JP3397396B2 - Imaging device - Google Patents

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, and more particularly to a high resolution image information easily obtained by using a plurality of image pickup elements having a limited number of pixels without increasing the number of pixels of the image pickup element. The present invention relates to an image pickup apparatus suitable for, for example, a small video camera or a still video camera.

[0002]

2. Description of the Related Art In recent years, solid-state area sensors (image sensors in which pixels are two-dimensionally arranged) as image pickup devices used in image pickup devices such as small video cameras and still video cameras have high pixel counts and low prices. It can be made smaller and smaller, and is used in many imaging devices.

The number of pixels of an image pickup device which is currently put into practical use is about 400,000, which has a resolution equivalent to that of a television of the current standard such as NTSC. However, for example, when the input image is displayed on a large screen image, hard copy or computer graphic,
The roughness of the pixels becomes noticeable, and it is difficult to output as a high-definition image.

Recently, a solid-state area sensor of 2 million pixels for HDTV is being developed. However,
Even with this number of pixels, the resolution is not sufficient to be used as an input for super-large screen display. The number of pixels of the current area sensor is not always sufficient to obtain an image with higher resolution (high resolution).

Conventionally, as a method of obtaining a high-definition image using an image pickup device, there is a method of obtaining a high-resolution image by increasing the pixel density of the image pickup device and increasing the number of pixels.

Generally, when the pixel area is reduced in order to increase the pixel density, the output signal becomes small and the S / N ratio deteriorates. Considering this decrease in the S / N ratio, the number of pixels of 2 million is almost the limit, and it is very difficult to further increase the number of pixels and improve the resolution under the present circumstances.

Therefore, various methods for obtaining a high-definition image without increasing the number of pixels have been proposed. For example, Japanese Patent Publication No. 50-13052 and Japanese Patent Publication No. 59-189.
No. 09, Japanese Patent Publication No. 59-43035, and the like propose a method using pixel shifting.

In this pixel shift method, an optical element for splitting a light beam based on a subject image on the image plane side of the image pickup optical system,
For example, by disposing a dichroic prism, a half mirror, or the like, and imaging the light beams divided by the optical element with a plurality of solid-state area sensors arranged by shifting the position by a half pitch of pixels or less, a high resolution image can be obtained. I'm getting an image.

Further, in Japanese Patent Laid-Open No. 4-286480, one or more optical path splitting means is arranged behind the imaging lens, the optical path splitting means divides the subject image into a plurality of divided subject images. An image is formed on each of a plurality of solid-state area sensor surfaces arranged at image forming plane positions, and the entire subject image is taken by interpolating areas that cannot be picked up by sensors at other image forming positions. Has obtained a high resolution image.

Further, in Japanese Patent Laid-Open No. 63-193678, a wedge-shaped deflecting member is arranged in the optical path of the photographing optical system, and the movement of the image caused by the rotation of the deflecting member is periodically picked up by an image pickup element. Therefore, image information of more than the number of pixels is obtained.

Further, in Japanese Patent Application Laid-Open No. 60-250789, a subject image formed by a photographing optical system is separated into a plurality of images by a secondary imaging optical system, and the separated plurality of images are respectively separated by a plurality of image pickup devices. A high-resolution image is obtained by forming an image on a surface and synthesizing and outputting image pickup signals from the plurality of image pickup elements.

[0012]

The method using pixel shifting as a method for obtaining a high-definition image has a problem that the resolution does not increase so much for the number of elements (pixels).

In the method proposed in Japanese Patent Laid-Open No. 4-286480, a high resolution image can be obtained by increasing the number of divisions of the optical path innumerably. For that purpose, the back focus of the taking lens is used. Had to be extremely long, and there was a problem that the size of the entire apparatus was increased. Therefore, in practice, the two-plate type or the three-plate type is the limit even if a 3P prism or the like is used.

Further, the method proposed in Japanese Patent Laid-Open No. 63-193678 is not suitable for a moving image because an image of one frame is combined by taking a plurality of times, and even if it is a still image, it is an output image. There was a problem that it took too much time to obtain.

