JP2515000Y2 - Color image sensor - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION This invention relates to a color image sensor, and more particularly to a linear image sensor.

[0002]

2. Description of the Related Art Color image scanners and color OCRs
In order to realize (optical character reading device), for example, a pixel composed of a photosensitive element having sensitivity to red, a photosensitive element having sensitivity to green, and a photosensitive element having sensitivity to blue (hereinafter,
It is called a "color pixel". ), A color image sensor in which a large number of () are arranged is required.

Conventionally, as a color image sensor of this type, for example, there is one referred to by the applicant as trade name MN3661A. FIG. 3A is a plan view for explaining the relationship between the photosensitive elements of each color of the color image sensor and the color pixels formed by these photosensitive elements.

In this conventional color image sensor, two types of photosensitive elements, that is, a first photosensitive element 13 having a sensitivity to blue and a second photosensitive element 15 having a sensitivity to red are provided on a silicon substrate as a substrate 11. The first photosensitive element rows 17 formed by alternately arranging at the pitch P, and the third photosensitive elements 19 arranged in parallel to the first photosensitive element rows 17 and having sensitivity to green are the first photosensitive element. A second photosensitive element row 21 formed by arranging the same number as the number of photosensitive elements in the row 17 at the pitch P.
It was equipped with. Each photosensitive element 13, 15, 19
The dimension w in each arrangement direction was set to a dimension substantially equivalent to the pitch P. Then, the first photosensitive element 13 and the second photosensitive element 15 which are adjacent to each other in the first photosensitive element row 17 are provided.
And the third photosensitive element 19 arranged in the photosensitive elements 13 and 15 constitute the color pixel 23.

In this color image sensor, the photosensitive element 19 having sensitivity to green can be used as an element for inputting a luminance signal, and the photosensitive element 13 having sensitivity to blue and the photosensitive element 15 having sensitivity to red can be used as an element for color signal input. Can be used as In that case, since the sampling frequency of the color signal is almost half that of the luminance signal, the luminance signal is set to, for example, 400.
Assuming that reading is performed at a DPI (dot per inch) resolution, the color signal reading resolution is 200 DPI. It should be noted that each of these signals is obtained as a spatial integral value of incident light on the corresponding photosensitive element.

[0006]

[Problems to be solved by the device] However, FIG.
In the conventional color image sensor described with reference to (A), the dimension w in the arrangement direction of the photosensitive elements for each color is set to a value substantially equal to the arrangement pitch P of the photosensitive elements, so that the sampling width by one color pixel 23 is set. X becomes a value substantially equal to the original arrangement pitch Y of the color pixels 23 (see FIG. 3A). Therefore, using this color image sensor, for example, as shown in FIG. 3B, a color pattern in which the intensity of red (R) is abruptly changed within the width of the photosensitive element for red. 31 (original), that is, when the color pattern 31 having a finer pattern than the color pixel density is read, the green (G) and blue (B) components can be sampled well, and sensor outputs V _G and V _B are obtained. but the output V _R becomes small (can not be successfully sampling) for spatial integration value becomes smaller for the red (R) component. Therefore, there is a problem in that an image in which a color shift is generated with respect to an actual color pattern is output.

The present invention has been made in view of the above points, and therefore an object of the present invention is to obtain a color image which is less likely to cause color shift than before even when reading a color pattern having a finer pattern than the color pixel density. To provide a sensor.

[0008]

In order to achieve this object, according to the present invention, first photosensitive elements and second photosensitive elements having different spectral sensitivities are alternately arranged at a pitch P on a substrate. And a third photosensitive element arranged in parallel to the first photosensitive element row and having a spectral sensitivity different from those of the first and second photosensitive elements described above are arranged at a pitch P. In the color image sensor including the second photosensitive element array, the size W ₁ of the _first photosensitive element in the column direction and the second photosensitive element array
Yes of the column direction dimension W ₂ each photosensitive element is smaller than the arrangement pitch P of the photosensitive element, a third photosensitive element is defined by two adjacent photosensitive elements of the first photosensitive element array described above It is characterized in that it is provided in a substrate region that is aligned with the range of (W ₁ + W ₂ ) / 2 + P. However, W ₁ and W ₂ may have the same value or different values.

