JPH0685584B2 - Solid-state image sensor for color - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a CCD solid-state image pickup device and a color solid-state image pickup device including a micro color filter arranged corresponding to pixels thereon, and particularly to a horizontal resolution. Has been improved
The present invention relates to a solid-state image sensor suitable for NTSC movie.

[Prior art]

Frame transfer type CC (hereinafter referred to as FT type) CC
In D, the photoelectric conversion element itself has a charge transfer function,
Although the structure is simple and the number of pixels is increased, especially the number of pixels in the horizontal direction can be sufficiently taken, on the other hand, it has the following drawbacks. That is, since the transparent electrode made of polysilicon for transferring charges is arranged on the surface of the photoelectric conversion element, absorption of light occurs here and the sensitivity is lowered. In particular, when the FT type CCD is used for color, light having a short wavelength, that is, color B is significantly absorbed. In this case, since it is necessary to balance the colors of the colors R, G, and B, the sensitivity of the photoelectric conversion elements of the colors R and G must be reduced in accordance with the photoelectric conversion elements of the color B, and the overall sensitivity is reduced. ing.

An interline CCD (hereinafter referred to as IT method) CCD was developed to improve the drawbacks of the FT method.
Has a charge transfer section that is independent of the photoelectric conversion element rows and arranged alternately along the vertical photoelectric conversion elements, so that the horizontal resolution is relatively lower than that of the FT method under the same design rule. In other words, in order to obtain a horizontal resolution equivalent to that of the FT method, it was necessary to use a thinner design rule, which was extremely disadvantageous in manufacturing.

The present inventor has already been as sensitive as an IT CCD and has an FT
We proposed a solid-state imaging device (Japanese Patent Application No. 61-89505, filing date: April 18, 1986) that can obtain horizontal resolution similar to that of the CCD.

As shown in FIG. 2, this solid-state imaging device has a light receiving unit 1 provided by the IT method, a charge storage unit 2 provided by the FT method, and a horizontal shift register 3 as main components, The charge transfer portion 2a forming the portion 2 is also used as the photosensitive area. Therefore, the charge transfer unit 2a has both a photoelectric conversion function and a charge transfer function, and as a result, this solid-state imaging device has a horizontal resolution similar to that of a FT CCD.

[Problems to be solved by the invention]

However, such a solid-state imaging device needs to be configured so that the light receiving unit is not exposed while the charge transfer unit functions as a charge transfer function, and therefore its application is, for example, when the exposure period is Limited to still cameras that can be constrained by shutters.

The object of the present invention is to obtain sensitivity as high as that of an IT type CCD, and to obtain double the horizontal resolution based on the same design rule as the conventional element,
Another object of the present invention is to provide a solid-state color image pickup device that can also be used for movies.

[Means for solving problems]

In order to achieve the above object, the solid-state image sensor according to the present invention is configured as follows. That is, the color arrangement of the micro color filter is the first of the three primary colors or the complementary colors in the vertical direction.
Row of colors, and a second of the three primary or complementary colors in the vertical direction
And two columns of the third color and the third color are alternately arranged in the horizontal direction. Further, the pixel corresponding to the first color of the solid-state image pickup device is composed of an FT type photoelectric conversion element, and accordingly, one charge storage unit and one charge storage unit are provided for the first color.
Two horizontal CCDs are provided. On the other hand, the pixels corresponding to the second color and the third color are composed of IT type photoelectric conversion elements, and accordingly, are arranged between the pixels of the second color and the third color and the pixel of the first color, respectively. A transfer gate is provided and a second
Other charge storage portions and other horizontal CCDs are provided for the color and the third color. The output of the pixel at the output side end of the pixel of the first color, that is, the pixel of the second color and the pixel of the third color coupled through the transfer gate is the total of the two charge storage units. It is accumulated alternatively in one side.

