JP2003161879A - Imaging optical system and image photographing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging optical system, which can be reduced in size and thickness, with high productivity and an image photographing device incorporating it. <P>SOLUTION: Related to the imaging optical system, a plurality of imaging units provided with a beam reflecting means 3 which makes an object plane 1 and an image plane almost parallel to each other are disposed in second dimension in the inter-object optical path of an imaging optical means that meets so-called Scheimpflug condition in which a titled object plane 1, an image plane 4, and a main flat plane of an optical system 2 cross each other at the same straight line B. It comprises a unit image plane on which focusing is made by dividing, one to one, to the number identical with the imaging units, for synthesizing the images of divided unit image planes. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming optical system and an image capturing apparatus using the same, and particularly to a thin image forming optical system capable of wide angle of view, a digital camera and a digital video using the same. The present invention relates to an image capturing device such as a camera.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 10-107975 discloses that a diaphragm (pupil) is used in common, objective lenses are two-dimensionally arranged on a curved surface, and a corresponding number of photodetector units are arranged to output photoelectrically converted light. There is disclosed an image input device for synthesizing an image signal from. That is, it is a method of dividing an image, forming an image through a corresponding imaging optical system, and combining the entire image in post-processing. Here, a thin image input device of a compound eye system that imitates the compound eye of an insect that can improve resolution and brightness is shown.
However, according to the present invention, the photodetection section and the image introduction section have curved surfaces, so that there is a limit to reduction in thickness and size.

[0003]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming optical system which is further thinned, made compact, and has a wider angle, and an image taking apparatus using the image forming optical system. Is.

[0004]

According to a first aspect of the present invention, a so-called Scheimpflug in which an inclined object plane, an image plane and a main plane of an optical system intersect each other on the same straight line.
In the optical path between object images of the image forming optical means satisfying the condition of (2), a plurality of image forming units having light beam bending means for making the object plane and the image plane substantially parallel to each other are arranged two-dimensionally, and each of the same number as the image forming unit. 1
An image forming optical system comprising a unit object surface for dividing and forming an image corresponding to pair 1, and combining the divided images of the unit object surface. With such an imaging optical system,
It is thin and can be miniaturized.

According to a second aspect of the present invention, in the image forming optical system according to the first aspect, the respective unit image forming planes formed by the image forming units arranged in the two dimensions are the same. It is characterized in that they are on a common image plane, and the bending directions of the light rays by the light beam bending means are symmetrically arranged in directions that are away from each other when the object plane is viewed from the common image surface.

According to a third aspect of the present invention, in the image forming optical system according to the first aspect, the deviation angle formed by the light beam bending means is obtained by dividing the angle of view of the dividing direction of the image forming optical means by the number of divisions in that direction. It is characterized by being approximately equal to or slightly smaller than the value.

According to a fourth aspect of the present invention, in the image forming optical system according to the first aspect, the image forming optical means is a lens including one or a plurality of sheets, and the light beam bending means includes a prism including one or a plurality of sheets. The lens and the prism have the same arrangement interval and symmetrical inclination, and are arranged on a flat support substrate.

According to a fifth aspect of the present invention, in the image forming optical system according to the fourth aspect, at least one element selected from a lens and a prism of the image forming optical means is formed in a plate shape integrally with a supporting substrate. It is characterized in that it is formed by arranging.

According to a sixth aspect of the present invention, in the image forming optical system according to the fourth aspect, the prism and the lens are arranged in this order from the object plane, and the surface of the prism on the object plane side is the It is characterized by being parallel to the object plane.

According to a seventh aspect of the invention, in the image forming optical system according to the fourth aspect, the beam bending means includes a prism having a curved surface.

According to an eighth aspect of the present invention, there is provided the image forming optical system according to any one of the first to seventh aspects, wherein the unit image forming surface of the image forming optical system includes the unit formed by the image forming unit. The image pickup device is provided with image signal generating means for arranging light detecting means corresponding to image formation and synthesizing outputs of the respective light detecting means to generate an image signal.

According to a ninth aspect of the present invention, in the image photographing apparatus according to the eighth aspect, the unit image forming surface is provided with light detecting means of the number of image forming units or less, and one or each of the light detecting units. It is characterized by having an image signal generating means for synthesizing the outputs of the means to generate an image signal.

According to a tenth aspect of the present invention, in the image photographing apparatus according to the eighth or ninth aspect, one or more selected from the flat plate-shaped image forming optical means, the bending means, and the light detecting means are provided. On the optical path between the object images, by moving the respective flat plate-shaped means while maintaining the parallelism,
It is characterized by focusing.

