JPH11298800A - Image-pickup element and image-pickup device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-pickup element and an image-pickup device using this which is capable of improving a dynamic range with high sensitivity. SOLUTION: From a color pixel matrix provided with 2m-number of pixels in a horizontal direction and 2n-number of pixels in a vertical direction, the electric charges of four pixels within a group of respective color pixels 6 which are four pixel units with the color filter of the same color component are added on the image-pickup element 10 and outputted. In addition, the reading of one unit of each pixel and the processing of adding and reading by the unit of the group 6 are switch-controlled to switch-output the color image of high resolution and that of quadrupled high sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device and an image pickup device using the same, and more particularly to an image pickup device capable of appropriately switching and outputting a high-sensitivity and high-resolution image pickup signal and an image pickup device using the same.

[0002]

2. Description of the Related Art Conventionally, in a color electronic camera using an IT-CCD, there is a type in which electric charges accumulated in vertically arranged pixels are added to double the electric charge signal amount. Is being improved.

[0003]

However, while maintaining the resolution of a certain level or more using primary color filters of red (R), green (G), and blue (G), the charge of the pixel is added to the sensitivity. In order to improve the number of pixels, it is necessary to further increase the number of pixels.On the other hand, when the number of pixels is increased, the charge handled by each pixel is reduced due to restrictions on the layout of the pixel and the charge transfer path. There has been a problem that the dynamic range of the photoelectric conversion is reduced as well as the dynamic range.

Therefore, the present invention eliminates such a problem,
It is an object of the present invention to provide an imaging device capable of improving a dynamic range with high sensitivity and an imaging device using the same.

[0005]

According to a first aspect of the present invention, a plurality of pixels each having a photoelectric conversion element and arranged in a matrix are provided, and a color filter of the same color is mounted for every predetermined number of adjacent pixels. It is characterized in that it comprises a color pixel matrix having a configuration, and charges can be sequentially read out by adding the charges of the predetermined number of adjacent pixels. As a result, a predetermined number of times of electric charges are added, so that the image sensor can be used as an imaging device capable of improving sensitivity and dynamic range.

According to a second aspect of the present invention, there is provided a color pixel matrix comprising a plurality of pixels each having a photoelectric conversion element and arranged in a matrix, and having a predetermined number of adjacent pixels mounted with a color filter of the same color. An image pickup device having a predetermined number of pixels adjacent to each other and capable of sequentially reading the same; and a driving signal for adding and sequentially reading the charges of the predetermined number of adjacent pixels to the image pickup device. And a driving circuit capable of supplying
Thereby, a color image with improved sensitivity and dynamic range can be obtained.

A third invention is the second invention, wherein m,
When n and b are natural numbers, the color pixel matrix includes bm horizontal pixels and bn vertical pixels. The driving circuit adds and reads the charges of the adjacent 2b pixels, and reads out the m horizontal and n vertical pixels. The pixel signal can be read out. As a result, a color image having four times higher sensitivity and a dynamic range can be obtained.

In a fourth aspect based on the third aspect, the mode is switched between a mode in which the horizontal m and vertical n pixel signals are read out and a mode in which horizontal 2m and vertical 2n pixels are read out without adding them. Means is provided. As a result, a color image having four times higher sensitivity and a dynamic range and a high-resolution color image can be switched and output.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram illustrating a configuration of an imaging device according to an embodiment of the present invention. The image pickup device 10 forms a color pixel matrix in which a plurality of 2m pixels 1 in a horizontal direction (row direction) and 2n pixels in a vertical direction (column direction) are arranged. The color components of all the pixels in the color pixel group 6 composed of four adjacent 2 × 2 pixels are the same,
It is composed of m × n color pixel groups 6.

When the color pixel matrix is viewed in units of six (m × n) color pixel groups, an RGB Bayer arrangement is obtained. For example, a 2m × 2n color pixel matrix M
M (1,1), M (1,2), M (2,1),
Each of the four pixels of M (2, 2) is arranged as a pixel having a color filter of a color component G, and M (1, 3), M
The four pixels of (1, 4), M (2, 3), and M (2, 4) are arranged as pixels having a color filter of a color component R, and M (3, 1), M (3, 2), M (4,1), M
Each of the four pixels (4, 2) is arranged as a pixel having a color filter of a color component B, and M (3, 3), M
The four pixels (3, 4), M (4, 3), and M (4, 4) are arranged as pixels having a color filter of a color component G.

