JP2001005054A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device made small in size and light in weight and inexpensive. SOLUTION: This device is composed of an image pickup lens array 1 constituted of plural image pickup lenses 1a, an imaging device 2 such as a CCD or a CMOS sensor and a field lens 3a, and the lens array 1 is disposed on the image pickup surface side of the device 2 and further a field lens 3a is disposed on the image pickup surface side of the lens array 1. By constituting the lens array 1 of plural image pickup lenses 1a, the angle of view required for one lens 1a is reduced, whereby the requirement of compensating aberration is reduced, so that the image pickup device which is small in size and light in weight and inexpensive is realized by using the lens array 1 consisting of plural lenses 1a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus for picking up an image with an image pickup device such as a CCD or a CMOS sensor.

[0002]

2. Description of the Related Art Conventionally, a camera (silver halide camera) captures an image by projecting an image on a film with a monocular lens and exposing the film to light. The twin-lens reflex camera has two lenses, one is a finder lens, and only one lens is used for actual imaging.

[0003] In recent years, digital cameras have become very popular (cameras which directly convert an image into digital data using an electronic image sensor instead of film and record the image as image data).
The principle of imaging is the same for imaging devices such as video cameras and video cameras, and an image is captured by a single imaging lens.

On the other hand, Japanese Patent Application Laid-Open No. Hei 6-6680 discloses that two ordinary imaging lenses are arranged, images are taken so that different fields of view are slightly superimposed, and the superimposed portion is subjected to a correlation operation process to shift the two images. A compound-eye imaging device that corrects the above and obtains a panoramic image has been reported.

[0005]

A single imaging lens requires a large angle of view (for example, an ordinary 3).
In the case of a standard lens used for a 5mm SLR camera,
The angle of view reaches about 60 degrees), and the demand for aberration correction for the imaging lens is severe. Therefore, the imaging lens is generally composed of five to six or more lenses. Therefore, the camera was large and heavy, and the cost was high.

In the case of a compact camera, the demand for aberration correction has been reduced by reducing the lens diameter and increasing the F-number, and downsizing has been attempted by reducing the number of lenses, but there is a limit.

[0007] A digital camera has a similar problem. That is, in the case of a digital camera, the imaging area is smaller than that of a silver halide camera using 35 mm film, and an imaging lens with a shorter focal length can be used to obtain the same angle of view (imaging range). For example, one in 2.7
When using an inch CCD sensor (a type of solid-state image sensor), an imaging lens with a focal length of about 6 mm can provide an angle of view similar to that obtained with an imaging lens with a focal length of 40 mm of a normal silver halide camera. Can be Therefore, a considerable size reduction can be expected even in comparison with a conventional compact camera.

However, actually, before the solid-state imaging device,
A color filter for separating and obtaining the image information of the three primary colors (R, G, B) and a low-pass filter are necessary to obtain matching between the spatial frequency characteristics of the imaging lens and the solid-state imaging device. For this purpose, it is necessary to make the light beam that reaches each pixel of the image sensor substantially perpendicularly incident, and the imaging lens is required to be telecentric (the main light beam of each image height is vertically incident on the image sensor). For example, in the case of a normal imaging lens (non-telecentric), the angle of view is 3 on one side with a standard lens.
It becomes 0 degree or more, and the principal ray is inclined up to about 30 degrees. A large number of lenses are required to make a telecentric optical system. For example, even a lens having a focal length of 6 mm has a length of 25 mm or more from the lens end surface to the imaging surface. Therefore, there has been a limit in reducing the size, weight, and cost of a digital camera using an electronic image sensor.

In the above-mentioned Japanese Patent Application Laid-Open No. 6-6680,
Although a compound-eye imaging apparatus is disclosed, it is intended to obtain a panoramic image using two ordinary imaging lenses, and cannot achieve a reduction in size and weight. In addition, since two images are joined together by using image correlation processing, there is a disadvantage that image processing takes time. It is not suitable for joining images by a large number of imaging lenses as in the present invention described later.

