JP2003060993A - Imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging system with an imaging means having superior sensitivity and smear resistance which are in conflict to each other. SOLUTION: An imaging section 4 is configured by arranging solid-state imaging devices 8, 10, 12, 14, having different imaging characteristics on a semiconductor substrate 6 in a matrix form, and an optical distributor 22 comprises spectral prisms 24, 26, 28. The solid-state imaging devices 8, 10, 12 respectively have normal sensitivity and smear resistance, high sensitivity and superior smear resistance, and the solid-state imaging device 14 excludes color filters to have sensitivity higher than that of the solid-state imaging device 10. The spectral prisms 24, 26, 28 split the light which is made incident from an object through a lens 30 into the light traveled straight in the forward direction and the refracted light, and they are respectively made incident onto each solid-state imaging device. Each solid-state imaging device converts the incident light into an electrical signal and outputs an imaged signal with different characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup system including a solid-state image pickup device.

[0002]

2. Description of the Related Art Solid-state image pickup devices include those using charge-coupled devices and CMOS image sensors, which are widely used as image pickup means in digital still cameras, digital video cameras, portable terminal devices and the like. Sensitivity and smear characteristics are characteristics that greatly affect the performance of the solid-state imaging device. The sensitivity and smear characteristics of the solid-state image pickup device are, of course, both excellent, but these are contradictory characteristics. For example, if the sensitivity is increased, the smear characteristic is lowered, and conversely, if the smear characteristic is increased, the sensitivity is reduced. Will fall. This will be described in detail.

11A to 11C are partially enlarged plan views showing a part of a solid-state image pickup device having a CCD structure. The most common interline CCD solid-state imaging device 10
2, a large number of optical sensors 104 are arranged in a matrix on a semiconductor substrate, as shown in FIG.
A vertical charge transfer register 106 is provided for each column of each photosensor 104, and a horizontal charge transfer register (not shown) is provided on one end side of the vertical charge transfer register 106. Note that FIG. 11 shows only a part of the solid-state imaging device, the photosensors 104 are arranged in the vertical direction (row direction) on the paper surface, and the vertical charge transfer registers 106 extend in the vertical direction on the paper surface. There is.

In such a structure, each optical sensor 1
The signal charge generated by the light received by 04 is supplied to the adjacent vertical charge transfer register 106, and is transferred to the horizontal charge transfer register (not shown) on the vertical charge transfer register 106. The signal charge reaching the horizontal charge transfer register is transferred on the horizontal charge transfer register in a direction orthogonal to the transfer direction by the vertical charge transfer register 106, and then converted into a voltage signal and output as an image signal.

Further, as shown in FIG. 11, a light shielding film 108 for preventing unnecessary light from entering the optical sensor 104 is formed on the semiconductor substrate, and the opening 11 thereof is formed.
Through 0, light from the subject enters the respective photosensors 104. Therefore, each optical sensor 1
The amount of light incident on 04 is determined by the opening 110 of the light shielding film 108.
It depends on the area of.

FIG. 11A shows a case where the area of the opening 110 of the light shielding film 108 is generally larger than the area of the light receiving surface of the optical sensor 104. On the other hand, FIG. 11B shows the opening 110 of the light shielding film 108.
The case where the area of the opening 110 is widened is shown.
Since the amount of light incident on the optical sensor 104 is increased by increasing the width, the sensitivity of the solid-state imaging device 1 is improved. On the other hand, FIG. 11C shows a case where the area of the opening 110 of the light shielding film 108 is narrowed. By narrowing the opening 110 in this manner, the amount of light incident on the optical sensor 104 is reduced, and thus the solid state is reduced. Although the sensitivity of the image pickup apparatus 1 is reduced, the smear characteristic is improved.

As described above, the sensitivity and smear characteristic of the solid-state image pickup device are determined by the size of the opening 110 of the light shielding film 108. The wider the opening 110, the higher the sensitivity but the worse the smear characteristic. Conversely, the narrower the opening 110, the lower the sensitivity, but the better the smear characteristic.
Therefore, conventionally, the opening 110 is formed to have a width as shown in FIG. 11 (A) in consideration of smear characteristics while ensuring a certain sensitivity.

