JPH11298910A - Imaging device and image-pickup unit using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To pick up both a color image and a black/white image by the same imaging device and to pickup the black/white image at a high speed. SOLUTION: Color filters are arranged according to the RGB Bayer arrangement, and a spectral characteristics of the color filters is selected, so that outputs of color components R, G, B in 4 pixels in each color pixel group 6 in a color pixel matrix consisting of 2m-sets of pixels in the horizontal direction and 2n-sets of pixels in the vertical direction are R:G:B=0.299:0.587:0.144. A black/white image consisting of m×n pixels is obtained directly by outputting the sum of charges of the 4 pixels as an output signal. In this case, conventional drive control is applied to the same image-pickup element 10 to obtain a color image. Furthermore, drive control to sum 4 pixels in the color pixel group 6 is applied to the image-pickup element 10 to obtain a black/white image with high sensitivity, and this drive control is selectable.

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 picking up a color image and a high-resolution monochrome image, and an image pickup device using the same. .

[0002]

2. Description of the Related Art Conventionally, color has been transmitted through primary color filters of red (R), green (G), and blue (G) or complementary color filters of cyan (C), magenta (M), and yellow (Y). When a monochrome image is to be obtained using an image pickup device that captures an image, a predetermined operation for converting a color system into element values of a primary color system or a complementary color system for each pixel constituting the obtained color image. The ceremony was given. That is, as in the case of obtaining a color image, this image sensor outputs an image signal, and the output result is subjected to a predetermined conversion formula by a signal processing circuit or signal processing software to be converted to a monochrome image. And output it.

For example, when a color image composed of R, G, and B elements is converted into a black and white image, the luminance is converted into a luminance Y of the YIQ color system adopted by the NTSC system. This conversion is

## EQU00001 ## Y = 0.299R + 0.587G + 0.114B, and was performed by a signal processing circuit or signal processing software.

[0004]

However, when the signal processing circuit converts the above-mentioned color image into a black and white image, the color image pickup signal is once subjected to A / D conversion, converted into a digital signal, and temporarily stored in a memory. In addition to the necessity, it takes time to perform a signal processing operation of a signal processing circuit for converting a color image into a black and white image or a signal processing operation by signal processing software, so that a black and white image cannot be output at high speed. The point is warm.

Further, in the case of an electronic camera, a black-and-white image cannot be output at a high speed. As a result, there has been a problem in that the image capturing interval of the black-and-white image is limited and high-speed continuous shooting cannot be performed.

Therefore, the present invention eliminates such a problem,
It is an object of the present invention to provide an image sensor capable of capturing both a color image and a black-and-white image with the same image sensor and capable of capturing a black-and-white image at high speed, and an image pickup apparatus using the same.

[0007]

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. A color pixel matrix including a green (G) color filter for 2a pixels, a blue (B) color filter for a pixel, and a red (R) color filter for other a pixels; , And sequentially read out.

[0008] In the first invention, 4a adjacent vertically and horizontally
Since the pixels are added and output, not only an image pickup signal for color image processing but also a monochrome image signal such as a luminance signal can be directly output on the image pickup element by the same image pickup element.

According to a second aspect of the present invention, there are provided a plurality of pixels each having a photoelectric conversion element and arranged in a matrix.
A color pixel matrix including a color filter of green (G) for a pixel, blue (B) for a pixel, and red (R) for another a pixel is provided.
an image pickup element capable of sequentially reading out by adding the electric charge of the pixel a;
A driving circuit capable of supplying a driving signal for adding and reading out the electric charge of the pixel.

In the second invention, since the image pickup device according to the first invention and the driving circuit for adding and outputting the 4a pixels vertically and horizontally adjacent to the image pickup device are provided, for example, Such a monochrome image signal can be directly obtained from the image sensor, and there is no need to perform signal processing for converting a signal corresponding to a color image to a signal corresponding to a monochrome image. , The time required for outputting a black-and-white image can be reduced, the shooting interval can be shortened, and high-speed continuous shooting can be performed.

