JP2004080690A - Ccd solid-state imaging element and camera system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CCD (charge-coupled device) solid-state imaging element which enables a high-speed readout through a multi-amplifier readout and prevents an effect of the dispersion of amplifier characteristics on image quality. <P>SOLUTION: In the CCD solid-state imaging element 10 having a color filter, horizontal CCDs 14, 15 are arranged above and below an imaging area 11 comprising optical detectors, respectively, and signal charges are sent from vertical CCDs 12, 13 to the horizontal CCDs 14, 15 in separate directions at respective odd lows and even rows of the optical detectors. As a result, the amplifiers 16, 17 arranged respectively at the final stages of the horizontal CCDs 14, 15 read out different color information, respectively, so that the dispersion of amplifier characteristics can be absorbed by the characteristics of the color filter, thereby reading out the color information at a high speed without the effect of the dispersion of amplifier characteristics on image quality. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a CCD solid-state imaging device and a camera system using the same.
[0002]
[Prior art]
2. Description of the Related Art In recent years, the CCD type solid-state imaging device has been developed to have a higher number of pixels due to miniaturization of a process, and a higher definition image can be taken. However, on the other hand, the readout speed has become an issue as the number of pixels increases. Various attempts have been made to solve this problem.
[0003]
According to the first related art, a plurality of horizontal CCDs are provided on one side of an imaging area of each solid-state imaging device in a three-panel high-definition (HD) television system, and an amplifier provided at the last stage of each horizontal CCD. Read the signal charge. However, since variations in amplifier characteristics (gain, offset, etc.) pose a problem, a reference signal for correcting this is distributed to each horizontal CCD (Japanese Patent Laid-Open No. 2-78382).
[0004]
Further, according to the second prior art, the image pickup area is divided into two parts, left and right, and the signal charges are transferred to the horizontal CCD. The signal charges of each block are transferred in opposite directions in the horizontal direction. A signal charge is read out by each of the provided amplifiers (Japanese Patent Laid-Open No. 3-224371).
[0005]
Further, according to the third prior art, in a solid-state image pickup device of an interlaced readout (pixel addition readout) method, horizontal CCDs are respectively provided on both upper and lower sides of an image pickup area, and signal charges in odd columns are transferred to a lower horizontal CCD. The signal charges in the even columns are transferred to the upper horizontal CCDs, respectively, and the signal charges are read out by an amplifier provided at the last stage of each horizontal CCD (Japanese Patent Laid-Open No. 8-125158).
[0006]
On the other hand, as one conventional technique in a non-CCD type solid-state imaging device, there is known a technique of always outputting the same color to each output terminal while keeping the color filter arrangement as conventional (Japanese Patent Laid-Open No. 9-46480).
[0007]
[Problems to be solved by the invention]
Generally, it is difficult to manufacture an element having completely uniform amplifier characteristics. Therefore, in the first to third prior arts, a means for correcting variations in amplifier characteristics is indispensable.
[0008]
The present invention relates to a single-chip CCD solid-state imaging device that does not affect image quality even if the amplifier characteristics are different when a plurality of read amplifiers are employed to increase the reading speed, and a camera system using the same. The purpose is to provide.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured so that the same color information does not pass through different amplifiers. For example, the same R (red) information is prevented from passing through two amplifiers having different characteristics. However, in the color arrangement of the color filters, for example, G (green) sandwiched by R (red) and G (green) sandwiched by B (blue) can be handled as different colors.
[0010]
According to the present invention, different color information is read out by the amplifier placed at the last stage of each horizontal CCD. Therefore, variations in the amplifier characteristics can be absorbed by the color filter characteristics, and the variations in the amplifier characteristics can be read at high speed without affecting the image quality.
[0011]
More specifically, the invention according to claim 1 is, as exemplified in FIG. 1, in a CCD solid-state imaging device in which a plurality of photodetectors are two-dimensionally arranged in an imaging area, the plurality of photodetectors are superposed on the plurality of photodetectors. A color filter that does not have the same color in the odd-numbered and even-numbered columns or has a different adjacent color even if it is the same color, and the signal charges of the odd-numbered photodetectors of the plurality of photodetectors in the vertical direction. A first vertical CCD for transferring upward or downward to the first vertical CCD, and a second vertical CCD for transferring signal charges of photodetectors in an even-numbered row of the plurality of photodetectors in a direction opposite to the first vertical CCD. , A first horizontal CCD for transferring the signal charges received from the first vertical CCD in the horizontal direction, and a second horizontal CCD for transferring the signal charges received from the second vertical CCD in the horizontal direction. Horizontal CCD and the final stage of the first horizontal CCD A first amplifier is provided and a second amplifier is provided at the last stage of the second horizontal CCD, and the signal charges of the odd-numbered columns and the even-numbered columns are separately read from the first and second amplifiers, respectively. It was decided.