Further, in the method proposed in Japanese Patent Laid-Open No. 60-250789, a light beam splitting mirror as a light beam splitting means is arranged so as to be slightly shifted from the primary image forming plane so that a boundary portion of an image is formed. Although pixel loss is prevented, there is a problem in that the structure is very difficult due to problems such as the thickness of the light beam separation mirror and the pupil of the off-axis light beam. In addition, the number of pixels increases at most about 2 to 3 times, which makes it difficult to obtain a high-resolution image.

According to the present invention, a plurality of image pickup devices having a limited number of pixels are used to appropriately set the arrangement of each image pickup device and each optical element that constitutes an image pickup system when a subject image is formed on each image pickup device. Accordingly, it is an object of the present invention to provide an image pickup device in which high-definition image information can be easily obtained.

[0017]

[Means for Solving the Problems]

(1-a) In the image pickup apparatus of the present invention, a subject image is formed on a planned image forming surface by the first optical system, and the object image is arranged on the optical axis of the first optical system and near the planned image forming surface. And the second optical system
All the subject images formed on the planned image forming plane by the third optical system arranged on the optical axis of the first optical system and behind the second optical system are used by the first image pickup means. The image of the object formed on the planned image forming plane is re-imaged and has an optical axis outside the optical axis of the first optical system and is arranged behind the second optical system. An image pickup device which reimages a part of the image on the second image pickup means and obtains high-definition image information by using image information obtained by the first image pickup means and the second image pickup means. The second optical system is characterized by having an optical member in which the directivity of the light beam differs depending on the incident position.

In particular, the fourth optical system has a plurality of lens systems, the second image pickup means has a plurality of image pickup elements corresponding to the plurality of lens systems, and Four
The plurality of lens systems of the optical system of (1) form the object images of the respective areas when the object image formed by the first optical system is divided into a plurality of areas on the corresponding image pickup device surfaces. Obtaining one image information by using image information obtained from a plurality of image pickup devices constituting the second image pickup means and image information obtained from the first image pickup means,
The second optical system is characterized in that it has a first optical member in which the directivity of the light beam differs depending on the incident position and a second optical member having a positive refractive power.

(1-b) In the image pickup device of the present invention, a subject image is formed on a predetermined image forming surface by the first optical system, and the first optical system and the optical axis arranged near the predetermined image forming surface. A second optical system having the same structure, and a third optical system which is arranged behind the second optical system and whose optical axis coincides with that of the first optical system. All the formed subject images are formed on the surface of the first image pickup means, image information about all the subject images is obtained from the first image pickup means, and the plurality of divided object images formed on the planned image formation plane are divided. Corresponds to the plurality of lens systems by a fourth optical system having a plurality of lens systems having an optical axis different from the optical axis of the first optical system and arranged behind the second optical system. An image from each of the plurality of image pickup devices is formed on each of the plurality of image pickup device surfaces of the second image pickup device having the plurality of image pickup devices. The second optical system is an image pickup device that obtains image information about all the subject images by synthesizing the information, and is characterized in that the second optical system has an optical member in which the directivity of the light flux differs depending on the incident position. .

In particular, the second optical system is characterized by having a first optical member in which the directivity of the light beam differs depending on the incident position and a second optical member having a positive refractive power.

[0021]

FIG. 1 is a sectional view of the essential parts of an optical system according to the first embodiment of the present invention, and FIG. 2 is a perspective view of the essential parts of the first embodiment of the present invention.

In the figure, reference numeral 1 denotes a first optical system, which forms a subject image on a primary image forming surface (planned image forming surface) 21.

Reference numeral 2 is a second optical system, and the first optical system 1
On the optical axis of the first imaging plane 21 and the second deflecting element 22 having a positive refracting power as the first optical member in which the directivity of the light beam differs depending on the incident position. It is composed of a field lens 23 as an optical member, and collects the light flux from the subject image formed on the primary image forming surface 21 and guides it to the subsequent lens system.

