JP2001211464A - Image pickup device and stereoscopic image pickup device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image pickup device capable of easily obtaining image information of high optical performance by using a light quantity control means having a polarizing plate and an image pickup element periodically fetching an image, and to provide a stereoscopic image pickup device using the image pickup device. SOLUTION: In this image pickup device for forming the image information on the surface of the image pickup element periodically fetching the image through a low-pass filter for dividing incident light into a plurality of light rays by double refraction by using the light quantity control means having the polarizing place and a photographic optical system, the light quantity control means and the low-pass filter are arranged so that the polarization axis of the polarizing plate of the light quantity control means does not match the light division direction of the low-pass filter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device and a stereoscopic image pickup device using the same, and more particularly, to one image pickup device (CC).
D) When image information is obtained by using shutter means (light amount control means) or an image having parallax between left and right eyes (parallax image)
Are alternately guided in time series to obtain a stereoscopic image.

[0002]

2. Description of the Related Art In order to observe a stereoscopic image, a plurality of parallax images are required. 2. Description of the Related Art Conventionally, various imaging apparatuses and imaging optical systems for capturing a stereoscopic image for obtaining a plurality of parallax images have been proposed.

[0003] Among them, a stereoscopic image photographing apparatus that uses a liquid crystal shutter to alternately guide image information having left and right parallax to the same area of one image sensor in a time series is disclosed in, for example, Japanese Patent Application Laid-Open No. 6-327036. It has been proposed in Japanese Patent Application Laid-Open No. 8-251624.

In Japanese Patent Application Laid-Open No. Hei 6-327036, a left and right reflecting mirror, a liquid crystal shutter, and a photographing lens are provided, and the liquid crystal shutter is arranged near the entrance pupil of the photographing lens on the subject side of the photographing lens. By doing so, an image having left and right parallax can be alternately input to one image sensor.

In FIG. 1 of Japanese Patent Application Laid-Open No. 8-251624, a stereoscopic image photographing optical system includes two mirrors having left and right variable reflection angles, two mirrors having left and right, two sets of right and left polarization filters, and two sets of left and right mirrors. It consists of a lens system and one image sensor. Then, the amount of light based on the left and right parallax images is changed by rotating the polarization filter, and the light that has passed through the optical path for the left and right parallax images is alternately guided to the image sensor to obtain a parallax image.

[0006]

In a conventional stereoscopic image photographing apparatus using a CCD as an image pickup means, there is no description about a structure showing a relationship between a liquid crystal shutter and a low-pass filter. For example, if the polarization axis of the polarizing plate constituting the liquid crystal shutter matches the light beam separating direction of the low-pass filter, the low-pass effect decreases, and it becomes difficult to obtain image information with high optical performance.

Conventionally, it has not been determined how to cope with such a situation. In an optical system for capturing a stereoscopic image, it is important to obtain parallax images for the left and right eyes with high optical performance in order to properly observe the stereoscopic image.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photographing apparatus capable of easily obtaining image information having high optical performance by appropriately setting a light amount control means having a polarizing plate and an optical path separating direction by a low-pass filter.

Further, according to the present invention, a parallax image of the right and left eyes is imaged in a time series using a light quantity control means having a polarizing plate such as a liquid crystal shutter by a photographing apparatus using an imaging means such as a CCD and a low-pass filter. When a plurality of parallax images are obtained by guiding the light to the means, a plurality of parallax images with good optical performance can be easily obtained by appropriately setting the polarization axis of the polarizing plate and the light beam separation direction by the low-pass filter. It is intended to provide an imaging device.

[0010]

According to a first aspect of the present invention, there is provided an image pickup apparatus which separates an incident light beam into a plurality of light beams by birefringence by using light amount control means having a polarizing plate and a photographing optical system. In an imaging apparatus formed on an imaging element surface which periodically captures an image via a low-pass filter, the light quantity control means and the low-pass filter are arranged such that a polarization axis of a deflecting plate of the light quantity control means is in a light separating direction of the low-pass filter. It is characterized in that it is arranged so as not to match with.