JP-A-7-67020 and JP-A-Hei-1
Japanese Patent Application Laid-Open No. 0-107975 discloses a compound-eye optical system in which a plurality of imaging lenses are arranged such that each optical axis is emitted from substantially one point. However, since each lens uses an imaging lens of a normal specification and has a large angle of view, it is not suitable for reduction in size and weight. In addition, since the distortion is not corrected, there is a disadvantage that the joining processing of the images becomes complicated.

The present invention has been made in view of the above circumstances, and has as its object to provide a small, lightweight, low-cost imaging device.

[0012]

The present invention provides an image pickup device,
A lens array having a plurality of imaging lens units disposed on the imaging surface side of the imaging element, wherein each imaging lens unit of the lens array has a different imaging range. I do.

[0013] The present invention is further characterized by further comprising a field lens for allowing light rays to enter the lens array at a predetermined angle of view.

Each of the imaging lens units of the lens array is disposed on a virtual spherical surface, and the image pickup element is disposed on a concentric virtual spherical surface having a smaller radius than the spherical surface so as to correspond to each of the imaging lens units. It is characterized by being provided.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of an image pickup apparatus according to the present invention will be described below with reference to the drawings. In the present embodiment, an example will be described in which the present invention is applied to a digital camera that has become very popular instead of a silver halide camera. It should be noted that application to a video camera for capturing a moving image can be realized with a substantially similar configuration.

[First Embodiment] FIG. 1 is a schematic diagram showing an optical system used in an image pickup apparatus (multi-view digital camera) according to a first embodiment. As shown in FIG. 1A, an optical system includes an imaging lens array 1 composed of a plurality of imaging lenses 1a (imaging lens unit), a CCD, and a CM.
It comprises an image sensor 2 such as an OS sensor and a field lens 3a. By using the imaging lens array 1 including a plurality of imaging lenses 1a, a small, lightweight, low-cost imaging device is realized.

An imaging lens array 1 is arranged on the imaging surface side of the imaging device 2, and a field lens 3a is arranged on the imaging surface side of the imaging lens array 1. Field lens 3a
Is for causing an image in a predetermined direction to enter the imaging lens array 1. The optical axis of each imaging lens 1a is substantially perpendicular to the imaging device 2. Note that it is not always necessary to be vertical. By introducing the field lens 3a, the imaging lens array 1 can be constructed in a planar shape. Therefore, the production of the imaging lens array 1 is facilitated, and it is effective for reducing the thickness of the apparatus. Note that the imaging lens array 1 and the field lens 3a may be integrally formed. The field lens 3 shown in FIG.
As shown in FIG. 1A, a convex lens, ie, a lens having positive power, or a concave lens, ie, a lens having negative power, such as a field lens 3b shown in FIG.

A low-pass filter 4 is provided between the imaging lens array 1 and the imaging device 2 as needed. Further, a light-shielding plate 5 as shown in FIG. 2 is provided on the imaging element 2 in close contact with the imaging surface (not shown in FIG. 1). The light-shielding plate 5 is provided so that an image formed by each imaging lens 1a constituting the imaging lens array 1 can be used by the adjacent imaging lens 1
The image is not overlapped with the image a and input to the image sensor 2. That is, each imaging lens 1a of the imaging lens array 1
Are configured to have different imaging ranges.

In the case of the optical system having the configuration shown in FIG. 1A or in the case of using a double-imaging lens (a lens for obtaining an erect image) as the imaging lens, the image obtained by each imaging lens 1a is , Can be connected as it is. On the other hand, FIG.
In the case of (b), it is necessary to rotate by 180 degrees and join together.