[0012]
According to a second aspect of the present invention, there is provided a CCD solid-state imaging device in which a plurality of photodetectors are two-dimensionally arranged in an imaging area as illustrated in FIG. A color filter that does not have the same color or the same color but has different adjacent colors in the even rows, a vertical CCD for transferring signal charges of a plurality of photodetectors in a vertical direction, and a plurality of photodetectors. A first horizontal CCD for receiving the signal charges of the photodetectors of the odd rows of the detectors from the vertical CCDs and transferring the received signal charges in the horizontal direction, and the light of the even rows of the plurality of photodetectors. A second horizontal CCD for receiving the signal charge of the detector from the vertical CCD and transferring the received signal charge in the horizontal direction; a first amplifier provided at the last stage of the first horizontal CCD; Of the horizontal CCD And a amplifier, respectively odd rows from the first and second amplifier is obtained by the reading the even rows of the signal charges separately.
[0013]
Further, according to a third aspect of the present invention, as illustrated in FIG. 3, in a CCD solid-state imaging device in which a plurality of photodetectors are two-dimensionally arranged in an imaging region, an odd number of rows are superimposed on the plurality of photodetectors. A color filter that does not have the same color in the even-numbered columns or has a different adjacent color even if it is the same color, and does not have the same color in the odd-numbered and even-numbered rows or has a different adjacent color even if it is the same color; A first vertical CCD for vertically or vertically transferring signal charges of odd-numbered photodetectors of the plurality of photodetectors, and photodetection of even-numbered columns of the plurality of photodetectors. A second vertical CCD for transferring the signal charge of the detector in the opposite direction to the first vertical CCD, and the signal charge of an odd-numbered row and an odd-numbered column of the photodetectors among the plurality of photodetectors. For transferring the received signal charges from the vertical CCD in the horizontal direction. A second horizontal CCD for receiving signal charges of the photodetectors in the even rows and odd columns of the plurality of photodetectors from the first vertical CCD and transferring the received signal charges in the horizontal direction; A horizontal CCD, a first amplifier provided at the last stage of the first horizontal CCD, a second amplifier provided at the last stage of the second horizontal CCD, and an odd row of the plurality of photodetectors. A third horizontal CCD for receiving the signal charges of the photodetectors in the even columns from the second vertical CCD and transferring the received signal charges in the horizontal direction; and an even row and an even number of the plurality of photodetectors. A fourth horizontal CCD for receiving the signal charges of the photodetectors in the column from the second vertical CCD and transferring the received signal charges in the horizontal direction, and a third horizontal CCD provided at the last stage of the third horizontal CCD. And the last stage of the fourth horizontal CCD Read out the signal charges of odd rows and odd columns, even rows and odd columns, odd rows and even columns, even rows and even columns from the first to fourth amplifiers, respectively. It is what it was.
[0014]
According to a fourth aspect of the present invention, as shown in FIGS. 4 to 7, in the CCD type solid-state imaging device according to the first or third aspect of the present invention, the first and second vertical CCDs include a plurality of photodetectors. Has a transfer gate structure capable of progressively reading (non-additional reading of all pixels) the signal charges and transferring the signal charges in opposite directions by the same drive pulse train.
[0015]
A fifth aspect of the present invention is a camera system using the CCD solid-state imaging device according to any one of the first to fourth aspects of the present invention, as exemplified in FIGS.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0017]
1 to 3 show schematic views of a single-plate CCD solid-state imaging device. Each is a CCD type solid-state imaging device having a Bayer array color filter. In the illustrated color filter array, R is red, Gr and Gb are green, and B is blue. Gr is green next to R in the horizontal direction, and Gb is green next to B in the horizontal direction. Gr and Gb are both green, but are treated as different colors because the filters located on the left and right are different.