According to a second aspect of the present invention, there is provided an image pickup apparatus, comprising: a light quantity control unit having a polarizing plate; and a low-pass filter that separates an incident light beam into a plurality of light beams by birefringence using an imaging optical system. In an imaging apparatus formed on an image sensor surface for capturing an image, the light amount control means and the low-pass filter are formed by setting the angle between the polarization axis of the polarizing plate of the light amount control means and the light beam separating direction of the low-pass filter to θ. In this case, the arrangement is such that 30 ° <θ <60 ° is satisfied.

According to a third aspect of the present invention, in the first or second aspect, an imaging means A including the light amount control means and the imaging optical system and an imaging means B including the low-pass filter and the imaging element are provided. It is characterized by being configured to be separable and connectable.

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, at least one or both of the light quantity control means and the low-pass filter have positioning means for performing relative positioning of both. Features.

According to a fifth aspect of the present invention, in the third aspect of the present invention, a polarization axis of the polarizing plate of the light amount control means is provided on a division portion capable of dividing and combining the imaging means A and the imaging means B,
It is characterized in that a positioning means for adjusting an angle between the low-pass filter and the light beam separating direction is provided.

According to a third aspect of the present invention, there is provided a three-dimensional imaging apparatus, wherein two light quantity control means having polarizing plates are provided for the left and right eyes, and a light beam from image information is transmitted through the two light quantity control means for the left and right eyes. An imaging element surface that periodically captures an image through a low-pass filter that separates incident light into a plurality of light beams by birefringence of image information having two parallaxes for the right and left eyes using a combining optical unit and a photographing optical system. In the above three-dimensional imaging apparatus, the two light quantity control means and the low-pass filter are controlled by controlling the light quantity control means so that the polarization axes of the polarizing plates of the two light quantity control means are the low-pass filter. Are arranged so as not to coincide with the light ray separation direction.

According to a seventh aspect of the present invention, there is provided a three-dimensional image pickup apparatus, wherein two light quantity control means having polarizing plates are provided for the left and right eyes, and a light beam from image information via the two light quantity control means for the left and right eyes is synthesized. An imaging element surface that periodically captures an image through a low-pass filter that separates incident light into a plurality of light beams by birefringence of image information having two parallaxes for the right and left eyes using a combining optical unit and a photographing optical system. In the above three-dimensional imaging apparatus, the two light quantity control means and the low-pass filter are controlled by controlling the light quantity control means, and the two light quantity control means and the low-pass filter are provided with the polarization axes of the polarizing plates of the two light quantity control means. When the angle between the filter and the light separating direction is θ, the filter is arranged so as to satisfy 30 ° <θ <60 °.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, an imaging means A including the two light quantity control means and the imaging optical system, and an imaging means B including the low-pass filter and the imaging element. Is characterized by being configured to be separable and connectable.

According to a ninth aspect of the present invention, in the invention of the sixth, seventh or eighth aspect, at least one of the two light quantity control means or the low-pass filter has a positioning means for performing relative positioning between the two. Features.

According to a tenth aspect of the present invention, in the eighth aspect of the present invention, the polarization axes of the polarizing plates of the two light quantity control means are provided at a division portion where the imaging means A and the imaging means B can be divided and combined. It is characterized in that a positioning means for adjusting an angle formed by the light separating direction of the low-pass filter is provided.

[0020]

FIG. 1 is an optical sectional view of a three-dimensional photographing apparatus using a three-dimensional photographing optical system according to a first embodiment of the present invention. The stereoscopic imaging optical system (imaging optical system) shown in FIG. 1 includes a zoom lens and obtains two parallax images in time series.

