JPH0659102B2 - Solid-state image sensor for color image - Google Patents

Description

The present invention relates to an image sensor including a photoelectric conversion unit, a charge transfer unit, and a transfer control unit, and a scanning line direction corresponding to each pixel on the image sensor. A microfilter in which rows of a single color are arranged is provided. In this case, rows of pixels corresponding to one scanning line are alternately assigned to the A field and the B field due to interlacing, and also correspond to one scanning line. A pixel is composed of two rows, and two rows (for example, R, G, and B) have two colors (for example, B and G) in two rows corresponding to odd-numbered scan lines of respective fields.
And the remaining color (R) and one of the two colors (for example, G) are assigned to the two rows corresponding to the even-numbered scan lines, and two scan lines are provided for each field. The present invention relates to a solid-state image pickup device for color images, which reproduces three colors.

Originally, the solid-state image sensor is a semiconductor image sensor, but here, the image sensor represents only the semiconductor component of the solid-state image sensor, and the term solid-state image sensor is used for color images in which a microfilter is arranged on the image sensor. Shall be represented.

(Prior Art) A solid-state image pickup device for a color image is configured by disposing, for example, R, G, and B color selection filters corresponding to pixels on an image sensor. But then, at least three pixels are required to form all the colors. Actually, in the interlace method, pixels on adjacent scan lines of different fields can be redundantly used to reduce the apparent deterioration of image quality, but even in this case, a resolution similar to that of a monochrome image can be obtained. Do not mean.

According to recent semiconductor technology, it is possible to increase the density of pixels, and the number of pixel rows reaches twice the number of effective rasters of a normal TV.
For example, an image sensor having vertical 976 pixel rows can be manufactured. If a microfilter having different colors corresponding to pixels is arranged on such an image sensor, four pixels can be used to reproduce all colors,
The same resolution as that for a conventional monochrome image having the number of pixels can be obtained.

In this case, two rows of pixels are used per scanning line.

(Problems to be solved by the invention) However, since each element of the microfilter must be equal in size to the pixel, and the microfilter having a fine structure and the image sensor must be accurately overlapped, It is extremely difficult to assemble a solid-state image sensor for various color images.

The elements of the microfilter are arranged so that the same colors are arranged in the scanning direction, the color of the first row is, for example, B, the color of the second row is G,
The third row is B, the fourth row is G, the fifth row is R, the sixth row is G, the seventh row is R, the eighth row is G, and so on. Repeated placement has already been proposed.

This method is premised on the interlaced method, in which the first, second, fifth and sixth rows form an A field image, and the third, fourth, seventh and eighth rows form a B field.

Since two rows of pixels are used per scanning line as described above, if two independent horizontal transfer CCDs are provided, the image signal of color G is always read from one horizontal CCD and the other horizontal CCD is read. From, the image signals of colors R and B are read alternately for each scanning line. That is, if the color signals R and B from the other horizontal CCD are distributed, the signals of the three colors R, G and B can be read out independently.

In such a solid-state image pickup device for color images, the overlay accuracy of the image sensor and the microfilter is greatly relaxed only in the horizontal direction. Although it can be evaluated in that respect, there are still severe requirements for vertical overlay accuracy.

An object of the present invention is to provide a solid-state image pickup device for a high-resolution color having a fine structure as described at the beginning, which greatly relaxes the requirements concerning the manufacturing precision of the microfilter and the overlay precision of the microfilter on the image sensor. It is in.

(Means and Actions for Solving Problems) According to the present invention, this object is achieved as follows.
That is, in the A field scan line and the B field scan line, the order of the two colors in the vertical direction is reversed,
Therefore, in the microfilter, the colors are arranged such that the color of the row below one field is the same as the color of the row above the other field, and 2 lines per scan line.
In order to transfer the signals of the pixels in the row, two horizontal charge transfer sections are provided, and a switching switch is provided after the two horizontal charge transfer sections, and the switching switches are switched for each field. The color signals whose order has been reversed are returned to the normal order every time.

As an example, the row of colors of the micro filter is G from the top,
B, B, G, G, R, R, G ... and so on are repeated in the same order. As mentioned above, the first, second, fifth, sixth, ...
If the pixels in the row are for the A field, the image signal of color G is read from one horizontal CCD at the time of A field scanning, and the color R and the color R are alternately read from each other from the other horizontal CCD. The B image signal is read. Similarly, the third,
If the pixels of rows 4, 7, 8 ... Are for the B field, the image signals of colors R and B are alternately read from one horizontal CCD for each scanning line during the B field scanning. An image signal of color G is read from the other horizontal CCD.

That is, the two horizontal CCDs interchange their roles between the A field and the B field. Therefore, the outputs of the two horizontal CCDs are switched for each field via the switching switch.

As is clear from the above, in the solid-state image pickup device for color images according to the present invention, in the microfilter, one color is always arranged over two continuous rows, which simplifies the manufacture of the microfilter itself. Not only that, but also the requirements concerning the overlay accuracy of the microfilters on the image sensor have been greatly relaxed.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

A microfilter 1 is shown in FIG. The R, G, and B symbols entered here represent the selected color of each element of the filter. Only eight rows are shown in the figure, but further above or below this range are further filters in the same order of color arrangement.