[0008]

However, as a result, in the conventional solid-state image pickup device, it is possible to obtain a photographed image with well-balanced sensitivity and smear characteristics, but a clear image is obtained when the subject is particularly dark. However, there is a problem in that smear appears strongly when the subject is not bright, or when there are very bright luminescent spots in the subject.

The present invention has been made in order to solve such a problem, and an object thereof is to provide an imaging system excellent in both contradictory characteristics such as sensitivity and smear characteristics.

[0010]

In order to achieve the above object, the present invention provides an image pickup system comprising a solid-state image pickup device which receives light from a subject and generates an electric signal representing an image of the subject. A plurality of solid-state image pickup devices that are arranged close to each other and have different image pickup characteristics, and a light distribution device that makes light from the same subject incident on each of the solid-state image pickup devices simultaneously or sequentially. And

As described above, the image pickup system of the present invention is provided with a plurality of solid-state image pickup devices having different image pickup characteristics, and light from the same subject is made incident on each of the solid-state image pickup devices by the light distribution device for photographing. Since it can be carried out, for example, one solid-state imaging device as a high-sensitivity solid-state imaging device,
If another one of the solid-state image pickup devices has an excellent smear characteristic, it is possible to take an image of a subject with high sensitivity and at the same time obtain a taken image having an excellent smear characteristic.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view showing an example of an image pickup system according to the present invention, and FIG. 2 is a schematic plan view showing an image pickup section constituting the image pickup system of FIG. As shown in FIG. 2, the image pickup unit 4 included in the image pickup system 2 shown in FIG. 1 has four CCD structure solid-state image pickup devices 8 arranged in a matrix on the same semiconductor substrate 6 in close proximity to each other. Includes 10, 12, and 14. Solid-state imaging device 8
Has normal sensitivity and smear characteristics, and the solid-state imaging device 1
0 has a wide opening (see FIG. 11) of the light-shielding film and has higher sensitivity than other solid-state imaging devices. In addition, the solid-state imaging device 1
2 has a narrow opening in the light-shielding film and is superior in smear characteristics to other solid-state imaging devices, and the solid-state imaging device 14 has basically the same structure as the solid-state imaging device 10, but unlike other solid-state imaging devices. There is no color filter on the light sensor, so black and white photography is performed. Therefore, the solid-state imaging device 14 has the highest sensitivity. The surface of the semiconductor substrate 6 other than the solid-state imaging devices 8, 10, 12, and 14 is covered with a light shielding film 16.

FIG. 3 is a schematic plan view showing the image pickup section 4 of FIG. 1 including a horizontal charge transfer register formed for each solid-state image pickup device. As shown in FIG. 3, in the present embodiment, a horizontal charge transfer register 18 is formed for each solid-state imaging device 8, 10, 12, 14, and a vertical charge transfer register (not shown) of each solid-state imaging device. The signal charge 20 transferred in the vertical direction is transferred in the horizontal direction by the horizontal charge transfer register 18 and finally output as an image signal for each solid-state imaging device.

The light distribution device 22 shown in FIG. 1 is composed of spectral prisms 24, 26 and 28, and a lens 30 for focusing light from a subject on each solid-state image pickup device and the solid-state image pickup devices 8 and 10. , 12 and 14 are arranged. The spectroscopic prism 24 transmits the light 32 that has passed through the lens 30.
Is divided into light that travels straight and light that bends in the direction of the back surface of the paper. The spectroscopic prisms 26 and 28 are arranged in a state of being overlapped with each other when viewed from the side surface, and the light that has proceeded straight in the spectroscopic prism 24 enters the spectroscopic prism 26, advances straight in the spectroscopic prism 26, and enters the solid-state imaging device 14. The light is split into light and light that is bent upward by the spectral prism 26 and enters the solid-state imaging device 10. On the other hand, the light bent by the spectral prism 24 enters the spectral prism 28 and
It is split into light that travels straight inside and enters the solid-state imaging device 12, and light that is bent upward by the spectral prism 26 and enters the solid-state imaging device 8.

