JP2002135796A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of obtaining color images with high sharpness by using an imaging optical system of short optical path length with simple configuration. SOLUTION: The apparatus comprises two or more openings 52a, 52b, 52c to take in lights from the outside through different position and an imaging element 120 receiving respectively the lights captured from the openings 52a, 52b, 52c and having two or more imaging areas 53a, 53b, 53c to extract prescribed color components at every light from the outside gathered independently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-sized image pickup apparatus to which a solid-state image pickup device such as a digital electronic still camera or a video movie camera is applied.

[0002]

2. Description of the Related Art In a digital color camera, an object image is exposed to a solid-state image sensor such as a CCD or CMOS sensor for a desired time in response to pressing of a release button. An image signal representing an image is converted into a digital signal and subjected to predetermined processing such as YC processing to obtain an image signal in a predetermined format. A digital image signal representing a captured image is recorded in a semiconductor memory for each image. The recorded image signal is read out at any time, reproduced into a displayable or printable signal, output to a monitor or the like, and displayed.

[0003] As one of the techniques of a digital color camera, an example disclosed in Japanese Patent Application Laid-Open No. Hei 7-123418 is known. Japanese Patent Application Laid-Open No. Hei 7-123418 discloses that an object image on a predetermined imaging plane is re-imaged by a plurality of re-imaging optical systems, and each object image is captured via an optical filter having a different spectral transmittance characteristic. Things. It is convenient to obtain a high-resolution color image using an image sensor having a limited number of pixels.

[0004]

However, when this technology is applied to a small digital color camera, there are the following problems. (1) Since the object image is formed on the image sensor via the re-imaging optical system, the entire optical path length is long, and it is difficult to reduce the size of the camera. (2) Since the distortion of a plurality of re-imaging optical systems is generated line-symmetrically with respect to the optical axis of the primary imaging optical system, if the distortions are to be aligned between the re-imaging optical systems, the re-imaging optics will not work. The configuration of the system becomes extremely complicated. That is, it is difficult to obtain an optical system that completely overlaps the images of the respective colors. (3) Further, since the image of each color is formed by a light beam passing through a part of the pupil of the primary imaging optical system, optical aberrations such as spherical aberration, coma, and field curvature are also reduced with respect to the center of each imaging region. And a sharpness is likely to be reduced in the synthesized color image.

Accordingly, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to obtain a color image with high sharpness using an imaging optical system having a short optical path length with a simple configuration. An object of the present invention is to provide an imaging device.

[0006]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, an imaging apparatus according to the present invention includes a plurality of openings for capturing external light from different positions, and separately receives the external light captured from the plurality of openings, and receives the separate light. A plurality of image pickup means for extracting a predetermined color component for each external light.

Further, in the image pickup apparatus according to the present invention, the plurality of image pickup means include a plurality of optical systems for forming an image of the external light taken in from the aperture.

Further, in the imaging apparatus according to the present invention, each of the plurality of optical systems has a single lens.

In the image pickup apparatus according to the present invention, the plurality of optical systems are three optical systems.
The three single lenses corresponding to the three optical systems each include an optical filter that transmits red light, an optical filter that transmits green light, and an optical filter that transmits blue light.

Further, in the imaging apparatus according to the present invention, the plurality of single lenses constituting the plurality of optical systems are integrally formed by molding a glass material or a resin material.

Further, in the imaging apparatus according to the present invention, a light-shielding film is formed at a portion between the plurality of single lenses in a molded body obtained by integrally forming the plurality of single lenses. .

Further, in the image pickup apparatus according to the present invention, the plurality of single lenses are provided with an infrared cut filter.

Further, in the image pickup apparatus according to the present invention, the plurality of image pickup means include one image pickup element having a plurality of image pickup areas corresponding to the plurality of openings, respectively.

In the imaging apparatus according to the present invention, the plurality of imaging areas are three imaging areas,
The three imaging regions each include an optical filter that transmits red light, an optical filter that transmits green light,
It is characterized by having an optical filter that transmits blue light.

Further, in the imaging apparatus according to the present invention, the plurality of imaging units include a plurality of apertures corresponding to the plurality of apertures.

[0016]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

(First Embodiment) FIGS. 17, 18 and 1
FIG. 9 is a diagram illustrating an entire configuration of a digital color camera according to the first embodiment of the present invention. FIG. 17 is a front view, FIG.
8 is a rear view, and FIG. 19 is a cross-sectional view at the position of arrow A in FIG.

In FIGS. 17, 18 and 19, reference numeral 1 denotes a camera main body, and 2 denotes an illumination light take-in window which is located behind the color liquid crystal monitor 4 and is made of a white diffusion plate. 5 is a main switch, 6 is a release button, 7, 8 and 9 are switches for the user to set the state of the camera, and especially 9 is a playback button. Reference numeral 13 denotes a display of the remaining number of images that can be taken. Reference numeral 11 denotes a finder eyepiece window, from which object light entering the prism 12 from the finder front frame 3 is emitted. Reference numeral 10 denotes an imaging system, and 14 denotes a connection terminal for connecting to an external computer or the like to transmit and receive data.

The schematic configuration of the signal processing system will be described.

FIG. 14 is a block diagram of a signal processing system. This camera is a single-panel digital color camera using a solid-state imaging device 120 such as a CCD or a CMOS sensor, and continuously or spontaneously drives the solid-state imaging device 120 to generate an image signal representing a moving image or a still image. obtain. Here, the solid-state imaging device 120 is a type of imaging device that converts exposed light into an electric signal for each pixel, accumulates charges corresponding to the amount of light, and reads out the charges.

In the drawings, only parts directly related to the present invention are shown, and parts not directly related to the present invention are omitted from the drawings and description.

As shown in FIG. 14, the image pickup apparatus comprises an image pickup system 10 and an image processing system 20 serving as image processing means.
And a recording / reproducing system 30 and a control system 40. Further, the imaging system 10 includes a photographing lens 100, an aperture 110, and a solid-state imaging device 120, and the image processing system 20 includes an A / A
D converter 500, RGB image processing circuit 210 and YC
The recording / reproducing system 30 includes a recording processing circuit 300 and a reproducing processing circuit 310, and includes a control system 40.
Includes a system control unit 400, an operation detection unit 410, and a solid-state imaging device drive circuit 420.

The imaging system 10 stops light from an object by
And an optical processing system that forms an image on the imaging surface of the solid-state imaging device 120 via the imaging lens 100.
Exposure to zero. As described above, the solid-state imaging device 120 includes:
An imaging device such as a CCD or a CMOS sensor is effectively applied, and by controlling the exposure time and exposure interval of the solid-state imaging device 120, an image signal representing a continuous moving image or an image representing a still image by one exposure A signal can be obtained.

FIG. 1 is a detailed view of the image pickup system 10. First,
The stop 110 has three circular openings 110 as shown in FIG.
a, 110b, and 110c, and object light incident on the light incident surface 100e of the photographing lens 100 from each of the three lens portions 100a, 100b, 1
3c on the imaging surface of the solid-state imaging device 120
To form two object images. Aperture 110 and light incident surface 100e
The imaging plane of the solid-state imaging device 120 is arranged in parallel. As described above, by reducing the power on the incident side, increasing the power in the emission example, and providing the stop on the incident side, the curvature of the image plane can be reduced. Here, the light incident surface 100e of the photographing lens 100 is a plane, but may be formed of three spherical surfaces or three rotationally symmetric aspheric surfaces.

