JP2003244545A - Solid-state image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suitable structure for improving light receiving characteristics of rectangular pixels in a solid-state image pickup device, such as the pixels aspect ratio being about '2:1'. <P>SOLUTION: The solid-state image pickup device individually has a rectangular light-receiving region of the pixel aspect ratio which is about '2:1', and provides plural pixels arranged in 2 dimension being offset in 1/2 pixel pitch in the long side direction of the light-receiving region with respect to the short side direction of the light-receiving region, a scanner device which is installed on a light-receiving plane of the plural pixels, scans signal charge and reads out, and an optical instrument which shades light inputted to the light-receiving plane as the pixel pitch in the short-side direction. The plural pixels are separated in each pixel group arranged in a direction of the light-receiving plane and the signal charge are transferred in the order in a direction of the light-receiving plane, a scanning measure drives the plural pixels for each pixel group arranged orthogonally with respect to the direction of the light-receiving plane, and scans the signal charge in a frame transfer system. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device in which a plurality of pixels each having a light receiving region for generating a signal charge according to light incident on a light receiving surface are two-dimensionally arranged.

[0002]

2. Description of the Related Art Conventionally, solid-state image pickup devices having a plurality of pixels arranged two-dimensionally have been used for various purposes. In such a solid-state image pickup device, in order to reduce aliasing caused by aliasing of the Nyquist frequency and false colors that are noticeable in the case of an image pickup device having a plurality of color filters, an OLPF (Optica) that removes a predetermined spatial frequency component is used.
l Low Pass Filter: Some have an optical low pass filter.

Further, as a solid-state image pickup device having a rectangular pixel, Japanese Patent Application Laid-Open No. 2004-187242 is known.

[Patent Document 1] Japanese Patent Laid-Open No. 2000-23171

[0004]

However, the conventional solid-state image pickup device provided with the OLPF has a problem that the sharpness is remarkably lowered as compared with the solid-state image pickup device not provided with the OLPF.

Further, in a solid-state image pickup device used in a device involving image processing such as an electronic camera, a plurality of pixels are arranged two-dimensionally, and in order to uniformly blur incident light in a plurality of directions, a plurality of pixels are arranged. It is necessary to provide a sheet of OLPF. For example, to realize a square aperture by uniformly blurring the incident light in the vertical direction and the horizontal direction, an OLPF that blurs the incident light in the vertical direction and an OLPF that blurs the incident light in the horizontal direction.
And are required.

Therefore, in the conventional solid-state image pickup device, by providing a plurality of OLPFs, the cost is increased, the number of interfaces in the optical path is increased, and flare is increased.
There have been problems such that the thickness of the entire LPF is increased, the aberration characteristics of the optical system are deteriorated, and the space is increased.

Therefore, in the present invention, reduction of false color and prevention of deterioration of sharpness can be carried out in a well-balanced manner, and the number of optical members for blurring incident light (including multiplexing) should be minimized. It is an object of the present invention to provide a solid-state imaging device capable of performing

Another object of the present invention is to provide each of the above solid-state image pickup devices (specifically, a solid-state image pickup device having pixels having an extremely rectangular shape with a pixel aspect ratio of about "2: 1"). It is an object of the present invention to provide a technique for improving the light receiving characteristic of a pixel.

[0009]

A solid-state image pickup device according to claim 1 has a rectangular light-receiving region for individually generating a signal charge according to light incident on a light-receiving surface, and a short side of the light-receiving region. 1 / the pixel pitch in the long side direction of the light receiving region
A plurality of pixels which are offset by two and are arranged two-dimensionally, a scanning means which scans the signal charges to be read out to the outside, and a plurality of pixels which are provided on the light-receiving surface side of the pixels and which shorten the light incident on the light-receiving surface. And an optical member for blurring the pixel pitch in the side direction. These light receiving regions are rectangles whose aspect ratio is approximated to "2: 1". Further, the plurality of pixels are separated for each pixel group arranged in one direction of the light receiving surface, the signal charges are sequentially transferred in one direction of the light receiving surface, and the scanning unit transfers the plurality of pixels to one of the light receiving surface. It is characterized in that each pixel group arranged in a direction orthogonal to one direction is driven and the signal charges are scanned by a frame transfer method.

