JP2009147540A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device effectively correcting a black level with a simple configuration. <P>SOLUTION: The imaging device comprises a solid state image pickup device 5, an image sensor drive portion 10, and a digital signal processing portion 17. The solid state image pickup device 5 contains an RGB photoelectric conversion element group composed of photoelectric conversion elements 51R, 51G, and 51B and an rgb photoelectric conversion element group composed of photoelectric conversion elements 51r, 51g, and 51b. The image sensor drive portion 10 performs a first drive and a second drive in one imaging operation. At the first drive, an electron charge is read from the RGB photoelectric conversion element group and transferred to an output amplifier 58, and an image pick-up signal is output, according to the electron charge. At the second drive, a charge storage packet is transferred with the same transfer pattern as the first drive, and a dark current signal is output according to electron charge of a dark current component existing in the charge storage packet, while omitting read-out of electron charge from the rgb photoelectric conversion element group to the charge storage packet formed at a vertical charge transfer path 54, in association with each photoelectric conversion element in the rgb photoelectric conversion element group. The digital signal processing portion 17 corrects the image pick-up signal obtained by the first drive using the dark current signal acquired by the second drive. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention includes a large number of photoelectric conversion elements, reads charges generated by the large number of photoelectric conversion elements to a charge transfer path, transfers them to an output unit, and outputs a signal corresponding to the charges from the output unit The present invention relates to an imaging apparatus including a solid-state imaging element of a type.

  Conventionally, as a method for correcting a black level with a CCD (Charge Coupled Device) type solid-state image pickup device, a black level detection photoelectric conversion device (OB photoelectric conversion device) which is a photoelectric conversion device in which a light receiving surface is shielded from the solid-state image pickup device And a method of correcting the black level by subtracting the signal from the OB photoelectric conversion element from the signal from the photoelectric conversion element other than the OB photoelectric conversion element (see, for example, Patent Document 1), A method is known in which a CCD is driven under the same conditions so that only a dark current component is output from a solid-state imaging device, and the dark current component is subtracted from a signal obtained by photographing to perform black level correction.

JP 2001-16415 A

  As described above, the black level can be corrected by subtracting the dark output level from the sensor output. However, the dark output has dark shading, which varies depending on temperature and time in individual devices.

  Dark shading refers to non-uniformity in dark output that is noticeable in a CCD solid-state imaging device. It is desirable that the dark output level, which is a reference for signal output, is always kept uniform throughout the solid-state imaging device. However, there are actually various in-plane distributions. The main cause is dark current generation during charge transfer. The dark current generated in the CCD during charge transfer, particularly in the vertical CCD, is dominant, not the photoelectric conversion element itself. This dark current is generated unevenly. In addition, since the temperature dependence is large (the occurrence at high temperature is large), the level varies depending on the standby time (which is roughly divided into an exposure period and a charge transfer period).

  For this reason, the sensor output to be corrected and the dark output used for correction may be acquired at the same time, but this is not possible with the prior art. There is also a method of correcting the black level using the dark output level stored in advance, but since the dark output level changes according to the parameters of temperature and standby time in each device, a huge amount of Data must be prepared. In addition, in the method of obtaining dark output after photographing, it takes a long time to obtain dark output after obtaining sensor output, and it is difficult to say that dark output is obtained under the same conditions. In addition, since power consumption and time for two shootings are required before image data is recorded, it is difficult to satisfy the conditions required for a compact camera, such as shortening the time from shooting to recording and reducing power consumption.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an imaging device capable of effectively correcting a black level with a simple configuration.

  The imaging apparatus of the present invention includes a large number of photoelectric conversion elements, reads out charges generated by the large number of photoelectric conversion elements to a charge transfer path, transfers them to an output unit, and outputs a signal corresponding to the charges from the output unit An image pickup apparatus including a charge transfer type solid-state image pickup device, wherein the plurality of photoelectric conversion elements include a first photoelectric conversion element group and a second photoelectric conversion element group, and the first photoelectric conversion element A group of photoelectric conversion elements that detect light of a color component necessary for generating color image data, and the charge transfer path corresponding to each photoelectric conversion element of the first photoelectric conversion element group A first drive for reading out the charge from the first photoelectric conversion element group to the charge storage packet formed in the first packet and transferring it to the output unit and outputting an imaging signal corresponding to the charge; and the second photoelectric conversion element Corresponding to each photoelectric conversion element of the group Reading out the charge from the second photoelectric conversion element group to the charge accumulation packet formed in the charge transfer path and transferring the charge accumulation packet in the same transfer pattern as the first drive, Driving means for performing a second drive for outputting a dark current signal corresponding to the charge of the dark current component present in the charge accumulation packet by one imaging; and an imaging signal obtained by the first drive; Correction means for correcting using the dark current signal obtained by the second drive.