[0018]
The CCD type solid-state imaging device 10 of FIG. 1 has a configuration in which a plurality of photodetectors (photodiodes) are two-dimensionally arranged in an imaging area 11 and a color filter is superimposed thereon. The charges converted by the photodetector having the R and Gb color filters are transferred to the horizontal CCD 14 disposed below via the vertical CCD 12. On the other hand, the charges converted by the photodetector having the Gr and B color filters are transferred via the vertical CCD 13 to the horizontal CCD 15 arranged on the upper side. Thus, the signal charge having the color information of R and Gb is in the last stage of the lower horizontal CCD 14, and the signal charge having the color information of Gr and B is in the last stage of the upper horizontal CCD 15. Respectively. As a result, since the amplifiers 16 and 17 read different color information, variations in the amplifier characteristics can be absorbed by the color filter characteristics, and the variations in the amplifier characteristics can be read at high speed without affecting the image quality. Note that any color filter that does not have the same color in the odd-numbered row and the even-numbered row, or has the same color but has a different adjacent color, is not limited to the Bayer array, and any color filter that can reproduce colors is employed. be able to.
[0019]
The CCD-type solid-state imaging device 20 shown in FIG. 2 has a configuration in which a plurality of photodetectors are two-dimensionally arranged in an imaging area 21 and a color filter is superimposed thereon. The charges converted by the photodetector having the R and Gr color filters are transferred to the upper horizontal CCD 24 of the lower two horizontal CCDs 24 and 25 via the vertical CCDs 22 and 23. On the other hand, the electric charge converted by the photodetector having the Gb and B color filters is transferred to the lower horizontal CCD 25 of the lower two horizontal CCDs 24 and 25 via the vertical CCDs 22 and 23. . Thus, the signal charge having the color information of R and Gr is in the last stage of the upper horizontal CCD 24, and the signal charge having the color information of Gb and B is in the last stage of the lower horizontal CCD 25. Respectively. Thus, since the amplifiers 26 and 27 read different color information, variations in the amplifier characteristics can be absorbed by the color filter characteristics, and the variations in the amplifier characteristics can be read at high speed without affecting the image quality. Note that any color filter that does not have the same color in the odd-numbered row and the even-numbered row, or has the same color but has a different adjacent color, is not limited to the Bayer array, and may employ any color filter that can reproduce colors. be able to.
[0020]
The CCD solid-state imaging device 30 shown in FIG. 3 has a configuration in which a plurality of photodetectors are two-dimensionally arranged in an imaging area 31 and a color filter is superimposed thereon. As in FIG. 1, the charges converted by the photodetector having the R and Gb color filters are transferred to the lower side via the vertical CCD 32, and the charges converted by the photodetector having the Gr and B color filters are transferred to the vertical CCD 33. Are transferred to the upper side respectively. At this time, the charge of R is transferred to the upper horizontal CCD (first horizontal CCD) 34 of the lower two horizontal CCDs 34 and 35, and the charge of Gb is transferred to the lower horizontal CCD (second horizontal CCD). (CCD) 35. The electric charge of Gr is supplied to the upper horizontal CCD (third horizontal CCD) 38 of the two horizontal CCDs 38 and 39 arranged on the upper side, and the electric charge of B is supplied to the lower horizontal CCD (fourth horizontal CCD). 39, respectively. Thus, the signal charge having the color information of R is provided by the amplifier 36 at the last stage of the first horizontal CCD 34, and the signal charge having the color information of Gb is provided by the amplifier 37 at the last stage of the second horizontal CCD 35. The signal charge having the color information B is read out by the amplifier 40 at the last stage of the third horizontal CCD 38, and the signal charge having the color information B is read out by the amplifier 41 at the last stage of the fourth horizontal CCD 39. Thus, since the amplifiers 36, 37, 40, and 41 read different color information, variations in the amplifier characteristics can be absorbed by the color filter characteristics, and the variations in the amplifier characteristics can be read at high speed without affecting the image quality. It should be noted that the odd columns and the even columns do not have the same color, or have the same color but have different adjacent colors, and the odd and even rows do not have the same color or differ even if they have the same color. As long as the color filters have adjacent colors, any color filters capable of reproducing colors can be employed without being limited to the Bayer arrangement.
[0021]
FIGS. 4 and 5 show an example of the electrode structure of the vertical CCDs 12 and 13; 32 and 33 which enable the reverse charge transfer shown in FIGS. Here, progressive readout (non-additional readout of all pixels) of signal charges is possible, and four-phase transfer is performed using a two-layer polysilicon process.
