Radiation detector

Abstract

A radiation detector of an embodiment of the present invention includes: a plurality of control lines extending in a first direction; a plurality of data lines extending in a second direction orthogonal to the first direction; photoelectric conversion sections respectively provided in a plurality of regions divided by the plurality of control lines and the plurality of data lines; a plurality of noise detection sections arranged outside a region in which the plurality of photoelectric conversion sections are provided; a control circuit that inputs a control signal to a first thin film transistor respectively provided in the plurality of photoelectric conversion sections and a second thin film transistor respectively provided in the plurality of noise detection sections; a signal detection circuit that reads an image data signal from the plurality of photoelectric conversion sections and a noise signal from the plurality of noise detection sections; and an image construction circuit that constructs a radiation image based on the read image data signal and the read noise signal. The radiation detector becomes at least any one of the following three cases: the signal detection circuit does not read the image data signal from the photoelectric conversion section adjacent to the noise detection section; the image construction circuit does not use the image data signal read from the photoelectric conversion section adjacent to the noise detection section when constructing the radiation image; and the photoelectric conversion section adjacent to the noise detection section is not electrically connected to at least any one of the control circuit and the signal detection circuit.

Description

Technical Field

[0001] Embodiments of the present invention relate to a radiation detector. Background Technology

[0002] An example of a radiation detector includes an X-ray detector. An X-ray detector may include, for example, an array substrate having multiple photoelectric conversion units and a scintillator disposed on the multiple photoelectric conversion units to convert X-rays into fluorescence. Furthermore, the photoelectric conversion units may include a photoelectric conversion element that converts fluorescence from the scintillator into signal charge, a thin-film transistor that switches the storage and release of signal charge, and a storage capacitor that stores the signal charge.

[0003] Typically, an X-ray detector constructs an X-ray image as follows: First, the incident X-ray is identified using an externally input signal. Then, after a predetermined time, the thin-film transistors of the photoelectric conversion unit are turned on, and the stored signal charge is read as image data signals. Finally, an X-ray image is constructed based on the values ​​of the image data signals read from each photoelectric conversion unit.

[0004] However, the image data signal value read from each photoelectric conversion unit contains a value corresponding to the X-ray dose and a value corresponding to noise. Therefore, when constructing an X-ray image, an offset processing (offset correction) is performed by subtracting the noise-corresponding value from the image data signal value read from each photoelectric conversion unit.

[0005] In this case, the noise can be broadly categorized into random noise and transverse noise. Random noise is uniformly distributed throughout the X-ray image. On the other hand, transverse noise appears as stripes in the horizontal or vertical direction. Therefore, transverse noise is more noticeable than random noise, and thus requires reduction.

[0006] To reduce this lateral noise, the following technique is proposed: multiple noise detection units that do not generate signal charge when X-rays are incident are set up, and lateral noise is detected by these multiple noise detection units. The multiple noise detection units are arranged outside the area (effective pixel area) where multiple photoelectric conversion units are located.

[0007] Multiple noise detection units can be formed together with multiple photoelectric conversion units using semiconductor manufacturing processes. However, since the noise detection unit, which does not generate signal charge, has a different structure than the photoelectric conversion unit, which generates signal charge, the process conditions such as dry etching and wet etching differ in the region where multiple photoelectric conversion units are provided and in the region where multiple noise detection units are provided.

[0008] At the boundaries of regions with different process conditions, the dimensions of the formed elements are prone to change. Therefore, in photoelectric conversion units installed near the boundary between regions with multiple photoelectric conversion units and regions with multiple noise detection units, deviations in image characteristics or broken lines due to changes in dimensions are likely to occur, which may reduce the quality of X-ray images.

[0009] Therefore, there is a need to develop a technology that can detect noise while maintaining the quality of X-ray images.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 2011-97452 Summary of the Invention

[0013] The technical problem that the invention aims to solve

[0014] The problem to be solved by the present invention is to provide a radiation detector that can detect noise and maintain the quality of radiation images.

[0015] Technical solutions to solve technical problems

[0016] The radiation detector involved in the embodiment includes: a plurality of control lines extending along a first direction; a plurality of data lines extending along a second direction orthogonal to the first direction; photoelectric conversion units respectively disposed in a plurality of regions divided by the plurality of control lines and the plurality of data lines; a plurality of noise detection units arranged outside the regions where the plurality of photoelectric conversion units are disposed; a control circuit that inputs control signals to first thin-film transistors respectively disposed in the plurality of photoelectric conversion units and second thin-film transistors respectively disposed in the plurality of noise detection units; a signal detection circuit that reads image data signals from the plurality of photoelectric conversion units and reads noise signals from the plurality of noise detection units; and an image composition circuit that constructs a radiation image based on the read image data signals and the read noise signals. The radiation detector is in at least one of the following three situations: the signal detection circuit does not read the image data signal from the photoelectric conversion unit adjacent to the noise detection unit; the image composition circuit does not use the image data signal read from the photoelectric conversion unit adjacent to the noise detection unit when constructing the radiation image; and the photoelectric conversion unit adjacent to the noise detection unit is not electrically connected to at least one of the control circuit and the signal detection circuit. Attached Figure Description

[0017] Figure 1 This is a schematic three-dimensional diagram used to illustrate an X-ray detector.