The photographing optical system shown in FIG. 1 has left and right optical axes AXL, A which are arranged substantially in parallel at intervals substantially equal to the width of the human eye.
Two right and left reflection mirrors ML and MR for deflecting the XR inward respectively, two left and right first lens groups 1GL and 1GR having the same configuration of negative refractive power, and two right and left as light quantity control means including a polarizing plate. A triangular prism (reflection coating (high reflection film) applied to the surfaces HL, HR) for overlapping the liquid crystal shutters SL, SR and the left and right optical axes AXL, AXR disposed at or near the aperture position of the photographing optical system ( A combining optical element) P, a stop SP for adjusting the amount of light, a second lens group 2G for focusing alone moving on the optical axis AX,
A third lens group 3G having a positive refractive power as a whole, which is movable on the optical axis from the image side to the object side during zooming from the wide-angle end to the telephoto end.
And a fourth lens group 4G having a positive refractive power as a whole that is movable on the optical axis in order to correct an image plane position accompanying zooming from the wide-angle end to the telephoto end and to correct variations in back focus. And a fifth lens group 5G having a positive refracting power, a sixth lens 6G having a negative refracting power, and a quartz plate which are movable as a whole on the optical axis in order to correct variations in back focus. Optical low-pass filter LPF for separating the optical path by means of an image pickup means (CC)
D).

In this embodiment, the sixth lens group 6
Color separation means may be provided between G and the imaging means CCD to separate incident light into a plurality (three) of color lights. At this time, a photographing means is provided for each color light.

In this embodiment, the second lens group 2G is moved in the direction of the optical axis to correct (focus) the shift of the image plane position due to the change in the object distance, and to change the magnification from the wide-angle end to the telephoto end. The third lens group 3G and the fourth lens group 4G are moved from the image sensor CCD to the subject side to perform magnification and correction of the image plane position accompanying the magnification.

Note that the first lens groups 1GR and 1GL constitute a front lens group, and the second lens group 2G to the sixth lens group 6
G constitutes a rear lens unit. The front lens group and the rear lens group constitute a zoom lens.

By alternately opening and closing the two left and right liquid crystal shutters (light quantity control means) SL and SR, image information having left and right parallax is alternately guided in time series on the image sensor CCD.

The left and right liquid crystal shutters SL (SR) are each composed of a polarizing plate H1, a cover glass (not shown), a liquid crystal layer (liquid crystal portion) LCD, a cover glass (not shown), and a polarizing plate H2 from the object side. . A transparent electrode is provided on the surface facing the liquid crystal layer LCD.

The two light quantity control means and the low-pass filter are arranged so that the polarization axes of the polarizing plates of the two light quantity control means do not coincide with the light beam separating directions of the low-pass filter. Specifically, the angle θ formed between the polarization axes of the polarizing plates of the two light quantity control means and the light beam separating direction of the low-pass filter.
Are arranged using the positioning means so as to be within the range of 30 ° <θ <60 °.

In this embodiment, the present invention may be used as an image pickup device for forming single image information without parallax on the image pickup device CCD. In this case, one of the left and right eye members (for example, MR, 1GR, SR) may be used, or only one element may be left and the other element (in this case, the synthetic optical means P) may be used. You may delete and comprise. or,
At this time, the light amount control means may be used as a simple shutter.

In addition, in this embodiment, the image pickup means LA including each element from the reflection mirror (MR, ML) to the sixth lens group 6G, and the image pickup means LB including the low-pass filter (LPF) and the image pickup device CCD. It may be configured as an independent imaging unit that can be separated and combined, and both may be separated and joined as needed.

FIG. 2 shows the liquid crystal shutters SL and S in FIG.
FIG. 4 is an explanatory diagram showing an arrangement relationship among R, a low-pass filter LPF, and a CCD.

In FIG. 2, the direction of polarization of the polarization axis of the liquid crystal layer (liquid crystal portion) of the liquid crystal shutter and the low pass filter L are shown.
The presence or absence of a low-pass effect based on the relative angle θ between the PF and the light beam separation direction is shown. In the present embodiment, FIG.
As shown in (A), the relative angle θ between the light separating direction of the low-pass filter LPF and the LCDR and LCDL is 45 °, which satisfies the condition of 30 ° <θ <60 °. Effectively obtained. As shown in FIG. 2B, when θ = 0, light beam separation by the low-pass filter LPF is inhibited, and the low-pass effect is reduced. If the light separating direction of the low-pass filter LPF is one, θ = 90 ° is most preferable, and a low-pass effect of 100% can be maintained. In practice, the low-pass filter LPF is generally considered to be separated in two directions, vertical and horizontal.
The design value is around = 45 °. The graph of FIG. 2 (C) shows that the low-pass effect changes with COS θ% in the case of horizontal separation, and FIG. 2 (D) shows that the vertical separation changes with SIN θ%. The angle θ is limited to the range of 30 ° to 60 ° in order to keep the effect in each case.

