JPH05344275A - Solid-state color image pickup device - Google Patents

Abstract

PURPOSE:To provide a solid-state color image pickup device where a color linear image sensor picks up a color image and there is no level difference in the image pickup outputs of respective colors and there is no mixed colors. CONSTITUTION:A photoelectric conversion part 1 for one line, in which color filters are sequentially disposed, the shift register 3 or point sequential output, from which an image pickup charge obtained by the photoelectronic conversion part 1 is read, and a shift gate 2 which is provided between the photoelectronic conversion part 1 and the shift register 3 and which is gate-controlled by colors are provided for a light-receiving part. The image pickup charges obtained by the photoelectronic conversion part 1 is read by the shift gate 2 by the individual colors through the shift gate 2 and they are lineally and sequentially outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state color image pickup device for performing color image pickup by a linear image sensor having a photoelectric conversion portion for one line.

[0002]

2. Description of the Related Art Conventionally, linear image sensors have been
It is widely used as an image input unit in image transmission devices and electronic copying devices. In the image input section of a color copy or a color image scanner, a light source switching method that sequentially switches light sources or a filter switching method that sequentially switches color filters to be inserted in the optical path is adopted, and a color is detected using a black and white linear image sensor. I was taking an image. Further, a solid-state color image pickup device for performing color image pickup using a color linear image sensor having a color filter on-chip is also being put into practical use.

As a conventional color linear image sensor, as shown in FIG. 5, photoelectric conversion units 51R,
51G, 51B and shift registers 52R, 52G, 52
A first structure in which B is arranged in parallel, and a second structure including a photoelectric conversion unit 61 and a shift register 62 for one line in which color filters R, G, and B are sequentially arranged in a light receiving unit as shown in FIG. The structure, and further, as shown in FIG.
A photoelectric conversion unit 71 for one line in which G and B are sequentially arranged and a shift register 72 for reading the imaging charge for each color
A third structure having R, 72G, and 72B arranged in parallel is known.

[0004]

By the way, in the color linear image sensor having the first and third structures described above,
Since the shift registers are arranged side by side to read out the image-capturing charges for each color, there is a problem that a level difference occurs in the image-capturing output of each color due to the non-uniformity of the characteristics of each shift register. .. Further, in the color linear image sensor having the second structure, since the image pickup output of each color is read through the common shift register, there is no level difference in the image pickup output of each color. Since the image-capturing charges are dot-sequentially output via the common shift register, there is a problem that color mixture occurs due to the transfer residue of the image-capturing charges in each stage.

Therefore, in view of the problems in the conventional color linear image sensor as described above, the present invention performs color image pickup by the linear image sensor, and the level difference due to the characteristic of the shift register in the image pickup output of each color. An object of the present invention is to provide a solid-state color image pickup device that does not cause color mixture and does not cause color mixture.

[0006]

In order to solve the above-mentioned problems, a solid-state color image pickup device according to the present invention includes a photoelectric conversion portion for one line in which a color filter is sequentially arranged in a light receiving portion,
The photoelectric conversion unit includes a shift register for dot-sequential output from which the imaging charges obtained by the photoelectric conversion unit are read, and a shift gate provided between the photoelectric conversion unit and the shift register and gate-controlled for each color. It is characterized in that the image-capturing charges obtained by the above are read out to the shift register for each color through the shift gate and are output line-sequentially.

In the solid-state color image pickup device according to the present invention, the shift register may have a transfer stage number that is ⅓ of the number of pixels of the photoelectric conversion unit. The shift register may have the same number of transfer stages as the number of pixels of the photoelectric conversion unit, and may be supplied with a reset pulse thinned to 1/3 of the transfer clock.

[0008]

In the solid-state color image pickup device according to the present invention, the image pickup charges obtained by the photoelectric conversion portion for one line in which the color filters are sequentially arranged in the light receiving portion are shifted through the shift gates which are gate-controlled for each color. , And output line-sequentially.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a solid-state color image pickup device according to the present invention will be described in detail below with reference to the drawings. The image pickup apparatus according to the present invention is configured, for example, as shown in FIG.