These pixels 1 as photoelectric conversion elements such as photodiodes function as pixels of R, G, and B color components, respectively.
The above-described color filter that transmits light of G and B color components is provided. Therefore, for example, the pixel 1 of the color pixel matrix M (1, 1) transmits, receives, and photoelectrically converts only light of the G (green) color component. Note that m and n are natural numbers.

Here, as shown in FIG. 2, the electric charge accumulated in each of the four pixels in each color pixel group 6 is
The added signal is output as an output signal 5 in a form in which the added charges are sequentially transferred side by side.

As a result, as shown in FIG. 3, it is possible to obtain a pixel arrangement of an RGB Bayer array with each color pixel group 6 as a unit.

There are the following addition modes on the image pickup device 10. The first is that two pixels 1a, 1b or two pixels 1
c and 1d are added on the vertical transfer circuit 2, and the added pixels are added on the output amplifier 4.

Second, when two pixels 1a, 1b or two pixels 1c, 1d in one vertical column in the color pixel group 6 are sequentially transferred to the vertical transfer circuit 2 and transferred by the horizontal transfer circuit 3, The two pixels of one vertical column are added on the horizontal transfer circuit 3 and the added pixels are further added on the output amplifier 4.

The third is between two vertical columns of four pixels in the color pixel group 6 (between the pixels 1a and 1b and the pixels 1c and 1d).
, The electric charge of each of the four pixels is output only to the vertical transfer circuit 2 existing in the vertical transfer circuit 2, and the two pixels 1a and 1c
Are added, and the added pixels in the vertical column are added on the vertical transfer circuit 2.

Fourth, two pixels 1a, 1b or two pixels 1a in one vertical column in the color pixel group 6 are arranged.
c and 1d are added on the vertical transfer circuit 2 and output as an output signal 5 as it is.

Fifth, when two pixels 1a, 1b or two pixels 1c, 1d in one vertical column in the color pixel group 6 are sequentially transferred to the vertical transfer circuit 2, and are transferred by the horizontal transfer circuit 3. , Two pixels of one column each are added on the horizontal transfer circuit 3 and output as it is as an output signal.

Sixth, the four pixels in the color pixel group 6 are sequentially transferred vertically via the vertical transfer circuit 2 and then sequentially transferred horizontally via the horizontal transfer circuit 3. Only two pixels 1a and 1c or two pixels 1b and 1d in one horizontal row in the group 6 are added and output as an output signal 5 as it is.

Such addition on the image sensor 10 can be easily achieved by controlling the driving of the charge transfer to the image sensor 10.

As described above, the output signal 5 on the image sensor 10
When the four pixels in each color pixel group 6 are added at the stage of output as, the charge amount for the R, G, and B color components in each color pixel group 6 is four times the charge amount of a single pixel, 2
When the pixels are added, the charge amount is doubled, the sensitivity is improved, and the dynamic range of photoelectric conversion can be improved.

Each of the color pixel groups 6 in the color image matrix in the image pickup device 10 described above is a 2 × 2 4
However, the present invention is not limited to this. Two pixels of 1 × 2, 3 × 3
, An arbitrary number, such as 9 pixels, 3 × 2, and 6 pixels, may be configured in any arrangement.

Further, the above-described image pickup device 10 has been described on the assumption that the CCD solid-state image pickup device is used. However, the present invention is not limited to this. Obviously, this is applicable.

Next, an electronic camera as an image pickup apparatus using the image pickup device 10 shown in FIG. 1 will be described. FIG.
FIG. 2 is a block diagram illustrating a configuration of an electronic camera using the imaging device 10. In FIG. 4, an image sensor 10 includes an optical system 11
To convert the image of the subject 28 input through the electronic device into an electric signal. This optical system 11 has an infrared cut filter.

The CDS / AGC circuit 12 includes the image pickup device 10
Is subjected to a CDS function for reducing noise components by correlated double sampling or the like and an AGC function for performing automatic amplification according to sensitivity, and outputs the signal to the A / D converter 13.