[0018] Figure 2 This is a block diagram of an X-ray detector.

[0019] Figure 3 This is the circuit diagram of the array substrate.

[0020] Figure 4 This is a schematic top view used to illustrate the noise detection unit.

[0021] Figure 5 This is a schematic top view used to illustrate the noise detection unit.

[0022] Figure 6 (a) and (b) are schematic top views illustrating the configuration of an area where multiple noise detection units are provided.

[0023] Figure 7 This is a schematic top view illustrating the configuration of the noise detection unit involved in other embodiments.

[0024] Figure 8 This is a schematic top view illustrating the configuration of the noise detection unit involved in other embodiments.

[0025] Figure 9 (a) Figure 9 (b) is a schematic top view illustrating the configuration of an area where multiple noise detection units are provided.

[0026] Figure 10 This is a schematic top view illustrating the noise detection unit involved in other embodiments.

[0027] Figure 11 This is a schematic top view illustrating the noise detection unit involved in other embodiments.

[0028] Figure 12 This is a schematic top view illustrating the configuration of an area where multiple noise detection units are provided. Detailed Implementation

[0029] The embodiments will now be illustrated with reference to the accompanying drawings. Furthermore, in each drawing, the same reference numerals are used to denote the same structural elements, and detailed descriptions are omitted where appropriate.

[0030] The radiation detector described in this embodiment can be applied to various types of radiation, including X-rays and gamma rays. Here, as an example, we will use X-rays, a representative type of radiation, for illustration. Therefore, by replacing "X-rays" with "other types of radiation" in the following embodiments, it can also be applied to other types of radiation.

[0031] The X-ray detector 1 shown below is an X-ray planar sensor that detects radiographic images, i.e., X-ray images.

[0032] While the X-ray detector 1 can be used for general medical or non-destructive examinations, its application is not limited.

[0033] Figure 1 This is a schematic three-dimensional diagram used to illustrate X-ray detector 1.

[0034] in addition, Figure 1 In the drawing, the offset lines 2c3, etc., are omitted.

[0035] Figure 2 This is a block diagram of X-ray detector 1.

[0036] Figure 3 This is the circuit diagram of array substrate 2.

[0037] like Figures 1-3 As shown, the X-ray detector 1 includes, for example, an array substrate 2, a signal processing circuit 3, an image forming circuit 4, and a scintillator 5.

[0038] The array substrate 2 converts the fluorescence (visible light) obtained from X-rays through the scintillator 5 into electrical signals.

[0039] The array substrate 2 includes, for example, a substrate 2a, a photoelectric conversion unit 2b, a control line (or gate line) 2c1, a data line (or signal line) 2c2, a bias line 2c3, and a noise detection unit 2g.

[0040] Furthermore, the number of photoelectric conversion unit 2b, control line 2c1, data line 2c2, bias line 2c3, and noise detection unit 2g are not limited to the example shown.

[0041] The substrate 2a is plate-shaped and is formed of a light-transmitting material such as alkali-free glass.

[0042] Multiple photoelectric conversion units 2b are disposed on one surface of substrate 2a.

[0043] The photoelectric conversion unit 2b is rectangular and is disposed in multiple regions divided by multiple control lines 2c1 and multiple data lines 2c2. The multiple photoelectric conversion units 2b are arranged in a matrix.

[0044] In addition, a photoelectric conversion unit 2b corresponds to a pixel in an X-ray image.

[0045] Each of the multiple photoelectric conversion units 2b is provided with, for example, a photoelectric conversion element 2b1 and a thin-film transistor (TFT) 2b2 (equivalent to an example of a first thin-film transistor) as a switching element. Furthermore, as... Figure 3 As shown, a storage capacitor 2b3 can be provided to store the signal charge converted in the photoelectric conversion element 2b1. The storage capacitor 2b3 is, for example, in the form of a plate and can be disposed below each thin-film transistor 2b2. The photoelectric conversion element 2b1 can also serve as the storage capacitor 2b3, depending on its capacitance.

[0046] The photoelectric conversion element 2b1 can be, for example, a photodiode.