The substrate is usually a silicon substrate. However, the material of the substrate is not the essence of this invention, and may be any material as long as the image sensor can be constructed.

Further, in implementing the present invention, the photosensitive element widths W ₁ and W are set so that the dimension defined by (W ₁ + W ₂ ) / 2 + P is a desired sampling width.
_It is preferable to set ₂ .

[0011]

In accordance with the this invention configuration, arrangement pitches of the first photosensitive element array first array dimension W ₂ of these photosensitive elements of the array dimension W ₁ and second photosensitive elements of the photosensitive element Since the third photosensitive element is arranged so as to be smaller than P and aligned with two adjacent photosensitive elements of the first photosensitive element row, the sampling width of one color pixel is the original arrangement pitch of the color pixels. It is always smaller than (the dimension indicated by Y in FIGS. 3 and 1). Therefore, when reading a color pattern having a pattern finer than the color pixel density, color shift can be prevented as long as the color pattern has a pattern larger than the sampling width.

[0012]

Embodiments of the color image sensor of the present invention will be described below with reference to the drawings. However,
The drawings used in the following description schematically show the dimensions, shapes, and positional relationships of the respective constituents so that the present invention can be understood. Therefore, illustration of constituent components usually included in the color image sensor is omitted.

1. First Embodiment FIG. 1A is a plan view showing a configuration of a color image sensor according to a first embodiment of the present invention, and is a view showing a relationship between a photosensitive element of each color and a color pixel. Further, FIG. 1 (B) shows a case where the color image sensor of the first embodiment is used in FIG.
It is a figure for demonstrating the mode at the time of reading the color pattern 31 shown to (B).

In the color image sensor of the first embodiment, as shown in FIG. 1A, a substrate 11 has a first photosensitive element 13 having a blue sensitivity and a second photosensitive element having a red sensitivity. A first photosensitive element row 17 configured by alternately arranging two kinds of photosensitive elements 15 of 15 at a pitch P, and a third photosensitive element row 17 arranged in parallel with the first photosensitive element row 17 and having a sensitivity to green.
The second photosensitive element array 21 is formed by arranging the photosensitive elements 19 in the same number as the number of photosensitive elements in the first photosensitive element array 17 at the pitch P. Then, the arrangement direction of the dimension W ₂ each sequence dimension W ₁ and the first photosensitive element 15 of the first photosensitive element 13, there as a value smaller than the arrangement pitch P of the photosensitive element, and, third Photosensitive element 19
In the substrate region 41 aligned with the range of (W ₁ + W ₂ ) / 2 + P defined by two adjacent photosensitive elements of the first photosensitive element row 17, in this case, the first photosensitive element 13 (second It is provided at a position side by side with the photosensitive element 15).

Here, the arrangement pitch P of the photosensitive elements is 63.
With the color image sensor with a thickness of 5 μm, when the color pattern is read through the equal-magnification imaging lens system, the luminance signal (green G in this case) can be read at a resolution of 400 DPI.

[0016] Then, the width W ₁ of the first photosensitive element 13, the width W ₂ of the second photosensitive element 15, respectively, W ₁ = W ₂ = 2
When set to 0 μm, the sampling width X is X = P + (W ₁ + W ₂ ) /2=63.5+20=83.
Since it is 5 μm, it can be seen that this color image sensor can read color signals (red and blue) at a resolution of 300 DPI. In the conventional type, both W ₁ and W ₂ are approximately 63.5μ
Since the color signal was set to m, the superiority of this invention can be seen when considering that the color signal could be read only at a resolution of 200 DPI.

Therefore, in the color image sensor of this embodiment, as shown in FIG. 1B, a color pattern 31 finer than 200 DPI and rougher than 300 DPI.
, The sampling outputs V _R , V _G, and V _B that are true to the color pattern can be obtained with the red, blue, and green photosensitive elements, respectively. Therefore, when reading a color pattern having a finer pattern than the color pixel density. In addition, color shift is less likely to occur than before.