Light from each of the spectral prisms 26 and 28 is transmitted to each of the solid-state image pickup devices 8 and 1 as indicated by a circle 34 in FIG.
It is incident on 0, 12, and 14, and is converted into an electric signal by each solid-state imaging device. Here, the interval between the solid-state imaging devices is set to an interval such that light to one solid-state imaging device does not enter another solid-state imaging device.

The image signal 36 (FIG. 1) representing the photographing result output from each solid-state image pickup device is input to the image processing device 38. Based on the image signal 36 from each solid-state image pickup device, the image processing device 38 synthesizes the images taken by each solid-state image pickup device as needed, and outputs an image signal representing the result.

In the image pickup system 2 of the present embodiment configured as described above, the light from the subject is converged by the lens 30 so as to form an image on the solid-state image pickup device. After that, the light is split by the spectral prisms 24, 26, and 28 into the light beams that enter the solid-state image pickup devices 8, 10, 12, and 14, and the lights that enter the solid-state image pickup devices 8, 10, 12, and 14 are the solid-state image pickup devices. Is converted into an electric signal according to the characteristics of each solid-state imaging device.

Since the solid-state image pickup device 8 has the usual sensitivity and smear characteristics as described above, the solid-state image pickup device 8 can obtain a photographed image in which these characteristics are balanced. . Moreover, since the solid-state imaging device 10 has high sensitivity as described above,
Even if the subject is dark, a clear captured image can be obtained. On the other hand, in the solid-state imaging device 12, since the opening of the light-shielding film for each photosensor is formed narrow, an image excellent in smear characteristics can be obtained. Further, although the solid-state imaging device 14 has basically the same structure as the solid-state imaging device 10 as described above, since the color filter is not provided, the solid-state imaging device 14 is more sensitive than the solid-state imaging device 10 by about 25%. , Even darker subjects can be captured clearly. The image signal 36 from each of the solid-state imaging devices is the solid-state imaging device 8, 1
An image signal 36 that reflects the characteristics of 0, 12, and 14 is output through the image processing device 38.

Therefore, in the image pickup system 2 of the present embodiment, a well-balanced image as usual, a high-sensitivity image, an image excellent in smear characteristics, and a black-and-white image having a higher sensitivity are once obtained. Can be taken to
Images with different characteristics can be taken without missing a photo opportunity. Then, the photographer can select a photographed image that suits his or her preference.

The image processing device 38 also synthesizes the images taken by the respective solid-state image pickup devices as needed. The image combining operation of the image processing device 38 will be described by taking as an example a case where an image obtained by the solid-state imaging device 12 having excellent smear characteristics and an image obtained by the solid-state imaging device 10 having high sensitivity are combined.

FIGS. 5A to 5C are explanatory views showing the operation of the image processing device 38. 5A shows a captured image of the solid-state imaging device 12, and FIG. 5B shows a captured image of the solid-state imaging device 10. Also, FIG. 5 (C)
Indicates the result of synthesis. As shown in FIG. 5A, the solid-state imaging device 12 has excellent smear characteristics.
Even in a captured image in which the sun 42 is reflected outside the window 40, smear does not appear, or even if it appears, it becomes weak.
However, since the solid-state imaging device 12 has low sensitivity, the person 44 and the like in the room have insufficient brightness and are unclear. On the other hand, as shown in FIG. 5B, since the solid-state imaging device 10 has high sensitivity, the person 44 or the like in the room is clearly photographed. However, since the smear characteristic of the solid-state imaging device 10 is insufficient, strong smear appears at the location of the sun 42 outside the window 40 (not shown in the figure).

The image processing device 38 first identifies a bright area from the two images obtained by the solid-state image pickup devices 10 and 12. In this case, the image processing device 38
Generally specifies the area of the window 40 as a bright area.
Next, the image processing device 38 extracts the image of the identified bright region, that is, the region of the window 40 (outside the window 40) from the image captured by the solid-state imaging device 12 ((A) of FIG. 5). On the other hand, an image of a relatively dark area, that is, an area (indoor) outside the area of the window 40 is extracted from the image obtained by the solid-state imaging device 10 (FIG. 5B). Then, these two images are combined as shown in FIG. As a result, in the composite image, the person 44 and the like in the room are clear, and smear caused by the sun 42 does not pose a problem. Further, such a combination makes it possible to obtain an image in which a bright area such as the outside of a window is not crushed in white and a dark area such as a room is clear at the same time, which enables shooting with a very wide dynamic range.