As shown in FIG. 1, the imaging lens array 1
Since the imaging lens 1a is configured by a plurality of imaging lenses 1a, the angle of view of each imaging lens 1a is equal to the angle of view of the imaging lens used in an imaging apparatus using a normal single-lens imaging lens. It is the angle divided by the number of lenses 1a. For example, if there are six imaging lenses 1a, one sixth is obtained.
become. Therefore, the angle of view required for each imaging lens 1a is very small, the requirements for aberration correction are very loose, and a single lens can be used. Of course, if higher performance is required, a gradient index lens may be used.

For this reason, the digital camera can be configured to be very thin as a whole, including the field lens. When the digital camera is configured to be very thin, an optical finder cannot be provided, and a display device (such as an LCD) is used as the finder.

Hereinafter, specific numerical values will be described.

FIG. 3 shows an example of the image pickup device 2 and the image pickup lens 6 which are mounted in a normal digital camera. 3A shows a diagonal portion of the image sensor 2, FIG. 3B shows a lateral portion, and FIG. 3C shows a side surface of the vertical portion.

For example, an image sensor 2 having a size of 2.7 inches is used.
In the case of, as shown in FIG.
It is 76 mm x 4.32 mm and the diagonal is 7.2 mm.
If the focal length of the imaging lens is 5.5 mm, horizontal, vertical,
The angle of view on one side in each diagonal is about 27.64 degrees,
21.44 degrees and 33.21 degrees. In this case, the imaging lens is formed of a plurality of lenses in order to use a telecentric optical system and satisfactorily correct aberrations corresponding to a large angle of view. Accordingly, the overall length of the imaging lens becomes longer, and the distance between the end surface of the imaging lens and the imaging device is about 2
It is about 5 mm. In the case of this example, the effective diameter of the imaging lens is 2 mm and the F number is 2.8.

FIG. 4 shows an image pickup device 2 and an image pickup lens 1 mounted in a multi-view digital camera according to the present invention.
An example is shown. Here, as shown in FIG. 4A, the number of imaging lenses 1a in the imaging lens array 1 is eight.
× 6. The lens outer shape of each imaging lens 1a is shown in FIG.
It becomes 0.72 mm x 0.72 mm as shown in (b). The size of the imaging surface corresponding to each imaging lens 1a on the imaging device which can be secured to the maximum is also 0.72 mm × 0.7
2 mm (for simplicity of explanation, the processing margin in the case of actually manufacturing is not considered). The focal length of each imaging lens 1a is 5.5 mm. The angle of view of each imaging lens 1a is about 7.5 × 7.5 degrees (the diagonal direction is
10.58 degrees).

The total angle of view of the conventional imaging lens is shown in FIG.
As described above, about 55.28 (27.64 ×
2) x 42.88 (21.44 x 2) degrees, and the same angle of view as this angle of view is obtained for the multi-view digital camera of the present invention, which is about 7 degrees for each imaging lens 1a. Since each imaging lens 1a can image an angle of view of about 7.5 degrees, this difference is
It can be used to partially overlap the imaging range of each imaging lens 1a. Thereby, each imaging lens 1
The images corresponding to a can be smoothly joined.

In the case of this numerical example, since the focal length is set to 5.5 mm, which is the same as the conventional example, the F-number of each imaging lens 1a is about 7.6, which is a dark lens. Therefore,
Focusing is almost unnecessary. However, it is desirable to make the sensitivity of the image sensor higher.

A numerical example in which the F number is kept at 2.8 is also conceivable. In that case, the focal length of each imaging lens 1a is 2.8 mm. The angle of view of each imaging lens 1a is about 14.6 × 14.6 degrees, and in order to secure the same angle of view as a conventional digital camera, the number of imaging lenses 1a may be 4 × 3. Become. However, in this case, in order to secure the same number of pixels of the image, an image sensor having a pixel interval of 二 is required.

Next, the configuration of a multi-view digital camera according to the present invention is shown in the block diagram of FIG. Note that a commonly mounted mechanism such as a flash is not shown). As shown in FIG. 5, image data is obtained by the imaging lens array 21 and the imaging device 22. Since the image data is composed of a plurality of image data obtained by each imaging lens 1a constituting the imaging lens array 21, it is necessary to perform a joining process.