FIG. 3 is a schematic diagram showing mechanical means for fixing the liquid crystal shutter unit SR (SL) of the present embodiment. The liquid crystal part LCD sandwiched between the polarizing plates H1 and H2 and the LCD frame U integrally including these are provided with positioning pins Ua and Ub as two positioning means on the lens frame B.
B, BT are fitted into the openings of the rigid portions BBb, BTb provided on the BT. Thereby, the light beam separating directions of the liquid crystal shutter and the low-pass filter are set at a predetermined angle. The rotation of the liquid crystal shutter about the optical axis is restricted by the positioning pins Ua and Ub. Rigid body B
The liquid crystal shutter unit is abutted and fixed in the optical axis direction by Bb and the elastic portion BTa. Fixing means (BBb, B
Ta) is applied to the left and right liquid crystal shutter units, and the polarization direction of each liquid crystal shutter unit is set to be 45 ° with respect to the light beam separation angle of the crystal low-pass filter. However, the polarization direction of the polarizing plate must be LC
The mounting angle is determined with respect to the positioning pins Ua and Ub of the D frame U, and the unit is assembled.

In this embodiment, the positioning means for adjusting the polarization axis of the polarizing plate of the liquid crystal shutter and the light beam separating direction of the low-pass filter may be provided in at least one of the liquid crystal shutter and the low-pass filter. Further, when the image pickup means LA and the image pickup means LB are configured by an interchangeable lens system so as to be separable and connectable, the positioning means may be provided in a split part that can be separated and connected, for example, a mount part.

FIG. 4 is an explanatory view of another embodiment of the mechanical means for fixing the liquid crystal shutter unit of the present embodiment. The outer shape of the LCD frame U is a D-cut shape, the opposing lens frame CC is also a fitting shape, and the rotation of the LCD unit in the lens frame CC is restricted.
In order to regulate in the optical axis direction at S, the lens frame screw receiving part CC
The holding plate OS is fixed to c by a screw RO. However, the polarizing direction of the polarizing plate is set in a unit with the mounting angle determined with respect to the D-cut surface of the LCD frame U in advance.

[0035]

According to the present invention, it is possible to achieve a photographing apparatus in which image information with high optical performance can be easily obtained by appropriately setting a light amount control means having a polarizing plate and an optical path separating direction by a low-pass filter. Can be.

According to the present invention, the parallax images of the left and right eyes can be time-sequentially converted by a photographing apparatus using an image pickup means such as a CCD and a low-pass filter by using a light amount control means having a polarizing plate such as a liquid crystal shutter. When a plurality of parallax images are obtained by guiding the light to one imaging unit, a plurality of parallax images having good optical performance can be easily obtained by appropriately setting the polarization axis of the polarizing plate and the light beam separation direction by the low-pass filter. The resulting stereoscopic imaging device can be achieved.

In addition, according to the present invention, by providing the rotation restricting means of the liquid crystal shutter in a part of the lens barrel, the low-pass effect of the crystal low-pass filter can be maintained with high efficiency, and the image quality can be prevented from deteriorating. Also, in a stereoscopic imaging device in which liquid crystal shutters are provided independently for left and right, a low-pass effect can be maintained with high efficiency by establishing a relative relationship in the same manner.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an optical arrangement according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the presence or absence of an effect due to the polarization direction of the liquid crystal shutter unit according to the present invention and the relative angle of the crystal low-pass filter.

FIG. 3 is an explanatory view of a mechanical fixing means of the liquid crystal shutter unit according to the present invention.

FIG. 4 is an explanatory view of other mechanical fixing means of the liquid crystal shutter unit according to the present invention.