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.

In the third invention, when a black and white image is obtained,
Since the amount of charge increases as compared with the case of outputting a color image, a high-sensitivity image can be obtained.

In a fourth aspect based on the third aspect, the mode is switched between a mode in which the m horizontal and n vertical pixel signals are read out and a mode in which 2 m horizontal and 2n vertical pixels are read out without addition. Means.

According to the fourth aspect, the switching means provides a mode for reading without adding, for example, corresponding to color image output, and a mode for reading, for example, monochrome image output.
Since the mode can be switched to the addition and reading mode, a multi-function imaging device can be realized using the same imaging device, and a flexible imaging device can be realized.

According to a fifth aspect of the present invention, in the second aspect, a is a natural number, and the luminance signals are read out by adding the charges of the 4a pixels adjacent to each other in the upper, lower, left, and right directions. As a result, a black-and-white image corresponding to the luminance signal can be output with high sensitivity, and since there is no need to generate a luminance signal by signal processing operation, high-speed output is possible, and high-speed continuous shooting can be realized.

According to a sixth aspect, in the second aspect, when the color temperature of the light source is different from the reference color temperature of the light source due to the shooting environment, a is set to a natural number by using a color correction filter. , 4 adjacent to the top, bottom, left and right
It is characterized in that the ratio of each color signal of the a-pixel is corrected and an accurate luminance signal can be read. As a result, an accurate luminance signal corresponding to an appropriate color temperature can be obtained, and as a result, an accurate black-and-white image can be obtained.

[0017]

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 sensor 10 constitutes a color pixel matrix in which 2m pixels 1 in a horizontal direction (row direction) and 2n pixels in a vertical direction (column direction) are arranged. The color pixel matrix has R, G, and B color pixels arranged in an RGB Bayer array, and includes a plurality of m color pixel groups 6 in the horizontal direction and n color pixel groups in the vertical direction. One color pixel group 6 in the RGB Bayer arrangement is composed of four pixels 1 of 2 × 2 pixels. For example, G,
Each color pixel of R is adjacent to one row and two columns, and each color pixel of B is two rows and one column. Each of these pixels 1 as a photoelectric conversion element such as a photodiode functions as one of R, G, and B color pixels. This function is to apply each R, G, and B light to the upper surface of each pixel 1. A color filter for transmission is provided. Therefore, for example, the pixel 1 in the first row and the first column transmits only G (green) light,
Only the light component is received and photoelectrically converted. Note that m and n are natural numbers.

When the image pickup device 10 picks up a color image, the electric charges accumulated in the pixels 1 in each vertical direction are output in synchronization with the vertical transfer circuit 2, and the electric charges output to the vertical transfer circuit 2 The charges corresponding to the pixels 1 in the horizontal direction are sequentially transferred one stage at a time to the horizontal transfer circuit 3 in synchronization with the horizontal transfer circuit 3. The horizontal transfer circuit 3 outputs the charges corresponding to the pixels 1 in the horizontal direction to the output amplifier 4 one stage at a time. Transferred and output as an output signal 5 via
All the charges accumulated in all the pixels 1 are swept out. This allows
A series of charges output as an output signal correspond to pixels corresponding to B, G, B, G,... In the first stage, and to pixels G, R, G, R,. The charge corresponding to the pixels B, G, B, G,... Is repeatedly output in the next stage, and the charge corresponding to the pixels G, R, G, R,. Because of the regularity,
R, G, and B color images corresponding to the arrangement of the color pixel groups 6 are generated.