[0022]
FIG. 4 is a top view of the electrode structure of the transfer gate, and FIGS. 5A and 5B show cross sections of AA ′ and BB ′ shown in FIG. 4, respectively. It is. In FIGS. 5A and 5B, PD is a photodiode, which is not actually on a cross section but is shown by a dotted line to show a positional relationship with an electrode. Here, the electrode for reading signal charges from the PD is φV1.
[0023]
By adopting the electrode structure shown in FIGS. 4 and 5, the odd-numbered rows are arranged in the downward direction φV1 → φV2 → φV3 → φV4, while the even-numbered rows are arranged upwardly in the order of φV4 → φV3 → φV2 → φV1. Is transferred.
[0024]
6 and 7 show timing charts of the reverse transfer. FIG. 6 shows pulse waveforms applied to φV1, φV2, φV3, and φV4, and FIG. 7 schematically shows a transfer state. When the transfer pulse shown in FIG. 6 is applied to the four-phase gate electrodes shown in FIGS. 4 and 5, in the odd-numbered columns, the charges are arranged because φV1 → φV2 → φV3 → φV4 in order from top to bottom. The charges are transferred to the lower horizontal CCD, and the charges are transferred to the upper horizontal CCD since the gate electrodes are arranged in the order of φV4 → φV3 → φV2 → φV1 from the bottom in the even-numbered column. Thus, the reverse transfer is performed alternately for each column.
[0025]
FIG. 8 shows an example of a camera system using the CCD type solid-state imaging devices 10 and 20 shown in FIG. 1 or FIG. In FIG. 8, reference numeral 50 denotes a lens, and reference numeral 51 denotes a drive circuit for driving the CCD solid-state imaging devices 10 and 20. Signals read from the upper and lower two-stage amplifiers of the CCD solid-state imaging devices 10 and 20 are independently supplied to CDS (correlated double sampling) circuits 52a and 52b and ADC (analog-to-digital conversion) circuits 53a and 53b. Pass through. After the ADC is performed, the data is controlled by the memory control circuit 55, rearranged in the memory circuit 54, and the data read from the two amplifiers is combined into one image. After the combination, the image processing is performed by the circuit 56, and output as image data.
[0026]
FIG. 9 shows an example of a camera system using the CCD solid-state imaging device 30 of FIG. In FIG. 9, reference numeral 50 denotes a lens; and 51, a drive circuit for driving the CCD solid-state imaging device 30. The signals read from the four-stage amplifiers of the CCD type solid-state imaging device 30 at two upper and lower stages respectively pass through the CDS circuits 52a to 52d and the ADC circuits 53a to 53d independently. After the ADC is performed, the data is controlled by the memory control circuit 55, rearranged in the memory circuit 54, and the data read from the four amplifiers is combined into one image. After the combination, the image processing is performed by the circuit 56, and output as image data.
[0027]
【The invention's effect】
As described above, according to the present invention, since the color information of the signal charges to be read is changed for each amplifier, high-speed reading by the multi-amplifier is realized, and the image quality does not deteriorate due to variations in the amplifier characteristics.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first configuration example of a CCD solid-state imaging device according to the present invention.
FIG. 2 is a block diagram illustrating a second configuration example of the CCD solid-state imaging device according to the present invention.
FIG. 3 is a block diagram showing a third configuration example of the CCD solid-state imaging device according to the present invention.
FIG. 4 is a plan view showing an example of a transfer gate structure of the vertical CCD in FIG. 1 or FIG. 3;
FIGS. 5A and 5B are cross-sectional views taken along the lines AA 'and BB' of FIG. 4, respectively.
FIG. 6 is a timing chart showing an example of a four-phase drive pulse waveform of the transfer gate in FIGS. 4 and 5;
FIG. 7 is a diagram showing a state of reverse charge transfer in two adjacent vertical CCDs in FIG. 4;
8 is a block diagram showing a configuration example of a camera system using the CCD solid-state imaging device of FIG. 1 or FIG.
9 is a block diagram illustrating a configuration example of a camera system using the CCD solid-state imaging device in FIG.
