JPH11112888A - Photoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion device with excellent durability for preventing the decline of image quality due to the sticking of photoelectric conversion arrays. SOLUTION: This device is provided with a first photoelectric conversion array 4 and a second photoelectric conversion array 5 in which many picture elements by photoelectric conversion elements are regularly arrayed and is constituted by sticking the arrays 4 and 5 together so as to be adjacent to each other. In this case, among a picture element pitch PI stipulated by a distance between the centroids of the picture elements of the first photoelectric conversion array 4, the picture element pitch P2 stipulated by the distance between the centroids of the picture elements of the second photoelectric conversion array 5 and P3 stipulated by the distance between the centroid of the picture element of the first photoelectric conversion array 4 and the centroid of the picture element of the second photoelectric conversion array 5 at the sticking boundary, it is established that P1=P2 and P3 is roughly (n)-fold of P1 or P2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device used for an image scanner, an X-ray imaging device, etc., and more particularly, to a photoelectric conversion device in which a plurality of photoelectric conversion arrays are bonded so as to be adjacent to each other to enlarge a light receiving area. It concerns the device.

[0002]

2. Description of the Related Art FIG. 8 shows a configuration of a conventional photoelectric conversion device. This figure shows an example used for X-ray imaging. In the figure, reference numeral 1 denotes a light source, that is, an X-ray source for irradiating a subject 2 (in this figure, a human body) with X-rays. Reference numeral 3 denotes a phosphor that converts transmitted X-rays, that is, X-rays having subject information, into visible light. Reference numeral 4 denotes a first photoelectric conversion array for reading subject information light (visible light) from the phosphor 3 and converting the light into an electric signal. Reference numeral 5 denotes a second photoelectric conversion array. The photoelectric conversion arrays 4 and 5 are two-dimensionally and regularly arranged photoelectric conversion elements. The first photoelectric conversion array of 4 and 5
Are arranged adjacent to each other on the six chassis. In general, the chassis 6 is made of a material having a high X-ray absorptivity (such as lead) in order to prevent adverse effects due to scattering or the like.

FIGS. 9 (a) and 9 (b) correspond to FIG.
FIG. 6 is a schematic diagram showing a configuration of a photoelectric conversion element on the photoelectric conversion arrays of FIGS. FIG. 9B is a diagram corresponding to AB in FIG. 9A.
It is sectional drawing at the time of cutting by. In this figure, the photoelectric conversion element is composed of a sensor 8 on a glass substrate 7 and a thin film transistor (TFT) 9. In this figure, the sensor 8
The TFT 9 is formed simultaneously with the amorphous silicon thin film process. In this illustration, the sensor 8 is a MIS
Type sensor. A sensor 8 and a TFT 9 are formed on a glass substrate 7 by a lower metal layer 10, an insulating layer 11, a semiconductor layer 12,
It is formed by sequentially forming and patterning a + layer 13, an upper metal layer 14, and a protection layer (not shown) such as an amorphous silicon nitride film or polyimide.

FIG. 10 is an equivalent circuit showing the operation of the photoelectric conversion element shown in FIG. An electric charge is generated in accordance with the amount of light incident on the sensor 8, and the electric charge is transferred to a reading device (not shown) by the TFT 9 to perform a reading operation.

FIG. 11 shows the photoelectric conversion array of the conventional photoelectric conversion device shown in FIG. 8 when viewed from the X-ray source 1 side.
In the figure, the first photoelectric conversion array 4 and the second photoelectric conversion array 5 are each composed of 5 × 5 photoelectric conversion elements. As shown in the figure, the first photoelectric conversion array 4 and the second photoelectric conversion array 5 are bonded on a chassis 6 so as to be adjacent to each other. FIG. 3 shows a state in which a subject 15 is read over the arrays 4 and 5. Reference numeral 8 denotes a sensor (pixel) in each photoelectric conversion element.