According to an eleventh aspect of the present invention, in the image photographing apparatus according to any one of the eighth to tenth aspects, the image signal creating means reduces a shift in a joint portion of the combined image signals and a difference in characteristics. It is characterized by having a function of favorably reducing image distortion.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) In the following description, an image forming optical system comprises image forming optical means and light beam bending means. Further, one image forming unit is composed of one image forming optical means and one light beam bending means.
In the present embodiment, although the Scheimpflug condition is introduced and the beam bending means is added, the image is divided and the image is formed by the corresponding image forming optical means, but the object and the image are parallel to each other. An imaging optical system that can be positioned on a flat plane. With this configuration, it is thin, wide-angle,
It is possible to provide a compact imaging optical system.

When the object is tilted with respect to the optical axis (generally perpendicular to the optical axis), the image surface is tilted when tilted, and the Scheimpflug's law is established that intersects the lens (thin lens) surface in the same straight line. In a general optical system, there are an object-side principal plane and an image-side principal plane on the lens surface, and a distance occurs between the two planes, but this distance can be taken into consideration when designing. To do. In the present invention, in the optical path between object images of the imaging optical means satisfying the Scheimpflug condition,
A beam bending means is added to make the object plane and the image plane substantially parallel.

As shown in FIG. 1, the bending angle = deflection angle at this time is the angle formed between the object plane and the image plane (= α1 + α2). By using this as one image forming unit and arranging a plurality of two-dimensionally, it is possible to form the same number of divided images as the image forming unit, which is a drawback of various conventional inventions based on compound eyes, that is, image forming. The defect that the arrangement of the unit and the divided image is curved is solved, and the plane arrangement becomes possible.

Here, the image forming optical means can be a lens (system), a curved mirror (system), a hybrid optical system in which both are combined, a gradient index optical element, or the like. The light beam bending means means a mirror, a prism, a diffraction element, a Fresnel element, a hologram, or the like.

In FIG. 1, the object plane, the image-forming optical means, the light beam bending means, and the image plane are arranged in this order. However, the light-beam bending means and the image-forming optical means are replaced with each other. It is also possible to arrange a light beam bending means inside. With such a configuration, the angle of view of a set of imaging optical systems can be combined by arranging a plurality of angles, and wide-angle imaging or photographing can be performed similarly to the compound eye. Further, the flare light can be reduced by installing a light shielding plate in a range that does not block the imaging light (claim 1).

Further, the fact that the object plane and the image plane can be made parallel to each other enables the arrangement of image forming units to be arranged on the same plane for each component, and the division images can be formed on the same plane. That is,
When there are a plurality of lenses, they are arranged for each first lens, each second lens, or each beam bending means. Here, by symmetrically arranging the bending direction of the light beam by the light beam bending means in a direction away from each other when the object surface is viewed from the image plane, the area of the plane where the imaging optical means and the light beam bending means are arranged can be reduced. It is possible to provide an imaging optical system that is small, thin, and small. 2 is a cross-sectional view when two sets are arranged, and FIG. 3 is a projection view seen from the image plane when four sets are arranged. The bending direction of light rays by the ray bending means is the object plane viewed from the image plane. At times, it is shown that they are arranged symmetrically with respect to each other. From these, it can be seen that the image forming optical system can be integrated near the center line to realize downsizing. (Claim 2)

Further, when the divided images are formed on the same plane, it is not desirable that the information of the divided portions be lost. When a plurality of divided images are overlapped and formed, they can be connected by discarding them when creating an image signal, and when there are too many overlaps, the number of combined information decreases. It is necessary to consider the processing error and the placement error of the parts. Therefore, the deflection angle of the light beam bending means is almost equal to the value obtained by dividing the angle of view in the dividing direction of the imaging optical means by the number of divisions in that direction, or only slightly. It is desirable to be small. (Claim 3)

Furthermore, it is simple and effective to use one or a plurality of lenses as the image forming optical means, and it is also effective to use a prism as the light beam bending means. It is possible to position the imaging optical system by forming an opening for transmitting light rays on the flat plate and forming a shape portion for holding the optical component and arranging each component with the same arrangement interval and a symmetrical inclination. Further, according to this structure, the support substrate can serve both as the aperture stop and for removing stray light (claim 4).

Further, at least one of the lens and the prism can be formed integrally with the flat plate which is the supporting member. It can be processed by the molding method, and even when complicated and high precision is required when an aspherical surface is required for the lens, mass production is possible at low cost, and assembly can be simplified. (Claim 5)

Further, when the prism is formed integrally with the flat plate, the imaging optical system is arranged from the object side to the prism and the lens (system).
, And the prism surface on the object side is parallel to the object surface (=
Parallel to the image plane). One side of the mold can be made into a common flat surface, which is excellent in workability, and even if the mold is placed in a state where the user can easily touch it with a shooting device such as a camera, there is no unevenness, so it is possible to avoid dust from adhering and to clean it easily. Is also easy. Further, it is more effective to subject the relevant surface to a surface treatment for improving wear resistance. (Claim 6)

Furthermore, it is desirable to use a prism having a curved surface in the prism used. This is because the aberration can be reduced (claim 7).

