JP2002247452A - Solid-state imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state imaging device that attains a multi-pixel configuration without employing an increased drive frequency of a horizontal transfer register so as to be compatible with a high frame rate. SOLUTION: Horizontal transfer registers 120A, 120B are respectively provided to two sides of an image pickup section comprising a light receiving section and vertical transfer registers 110A, 110B. Each of the vertical transfer registers 110A, 110B transfers signal electric charges in an opposite direction at an interval of one column, the vertical transfer register 110A of an odd number column transfers the signal charges in a direction of the arrow (a) in Figure 1 and transmits the signal charges to the one horizontal transfer register 120A. Furthermore, the vertical transfer register 110B of an even number column transfers the signal charges in a direction of the arrow (b) in the Figure 1 and transmits the signal charges to the other horizontal transfer register 120B. Furthermore, each pixel is shifted by a 1/2 pixel pitch in the vertical direction at an interval of one column so as to reduce the interval in the oblique direction without extending the interval between the vertical direction and the horizontal direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device in which signal charges in a light receiving section are transferred in a reverse direction by a plurality of vertical transfer registers and sent to horizontal transfer registers arranged in the respective transfer directions. Related to the element.

[0002]

2. Description of the Related Art Conventionally, for example, in a CCD image pickup device used for a two-dimensional image sensor, a plurality of light receiving sections constituting image pickup pixels are arranged in a matrix.
In general, a plurality of vertical transfer registers are provided along each column of each light receiving section, and a horizontal transfer register is provided at one end of each vertical transfer register. On the other hand, in a CCD image pickup device used for a camera for both a moving image and a still image, a configuration corresponding to an all-pixel reading mode that does not require a mechanical shutter is desired. In this case, it is necessary to cope with an increase in the number of pixels for improving image quality and a high frame rate for moving images.

[0003]

However, in order to achieve both high pixel count and high frame rate in the above-described CCD image sensor for both moving image and still image, it is necessary to increase the driving frequency of the horizontal transfer register. In addition, it is necessary to develop an output circuit having a wide frequency band, which is difficult at present. For example, even when a part of an XGA class image is cut out from a still image and used for a moving image, the horizontal drive frequency exceeds 50 MHz in order to achieve a normal frame rate of 60 frames / sec.

It is an object of the present invention to provide a solid-state imaging device capable of increasing the number of pixels without increasing the driving frequency of a horizontal transfer register and capable of coping with a high frame rate. is there.

[0005]

According to the present invention, in order to achieve the above object, a plurality of light receiving portions arranged substantially in a matrix on a semiconductor substrate, and arranged along each row of the light receiving portions,
A plurality of vertical transfer registers for vertically transferring signal charges accumulated in each light receiving unit, and a horizontal transfer register for horizontally transferring signal charges transferred by the vertical transfer registers; The horizontal transfer register is located at one end along both ends of the vertical transfer register.
The plurality of vertical transfer registers are provided, and the plurality of vertical transfer registers transfer the signal charges in the opposite direction every predetermined column, and send the signal charges to the horizontal transfer registers arranged in the respective transfer directions. I do.

In the solid-state imaging device according to the present invention, the plurality of vertical transfer registers arranged along each column of the light receiving section constituting the imaging pixel transfer the signal charges in the opposite direction every predetermined column, and transfer each signal. The signal charges are transmitted to the horizontal transfer registers arranged in the directions. Therefore, the number of horizontal transfer registers can be increased as compared with the conventional configuration in which a horizontal transfer register is provided only at one end of the vertical transfer register, and the driving frequency of each horizontal transfer register can be increased accordingly. , And can cope with the increase in the number of pixels. Further, by selecting a plurality of horizontal transfer registers and using them as output signals, it is also possible to thin out the imaging pixels in the horizontal direction, and it is possible to easily cope with a high frame rate of moving images. Further, in the present invention, in addition to the above-described configuration, by vertically arranging the columns adjacent to each other in the horizontal direction by a predetermined interval smaller than one pixel pitch in the vertical direction, It is possible to improve the resolution in the oblique direction without lowering the resolution in the horizontal direction.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the solid-state imaging device according to the present invention will be described below. The embodiments described below are preferred specific examples of the present invention, and various technically preferable limitations are added. However, the scope of the present invention is not limited to the embodiments described below. The embodiments are not limited to these embodiments unless otherwise specified.