FIG. 12 is a simplified representation of how an image read by the conventional photoelectric conversion device of FIG. 11 is reproduced on a display.

As shown in FIG. 12, the conventional photoelectric conversion device has a problem that a reproduced image is different from an actual image and a step occurs at a boundary of bonding.

In a conventional photoelectric conversion device, as shown in FIG. 13, a photoelectric conversion array formed and patterned on a glass substrate 7 is generally cut along a slice line 16 and bonded to each other. It is.

In order to avoid the above-mentioned problem of the step of the image, the distance d between the photoelectric conversion element (sensor 8) and the slice line 16 must be reduced as shown in FIG. In this case, the photoelectric conversion element (sensor 8) in the vicinity of the slice line becomes defective due to chipping or flaw 17 of the glass or the protective layer at the time of cutting, or moisture or impurities invade from the flaw of the protective layer and cause corrosion. Becomes
There was a problem such as.

[0010]

That is, the following problems have occurred in a conventional photoelectric conversion device in which a plurality of photoelectric conversion arrays are arranged adjacent to each other. When an image is reproduced, a step is generated in the image at the boundary of the bonding, which degrades the image quality. A defect occurs in the photoelectric conversion element due to a scratch at the time of cutting or the like.
Alternatively, moisture and impurities enter from the cut surface, causing corrosion and characteristic changes.

[Object of the Invention] An object of the present invention is to provide a photoelectric conversion device which is improved in deterioration of image quality due to bonding of a photoelectric conversion array and has excellent durability.

[0012]

According to the present invention, as a means for solving the above-mentioned problems, a first photoelectric conversion array in which a large number of pixels are regularly arranged by photoelectric conversion elements;
In the photoelectric conversion device in which the photoelectric conversion arrays are bonded together so as to be adjacent to each other, a pixel pitch P1 defined by a distance between the centers of gravity of the pixels of the first photoelectric conversion array;
The pixel pitch P2 defined by the distance between the centers of gravity of the pixels of the second photoelectric conversion array, and the distance between the center of gravity of the pixels of the first photoelectric conversion array and the center of gravity of the pixels of the second photoelectric conversion array at the bonding boundary The following relationship is established for P3 defined by the distance: P1 = P2 P3 is approximately n times P1 or P2 (where n is a natural number (n = 1, 2, 3,...)). A conversion device is provided.

Further, in order to obtain a good image as aimed by the present invention, P3 must be within 30% of P1 (or P2), that is, (n−0.3) × P1 ≦ P3 It is desirable that ≦ (n + 0.3) × P1.

Further, when applied to an X-ray photographing apparatus or the like and reproducing an image to obtain an image without a step at the bonding boundary, P3 is 2 times smaller than P1 (or P2).
It is ideal that the variation is within 0%, that is, (n−0.2) × P1 ≦ P3 ≦ (n + 0.2) × P1.

The present invention has the following means in order to solve the above problems.

The photoelectric conversion device, wherein n = 2.

Further, the photoelectric conversion device is characterized in that the centers of gravity of the pixels of the first photoelectric conversion array and the second photoelectric conversion array are respectively displaced toward the bonded portion.

Further, the pixel shape of the first photoelectric conversion array and the pixel shape of the second photoelectric conversion array are the same.

Further, the pixel shape of the first photoelectric conversion array and the pixel shape of the second photoelectric conversion array have a mirror image relationship with respect to a bonding boundary.

Further, each pixel of the first photoelectric conversion array and the second photoelectric conversion array has a photoelectric conversion element and a thin film transistor.

Further, the photoelectric conversion element and the thin film transistor are formed by an amorphous silicon process.

[0022] Further, the thin film transistor is arranged at a position far from the bonding boundary.

The photoelectric conversion device is characterized in that the photoelectric conversion element is a PIN type photodiode.

The photoelectric conversion device is characterized in that the photoelectric conversion element is a MIS type photodiode.

[0025] The photoelectric conversion device is characterized in that four photoelectric conversion arrays are bonded so as to be adjacent to each other.