  In the imaging device of the present invention, the photoelectric conversion elements included in the first photoelectric conversion element group and the photoelectric conversion elements included in the second photoelectric conversion element group are orthogonal to the row direction on the semiconductor substrate, respectively. The first photoelectric conversion element group and the second photoelectric conversion element group are ½ of the arrangement pitch of each photoelectric conversion element in the row direction and the column. One charge transfer path is formed between two adjacent photoelectric conversion element rows among a plurality of photoelectric conversion element rows made of photoelectric conversion elements arranged in the column direction and arranged in the column direction; Between each of the plurality of photoelectric conversion elements and the charge transfer path adjacent thereto, a charge reading unit for reading the charge generated in each photoelectric conversion element to the charge transfer path is provided for each of the photoelectric conversion elements. Formed corresponding to the conversion element The charge reading unit corresponding to a part of the photoelectric conversion elements included in the photoelectric conversion element array and the charge reading unit corresponding to a photoelectric conversion element other than the part are formed between different charge transfer paths. The correction unit corrects the imaging signal obtained from any of the charge transfer paths using the dark current signal obtained from the any of the charge transfer paths.

  In the imaging apparatus of the present invention, the detection sensitivity of each photoelectric conversion element of the first photoelectric conversion element group is higher than the detection sensitivity of each photoelectric conversion element of the second photoelectric conversion element group.

  In the imaging apparatus according to the present invention, the plurality of photoelectric conversion elements are arranged in a square lattice pattern in a row direction on the semiconductor substrate and in a column direction orthogonal to the row direction, and the first photoelectric conversion element group and the second photoelectric conversion element are arranged. The photoelectric conversion element groups are arranged in a checkered pattern, and one charge transfer path is formed on the side of each of the plurality of photoelectric conversion element arrays composed of the photoelectric conversion elements arranged in the column direction. In addition, a charge reading unit is formed between each of the plurality of photoelectric conversion elements and the charge transfer path corresponding to the plurality of photoelectric conversion elements to read out charges generated in the respective photoelectric conversion elements to the charge transfer path. The correction unit corrects the imaging signal obtained from the arbitrary charge transfer path using the dark current signal obtained from the arbitrary charge transfer path.

  According to the present invention, it is possible to provide an imaging apparatus capable of effectively correcting the black level with a simple configuration.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a digital camera which is an example of an imaging apparatus for explaining a first embodiment of the present invention.
The imaging system of the digital camera shown in the figure includes a photographic lens 1, a CCD type solid-state imaging device 5, a diaphragm 2 provided therebetween, an infrared cut filter 3, and an optical low-pass filter 4.

  A system control unit 11 that performs overall control of the electrical control system of the digital camera controls the flash light emitting unit 12 and the light receiving unit 13 and controls the lens driving unit 8 to adjust the position of the photographing lens 1 to the focus position and zoom. The exposure amount is adjusted by adjusting the aperture amount of the aperture 2 via the aperture drive unit 9.

  Further, the system control unit 11 drives the solid-state imaging device 5 via the imaging device driving unit 10 and outputs a subject image captured through the photographing lens 1 as a color signal. An instruction signal from the user is input to the system control unit 11 through the operation unit 14.

  The electric control system of the digital camera further includes an analog signal processing unit 6 that performs analog signal processing such as correlated double sampling processing connected to the output of the solid-state imaging device 5, and RGB output from the analog signal processing unit 6. And an A / D conversion circuit 7 for converting the color signals into digital signals, which are controlled by the system control unit 11.

  Further, the electric control system of the digital camera performs image processing by performing black level correction, interpolation calculation, gamma correction calculation, RGB / YC conversion processing, and the like with the main memory 16 and the memory control unit 15 connected to the main memory 16. A digital signal processing unit 17 that generates data, a compression / expansion processing unit 18 that compresses image data generated by the digital signal processing unit 17 into a JPEG format or expands compressed image data, and digitally integrates photometric data. An integrating unit 19 for obtaining a gain for white balance correction performed by the signal processing unit 17, an external memory control unit 20 to which a detachable recording medium 21 is connected, and a liquid crystal display unit 23 mounted on the back of the camera or the like are connected. And a display control unit 22, which are connected to each other by a control bus 24 and a data bus 25, and receive commands from the system control unit 11. Thus it is controlled.

FIG. 2 is a schematic plan view showing a configuration example of the solid-state imaging device 5 shown in FIG.
The solid-state imaging device 5 is a photoelectric conversion device that detects light in the red (R) wavelength region (R light) arranged in a square lattice pattern in the row direction X on the semiconductor substrate 50 and the column direction Y orthogonal thereto. 51R (indicated by the letter “R” in the figure), photoelectric conversion element 51G for detecting light (G light) in the green (G) wavelength region (indicated by the letter “G” in the figure) An RGB photoelectric conversion element group including a photoelectric conversion element 51B (indicated by a letter “B” in the drawing) for detecting light (B light) in a blue (B) wavelength region, and the semiconductor substrate 50 A photoelectric conversion element 51r for detecting R light arranged in a square lattice pattern in the upper row direction X and a column direction Y orthogonal thereto (indicated by the letter “r” in the figure), G light A photoelectric conversion element 51g to detect (the letter “g” is attached in the figure), a photoelectric conversion element 51b to detect B light (in the figure, “b” Rgb photoelectric conversion element groups, which are arranged at positions shifted in the row direction X and the column direction Y by about ½ of the respective photoelectric conversion element arrangement pitches. Yes.