Next, a second embodiment of the present invention will be described. FIG. 6 is a schematic side view showing an image pickup system as a second embodiment. The image pickup system 46 of the second embodiment differs from the image pickup system 2 of the first embodiment particularly in the configuration of the light distribution device. The image pickup unit 48 of the image pickup system 46 is configured by forming two solid-state image pickup devices 52 and 54 having different characteristics on a semiconductor substrate 50, and a light distribution device 56 is provided in each of the solid-state image pickup devices 52 and 54 of the image pickup unit 48. It is configured to allow light from the subject to enter at the same time. As the solid-state imaging devices 52 and 54, for example, a solid-state imaging device having high sensitivity and a solid-state imaging device having excellent smear characteristics can be used.

The light distribution device 56 is a solid-state image pickup device 52, 5
Wide-angle lenses 58, 60 and prisms 62, 6 for each 4
4, the light from the subject is converged by the wide-angle lenses 58 and 60 so as to form an image on the image pickup surface of the solid-state image pickup device, and the lights emitted from the wide-angle lenses are respectively associated with the corresponding prisms 62 and 62.
The optical path is bent in the direction of the corresponding solid-state imaging devices 52 and 54 by 64, and the solid-state imaging devices 52 and 54 are made incident.

Even if the light distribution device 56 is configured in this way, light from the subject can be made to enter the respective solid-state image pickup devices 52 and 54 at the same time. Therefore, the image pickup system 46 can provide high sensitivity in one shot. Both an image and an image excellent in smear characteristics can be obtained.

Next, a third embodiment of the present invention will be described. FIG. 7 is a schematic side view showing an image pickup system as the third embodiment. In the figure, the same elements as those in FIG. 6 are denoted by the same reference numerals. The imaging system 66 of the third embodiment differs from the imaging system 46 of the second embodiment in the configuration of the light distribution device. That is, the light distributor 68 includes an active prism 70 whose shape changes to change the light emission direction, and an actuator 72 which drives the active prism 70 to change the shape of the active prism 70 and switches the light emission direction. Contains.

In such a light distribution device 68, the lens 3
The light from the subject that has entered the active prism 70 through 0 changes its optical path by the active prism 70. Then, the actuator 72 drives the active prism 70 to change its shape, so that the traveling direction of the light emitted from the active prism 70 is first directed to the solid-state imaging device 52 and then to the solid-state imaging device 54. Switch. As a result, the light from the subject sequentially enters the solid-state imaging devices 52 and 54 and is converted into an electric signal. Therefore, the imaging system 6 of the third embodiment example
In No. 6 as well, it is possible to obtain both a high-sensitivity image and an image excellent in smear characteristics by one shot.

Next, a fourth embodiment of the present invention will be described. FIG. 8 is a schematic side view showing an image pickup system as a fourth embodiment. In the figure, the same elements as those in FIG. 6 are denoted by the same reference numerals. The imaging system 74 of the fourth embodiment differs from the imaging system 46 of the second embodiment in the configuration of the light distribution device. That is, the light distribution device 76 includes a mirror 78 and a mirror driving means 80, and is configured to reflect the light from the subject incident through the lens 30 by the mirror 78 and cause the light to enter the solid-state imaging devices 52 and 54. There is. Then, one or both of the angle and the position of the mirror 78 are changed by the mirror driving unit 80, and as a result, the light from the subject is sequentially switched to enter each of the solid-state imaging devices 52 and 54. Therefore, also in the image pickup system 74 of the fourth embodiment, it is possible to obtain both a high-sensitivity image and an image excellent in smear characteristics in substantially one shot.

