wide angle which is a first angular field is, for example, a horizontal angle of 180°, and the narrow angle which is a second angular field, is, for example, a horizontal angle of 60°. The details of the configuration of lens unit 1 will be described later with reference to
Image sensor 2 converts light passing through the bifocal lens (first group lens 11, second group lens 12, and third group lens 13 illustrated in
Signal processor 3 receives the electrical signal from image sensor 2, converts the electrical signal to an image signal, and outputs the converted image signal to image processor 4.
Image processor 4 receives the angular field information indicating the angular field used for capturing an image, and selects a parameter used for image processing, based on the angular field information. The image processing includes, for example, clip processing and distortion correcting processing. The clip processing is processing for clipping a predetermined area from the captured image in the image signal. The distortion correcting processing is processing for correcting the distortion of the captured image in the image signal.
Here, the angular field information and the parameters will be described.
The angular field information indicates, for example, a wide angle or a narrow angle. Examples of the output source of the angular field information include a switch (not illustrated). The switch receives an operation made by a user (for example, a driver) for instructing a desired angular field. Upon receiving the user operation, the switch outputs the angular field information indicating the details of the user instruction (wide angle or narrow angle).
Alternatively, the angular field information may be output from an engine control unit or electronic control unit (ECU) which is not illustrated. For example, when the ECU detects that the shift lever is operated into the reverse position, the ECU outputs the angular field information indicating a wide angle.
The angular field information described above is output, as illustrated in
As the parameters, a parameter used for image processing performed on the image captured at a wide angle (hereinafter, referred to as a wide angle parameter) and a parameter used for image processing performed on the image captured at a narrow angle (hereinafter, referred to as a narrow angle parameter) are set in advance.
The wide angle parameter and the narrow angle parameter are necessary for executing, for example, clip processing and distortion correcting processing, and are set in accordance with the mounting position of imaging device 100 (such as the height from the ground) or the angel (such as depression angle or elevation angle). Since these parameters are well known, the detailed descriptions thereof will be omitted.
The wide angle parameter and the narrow angle parameter may be stored in image processor 4 itself, or may be read from a storage device (not illustrated) by image processor 4.
The angular field information and the parameters have been described. Image processor 4 is now described again.
Image processor 4 selects the wide angle parameter, when the angular field information indicates a wide angle. In contrast, image processor 4 selects the narrow angle parameter when the angular field information indicates a narrow angle.
Image processor 4 then receives the image signal from signal processor 3, performs image processing using the selected parameter, and outputs the image data obtained by the image processing to an external predetermined device (not illustrated). Examples of the predetermined device mentioned here include a display, an electronic mirror and a storage device which are mounted to a vehicle.
Image processor 4 may determine the output destination of the image data, based on the angular field information. For example, when the angular field information indicates a wide angle, image processor 4 may output the image data to the display, and when the angular field information indicates a narrow angle, image processor 4 may output the image data to the electronic mirror.
Angular field controller 5 receives the angular field information, and controls the angular field of lens unit 1, based on the angular field information. Specifically, depending on whether the angular field information indicates a wide angle or a narrow angle, angular field controller 5 instructs, to actuator 14 (see
The configuration of imaging device 100 has been described above.
Imaging device 100 described above is mounted at a predetermined position inside or outside the vehicle compartment. For example, imaging device 100 is disposed on the ceiling (roof), rear window, trunk, door mirror or front grille of a vehicle to capture an image surrounding the vehicle (such as frontward, sideward, and rearward of the vehicle).
<Configuration of Lens Unit 1>
Next, a configuration of lens unit 1 illustrated in
As illustrated in
Light L passes through first group lens 11, second group lens 12, and third group lens 13 in this order, and forms an image at image sensor 2 (see
First group lens 11 and third group lens 13 are fixed in place. Each of first group lens 11 and second group lens 12 may include a plurality of lenses. Moreover, third group lens 13 may include a single lens.
In contrast, second group lens 12 is movable between first group lens 11 and third group lens 13 along an optical axis. Specifically, second group lens 12 is movable from the position illustrated in
In the present embodiment, the position of second group lens 12 illustrated in
Coil 16 is fixed to the top part of second group lens 12. Coil 16 is disposed so as to oppose permanent magnet 15.