The three lens parts 100a, 100b, 10
0c has a spherical portion having a circular diameter as shown in FIG. 5 when the photographing lens 100 is viewed from the light emission side, and the spherical portion has 670n.
An infrared cut filter having a low transmittance in a wavelength range of m or more is formed, and a light-shielding film is formed on a flat portion 100d indicated by hatching. That is, the photographing optical system includes the photographing lens 100 and the aperture 110, and each of the three lens units 100a, 100b, and 100c is an imaging system.

When the photographic lens 100 is made of glass, a glass mold manufacturing method is used, and when the photographic lens 100 is made of a resin, injection molding is used.

FIG. 2 is a front view of the solid-state image pickup device 120. The three image pickup areas 12 corresponding to three object images to be formed are shown.
0a, 120b, and 120c. Imaging area 12
0a, 120b, and 120c are each formed by arranging 800 × 600 pixels having a vertical and horizontal pitch of 2.8 μm.
It is an area of 24 mm × 1.68 mm, the overall size of the imaging area is 2.24 mm × 5.04 mm, and the diagonal dimension of each imaging area is 2.80 mm. In the figure, 51
a, 51b, and 51c are image circles in which an object image is formed. Image circles 51a, 51b,
Reference numeral 51c denotes a circular shape determined by the aperture of the stop and the size of the spherical portion on the exit side of the photographing lens 100.
1a and 51b, and image circles 51b and 51
c has portions overlapping each other.

Returning to FIG. 1, aperture 110 and taking lens 1
A hatched portion 52a of the area sandwiched between 00,
52b and 52c are light incident surfaces 100e of the photographing lens 100.
An optical filter formed thereon. The optical filters 52a, 52b, and 52c are provided with aperture openings 110a, 110a as shown in FIG.
b, 110c.

The optical filter 52a has a spectral transmittance characteristic indicated by G in FIG. 6 that mainly transmits green, and the optical filter 52b has a spectral transmittance characteristic indicated by R that mainly transmits red. Further, the optical filter 52c has a spectral transmittance characteristic indicated by B, which mainly transmits blue light. That is, these are primary color filters. Lens unit 10
0a, 100b, and 100c, the product of the characteristics of the infrared cut filter and the image circle 5
The object image formed on the image circle 1a has a green light component, the object image formed on the image circle 51b has a red light component, and the object image formed on the image circle 51c has a blue light component.

On the other hand, optical filters 53a, 53b, and 53c are also formed on the three imaging regions 120a, 120b, and 120c of the solid-state imaging device 120, and their spectral transmittance characteristics are also the same as those shown in FIG. Are equivalent. That is, the imaging area 120a is for the green light (G), the imaging area 120b is for the red light (R), and the imaging area 120c is
Has sensitivity to blue light (B).

Since the light receiving spectrum distribution of each imaging region is given as the product of the pupil and the spectral transmittance of the imaging region, the combination of the pupil and the imaging region is selected according to the wavelength range. That is, the object light that has passed through the aperture 110a of the aperture is mainly photoelectrically converted in the imaging area 120a, the object light that has passed through the aperture 110b of the aperture is mainly photoelectrically converted in the imaging area 120b, and further has passed through the aperture 110c of the aperture. The obtained object light is photoelectrically converted mainly in the imaging region 120c. That is, imaging area 1
20a outputs a G image, the imaging region 120b outputs an R image, and the imaging region 120c outputs a B image. As described above, by using multiple optical filters for color separation in the pupil of the imaging optical system and the imaging device, the color purity can be increased. This is because, when the same type of optical filter is passed twice, the transmission characteristics sharply rise and the overlap between red (R) and blue (B) is eliminated. In addition,
The optical filters 52a, 52b, and 5c are set so that the signal level in each imaging region becomes appropriate in the same accumulation time.
2c or the transmittance of the optical filters 53a, 53b, 53c may be set.

In the image processing system 20, a plurality of imaging regions of the solid-state imaging device 120 form a color image based on a selective photoelectric conversion output obtained from one of the plurality of images. At this time, since the peak wavelength of relative luminous efficiency is 555 nm, signal processing is performed using a G image signal including this wavelength as a reference image signal.

Assuming that the pixel pitch of the solid-state image sensor is fixed, an RGB color filter having a set of, for example, 2 × 2 pixels is formed on the solid-state image sensor to provide wavelength selectivity to each pixel. This reduces the size of the object image to 1 / √3 as compared with the method used in a general digital color camera that separates an object image into RGB images. The focal length is approximately 1 /
$ 3. Therefore, it is extremely advantageous for a book-type camera.

The optical filters 52a, 52b, 5
As shown in FIG. 6, the spectral transmittance characteristics of 2c and the optical filters 53a, 53b, 53c are such that R and B are almost separated from each other, but R and G and G and B overlap each other. .

Therefore, the red light image circle 5
1b is applied to the imaging region 120c for photoelectrically converting blue light, or conversely, even if the image circle 51c of blue light is applied to the imaging region 120b for photoelectrically converting red light, these images are output from the imaging region. Will not be.
However, a portion where the red light image circle 51b covers the imaging region 120a for photoelectrically converting green light,
In a portion where the green light image circle 51a covers the imaging region 120b for photoelectrically converting red light, images of different wavelengths that should be cut off are superimposed, albeit slightly. That is, the selectivity of the object image is given by the product of the spectral transmittance characteristics of the optical filter 52a and the optical filter 53b and the product of the spectral transmittance characteristics of the optical filter 52b and the optical filter 53a. Crosstalk is small but not completely zero.

Therefore, the photographing lens 100 is further provided with a characteristic of lowering the transmittance in the wavelength region of the overlapping portion of R and G. For this, an optical filter technique called a color purity correction filter may be used.

This color purity correction filter is an optical filter in which a predetermined amount of rare earth metal ions is contained in a base material made of a transparent synthetic resin or glass.

The rare earth metal ion includes one or more of neodymium ion, praseodymium ion, erbium ion, holmium ion and the like, and it is preferable to use at least neodymium ion as an essential ion. Incidentally, these ions are usually 3
Valent ions are used. The content of the metal ion is selected from the range of usually 0.01 to 40 parts by mass, preferably 0.04 to 30 parts by mass with respect to 100 parts by mass of the base material of the photographic lens 100.

As shown in FIG. 7, the color purity correction filter has a characteristic of selectively absorbing light in a predetermined wavelength range between peak wavelengths of each of the RGB color components to reduce the amount of transmission. By this action, the crosstalk caused by the red light image circle 51b covering the imaging region 120a for photoelectrically converting green light and the green light image circle 51a covering the imaging region 120b for photoelectrically converting red light is almost eliminated. No longer occurs.

Further, the photographic lens 100 is provided with a photochromic property, which is a phenomenon of reversibly returning to a colorless state when the light is darkened and light irradiation is stopped. This is because, since the storage time control range of the solid-state imaging device 120 is limited, the amount of light reaching the solid-state imaging device when the field is extremely bright is suppressed, and the luminance range in which photography can be performed is expanded.