In this embodiment, as will be described later, the pupil position of the third optical system 3 and the fourth optical system 4 are controlled by the first optical member 22.
, And the pupil position of the first optical system is conjugate with the pupil 3a of the third optical system by the second optical member 23. Pupils 4A1, 4B1, 4 of the plurality of lens systems 4A, 4B, 4C, 4D of the system 4
C1 and 4D1 are formed in the vicinity of the divided pupil area of the first optical system 1.

Reference numeral 3 is a third optical system, and the first optical system 1
It is arranged on the optical axis of, and behind the second optical system 2 (on the image plane side). That is, the optical axis of the third optical system 3, the optical axis of the first optical system 1, and the optical axis of the second optical system 2 coincide with each other.

Reference numeral 31 denotes a first image pickup means (main image pickup means), which is disposed on the image forming plane behind the third optical system 3 and is composed of, for example, a solid area sensor.

The entire area of the subject image formed on the primary imaging plane 21 by the first optical system 1 is recombined on the surface of the first image pickup means 31 by the second optical system 2 and the third optical system 3. I'm making you image.

Reference numeral 4 denotes a fourth optical system, which has four lens systems: a 41st lens system 4A, a 42nd lens system 4B, a 43rd lens system 4C, and a 44th lens system 4D.

The four lens systems 4A, 4B, 4C and 4D have an optical axis outside the optical axis of the first optical system 1 and the second optical system 2
It is located behind.

Reference numeral 41 denotes a second image pickup means (sub-image pickup means), which is, for example, four image pickup elements 4 each including a solid-state area sensor.
1A, 41B, 41C, 41D, which are arranged on the image planes of the four lens systems 4A, 4B, 4C, 4D, respectively.

Four lens systems (4A, 4) of the fourth optical system
B, 4C, 4D) divides the subject image on the primary imaging surface 21 formed by the first optical system 1 into a plurality of regions, and the subject images in the respective regions are respectively associated with the respective image pickup devices 41A, 41B, 41
The image is re-formed on the C and 41D planes.

In this embodiment, the second optical member 23 of the second optical system 2 has a pupil 1a of the first optical system 1 and a pupil 3a of the third optical system 3 as shown by an optical path 32 of a solid line in the figure. And and are substantially conjugate to each other. Further, as shown by an optical path 42 indicated by a broken line in the figure, a plurality of lens systems 4 constituting the fourth optical system 4 are formed.
A, 4B, 4C, 4D pupils 4A1, 4B1, 4C1, 4
The images D1 are formed near the divided pupil regions of the first optical system 1, respectively.

Further, the first optical member 22 of the second optical system 2
Thus, the pupil position of the third optical system 3 and the pupil positions of the four lens systems 4A, 4B, 4C, and 4D forming the fourth optical system 4 are appropriately set.

In this embodiment, as shown in FIG.
The subject image is formed on the primary image forming surface 21 by the optical system 1, and the subject image is formed on the surface of the first image pickup means 31 by the third optical system 3 through the second optical system 2. The entire area of is imaged. Further, the four lens systems 4A, 4B, 4C, and 4D of the fourth optical system 4 divide the subject image formed on the primary imaging surface 21 into four regions, and divide the subject image in each region into the second region. The four image pickup devices 41A, 41B, 41C and 41D constituting the image pickup means 41 are imaged respectively.

When a high resolution image is required in the present embodiment, the image pickup elements 41A and 41B corresponding to the subject image by the fourth optical system 4 including four lens systems 4A, 4B, 4C and 4D, respectively. , 41C, 41D are divided into images to form images, and the four image pickup devices 41A, 41B, 4
The signal processing system (synthesis processing system) uses the image information from 1C and 41D, and at this time, if necessary, the third optical system 3
The first image pickup means 31 formed in 1 above is combined to pick up the entire subject image.

In the normal case where a high-resolution image is not required, the entire image of the subject is formed on the surface of the first image pickup means 31 by the third optical system 3, and the image is picked up. Image information from is used.