[Action]

The CCD solid-state image sensor according to the present invention operates in the FT method for the first color, for example, the color G, and in the IT method for the second and third colors, for example, the color R and the color B. Therefore, it can be called a FT-IT hybrid CCD. The signal charge formed in the photoelectric conversion element for color G is transferred to the storage section for color G during the signal transfer cycle. Color R during this period
And the signal charge of the color B remains in the photoelectric conversion element.
When all the signal charges of the color G are transferred to the storage unit, next,
The color R and color B signal charges are transferred to the color G via the transfer gate.
To all photoelectric conversion elements. That is, the photoelectric conversion element of color G thereafter operates as a vertical charge transfer unit.
The color R and color B signal charges transferred into the color G photoelectric conversion element are transferred to the color R or color B storage unit during the signal transfer cycle. As soon as all the color R and color B signal charges have been transferred to the color R or color B storage unit, these signal charges, along with the color G signal charges already prepared in the color G storage unit, are stored in respective horizontal directions. Charge transfer section or horizontal CC
Read simultaneously via D.

While the photoelectric conversion element of color G is operating as a vertical charge transfer section, the vertical charge transfer section also generates a signal charge of color G as a photoelectric conversion element. However, since the vertical transfer of the signal charge to the storage unit is performed at a very high speed, the color G
The effect of color mixing with is negligible. Therefore,
Unlike the conventional element, it is not necessary to shield the light receiving portion from light, and therefore, it can be used for movies.

As described above, in the color solid-state image sensor according to the present invention,
For example, the color G is operated by the FT system, and the colors R and B are operated by the IT system. At this time, based on the IT system, a photoelectric conversion element for color G is used as a vertical transfer unit, and two storage units for the color G and the color R or the color B are respectively provided at the output side terminals of the vertical transfer unit to output the output signal. Is stored in either one.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

One embodiment shown in FIG. 1 is a schematic diagram showing the configuration of a solid-state image sensor according to the present invention. The light receiving unit 10 has photoelectric conversion elements arranged in a matrix, and a micro color filter is arranged on the light receiving unit 10. The micro color filter has three colors R, G and B corresponding to the respective photoelectric conversion elements. In the micro color filter having the configuration according to the present invention, a column in which the same color, that is, the color G is arranged in the vertical direction and two colors R and B are alternately arranged in the vertical direction, and the same color is arranged in the row direction. Columns arranged like this,
Consist of so-called G stripe R / G line sequential arrangements which are alternately arranged in the horizontal direction. This arrangement is shown schematically by the symbols R, G, B in the figure.

Since the photoelectric conversion element arranged under the filter G also plays the role of a charge transfer element itself, the surface of these photoelectric conversion elements is provided with a four-phase driven polysilicon transparent electrode 11 for transfer control. Has been. On the other hand, the surface of the photoelectric conversion element below the filters R and B is opened and a polysilicon electrode is not provided. Instead, a transfer gate 12 is provided for each element between the photoelectric conversion element for colors R and B and the photoelectric conversion element for color G. Therefore, in this embodiment, the photoelectric conversion element for the color G is the photoelectric conversion of the color G, the color G
It performs the three functions of electrode transfer of R and charge transfer of color R or B. In the figure, a portion surrounded by a dotted line is a channel stopper formed on a silicon substrate, and a photoelectric conversion element and a charge transfer element, that is, a self-scanning CCD shift register is formed in a portion surrounded by the channel stopper. There is.

Two charge accumulating portions 13 and 14 are provided below the light receiving portion 10 in the figure. The first storage unit 13 is arranged adjacent to the light receiving unit 10,
It has a first horizontal CCD 15 at its output.

The second storage unit 14 is adjacent to the first storage unit 13,
Further, it is arranged at a position sandwiching the first horizontal CCD 15, and the output end thereof is also provided with the second horizontal CCD 16.

Although not shown in the figure, transfer gates are provided between the first storage unit 13 and the first horizontal CCD 15 and between the first horizontal CCD 15 and the second storage unit 14, respectively. It controls the charge transfer destination.