The solid-state color image pickup device of the first embodiment shown in FIG. 1 comprises a photoelectric conversion section 1, a shift gate 2, a shift register 3 and an output buffer 4.

In the photoelectric conversion section 1, the light receiving elements 1R ₁ , 1G ₁ , such as photodiodes corresponding to pixels for one line in which the red filter R, the green filter G, and the blue filter B are sequentially arranged in the light receiving section, 1B ₁ ~ 1R ₂₀₀₀ , 1
It consists of G ₂₀₀₀ and 1B ₂₀₀₀ .

Further, the shift gate 2 transfers the imaging charges obtained by the photoelectric conversion section 1 to the shift register 3.
It is for reading by color, and each shift gate 2
R ₁ , 2G ₁ , 2B _{1 to} 2R ₂₀₀₀ , 2G ₂₀₀₀ , 2B ₂₀₀₀
Consists of.

Each shift gate 2R of this shift gate 2
₁ , 2, 2G ₁ and 2B ₁ are individually connected at their input terminals to the respective light receiving elements 1R ₁ , 1G ₁ and 1B ₁ of the photoelectric conversion unit 1,
Each output terminal is commonly connected to the first transfer stage S ₁ of the shift register 3. Also, each shift gate 2R ₂ , 2G
₂ , 2B ₂ have their respective input ends individually connected to the respective light receiving elements 1R ₂ , 1G ₂ , 1B ₂ of the photoelectric conversion unit 1, and their respective output ends are common to the second transfer stage S ₂ of the shift register 3. It is connected. Similarly, the other shift gates 2R ₃ , 2
G ₃ , 2B _{3 to} 2R ₂₀₀₀ , 2G ₂₀₀₀ , and 2B ₂₀₀₀ are also the light receiving elements 1R ₃ , 1G ₃ , 1B _{3 to} 1R of the photoelectric conversion unit 1.
₂₀₀₀ , 1G ₂₀₀₀ , 1B ₂₀₀₀ and the transfer stages S _{3 to} S ₂₀₀₀ of the shift register 3 are connected. And
Each light receiving element 1R ₁ , 1 for red image pickup of the photoelectric conversion unit 1
Each shift is connected to R ₂ ~1R ₂₀₀₀ gates 2R _1, 2
R _{2 to} 2R ₂₀₀₀ are gate-controlled by the red imaging charge shift pulse φR. In addition, each light receiving element 1 for green image pickup
Each shift gate 2 connected to G ₁ , 1G _{2 to} 1G ₂₀₀₀
G ₁ , 2G _{2 to} 2G ₂₀₀₀ are gate-controlled by the green image pickup charge shift pulse φG. Further, the shift gates 2B ₁ , 2B _{2 to} 2B ₂₀₀₀ connected to the light receiving elements 1B ₁ , 1B _{2 to} 1B ₂₀₀₀ for blue image pickup are gate-controlled by the blue image pickup charge shift pulse φG. This allows
Imaging charges obtained by the photoelectric conversion unit 1 are read out by the color into the shift register 13 via the shift gate 2.

Further, the shift register 3 includes the light receiving elements 1R ₁ , 1G ₁ , 1B _{1 to} 1R of the photoelectric conversion section 1.
Total of ₂₀₀₀ , 1G ₂₀₀₀ , 1B ₂₀₀₀ , that is, 1 / the number of pixels
Of 3 of the number of stages consisting of transfer stages S ₁ ~S _2000. The shift register 3 is driven by a transfer clock φ, transfers the image-capturing charges read from the photoelectric conversion unit 1 via the shift gate 2 in a dot-sequential manner, and outputs from the output unit 3 _OUT via the output buffer 4. Output. The output section 3 _OUT of the shift register 3 is reset by a reset pulse φ _RESET synchronized with the transfer clock φ.

