JP2007281995A - Solid-state imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging apparatus which is produced by almost the same production process for usual solid imaging apparatuses and has a plurality of resolution areas. <P>SOLUTION: The solid-state imaging apparatus is provided with a plurality of pixels 21 which are formed in an imaging area 11 of a substrate 10 in a matrix manner and include photoelectric conversion elements each, a first color filter 25A which is formed on a first area 11A of the imaging area 11 and has a prescribed color array arranged by a plurality of color areas 26, and a second color filter 25B which is formed on a second area 11B of the imaging area 11 and has the prescribed color array arranged by the plural color areas 26. The number of the pixels 21 in which each light to transmit each color area 26 of the first color filter 25A enters is more than the number of the pixels 21 in which each light to transmit each color area 26 of the second color filter 25B enters. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device, and particularly to a solid-state imaging device having a plurality of resolution regions.

  A vehicle front monitoring sensor that monitors a vehicle front using a camera and warns in advance of danger caused by a vehicle ahead, an obstacle, or the like has attracted attention for preventing a vehicle accident. The area to be monitored in the vehicle forward monitoring sensor varies greatly depending on the state of the vehicle itself such as the speed and direction of the vehicle, the traffic congestion of the road, and the state of the vehicle such as the weather.

  In order to meet such demands, for example, a method using a telephoto camera for monitoring a far distance and a wide-angle camera for monitoring a wide range, or a method for simultaneously monitoring a distant and near area using an ultra-high resolution camera is used. Yes. However, when two cameras are prepared, cost is high and downsizing is difficult. In addition, when an ultra-high resolution camera is used, there is a problem that the cost of the camera is high and that high-speed image processing becomes difficult because all areas are imaged with ultra-high resolution.

For this reason, in order to monitor both far and near by one camera without imposing a burden on image processing, the solid-state imaging device is divided into two regions and high resolution in which pixels are arranged at high density A method of providing a region and a low-resolution region arranged relatively sparsely is disclosed (see, for example, Patent Document 1). According to this method, it is possible to perform high-precision image processing on a small object far away in the high-resolution area, and to perform high-speed image processing on a relatively large object nearby in the low-resolution area.
JP-A-10-75397

  However, the conventional solid-state imaging device needs to change the formation density of photoelectric conversion elements on the substrate, and has to be manufactured by a process using a complicated mask as compared with a general solid-state imaging device. There is. For this reason, it is difficult to design and manufacture the solid-state imaging device, and the manufacturing cost of the solid-state imaging device increases.

  An object of the present invention is to solve the above-described conventional problems and to realize a solid-state imaging device having a plurality of resolution regions that can be manufactured by a manufacturing process substantially the same as that of a normal solid-state imaging device.

  In order to achieve the above object, according to the present invention, the solid-state imaging device includes a plurality of color filters each having a different number of pixels corresponding to each color region.

  A solid-state imaging device according to the present invention is formed in a matrix form in an imaging region of a substrate, each of which is formed on a plurality of pixels including photoelectric conversion elements and a first region of the imaging region, and a plurality of colors A first color filter having a predetermined color arrangement formed by arranging the areas, and a second color filter having a predetermined color arrangement formed by arranging a plurality of color areas in the second area of the imaging area. The number of pixels that are provided with a color filter and into which light transmitted through each color region of the first color filter is incident is greater than the number of pixels that are transmitted through each color region of the second color filter. It is characterized by.

  According to the solid-state imaging device of the present invention, the number of pixels on which light transmitted through each color region of the first color filter is incident is the number of pixels on which light transmitted through each color region of the second color filter is incident. Since the number is larger than the number, it is possible to change the resolution for each portion covered by each color filter by collectively handling the signals of a plurality of pixels for each color region. Further, since the resolution can be changed only by changing the size of the color region without changing the configuration and arrangement of the photoelectric conversion elements, the process is almost the same as that of a solid-state imaging device having only one normal resolution. A solid-state imaging device can be manufactured.

  The solid-state imaging device according to the present invention further includes a vertical shift register that sequentially selects a plurality of pixels in units of rows, and a signal output unit that sequentially outputs a signal charge of each pixel selected by the vertical shift register, It is preferable that the light transmitted through each color region of the color filter is incident on two or more pixels formed adjacent to each other, and the signal output unit collectively outputs signal charges for each of the two or more pixels. With such a configuration, it is possible to read an image signal in a low resolution region at high speed. Thereby, the burden of image processing is reduced, and high-speed image processing is possible.