In particular, such an RGB Bayer arrangement facilitates conversion from the RGB color system to the YIQ color system adopted by the NTSC system. That is, Y
The IQ color system includes a luminance Y corresponding to a black and white image, a color difference I,
Q, and has the following conversion relationship with the RGB color system. That is,

## EQU2 ## Y = 0.299R + 0.587G + 0.144B I = 0.596R-0.274G-0.322B Q = 0.221R-0.522G + 0.311B, and the color differences I and Q are as follows. Can be transformed into

I = 0.596 (RG) +0.322 (GB) Q = 0.221 (RG) −0.311 (GB), so that R, G, and G If the difference between B and B can be calculated, the color differences I and Q can be easily obtained. Where RG
In the B-Bayer arrangement, B and G and G and R are adjacent to each other in the color pixel group 6 and are transferred and output adjacently.
The above calculation can be easily performed.

On the other hand, when the image pickup device 10 picks up a black-and-white image which is a feature of the present invention, as shown in FIG. The output signal 10 is added as an output signal 5, and the added charge is output as an output signal 5 in a form of being sequentially transferred in a line.

Further, for four pixels in each color pixel group 6, the output of each color component of one R pixel: two G pixels: one B pixel is 0.299: 0.5, respectively.
The spectral characteristics of each of the R, G, and B color filters are set so as to be 87: 0.144. Thereby, the electric charge added by each color pixel group 6 corresponds to the luminance Y of the YIQ color system, and the output signal 5 from the image sensor 10 outputs a luminance (Y) signal in the arrangement of each color pixel group 6. That is, the addition pixels 8 in the mxn matrix indicate the respective pixels of the monochrome image (see FIG. 3).

In this case, the charge amount of the addition pixel 8 increases, so that a monochrome image with high sensitivity can be obtained.

Here, there are the following addition modes on the image sensor 10. First, two vertical pixels (G and B or R and G) in the color pixel group 6 are added on the vertical transfer circuit 2, and the added pixels are further added on the output amplifier 4. It is like that.

Second, two pixels in one vertical column in the color pixel group 6 are added when transferred by the horizontal transfer circuit 3, and the added pixels are further added on the output amplifier 4. Things.

Third, electric charges of four pixels are output only to the vertical transfer circuit 2 existing between two vertical columns of four pixels in the color pixel group 6, and one horizontal row of pixels is output on the vertical transfer circuit 2. Pixels are added, and one vertical column of pixels is added on the vertical transfer circuit 2.

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
At the stage of output, the four pixels in each color pixel group 6 are added, and a virtual added pixel 8 corresponding to a luminance signal is directly output as the output signal 5. A black-and-white image can be immediately obtained as it is without performing calculations for the R, G, and B color components thereafter.

The above-described color image matrix in the image sensor 10 has a Bayer arrangement.
The color components R, G, B in each color pixel group 6 are not limited thereto.
The arrangement of the pixels may be arbitrary.

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, and an amplification type solid-state image pickup device that sweeps out the electric charge accumulated in each pixel 1 by switching processing. 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 with reference to FIGS. FIG. 4 is a block diagram showing a configuration of an electronic camera using the image sensor 10. In FIG. 4, an image pickup device 10 includes a subject 2 input through an optical system 11.
8 is converted 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 for modulating 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 controls the whole of the above-mentioned components constituted by, for example, a microprocessor.

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

The image sensor 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 imaging device 10 is directly driven from P14 via the timing generator 20. The vertical transfer pulse for vertical charge transfer is input to the timing generator 20, and drives the image sensor 10 with a signal that has been converted in voltage via the drive unit 19.

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, the photographing mode changeover switch of the operation unit 25 switches the photographing mode (color mode) for the color image and the photographing mode (black and white mode) for the black and white image. When the color mode is instructed, the CPU 21 instructs the DSP 14 that the color mode has been set, and the DSP 14 sets the four pixels in each color pixel group 6 in the horizontal pixel group according to the normal charge transfer control. Are generated, a driving timing pulse for sequentially transferring the image signals one by one is generated, and the image sensor 10 is driven.
The output signal input via the A / D converter 13 is subjected to signal processing corresponding to color image output.