Next, a fifth embodiment of the present invention will be described. FIG. 9 is a schematic side view showing an image pickup system as the fifth embodiment. In the figure, the same elements as those in FIG. 6 are denoted by the same reference numerals. The imaging system 82 of the fifth embodiment differs from the imaging system 46 of the second embodiment in the configuration of the light distribution device. That is, the light distribution device 84 includes the solid-state imaging device moving means 86 for moving the semiconductor substrate 50 in the direction (arrow A) orthogonal to the optical path of the incident light, and the solid-state imaging device moving means 8 is provided.
By moving the whole of the solid-state imaging devices 52 and 54 by 6, the light from the subject incident through the lens 30 is sequentially incident on the solid-state imaging devices 52 and 54. Therefore, also in the image pickup system 82 of the fifth embodiment, it is possible to obtain both a high-sensitivity image and an image excellent in smear characteristics in substantially one shot.

Although the embodiments of the present invention have been described above, needless to say, the present invention is not limited to these embodiments, and the effects can be obtained by implementing the invention in various forms. For example, in the first embodiment, the horizontal charge transfer register 18 is provided for each solid-state imaging device as shown in FIG. 3, but as shown in FIG.
1 for all solid-state imagers 8, 10, 12, 14
It is also possible to provide one horizontal charge transfer register 88. In this case, the signal charge transferred by the vertical charge transfer register of the solid-state imaging device 8 is supplied to the corresponding vertical charge transfer register of the solid-state imaging device 12 as indicated by an arrow 90, and then the horizontal charge transfer register 8 is supplied.
8 and the signal charge transferred by the vertical charge transfer register of the solid-state imaging device 10 may be supplied to the corresponding vertical charge transfer register of the solid-state imaging device 14 and sent to the horizontal charge transfer register 88.

Further, in the above-described embodiment, each solid-state image pickup device is formed on the same semiconductor chip, but
It is also possible to form each solid-state imaging device on a different semiconductor chip and arrange each semiconductor chip in close proximity. As described with reference to FIG. 4, in the first embodiment, some solid-state imaging devices are spaced from each other, but as in the third embodiment and the fourth embodiment. When light is sequentially incident on each solid-state imaging device, there is no problem even if light to be incident on a certain solid-state imaging device is incident on an adjacent solid-state imaging device. Therefore, the interval between the solid-state imaging devices should be narrowed. It is also possible.

Further, in the above second to fifth embodiments, the image pickup section has two solid-state image pickup devices.
Even when two or more solid-state image pickup devices are used, the light distribution devices of the respective embodiments have basically the same configuration and are appropriately modified so that light from a subject is incident on each solid-state image pickup device. be able to. In addition, the solid-state imaging devices 52 and 54
It is, of course, possible to input the image signal from the above to the image processing device 38 as used in the first embodiment to obtain a composite image. Further, the solid-state imaging device is not limited to the CCD structure, and a CMOS image sensor may be used.

[0033]

As described above, the present invention is an image pickup system constituted by a solid-state image pickup device which receives light from a subject and generates an electric signal representing an image of the subject, and is arranged close to each other. In addition, a plurality of solid-state image pickup devices having mutually different image pickup characteristics and a light distribution device for making light from the same subject enter the respective solid-state image pickup devices simultaneously or sequentially.

As described above, the image pickup system of the present invention is provided with a plurality of solid-state image pickup devices having different image pickup characteristics, and light from the same subject is made incident on each of the solid-state image pickup devices by the light distributor. Since it can be carried out, for example, one solid-state imaging device as a high-sensitivity solid-state imaging device,
If another one of the solid-state image pickup devices has an excellent smear characteristic, it is possible to take an image of a subject with high sensitivity and at the same time obtain a taken image having an excellent smear characteristic.

[Brief description of drawings]

FIG. 1 is a schematic side view showing an example of an imaging system according to the present invention.

FIG. 2 is a schematic plan view showing an image pickup section which constitutes the image pickup system of FIG.

FIG. 3 is a schematic plan view showing the image pickup unit of FIG. 1 including a horizontal charge transfer register formed for each solid-state image pickup device.

4 is a schematic plan view of the imaging system of FIG. 1 showing incident light with respect to each solid-state imaging device.

5A to 5C are explanatory diagrams showing the operation of the image processing apparatus.

FIG. 6 is a schematic side view showing an imaging system as a second embodiment example.

FIG. 7 is a schematic side view showing an image pickup system as a third embodiment.

FIG. 8 is a schematic side view showing an image pickup system as a fourth embodiment.

