Image capturing apparatus
阅读说明:本技术 拍摄装置 (Image capturing apparatus ) 是由 盐田昌弘 田口滋也 饭塚邦彦 芦田伸之 于 2019-07-04 设计创作,主要内容包括:拍摄装置(100)具有以矩阵状配置的多个像素(110),该像素(110)具有对在传感器元件(111)中已积蓄的电荷的输出进行控制的开关元件(112),同一列的像素被划分为区块(120),区块具有对输出进行控制的区块开关元件(122)。(An imaging device (100) is provided with a plurality of pixels (110) arranged in a matrix, wherein the pixels (110) are provided with switching elements (112) for controlling the output of charges stored in sensor elements (111), the pixels in the same column are divided into blocks (120), and the blocks are provided with block switching elements (122) for controlling the output.)
1. A camera device is characterized by comprising:
a plurality of pixels arranged in a matrix, each pixel including a sensor element for accumulating charges corresponding to an amount of radiation and a switching element for controlling an output of the charges accumulated in the sensor element,
the pixels belonging to the same column are divided into blocks composed of a plurality of pixels,
the block is provided with a block switching element for controlling the output of the electric charge outputted from the switching element in the block.
2. The camera according to claim 1,
there is also a row selection circuit for sequentially selecting the pixels of each row,
the block switching elements in the block are controlled to:
the block switching element is turned on during a period in which a column to which the pixel in the block belongs is selected;
the block switching element is turned off during a period in which a column other than the column to which the pixel belongs in the block is selected.
3. The camera according to claim 1,
the block is provided with a block output line for outputting electric charges from each switching element in the block.
4. The camera according to claim 3,
the pixels in the block are arranged with the block output line interposed therebetween.
5. The camera according to claim 2,
the block is provided with a block output line for outputting electric charges from each switching element in the block.
6. The camera according to claim 5,
the pixels in the block are arranged with the block output line interposed therebetween.
7. The photographing apparatus according to any one of claims 1 to 6,
there is also a readout circuit that converts the amount of electric charge output from the block switching elements into an electric signal.
Technical Field
The present invention relates to an imaging apparatus, and more particularly to an X-ray imaging apparatus using a flat panel detector.
Background
As the sensor element that outputs an electric signal corresponding to the amount of incident radiation, particularly X-rays, a direct conversion type that directly converts X-rays into an electric signal or an indirect conversion type that converts X-rays into light with a scintillator and further into an electric signal with a photoelectric conversion element is used. As disclosed in patent document 1, a panel for X-ray image capturing has been developed in which a plurality of pixels using such X-ray sensor elements are arranged in a two-dimensional matrix on a substrate.
In this panel, the gate terminal of the tft (thin film transistor) as a switching element in each pixel is commonly connected to a row selection line (gate drive line) for each row of the two-dimensional matrix. The respective row select lines are connected to the line output terminals of the gate drivers. The drain terminals of the TFTs in the respective pixels are commonly connected to an output line (data signal line) for each column of the two-dimensional matrix. Each output line is connected to each line input terminal of the multiplexer via a Read circuit which is an integration circuit including a Read-out Amplifier (Read-out Amplifier), a capacitor for a time constant, and a switch for reset.
Disclosure of Invention
Technical problem to be solved by the invention
In such an imaging device, in order to increase the size of the applicable region and improve the performance, it is desired to increase the definition and the size, and a large increase in the number of pixels is required. For example, in the case of a pixel having 1000 × 1000 pixels, 1000 switching elements are connected in parallel with 1 readout circuit. Therefore, the capacitance due to the switching element on the output line side (input side of the readout circuit) as viewed from the readout circuit also increases greatly. Such a capacitance of the output line is one of factors that deteriorate the performance of the X-ray image panel, and is related to thermal noise of the output line. Accordingly, the thermal noise of the output line increases as the number of pixels increases, and the performance (SN ratio) of the X-ray image panel deteriorates, which is a problem when the panel is increased in size.
An object of one embodiment of the present invention is to provide an imaging device capable of suppressing noise in an image.
Means for solving the problems
(1) One embodiment of the present invention is an imaging apparatus including a plurality of pixels arranged in a matrix, each of the plurality of pixels including a sensor element that accumulates charges corresponding to an amount of radiation, and a switching element that controls an output of the charges accumulated in the sensor element, wherein the pixels belonging to a same column are divided into blocks each including a plurality of pixels, and a block switching element that controls an output of the charges output from the switching element in each of the blocks is provided in each of the blocks.
