JP3397403B2 - 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]

According to a first aspect of the present invention, there is provided an image pickup apparatus, wherein a first optical system forms a subject image on a predetermined image formation plane, and the image is formed on the optical axis of the first optical system. The second optical system arranged near the planned image forming surface and the third optical system arranged on the optical axis of the first optical system and behind the second optical system form the planned image formation. All of the subject images formed on the surface are re-imaged on the first image pickup means, have an optical axis outside the optical axis of the first optical system, and are arranged behind the second optical system. Part of the subject image formed on the planned image forming surface by the optical system of FIG. 2 is re-imaged on the second image pickup means, and the image information obtained by the first image pickup means and the second image pickup means is used. It is characterized by obtaining high-definition image information.

According to another aspect of the image pickup apparatus of the present invention, a subject image is formed on the planned image forming surface by the first optical system, and the object image is formed on the optical axis of the first optical system and near the planned image forming surface. An optical path splitting means is provided in the optical path between the arranged second optical system and the first optical system and the second optical system, and the first optical path of one optical path split by the optical path splitting means is provided. A fifth optical system is provided in the vicinity of the planned image plane of the optical system, and the third optical system is arranged on the optical axis of the first optical system and behind the fifth optical system. All the object images formed on the image plane are re-imaged on the first image pickup means, and the first optical path of the other optical path split by the optical path splitting means.
Has an optical axis outside the optical axis of the second optical system, and a part of the subject image formed on the planned image forming surface by the fourth optical system arranged behind the second optical system is used as a second imaging means. Re-imaging is performed, and high-definition image information is obtained by using the image information obtained by the first image pickup means and the second image pickup means.

According to a third aspect of the invention, in the first or second aspect of the invention, the fourth optical system has a plurality of lens systems, and the second image pickup means corresponds to the plurality of lens systems. It is characterized by having a plurality of image pickup elements. According to a fourth aspect of the present invention, in the third aspect of the present invention, the plurality of lens systems of the fourth optical system divides the subject image formed by the first optical system into a plurality of regions, and the subject images of the respective regions are divided. Is imaged on the surface of the corresponding image pickup device. According to a fifth aspect of the present invention, in the first, second, third or fourth aspect of the present invention, image information obtained from a plurality of image pickup devices forming the second image pickup means and image information obtained from the first image pickup means are provided. Is characterized in that one image information is obtained by using. According to a sixth aspect of the invention, in the first, second or third aspect of the invention, the third optical system and the plurality of lens systems of the fourth optical system have different imaging magnifications.

According to a seventh aspect of the present invention, an image pickup device forms an image of a subject 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. Second
Of the subject image formed on the planned image forming plane by the third optical system which is disposed behind the second optical system and the optical axis of the first optical system coincides with that of the first optical system. A plurality of lenses having an optical axis different from the optical axis of the first optical system, the plurality of regions obtained by forming an image on the surface of the first imaging unit and dividing the subject image formed on the planned image forming surface. A fourth optical system having a system and arranged behind the second optical system is connected on the plurality of image pickup device surfaces of the second image pickup means having a plurality of image pickup devices corresponding to the plurality of lens systems, respectively. It is characterized in that an image is formed and the image information from the plurality of image pickup elements is combined to obtain the image information regarding the entire subject image.

The invention of claim 8 is the invention of claim 7 characterized in that the plurality of lens systems of the third optical system and the fourth optical system have different imaging magnifications.

[0022]

[0023]

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 denotes a second optical system, which is the first optical system 1.
Of the subject image formed on the primary image forming surface 21 and is guided to the subsequent lens system. There is.

Reference numeral 3 denotes a third optical system, which is 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 arranged 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 image 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 image pickup devices 41A, 41B, 41.
The image is re-formed on the C and 41D planes. At that time, the centers of the light receiving surfaces of the image pickup devices 41A, 41B, 41C, and 41D are deviated from the optical axis of the lens system of the fourth optical system as shown in the drawing.

In the second embodiment, in the second optical system 2, the pupil 1a of the first optical system 1 and the pupil 3a of the third optical system 3 are substantially conjugate with each other, as indicated by the optical path 32 in the figure. I am trying. Further, as shown by an optical path 42 indicated by a broken line in the drawing, a plurality of lens systems 4A, 4B, 4C, 4D which constitute the fourth optical system 4 are formed.
The pupils 4A1, 4B1, 4C1 and 4D1 are imaged in the vicinity of the divided pupil regions of the first optical system 1, respectively.

Four lens systems (4A, 4B, 4C, 4D) of the third optical system 3 and the fourth optical system 4 in this embodiment.
The image forming magnifications of and are different from each other, which effectively aligns the pupil image formation.

In this embodiment, the second optical system 2 and the third optical system 3 constitute one element of the re-imaging optical system, and the second optical system 2 and the fourth optical system 4 are It constitutes one element of the split imaging optical system.

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 this embodiment, the image pickup elements 41A and 41B corresponding to the subject image by the fourth optical system 4 consisting of 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 image information of the first image pickup unit 31 formed in 1 is used as a reference to synthesize the entire subject image.

In a 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 the present 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 this 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 device 41A and the image pickup device 41B is the image pickup device 4 of each image pickup device.
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.

Next, the image processing method of this embodiment will be described with reference to FIG. FIG. 4 is a block diagram of a main part of a signal processing system of the image pickup apparatus of this embodiment.

In the present 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 order to obtain 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.