  The arrangement pitch of the photoelectric conversion elements of the RGB photoelectric conversion element group is the same as the arrangement pitch of the photoelectric conversion elements of the rgb photoelectric conversion element group. The photoelectric conversion element is, for example, a photodiode.

  A color filter is provided above each photoelectric conversion element of the RGB photoelectric conversion element group, and the arrangement of the color filters is a Bayer array. Similarly, a color filter is provided above each photoelectric conversion element of the rgb photoelectric conversion element group, and this color filter array is also a Bayer array.

  The detection sensitivity of each photoelectric conversion element of the RGB photoelectric conversion element group is higher than the detection sensitivity of each photoelectric conversion element of the rgb photoelectric conversion element group. To change the detection sensitivity of the photoelectric conversion element, the area of the light receiving surface of the photoelectric conversion element may be changed, or the light collection area may be changed by a microlens provided above the photoelectric conversion element, You may change the exposure time of a photoelectric conversion element. These methods are well known. The detection sensitivity of each photoelectric conversion element of the RGB photoelectric conversion element group may be the same as the detection sensitivity of each photoelectric conversion element of the rgb photoelectric conversion element group.

  The detection sensitivity of a photoelectric conversion element indicates a characteristic indicating how much signal can be extracted from the photoelectric conversion element when a predetermined amount of light is incident on the photoelectric conversion element. In other words, when the same amount of light is incident, a high-sensitivity photoelectric conversion element with a relatively high detection sensitivity has a characteristic that it can extract a larger amount of signal than a low-sensitivity photoelectric conversion element with a relatively low detection sensitivity. It can be defined as having. A high-sensitivity photoelectric conversion element can obtain many signals with a small amount of light, so it is ideal for shooting low-light subjects, but when a large amount of light is incident, the signal quickly saturates. Therefore, it is not suitable for photographing a high-illuminance subject. In addition, the low-sensitivity photoelectric conversion element cannot obtain a large amount of signal even when a large amount of light is incident, so it is optimal for photographing a subject with high illuminance. The obtained signal is too small and is not suitable for photographing a low-illuminance subject.

  The arrangement of each photoelectric conversion element of the RGB photoelectric conversion element group is such that a GR photoelectric conversion element array, which is a photoelectric conversion element array composed of a photoelectric conversion element 51G and a photoelectric conversion element 51R aligned in the column direction Y, and a photoelectric array in the column direction Y. It can be said that BG photoelectric conversion element arrays, which are photoelectric conversion element arrays including conversion elements 51B and 51G, are alternately arranged in the row direction X. In addition, the arrangement of the photoelectric conversion elements of the RGB photoelectric conversion element group is such that the photoelectric conversion element rows, which are photoelectric conversion element rows 51G and photoelectric conversion elements 51B arranged in the row direction X, are arranged in the row direction X. It can also be said that RG photoelectric conversion element rows, which are photoelectric conversion element rows composed of the aligned photoelectric conversion elements 51R and 51G, are alternately arranged in the column direction Y.

  The arrangement of the photoelectric conversion elements of the rgb photoelectric conversion element group includes a gr photoelectric conversion element array, which is a photoelectric conversion element array including a photoelectric conversion element 51g and a photoelectric conversion element 51r aligned in the column direction Y, and a photoelectric array in the column direction Y. It can be said that bg photoelectric conversion element arrays, which are photoelectric conversion element arrays including the conversion elements 51b and the photoelectric conversion elements 51g, are alternately arranged in the row direction X. In addition, the arrangement of the photoelectric conversion elements of the rgb photoelectric conversion element group is the gb photoelectric conversion element row, which is a photoelectric conversion element row composed of the photoelectric conversion elements 51g and the photoelectric conversion elements 51b arranged in the row direction X, and the row direction X. It can also be said that rg photoelectric conversion element rows, which are photoelectric conversion element rows composed of the aligned photoelectric conversion elements 51r and 51g, are alternately arranged in the column direction Y.

  On the right side of each photoelectric conversion element array, a vertical charge transfer path for transferring charges accumulated in the photoelectric conversion elements constituting each photoelectric conversion element array in the column direction Y corresponding to each photoelectric conversion element array 54 (only part of which is shown in FIG. 2) is formed. The vertical charge transfer path 54 is formed by, for example, n-type impurities injected into a p-well layer formed on an n-type silicon substrate.