  In this case, the solid-state imaging device preferably further includes a plurality of floating diffusion portions that are electrically connected to two or more pixels and store signal charges of the two or more pixels collectively. With such a configuration, two or more pixels covered by one color filter can be handled as one pixel in a pseudo manner, and the configuration of the output unit can be simplified. Further, higher speed driving is possible.

  In the solid-state imaging device according to the present invention, the signal output unit includes a first output unit that outputs a signal charge of each pixel formed in the first part, and a signal charge of each pixel formed in the second part. It is preferable that the 2nd output part which outputs is included. With such a configuration, a plurality of resolution areas having different resolutions can be read simultaneously, so that high-speed processing can be performed.

  In this case, the first output unit includes a first horizontal shift register that selects the pixels formed in the first portion in units of columns, and the second output unit is formed in the second portion. It is preferable that the first horizontal shift register and the second horizontal shift register are driven by different clock signals from each other. By adopting such a configuration, it is possible to realize optimum sensitivity, processing speed, and the like according to the resolution and usage of each resolution region.

  The first output unit includes a first electronic shutter circuit that controls a time for storing the signal charge of each pixel formed in the first part, and the second output unit includes the second part. The second electronic shutter circuit for controlling the time for accumulating the signal charges of each pixel formed in the second electronic shutter circuit and the second electronic shutter circuit are mutually connected. Preferably they are different. Even with such a configuration, the sensitivity and the processing speed can be optimized.

  The solid-state imaging device of the present invention further includes a vertical shift register that sequentially selects a plurality of pixels in units of rows and a horizontal shift register that sequentially selects a plurality of pixels in units of columns, and the vertical shift register and the horizontal shift register include: Each of the plurality of stages is configured so that a part of the plurality of stages can be selectively driven, and only the signal charges of the pixels selected by the vertical shift register and the horizontal shift register among the plurality of pixels are output. Is preferred. By adopting such a configuration, it is possible to process only a necessary part at high speed or to realize a zoom function.

  In the solid-state imaging device of the present invention, the predetermined color arrangement is preferably a primary color Bayer arrangement.

  According to the solid-state imaging device according to the present invention, it is possible to realize a solid-state imaging device having a plurality of resolution regions that can be manufactured by substantially the same manufacturing process as a normal solid-state imaging device.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a circuit configuration of the solid-state imaging device according to the first embodiment. As shown in FIG. 1, in the solid-state imaging device according to the present embodiment, pixels 21 are arranged in a matrix on a substrate 10 to form an imaging region 11. In FIG. 1, for simplicity of explanation, an example is shown in which the pixels 21 are arranged in 8 rows and 8 columns of A rows to H rows and 1 column to 8 columns, but the number of rows and columns is arbitrary. Can be set to Each pixel 21 may be composed of a photoelectric conversion element 22 and a switching transistor 23 as shown in FIG. In addition, an amplifier transistor, a reset transistor, a selection transistor, and the like may be included.

  The imaging area 11 is divided into two areas of a low resolution area 11A and a high resolution area 11B, and each area is covered with a first color filter 25A and a second color filter 25B, respectively. Each of the first color filter 25A and the second color filter 25B includes a plurality of primary color areas 26 of red (R), green (G), and blue (B), and the primary color Bayer array as a whole. Have. In the present embodiment, the first color filter 25A covering the low-resolution area 11A covers the four pixels 21 arranged in two rows and two columns adjacent to each other, and each color area 26 has one color area 26. The light transmitted through the light enters the four pixels 21. Therefore, a Bayer array is formed in units of 4 pixels. On the other hand, in the second color filter 25B covering the high resolution region 11B, each color region 26 covers one pixel 21, and a Bayer array is formed in units of one pixel.

  Around the imaging area 11, a vertical shift register 31 is connected to each of the horizontal selection lines 41 provided for each row of the imaging area 11 and selects the pixels 21 for each row, and a vertical signal is provided for each column. An output unit connected to each of the lines 42 and sequentially outputting the signals of the pixels 21 in the selected row is formed. The solid-state imaging device of the present embodiment is provided with two output units, a first output unit 32A that outputs a signal of the low resolution region 11A and a second output unit 32B that outputs a signal of the high resolution region 11B. Yes.

  The first output unit 32A includes a first horizontal output line 36A connected to each vertical signal line 42 via a first switch transistor 35A, and a first drive for driving each first switch transistor 35A. A horizontal shift register 33A and a first output amplifier 34A connected to the first horizontal output line 36A are provided. Similarly, the second output unit 32B includes a second horizontal shift register 33B, a second output amplifier 34B, a second switch transistor 35B, and a second horizontal output line 36B.