As the photochromic glass, for example, a phosphate-based photochromic glass (trade name: Reactolite Rapide) manufactured by Chance Pilkington Co., Ltd., which is put into practical use for eyeglasses, may be used.

FIG. 8 is a diagram showing the spectral transmittance characteristics of the photochromic glass used for the photographing lens 100. In FIG. 8, the solid line shows the characteristics after irradiating the solar light for 20 minutes, and the broken line shows the case where no irradiation is performed. It shows the characteristics of the above. When the camera is carried around outdoors in fine weather, the luminous flux entering the photographic lens 100 from the aperture 110 causes the photographic lens 10
0 itself darkens, and the amount of light incident on the solid-state imaging device 120 can be suppressed to about ２. As a result, the accumulation time can be doubled, and the control limit on the high luminance side is raised.

Each of the imaging areas 120a, 120b, 120c
Has a pixel pitch of 2.8 μm as described above,
2.24 mm x 1.68 m from 800 x 600 pixels
m, and the diagonal size of the screen is 2.80 mm. Generally, it is easiest to use a small camera at an angle of view θ of about 70 ° in a diagonal direction. Assuming that the shooting angle of view is 70 °, the focal length is determined from the diagonal size of the screen. In this case, the focal length is 2.0 mm.

When a person or the like is to be photographed, the virtual subject distance D is based on the fact that the height of a human is around 170 cm and that one to three persons are often photographed together.
[M] can be defined as a function of the imaging angle of view θ [°] as in Expression (1).

D = 1.4 / tan (θ / 2) (1) By substituting 70 ° into θ in the equation (1), D = 2.0 m is obtained. Therefore, if the imaging system 10 is configured to achieve the best focus when the subject distance is 2 m, the lens extension from the infinity position is 0.002 mm, and the lens extension from the relationship with the allowable confusion circle diameter described later. There is no practical problem at all even as a fixed-focus imaging optical system without a mechanism.

The focal length f of the plano-convex lens placed in the air is represented by f = {1 / (1-n)}. R (2) where n is the refractive index and r is the radius of the spherical surface. Can be. Therefore, if the photographing lens 1 is
If the refractive index n of 00 is 1.5, r for obtaining a focal length of 2.0 mm is 1.0 mm.

If the size of each of the red, green, and blue object images is made uniform, it is not necessary to perform image magnification correction in subsequent signal processing, so that the processing time is not extended, which is convenient. Therefore, the lens units 100a, 100b, and 100c are optimized for peak wavelengths of transmitted light of the RGB optical filters of 530 nm, 620 nm, and 450 nm, and each image magnification is set to be constant. This can be realized paraxially by making the distance from the principal point position of each lens unit to the solid-state imaging device uniform.

The refractive index nd of the d-line (587.6 nm) =
In the case of 1.5 and Abbe number νd = 60 glass, the wavelength 53
The refractive indexes at 0 nm, 620 nm, and 450 nm are about 1.503, 1.499, and 1.509, respectively. Assuming that the radii r of the spherical surfaces of the lens units 100a, 100b, and 100c are uniformly -1.0 mm, the focal lengths at these wavelengths are as follows from Expression (2).

Lens part 100a Representative wavelength 530 nm:
1.988mm lens part 100b, representative wavelength 620nm: 2.004m
m Lens part 100c Representative wavelength 450 nm: 1.965 m
Assuming that the permissible circle of confusion is 3.0 μm from the m pixel pitch and the F number of the photographing lens is F5.6,
The depth of focus expressed by these products is 16.8 μm,
0.039mm difference between focal length of 620nm and 450nm
Is already over this. That is, although only the paraxial image magnification is uniform, it is not focused depending on the color of the subject. In general, the spectral reflectance of an object extends over a wide wavelength range, so that sharp focus is generally rarely obtained.

Therefore, the lens units 100a, 100b, 1
The radius r of the spherical surface of 00c is optimized for each representative wavelength. That is, here, achromatic design for removing chromatic aberration in the entire visible range is not performed, and a design for each wavelength is applied to each lens. First,
By transforming equation (2), equation (3) is obtained.

R = (1−n) f (3) In equation (3), f = 2.0 and sequentially n = 1.503, n = 1.
499, n = 1.509 is substituted and each radius is calculated as follows.

Lens part 100a Representative wavelength 530 nm:
r = -1.006 mm Lens part 100b Representative wavelength 620 nm: r = -0.9
98mm lens part 100c, representative wavelength 450nm: r = -1.0
18mm To balance the image magnification difference at a high image height,
If the vertex heights of the lens units 100a, 100b, 100c are slightly adjusted, an ideal shape can be obtained with respect to both sharpness and image magnification. Furthermore, an aspherical surface is used for each lens unit to satisfactorily correct field curvature. The image distortion may be corrected in the subsequent signal processing. In this manner, the reference G image signal based on the object light including the wavelength of green 555 nm having the highest visibility and the image signal based on the red and blue object lights are obtained, and the imaging system differs for a single wavelength. If the focal length is set to be substantially the same for the representative wavelength of each spectral distribution, a color image in which chromatic aberration is well corrected can be obtained by combining these image signals. Since each image forming system has a single structure, there is also an effect of reducing the thickness of the imaging system. Further, achromatization usually requires a combination of two lenses having different dispersions, but the use of a single lens has an effect of cost reduction.

The photographing lens 100 is required to have a high-contrast resolution up to a high spatial frequency band up to the same level as the pixel pitch. Since the imaging system 10 captures three object images for each wavelength range, when compared with an imaging system having the same number of pixels having a mosaic optical filter such as a Bayer array,
As described above, the same shooting angle of view is obtained at a focal length of about 1 / √3. Therefore, high-contrast resolution of higher spatial frequency components must be realized. The wavelength-specific optimization of each lens unit described above is a chromatic aberration suppressing technique for this purpose.

In general, there are methods for improving the aberration characteristics of the photographing optical system so that false resolution is less likely to occur and the problem is reduced.
(1) Increasing the number of constituent lenses, asphericalizing, using an abnormal fractional glass, using a diffractive optical element in combination,
To increase design flexibility by using several methods, such as
(2) There are two ways of narrowing the imaging light beam.

The direction (1) that increases the degree of freedom in design complicates the configuration of the photographing optical system even though the focal length is reduced to 1 / √3. It is not appropriate because it will go backwards. On the other hand, the direction (2) using a thin light beam has good compatibility with a thin imaging device.

When the imaging light beam is stopped down, the response function called OTF gradually decreases monotonously in the low frequency component as shown by the solid line (b) in FIG. 10, then takes a slightly negative value and then slightly again. The characteristic has a positive value. on the other hand,
In the case where a thick light beam is used without narrowing down the image forming light beam, as shown by a dashed line (a) in FIG. 10, the characteristic rapidly decreases in the low frequency component, then takes a negative value and then takes a positive value. .

A state in which the OTF takes a negative value indicates the occurrence of false resolution. In an actual image, a white portion becomes black and a black portion becomes white, which corresponds to a negative-positive inversion phenomenon. Therefore, it can be seen that a natural image can be obtained by narrowing the imaging light flux.

However, when the light beam is narrowed down extremely, the contrast of the high-frequency region is reduced by the influence of light diffraction. In such a situation, the point image is composed of a central bright spot and diffraction fringes surrounding the central bright spot several times. The reason for this is, as is well known, that the intensity of diffraction fringes due to peripheral waves emitted from the edge of the aperture opening relatively increases.