FIG. 1 is a schematic plan view showing an example of the arrangement of each transfer register of a solid-state imaging device according to an embodiment of the present invention. The solid-state imaging device shown in FIG. 1 has horizontal transfer registers 120A and 120B provided on two sides of an imaging unit formed by a light receiving unit (not shown) and vertical transfer registers 110A and 110B, respectively. That is,
The light receiving units constituting the imaging pixels are arranged in a substantially matrix shape in the imaging unit, and a plurality of vertical transfer registers 110A and 110B are provided along each column of the light receiving units. Then, each vertical transfer register 110A, 110B
Transfer signal charges in the opposite direction every other column. The vertical transfer registers 110A in the odd-numbered columns transfer the signal charges in the direction indicated by the arrow a in FIG. 1, and transfer the signal charges to one horizontal transfer register 120A. Send out charge. The even-numbered vertical transfer registers 110B transfer the signal charges in the direction indicated by the arrow b in FIG. 1, and send the signal charges to the other horizontal transfer register 120B.

In such a solid-state imaging device, the number of horizontal transfer registers can be increased as compared with a conventional configuration in which horizontal transfer registers are provided only at one end of a vertical transfer register. Horizontal transfer register 120
A, 120B can be accommodated without increasing the driving frequency. Also, the horizontal transfer registers 120A and 120A
By selecting 0B and using it as an output signal, it is also possible to thin out the imaging pixels in the horizontal direction, and it is possible to easily cope with a high frame rate of a moving image.

In this embodiment, the horizontal transfer registers 120 are provided on both sides of the vertical transfer registers 110A and 110B.
A and 120B are provided one by one. For example, the horizontal transfer registers 12 are provided on both sides of the vertical transfer registers 110A and 110B.
0A and 120B may be provided two by two, and the signal charge of each light receiving unit may be distributed by each horizontal transfer register. Further, although the transfer direction of the signal charge by each of the vertical transfer registers 110A and 110B is set to the opposite direction every other column, the present invention is not limited to this. For example, the transfer direction may be set to the opposite direction every two columns. In the example shown in FIG. 1, the signal charge of each light receiving unit is divided into two by two horizontal transfer registers. However, by providing two horizontal transfer registers on both sides of the vertical transfer register, the light receiving unit is provided. Signal charge of 4
Transfer can be performed by dividing the data into four by the horizontal transfer register, and it is possible to cope with an increase in the number of pixels.

Next, the pixel arrangement in the solid-state imaging device having such a configuration will be described. 2 is a schematic plan view showing an example of a pixel arrangement of the solid-state imaging device shown in FIG. 1 in comparison with a conventional example. FIG. 2A is a conventional pixel arrangement, and FIG. Is shown. As shown in FIG. 2A, the conventional solid-state imaging device has a structure in which each pixel 10 is arranged on a straight line in a vertical direction and a horizontal direction. In this case, the distance between the pixels 10 is such that the diagonal distance G2 is wider than the vertical and horizontal distance G1. Therefore, in this structure, the resolution in the oblique direction is reduced. Therefore, conventionally, in order to increase the resolution in the oblique direction, the pixel arrangement shown in FIG.
Are arranged diagonally, and the diagonal space is reduced from G2 to G1. However, in this case, on the contrary, the interval between the vertical direction and the horizontal direction increases from G1 to G2, and the resolution in the vertical direction and the horizontal direction decreases.

Therefore, in the solid-state imaging device of this embodiment, FIG.
As shown in (B), by displacing the arrangement of each pixel in the vertical direction every other column, an interval G1 between the vertical direction and the horizontal direction is obtained.
Without increasing the distance G3 in the oblique direction. Specifically, the pixel rows adjacent to each other in the horizontal direction are arranged in a state shifted by a half pixel pitch in the vertical direction. Thereby, the gap G3 in the oblique direction is obtained.
Is larger than the distance G1 and smaller than the distance G2, so that the resolution in the oblique direction can be improved in a well-balanced manner. Note that, in the present invention, the arrangement of each pixel having a certain shift as shown in FIG. In this example, each pixel column is shifted by a half pixel pitch, but the present invention is not limited to this.

FIG. 3 is a partial plan view showing a specific example of the electrode arrangement of the vertical transfer register in the solid-state imaging device having the above-described configuration. As shown in the figure, the solid-state imaging device of the present example has a first electrode 140A, a second electrode 140B, and a third electrode 1A.
It is driven by a 40C three-phase electrode. That is, each of the electrodes 140A, 140B, and 140C includes a lower first electrode (shown by a solid line in FIG. 3) disposed on a semiconductor substrate via an insulating film, and a second electrode (an alternate long and short dashed line in FIG. 3) formed thereon. 140B is disposed via an insulating film (not shown), and a third electrode (shown by a two-dot broken line in FIG. 3) 140C is disposed thereover via an insulating film. Further, a light-shielding film (not shown) is provided above the electrodes 140A, 140B, and 140C with an insulating film interposed therebetween, and shields a region other than the light-receiving unit from light. Then, the light receiving section of each pixel receives light from an opening formed in the light shielding film and performs photoelectric conversion.