According to another aspect of the solid-state image pickup device of the present invention, each of the solid-state image pickup devices individually has a rectangular light-receiving region for generating a signal charge according to the light incident on the light-receiving surface, and the rectangular light-receiving region is arranged in the short side direction of the light-receiving region. A plurality of pixels that are two-dimensionally arranged by being offset by ½ of the pixel pitch in the direction of the long side of the light receiving region, a scanning unit that scans the signal charges and reads the signals to the outside, and a scanning unit that is provided on the light receiving surface side of the plurality of pixels. The aspect ratio of the light receiving area is set to "2: 1" by arranging two optical members for blurring the light incident on the light receiving surface in the short side direction by the pixel pitch and two in the long side direction for each light receiving area. It is characterized in that it is provided with a similar microlens and an accumulating portion for accumulating signal charges generated by the light incident on the two microlenses in the light-receiving area, collectively for each light-receiving area.

A solid-state image pickup device according to a third aspect of the present invention is the solid-state image pickup device according to the second aspect, further comprising a light-shielding portion that shields a boundary region between two microlenses arranged in the light-receiving region. To do.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. However, in the following,
As an example of the solid-state imaging device of the present invention, a frame transfer type monochrome solid-state imaging device will be described.

<< Description of First Embodiment >> FIG. 1 is a diagram showing a schematic configuration of a solid-state imaging device corresponding to the first embodiment. In FIG. 1, a solid-state imaging device 1 includes a housing 12 whose opening is closed by a glass substrate 11 and a glass substrate 1.
And the light receiving surface is the glass substrate 1
1 and an image pickup chip 14 provided inside the housing 12 so as to face it.

Further, in FIG. 1, a plurality of pixels 141 are two-dimensionally arranged on the image pickup chip 14. Each pixel 141 is a rectangle whose length ratio in the long side direction and the length in the short side direction is approximated to “2: 1”, and is 1/1 of the pixel pitch in the long side direction with respect to the short side direction. They are offset by two and are arranged in a zigzag manner, and are arranged substantially in a straight line in the long side direction.

The OLPF 13 blurs the incident light with respect to the short side direction of the pixel 141 by the pixel pitch in the short side direction. As a result, the equivalent aperture of each pixel 141 expands in the short side direction of the pixel 141 to form a square shape as shown in FIG. 2, and the pixels 141 adjacent in the short side direction overlap each other. . However, in FIG. 2, the apertures of the pixels 141 arranged in odd-numbered positions are indicated by solid lines and the apertures of the pixels 141 arranged in even-numbered positions are indicated by dotted lines with the short-side direction as a reference.

The sampling points for each pixel 141 are as shown in FIG. By the way, when the solid-state imaging device 1 is a frame transfer type solid-state imaging device, each pixel 1
Most of 41 is occupied by a light receiving region (a region for generating signal charges according to incident light).

FIG. 4 is a diagram showing the structure of the light receiving region in the first embodiment. In FIG. 4, each light receiving region 142 (enclosed by a dotted line) corresponds to the pixel 1 shown in FIG.
Similar to 41, a rectangle in which the length ratio between the long side direction and the short side direction is approximated to “2: 1” (strictly, the length in the short side direction is from the center of a channel stop to the center of an adjacent channel stop). Of the pixel pitch in the short side direction, offset by ½ of the pixel pitch in the long side direction, and arranged in zigzag, and arranged in a straight line in the long side direction. .

Further, in FIG. 4, a channel stop 143 is provided for each column (pixel group) of the light receiving regions 142 arranged in the vertical transfer direction of the light receiving surface (corresponding to the long side direction of the light receiving region).
And a two-phase transparent electrode 144 is provided for each light receiving region 142 (pixel group) arranged in a zigzag pattern along the horizontal transfer direction of the light receiving surface (corresponding to the short side direction of the light receiving region). To such a transparent electrode 144, pulse signals φ1A and φ2A for transferring signal charges are supplied.

According to the structure shown in FIG. 4, the plurality of light receiving regions 142 are separated by the channel stop 143 for each column arranged in the vertical transfer direction of the light receiving surface, and the common transparent electrode 144 is provided. The signal charges generated at 142 can be simultaneously transferred in the vertical transfer direction of the light receiving surface. Therefore, similarly to the existing frame transfer type solid-state imaging device, it is possible to scan the signal charges by the frame transfer method via the storage unit and the horizontal reading unit (not shown).

As described above, in the first embodiment, the single OLPF 13 that blurs the incident light by the pixel pitch in the short side direction with respect to the short side direction of the light receiving region 142 (substantially coincident with the pixel 141) is provided. By itself, an equivalent aperture as shown in FIG. 2 is obtained. Therefore, it is possible to reduce the false color due to the aliasing of the Nyquist frequency while suppressing the decrease in the sharpness to a minimum, and to provide the conventional problem that occurs by providing a plurality of optical members that blur the incident light (cost increase, It is possible to avoid an increase in flare, deterioration of aberration characteristics of the optical system, an increase in space, etc.).