When the concave field lens 3b shown in FIG. 1B is used, when the image taken by each imaging lens 1a is, for example, a subject shown in FIG.
As shown in FIG. 6B, they are relatively inverted. For this reason, before the joining process, each imaging lens 1
a rotation processing circuit 2 for rotating the image by 180 degrees
3 is required. However, when a field lens in which the image from each imaging lens 1a is not inverted, such as a double-imaging lens, is used, the rotation processing circuit 23 becomes unnecessary (or does not function).

The camera body is provided with a simple image pickup lens 1.
A connection circuit 24 for connecting the plurality of image data obtained in a to one image data is provided. The splicing circuit 24 is for displaying an image as a finder on the display device 25, and has a simple function that eliminates the need for high-definition splicing processing that requires complicated processing. I do. This reduces the signal processing load and reduces size,
Lighter weight and lower cost can be achieved to a higher degree. Further, the load on the battery is reduced, and the battery lasts longer.

The image data obtained by the image sensor 22 is recorded in the recording device 26. This image data may be image data obtained after the rotation processing by the rotation processing circuit 23 or image data before the rotation processing. When recording the image data before the rotation processing, the rotation processing is performed when the image data recorded in the recording device 26 is used. Further, the image data may be recorded after being compressed, or may not be compressed.

Although high-definition image processing can be performed by the digital camera itself, an image processing apparatus is separately prepared. This image processing apparatus can be realized by a personal computer that executes software (program) having an image processing function described later.

When connecting the images obtained by the respective image pickup lenses 1a of the image pickup lens array, it is ideal to connect the boundaries of the respective images as they are. However, in actuality, the processing error of the image pickup lens array 1 and each lens It is necessary to slightly rotate each image to adjust the direction or correct the distortion due to the slight residual distortion.

A method of matching by correlation processing or the like using the obtained image data is conceivable, but it takes a very long time. Therefore, in the first embodiment,
After assembling the imaging lens array 21 and the imaging element 22, once imaging is performed using a measuring chart having vertical and horizontal stripes or a specific pattern, and the obtained image is analyzed.
The rotation of the image by each imaging lens 1a and the setting of the boundary position between the adjacent images are acquired as correction data. It can be said that this correction data is information on deviation from the design value. This is recorded in the recording device 26 of the multi-view digital camera body as information unique to each multi-view digital camera.
The correction data recorded in the recording device 26 is transferred at the same time as, for example, transferring image data from the multi-view digital camera to the image processing device. An image processing apparatus that performs high-definition image processing executes image processing including a joining process of a plurality of image data in consideration of correction data acquired from a multi-view digital camera. Thus, a correct high-accuracy splicing process can be executed irrespective of a manufacturing error for each multi-view digital camera. It should be noted that the correction data recorded in the recording device 26 is
Of course, it is also possible to use it when the 4 executes the joining process.

As described above, in the multi-view digital camera according to the first embodiment, by reducing the angle of view required for one imaging lens 1a, the requirement for aberration correction for the imaging lens array is reduced. Aberration correction is made possible with only one or a small number of lenses. This makes it possible to configure the device very thin. Further, by providing a field lens that assigns an imaging range in which each imaging lens 1a captures an image, each imaging lens 1a of the imaging lens array 1 is provided.
Even if the optical axis is perpendicular to the image sensor, it is possible to image a subject in a direction corresponding to a large angle of view.