The signal charge generated by the photoelectric conversion element of color G is sent to the first storage unit 13 via the photoelectric conversion element itself. Immediately after this transfer process is completed, the signal charges generated in the photoelectric conversion elements for the colors R and B are simultaneously transferred to the emptied photoelectric conversion elements for the color G through the transfer gate 12.

Next, the signal charges of the color G already accumulated in the first accumulation unit 13 are transferred to the second accumulation unit 14, and the signal charges of the colors R and B transferred to the photoelectric conversion element for the color G are converted to the first charges. Each is transferred to the storage unit 13 and the read preparation is completed. The transfer control of the signal charges is not limited to the above-described pattern, and for example, the transfer of the signal charges of the colors R and B is started only after the signal charges of the color G are transferred to the second storage section. You can also

The signal charges of the colors R and B accumulated in the first accumulator and the signal charges of the color G accumulated in the second accumulator in the state where the signal charge read-out preparation is completed are sequentially applied to the horizontal CC of the color.
Transferred to D15,16. The signal charge is read out from the horizontal CCDs 15 and 16 in a conventional manner, and the signal charge is taken out as an NTSC field signal via buffer amplifiers 17 and 18, respectively. The signal charges of colors R and B are separated by a switching circuit (not shown) provided at the subsequent stage of the buffer amplifier 17.

In the above embodiment, the case where the color filter is composed of three primary colors has been described, but it can be easily inferred that the color filter may be a complementary color. Further, it is obvious that the solid-state image sensor of the present invention works well even when applied to a still camera.

〔The invention's effect〕

The solid-state imaging device according to the present invention has two charge storage portions, and is arranged so that all the signal charges generated in the light receiving portion are distributed to the respective storage portions and then read out by each horizontal CCD. It is not necessary to shield the part from light and can be used for movies. In addition, the light receiving part is a CCD of FT-IT hybrid system.
As a light receiving area by arranging a filter in the vertical transfer section of the IT system as a light receiving area.
It has double the horizontal resolution. Moreover, since the light receiving element for color B does not have a transparent electrode, the defect of the FT method is eliminated and the conventional
It has the same sensitivity as the IT system. Therefore, since color balance is achieved, there is no need to reduce the sensitivity of other colors, and extremely high sensitivity can be obtained as a whole.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining the configuration and operation of a solid-state image pickup device for color according to the present invention, and FIG. 2 is a schematic diagram for explaining the solid-state image pickup device already proposed by the present inventor. 10 ... Light receiving part, 11 ... Polysilicon transparent electrode, 12 ... Transfer gate, 13,14 ... Charge storage part, 15 ... First horizontal CCD, 16 ... Second horizontal CCD, 17,18 ... Buffer amplifier

Claims (1)

[Claims] 1. A color solid-state image pickup device comprising a CCD type solid-state image pickup device and a microcolor filter arranged corresponding to pixels on the CCD solid-state image pickup device, wherein the color array of the microcolor filters has three primary colors or complementary colors in the vertical direction. A column in which the first color is arranged and a column in which two second colors and three third colors of three primary colors or complementary colors are alternately arranged in the vertical direction are alternately arranged in the horizontal direction, and are solid. Pixels corresponding to the first color of the image pickup element are composed of a frame transfer type photoelectric conversion element, while pixels corresponding to the second and third colors are formed of an interline type photoelectric conversion element. A transfer gate is provided between the pixel of the third color and the pixel of the first color, and a first charge storage section and a first horizontal CCD are provided for the second and third colors. And the second color for the first color A charge storage section and a second horizontal CCD are provided, and the signal charge of the pixel corresponding to the first color is stored in the second charge storage section via the first charge storage section, The signal charge of the pixel corresponding to the second or third color is stored in the first charge storage unit, and
Solid-state image pickup device for color, wherein the signal charges of the above colors and the signal charges of the second and third colors are simultaneously read.