Further, in the first embodiment, the transparent electrode 14
By making the shape of 4 into a zigzag shape as shown in FIG. 4,
The pixel arrangement of FIG. 1 (1/2 offset in alternate columns) is realized.

In the first embodiment, as shown in FIG. 4, the light receiving regions 142 (first embodiment) are arranged so that the long side direction of each light receiving region 142 coincides with the vertical transfer direction of the light receiving surface. However, the light receiving region 142 may be arranged so that the long side direction coincides with the horizontal transfer direction of the light receiving surface as shown in FIG.

However, when the light receiving area 142 is arranged as shown in FIG. 5, in order to realize the scanning of the signal charges by the frame transfer method, the channel stop 143 is provided in the vertical transfer direction of the light receiving surface (the short side of the light receiving area). (Corresponding to the direction) is provided for each column of the light receiving regions 142 arranged in a zigzag pattern, and the transparent electrodes 144 are arranged in the horizontal transfer direction of the light receiving surface (corresponding to the long side direction of the light receiving region). 142
It is necessary to commonly provide each (area surrounded by a dotted line). Two
When transferring in phases, two-phase electrodes are assigned to each light receiving region.

Further, when the light receiving region 142 is arranged as shown in FIG. 5, the short side direction of the pixel 141 coincides with the vertical transfer direction of the light receiving surface, so that the incident light is directed to the short side direction of the pixel 141. In order to blur, it is necessary to change the blurring direction of the incident light by the OLPF 13 to the vertical transfer direction of the light receiving surface.

<< Explanation of Second Embodiment >> FIG. 6 is a view showing the schematic arrangement of a solid-state imaging device corresponding to the second embodiment. 6, the solid-state imaging device 2 includes a housing 22 whose opening is closed by a glass substrate 21 and a glass substrate 21 as in the solid-state imaging device 1 corresponding to the first embodiment shown in FIG. And an image pickup chip 24 provided inside the housing 22 so that the light receiving surface faces the glass substrate 21.

Further, in FIG. 6, a plurality of pixels 241 are two-dimensionally arranged on the image pickup chip 24. Each pixel 241 is a rectangle whose length ratio in the long side direction and the short side direction is approximated to “2: 1”, and is 1/1 of the pixel pitch in the long side direction with respect to the short side direction. They are offset by two and are arranged in a zigzag manner, and are arranged substantially in a straight line in the long side direction.

However, in FIG. 6, unlike FIG. 1, each pixel 241 is inclined by 45 degrees with respect to the horizontal transfer direction and the vertical transfer direction of the light receiving surface. The OLPF 23 is the pixel 2
With respect to the short side direction of 41, the incident light is blurred by the pixel pitch in the short side direction. As a result, as shown in FIG. 7, the aperture of each pixel 241 expands in the short side direction of the pixel 241 to form a square shape, and the pixels 241 adjacent in the short side direction overlap with each other.

The sampling points for each pixel 241 are as shown in FIG. FIG. 9 is a diagram showing the configuration of the light receiving region in the second embodiment. In FIG. 9, each light receiving area 242 (area surrounded by a dotted line) has a length ratio in the long side direction and the short side direction of “2: 1” as in the pixel 241 shown in FIG. It is a rectangle that is approximated and is arranged in a zigzag manner by offsetting each half of the pixel pitch in the long side direction in the short side direction, and in the long side direction,
They are arranged almost on a straight line.

However, in FIG. 9, a channel stop 243 is provided for each column (pixel group) of the light receiving regions 242 arranged in a zigzag pattern along the vertical transfer direction of the light receiving surface, and in the case of two-phase driving, the light receiving surface of the light receiving surface is changed. A two-phase transparent electrode 244 is provided for each of the light receiving regions 242 (pixel groups) arranged in zigzag along the horizontal transfer direction. Such a transparent electrode 244
Are supplied with pulse signals φ1A and φ2A for transferring signal charges.

According to the structure shown in FIG. 9, the plurality of light receiving regions 242 are separated by the channel stop 243 into columns arranged in zigzag along the vertical transfer direction of the light receiving surface, and the common transparent electrode 244 is provided. Light-receiving area 24
2 (corresponding to the light receiving regions 242 arranged in zigzag along the horizontal transfer direction of the light receiving surface) can be simultaneously transferred in the vertical transfer direction of the light receiving surface. Therefore, similarly to the existing frame transfer type solid-state imaging device, it is possible to scan the signal charges by the frame transfer method via the storage unit and the horizontal reading unit (not shown).