In order to reduce diffraction fringes, a filter may be added to the photographic lens so that the center is transparent and the density increases toward the periphery. This method is called apodization and is an enhanced version of the Optical Technology Handbook (Showa 50
Year, Asakura Shoten) on pages 172 to 174.

FIG. 9 shows the light incident surface 100 of the photographing lens 100.
e, the aperture openings 110a, 110b, 110c
FIG. 7 is a diagram illustrating a transmittance distribution of a transmittance distribution type filter provided at a position facing the light emitting device; Figure 1 shows the transmittance distribution type filter.
54a, 54b and 54c, the position where the transmittance is highest coincides with the center of the aperture openings 110a, 110b and 110c, and the position where the transmittance becomes zero is the aperture opening 110a,
The edges 110b and 110c are aligned. That is,
The transmittance distribution is highest at the center of the stop, and monotonically decreases as the distance from the center increases.

The transmittance distribution type filter is used for the photographing lens 10.
A thin film of Inconel, chromel, chrome, or the like is formed on the light incident side of No. 0 by vapor deposition or sputtering. The characteristics shown in FIG. 9 can be obtained by making the thickness of the thin film the thinnest in the central part and the thickest in the peripheral part. In the formation of such a thin film, the position of the shield in the vapor deposition or sputtering process is continuously controlled.

Here, the transmittance distribution type filter 54
Although a, 54b and 54c are formed on the taking lens, they may be formed on a glass plate and arranged on the light incident side or the light emitting side of the taking lens 100.

FIG. 11 is a diagram showing a luminance distribution of a point image.
In the figure, the dashed line (a) shows the case where the transmittance of the aperture opening is constant, and the solid line (b) shows the case where the transmittance of the aperture opening decreases from the center to the periphery. (B) for the characteristics of (a)
Characteristics show no rebound at the foot of the point image, and clearly shows a good image. This is a manifestation of the effect of reducing diffraction fringes by reducing peripheral light beams by apodization.

Next, the positional relationship between the photographing lens and the image pickup area will be described. Since the imaging system has three lens units, the positions of the three object images relatively change according to the subject distance. As described above, each imaging area is 2.24 mm ×
1.68 mm, which are arranged adjacent to each other so that the long sides are in contact with each other. Therefore, the center interval between adjacent imaging regions is 1.68 mm. The YC processing circuit 230 described later performs signal processing on the assumption that the center of the object image matches the center of the imaging region. Virtual subject distance 2m
Is formed on the image pickup unit at the same interval, the distance between the lens units 100a, 100b, and 100c of the photographing lens 100 is set to 1.67883 as shown in FIG.
mm. In the figure, arrows 55a, 5
5b and 55c are three lens units 1 of the photographing lens 100.
00a, 100b, 100c, a symbol representing an imaging system having a positive power, rectangles 56a, 56b, 56c represent symbols of a range of imaging regions 120a, 120b, 120c,
L1, L2, and L3 are optical axes of the imaging systems 55a, 55b, and 55c. Since the light incident surface of the photographing lens 100 is a flat surface, and the lens portions 100a, 100b, and 100c, which are light exit surfaces, are spherical, a straight line passing through each spherical center and perpendicular to the light incident surface 100e is the optical axis.

At this time, since the image of the object at infinity is formed at the same interval as the lens units 100a, 100b, and 100c as shown in FIG. 13, the interval between the G object image and the R object image, and the R object image The distance between the object image and the object B is 1.6783 mm. Therefore, the distance ΔY is slightly smaller than the center interval of the imaging region of 1.68 mm, and the difference ΔY is 0.0017 mm, that is, 1.7 μm. Further, when the movement of the B object image is considered with reference to the G object image having the highest visibility, the difference ΔY is doubled and is 3.4 μm. Near objects such as people are often located in the center of the shooting screen, and distant objects are often located around the screen.Furthermore, near the screen, the aberration of the shooting lens increases and image performance deteriorates. Therefore, if the maximum image interval change is smaller than twice the pixel pitch, it can be said that there is no practical problem. As described above, the solid-state imaging device 1
20 is 2.8 μm, so that ΔY <2
× P, and this degree of color shift of the image at infinity is at an acceptable level.

Further, the image interval also fluctuates due to a temperature change of the image pickup system 10. Assuming that the linear expansion coefficient of the solid-state imaging device 120 is αS, the linear expansion coefficient of the imaging lens 100 is αL, and the temperature change is ΔT, since the imaging system 10 has an extremely small imaging magnification, the image interval change amount ΔZ is The difference between the elongation and the elongation of the solid-state imaging device can be expressed by equation (4).

ΔZ = 1.68 × (αL−αS) × ΔT (4) where αS = 0.26 × 10 ⁻⁵ , ΔT = 20 [°],
Further, assuming that the taking lens 100 is made of low melting point glass and αL = 1.2 × 10 ⁻⁵ , ΔZ is 0.000
It is calculated as 32 [mm]. This is the amount of change in the distance between the G object image and the R object image, and the amount of change in the distance between the R object image and the B object image.

Considering the B object image as a change with respect to the G object image as the reference image signal, since the image interval is 1.68 × 2, the image interval change amount is ΔZ × 2 = 0.0063.
[Mm]. This image interval is set to A. If the operating temperature range of the camera is 0 to 40 °, the reference temperature 2
The deviation ΔT from 0 ° is 20 °, and ΔZ
If × 2 is smaller than 画素 of the pixel pitch, there is no practical problem. Generally, the linear expansion coefficient α of the solid-state imaging device 120
Since S takes a small value of about 0.26 × 10 ^−5, it is necessary to select the linear expansion coefficient αL of the photographing lens 100 so as to satisfy Expression (5).

A × (αL−0.26 × 10 ⁻⁵ ) × 20 <1/2 · P (5) where A is an image interval and P is a pixel pitch.

Since the linear expansion coefficient αL = 1.2 × 10 ⁻⁵ of the photographic lens 100 used previously satisfies the relationship of the equation (5), it can be said that it is a suitable material for this camera.

In addition to the change in the image interval due to the change in the object distance or the temperature, the image pickup areas 120a, 120a,
0b and 120c are shifted by 1/2 pixel from each other,
A technique of pixel shifting to increase the resolution with a small number of pixels is used. The 1/2 pixel shift amount is set for a virtual subject distance of 2 m.

As shown in FIG. 15, the imaging area 120b for outputting the R image and the imaging area 120c for outputting the B image are shifted by 1/2 pixel in the horizontal and vertical directions with respect to the imaging area 120a for the G image signal. It is arranged.

This pixel shift can be realized by slightly decentering the lens portions 100b and 100c of the photographing lens 100 with respect to the lens portion 100a.
This may be realized by slightly decentering the 0 imaging regions 120b and 120c with respect to the imaging region 120a.

In an optical filter array such as a Bayer array, for example, a pixel having a red optical filter or a pixel having a blue optical filter enters between pixels having a green optical filter, so that aliasing distortion occurs. An optical low-pass filter to suppress is needed. However, if such a configuration is adopted in which images having different spectral distributions are captured for each imaging region, pixels having respective optical filters can be densely arranged, and as a result, the influence of aliasing is small and an optical low-pass filter can be used. A high-definition image can be obtained without the need. Therefore, it is possible to reduce the size of the imaging system and to significantly reduce the cost.