FIG. 9 is a schematic side view showing an imaging system as a fifth embodiment.

FIG. 10 is a schematic plan view showing an example of an imaging system having a structure in which one horizontal charge transfer register is provided for four solid-state imaging devices.

11A to 11C are partially enlarged plan views showing a part of a solid-state imaging device having a CCD structure.

[Explanation of symbols]

2 ... Imaging system, 4 ... Imaging unit, 6 ... Semiconductor substrate, 8, 10, 12, 14 ... Solid-state imaging device, 16 ...
Light-shielding film, 18 ... Horizontal charge transfer register, 22 ... Light distribution device, 24, 26, 28 ... Spectral prism, 30 ...
Lens, 38 Image processing device, 46 Imaging system, 48 Imaging unit, 50 Semiconductor substrate, 52 Solid state imaging device, 54 Solid state imaging device, 56 Optical distribution device, 58 , 60 ... Wide-angle lens, 62, 64 ... Prism, 66 ... Imaging system.

Continued front page    F-term (reference) 4M118 AA10 AB01 BA13 FA06 GB03                       GB07 GB20 GC07 GD07 GD13                       HA21 HA23 HA25                 5C022 AA11 AA13 AB46 AC42 AC51                       AC74                 5C024 CX01 EX41 EX47 GY01 HX01

Claims (12)

[Claims] 1. An imaging system configured by a solid-state imaging device that receives light from a subject and generates an electrical signal representing an image of the subject, the plurality of imaging systems being arranged close to each other and having different imaging characteristics. 2. An image pickup system comprising: the solid-state image pickup device and the light distribution device that makes light from the same subject incident on each of the solid-state image pickup devices simultaneously or sequentially. 2. The image pickup system according to claim 1, wherein the plurality of solid-state image pickup devices are formed on the same semiconductor chip. 3. The image pickup system according to claim 1, wherein the plurality of solid-state image pickup devices are formed on different semiconductor chips, respectively. 4. The image pickup system according to claim 1, wherein the light distribution device includes a spectral prism that divides light from the subject into each of the solid-state image pickup devices and makes the light incident thereon. 5. The light distribution device has a lens and a prism for each solid-state image pickup device, and light from the subject is converged by each lens so as to form an image on an image pickup surface of the solid-state image pickup device. 2. The imaging system according to claim 1, wherein the light emitted from the optical system changes its optical path in the direction of the corresponding solid-state imaging device by the corresponding prism. 6. The light distributing device comprises: an active prism that changes a shape to change a light emitting direction; and an actuator that drives the active prism to change a shape of the active prism and switches a light emitting direction. Light from the subject is incident on the active prism, and the direction of the emitted light is switched by driving the active prism by the actuator, whereby the light from the subject is sequentially incident on each solid-state imaging device. The imaging system according to claim 1, wherein 7. The light distribution device includes a mirror and a mirror drive means, reflects light from the subject by the mirror and makes the light incident on the solid-state imaging device, and the mirror drive means causes an angle of the mirror. 2. The imaging system according to claim 1, wherein one or both of the position and the position are changed so that the light from the subject is sequentially switched to enter each solid-state imaging device. 8. The light distribution device includes a solid-state image pickup device moving means for moving the plurality of solid-state image pickup devices as a whole, and the solid-state image pickup device moving means moves the whole solid-state image pickup device to move the solid-state image pickup device from the subject. 2. The image pickup system according to claim 1, wherein the light is sequentially incident on each solid-state image pickup device. 9. The imaging system according to claim 1, wherein at least one of the plurality of solid-state imaging devices has higher sensitivity than the other solid-state imaging devices. 10. The image pickup system according to claim 1, wherein at least one of the plurality of solid-state image pickup devices has better smear characteristics than the other solid-state image pickup devices. 11. At least one of the plurality of solid-state image pickup devices is for monochrome photography and does not include a color filter, and at least one of the other solid-state image pickup devices is for color photography. The image pickup system according to claim 1, further comprising a color filter. 12. An image processing device for synthesizing the image pickup results of the two solid-state image pickup devices, based on an electric signal representing the image pickup result of at least two solid-state image pickup devices among the plurality of solid-state image pickup devices. The imaging system according to claim 1.