[0047] Thin-film transistor 2b2 performs switching between storing and releasing the charge generated by fluorescence incident on photoelectric conversion element 2b1. Thin-film transistor 2b2 has a gate electrode 2b2a, a drain electrode 2b2b, and a source electrode 2b2c. The gate electrode 2b2a of thin-film transistor 2b2 is electrically connected to the corresponding control line 2c1. The drain electrode 2b2b of thin-film transistor 2b2 is electrically connected to the corresponding data line 2c2. The source electrode 2b2c of thin-film transistor 2b2 is electrically connected to the corresponding photoelectric conversion element 2b1 (electrode 2b1b) and the storage capacitor 2b3. Furthermore, the anode side of photoelectric conversion element 2b1 and the storage capacitor 2b3 are electrically connected to the corresponding bias line 2c3.

[0048] In other words, the thin-film transistor 2b2 is electrically connected to the data line 2c2 corresponding to the corresponding control line 2c1. The electrode 2b1b on the substrate 2a side of the photoelectric conversion element 2b1 is electrically connected to the thin-film transistor 2b2 (see reference). Figure 5 , Figure 7 , Figure 8 ).

[0049] Multiple control lines 2c1 can be arranged parallel to each other at specified intervals. Control lines 2c1 extend, for example, along the row direction (equivalent to an example of the first direction).

[0050] A control line 2c1 is electrically connected to one of a plurality of wiring pads 2d1 disposed near the periphery of the substrate 2a. A wiring pad 2d1 is electrically connected to one of a plurality of wirings disposed on the flexible printed circuit board 2e2. The other end of the plurality of wirings disposed on the flexible printed circuit board 2e1 is electrically connected to a control circuit 31 disposed in the signal processing circuit 3.

[0051] Multiple data lines 2c2 are arranged parallel to each other at specified intervals. The data lines 2c2 extend, for example, along a column direction orthogonal to the row direction (an example of a second direction).

[0052] A data line 2c2 is electrically connected to one of a plurality of wiring pads 2d2 disposed near the periphery of the substrate 2a. A wiring pad 2d2 is electrically connected to one of a plurality of wirings disposed on the flexible printed circuit board 2e2. The other end of the plurality of wirings disposed on the flexible printed circuit board 2e2 is electrically connected to a signal detection circuit 32 disposed in the signal processing circuit 3.

[0053] The bias line 2c3 is set parallel to the data line 2c2 between the data lines 2c2.

[0054] The bias line 2c3 is electrically connected to a bias power supply (not shown). This bias power supply (not shown) can be, for example, located in the signal processing circuit 3.

[0055] Furthermore, bias line 2c3 is not necessary and can be set as needed. Without bias line 2c3, the anode side of photoelectric conversion element 2b1 and storage capacitor 2b3 are electrically connected to ground instead of being electrically connected to bias line 2c3.

[0056] The control line 2c1, data line 2c2, and bias line 2c3 can be formed using low-resistance metals such as aluminum and chromium.

[0057] The protective layer 2f covers the photoelectric conversion unit 2b, control line 2c1, data line 2c2, and bias line 2c3.

[0058] The protective layer 2f may include, for example, at least one of oxide insulating material, nitride insulating material, oxynitride insulating material and resin material.

[0059] like Figure 3 As shown, a plurality of noise detection units 2g are provided. The plurality of noise detection units 2g are arranged outside the region (effective pixel region 201) where a plurality of photoelectric conversion units 2b are provided. The plurality of noise detection units 2g are arranged along at least one of the control line 2c1 and the data line 2c2. For example, as... Figure 3 As shown, multiple noise detection units 2g can be arranged along data line 2c2. For example, multiple noise detection units 2g can be arranged along control line 2c1. For example, multiple noise detection units 2g can be arranged along both control line 2c1 and data line 2c2.

[0060] exist Figure 3 The example shown is that multiple noise detectors 2g are set on one outside of the effective pixel area 201, but they can also be set on two, three, or four outside of the effective pixel area 201.

[0061] Each of the multiple noise detection units 2g includes, for example, a capacitor unit 2g1 and a thin-film transistor 2b2 (an example of a second thin-film transistor). The thin-film transistor 2b2 is electrically connected to a data line 2c2 corresponding to the corresponding control line 2c1. The capacitor unit 2g1 is electrically connected to the thin-film transistor 2b2.

[0062] Alternatively, if the storage capacitor 2b3 is disposed in the photoelectric conversion unit 2b, it can also be disposed in the noise detection unit 2g. For example, the storage capacitor 2b3 can be disposed under the capacitor unit 2g1.