The A / D converter 13 converts an analog signal from the CDS / AGC circuit 12 into a 10-bit digital signal and outputs the digital signal to a digital signal processing unit (DSP) 14. It is needless to say that the A / D converter 13 may convert the analog signal from the CDS / AGC circuit 12 into a digital signal of 10 bits or more.

The DSP 14 performs image interpolation processing, black level adjustment, gamma correction, knee correction, and the like on the input 10-bit digital data, and converts the 10-bit digital data into 8-bit data. A signal processing circuit that performs processing such as matrix and contour correction, and performs processing such as generation of 16-bit digital data composed of 8-bit luminance components and 8-bit color difference components, and is a one-chip LSI for digital signal processing. is there. Also, D
The SP 14 also performs a drive timing pulse generation process for the image sensor 10.

The compression / decompression unit 15 performs compression / decompression processing based on the JPEG standard, which is an international standard for still images, and specifically includes discrete cosine transform (DCT) and inverse DCT.
T, a one-chip decoder that performs logical processing such as Huffman encoding / decoding. Further, the compression / decompression unit 15 takes in and accesses data to and from the buffer memory 16 and also refreshes the buffer memory 16 composed of a DRAM.

The buffer memory 16 includes a compression / decompression unit 15
Is a memory for temporarily storing image data of one frame before compression, and is composed of a DRAM as described above.

The SRAM 22 adds header information as a JPEG file to the image data compressed by the compression / decompression unit 15, and has a function as a buffer memory before storage in the flash memory 26.

The flash memory 26 is a nonvolatile memory for finally storing an image file which is a JPEG file to which header information has been added.

The external interface 27 is an interface for transferring data between an external processing device such as a personal computer and the electronic camera body.

The digital encoder 17 is a chip that modulates digital data into an analog video signal.

The display 18 is realized by an LCD or the like, and displays and outputs a video signal generated by the digital encoder 17.

The speedlight section 24 has a function of independently controlling external light control. That is, the speedlight unit 2
In 4, light emission, charge, and the like are controlled by a CPU 21 described later, and light emission amount control is performed by external light control by the speedlight unit alone.

The LCD 23 has various shooting modes, remaining frames,
The status of erase (erase), battery detection, etc. is displayed on the LCD.

The CPU 21 is constituted by, for example, a microprocessor and controls the above-described units as a whole.

The timing generator 20 generates various pulses for driving the image pickup device 10 and various timing pulses for the above-described respective units.

The image pickup device 10 is controlled by the drive timing pulse from the DSP 14 described above. The horizontal transfer pulse for horizontal charge transfer of the image sensor 10 is DS
The image pickup device 10 is directly driven from P 14 via the timing generator 20, and a vertical transfer pulse for vertical charge transfer is input to the timing generator 20, and the image pickup device is driven by a signal which is voltage-converted via the drive unit 19. 10 is driven.

Here, the operation unit 25 includes a photographing mode changeover switch for switching various photographing modes and a command dial for setting various commands.

That is, each pixel 1 of the color pixel matrix is operated by the photographing mode changeover switch of the operation unit 25.
A high-resolution mode for outputting a color image of a color pixel group, a high-sensitivity mode for outputting a color image of six color pixel groups,
An instruction to switch between a high-resolution mode and a high-sensitivity mode is automatically given in accordance with an imaging environment such as luminance.

When the high resolution mode is designated, the CPU
Numeral 21 indicates that the high resolution mode has been set to the DSP 14, and the DSP 14 sequentially transfers the four pixels in each color pixel group 6 one by one in the horizontal direction according to the normal charge transfer control. A drive timing pulse is generated to drive the image pickup device 10, and an output signal input via the A / D converter 13 is subjected to signal processing corresponding to a color image output. Further, the CPU 21 also performs instruction control for other units corresponding to the high resolution mode.

When the high sensitivity mode is instructed, the CPU 2
1 indicates that the high-sensitivity mode has been set to the DSP 14, the DSP 14 generates a drive timing pulse for adding the four pixels in each color pixel group 6, drives the image sensor, and sets the A / A The signal processing is performed on the output signal input via the D converter 13. Also, CP
U21 also performs instruction control for other units corresponding to the high sensitivity mode.