(2) Further, an imaging device according to an embodiment of the present invention has, in addition to the configuration of the above (1), a row selection circuit that sequentially selects the pixels in each row, and the block switching elements in the block are controlled such that: in a period in which a row to which a pixel in the block belongs is selected, the pixel is turned on; the block is turned off while the columns other than the column to which the pixels belong are selected.
(3) In addition to the configuration of (1) or (2), the imaging device according to an embodiment of the present invention is configured such that a block output line that outputs charges from each switching element in the block is provided in the block.
(4) In addition to the configuration of (3), an imaging device according to an embodiment of the present invention is configured such that pixels in the block are arranged with the block output line interposed therebetween.
(5) Further, an imaging device according to an embodiment of the present invention has a readout circuit that converts the amount of electric charge output from the block switching element into an electric signal, in addition to any one of the configurations (1) to (4) described above.
Effects of the invention
According to one aspect of the present invention, an imaging apparatus capable of suppressing noise of an image can be realized.
Drawings
Fig. 1 is a diagram showing a circuit configuration of an imaging device according to a first embodiment of the present invention.
Fig. 2 is a schematic diagram showing the arrangement of pixels in the imaging device according to the first embodiment of the present invention.
Fig. 3 is a timing chart showing the operation of the imaging apparatus according to the first embodiment of the present invention.
Fig. 4 is a schematic diagram showing the arrangement of pixels in an imaging device according to a second embodiment of the present invention.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the materials, shapes, relative arrangements, processing methods, and the like of the structures described in the embodiments are merely examples, and the scope of the present invention should not be construed as being limited thereto. The drawings are schematic, and the scale and shape of the dimensions are different from those of reality. In the drawings, the same or corresponding components are sometimes denoted by the same reference numerals.
[ first embodiment ]
A first embodiment of the present invention will be described with reference to fig. 1 to 3.
(construction of the image pickup apparatus 100)
Fig. 1 is a diagram showing a circuit configuration of an
The gate terminals of the
The
In the present embodiment, the
The gate terminals of the
The drain terminals of the
Fig. 2 is a diagram schematically showing the arrangement of pixels in the
In the present embodiment, a
(operation of imaging device 100)
Next, the operation of the
The
In addition, the
For example, the
That is, the
By controlling the switching
The switching
Accordingly, the electric charge accumulated in the
When the period of row selection in the
In this way, the amount of X-rays irradiated to each
(Effect of the photographing apparatus 100)
For comparison, X-ray image data was acquired using an imaging device (comparative example) to which the related art is applied, having a circuit configuration of 1000 rows and 1000 columns, which is of the same scale as the present embodiment. Here, the conventional technique is a technique of not dividing pixels of each column into blocks. In the imaging device of the comparative example, noise is significantly expressed, the contrast of the image is reduced, and the image quality is significantly deteriorated, as compared with the case of using the
This difference is shown for the following reason. The respective switching elements and block switching elements have a gate-drain capacitance Cs. Therefore, in an imaging device to which the conventional technique is applied, the capacitance on the input side (capacitance of an output line) is viewed from the readout circuit of each column and is proportional to the number of pixels (switching elements) connected to each column. If the imaging device is an imaging device with a circuit scale of not large and a number of rows of 100, the capacitance of the output line is 100 Cs. On the other hand, if the number of columns is 1000, the capacitance of the output line becomes about 1000Cs, and the number of pixels increases greatly with the increase in the scale of the number of pixels.
The capacitance of the output line is related to the noise level when the
On the other hand, in the
[ second embodiment ]
An imaging device according to a second embodiment of the present invention will be described. The present embodiment is different from the
Fig. 4 is a diagram schematically showing the arrangement of pixels in the
Unlike the
In the
In this embodiment, the arrangement of pixels is geometrically 1000 rows and 1000 columns, but the circuit configuration is 2000 rows and 500 columns. Thus, 500 readout circuits are required corresponding to the number of columns. Compared to the
In the present embodiment, since the
In the present embodiment, as in the first embodiment, the
(operation of imaging device 200)
In the present embodiment, the operation may be performed in the same manner as the
(Effect of the photographing device 200)
In the
The present invention is not limited to the above embodiments, and various modifications can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention. Further, by combining the technical methods disclosed in the respective embodiments, new technical features can be formed.
Description of the reference numerals
100. 200 shooting device
110. 210 pixel
111 sensor element
112. 212 switching element
120. 220 block
121. 221 block output line
122. 222 block switch element
130 row selection circuit
131. 231 row select line
140 block selection circuit
141. 241 block selection line
150 readout circuit
151. 251 output line
160 multiplexer
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