That is, in the solid-state color image pickup device of the first embodiment having such a configuration, as shown in the timing chart of FIG. 2, the light receiving elements 1R ₁ , 1 of the photoelectric conversion section 1 are
The imaging charges of each color obtained by G ₁ , 1B _{1 to} 1R ₂₀₀₀ , 1G ₂₀₀₀ , and 1B ₂₀₀₀ are read out by color into the shift register 3 through the shift gate 2, and the imaging charges of each color are read from the shift register 3. Line-sequential output is performed for each color via the output buffer 4.

By reading out the image-capturing charges of the respective colors through the common shift register 3 as described above, there is no level difference in the image-capturing output signals of the respective colors. Moreover, since the image-capturing charges of the respective colors are read out line-sequentially, color mixing does not occur. Thereby, the black side dynamic range of the captured image can be significantly improved. Moreover, in the solid-state color image pickup device of the first embodiment, the shift register 3 is
Since the number of transfer stages is ⅓ of the number of pixels of the photoelectric conversion unit 1, the structure can be simplified.

The image pickup apparatus according to the present invention is constructed as shown in FIG. 3, for example.

The solid-state color image pickup device of the second embodiment shown in FIG. 3 comprises a photoelectric conversion section 11, a shift gate 12, a shift register 13, an output buffer 14 and a sample hold circuit 15.

The photoelectric conversion unit 11 has a red filter R, a green filter G, and a light receiving unit in the same manner as in the first embodiment.
Light receiving elements 11R ₁ , 11 such as photodiodes corresponding to pixels for one line in which blue filters B are sequentially arranged
G ₁ , 11B _{1 to} 11R ₂₀₀₀ , 11G ₂₀₀₀ , 11B ₂₀₀₀
Consists of.

Further, the shift gate 2 transfers the imaging charges obtained by the photoelectric conversion section 1 to the shift register 1.
3 for reading by color, each shift gate 12
R ₁ , 12G ₁ , 12B _{1 to} 12R ₂₀₀₀ , 12G ₂₀₀₀ ,
It consists of 12B ₂₀₀₀ .

Each shift gate 12 of this shift gate 3
R ₁ , 12G ₁ , 12B _{1 to} 12R ₂₀₀₀ , 12G ₂₀₀₀ ,
12B ₂₀₀₀ is each light receiving element 11R of the photoelectric conversion unit 11
₁ , 11G ₁ , 11B _{1 to} 11R ₂₀₀₀ , 11G ₂₀₀₀ , 1
1B ₂₀₀₀ and the transfer stages S _{1 to} S of the shift register 13
Connected between ₂₀₀₀ and. Then, the respective light receiving elements 11R ₁ and 11R ₂ to ₁ for red image pickup of the photoelectric conversion unit 11
Each shift gate 12R ₁ , 12R connected to 1R _{2000
2 to} 12R ₂₀₀₀ are gate-controlled by the red imaging charge shift pulse φR. In addition, each light receiving element 1 for green image pickup
The respective shift gates 12G ₁ , 12G _{2 to} 12G ₂₀₀₀ connected to 1G ₁ and 11G _{2 to} 11G ₂₀₀₀ are gate-controlled by a green image pickup charge shift pulse φG. Further, each of the light receiving elements 11B ₁ and 11B _{2 to} 11B ₂₀₀₀ for blue imaging is used.
Shift gates 12B ₁ and 12B _{2 to} 12 connected to
B ₂₀₀₀ is gate-controlled by the blue imaging charge shift pulse φG. As a result, the image pickup charges obtained by the photoelectric conversion unit 1 are read out to the shift register 13 by color through the shift gate 2.