As described above, in this embodiment, the image obtained by the third optical system 3 and the fourth optical system 4 are used when a high-resolution image is required and when it is not necessary. It is configured so that the obtained composite image can be arbitrarily selected and output.

In this embodiment, the optical axes of the third optical system 3 and the fourth optical system 4 are arranged so that they do not coincide with each other, and
The subject image formed on the next image forming surface 21 is re-imaged on the corresponding image pickup element surface at a desired degree of overlap and magnification.

Further, in the present embodiment, the sum of the plurality of divided images formed by the fourth optical system 4 is configured so as to include the entire area of the subject image formed by the first optical system 1. That is, as will be described later, the adjacent divided images are configured to overlap each other with pixels in the boundary portion, so that no inconvenience occurs in the image boundary portion.

FIG. 3 is an explanatory view showing the overlap of the boundary portion when the divided images formed on the four image pickup devices 41A, 41B, 41C and 41D corresponding to the entire area of the subject image are combined.

In the figure, for example, the boundary portion 41E between the pixels of the image pickup element 41A and the image pickup element 41B is the image pickup element 4 of each image pickup element 4A.
By extracting the corresponding pixels included in 1A and 41B when they are combined in the signal processing system, it is possible to continuously output the image of the boundary portion without interruption.

FIG. 4 is a cross-sectional view of essential parts showing the optical action of the deflecting element as the first optical member 22 according to the first embodiment of the present invention. In the figure, the same elements as those shown in FIG. 1 are designated by the same reference numerals.

In the figure, the pupil 4C1 (4D1) of the fourth optical system 4 is moved to the first optical system 1 by the first optical member 22.
The deflection direction is set to be different for each incident position of the light flux so as to form an image on the optical axis. With this, an appropriate pupil position is obtained.

The deflecting element 22 in this embodiment may be composed of, for example, a transmissive optical element having a fine diffraction pattern, and this optical element is formed on at least one lens surface of the field lens 23. If so, the size of the entire apparatus can be reduced.

Next, the image processing method of this embodiment will be described with reference to FIG. FIG. 5 is a block diagram of a main part of a signal processing system of the image pickup apparatus of this embodiment.

In this embodiment, for example, when a high resolution image is to be obtained, the image pickup devices 41A and 4A shown in FIG.
The sample and hold circuits (S / H circuits) 51A, 51B, 51C and 51 are provided with the electric signals from 1B, 41C and 41D.
Each sample is held by D, and each analog-digital conversion circuit (A / D conversion circuit) 52A, 52B, 52C, 52D
The analog signal is converted into a digital signal by and stored in each memory (storage circuit) 53A, 53B, 53C, 53D. Then, each memory 53A,
Information is read from 53B, 53C, and 53D and combined by the image combining processing circuit 54 to obtain a high-resolution image.

If necessary, the image from the first image pickup means 31 is sampled and held by the sample and hold circuit 55, converted into a digital signal by the A / D conversion circuit 56, and the image stored in the memory 57 is used. I am trying.

On the other hand, in the case of obtaining a normal image which does not require high resolution, the sample and hold circuit (S / H circuit) 55 samples and holds the electric signal from the image pickup device 31 shown in FIG. -Digital conversion circuit (A /
An analog signal is converted into a digital signal by a D conversion circuit) 56 and stored in a memory (storage circuit) 57. Then, the information from the memory 57 is read out and processed by the image processing circuit to obtain a normal image.

In this embodiment, the entire screen of the subject image is divided into four parts, and the respective divided images are combined by the signal processing system (combining processing system) to obtain one high resolution image. However, the number of pixels can be substantially increased by arbitrarily increasing the number of four lens systems constituting the fourth optical system and the number of image pickup elements corresponding to the lens systems, and thus, a higher resolution image can be obtained. Can be obtained.

Further, in the case of a still image, a higher resolution image can be obtained by using it together with the above-mentioned conventional pixel shifting method.