Permanent magnet 15 is disposed above coil 16. Permanent magnet 15 has, for example, a north pole (N pole) on the right side in the figures and a south pole (S pole) on the left side in the figures. Permanent magnet 15 is disposed along the direction in which second group lens 12 moves.
Actuator 14 is a linear motor actuator, and causes coil 16 to function as an electromagnet by applying current to coil 16. Here, actuator 14 applies current to coil 16 in the direction instructed by angular field controller 5.
For example, when the angular field information indicates a wide angle, angular field controller 5 instructs a first direction to actuator 14. The first direction is a direction in which current flows where the upper part of coil 16 serves as an S pole and the lower part of coil 16 serves as an N pole.
Upon receiving the instruction, actuator 14 applies current to coil 16 in the first direction. Accordingly, as illustrated in
Movement of second group lens 12 to the wide angle capturing position in this manner allows an image to be captured at a wide angle. In this case, as described above, image processor 4 performs, for example, the clip processing and the distortion correcting processing by using the wide angle parameter, and outputs the resultant image data to the display, for example.
In contrast, for example, when the angular field information indicates a wide angle, angular field controller 5 instructs a second direction to actuator 14. The second direction is opposite to the first direction, and is the direction in which current flows where the upper part of coil 16 serves as an N pole, and the lower part of coil 16 serves as an S pole.
Upon receiving the instruction, actuator 14 applies current to coil 16 in the second direction. Accordingly, as illustrated in
Movement of second group lens 12 to the narrow angle capturing position in this manner allows an image to be captured at a narrow angle. In this case, as described above, image processor 4 performs, for example, the clip processing by using the narrow angle parameter, and outputs the resultant image data to, for example, an electronic mirror.
The configuration of lens unit 1 has been described above.
<Operation and Effect of Imaging Device 100>
As described above, when an image is to be captured at the wide angle, imaging device 100 moves second group lens 12 to the predetermined wide angle capturing position to capture the image, and performs image processing by using the wide angle parameter. Moreover, when an image is to be captured at the narrow angle, imaging device 100 moves second group lens 12 to the predetermined narrow angle capturing position to capture the image, and performs image processing by using the narrow angle parameter.
In other words, since imaging device 100 is capable of performing both wide angle image capturing and narrow angle image capturing, a plurality of imaging devices with different angular fields are not required in the vehicle, which leads to a reduction in mounting space for the imaging device(s).
Moreover, imaging device 100 does not require processing for clipping a predetermined range from an image obtained by wide angle capturing and enlarging the clipped region. Accordingly, it is possible to reduce cost for measure to prevent that the resolution is reduced due to such processing (for example, employing of a high-pixel sensor).
Moreover, imaging device 100 performs image processing by using the wide angle parameter on the image captured at the wide angle, and performs image processing by using the narrow angle parameter on the image captured at the narrow angle. Accordingly, high image quality can be ensured for each image.
<Variation>
The present disclosure is not limited to the above embodiment, but many variations are possible. Each variation will be described below.
For example, the case where imaging device 100 is for mounting to a vehicle has been described in the above embodiment as an example, but the present disclosure is not limited to such an example. For example, imaging device 100 may be disposed at a place other than a vehicle (for example, a place where the mounting space is limited).
Moreover, for example, in the above embodiment, the case where lens unit 1 is switchable between two types of angular fields has been described. However, lens unit 1 may be switchable between three or more types of angular fields.
Moreover, for example, the optical axis adjustment and the focus adjustment for setting the wide angle capturing position and the narrow angle capturing position may be performed by screw clamps using springs. This example will be described with reference to
Imaging module 30 includes lens unit 1, sensor (circuit) board 17, and drive (circuit) board 18. For example, image sensor 2, a processor which functions as signal processor 3 (not illustrated), and a processor which functions as image processor 4 (not illustrated) are disposed on sensor board 17. For example, a processor which functions as angular field controller 5 (not illustrated) is disposed on drive board 18. In other words, imaging module 30 is an example of imaging device 100.
As illustrated in
As illustrated in
Moreover, for example, imaging module 30 illustrated in
Imaging module 30 illustrated in
As illustrated in
Moreover, as illustrated in
The imaging device according to the present disclosure is suitable for capturing images at a plurality of angular fields.
Number | Date | Country | Kind |
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2016-171092 | Sep 2016 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2017/016130 | 4/24/2017 | WO | 00 |