  Above the vertical charge transfer path 54, transfer electrodes V <b> 1 to V <b> 8 are formed to which an eight-phase transfer pulse for controlling transfer of charges read out to the vertical charge transfer path 54 is applied by the image sensor driving unit 10. ing.

  The transfer electrodes V1 to V8 are arranged so as to meander between the photoelectric conversion element rows in the row direction X so as to avoid the photoelectric conversion elements constituting them. On the upper side of the gb photoelectric conversion element row, a transfer electrode V8 and a transfer electrode V1 are arranged in this order from the photoelectric conversion element row side between adjacent photoelectric conversion element rows. On the lower side of the gb photoelectric conversion element row, the transfer electrode V2 and the transfer electrode V3 are arranged in order from the gb photoelectric conversion element row side between the adjacent photoelectric conversion element rows. On the upper side of the rg photoelectric conversion element row, a transfer electrode V4 and a transfer electrode V5 are arranged in this order from the photoelectric conversion element row side between adjacent photoelectric conversion element rows. On the lower side of the rg photoelectric conversion element row, a transfer electrode V6 and a transfer electrode V7 are arranged in order from the rg photoelectric conversion element row side between the adjacent photoelectric conversion element rows.

  Between each photoelectric conversion element and the vertical charge transfer path 54 corresponding to the photoelectric conversion element, a charge reading unit 55 for reading the charge generated in each photoelectric conversion element to the vertical charge transfer path 54 is provided. The charge readout unit 55 is formed by a part of a p-well layer formed on an n-type silicon substrate, for example. The charge readout unit 55 is provided in the same direction (in the diagonally lower right direction in the drawing) with respect to each photoelectric conversion element.

  A transfer electrode V2 is formed above the charge reading unit 55 corresponding to each photoelectric conversion element in the gb photoelectric conversion element row, and a read pulse is applied to the transfer electrode V2 to each photoelectric conversion element in the gb photoelectric conversion element row. The accumulated charges can be read out to the vertical charge transfer path 54 on the right side of each photoelectric conversion element.

  A transfer electrode V4 is formed above the charge reading unit 55 corresponding to each photoelectric conversion element in the GB photoelectric conversion element row, and a read pulse is applied to each of the photoelectric conversion elements in the GB photoelectric conversion element row. The accumulated charges can be read out to the vertical charge transfer path 54 on the right side of each photoelectric conversion element.

  A transfer electrode V6 is formed above the charge reading unit 55 corresponding to each photoelectric conversion element in the rg photoelectric conversion element row, and by applying a read pulse to the transfer electrode V6, the transfer electrode V6 is applied to each photoelectric conversion element in the rg photoelectric conversion element row. The accumulated charges can be read out to the vertical charge transfer path 54 on the right side of each photoelectric conversion element.

  A transfer electrode V8 is formed above the charge reading unit 55 corresponding to each photoelectric conversion element in the RG photoelectric conversion element row, and a read pulse is applied to each of the photoelectric conversion elements in the RG photoelectric conversion element row. The accumulated charges can be read out to the vertical charge transfer path 54 on the right side of each photoelectric conversion element.

  A horizontal charge transfer path 57 for transferring the charges transferred through the vertical charge transfer path 54 in the row direction X is connected to the vertical charge transfer path 54. The horizontal charge transfer path 57 is connected to the horizontal charge transfer path 57. Is connected to an output amplifier 58 that converts the charge transferred to a voltage signal and outputs the voltage signal.

  The transfer electrodes (V2, V4, V6, V8) above the charge reading unit 55 are respectively provided with a middle level (VM, for example, 0V) transfer pulse VM for forming a packet for accumulating charges in the vertical charge transfer path 54. And a transfer pulse VL having a low level (VL, for example, −8 V) lower than the VM for forming a barrier of the packet in the vertical charge transfer path 54, and a charge from each photoelectric conversion element to the vertical charge transfer path 54. Or a read pulse having a level higher than VM (VH, for example, 15 V) can be applied. Any transfer pulse of VL and VM can be applied to the transfer electrodes (V1, V3, V5, V7) other than the transfer electrodes (V2, V4, V6, V8) above the charge reading unit 55. .

A method for driving the solid-state imaging device 5 configured as described above will be described. Hereinafter, driving in the photographing mode in which image data is generated using only signals obtained from the RGB photoelectric conversion element group will be described.
When the photographing mode is set and photographing is performed and the exposure period by the photographing is completed, the transfer pulse VM is applied to the transfer electrodes V4 and V8, respectively, and the charge corresponding to each photoelectric conversion element of the RGB photoelectric conversion element group. Accumulated packets are formed under the transfer electrodes V4 and V8. In this state, a read pulse is applied to each of the transfer electrodes V4 and V8, and charges generated in each photoelectric conversion element of the RGB photoelectric conversion element group are read out to a charge accumulation packet formed corresponding to each photoelectric conversion element. It is. Next, a transfer pulse of a predetermined pattern is applied to the transfer electrodes V1 to V8, and the charge read out in the charge accumulation packet is transferred to the horizontal charge transfer path 57 and transferred from here to the output unit 58, where It is converted and output, and the first field ends. Hereinafter, the signal obtained in the first field is also referred to as an imaging signal.