Next, the signal processing will be described.

As described above, the solid-state imaging device 120 is effectively applied to an imaging device having 1800 pixels in the long side direction and 800 pixels in the short side direction, each having a total of 1.440,000 pixels, and a red color on the front surface thereof. Optical filters of three primary colors of (R), green (G), and blue (B) are arranged for each predetermined region.

As shown in FIG. 14, the solid-state imaging device 120
Image signals read from the A / D converter 5
00 to the image processing system 20. The A / D converter 500 is, for example, a signal conversion circuit that converts and outputs a 10-bit digital signal corresponding to the amplitude of the signal of each exposed pixel, for example, and performs subsequent image signal processing by digital processing. Be executed.

The image processing system 20 is a signal processing circuit for obtaining an image signal of a desired format from the R, G, B digital signals, and converts the R, G, B color signals into a luminance signal Y and a color difference signal (R−G). Y) and (B-Y).

The RGB image processing circuit 210 receives the signal 180 from the solid-state imaging device 120 via the A / D converter 500.
A signal processing circuit for processing an image signal of 0 × 800 pixels, which includes a white balance circuit, a gamma correction circuit, and an interpolation operation circuit for increasing the resolution by interpolation operation.

The YC processing circuit 230 is a signal processing circuit that generates a luminance signal Y and color difference signals RY and BY. A high-frequency luminance signal generating circuit for generating the high-frequency luminance signal YH, a low-frequency luminance signal generating circuit for generating the low-frequency luminance signal YL, and a color difference signal generating circuit for generating the color difference signals RY and BY. Have been. The luminance signal Y is formed by combining the high-frequency luminance signal YH and the low-frequency luminance signal YL.

The details of the RGB image processing circuit 210 will be described.

The RGB signals output for each of the R, G, and B regions via the A / D converter 500 are first subjected to a predetermined white balance adjustment in a white balance circuit in the RGB image processing circuit 210. Further, a predetermined gamma correction is performed by a gamma correction circuit.

The interpolation operation circuit in the RGB image processing circuit 210 generates an image signal having a resolution four times as large as 600 × 800 pixels by interpolation processing, and converts the image signal from the solid-state image pickup device 120 into a high definition image signal. Then, the signal is supplied to the subsequent high-frequency luminance signal generation circuit, low-frequency luminance signal generation circuit, and color difference signal generation circuit.

The size of each of the RGB object images is determined by the photographing lens 10.
Since the values are already the same by setting 0, first, a calculation process for correcting the distortion of the photographing optical system is performed on each image signal by a known method. Subsequent interpolation processing, luminance signal processing, and color difference signal processing conform to the processing in a normal digital color camera. The interpolation process is as follows.

First, the image pickup area 120 which is the reference image signal
The G image signal from a is interpolated by the following equations (6) to (9).

G2i2j = Gij (6) G2i (2j + 1) = Gij · 1/2 + Gi (j + 1) · 1/2 (7) G (2i + 1) 2j = Gij · 1/2 + G (i +1) j · 1/2 (8) G (2i + 1) (2j + 1) = Gij · 1/4 + Gi (j + 1) · 1/4 + G (i + 1) j · 1 / 4 + G (i + 1) 0 + 1) ・ (9) As a result, as shown in FIG. 16, 16 G pixels are generated from the 4 G pixels, respectively, and 600 G from the imaging region 120a are generated. A G image signal of × 800 pixels is 1200 × 16
It is converted to 00 pixels.

Next, the R pixel output from the image pickup area 120b corresponding to each position of the G image signal obtained by the above equations (6) to (9) is calculated by the following equations (10) to (13). Perform interpolation.

R2i2j = R (i−1) (j−1) · 1/4 + R (i−1) j · 1/4 + Ri (j−1) · 1/4 + Rij · 1/4 (10) R2i (2j +1) = R (i-1) j ・ 1/2 + Rij1 / 21/2 (11) R (2i + 1) 2j = Ri (j-1) 1/2 + Rij ・ 1/2 (12) R (2i + 1) (2j + 1) = Rij (13) As described above, the imaging region of the R object image and the imaging region of the B object image are shifted by 1/2 pixel from the imaging region of the G object image. Because of the arrangement, the original output of the address ij is applied to the addresses (2i + 1) and (2j + 1) as in equation (13).

Similarly, similarly to the R pixel, the image pickup area 120c
The following formulas (14) to (17) correspond to the respective positions of the G image signal obtained by the above formulas (6) to (9).
Performs interpolation calculation in.

B2i2j = B (i-1) (j-1) ・ 1/4 + B (i-1) j ・ 1/4 + Bi (j-1) ・ 1/4 + Bij ・ 1/4 (14) B2i (2j +1) = B (i-1) j ・ 1/2 + Bij1 / 21/2 (15) B (2i + 1) 2j = Bi (j-1) 1/2 + Bij ・ 1/2 (16) B (2i + 1) (2j + 1) = Bij (17) By the above processing, the imaging regions 120a, 120b, 12
The RGB signals of 600 × 800 pixels from 0c are converted into 1200 × 16000 pixel RGB signals of high definition image quality.

The high-frequency luminance signal generation circuit in the YC processing circuit 230 is a known signal forming circuit for forming a high-frequency luminance signal YH from a color signal having the highest spatial frequency component among the color component signals. R, G, B
From the signal containing all the color components, the luminance signal Y of the low frequency
It is a known signal forming circuit for forming L. Further, the color difference signal generating circuit converts the color difference signal R-
It is a known arithmetic circuit that calculates Y, BY.

The recording / reproducing system 30 is a processing system for outputting an image signal to a memory and outputting an image signal to the liquid crystal monitor 4, and is a recording processing circuit for performing a process of writing and reading an image signal to and from the memory. 300, and a reproduction processing circuit 310 that reproduces an image signal read from the memory and outputs the image signal to a monitor output. More specifically, the recording processing circuit 30
0 includes a compression / expansion circuit that compresses a YC signal representing a still image and a moving image in a predetermined compression format, and expands the compressed data when it is read. The compression / expansion circuit includes a frame memory for signal processing and the like, and accumulates the YC signal from the image processing system 20 for each frame in this frame memory, reads out each of a plurality of blocks, and performs compression encoding. The compression encoding is performed, for example, by performing two-dimensional orthogonal transformation, normalization, and Huffman encoding on an image signal for each block.

The reproduction processing circuit 310 is a circuit that converts the luminance signal Y and the color difference signals RY and BY into a matrix and converts them into, for example, RGB signals. Reproduction processing circuit 31
The signal converted by 0 is output to the liquid crystal monitor 4,
The visible image is displayed and reproduced.

On the other hand, the control system 40 includes control circuits of respective units for controlling the imaging system 10, the image processing system 20, and the recording / reproducing system 30 in conjunction with an external operation. It controls driving of the solid-state imaging device 120, operation of the RGB image processing circuit 210, compression processing of the recording processing circuit 300, and the like. Specifically, an operation detection circuit 410 that detects an operation of the release button 6, a system control unit 400 that controls each unit in conjunction with the detection signal, and generates and outputs a timing signal and the like at the time of imaging, A solid-state image sensor drive circuit 420 that generates a drive signal for driving the solid-state image sensor 120 under the control of the system controller 400.