[Second Embodiment] Next, an optical system used in the imaging apparatus according to the second embodiment will be described. FIG. 7 is a configuration diagram schematically showing the optical system. As shown in FIG. 7, the optical system includes an imaging lens array 31 in which a plurality of imaging lenses 31a are integrally formed on the surface of a virtual sphere, and a plurality of image sensors arranged on the surface of the virtual sphere having a small radius concentric with the imaging lens array 31. 32. This makes it possible to obtain a very wide angle of view by eliminating the need for the field lens used in the optical system according to the first embodiment. Multiple image sensors 32
Corresponds to a plurality of imaging lenses 31a. In the second embodiment, in the imaging lens array 31, the optical axis of each imaging lens 31a is substantially perpendicular to the imaging device 32. Of course, it does not have to be vertical. Further, between the imaging lens array 31 and the imaging device 32,
A low-pass filter 34 is used if necessary.

The image pickup device 32 has an image pickup surface side as shown in FIG.
7 is provided (not shown in FIG. 7). The light shielding plate 35 is used for the imaging lens array 31.
Is prevented from being input to the image sensor 32 by overlapping with the image of the adjacent imaging lens 31a. That is, each imaging lens 31a of the imaging lens array 1 is configured to have a different imaging range.

When the optical system shown in FIG. 7 is used, images obtained by the respective imaging lenses 31a need to be rotated by 180 degrees and joined together. In addition, the angle of view of each imaging lens 31a is the same as that of the optical system in the first embodiment, and the angle of view of the imaging lens used in an imaging device using a normal single-lens imaging lens is set in the direction of the imaging lens array. It is an angle divided by the number of a certain imaging lens 1a. Therefore, the angle of view required for each imaging lens 31a is very small, the requirements for aberration correction are very mild, and a single lens can be used. Therefore, the digital camera can be configured to be very small as a whole.

In the case of a very small size, an optical finder cannot be provided, and the display device (L
CD, etc.) as a finder.

In the optical system according to the second embodiment, since each imaging lens constituting the imaging lens array 31 captures an image of an inclined object surface, asymmetric distortion occurs. For this reason, in order to simplify the process of joining a plurality of image data obtained corresponding to each imaging lens 31a, each imaging lens 31a corrects asymmetric distortion.

The other components such as the image processing system are performed in the same manner as in the first embodiment, and the description is omitted.

By arranging the imaging lenses 31a constituting the imaging lens array 31 on a virtual spherical surface in this manner, a field lens can be eliminated, and each imaging lens 31a can be corrected for asymmetric distortion. With such a lens, the joining process can be simplified.

[Appendix 1] The imaging apparatus according to claim 1, wherein each of the imaging lens units is integrally joined to form a lens array.

As a result, an extremely thin imaging device can be realized.

[Appendix 2] The imaging apparatus according to claim 1, wherein each of the imaging lens units is a gradient index lens.

As a result, the demand for aberration correction becomes very mild, and a single lens can be used, so that a very thin imaging device can be realized.

[Appendix 3] The image pickup apparatus according to any one of claims 1, 2 and 3, further comprising a light shielding means for limiting a range of an image formed on the image pickup device by each image pickup lens section of the lens array. apparatus.

Thus, even if one image sensor is used for a plurality of image pickup lens units, interference between images obtained by the respective image pickup lens units is eliminated.

(Supplementary Note 4) The imaging apparatus according to claim 1, further comprising means for joining images captured by the imaging lens to each other.

Thus, even if an optical finder cannot be provided to reduce the size of the device, a display device for the finder can be provided and an image captured by the imaging lens can be displayed in real time.

[Appendix 5] The imaging apparatus according to Appendix 4, wherein the field lens has a positive optical power.

Thus, it is not necessary to rotate the image data captured by the respective imaging lenses, and a plurality of images can be connected and displayed as one image.

[Supplementary Note 6] The field lens has negative optical power, and the connecting means rotates the image data captured by each of the imaging lenses by 180 degrees and then connects the image data. 5. The imaging device according to 4.

Thus, even if a field lens having negative optical power is used, a plurality of images obtained by a plurality of imaging lens units can be displayed as one image.

[Supplementary Note 7] The imaging apparatus according to supplementary note 4, wherein the imaging lens is a double-imaging type lens, and the field lens has negative optical power.