  Next, the transfer pulse VM is applied to the transfer electrodes V2 and V6, respectively, and a charge accumulation packet corresponding to each photoelectric conversion element of the rgb photoelectric conversion element group is formed under the transfer electrodes V2 and V6. Thereafter, the read pulse is not applied to the transfer electrodes V2 and V6, and the transfer pulse having the same predetermined pattern as that of the first field is applied to the transfer electrodes V1 to V8, and the dark current component existing in the charge accumulation packet is applied. Are transferred to the horizontal charge transfer path 57 in the same transfer pattern as the charge in the first field, transferred from here to the output unit 58, converted into a signal and output here, and the second field is completed. Hereinafter, the signal obtained in the second field is also referred to as a dark current signal.

  The reason why the charge accumulation packet is transferred in the second field with the same transfer pattern as that in the first field is to obtain a dark current signal under the same conditions as possible as an imaging signal.

  The signals obtained in the first field and the second field are digitally converted and then input to the digital signal processing unit 17. The digital signal processing unit 17 performs processing for correcting the imaging signal obtained in the first field using the dark current signal obtained in the second field.

For example, the charge accumulation formed corresponding to the photoelectric conversion element (the upper right photoelectric conversion element 51g of the photoelectric conversion element 51G) close to the photoelectric conversion element 51G from the imaging signal obtained from the photoelectric conversion element 51G of FIG. The dark current signal obtained from the packet is subtracted to correct the dark current component generated in the vertical charge transfer path 54.
Similarly, from the imaging signal obtained from the photoelectric conversion element 51R in FIG. 2, the charge formed corresponding to the photoelectric conversion element (the upper right photoelectric conversion element 51r of the photoelectric conversion element 51R) close to the photoelectric conversion element 51R. The process of subtracting the dark current signal obtained from the accumulated packet, the photoelectric conversion element adjacent to the photoelectric conversion element 51B (photoelectric conversion at the upper right of the photoelectric conversion element 51B) from the imaging signal obtained from the photoelectric conversion element 51B of FIG. A process of subtracting the dark current signal obtained from the charge storage packet formed corresponding to the element 51b) is performed. By this processing, an imaging signal obtained by removing dark current components generated in the vertical charge transfer path 54 from the imaging signal obtained from the RGB photoelectric conversion element group can be obtained.

  The digital signal processing unit 17 generates color image data using the imaging signal after dark current removal. The generated color image data is compressed and then recorded on the recording medium 21.

  According to the driving method as described above, an imaging signal from the RGB photoelectric conversion element group and a dark current signal for correcting the imaging signal can be obtained by one imaging. That is, since the imaging signal and the dark current signal for correcting the dark current component can be acquired without a large time difference, these two signals can be obtained under substantially the same conditions. As a result, dark current can be removed with high accuracy, and the black level can be corrected with high accuracy.

  In addition, according to the above driving method, since the imaging signal and the dark current signal can be obtained by one imaging, it is possible to shorten the time from photographing to recording and to reduce power consumption. In addition, since it is not necessary to have correction data in advance, the cost of the digital camera can be reduced.

  In the digital camera of this embodiment, it is also possible to perform imaging with an expanded dynamic range by synthesizing an imaging signal obtained from the RGB photoelectric conversion element group and an imaging signal obtained from the rgb photoelectric conversion element group. In this case, in the second field of the driving method described above, after forming a charge accumulation packet corresponding to each photoelectric conversion element of the rgb photoelectric conversion element group, a read pulse is applied to the transfer electrodes V2 and V6, and After the charge is transferred from the photoelectric conversion element to the charge storage packet, the charge is transferred in the predetermined pattern.

  As described above, when driving to omit the application of the readout pulse in the second field, image data is generated only with imaging signals from the RGB photoelectric conversion element group which is a high-sensitivity photoelectric conversion element. Since an image pickup signal obtained from a high-sensitivity photoelectric conversion element has a small signal amount, a ratio of noise (S / N ratio) in the entire signal is increased. For this reason, it is effective to perform correction for removing dark current components that become noise using a signal from an empty charge storage packet. On the other hand, when the charge is read from the rgb photoelectric conversion element group in the second field, the S / N ratio is improved as compared with the case where the charge read is omitted. Therefore, the dark current component is not removed. , Image quality can be maintained.