Next, the operation of the imaging apparatus according to the present embodiment will be described.

First, when the main switch 5 is turned on,
A power supply voltage is supplied to each unit, and the unit is operable. Next, it is determined whether or not an image signal can be recorded in the memory.
At this time, the number of recordable images is displayed on the remaining number display 13 of the liquid crystal monitor 4 according to the remaining capacity. The operator who sees the display turns the camera toward the object field and presses the release button 6 if shooting is possible.

When the release button 6 is pressed halfway down,
Exposure time is calculated. When all shooting preparation processing is completed, shooting becomes possible, and the display is reported to the photographer. Thus, when the release button 6 is pressed to the end, the operation detection circuit 410 causes the system control circuit 40
The detection signal is transmitted to 0. At this time, the elapsed time of the exposure time calculated in advance is counted, and when the predetermined exposure time has elapsed, a timing signal is supplied to the drive circuit 420. Thus, the drive circuit 420 generates horizontal and vertical drive signals and exposes 1600 × 800
Each of the pixels is sequentially read out in the horizontal and vertical directions.

Each pixel read out is converted into a digital signal of a predetermined bit value by the A / D converter 500, and is sequentially supplied to the RGB image processing circuit 210 of the image processing system 20. The RGB image processing circuit 210 performs an interpolation process to quadruple the pixel resolution in a state where these have been subjected to white balance and gamma correction, respectively.
It is supplied to the C processing circuit 230.

In the YC processing circuit 230, the high-frequency luminance signal generation circuit generates the high-frequency luminance signal YH for each of the RGB pixels, and similarly, the low-frequency luminance signal generation circuit generates the low-frequency luminance signal YL. Each is calculated. The calculated high-frequency luminance signal YH is output to the adder via the low-pass filter. Similarly, the low-frequency luminance signal YL is subtracted from the high-frequency luminance signal YH and output to the adder through a low-pass filter. Thereby, the difference YL-YH between the high-frequency luminance signal YH and the low-frequency luminance signal is added, and the luminance signal Y is obtained. Similarly, in the color difference signal generation circuit, the color difference signal R
-Y and BY are obtained and output. The output color difference signal R
The components -Y and BY that have passed through the low-pass filter are supplied to the recording processing circuit 300.

Next, the recording processing circuit 30 receiving the YC signal
0 is the respective luminance signal Y and color difference signals RY, B
−Y is compressed by a predetermined still image compression method, and is sequentially recorded in the memory.

When each image is reproduced from an image signal representing a still image or a moving image recorded in the memory, when the reproduction button 9 is pressed, the operation is detected by the operation detecting circuit 410, and the system control unit The detection signal is supplied to 400. Thereby, the recording processing circuit 300 is driven. The driven recording processing circuit 300 reads the recorded content from the memory and displays an image on the liquid crystal monitor 4. The operator selects a desired image by pressing a selection button or the like.

(Second Embodiment) The first embodiment is
An imaging system according to a second embodiment in which the positional relationship between the imaging lens and the imaging area is different will be described.

FIG. 20 is a detailed diagram of the image pickup system 890. First, the stop 810 has four circular openings 8 as shown in FIG.
10a, 810b, 810c, and 810d, from each of which the object light incident on the light incident surface 800e of the photographing lens 800 passes through four lens units 800 of the photographing lens 800.
a, 800b, 800c, and 800d to form four object images on the imaging surface of the solid-state imaging device 820. Aperture 110, light incident surface 800e, and solid-state imaging device 820
Are arranged in parallel. Here, the light incident surface 800e of the photographing lens 800 is a plane, but may be formed of four spherical surfaces or four rotationally symmetric aspheric surfaces.

Four lens units 800a, 800b, 80
Reference numerals 0c and 800d denote infrared cut filters having a spherical portion having a circular diameter as shown in FIG. 22 when the photographing lens 800 is viewed from the light exit side, and having a low transmittance in a wavelength region of 670 nm or more in the spherical portion. However, a light-shielding film is formed on the flat portion 800f indicated by hatching. That is, the photographing optical system is composed of the photographing lens 800 and the aperture 8.
10, four lens units 800a, 800b, 8
Each of 00c and 800d is an imaging system.

FIG. 24 is a front view of the solid-state imaging device 820.
Four imaging regions 8 corresponding to the four object images to be formed
20a, 820b, 820c, and 820d.
Each of the imaging regions 820a, 820b, 820c, and 820d includes a pixel having a vertical and horizontal pitch of 2.8 μm,
It is an area of 2.24 mm x 1.68 mm formed by arranging 0 pieces, and the dimensions of the entire imaging area are 4.78 mm x 3.36 including the 0.3 mm of the separation band of the imaging area at the center.
mm, and the diagonal dimension of each imaging region is 2.80 mm. In the figure, 851a, 851b, 851c, 85
1d is an image circle in which an object image is formed. Image circles 851a, 851b, 851c,
The shape of 851d is a circle determined by the size of the aperture of the stop and the spherical portion on the exit side of the photographing lens 800, and the image circles 851a, 851b, 851c, and 851d have overlapping portions.

Returning to FIG. 20, a portion 852 shown by hatching of a region between the diaphragm 810 and the photographing lens 800 is shown.
Reference numerals a and 852b denote optical filters formed on the light incident surface 800e of the photographing lens 800. Shooting lens 800
21, the optical filters 852a, 852b, 852c, 852d are formed in a range completely including the aperture openings 810a, 810b, 810c, 810d.

The optical filters 852a and 852d are shown in FIG.
The optical filter 852b has a spectral transmittance characteristic of transmitting mainly red light indicated by R, and the optical filter 852c has a spectral transmittance characteristic of transmitting mainly red light indicated by R. It mainly has a spectral transmittance characteristic of transmitting blue light. That is, these are primary color filters. Lens parts 800a, 800b, 800c, 800
As the product of the characteristics of the infrared cut filter formed on the image circle 85d, the object images formed on the image circles 851a and 851d are green light components,
The object image formed on the image circle 1b has a red light component, and the object image formed on the image circle 851c has a blue light component.

On the other hand, the optical filters 853a, 853b, 853c, 853 are also provided on the four image pickup areas 820a, 820b, 820c, 820d of the solid-state image pickup device 820.
d are formed, and their spectral transmittance characteristics are also equivalent to those shown in FIG. That is, the imaging areas 820a and 820a
20d is for green light (G), imaging area 820b is for red light (R), and imaging area 820c is blue light (B).
Has sensitivity to

Since the light receiving spectrum distribution of each imaging region is given as the product of the pupil and the spectral transmittance of the imaging region, the combination of the pupil and the imaging region is selected according to the wavelength range. That is, the object light that has passed through the aperture 810a of the aperture is mainly photoelectrically converted in the imaging area 820a, the object light that has passed through the aperture 810b of the aperture is mainly photoelectrically converted in the imaging area 820b, and the object that has passed through the aperture 810c of the aperture. Light is mainly emitted from the imaging area 82.
The object light which is photoelectrically converted at 0c and further passes through the aperture 810d of the stop is photoelectrically converted mainly at the imaging region 820d. That is, the imaging regions 820a and 820d output a G image, the imaging region 820b outputs an R image, and the imaging region 820c outputs a B image. As described above, by using multiple optical filters for color separation in the pupil of the imaging optical system and the imaging device, the color purity can be increased.