  Hereinafter, driving examples of the solid-state imaging device according to the present embodiment will be described with reference to the drawings. 3A and 3B show the contents of signals output from the first output unit 32A and the second output unit 32B, respectively.

  As shown in FIG. 3A, the first output unit 32A that outputs the signal of each pixel 21 arranged in the low resolution region 11A is covered by one color region 26 for each pulse of the horizontal transfer clock. The signals of the four pixels 21 are combined and output as one. Various methods for collectively outputting the signals of the four pixels 21 are conceivable. For example, a circuit in which a charge storage capacitor element is provided in each vertical signal line and horizontal output line may be used.

  FIG. 4 shows an enlarged view of the pixel A1 in the A row and the first column and the pixel B2 in the B row and the second column in FIG. As shown in FIG. 4, a capacitive element 51 is connected to the vertical signal line 42 in the first column, and a capacitive element 52 is connected to the vertical signal line 42 in the second column. A capacitive element 53 is connected to the first horizontal output line 36A.

  In this case, four pixels A1, A2, B1, and B2 are selected by the vertical shift register 31, and the charges of the pixels A1 and B1 are accumulated in the capacitor element 51 in the first column, and the charges of the pixels A2 and B2 are stored. Are stored in the capacitor elements 52 in the second column. Next, the first horizontal shift register 33A turns on the first switch transistor 35A in the first column and the first switch transistor 35A in the second column to store the first switch transistor 35A in the first column. The charge and the charge accumulated in the capacitor element 52 in the second column are accumulated in the capacitor element 53, and then output through the first output amplifier 34A. As a result, signals of four pixels in two rows and two columns from the pixel A1 to the pixel B2 can be collectively output.

  On the other hand, as shown in FIG. 3B, in the high resolution region 11B, the signal of each pixel 21 is read out line by line and sequentially output as usual.

  Therefore, the resolution in the low resolution area 11A is one fourth of the resolution of the high resolution area 11B. However, since the signals of the four pixels 21 are read out by one horizontal transfer pulse, the reading speed is quadrupled. Further, since the signals of the four pixels 21 are added together, the sensitivity is also quadrupled.

  In FIG. 3, the first horizontal shift register 33A and the second horizontal shift register 33B are driven by the same horizontal transfer clock, but as shown in FIGS. The horizontal shift register 33A and the second horizontal shift register 33B may be driven by different horizontal transfer clocks. As shown in FIGS. 5A and 5B, the frequency of the horizontal transfer clock of the first horizontal shift register 33A is set to half the frequency of the horizontal transfer clock of the second horizontal shift register 33B. The readout speed of the low resolution area 11A is twice the readout speed of the high resolution area 11B. However, the sensitivity in the low resolution region 11A can be set to 8 times the sensitivity in the high resolution region 11B.

  Conversely, if the frequency of the horizontal transfer clock of the first horizontal shift register 33A is set to twice the frequency of the horizontal transfer clock of the second horizontal shift register 33B, the sensitivity in the low resolution region 11A can be increased in the high resolution region 11B. Although the sensitivity is doubled, the frame reading speed can be increased to eight times.

  If the solid-state imaging device of this embodiment is used for a vehicle forward monitoring device, the vicinity is monitored using the low resolution region 11A, and the distant region is monitored using the high resolution region 11B, the monitoring of a large object in the vicinity is performed. It can be performed at a relatively low resolution and a small distant object can be monitored at a high resolution. For this reason, it becomes possible to reduce the burden of image processing without impairing the remote monitoring performance.

  Further, the sensitivity and the reading speed can be adjusted only by changing the frequency of the horizontal transfer clock, and it is possible to easily cope with a case where high sensitivity such as nighttime is required. Furthermore, since the resolution can be set according to the size of the color region 26, it is not necessary to change the size of the photoelectric conversion element 22 formed on the substrate 10. Therefore, it can be manufactured by almost the same process as a normal solid-state imaging device. Further, the low resolution area 11A and the high resolution area 11B can be freely assigned.

  In the solid-state imaging device according to the present embodiment, two output units are provided so that the low resolution region 11A and the high resolution region 11B can be read separately. However, the output unit may be shared. In this case, the low resolution region 11A and the high resolution region 11B may be separated when image processing is performed on the output of the solid-state imaging device. Further, although the vertical shift register 31 is shared, two vertical shift registers 31 for the low resolution region 11A and the high resolution region 11B may be provided.