As described above, in the second embodiment,
An aperture as shown in FIG. 7 can be obtained only by providing a single OLPF 23 for blurring the incident light by the pixel pitch in the short side direction with respect to the short side direction of the light receiving region 242. Therefore, similarly to the first embodiment, it is possible to reduce aliasing due to aliasing of the Nyquist frequency while minimizing a decrease in sharpness, and it is caused by providing a plurality of optical members that blur incident light. It is possible to avoid the conventional problems.

In the second embodiment, the shape of the channel stop 243 and the transparent electrode 244 are different from those of the existing frame transfer type solid-state image pickup device shown in FIG. By using zigzag as described above, scanning of signal charges by a frame transfer method can be easily realized. Furthermore, in the second embodiment, the sample points for each pixel 241 are square grid sample points, as shown in FIG.

In each of the above-described embodiments, a frame transfer type solid-state image pickup device has been described as an example of the solid-state image pickup device of the present invention. By adopting such a frame transfer method, it is possible to use most of the rectangular pixels as an effective light receiving area even though the pixel aspect ratio is an extreme rectangular pixel of about “2: 1”. As a result, it is possible to realize a solid-state imaging device having excellent light receiving efficiency while adopting a rectangular pixel having an extremely high pixel aspect ratio.

The present invention is not limited to such a frame transfer system. For example, the interline transfer method can be adopted. However, when the above configuration is realized by the interline transfer method, since the pixel aspect ratio of the light receiving region has an extreme value, problems such as sensitivity deterioration due to a decrease in the aperture ratio are likely to occur. Conventionally, in order to improve the light receiving efficiency of this interline transfer method, it is often practiced to provide a microlens for each pixel. However, in the solid-state imaging device of the present invention, the pixel aspect ratio is as extreme as “2: 1”, and it is very difficult to design an appropriate microlens.

For example, in the case of forming a microlens in accordance with a pixel shape having a side length of "2: 1", FIG.
An elliptical microlens as shown in (1) can be considered. However, when an elliptical lens is used as a microlens on a rectangular light receiving portion, the light-condensing characteristics are different in the long-side direction and the short-side direction, which causes a problem that the blur does not become round.

In order to avoid such a problem, FIG.
As shown in (2), it is preferable to dispose two microlenses in the long side direction of the pixel (light receiving region). By providing the compound-eye type microlens for the rectangular light-receiving region in this manner, the condensing characteristics of each pixel are substantially isotropic even though the pixel has a rectangular shape with an extreme pixel aspect ratio.

Furthermore, by providing a light-shielding portion in the boundary area of a plurality of microlenses, it is possible to block light from distorted directions, and it is possible to further enhance the isotropy of the light-collecting characteristics of rectangular pixels. become.

Further, in FIG. 10 (2), a common storage section is provided under the compound-eye type microlens. Therefore, the signal charges generated by the incident light of the compound-eye type microlens can be collectively accumulated and added in units of rectangular pixels. As a result, it becomes easy to omit the sequence operation for pixel addition and simplify the transfer sequence of the solid-state imaging device.

Further, in the solid-state image pickup devices 1 and 2 corresponding to the above-mentioned respective embodiments, the OLPFs 13 and 23 are provided. As the OLPF, for example, light incident on the light receiving surface like a diffraction grating is used. Any optical member may be provided as long as it can blur the light in the short side direction of the light receiving region.

Further, in the solid-state image pickup devices 1 and 2 corresponding to the above-described respective embodiments, the glass substrates 11 and 21 close the openings of the housings 12 and 22.
It is also possible to provide a configuration in which the openings of the housings 12 and 22 are closed by the OLPFs 13 and 23 without providing the elements 1 and 21.

Further, in each of the above-described embodiments, the monochrome solid-state image pickup device without the color filter has been described, but the present invention can be similarly applied to a color solid-state image pickup device having a plurality of color filters. Can
False colors caused by aliasing can be reduced. For example, in the solid-state imaging device 1 corresponding to the first embodiment, the color filters of three colors of R, G, and B are arranged in an array as shown in FIG. 11 (2), the apertures are as shown in FIG. 11 (2) by associating each pixel 141 with a column in which the columns in which the B and B color filters are alternately arranged form a stripe).