The separation band between the image pickup areas corresponds to the image pickup area 82.
Since both 0a and 820d have obtained the G image signal, the overlap of the image circles is prevented during this time.

In the image processing system 20, a plurality of imaging regions of the solid-state imaging device 820 each form a color image based on a selective photoelectric conversion output obtained from one of the plurality of images. At this time, since the peak wavelength of the relative luminous efficiency is 555 nm, signal processing is performed based on the G image signal including this wavelength. The G object image has two imaging regions 820a and 820d
Therefore, the number of pixels is twice as large as that of the R image signal and the B image signal, so that a particularly high-definition image can be obtained in a wavelength region having high visibility.

At this time, apart from the fluctuation of the image interval due to a change in the object distance and the temperature, which will be described later, the image pickup areas 820a and 820d of the solid-state image pickup device are shifted by half a pixel up, down, left, and right to reduce the number of pixels. A technique of shifting the pixel to increase the resolution is used. The 1/2 pixel shift amount is set for a virtual subject distance of 2 m.

Even if this pixel shift is realized by slightly decentering the lens portion 800d of the photographing lens 800 with respect to the lens portion 800a, the imaging region 820d of the solid-state image sensor 820 is slightly shifted with respect to the imaging region 820a. It may be realized by eccentricity.

Since the imaging system has four lens units,
The positions of the four object images relatively change according to the subject distance. As described above, each imaging area is 2.24 mm × 1.6.
8 mm, and two of them are arranged adjacent to each other so that the long sides are in contact with each other.
Are separated by a separator. Therefore, the center interval between adjacent imaging regions is 1.68 mm in the vertical direction and 2.54 mm in the horizontal direction. The farthest imaging areas are imaging areas 820a and 820d located diagonally, and
The imaging areas are 820b and 820c, and this distance is 3.045 mm.

The YC processing circuit 230, which will be described later, performs signal processing on the assumption that the center of the object image matches the center of the imaging area. Paying attention to the imaging areas 820a and 820d,
Assuming that an object image at a virtual subject distance of 2 m is formed on the imaging unit at 3.045 mm, which is the same as the imaging area interval, FIG.
As shown in FIG.
The interval of 00d is set to 3.0420 mm. In the figure, arrows 855a and 855d denote symbols representing an imaging system having positive power by the lens units 800a and 800d of the photographing lens 800, rectangles 856a and 856d denote symbols representing ranges of the imaging regions 820a and 820d, and L80.
1, L802 is the optical axis of the imaging system 855a, 855d. Since the light-incident surface 800e of the photographing lens 800 is a flat surface and the lens portions 800a and 800d, which are light-exit surfaces, are spherical, a straight line passing through each sphere and perpendicular to the light-incident surface is the optical axis.

At this time, since the images of the object at infinity are formed at the same interval as the lens units 800a and 800d as shown in FIG. 26, the interval between the G object images is 3.0420 mm. Therefore, the center interval of the imaging region is 3.045 mm
This difference ΔY is 0.0030 mm, that is, 3.0 μm. Such a change in the interval between the G object images appears as a decrease in resolution.

Further, focusing on the image pickup areas 820b and 820c, ΔY is also 3.0 μm, and a color shift occurs at an object at infinity by this dimension. Therefore, two problems, that is, a change in the distance between the G object images and a deviation between the R object image and the B object image must be considered.

However, since the relative luminous efficiency of the G object image is high and a slight decrease in resolution can be recognized, first,
Paying attention to the change in the interval between the G object images, if this is an acceptable level, it can be said that the deviation between the R object image and the B object image does not matter.

In general, a short-distance object such as a person is located at the center of the photographing screen, and a long-distance object is often located around the screen. In addition, the aberration of the photographing lens increases around the screen. Therefore, if the maximum image interval change between the G object images is smaller than twice the pixel pitch, there is no practical problem. Since the pixel pitch P of the solid-state imaging device 820 is 2.8 μm, ΔY <2 × P, and it can be seen that such a change in the image interval of the infinite image is at an acceptable level.

Therefore, the deviation between the R object image and the B object image is also at an acceptable level, and it can be determined that this imaging system has practically sufficient performance.

(Third Embodiment) FIG. 27 shows a third embodiment of the image pickup system.
FIG. 2 is a cross-sectional view showing the embodiment. Aperture 1 of imaging system 890
10. The taking lens 100 is the same as in the first embodiment.

FIG. 28 is a front view of the solid-state imaging device 820. Image circles 51a, 51b, and 51 are formed on the solid-state imaging device 820 in the same manner as in the first embodiment shown in FIG.
c is formed, and the image circles 51a and 51b and the image circles 51b and 51c have overlapping portions.

Unlike the first embodiment, the imaging area 8
The microlens 8 is placed on top of 20a, 820b and 820c.
Reference numeral 21 is formed for each light receiving section (for example, 822a and 822b) of each pixel. Instead, an optical filter that transmits green, red, and blue is not formed in the solid-state imaging device 820. Note that, for description of the microlens, the pixel shift between the imaging regions is omitted.

The micro lens 821 is a solid-state image sensor 82
The eccentric arrangement is set with respect to the zero light receiving unit, and the amount of eccentricity is set to zero at the center of each of the imaging regions 820a, 820b, and 820c, and to increase toward the periphery.
Further, the eccentric direction is determined in each of the imaging regions 820a, 820b, 82
0c is the direction of the line segment connecting the center point and each light receiving section.

FIG. 29 is a diagram for explaining the operation of the microlens, and includes an image pickup area 820a and an image pickup area 820b.
FIG. 11 is an enlarged cross-sectional view of light receiving portions 822a and 822b at positions where the light receiving portions contact. The micro lens 821a is decentered upward in the figure with respect to the light receiving unit 822a.
The micro lens 821b is eccentric to the lower side of FIG. As a result, the light beam incident on the light receiving section 822a is limited to the area indicated by hatching as 823a, and the light beam incident on the light receiving section 822b is limited to the area indicated by hatching as 823b.

The directions of inclination of the light flux regions 823a and 823b are opposite to each other.
Heading to Therefore, if the amount of eccentricity of the microlens is appropriately selected, only a light beam emitted from a specific pupil enters each imaging region. That is, the aperture 11 of the diaphragm
Object light that has passed through the aperture 0a is mainly photoelectrically converted in the imaging area 820a, object light that has passed through the aperture 110b of the aperture is mainly photoelectrically converted in the imaging area 820b, and
The amount of eccentricity can be set so that the object light that has passed through 10c is photoelectrically converted mainly in the imaging region 820c. Since an optical filter is provided on the solid-state imaging device 820, that is, the imaging region 820a outputs a G image, the imaging region 820b outputs an R image, and the imaging region 820c outputs a B image.

Assuming that the pixel pitch of the solid-state imaging device is fixed, an RGB color filter having a set of, for example, 2 × 2 pixels is formed on the solid-state imaging device to impart wavelength selectivity to each of the pixels. This reduces the size of the object image to 1 / √3 as compared with the method used in a general digital color camera that separates an object image into RGB images. The focal length is approximately 1 /
$ 3. Therefore, it is extremely advantageous for reducing the thickness of the camera.