Although it is not clear from the figure, the photoelectric conversion part and the vertical charge transfer part of the image sensor are arranged under the microfilter 1, and in this case, each element of the photoelectric conversion part is R, G,
There is a one-to-one correspondence with the color classification of filter 1 shown by B.

Once during one scanning line period (here, approximately 63.5 μsec),
The charge signals of the pixels in the two rows are read into the horizontal CCDs 2 and 3, respectively. Then, during this period, these signal charges are sent out in parallel from the respective horizontal CCDs 2 and 3. Signals A and B shown on the left side of the microfilter 1 in FIG. 1 represent fields. For example, during the A field, as is apparent from the color arrangement in the figure, the R signal and the B signal are alternately read into the horizontal CCD 2 for each scanning line. On the other hand, the horizontal CCD 3 reads the G signal. In this embodiment, the signals from the respective horizontal CCDs 2 and 3 are transmitted via floating diffusion amplifiers (FDA) 4 and 5.

During the B field, the G signal is read into the horizontal CCD 2 and the horizontal CC is read, as is apparent from the figure.
The R signal and the B signal are alternately read into D3 for each scanning line.

FDA4 reading signals from each horizontal CCD2,3
After 5 and 5, a switching switch 6 is connected. Since the switching switch 6 is switched for each field, the G signal is always output from the output terminal 7, and the R signal and the B signal are always output alternately from the output terminal 8 for each scanning line. Although not shown in the figure, another switching switch is connected after the output terminal 8. Since the switching switch (not shown) is switched for each scanning line, the R signal and the B signal can be taken out independently, that is, the R signal,
The B and G signals can all be taken out independently.

In the illustrated embodiment, the colors are shown as R, G, B, but
In addition to these three colors, the combination of W, C _y and Y _e , W,
It is obvious that a combination of R and B or a combination of G, C _y and Y _e may be used. In short, any combination of colors may be adopted as long as all the colors can be reproduced by operations such as addition and subtraction of color signals and inversion to complementary colors.

FIG. 2 shows in detail the configuration of the switching switch 6 and its peripheral circuits. Horizontal CCD2 via FDA4 and 5
The signals read from 3 and 3 are supplied to buffer amplifiers 9 and 10 consisting of two-stage source followers. The outputs of the buffer amplifiers 9 and 10 are supplied to the switching switch 6.
In this embodiment, the switching switch 6 is composed of four MOS switches 61, 62, 63, 6 each having a control signal applied to its gate.
It consists of four. The MOS switches 62 and 63 are controlled to be on during the A field, and the MOS switches 61 and 64 are controlled to be on during the B field. Therefore, the output of the horizontal CCD 2 is output from the output terminal 8 and the output of the horizontal CCD 3 is output from the output terminal 7 during the A field, while the output of the horizontal CCD 2 is output from the output terminal 7 during the B field. The output of the CCD 3 is output from each output terminal 8. Subsequent processing of these output signals is as described in connection with FIG.

(Effects of the Invention) As described above, according to the solid-state image sensor for color images of the present invention, the color arrangement in the horizontal direction of the microfilter is
By making the same color corresponding to the pixel rows adjacent to each other between the two fields, it was possible to easily manufacture the microfilter itself as a two-pixel pitch. In addition, the overlay accuracy of the microfilters on the image sensor is relaxed.

[Brief description of drawings]

FIG. 1 shows a solid-state image sensor for color images according to the present invention.
FIG. 2 is a schematic block diagram showing an embodiment, and FIG. 2 is a circuit diagram showing an embodiment of the switching switch. 1 ... Micro filter, 2, 3 ... Horizontal charge transfer unit (horizontal CCD), 4, 5 ... FDA, 6 ... Switching switch, 7, 8 ... Output terminal, 9, 10 ... Buffer amplifier

Claims (1)

[Claims] 1. An image sensor comprising a photoelectric conversion unit, a charge transfer unit, and a transfer control unit, and a microfilter in which rows of a single color are arranged in the scanning line direction corresponding to each pixel on the image sensor. At that time, the rows of pixels corresponding to one scanning line are alternately assigned to the A field and the B field due to interlacing, and the pixels corresponding to one scanning line are composed of two rows, and each pixel has an odd number of fields. Two of the three colors (eg R, G, B) in the two rows corresponding to the second scan line (eg B and G)
And the remaining color (R) and one of the two colors (for example, G) are assigned to the two rows corresponding to the even-numbered scan lines, and two scan lines are provided for each field. In a solid-state image sensor for color images, which reproduces three colors from the above, in the A field scanning line and the B field scanning line, the order of the two colors in the vertical direction is reversed. In the filter, each color is arranged so that the color of the row below one field is the same as the color of the row above the other field, and in order to transfer the signals of the pixels of two rows per scanning line. Two horizontal charge transfer units are provided, and a switching switch is provided after the two horizontal charge transfer units. The switching switch is switched for each field, and the order is reversed for each field. Belief Characterized in that the return to the normal sequence, a color image for a solid-state imaging device.