  According to the configuration of the solid-state imaging device of the present embodiment, driving in the case of generating image data only with imaging signals obtained from the RGB photoelectric conversion element group, imaging signals obtained from the RGB photoelectric conversion element group, and rgb photoelectric conversion element Since driving for generating image data with an imaging signal obtained from a group can be switched only by the presence or absence of application of a readout pulse, the design of the driving pattern is facilitated.

  Note that, as described above, driving in the case where image data is generated using only imaging signals obtained from the RGB photoelectric conversion element group may be performed in, for example, a high-sensitivity imaging mode. In addition, in the configuration shown in FIG. 2, the present invention can be applied to a configuration in which each photoelectric conversion element of the rgb photoelectric conversion element group is changed to a photoelectric conversion element provided with a luminance filter above the light receiving surface.

  The luminance filter is a filter having spectral characteristics correlated with light luminance information. This luminance filter corresponds to an ND filter, a transparent filter, a white filter, a gray filter, or the like, but the configuration in which light is directly incident on the light receiving surface without providing anything above the light receiving surface of the photoelectric conversion element is also possible. It can be said that a filter is provided.

(Second embodiment)
FIG. 3 is a schematic plan view showing a second embodiment of the solid-state imaging device mounted on the digital camera shown in FIG. 3, the same components as those in FIG. 2 are denoted by the same reference numerals.
The solid-state imaging device 5 illustrated in FIG. 3 corresponds to the charge reading unit 55 corresponding to each photoelectric conversion element in the RG photoelectric conversion element row of the solid-state imaging device 5 illustrated in FIG. 2 and each photoelectric conversion element in the rg photoelectric conversion element row. The charge reading unit 55 is provided not between the vertical charge transfer path 54 adjacent to the right of each photoelectric conversion element but between the vertical charge transfer path 54 adjacent to the left.

  That is, when attention is paid to an arbitrary photoelectric conversion element array, a charge reading unit corresponding to half of the photoelectric conversion elements (odd-numbered photoelectric conversion elements) constituting the photoelectric conversion element array and the other half (even-numbered photoelectric conversion) The charge readout section corresponding to the element) is provided between different vertical charge transfer paths 54. The type of transfer electrode provided above each charge readout section 55 is the same as in FIG.

  The details of the configuration shown in FIG. 3 are also disclosed in Japanese Patent Application Laid-Open No. 2004-055586, so please refer to this.

  The driving method of the solid-state imaging device 5 configured in this way is the same as the method described in the first embodiment. That is, in a shooting mode in which image data is generated only by signals obtained from the RGB photoelectric conversion element group, a transfer pulse VM is applied to the transfer electrodes V4 and V8 in the first field to form a charge accumulation packet, and then the transfer electrode V4 is formed. , V8 is applied with a readout pulse to read out charges from the photoelectric conversion elements of the RGB photoelectric conversion element group to the charge storage packet, and this is transferred to output an imaging signal corresponding to the charges. Then, in the second field, a transfer pulse VM is applied to the transfer electrodes V2 and V6 to form a charge storage packet, and then the read charge pulse is not applied to the transfer electrodes V2 and V6. And a signal corresponding to the charge of the dark current component stored in the packet is output.

  The signals obtained in the first field and the second field are digitally converted and then input to the digital signal processing unit 17. The digital signal processing unit 17 performs processing for correcting the signal obtained in the first field using the signal obtained in the second field. Specifically, the digital signal processing unit 17 corrects the imaging signal obtained in the first field from a certain vertical charge transfer path 54 by using the dark current signal obtained in the second field from the vertical charge transfer path 54. To do.

For example, taking the vertical charge transfer path 54 at the leftmost in FIG. 3 as an example, the digital signal processing unit 17 performs photoelectric conversion adjacent to the photoelectric conversion element 51G from an imaging signal obtained from the photoelectric conversion element 51G. The dark current signal obtained from the charge storage packet formed corresponding to the element 51r is subtracted.
Taking the vertical charge transfer path 54 as the second from the left in FIG. 3 as an example, the digital signal processing unit 17 uses a photoelectric conversion element adjacent to the photoelectric conversion element 51G from an imaging signal obtained from the photoelectric conversion element 51G. The dark current signal obtained from the charge storage packet formed corresponding to 51g is subtracted.
Taking the vertical charge transfer path 54 third from the left in FIG. 3 as an example, the digital signal processing unit 17 uses a photoelectric conversion element adjacent to the photoelectric conversion element 51B from an imaging signal obtained from the photoelectric conversion element 51B. The dark current signal obtained from the charge storage packet formed corresponding to 51g is subtracted.
Taking the fourth vertical charge transfer path 54 from the left in FIG. 3 as an example, the digital signal processing unit 17 uses a photoelectric conversion element adjacent to the photoelectric conversion element 51R based on an imaging signal obtained from the photoelectric conversion element 51R. The dark current signal obtained from the charge storage packet formed corresponding to 51b is subtracted.

  By such processing, an imaging signal obtained by removing the dark current component generated in the vertical charge transfer path 54 from the imaging signal obtained from the RGB photoelectric conversion element group can be obtained.