Further, the shift register 13 includes the light receiving elements 11R ₁ , 11G ₁ and 11B of the photoelectric conversion section 11.
The transfer stages S _{1 to} S _{6000 have the same} number of stages as the total number of _{1 to} 11R ₂₀₀₀ , 11G ₂₀₀₀ , and 11B ₂₀₀₀ , that is, the number of pixels.
The shift register 3 is driven by a transfer clock φ and transfers the image-capturing charges read from the photoelectric conversion unit 11 via the shift gate 12 in a dot-sequential manner to output the output unit 1.
Output from 3 _OUT through the output buffer 14. The output section 13 _OUT of the shift register 13 is reset by a reset pulse φ _RESET, which is the transfer clock φ decimated to 1/3. As a result, the output 13 _OUT of the shift register 13 outputs 3 times the transfer clock φ.
The clock, that is, the image pickup charges for three pixels are integrated and read. The output unit 13 of the shift register 13 is
The image-capturing charge for one pixel out of the image-capturing charges for three pixels integrated at _OUT is the image-capturing charge of a specific color read through the shift gate 2, but the image-capturing charge for the other two pixels. Has a zero charge amount because the shift gate 2 is closed. Therefore, the shift register 1
From the output section 13 _{OUT of} No. 3, the image pickup charges of a specific color are read out in three clock cycles by integrating the image pickup charges of three clocks of the transfer clock φ, that is, three pixels.

Then, the sample hold circuit 15
From the shift register 13 to the output buffer 14
The image pickup output read out through is sampled and held by the sampling pulse φ _{S / H in} which the transfer clock φ is decimated to ⅓, and is output.

That is, in the solid-state color image pickup device of the second embodiment having such a configuration, as shown in the timing chart of FIG.
R ₁ , 111G ₁ , 11B _{1 to} 11R ₂₀₀₀ , 11
The image-capturing charges of the respective colors obtained by G ₂₀₀₀ and 11B ₂₀₀₀ are read out by the color into the shift register 13 through the shift gate 12, and the image-capturing charges of the respective colors through the output buffer 4 by the shift register 3. It is output line-sequentially.

Therefore, also in the solid-state color image pickup device of the second embodiment, since the image pickup charges of each color are read out through the common shift register 13, there is no level difference in the image pickup output signal of each color. Moreover, since the image-capturing charges of the respective colors are read out line-sequentially, color mixing does not occur.

[0026]

As is apparent from the above description, in the solid-state color image pickup device according to the present invention, since the image pickup charges of each color are read through the common shift register, a level difference occurs in the image pickup output signal of each color. Never. Moreover, since the image-capturing charges of the respective colors are read out line-sequentially, color mixing does not occur. Thereby, the black side dynamic range of the captured image can be significantly improved.

Therefore, according to the present invention, there is provided a solid-state color image pickup device which performs color image pickup, does not cause a level difference due to the characteristics of the shift register in the image pickup output of each color, and does not cause color mixture. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of a solid-state color image pickup device according to the present invention.

FIG. 2 is a timing chart showing the operation of the first embodiment.

FIG. 3 is a diagram showing a configuration of a second embodiment of the solid-state color imaging device according to the present invention.

FIG. 4 is a timing chart showing the operation of the second embodiment.

FIG. 5: First conventional color linear image sensor
It is a figure which shows the structure of.

[FIG. 6] Second conventional color linear image sensor
It is a figure which shows the structure of.

FIG. 7: Third conventional color linear image sensor
It is a figure which shows the structure of.

[Explanation of symbols]

 1, 11 ... Photoelectric conversion unit 2, 12 ... Shift gate 3, 13 ... Shift register

Claims (3)

[Claims] 1. A color filter comprising a light-receiving part and a color filter arranged in sequence.
A line photoelectric conversion unit, a dot-sequential output shift register from which the image pickup charges obtained by the photoelectric conversion unit are read, and a shift gate provided between the photoelectric conversion unit and the shift register and gate-controlled for each color. A solid-state color image pickup device comprising: an image pickup charge obtained by the photoelectric conversion unit, which is read line-sequentially into the shift register for each color through the shift gate. 2. The solid-state color image pickup device according to claim 1, wherein the shift register has a transfer stage number that is ⅓ of a pixel number of the photoelectric conversion unit. 3. The shift register has the same number of transfer stages as the number of pixels of the photoelectric conversion unit, and is supplied with a reset pulse thinned to 1/3 of a transfer clock. Solid-state color imaging device.