[Explanation of symbols]
10 CCD type solid-state imaging device 11 Imaging area 12, 13 Vertical CCD
14,15 horizontal CCD
16, 17 amplifier 20 CCD solid-state imaging device 21 imaging region 22, 23 vertical CCD
24,25 horizontal CCD
26,27 amplifier 30 CCD type solid-state imaging device 31 imaging area 32,33 vertical CCD
34,35 horizontal CCD
36,37 Amplifier 38,39 Horizontal CCD
40, 41 Amplifier 50 Lens 51 Drive circuits 52a to 52d CDS circuits 53a to 53d ADC circuit 54 Memory circuit 55 Memory control circuit 56 Image processing circuit PD Photodiode (photodetector)
R, Gr, Gb, B color filters φV1 to φV4 transfer gate

Claims (5)

A CCD type solid-state imaging device in which a plurality of photodetectors are two-dimensionally arranged in an imaging region,
A color filter that is superimposed on the plurality of photodetectors and does not have the same color in the odd-numbered rows and the even-numbered rows, or has a different adjacent color even with the same color,
A first vertical CCD for transferring signal charges of the odd-numbered photodetectors of the plurality of photodetectors vertically upward or downward;
A second vertical CCD for transferring the signal charges of the even-numbered photodetectors of the plurality of photodetectors in a direction opposite to that of the first vertical CCD;
A first horizontal CCD for transferring signal charges received from the first vertical CCD in a horizontal direction;
A second horizontal CCD for transferring signal charges received from the second vertical CCD in a horizontal direction;
A first amplifier provided at the last stage of the first horizontal CCD;
A second amplifier provided at the last stage of the second horizontal CCD,
A CCD solid-state imaging device, wherein signal charges of odd-numbered columns and even-numbered columns are separately read from the first and second amplifiers, respectively. A CCD type solid-state imaging device in which a plurality of photodetectors are two-dimensionally arranged in an imaging region,
A color filter that is superimposed on the plurality of photodetectors and does not have the same color in the odd-numbered rows and the even-numbered rows, or has a different adjacent color even if the same color,
A vertical CCD for vertically transferring signal charges of the plurality of photodetectors;
A first horizontal CCD for receiving the signal charges of the photodetectors in the odd-numbered rows of the plurality of photodetectors from the vertical CCD, and transferring the received signal charges in a horizontal direction;
A second horizontal CCD for receiving the signal charges of the photodetectors in the even-numbered rows of the plurality of photodetectors from the vertical CCD, and transferring the received signal charges in a horizontal direction;
A first amplifier provided at the last stage of the first horizontal CCD;
A second amplifier provided at the last stage of the second horizontal CCD,
A CCD solid-state imaging device, wherein signal charges of odd-numbered rows and even-numbered rows are separately read from the first and second amplifiers, respectively. A CCD type solid-state imaging device in which a plurality of photodetectors are two-dimensionally arranged in an imaging region,
Overlaid on the plurality of photodetectors, the odd column and the even column do not have the same color, or even the same color has a different adjacent color, and the odd and even rows do not have the same color, Or a color filter having the same color but different adjacent colors,
A first vertical CCD for transferring signal charges of the odd-numbered photodetectors of the plurality of photodetectors vertically upward or downward;
A second vertical CCD for transferring the signal charges of the even-numbered photodetectors of the plurality of photodetectors in a direction opposite to that of the first vertical CCD;
A first horizontal CCD for receiving signal charges of the odd-numbered rows and odd-numbered photodetectors of the plurality of photodetectors from the first vertical CCD, and transferring the received signal charges in a horizontal direction; ,
A second horizontal CCD for receiving signal charges of the photodetectors in the even rows and the odd columns among the plurality of photodetectors from the first vertical CCD, and transferring the received signal charges in a horizontal direction; ,
A first amplifier provided at the last stage of the first horizontal CCD;
A second amplifier provided at the last stage of the second horizontal CCD;
A third horizontal CCD for receiving signal charges of the odd-row and even-column photodetectors of the plurality of photodetectors from the second vertical CCD, and transferring the received signal charges in a horizontal direction; ,
A fourth horizontal CCD for receiving signal charges of the even-numbered rows and even-numbered columns of the plurality of photodetectors from the second vertical CCD, and transferring the received signal charges in a horizontal direction; ,
A third amplifier provided at the last stage of the third horizontal CCD;
A fourth amplifier provided at the last stage of the fourth horizontal CCD,
A CCD type solid-state imaging device for separately reading signal charges of odd rows and odd columns, even rows and odd columns, odd rows and even columns, and even rows and even columns from the first to fourth amplifiers, respectively. element. The CCD solid-state imaging device according to claim 1, wherein
The first and second vertical CCDs are capable of progressively reading signal charges from the plurality of photodetectors, and are capable of transferring signal charges in opposite directions by the same drive pulse train. A CCD solid-state imaging device having a structure. A camera system using the CCD solid-state imaging device according to claim 1.

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