Further, the photoelectric conversion device is characterized in that four pixels of a normal image, a mirror image, a half rotation of the normal image and a half rotation of the mirror image are pasted together so as to be adjacent to each other.

The distance P3 between the pixel centroids of the bonding boundary is approximately twice as large as P1 or P2, and information on a pixel corresponding to the bonding boundary is calculated based on surrounding pixel information. And a means for interpolating.

[Operation] According to the above means of the present invention,
It is possible to realize a photoelectric conversion device which is improved in deterioration of image quality due to bonding of a photoelectric conversion array and has excellent durability.

That is, according to the present invention, the aforementioned P
In P1, P2, and P3, P1 is equal to P2, and P3 is approximately n times P1 or P2 (where n is a natural number (1, 2, 3,...)), So that the image quality obtained by bonding photoelectric conversion arrays is obtained. And a photoelectric conversion device having excellent durability can be realized.

Further, in order to obtain a good image as intended by the present invention, P3 varies within 30% of P1 (or P2), that is, (n−0.3) × P1 ≦ P3 It is desirable that ≦ (n + 0.3) × P1.

Further, when applied to an X-ray photographing apparatus and the like, and an image is reproduced, to obtain an image without a step at a bonding boundary, P3 is 20 times larger than P1 (or P2).
%, That is, (n−0.2) × P1 ≦ P3 ≦ (n + 0.2) × P1 is ideal.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] FIG. 1 is a schematic top view showing a photoelectric conversion device according to a first embodiment of the present invention. Components having the same functions as those of the conventional example are described using the same reference numerals. In FIG. 1, reference numeral 8 denotes a sensor (pixel) such as a PIN photodiode or a MIS photodiode. Reference numerals 4 and 5 denote photoelectric conversion arrays having a configuration in which photoelectric conversion elements are two-dimensionally arranged, and are bonded on the chassis 6 so as to be adjacent to each other.

FIG. 2 is an enlarged view of a bonding boundary of the photoelectric conversion device of FIG. P1 is a pixel pitch defined by the distance between the centers of gravity of the pixels of the first photoelectric conversion array 4. Similarly, P2 is a pixel pitch defined by the distance between the centers of gravity of the pixels of the second photoelectric conversion array 5. MIS as shown in FIG.
In the case of a type sensor, the center of gravity of the n + layer portion of the sensor (pixel) 8 is the sensor center of gravity. P3 is the distance between the centers of gravity of the pixels at the bonding boundary. In this embodiment, P1 = P2 P3 is substantially the same as P1 or P2 (that is, P3 = n
× P1 = 1 × P1, n = 1) in the photoelectric conversion device.

Further, in order to prevent the image from being affected even when P3 varies due to a variation in the bonding process, the error of P3 is preferably within 30% of P1 or P2.

Further, when applied to an X-ray imaging apparatus, etc.,
When an image is reproduced, in order to obtain a good image without a step at the bonding boundary, the error of P3 is P1 and P2.
Ideally, it is within 20%.

FIG. 3 shows the object 7 of FIG.
Is read and the image is reproduced. Even at the boundary of the photoelectric conversion array, the pixel pitch P1 =
Since P2 = P3 is approximately satisfied, no step occurs at the bonding boundary after image reproduction, as shown in FIG.

[Second Embodiment] FIG. 4 is a schematic view of a second embodiment of the photoelectric conversion device according to the present invention, in which the bonding boundary between the first photoelectric conversion array and the second photoelectric conversion array is shown. It is shown enlarged. In this embodiment, the distance between the sensor (pixel) centroids at the boundary of the photoelectric conversion array is approximately P3 = 2 × P1 (or P2) (that is, when n = 2) as shown in the figure. I have. In the same manner as in the first embodiment described above, even if P3 fluctuates due to the bonding process, P3 is 30% of P1 (or P2) so as not to affect the image.
It is desirable that the following is satisfied: 1.7 × P1 ≦ P3 ≦ 2.3 × P1.