Thus, it is not necessary to rotate the image data captured by the imaging lens, and a plurality of images can be displayed as one image.

[Appendix 8] The image pickup apparatus according to claim 3, wherein the image pickup lens section of the image pickup lens array is a lens in which asymmetric distortion is corrected.

As a result, since no asymmetrical curved surface aberration occurs, the image joining process can be easily performed.

[Supplementary Note 9] The imaging apparatus according to Supplementary Note 4, wherein an imaging range of each imaging lens unit of the lens array has a portion overlapping an imaging range of an adjacent imaging lens unit.

As a result, the images captured by the respective imaging lens units can be smoothly connected.

[Supplementary Note 10] The means for joining the images includes means for recording the deviation of the imaging range of each imaging lens unit of the lens array from the design value, and the deviation from the recorded design value. 5. The imaging apparatus according to claim 4, further comprising: means for correcting a joining position of the captured images.

Thus, it is possible to correct the processing error of the lens array and perform high-precision image joining.

[Supplementary Note 11] After assembling the image pickup device and the lens array at a specified position, a specified image is taken from the image pickup device, and a deviation from a design value of an imaging range of each imaging lens unit is recorded. 13. The imaging device according to supplementary note 10, wherein

As a result, high-accuracy splicing can be performed without being affected by manufacturing errors.

[Supplementary Note 12] Image input means having an image sensor configured to have a plurality of different image pickup ranges, means for recording a shift of the image pickup range of the image sensor from a design value, and the image input device An image pickup apparatus, comprising: performing a process of correcting a joining position by using a difference between an image signal recorded by an input unit and a recorded design value, and joining captured images.

This eliminates the need to provide the image input means with a high-precision image processing function, so that the size of the image input means can be reduced.

[0068]

As described above, according to the present invention, the angle of view required for one imaging lens unit is reduced by providing an imaging lens array including a plurality of imaging lens units. Accordingly, the demand for aberration correction for the imaging lens is reduced, so that aberration correction can be performed with a small number of lenses, and a small, lightweight, low-cost imaging apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an optical system used in an imaging apparatus (multi-view digital camera) according to a first embodiment.

FIG. 2 is a view showing an example of a light shielding plate 5 provided in close contact with an image sensor 2.

FIG. 3 is a diagram showing an example of an imaging device 2 and an imaging lens 6 mounted in a normal digital camera.

FIG. 4 is a diagram showing an example of an imaging element 2 and an imaging lens 1 mounted in the multi-view digital camera according to the present invention.

FIG. 5 is a block diagram showing a configuration of a multi-view digital camera according to the present invention.

FIG. 6 is a view for explaining an image formed by each imaging lens when a concave lens field lens 3b is used.

FIG. 7 is a configuration diagram schematically showing an optical system used in an imaging device according to a second embodiment.

FIG. 8 is a diagram illustrating an example of a light shielding plate 35 according to the second embodiment.

[Explanation of symbols]

 1, 21, 31: imaging lens array 2, 22, 32: imaging element 3a, 3b: field lens 4, 34: low-pass filter 5: light shielding plate 23: rotation processing circuit 24: joining circuit 25: display device 26: recording apparatus

Claims (3)

[Claims] 1. An imaging device, comprising: a lens array having a plurality of imaging lens units disposed on an imaging surface side of the imaging device; wherein each imaging lens unit of the lens array has a different imaging range. An imaging device, characterized in that the imaging device is configured to have the same. 2. The image pickup apparatus according to claim 1, further comprising a field lens for causing a light beam to enter the lens array at a predetermined angle of view. 3. The imaging lens unit of the lens array is disposed on a virtual spherical surface, and the imaging element is disposed on a concentric virtual spherical surface having a smaller radius than the spherical surface, corresponding to each of the imaging lens units. The imaging device according to claim 1, wherein the imaging device is provided.