  In the low resolution area 11A, one color area 26 covers four pixels 21 arranged in 2 rows and 2 columns, but n × m in n rows and m columns (where n and m are 2). It is also possible to cover the pixels. Further, the number of pixels 21 covered by one color region 26 in the high resolution region 11B is not limited to one, but may be smaller than the number of pixels 21 covered by one color region 26 in the low resolution region 11A.

  FIG. 1 shows a configuration in which the low-resolution area 11A and the high-resolution area 11B include the same number of pixels 21, but the numbers of pixels 21 included in the low-resolution area 11A and the high-resolution area 11B are respectively You may change arbitrarily as needed. Further, three or more regions having different resolutions may be provided. Furthermore, in the present embodiment, the low resolution region 11A and the high resolution region 11B are divided in the horizontal direction, but can be divided in the vertical direction.

(First modification of the first embodiment)
Below, the 1st modification of the 1st Embodiment of this invention is demonstrated with reference to drawings. FIG. 6 shows an outline of a circuit configuration in a main part of the solid-state imaging device according to the first modification of the first embodiment. The basic configuration of the solid-state imaging device of the present modification is the same as that of the solid-state device of the first embodiment. However, as shown in FIG. 6, the solid-state imaging device of this modification example is arranged in two rows and two columns adjacent to each other in the low resolution region 11 </ b> A, and the output of the four pixels 21 covered by one color region 26 is 1 Two floating diffusion (FD) sections 27 are connected.

  According to the solid-state imaging device of this modification, the signals of the four pixels 21 covered by one color region 26 are temporarily stored in the FD unit 27 and then output to the vertical signal line 42. Therefore, since the four pixels 21 connected to the FD unit 27 can be handled as a pseudo one pixel, the configuration of the first output unit 32A can be simplified. In the low-resolution region 11A of the solid-state imaging device according to this modification, the vertical signal lines 42 may be provided every other column, and the horizontal selection lines 41 may be provided every other row.

(Second modification of the first embodiment)
Below, the 2nd modification of the 1st Embodiment of this invention is demonstrated with reference to drawings. The solid-state imaging device according to this modification accumulates charges during a period from when a reset pulse (electronic shutter pulse) is applied to each vertical line (row) to when a readout pulse is applied, and outputs the accumulated charges It has a rolling shutter function. The low resolution area 11A and the high resolution area 11B are driven by different timing pulses.

  FIGS. 7A and 7B are examples of the timing of the reset pulse and the readout pulse applied to the solid-state imaging device according to this modification. FIG. 7A shows the reset pulse and the readout pulse applied to the low resolution region 11A. (B) shows the reset pulse and readout pulse applied to the high resolution region 11B.

  As shown in FIG. 8A, in the low resolution region 11A, charges are accumulated for a period of 2.5 frames after the reset pulse is applied. On the other hand, as shown in FIG. 8B, in the high resolution region 11B, the charge accumulation time from the application of the reset pulse to the application of the readout pulse is 0.5 frame. As a result, the charge accumulation time in the low resolution region 11A is five times as long as the charge accumulation time in the high resolution region 11B. Therefore, the sensitivity of the low resolution region 11A can be 20 times that of the high resolution region 11B. .

(Second Embodiment)
The second embodiment of the present invention will be described below with reference to the drawings. FIG. 8 shows an outline of a circuit configuration of the solid-state imaging device according to the second embodiment. As shown in FIG. 8, the solid-state imaging device of the present embodiment can drive only a part of the vertical shift register 31 and the second horizontal shift register 33B.

  For example, the vertical shift register 31 drives only the F and G rows, and the second horizontal shift register 33B drives only the 6th and 7th columns. Thereby, it is possible to selectively output only four pixels from the F row 6 column to the G row 7 column among the pixels of the high resolution region 11B.

  Depending on the traveling speed of the vehicle and the surrounding conditions, all information of the high resolution area 11B may not be required. In such a case, the solid-state imaging device according to the present embodiment can output only a signal of a necessary portion of the high resolution region 11B. Thereby, the burden of image processing can be reduced. Moreover, it can also be used as a zoom function for extracting only necessary portions.

  As a method of driving only a part of the vertical shift register 31 and the second horizontal shift register 33B, for example, the vertical shift register 31 and the second horizontal shift register are configured by connecting a plurality of shift register units in series, respectively. Then, only a predetermined shift register unit needs to be operated.