The dimension W _{1 of} the first and second photosensitive elements
It can be adjusted to read resolution of a color signal and by changing the W _2, W ₁ and W ₂ may be changed depending on the design.

2. Second Embodiment In the above-described first embodiment, a substrate in which the third photosensitive element 19 is arranged in a range of (W ₁ + W ₂ ) / 2 + P defined by two adjacent photosensitive elements of the first photosensitive element row 17 It was provided in the area 41 in a position aligned with the first photosensitive element 13 (the photosensitive element 15 of the subject 2). However, the third photosensitive element 19 may be located at any position within the substrate region 41. This second embodiment is this example. FIG. 3 is a plan view for explaining the color image sensor of the second embodiment.

In the second embodiment, the third photosensitive element 19 is used.
Is provided in the central portion within the substrate region 41 which is aligned with the range of (W ₁ + W ₂ ) / 2 + P defined by the two adjacent photosensitive elements of the first photosensitive element row 17. However, the number of photosensitive elements in each of the first photosensitive element row 17 and the second photosensitive element row 21 is different.

With the color image sensor of the second embodiment, the same effect as that of the first embodiment can be obtained.

Although the respective embodiments of the color image sensor of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments.

For example, in the above-described embodiment, the first photosensitive element is a photosensitive element having blue sensitivity, the second photosensitive element is a photosensitive element having red sensitivity, and the third photosensitive element is sensitive to green. Although the example in which the photosensitive element having the above is used is described, the arrangement of the photosensitive elements of each color is not limited to this example.

Further, the present invention can be applied to a long color image sensor in which individual color image sensors are connected in multiple stages.

[0025]

As is apparent from the above description, according to the color image sensor of the present invention, the sampling width of the color pixels can be made smaller than the arrangement pitch of the color pixels, so that it is finer than the color pixel density. Even when reading a color pattern having a pattern, it is possible to obtain an image in which color shift is less likely to occur than in the past.

In the contact type color image sensor, since the original is read through the same-magnification optical system, the color pixel pitch can be increased, and as a result, the dimensions W ₁ and W _{2 in} the arrangement direction of the photosensitive elements can be easily changed. , This device is easier to apply.

[Brief description of drawings]

FIG. 1A is a plan view for explaining the configuration of a color image sensor of a first embodiment, and FIG. 1B is a view for explaining the effect of this color image sensor.

FIG. 2 is a plan view for explaining the configuration of a color image sensor of a second embodiment.

FIG. 3A is a plan view for explaining the configuration of a conventional color image sensor, and FIG. 3B is a diagram for explaining the problem.

[Explanation of symbols]

 11: substrate 13: first photosensitive element 15: second photosensitive element 17: first photosensitive element row 19: third photosensitive element 21: second photosensitive element row 23: color pixel 31: color pattern 41: Substrate area where the third photosensitive element is provided X: Sampling width Y: Color pixel pitch

Claims (2)

(57) [Scope of utility model registration request] 1. A first photosensitive element array in which first photosensitive elements and second photosensitive elements having different spectral sensitivities are alternately arranged on a substrate at a pitch P, and a first photosensitive element array is provided on the first photosensitive element array. A second photosensitive element, which is arranged in parallel and has a spectral sensitivity different from that of the first and second photosensitive elements, is arranged at a pitch P.
In the color image sensor including the photosensitive element row of the first photosensitive element, the dimension W ₁ of the first photosensitive element in the column direction and the dimension W ₂ of the second photosensitive element in the column direction are each made smaller than the arrangement pitch P of the photosensitive elements. Yes, the third photosensitive element is the adjacent two of the first photosensitive element row.
A color image sensor characterized in that it is provided in a substrate region that is lined up with a range of (W ₁ + W ₂ ) / 2 + P defined by one photosensitive element (however, W ₁ and W ₂ may have the same value or different values). .). 2. The color image sensor according to claim 1, wherein the photosensitive element widths W ₁ and W ₂ are set such that the dimension defined by (W ₁ + W ₂ ) / 2 + P has a desired sampling width. A color image sensor characterized by being set.