[0051]

According to the present invention, by appropriately configuring each element of the image pickup apparatus as described above, it is possible to obtain a high-resolution image by using the image pickup element having a limited number of pixels, and further, the photographing optical Since the back focus of the system is not limited, an image in which no inconvenience occurs at the boundary between images can be obtained, and the pupils can be matched with each other with high accuracy, and thus parallax when capturing a stereoscopic image, for example, It does not occur.

Further, an output image can be arbitrarily selected depending on whether a high-resolution image is required or not, and if the information of the image obtained by the third optical system is used, a divided image can be obtained. It is possible to achieve an image pickup device that can perform the synthesis of the images with high precision.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an optical system according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a main part of the first embodiment of the present invention.

FIG. 3 is an explanatory diagram related to image composition according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a main part of a signal processing unit according to the first embodiment of the present invention.

FIG. 5 is a sectional view of an essential part showing an optical action of the deflection element according to the first embodiment of the present invention.

[Explanation of symbols]

1 1st optical system 2 2nd optical system 3 3rd optical system 4 4th optical system 21 1st imaging surface 22 1st optical member 23 2nd optical member 31 1st imaging means 41 1st 2 image pickup means 4A, 4B, 4C, 4D lens systems 41A, 41B, 41C, 41D image pickup elements 51A, 51B, 51C, 51D sample hold circuit 55 sample hold circuits 53A, 53B, 53C, 53D A / D conversion circuit 56A / D conversion circuit 55A, 55B, 55C, 55D memory 57 memory 54 image synthesis processing circuit 58 image processing circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-58-76807 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04N 5/222-5/257 H04N 5 / 335 H04N 9/04-9/11

Claims (7)

(57) [Claims] 1. A second optical system which forms a subject image on a planned image forming plane by the first optical system, and is arranged on the optical axis of the first optical system and near the planned image forming plane. A first image pickup means for all the subject images formed on the planned image forming surface by the third optical system arranged on the optical axis of the first optical system and behind the second optical system. Image formed on the planned image forming plane by the fourth optical system which is re-imaged on the optical axis and has an optical axis outside the optical axis of the first optical system, and which is arranged behind the second optical system. Device for re-imaging a part of the image on the second image pickup means and obtaining high-definition image information by using image information obtained by the first image pickup means and the second image pickup means The second optical system has an optical member in which the directivity of the light flux differs depending on the incident position. 2. The fourth optical system has a plurality of lens systems, and the second image pickup means has a plurality of image pickup devices corresponding to the plurality of lens systems. The image pickup apparatus according to claim 1. 3. The plurality of lens systems of the fourth optical system are provided on respective image pickup element surfaces of object images of respective areas when the object image formed by the first optical system is divided into a plurality of areas. The image pickup apparatus according to claim 2, wherein the image is formed on the image. 4. One piece of image information is obtained by utilizing image information obtained from a plurality of image pickup devices constituting the second image pickup means and image information obtained from the first image pickup means. The imaging device according to claim 2 or 3, characterized in that 5. The second optical system has a first optical member having a directivity of a light beam that differs depending on an incident position and a second optical member having a positive refractive power. Item 1. The imaging device according to item 1. 6. A second optical system which forms a subject image on a planned image forming surface by the first optical system, and has the same optical axis as the first optical system arranged near the planned image forming surface, First image pickup of all the subject images formed on the planned image forming plane by the third optical system which is arranged behind the second optical system and whose optical axis coincides with that of the first optical system. An image is formed on the plane of the means and the first
Obtain image information about all the object image from the image pickup means Rutotomoni, a plurality of dividing the object image formed on the predetermined imaging plane
The area was placed have a plurality of lens system behind the second optical system having an optical axis different from the optical axis of the first optical system 4
On the surface of the plurality of image pickup elements of the second image pickup means having a plurality of image pickup elements corresponding to the plurality of lens systems by the optical system of
The second optical system is an image pickup apparatus which forms images respectively and synthesizes image information from the plurality of image pickup elements to obtain image information about an entire subject image. An imaging device having different optical members. 7. The second optical system includes a first optical member having a directivity of a light beam that differs depending on an incident position and a second optical member having a positive refracting power. Item 6. The imaging device according to item 6.