Further, when applied to an X-ray imaging apparatus, etc.
When an image is reproduced, P3 is set to P1 (or P2) in order to obtain a good image without any step at the bonding boundary.
Is ideally within 1.8% P1 ≦ P3 ≦ 2.2 × P1.

The images corresponding to E in FIGS. 4 and 5 are calculated and interpolated by an image processing device (not shown) based on the sensor outputs in FIGS. By appropriately performing the image processing, it is possible to reproduce an image with reduced steps as shown in FIG.

As such means for interpolating, there are means such as interpolating with adjacent pixel data; interpolating with the average value or weighted average value of surrounding pixels.

[Third Embodiment] FIG. 6 is a block diagram of a third embodiment of the photoelectric conversion device of the present invention. In the figure, 8
Denotes a sensor in the photoelectric conversion element (corresponding to the sensor 8 in FIG. 9), 9
Schematically shows a TFT (corresponding to TFT 9 in FIG. 9) in the photoelectric conversion element. In this embodiment, similarly to the above-described second embodiment, P3 is set to approximately 2 × P1 (or P2), and the shape of the photoelectric conversion element is affixed between the first photoelectric conversion array and the second photoelectric conversion array. The mirroring reversal is applied to the alignment boundary. With such a configuration, the distance d from the slice line to the sensor (pixel) 8 can be reduced, and the reliability can be improved.

When the four photoelectric conversion arrays are bonded so as to be adjacent to each other, similarly, the pixel shape is a normal image, a mirror image, a half rotation of the normal image, and a half rotation of the mirror image. The same effect can be obtained by bonding the four sheets so that they are adjacent to each other.

[Fourth Embodiment] FIG. 7 is a block diagram of a fourth embodiment of the photoelectric conversion device of the present invention. As shown in the figure, in the present invention, four photoelectric conversion arrays are bonded together. In this embodiment, the TFT 9 is disposed inside the substrate with respect to the sensor 8 as shown.
Generally, a TFT has a large applied electric field as compared with a sensor, and is liable to cause a problem such as corrosion, and when it is generated, it becomes a line defect instead of a point defect. With a configuration in which the TFT is separated from the bonding boundary as in the present embodiment, a photoelectric conversion device without deterioration in image quality and reliability at the boundary can be realized.

[0045]

As described above, according to the present invention,
In a photoelectric conversion device in which a plurality of photoelectric conversion arrays in which a large number of pixels are regularly arranged by photoelectric conversion elements are bonded so as to be adjacent to each other, deterioration in image quality due to bonding of the photoelectric conversion arrays is improved and durability is improved. A photoelectric conversion device with excellent performance can be realized.

That is, according to the present invention, the first photoelectric conversion array in which a large number of pixels by the photoelectric conversion elements are regularly arranged and the second photoelectric conversion array are bonded so as to be adjacent to each other. In the photoelectric conversion device, a pixel pitch P1 defined by the distance between the centers of gravity of the pixels of the first photoelectric conversion array, a pixel pitch P2 defined by the distance between the centers of gravity of the pixels of the second photoelectric conversion array, and a bonding boundary P3 defined by the distance between the center of gravity of the pixel of the first photoelectric conversion array and the center of gravity of the pixel of the second photoelectric conversion array in the following relationship: P1 = P2 P3 is approximately n times P1 or P2 ( However, n is a natural number (1, 2, 3,...), And the photoelectric conversion device is characterized in that deterioration of image quality due to bonding of the photoelectric conversion array is improved and durability is excellent. It can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a photoelectric conversion device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a bonding boundary portion of the photoelectric conversion array according to the first embodiment of the present invention.

FIG. 3 is a reproduced image of the photoelectric conversion device according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram of a photoelectric conversion device according to a second embodiment of the present invention.

FIG. 5 is a reproduced image of the photoelectric conversion device according to the second embodiment of the present invention.