In FIG. 1, each electrode 140A, 140
A region 150 where B and 140C are not arranged is a region substantially corresponding to the opening. In such an electrode arrangement, the operation of the electrodes 140A, 140B, and 140C causes the signal charges in the vertical transfer registers 110A of the odd-numbered columns in the order of "A1,""A2,""A3," and "A4" in FIG. And the signal charge is transferred in the direction indicated by the arrow a in FIG.

On the other hand, the vertical transfer registers 110B of even columns
In FIG. 3, "B1,""B2,""B3," and "B4"
, And the signal charges are transferred in the direction indicated by the arrow b in FIG. Thus, the reverse transfer of the vertical transfer registers 110A and 110B every other column is realized,
The signal charges are transferred to the horizontal transfer registers 120A and 120B on both sides described above. In this example, an example of three-phase driving has been described, but the present invention is not limited to this, and another driving method can be adopted.

In the solid-state image pickup device having the above-described configuration, for example, in a CCD image pickup device capable of reading all pixels independently, which can be used for both moving images and still images, it is possible to perform vertical reverse transfer of adjacent pixel rows. It is possible to cope with an increase in the number of pixels without increasing the driving frequency of the horizontal transfer register. Also, by simultaneously shifting the positions of adjacent pixel columns in the vertical direction within a unit pixel size or less, it is possible to improve the resolution in the oblique direction. The present invention is not limited to the above-described CCD image pickup device that can be used for both moving images and still images and is compatible with all-pixel independent reading, and can be widely applied to various other solid-state image pickup devices.

[0017]

As described above, according to the present invention, a plurality of vertical transfer registers arranged along each column of the light receiving sections constituting the imaging pixels transfer signal charges in the opposite direction every predetermined column. The signal charge is sent to the horizontal transfer register arranged in the transfer direction of (1). Therefore,
Compared with the conventional configuration in which the horizontal transfer registers are provided only at one end of the vertical transfer registers, the number of horizontal transfer registers can be increased, and the number of horizontal transfer registers can be increased without increasing the driving frequency of each horizontal transfer register. There is an effect that can respond to pixelation. In addition, by selecting a plurality of horizontal transfer registers and using them as output signals, it is also possible to thin out the imaging pixels in the horizontal direction, so that it is possible to easily cope with a high frame rate of a moving image.

Further, in the present invention, the rows adjacent to the plurality of light receiving sections in the horizontal direction are arranged in the vertical direction so as to be shifted by a predetermined interval smaller than one pixel pitch. Therefore, the resolution in the oblique direction can be improved without lowering the resolution in the vertical and horizontal directions, and there is an effect that a high-resolution solid-state imaging device can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing an example of the arrangement of each transfer register of a solid-state imaging device according to an embodiment of the present invention.

2 is a schematic plan view showing a pixel arrangement example of the solid-state imaging device shown in FIG. 1 in comparison with a conventional example.

FIG. 3 is a partial plan view showing a specific example of an electrode arrangement of a vertical transfer register in the solid-state imaging device shown in FIG.

[Explanation of symbols]

10 pixels, 110A, 110B, vertical transfer registers, 120A, 120B, horizontal transfer registers, 140
A, 140B, 140C ... vertical transfer electrodes, 150 ...
Opening area.

Claims (7)

[Claims] 1. A plurality of light receiving units arranged in a substantially matrix on a semiconductor substrate, and a plurality of light receiving units arranged along respective columns of the light receiving units and transferring signal charges accumulated in the respective light receiving units in a vertical direction. In a solid-state imaging device having a vertical transfer register and a horizontal transfer register that transfers signal charges transferred by the vertical transfer register in a horizontal direction, one horizontal transfer register is provided along both ends of the vertical transfer register. Alternatively, a plurality of the vertical transfer registers are provided, and the plurality of vertical transfer registers transfer the signal charges in the opposite direction every predetermined column, and send the signal charges to the horizontal transfer registers arranged in the respective transfer directions. Solid-state imaging device. 2. The method according to claim 1, wherein one or more horizontal transfer registers provided along both ends of the vertical transfer register transfer the signal charges transferred from each vertical transfer register in one direction. The solid-state imaging device according to claim 1. 3. The solid-state imaging device according to claim 1, wherein the horizontal transfer register is selected to output a signal charge in accordance with an imaging signal output mode. 4. The solid-state imaging device according to claim 3, wherein when the output mode of the imaging signal is the all-pixel reading mode, signal charges are output using all horizontal transfer registers. 5. The solid-state imaging device according to claim 3, wherein when the output mode of the imaging signal is a moving image mode, a part of the horizontal transfer registers is selected to output signal charges. 6. The light receiving unit according to claim 1, wherein the plurality of light receiving units are arranged in such a manner that rows adjacent in the horizontal direction are vertically shifted by a predetermined interval smaller than one pixel pitch. Solid-state imaging device. 7. The solid-state imaging device according to claim 4, wherein the predetermined interval is substantially a half pixel pitch.