The CPU 21 also performs instruction control for other units corresponding to the color mode. On the other hand, when the monochrome mode is instructed, the CPU 21 instructs the DSP 14 that the monochrome mode has been set, and the DSP 14
A drive timing pulse for adding the four pixels in each color pixel group 6 is generated to drive the image sensor, and the output signal input through the A / D converter 13 is converted to a signal corresponding to a monochrome image output. Perform processing. Also, CPU2
1 also performs instruction control for other units corresponding to the monochrome mode. However, in the case of the monochrome mode, only the luminance signal Y needs to be processed.
The load on the subsequent processing of the signal output from 4 is smaller than in the color mode.

In this electronic camera, the color mode and the monochrome mode are manually switched through the operation unit 25. However, the present invention is not limited to this. A control for automatic switching may be performed. For example, when the photographing environment is too dark to obtain a sufficient amount of light, the mode may be switched to the high-sensitivity monochrome mode, and when the photographing environment is bright, the mode may be switched to the light resolution color mode.

When the color temperature of the light source is different from the reference color temperature depending on the photographing environment, the color temperature may be corrected using a color correction filter. In this case, there is almost no influence on the processing load of the color correction by the DSP 14 when the color mode is set.

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 photographing mode switch 32 is a switch for switching between a color mode and a black and white mode, and the mode state is displayed on the LCD 34. The command dial 33 is a dial used for setting operations such as a shutter speed and an aperture value.
34.

[0052]

As described above in detail, according to the first aspect of the present invention, the output signals corresponding to the color image and the black and white image can be directly output by the same image sensor, so that the subsequent processing load and processing time Can be reduced, and a black-and-white image has an effect that a high-sensitivity signal output is obtained because charges are added.

In the second to sixth inventions, since the image pickup device of the first invention is used, a color image can be obtained by the same image pickup device, and an arithmetic processing for outputting a black and white image can be performed. The load and calculation processing time can be reduced. As a result, the interval between continuous shooting shutters for black-and-white images can be significantly reduced, and an effect that a high-speed continuous shooting function for black-and-white images can be realized. For example, the shutter interval, which conventionally took 6 to 7 seconds, can be reduced to 2 seconds.

Further, since a black-and-white image is a high-sensitivity image, there is an effect that an appropriate image can be obtained even in a dark shooting environment.

[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 a principle of obtaining a black and white image by adding a color pixel matrix.

FIG. 3 is an explanatory diagram showing a black-and-white 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 (6)

[Claims] 1. A plurality of pixels each having a photoelectric conversion element and arranged in a matrix and when a is a natural number, 2a pixels are green (G), a Blue (B) for pixel, red (R) for other a pixels
An image pickup device comprising a color pixel matrix configured by mounting the above color filters, and by adding the charges of the 4a pixels adjacent in the upper, lower, left, and right directions and sequentially reading them out. 2. A plurality of pixels each having a photoelectric conversion element and arranged in a matrix, and when a is a natural number, 2a pixels are green (G), a Blue (B) for pixel, red (R) for other a pixels
An image pickup device including a color pixel matrix configured by mounting color filters of the above, and capable of sequentially reading out by adding charges of the 4a pixels adjacent to the top, bottom, left and right, and adjacent to the image pickup device in the top, bottom, left, and right directions A driving circuit capable of supplying a driving signal to add and read out the charges of the four pixels. 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 in which m horizontal and n vertical pixel signals are read out and a mode in which 2m horizontal and 2n vertical pixels are read out without adding them. Item 4. The imaging device according to Item 3. 5. The imaging device according to claim 2, wherein a is a natural number, and charges of the 4a pixels adjacent in the vertical and horizontal directions are added to read out a luminance signal. 6. When a color temperature of a light source is different from a reference color temperature of a light source due to a shooting environment, by using a color correction filter, when a is a natural number, 4a pixels adjacent to the upper, lower, left, and right sides are used. 3. The imaging apparatus according to claim 2, wherein a ratio of each color signal is corrected, and an accurate luminance signal can be read.