FIG. 6 is a schematic diagram of a photoelectric conversion device according to a third embodiment of the present invention.

FIG. 7 is a schematic diagram of a photoelectric conversion device according to a fourth embodiment of the present invention.

FIG. 8 is a schematic diagram of a conventional photoelectric conversion device.

FIG. 9 is a configuration diagram and a cross-sectional view of a photoelectric conversion element of a conventional photoelectric conversion device.

FIG. 10 is an equivalent circuit diagram of a conventional photoelectric conversion element.

FIG. 11 is a schematic view of a conventional photoelectric conversion device.

FIG. 12 is a reproduced image of a conventional photoelectric conversion device.

FIG. 13 is a substrate image diagram of a conventional photoelectric conversion array.

FIG. 14 is an enlarged view of a bonding boundary portion of a conventional photoelectric conversion array.

[Explanation of symbols]

 Reference Signs List 1 light source 2 subject 3 phosphor 4 first photoelectric conversion array 5 second photoelectric conversion array 6 chassis 7 glass substrate 8 sensor 9 TFT 10 lower metal layer 11 insulating layer 12 semiconductor layer 13 n + layer 14 upper metal layer 16 slice line 17 Lack of protective layer

Claims (13)

[Claims] 1. A first photoelectric conversion array in which a large number of pixels by photoelectric conversion elements are regularly arranged, and a second photoelectric conversion array, wherein the first and second photoelectric conversion arrays are adjacent to each other. The pixel pitch P1 defined by the distance between the centers of gravity of the pixels of the first photoelectric conversion array, and the distance defined between the centers of gravity of the pixels of the second photoelectric conversion array P1 defined by the distance between the center of gravity of the pixels of the first photoelectric conversion array and the center of gravity of the pixels of the second photoelectric conversion array at the bonding boundary, the following relationship: = P2 P3 is a photoelectric conversion device in which P3 is approximately n times P1 or P2 (where n is a natural number (1, 2, 3,...)). 2. The photoelectric conversion device according to claim 1, wherein n = 2. 3. The first photoelectric conversion array and the second photoelectric conversion array.
2. The photoelectric conversion device according to claim 1, wherein the centers of gravity of the pixels of the photoelectric conversion array are displaced toward the bonding portion. 4. The photoelectric conversion device according to claim 1, wherein a pixel shape of said first photoelectric conversion array and a pixel shape of said second photoelectric conversion array are the same. 5. The pixel according to claim 1, wherein the pixel shape of the first photoelectric conversion array and the pixel shape of the second photoelectric conversion array are mirror images with respect to a bonding boundary. Photoelectric conversion device. 6. The first photoelectric conversion array and the second photoelectric conversion array.
2. The photoelectric conversion device according to claim 1, wherein each pixel of the photoelectric conversion array has a photoelectric conversion element and a thin film transistor. 7. The photoelectric conversion device according to claim 6, wherein the photoelectric conversion element and the thin film transistor are formed by an amorphous silicon process. 8. The photoelectric conversion device according to claim 6, wherein the thin film transistor is disposed at a position far from the bonding boundary. 9. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion element is a PIN type photodiode. 10. The photoelectric conversion device according to claim 1, wherein said photoelectric conversion element is a MIS photodiode. 11. The photoelectric conversion array according to claim 1, wherein the four photoelectric conversion arrays are bonded so as to be adjacent to each other.
The photoelectric conversion device as described in the above. 12. The pixel shape according to claim 11, wherein a normal image, a mirror image, 正 rotation of the normal image, and 鏡 rotation of the mirror image are bonded so as to be adjacent to each other. Photoelectric conversion device. 13. A distance P3 between pixel centroids of the bonding boundary is approximately twice P1 or P2, and information on a pixel corresponding to the bonding boundary is calculated based on surrounding pixel information. 2. The photoelectric conversion device according to claim 1, further comprising means for performing interpolation.