Here, the drawings will be described. 1 and 2 are configuration diagrams of a first embodiment of the present invention. 3 and 4 are schematic views of the images formed by dividing the object plane into four and sixteen, respectively, as viewed from the image plane.

FIG. 1 shows that a beam bending means can be added to the image forming optical means satisfying the Scheimpflug condition to make the object plane and the image plane parallel to each other. The imaging optical means and the light beam bending means are arranged in this order from the object side. In the figure, the solid line is an optical path that does not have a light beam bending means and satisfies the Scheimpflug condition, and the broken line is an optical path in which the light beam bending means is inserted and the image plane is parallel to the object plane. Regarding the reference numerals, 1 is an object plane, 2 is an image forming optical means, 2'is a main plane of the image forming optical means, 4 is an image surface satisfying the Scheimpflug condition, 5 is an optical axis, 3 is a beam bending means, and Reference numeral 4'denotes an image plane which is parallel to the object plane by the beam bending means. Here, α1 is an angle formed by the object plane and the main surface of the image forming optical means, α2 is an angle formed by the main surface of the image forming optical means and the image plane, and θ is a half angle of view of the image forming optical means. Here, θ = (α1 + α2). Note that (α1 + α2) can be arbitrarily changed by changing the distance from the optical axis 5 to the line B of intersection of the object plane and the image plane.

In FIG. 2, the object side surface, the light beam bending means, the imaging optical means, and the image plane are arranged in this order, and the object plane and the object side optical path are indicated by broken lines only in the arrangement bent by the light beam bending means. . The alternate long and short dash line represents the center line as a perpendicular line from the center of the object, and two image forming optical systems are arranged symmetrically with respect to the center line. The object plane is continuously divided and imaged without any omission.
The object side surface of the prism is an example parallel to the object surface and forms a common coplanar surface. The eccentricity (tilt) of the lens is also kept symmetrical. Since the image forming optical means, the light beam bending means and the image surface formed by the divided image formation can be arranged in the vicinity of the center line, the image forming optical system and the image photographing device can be realized compactly. Regarding the reference numeral, 6 is a center line, and 1'is an object plane which is made parallel to the image plane by the beam bending means.

FIG. 3 is a view as seen from the image plane when an image is formed by dividing the object plane into four parts, and the bending directions of the rays by the ray bending means are such that they are distant from each other when the object plane is seen from the image plane. The figure shows how they are arranged symmetrically. The small circle is the starting point, and the direction of the arrow shows the bending direction of the light beam by the light beam bending means, and shows the direction of symmetry at the same time as the direction of inclination of the prism or the like.

FIG. 4 is a simplified diagram showing the commonality of the image forming optical means and the light beam bending means utilizing the symmetry when the object plane is divided into 16 parts. It is indicated that it can be used by changing.
Further, it is understood that the direction of bending by the beam bending means is preferably on the extension line connecting the center of each divided image and the center line, and it can be understood that four types can be used in the case of 16 divisions.

(Second Embodiment) In the image forming optical device according to the first embodiment of the present invention, the divided image for each image forming unit is an inverted image and cannot be connected as it is. An image signal can be created by arranging a photodetecting unit corresponding to an image forming unit on the image plane and synthesizing the outputs of the respective photodetecting units, so that an image capturing apparatus can be provided. Thin, small and wide-angle.
An area type CCD, C-MOS, or the like can be used as the light detecting means, and they can be arranged on the same plane. Since the outputs of a plurality of light detecting means are combined, an image signal having a large number of pixels can be obtained, and a high-density and high-definition image capturing device can be obtained. In addition to changing the CCD integration time, an ND filter can be used to control the proper exposure. Further, the flare light can be reduced by installing a light shielding plate in a range that does not block the imaging light (claim 8).

Further, the fact that the light detecting means can be arranged on the same plane enables the number of light detecting means to be smaller than the number of image forming units. The minimum number of light detecting means is one. An image signal is obtained by synthesizing the photoelectrically converted signals at the addresses corresponding to the divided images. Although there is little or no effect of increasing the number of pixels by combining, it is possible to obtain a more compact and low-cost image capturing device. (Claim 9)

Further, all or a part of the image forming optical means,
By moving one or both of the image forming optical means and the light detecting means in parallel to the object plane, a function capable of focusing can be provided. Focusing is extremely difficult with the conventional compound eye method in which the image forming optical means and the light detecting means are arranged on a curved surface, which is a great advantage. Compared to the previous method, which is limited to the depth, the shooting range can be greatly expanded. Such a function can be performed by a conventional method (claim 10).