FIG. 5 is a schematic view of the essential parts of an optical system according to a second embodiment of the present invention. In the figure, the same elements as those shown in FIG. 1 are designated by the same reference numerals.

The present embodiment differs from the above-mentioned first embodiment in that a half mirror as an optical path splitting means is arranged in the optical path between the first optical system 1 and the second optical system 2, and the optical path is divided into two.
It is a point divided into two. An optical system (hereinafter, referred to as “fifth optical system”) 23 corresponding to the second optical system 2 is provided near an image forming position 22 that is substantially optically equivalent to the primary image forming surface 21 of one optical path. And the third optical system 3 and the first optical system
Image pickup means 31 and the fourth optical system 4 is provided in the other optical path. Other configurations and optical functions are substantially the same as those in the above-described first embodiment, and the same effect is obtained.

That is, in this embodiment, by adopting such an optical arrangement, the vignetting of the light beam is prevented and the degree of freedom in the optical arrangement is obtained. Further, since the refractive powers of the respective lenses of the second optical system 2 and the fifth optical system 23 can be individually set, an appropriate pupil imaging relationship is obtained on-axis and off-axis.

In this embodiment, the half mirror is used as the optical path splitting means, but instead of the half mirror, for example, a rotatable mirror may be used. As a result, it is possible to guide the light to each image sensor without reducing the light amount of the light flux.

In each of the above embodiments, the entire screen of the subject image is divided into four parts, and each divided image is combined by the signal processing system (combining processing system) to obtain one high resolution image. I got an image, but I am constructing a fourth optical system.
The number of pixels can be substantially increased by arbitrarily increasing the number of one lens system and the number of image pickup devices corresponding to the lens system, whereby an image with higher resolution can be obtained.

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

[0054]

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 An image that does not cause inconvenience at the boundary between images can be obtained without limiting the back focus of the system, and an output image can be arbitrarily selected depending on whether a high-resolution image is required or not. Can be third
By using the information of the image obtained by the optical system, it is possible to achieve an image pickup apparatus capable of synthesizing divided images with high accuracy.

[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 schematic view of a main part of an optical system according to a second embodiment of the present invention.

[Explanation of symbols]

1 1st optical system 2 and 23 2nd optical system 3 3rd optical system 4 4th optical system 5 5th optical system 21 and 22 1st image formation plane 31 1st image pickup expedient 41 2nd Imaging means 4A, 4B, 4C, 4D Lens systems 41A, 41B, 41C, 41D Imaging elements 51A, 51B, 51C, 51D Sample hold circuit 55 Sample hold circuits 53A, 53B, 53C, 53D A / D conversion circuit 56 A / D Conversion circuits 55A, 55B, 55C, 55D Memory 57 Memory 54 Image synthesis processing circuit 58 Image processing circuit

Front page continuation (72) Inventor Eiyu Ogura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Nobuhiro Takeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masashi Hori 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasuyuki Yamazaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Invention Person Yoshihiro Honma 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Toshikazu Yanai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Masato Kosugi Tokyo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference 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 (8)

(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. re-imaging, and has an optical axis out of the optical axis of the first optical system, a fourth optics arranged behind the second optical system
The second image of a part of the subject image formed on the planned image plane by the system
An image pickup device characterized in that high-definition image information is obtained by re-imaging on an image means and utilizing image information obtained by the first image pickup means and the second image pickup means. 2. 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. , An optical path splitting means is provided in the optical path between the first optical system and the second optical system,
A fifth optical system is provided near one of the optical paths split by the optical path splitting means in the vicinity of a planned image formation plane of the first optical system, and the fifth optical system is on the optical axis of the first optical system. A third optical system disposed behind the system reimages all of the subject image formed on the planned image forming surface on the first image pickup means, and the other optical path of the other optical path split by the optical path splitting means. A second image capturing part of the subject image formed on the planned image forming plane by a fourth optical system having an optical axis outside the optical axis of the first optical system and arranged behind the second optical system. An image pickup apparatus characterized in that high-definition image information is obtained by re-forming an image on the means and utilizing image information obtained by the first image pickup means and the second image pickup means. 3. 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 imaging device according to claim 1 or 2. 4. The plurality of lens systems of the fourth optical system are provided on respective image pickup device surfaces of subject images of respective regions when the subject image formed by the first optical system is divided into a plurality of regions. The image pickup device according to claim 3, wherein the image is formed on the image pickup device. 5. One piece of image information is obtained 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 image pickup apparatus according to claim 1, 2, 3, or 4. 6. The image pickup apparatus according to claim 1, wherein the third optical system and the plurality of lens systems of the fourth optical system have different imaging magnifications. 7. A subject image is projected by the first optical system.
First optics which is imaged on a plane and is arranged near the planned image plane
A second optical system having the same optical axis as the optical system and the second optical system
Arranged at the rear with the optical axis of the first optical system aligned
Formed on the planned image forming surface by the third optical system
The entire image is formed on the surface of the first image pickup means, and
Subject image formed on the planned image planeMultiple regions
A plurality of optical axes having an optical axis different from the optical axis of the first optical system.
With lens systemPlaced behind the second optical systemFourth light
Multiple imaging devices corresponding to the multiple lens systems depending on the academic system
On the plurality of image pickup device surfaces of the second image pickup means having
Form an image and combine the image information from the multiple image sensors
The feature is that image information about all subject images is obtained.
Image pickup device. 8. The image pickup apparatus according to claim 7, wherein the third optical system and the plurality of lens systems of the fourth optical system have different imaging magnifications.