  As described above, according to the solid-state imaging device of this embodiment, the imaging signal from the RGB photoelectric conversion element group and the signal for correcting the imaging signal can be acquired from the same vertical charge transfer path 54. it can. For this reason, the correlation between the dark current component included in the imaging signal to be corrected and the signal for correcting the imaging signal can be increased, and the dark current can be removed with higher accuracy.

(Third embodiment)
FIG. 4 is a schematic plan view showing a third embodiment of the solid-state imaging device mounted on the digital camera shown in FIG.
The solid-state imaging device shown in FIG. 4 includes a photoelectric conversion element 61R provided with a color filter that transmits R light above, a photoelectric conversion element 61G provided with a color filter that transmits G light, and B light. A photoelectric conversion element 61B having a transparent color filter provided above and a photoelectric conversion element 61W having a luminance filter provided above are arranged in a square lattice pattern in a row direction on the semiconductor substrate and in a column direction perpendicular thereto. It has become. The photoelectric conversion elements 61R, 61G, 61B and the photoelectric conversion element 61W are arranged in a checkered pattern.

  A vertical charge transfer path 64 is formed on the side of the photoelectric conversion element array composed of photoelectric conversion elements arranged in the column direction corresponding to the photoelectric conversion element array. The vertical charge transfer path 64 transfers charges generated in the photoelectric conversion elements of the corresponding photoelectric conversion element array in the column direction.

  At the end of the vertical charge transfer path 64, there is provided a horizontal charge transfer path 67 for transferring the charges transferred through the vertical charge transfer path 64 in the row direction. At the end of the horizontal charge transfer path 67, a horizontal charge transfer path is provided. An output amplifier 68 is provided for outputting a signal corresponding to the charge transferred to 67.

  Between the vertical charge transfer path 54 and each photoelectric conversion element of the corresponding photoelectric conversion element array, a charge reading unit 65 (see FIG. 5) for reading out the charge generated in each photoelectric conversion element to the vertical charge transfer path 54. 4 is schematically shown by an arrow). A readout pulse can be applied independently to the charge readout unit 65 corresponding to the photoelectric conversion elements 61R, 61B, and 61G and the charge readout unit 65 corresponding to the photoelectric conversion element 61W. The details of the solid-state imaging device shown in FIG. 4 are described in Japanese Patent Application Laid-Open No. 2003-318375, so please refer to this.

A driving method of the solid-state imaging device configured as described above will be described. Hereinafter, driving in the photographing mode in which image data is generated using only signals obtained from the photoelectric conversion elements 61R, 61G, and 61B will be described.
When the photographing mode is set and photographing is performed and the exposure period by the photographing is completed, the transfer pulse is transferred to a position adjacent to the charge reading unit 65 corresponding to the photoelectric conversion elements 61R, 61G, and 61B of each vertical charge transfer path 64. A VM is applied to form a charge storage packet. Thereafter, a read pulse is applied to the charge reading unit 65, and the charges generated in the photoelectric conversion elements 61R, 61G, 61B are read into the charge accumulation packet. Next, a transfer pulse having a predetermined pattern is applied to the vertical charge transfer path 65, and the charge read out to the charge accumulation packet is transferred to the horizontal charge transfer path 67 and transferred from here to the output unit 68, where signal The first field ends.

  Next, the transfer pulse VM is applied to a position adjacent to the charge reading unit 65 corresponding to the photoelectric conversion element 61W in each vertical charge transfer path 64, thereby forming a charge accumulation packet. Thereafter, the readout pulse is not applied to the charge readout unit 65 corresponding to the photoelectric conversion element 61W, and the transfer pulse having the same predetermined pattern as that of the first field is applied to the vertical charge transfer path 65 to Are transferred to the horizontal charge transfer path 67 in the same transfer pattern as the charge in the first field, transferred from here to the output unit 68, converted into a signal, and output, and the second field is completed.

  The signals obtained in the first field and the second field are digitally converted and then input to the digital signal processing unit 17. The digital signal processing unit 17 performs processing for correcting the signal obtained in the first field using the signal obtained in the second field. Specifically, the digital signal processing unit 17 corrects the imaging signal obtained in the first field from a certain vertical charge transfer path 64 by using the signal obtained in the second field from the vertical charge transfer path 64.

  For example, taking the vertical charge transfer path 64 on the leftmost side of FIG. 4 as an example, the digital signal processing unit 17 performs photoelectric conversion in the vicinity of the photoelectric conversion element 61R from the imaging signal obtained from the photoelectric conversion element 61R. The dark current signal obtained from the charge storage packet formed corresponding to the element 61W is subtracted, and the image pickup signal obtained from the photoelectric conversion element 61B corresponds to the photoelectric conversion element 61W adjacent to the photoelectric conversion element 61B. The dark current signal obtained from the charge storage packet formed in this way is subtracted.