Further, it is known that trapezoidal distortion (Keystone Distortion) occurs under the Scheimpflug image formation condition. There is a possibility that the beam bending means can reduce the trapezoidal distortion, but by electrically correcting a part of the distortion of the image shape of the imaging optical system, the burden on the imaging optical system is reduced and high performance is achieved. You can get a statue. It is possible to obtain an image capturing device capable of reproducing a high-quality image by not only performing the image inversion for each divided image but also having a function of reducing the difference in the shape of the joint portion, the brightness, and the hue. . (Claim 11)

[0035]

According to the image forming optical system of the present invention, the angle of view of a set of image forming optical systems can be combined by arranging a plurality of them, and in addition to the compound eye, wide angle image forming or photographing can be performed. Further, it is possible to further reduce the size and thickness by using the beam bending means to make the image forming surface a common plane. In addition, the image forming optical means and the ray bending means,
By making a plurality of flat plate-shaped arrangements, each of these means can be formed as a flat plate unit, so that productivity such as mounting, ease of molding, and manufacturing accuracy can be improved. It contributes to cost reduction. Further, such a configuration can also contribute to downsizing and thinning.

Since the image photographing apparatus of the present invention incorporates the image forming optical system having the above effects, the image photographing apparatus itself can be made smaller and thinner, and the divided image is corrected. The function makes it possible to capture a clear image in which trapezoidal distortion is corrected in an optical system that satisfies the Scheimpflug condition.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of the first embodiment.

FIG. 3 is a schematic view of an image formed by dividing an object plane into four and viewed from the image plane.

FIG. 4 is a schematic diagram of an image formed by dividing an object plane into 16 parts and viewed from the image plane.

[Explanation of symbols]

1 ... Object plane 2 ... Imaging optical means 2 '... Main plane of imaging optical means 3 ... Beam bending means 4 ... Image plane 4' ... by ray bending means satisfying Scheimpflug condition Image plane 5 that is parallel to the object plane .... Optical axis.

Claims (11)

[Claims] 1. A so-called Scheimpflug (Sch) in which an inclined object plane, an image plane and a principal plane of an optical system intersect on the same straight line
In the optical path between object images of the image forming optical means satisfying the condition of (eimpflug), a plurality of image forming units having light beam bending means for making the object plane and the image plane substantially parallel are arranged two-dimensionally, and the same number as the image forming units is provided. An image forming optical system comprising: unit image planes that are divided and image-formed in a one-to-one correspondence with each other, and combine the divided images of the unit image planes. 2. The respective unit imaging planes imaged by the respective two-dimensionally arranged imaging units,
It is on the same common image forming plane, and the bending directions of the light rays by the light ray bending means are symmetrically arranged so that they are distant from each other when the object plane is viewed from the common image forming plane. The imaging optical system according to claim 1. 3. The deflection angle formed by the beam bending means is substantially equal to or slightly smaller than a value obtained by dividing the angle of view of the imaging optical system in the division direction by the number of divisions in that direction. The image forming optical system according to claim 1. 4. The image forming optical means is a lens composed of one or a plurality of lenses, and the light beam bending means is a prism composed of one or a plurality of lenses. The lenses and the prisms have the same arrangement interval. The image forming optical system according to claim 1, wherein the image forming optical systems have symmetrical inclinations and are arranged on a flat support substrate. 5. The image forming unit according to claim 4, wherein each of at least one element selected from a lens and a prism is integrally arranged in a flat plate shape. Image optics. 6. The prism and the lens are arranged in this order from the object, and the surface of the prism on the object plane side is parallel to the object plane. Imaging optics. 7. The image forming optical system according to claim 4, wherein the light beam bending means includes a prism having a curved surface. 8. An image forming optical system according to claim 1, wherein the unit image forming surface of the image forming optical system corresponds to the unit image forming by the image forming unit. An image pickup apparatus, comprising: an image signal generating unit that is provided with each of the light detecting units and that synthesizes outputs of the respective light detecting units to generate an image signal. 9. An image signal generating means for arranging on the unit image-forming surface, light detecting means equal to or smaller than the number of image forming units and synthesizing an output of one or each of the light detecting means to generate an image signal. The image capturing apparatus according to claim 8, further comprising: 10. One selected from the flat plate-shaped image forming optical means, the light beam bending means, and the light detecting means.
The image photographing apparatus according to claim 8 or 9, wherein the above-mentioned means is moved on the optical path between the object images while maintaining the parallelism of the respective flat plate-shaped means to focus. 11. The image signal generating means has a function of reducing a shift or a difference in characteristics of a joint portion of the combined image signals, and satisfactorily reducing image distortion. The image capturing device according to 1 of 10.