Such an aperture is a solid-state image pickup device having a two-plate type solid-state image pickup device (an image pickup device provided with only a G color filter and an image pickup device provided with R and B color filters in a checkered pattern). Device), which is equivalent to an aperture when two image pickup elements are shifted by a 1/2 pixel pitch, and is effective for a color solid-state image pickup device.

The color filters provided in each pixel are not limited to the three colors of R, G and B, but the four color filters of Ye, Mg, Cy and G.
Any color type such as color may be used, and the arrangement of the color filters is not limited to the arrangement shown in FIG. 11 (1).

[0044]

As described above, according to the solid-state image pickup device of the present invention, even if the number of optical members that obscure the incident light (including the case of multiplexing) is one, it is caused by the folding of the Nyquist frequency. It is possible to appropriately suppress the defects due to the aliasing, and to suppress the deterioration of the sharpness to the minimum. In the case of a color image pickup element, reduction of false color and prevention of reduction in sharpness can be performed in a well-balanced manner.
Further, it is possible to avoid the conventional problems (cost increase, flare increase, deterioration of aberration characteristics of the optical system, increase of space, etc.) that have been caused by providing a plurality of optical members for blurring incident light.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a solid-state imaging device corresponding to a first embodiment.

FIG. 2 is a diagram showing a state of an aperture in the first embodiment.

FIG. 3 is a diagram showing sample points in the first embodiment.

FIG. 4 is a diagram showing a configuration of a light receiving region in the first embodiment.

FIG. 5 is a diagram showing another configuration of the light receiving region in the first embodiment.

FIG. 6 is a diagram showing a schematic configuration of a solid-state imaging device corresponding to the second embodiment.

FIG. 7 is a diagram showing an aperture according to a second embodiment.

FIG. 8 is a diagram showing sample points in the second embodiment.

FIG. 9 is a diagram showing a configuration of a light receiving region in the second embodiment.

FIG. 10 is a diagram showing a configuration example of a pixel when a microlens is provided.

FIG. 11 is a diagram showing a state of an aperture when a color filter is provided.

[Explanation of symbols]

1, 2 Solid-state imaging device 11, 21 glass substrate 12, 22 housing 13, 23 OLPF 14, 24 Imaging chip 141, 241 pixels 142, 242 light receiving area 143,243 channel stop 144,244 transparent electrodes

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 9/07 H01L 27/14 DF term (reference) 4M118 AA05 AA10 AB01 BA12 BA13 CA08 DA12 DA20 FA07 FA26 GC08 GC09 GC20 GD02 GD04 GD07 HA02 HA23 5C024 CX01 CX11 CX14 CY33 DX01 EX43 EX52 GY03 GZ36 5C065 BB09 BB10 BB13 BB22 CC01 DD06 EE03 EE11

Claims (3)

[Claims] 1. A pixel pitch in the long side direction of the light receiving area with respect to the short side direction of the light receiving area, each having a rectangular light receiving area for generating a signal charge according to light incident on the light receiving surface. A plurality of pixels which are offset by ½ each of which are arranged two-dimensionally, a scanning unit which scans the signal charge and reads the signal charges to the outside, and a plurality of pixels which are provided on the light receiving surface side of the plurality of pixels and are provided on the light receiving surface. An optical member that blurs incident light in the short side direction by a pixel pitch, the light receiving region is a rectangle whose aspect ratio is approximated to “2: 1”, and the plurality of pixels are the light receiving surface. Is separated for each pixel group arranged in one direction, and the signal charges are sequentially transferred in one direction of the light receiving surface, and the scanning unit causes the plurality of pixels to move in one direction of the light receiving surface. Drive for each pixel group arranged in the orthogonal direction,
A solid-state imaging device, characterized in that the signal charges are scanned by a frame transfer method. 2. A pixel pitch in the long side direction of the light receiving area with respect to the short side direction of the light receiving area, each having a rectangular light receiving area for generating a signal charge according to light incident on the light receiving surface. A plurality of pixels which are offset by ½ each of which are arranged two-dimensionally, a scanning unit which scans the signal charge and reads the signal charges to the outside, and a plurality of pixels which are provided on the light receiving surface side of the plurality of pixels and are provided on the light receiving surface. The aspect ratio of the light receiving area is set to "2: 1" by arranging two optical members for blurring the incident light in the short side direction by the pixel pitch and two light receiving areas arranged side by side in the long side direction.
And a storage unit that stores the signal charges generated by the light incident on the two microlenses in the light-receiving region collectively for each of the light-receiving regions. . 3. The solid-state imaging device according to claim 2, further comprising a light-shielding portion that shields a boundary region between two microlenses arranged in the light-receiving region.