[Explanation of symbols]

 MR ・ ・ Right mirror ML ・ ・ Left mirror H1 ・ ・ Polarizer 1 H2 ・ ・ Polarizer 2 H3 ・ ・ Polarizer 3 H4 ・ ・ Polarizer 4 LCDR ・ ・ Right liquid crystal shutter LCDL ・ ・ Left liquid crystal shutter P ・ ・ Triangle Prism SP ... Stop 1GR 1st lens group 2GR 2nd lens group 3GR 3rd lens group 4GR 4th lens group 5GR 5th lens group 6GR 6th lens group LPF Quartz low-pass filter CCD ... Image sensor B ... Mirror frame 1 U ... LCD frame CC ... Mirror frame 2 OS ... Holding plate RO ... Screw

Claims (10)

[Claims] 1. An imaging element surface that periodically captures an image via a low-pass filter that separates incident light into a plurality of light rays by birefringence of image information using a light amount control unit having a polarizing plate and an imaging optical system. In the imaging device formed above, the light quantity control means and the low-pass filter are arranged such that the polarization axis of the polarizing plate of the light quantity control means does not coincide with the light beam separation direction of the low-pass filter. Imaging device. 2. An image sensor surface that periodically captures an image through a low-pass filter that separates incident light into a plurality of light beams by birefringence of image information using a light amount control unit having a polarizing plate and a photographing optical system. In the imaging device formed above, the light amount control means and the low-pass filter are arranged such that when an angle between the polarization axis of the polarizing plate of the light amount control means and the light beam separating direction of the low-pass filter is θ, 30 ° <θ <60 °. An imaging apparatus characterized by being arranged so as to satisfy <60 °. 3. An imaging unit A including the light amount control unit and the imaging optical system, and an imaging unit B including the low-pass filter and the imaging element are configured to be separable and connectable. The imaging device according to claim 1, wherein 4. The image pickup apparatus according to claim 1, wherein at least one or both of the light amount control means and the low-pass filter has a positioning means for performing relative positioning between the two. 5. A position for adjusting an angle between a polarization axis of a polarizing plate of the light amount control means and a light beam separating direction of the low-pass filter in a division part capable of dividing and combining the imaging means A and the imaging means B. 4. The imaging apparatus according to claim 3, further comprising means. 6. Light quantity control means having polarizing plates for left and right eyes, combining optical means for combining light beams from image information via the two light quantity control means for right and left eyes, and a photographing optical system. And controlling the light amount control means on an imaging element surface which periodically captures an image through a low-pass filter that separates incident light into a plurality of light beams by birefringence of image information having two parallaxes for the left and right eyes. In the three-dimensional imaging device which is formed alternately in time series, the two light quantity control means and the low-pass filter are arranged such that the polarization axes of the polarizing plates of the two light quantity control means do not coincide with the light beam separation direction of the low-pass filter. A stereoscopic imaging device, which is arranged. 7. Light quantity control means having polarizing plates for the left and right eyes, combining optical means for combining light beams from image information via the two light quantity control means for the left and right eyes, and a photographing optical system. And controlling the light amount control means on an imaging element surface which periodically captures an image through a low-pass filter that separates incident light into a plurality of light beams by birefringence of image information having two parallaxes for the left and right eyes. In the three-dimensional imaging device which is formed alternately in time series, the two light quantity control means and the low-pass filter are formed by an angle between a polarization axis of a polarizing plate of the two light quantity control means and a light beam separation direction of the low-pass filter. The stereoscopic imaging apparatus is arranged so that 30 ° <θ <60 ° is satisfied when θ is θ. 8. An imaging unit A including the two light quantity control units and the imaging optical system, and an imaging unit B including the low-pass filter and the imaging element are configured to be separable and connectable. The three-dimensional imaging device according to claim 6 or 7, wherein 9. The stereoscopic imaging apparatus according to claim 6, wherein at least one of the two light quantity control means or the low-pass filter has a positioning means for performing relative positioning between the two. 10. An angle between a polarization axis of a polarizing plate of the two light quantity control means and a light beam separating direction of the low-pass filter is adjusted in a division part capable of dividing and combining the imaging means A and the imaging means B. 9. The three-dimensional imaging apparatus according to claim 8, further comprising a positioning means for performing the positioning.