  By performing such processing on all the imaging signals, an imaging signal obtained by removing dark current components generated in the vertical charge transfer path 64 from the imaging signals obtained from the photoelectric conversion elements 61R, 61G, and 61B can be obtained. it can.

  As described above, even in the configuration shown in FIG. 4, the image signal from the photoelectric conversion elements 61R, 61G, and 61B and the signal for correcting the image signal are used in the same vertical charge transfer path 64. Can be obtained from.

The figure which shows schematic structure of the digital camera which is an example of the imaging device for demonstrating 1st embodiment of this invention. FIG. 1 is a schematic plan view showing a configuration example of the solid-state imaging device shown in FIG. The plane schematic diagram which shows 2nd embodiment of the solid-state image sensor mounted in the digital camera shown in FIG. The plane schematic diagram which shows 3rd embodiment of the solid-state image sensor mounted in the digital camera shown in FIG.

Explanation of symbols

5 Solid-State Image Sensor 10 Image Sensor Drive Unit 17 Digital Signal Processing Units 51R, 51G, 51B High Sensitivity Photoelectric Conversion Elements 51r, 51g, 51b Low Sensitivity Photoelectric Conversion Elements

Claims (4)

A charge transfer type solid-state imaging device that includes a large number of photoelectric conversion elements, reads charges generated by the large number of photoelectric conversion elements to a charge transfer path, transfers them to an output unit, and outputs a signal corresponding to the charges from the output unit An imaging device including an element,
The multiple photoelectric conversion elements are composed of a first photoelectric conversion element group and a second photoelectric conversion element group,
The first photoelectric conversion element group is composed of photoelectric conversion elements that detect light of a color component necessary for generating color image data;
The charge is read from the first photoelectric conversion element group to the charge storage packet formed in the charge transfer path corresponding to each photoelectric conversion element of the first photoelectric conversion element group, and transferred to the output unit. A first drive for outputting an imaging signal corresponding to the second photoelectric conversion element, and the second photoelectric conversion element to the charge storage packet formed in the charge transfer path corresponding to each photoelectric conversion element of the second photoelectric conversion element group The readout of the charge from the group is omitted, and the charge accumulation packet is transferred in the same transfer pattern as the first drive, and a dark current signal corresponding to the charge of the dark current component existing in the charge accumulation packet is output. Driving means for performing the second driving to be performed by one imaging;
An image pickup apparatus comprising: a correction unit that corrects the image pickup signal obtained by the first drive using the dark current signal obtained by the second drive. The imaging apparatus according to claim 1,
The photoelectric conversion elements included in the first photoelectric conversion element group and the photoelectric conversion elements included in the second photoelectric conversion element group are each in the form of a square lattice in the row direction on the semiconductor substrate and in the column direction perpendicular thereto. Are arranged in
The first photoelectric conversion element group and the second photoelectric conversion element group are arranged to be shifted in the row direction and the column direction by 1/2 of the arrangement pitch of the photoelectric conversion elements,
One charge transfer path is formed between two adjacent photoelectric conversion element arrays among a plurality of photoelectric conversion element arrays composed of photoelectric conversion elements arranged in the column direction,
Between each of the plurality of photoelectric conversion elements and the charge transfer path adjacent thereto, a charge reading unit for reading the charge generated in each photoelectric conversion element to the charge transfer path is provided for each of the photoelectric conversion elements. It is formed corresponding to the conversion element,
The charge reading unit corresponding to a part of the photoelectric conversion elements included in the photoelectric conversion element array and the charge reading unit corresponding to a photoelectric conversion element other than the part are formed between different charge transfer paths. Has been
The said correction | amendment means is an imaging device which correct | amends the said imaging signal obtained from the arbitrary said charge transfer paths using the said dark current signal obtained from the said arbitrary said charge transfer paths. The imaging apparatus according to claim 1 or 2,
An imaging apparatus in which detection sensitivity of each photoelectric conversion element of the first photoelectric conversion element group is higher than detection sensitivity of each photoelectric conversion element of the second photoelectric conversion element group. The imaging apparatus according to claim 1,
The plurality of photoelectric conversion elements are arranged in a square lattice pattern in a row direction on the semiconductor substrate and in a column direction perpendicular thereto.
The first photoelectric conversion element group and the second photoelectric conversion element group are arranged in a checkered pattern,
One charge transfer path is formed on the side of each of a plurality of photoelectric conversion element columns formed of photoelectric conversion elements arranged in the column direction,
Between each of the plurality of photoelectric conversion elements and the charge transfer path corresponding thereto, a charge reading unit is formed for reading the charge generated in each photoelectric conversion element to the charge transfer path,
The said correction | amendment means is an imaging device which correct | amends the said imaging signal obtained from arbitrary said charge transfer paths using the said dark current signal obtained from said arbitrary said charge transfer paths.

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