When the auto mode is instructed, the CPU 2
1 instructs the DSP 14 that the auto mode has been set, the DSP 14 generates a drive timing pulse in the image sensor 10 with, for example, the high resolution mode as a default mode, and based on an output signal from the image sensor 10 The luminance component is monitored and it is determined whether or not the luminance component is equal to or less than a predetermined value. If the determination result is equal to or less than the predetermined value, the mode is switched to the high sensitivity mode. If not, the high resolution mode is maintained as it is. .

When the output signal is obtained by adding only two pixels among the four pixels in each color pixel group 6, high sensitivity by adding four pixels and processing by only each pixel are performed. Since an intermediate high sensitivity and a high resolution can be obtained, the intermediate mode may be added, or the intermediate mode may be added as a switching target of the auto mode.

FIG. 5 is a plan view of the above-described electronic camera. The electronic camera body 31 has a shooting mode changeover switch 32, a command dial 33, an LCD 3
4 and a release switch 35. The shooting mode changeover switch 32, command dial 33, and release switch 35 are part of the operation unit 25 in FIG. 4, and the LCD 34 corresponds to the LCD 23 in FIG. The shooting mode changeover switch 32 is a switch for switching among three modes of a high resolution mode, a high sensitivity mode, and an auto mode.
Will be displayed within The command dial 33 is a dial used for setting operations such as a shutter speed and an aperture value, and the result of setting is displayed on the LCD 34.

As described above, in the electronic camera shown in FIG. 4, a high-resolution color image can be obtained using the same image pickup device 10, and a high-sensitivity color image having a wide dynamic range can be obtained. Further, since the switching can be performed manually and automatically, flexible color image capturing can be performed.

[0048]

As described above in detail, according to the first aspect, a color filter of the same color is mounted for each of a predetermined number of adjacent pixels, and charges of the predetermined number of pixels are added and sequentially read out. As a result, the read charge is increased by a predetermined number of times, and as a result, there is an effect that an imaging device with high sensitivity and improved dynamic range can be obtained.

Further, in the second to fourth inventions, control is performed by adding and reading out charges of a predetermined number of adjacent pixels from the image pickup device of the first invention. Can be obtained.

Further, switching between a high-resolution color image without addition and a high-sensitivity color image with addition can be performed, and automatic switching in accordance with the photographing environment is also performed. Can be obtained appropriately.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an imaging device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the principle of obtaining a high-sensitivity image by adding a color pixel matrix.

FIG. 3 is an explanatory diagram showing a high-sensitivity image obtained by adding a color pixel matrix.

FIG. 4 is a block diagram showing a configuration of an electronic camera using the imaging device shown in FIG.

5 is a schematic plan view of the electronic camera shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 pixel 2 vertical transfer circuit 3 horizontal transfer circuit 4 output amplifier 5 output signal 6 color pixel group 8 addition pixel 10 imaging device 14 digital signal processing unit (DSP) 19 drive unit 20 timing generator 21 CPU 25 operation unit

Claims (4)

[Claims] 1. A color pixel matrix comprising a plurality of pixels each having a photoelectric conversion element and arranged in a matrix, and including a color filter of the same color for every predetermined number of adjacent pixels, An imaging device wherein charges of a predetermined number of adjacent pixels are added to enable sequential reading. 2. A color pixel matrix comprising a plurality of pixels each having a photoelectric conversion element and arranged in a matrix, and including a color filter of the same color for every predetermined number of adjacent pixels, An imaging element capable of sequentially reading out by adding charges of a predetermined number of adjacent pixels; and a driving signal capable of adding a charge of the predetermined number of adjacent pixels and sequentially reading out the image pickup element. An imaging device, comprising: a driving circuit. 3. When m, n, and b are natural numbers, the color pixel matrix includes bm pixels in the horizontal direction and bn pixels in the vertical direction. The imaging device according to claim 2, wherein m and n vertical pixel signals can be read. 4. A means for switching between a mode for reading m horizontal pixel signals and n vertical pixel signals and a mode for reading 2m horizontal and 2n vertical pixels without adding them. Item 4. The imaging device according to Item 3.