  In the present embodiment, an example in which pixels are selected for the high resolution area 11B is shown, but a configuration may be adopted in which some pixels can be selected for the low resolution area 11A.

  The solid-state imaging device according to the present invention can realize a solid-state imaging device having a plurality of resolution regions that can be manufactured by substantially the same manufacturing process as a normal solid-state imaging device. This is useful as a solid-state imaging device for vehicle forward monitoring.

1 is a layout diagram illustrating a circuit configuration of a solid-state imaging device according to a first embodiment of the present invention. 1 is a circuit diagram illustrating a circuit configuration of a pixel of a solid-state imaging device according to a first embodiment of the present invention. FIG. 3 is a timing diagram illustrating a driving example of the solid-state imaging device according to the first embodiment of the present invention. 1 is an enlarged circuit diagram illustrating a part of a circuit configuration of a solid-state imaging device according to a first embodiment of the present invention. FIG. 6 is a timing diagram illustrating another driving example of the solid-state imaging device according to the first embodiment of the present invention. It is a circuit diagram which shows the principal part of the solid-state imaging device which concerns on the 1st modification of the 1st Embodiment of this invention. It is a timing diagram which shows the example of a drive of the solid-state imaging device which concerns on the 2nd modification of the 1st Embodiment of this invention. It is a layout figure showing the circuit composition of the solid imaging device concerning a 2nd embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Substrate 11 Imaging area 11A Low resolution area 11B High resolution area 21 Pixel 22 Photoelectric conversion element 23 Switching transistor 25A First color filter 25B Second color filter 26 Color area 27 Floating diffusion section 31 Vertical shift register 32A First output Unit 32B second output unit 33A first horizontal shift register 33B second horizontal shift register 34A first output amplifier 34B second output amplifier 35A first switching transistor 35B second switching transistor 36A first horizontal Output line 36B Second horizontal output line 41 Horizontal selection line 42 Vertical signal line 51 Capacitor element 52 Capacitor element 53 Capacitor element

Claims (8)

A plurality of pixels formed in a matrix in the imaging region of the substrate, each including a photoelectric conversion element;
A first color filter formed on a first area of the imaging area and having a predetermined color arrangement formed by arranging a plurality of color areas;
A second color filter formed in a second area of the imaging area and having a predetermined color arrangement formed by arranging a plurality of color areas;
The number of pixels in which light transmitted through each color region of the first color filter is incident is greater than the number of pixels in which light transmitted through each color region of the second color filter is incident. Solid-state imaging device. A vertical shift register that sequentially selects the plurality of pixels in units of rows;
A signal output unit that sequentially outputs signal charges of each pixel selected by the vertical shift register;
The light transmitted through each color region of the first color filter is incident on two or more pixels formed adjacent to each other,
The solid-state imaging device according to claim 1, wherein the signal output unit collectively outputs the signal charges for each of the two or more pixels.   3. The solid according to claim 2, further comprising a plurality of floating diffusion portions, each of which is electrically connected to the two or more pixels and accumulates signal charges of the two or more pixels collectively. Imaging device. The signal output unit is
A first output unit that outputs a signal charge of each pixel formed in the first portion;
4. The solid-state imaging device according to claim 2, further comprising a second output unit configured to output a signal charge of each pixel formed in the second portion. The first output unit includes a first horizontal shift register that selects pixels formed in the first portion in units of columns,
The second output unit includes a second horizontal shift register that selects pixels formed in the second portion in units of columns,
The solid-state imaging device according to claim 4, wherein the first horizontal shift register and the second horizontal shift register are driven by different clock signals. The first output unit includes a first electronic shutter circuit that controls a time for accumulating signal charges of each pixel formed in the first portion,
The second output unit includes a second electronic shutter circuit that controls a time for storing the signal charge of each pixel formed in the second portion,
6. The solid-state imaging device according to claim 4, wherein the second electronic shutter circuit and the second electronic shutter circuit have different times for storing the signal charges. A vertical shift register that sequentially selects the plurality of pixels in units of rows;
A horizontal shift register that sequentially selects the plurality of pixels in units of columns;
Each of the vertical shift register and the horizontal shift register includes a plurality of stages and is configured to selectively drive a part of the plurality of stages.
2. The solid-state imaging device according to claim 1, wherein only a signal charge of a pixel selected by the vertical shift register and the horizontal shift register among the plurality of pixels is output. The solid-state imaging device according to claim 1, wherein the predetermined color array is a primary color Bayer array.

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