Furthermore, in the first embodiment in which an image is selectively photoelectrically converted based on the spectrum of an object image, complementary color optical filters of cyan, magenta, and yellow having a wide overlapping wavelength range can be used. However, if the image is selectively photoelectrically converted by the eccentricity of the microlens as described above, the overlapping of the wavelength ranges becomes irrelevant and a complementary color optical filter can be used. When the complementary color optical filter is used, the amount of light reaching the solid-state imaging device can be increased as compared with the primary color filter.

When an image is selected based on the eccentricity of the microlens, an optical filter may be provided on the solid-state image sensor 820 instead of providing the optical filter on the light incident surface 100d of the taking lens 100. Irrespective of the arrangement of the optical filter, it is extremely advantageous in terms of light quantity as compared with the photographing optical path in which the optical filter of the first embodiment is passed twice or the photographing optical path using the polarizing plate of the second embodiment. Moreover,
Light incident surface 100e of photographing lens 100 and solid-state image sensor 8
It is also possible to further reduce the crosstalk of the image by providing both on the top 20.

[0130]

Further, another object of the present invention is to supply a storage medium (or a recording medium) on which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or an apparatus, and to provide the system or the apparatus. It is needless to say that the present invention can also be achieved by a computer (or CPU or MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. When the computer executes the readout program codes, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instructions of the program codes. It goes without saying that a case where some or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing is also included.

Further, after the program code read from the storage medium is written into the memory provided in the function expansion card inserted into the computer or the function expansion unit connected to the computer, the program code is read based on the instruction of the program code. , The CPU provided in the function expansion card or the function expansion unit performs part or all of the actual processing,
It goes without saying that a case where the functions of the above-described embodiments are realized by the processing is also included.

As described above, a plurality of openings for taking in external light from different positions, the external light taken in from the plurality of openings are separately received, and a predetermined number of external light are received for each of the separately received external light. The following effects were obtained by an imaging apparatus having a plurality of imaging means for extracting color components.

(1) Since no re-imaging system is required, an imaging optical system having a short optical path length can be obtained.

(2) Since it is easy to equalize the distortion of the images of each color, an extremely simple optical configuration such as a three-lens or four-lens single-lens optical system could be obtained.

(3) Since each imaging system has a narrow wavelength range, chromatic aberration hardly occurs, and there is no need to combine a plurality of lenses for achromatism.

(4) In addition, since the center of the imaging region and the optical axis of each imaging system are substantially coincident with each other, no asymmetrical optical aberration occurs, and high sharpness can be obtained in the synthesized color image. Was completed.

(5) As a result, a thin imaging device suitable for a card-type digital color camera can be realized. Since the photographing optical axis can be set in the thickness direction of the card, the viewing direction of the color LCD monitor 4 and the viewfinder eyepiece window 11 can be set.
The observation direction can be made to coincide with the photographing optical axis, which is very preferable in terms of camera operability.

[0138]

As described above, according to the present invention,
A color image with high sharpness can be obtained using a simple configuration and an imaging optical system having a short optical path length.

[Brief description of the drawings]

FIG. 1 is a sectional view of an imaging system.

FIG. 2 is a front view of the solid-state imaging device.

FIG. 3 is a plan view of a diaphragm.

FIG. 4 is a diagram illustrating a formation range of an optical filter.

FIG. 5 is a view of the photographing lens as viewed from a light exit side.

FIG. 6 is a diagram illustrating a spectral transmittance characteristic of an optical filter.

FIG. 7 is a diagram illustrating a spectral transmittance characteristic of a color purity correction filter.

FIG. 8 is a diagram showing a spectral transmittance characteristic of the photochromic glass.

FIG. 9 is a diagram illustrating a transmittance distribution of a transmittance distribution type filter.

FIG. 10 is a diagram illustrating OTF characteristics of a photographing lens.

FIG. 11 is a diagram illustrating a luminance distribution of a point image.

FIG. 12 is a diagram for explaining setting of the distance between lens units.

FIG. 13 is a diagram for explaining the position of an image of an object at infinity.

FIG. 14 is a block diagram of a signal processing system.

FIG. 15 is a diagram illustrating a positional relationship between an imaging region for an R pixel and an imaging region for a B pixel with respect to an imaging region for a G image.

FIG. 16 is an explanatory diagram of an interpolation process.

FIG. 17 is a front view of the digital color camera.

FIG. 18 is a rear view of the digital color camera.

19 is a cross-sectional view at the position of arrow A in FIG.

FIG. 20 is a detailed diagram of an imaging system.

FIG. 21 is a diagram of the photographing lens viewed from the light incident side.

FIG. 22 is a view of the taking lens as viewed from a light exit side.

FIG. 23 is a plan view of the stop.

FIG. 24 is a front view of the solid-state imaging device.

FIG. 25 is a diagram for explaining setting of the distance between lens units.

FIG. 26 is a diagram for explaining the position of an image of an object at infinity.

FIG. 27 is a sectional view of an imaging system according to the third embodiment.

FIG. 28 is a front view of the solid-state imaging device according to the third embodiment.

FIG. 29 is a diagram illustrating the operation of a microlens.

[Explanation of symbols]

1 Camera body 51a, 51b, 51c Image circle 52a, 52b, 52c Optical filters 53a, 53b, 53c formed on photographing lens Optical filters 54a, 54b, 54c formed on solid-state imaging device Transmittance distribution type filter 100 Photographing lenses 100a, 100b, 100c Lens part of photographing lens 110 Aperture 120 Solid-state image sensor

Claims (10)

[Claims] 1. A plurality of openings for taking in external light from different positions, and separately receiving external light taken in from the plurality of openings, and extracting a predetermined color component for each of the separately received external light. An imaging device comprising: 2. The image pickup apparatus according to claim 1, wherein the plurality of image pickup units include a plurality of optical systems for forming an image of the external light taken in from the opening. 3. The imaging apparatus according to claim 2, wherein each of the plurality of optical systems includes a single lens. 4. The plurality of optical systems are three optical systems, and three single lenses corresponding to the three optical systems respectively include an optical filter that transmits red light and a green filter that transmits green light. The imaging device according to claim 3, further comprising an optical filter and an optical filter that transmits blue light. 5. The imaging apparatus according to claim 3, wherein the plurality of single lenses constituting the plurality of optical systems are integrally formed by molding a glass material or a resin material. 6. The imaging apparatus according to claim 5, wherein a light-shielding film is formed at a portion between the plurality of single lenses in a molded body obtained by integrally molding the plurality of single lenses. . 7. The imaging device according to claim 3, wherein the plurality of single lenses include an infrared cut filter. 8. The imaging apparatus according to claim 1, wherein the plurality of imaging units include one imaging device having a plurality of imaging regions corresponding to each of the plurality of openings. 9. The plurality of imaging regions are three imaging regions, each of which includes an optical filter that transmits red light, an optical filter that transmits green light, and a blue filter that transmits blue light. The imaging device according to claim 8, further comprising an optical filter that causes the light to be filtered. 10. The imaging apparatus according to claim 1, wherein the plurality of imaging units include a plurality of diaphragms corresponding to the plurality of apertures.