[0063] The capacitor section 2g1 can be formed of a conductive material such as a metal. If the capacitor section 2g1 is formed of a conductive material, even if the fluorescence generated in the scintillator 5 is incident on the capacitor section 2g1, almost no signal charge will be generated. The capacitor section 2g1 can be formed of the same material as the electrode 2b1b of the photoelectric conversion element 2b1. For example, a low-resistance metal such as aluminum or chromium can be used to form the capacitor section 2g1.

[0064] The gate electrode 2b2a of the thin-film transistor 2b2 disposed in the noise detection unit 2g is electrically connected to the corresponding control line 2c1. The drain electrode 2b2b of the thin-film transistor 2b2 is electrically connected to the corresponding data line 2c2. The source electrode 2b2c of the thin-film transistor 2b2 is electrically connected to the corresponding capacitor unit 2g1 and the storage capacitor 2b3.

[0065] Furthermore, details regarding the noise detection unit 2g will be elaborated later.

[0066] The signal processing circuit 3 is located on the side of the array substrate 2 opposite to the scintillator 5.

[0067] like Figure 2 As shown, the signal processing circuit 3 includes, for example, a control circuit 31 and a signal detection circuit 32.

[0068] The control circuit 31 inputs a control signal Sa to thin-film transistors 2b2, which are respectively disposed in multiple photoelectric conversion units 2b and multiple noise detection units 2g. The control circuit 31 switches the on and off states of the thin-film transistors 2b2.

[0069] The control circuit 31 may have, for example, multiple gate drivers 31a and row selection circuit 31b.

[0070] A control signal Sa is input from the image composition circuit 4, the horizontal selection circuit 31b. The horizontal selection circuit 31b inputs the control signal Sa to the corresponding gate driver 31a according to the scanning direction of the X-ray image.

[0071] The gate driver 31a inputs a control signal Sa to the corresponding control line 2c1.

[0072] For example, the control circuit 31 sequentially inputs control signals Sa to each of the control lines 2c1 via the flexible printed circuit board 2e1.

[0073] Using the control signal Sa input to the control line 2c1, the thin film transistor 2b2 installed in the photoelectric conversion unit 2b is turned on, thereby receiving the signal charge (image data signal Sb) from the storage capacitor 2b3.

[0074] The signal detection circuit 32 reads the image data signal Sb from multiple photoelectric conversion units 2b and the noise signal N from multiple noise detection units 2g. For example, when the thin-film transistor 2b2 is in the on state, the signal detection circuit 32 reads the image data signal Sb from the storage capacitor 2b3 via the data line 2c2 and the flexible printed circuit board 2e2 based on the sampling signal from the image forming circuit 4.

[0075] For example, the image data signal Sb can be read in the following manner.

[0076] First, the control circuit 31 sequentially turns on the thin-film transistors 2b2. With the thin-film transistors 2b2 in the on state, a certain amount of charge is stored in the storage capacitor 2b3 via the bias line 2c3. Next, the thin-film transistors 2b2 are turned off. If irradiated with X-rays, the X-rays are converted into fluorescence by the scintillator 5. If the fluorescence is incident on the photoelectric conversion element 2b1, charges (electrons and holes) are generated due to the photoelectric effect. These generated charges combine with the charges (opposite charges) stored in the storage capacitor 2b3, thereby reducing the stored charge. Then, the control circuit 31 sequentially turns the thin-film transistors 2b2 on. The signal detection circuit 32 reads the reduced charge (image data signal Sb) stored in each storage capacitor 2b3 via the data line 2c2 based on the sampling signal.

[0077] Furthermore, when the thin-film transistor 2b2 is in the off state, the signal detection circuit 32 reads the noise current (noise signal N) from the noise detection unit 2g via the data line 2c2 and the flexible printed circuit board 2e2.

[0078] The image composition circuit 4 is electrically connected to the signal detection circuit 32 via wiring 4a. Alternatively, the image composition circuit 4 can be integrated with the signal processing circuit 3, or it can communicate wirelessly with the signal detection circuit 32.

[0079] The image composition circuit 4 constructs an X-ray image based on the read image data signal Sb and the read noise signal N. The constructed X-ray image data is output from the image composition circuit 4 to an external device.

[0080] The scintillator 5 is disposed on a region having multiple photoelectric conversion units 2b, converting incident X-rays into fluorescence. The scintillator 5 is configured to cover the effective pixel region 201 on the substrate 2a. Alternatively, the scintillator 5 may also be configured to cover a region having multiple photoelectric conversion units 2b and multiple noise detection units 2g.

[0081] The scintillator 5 can be formed, for example, using cesium iodide (CsI):thallium (Tl) or sodium iodide (NaI):thallium (Tl). In this case, if the scintillator 5 is formed using a vacuum evaporation method or the like, a scintillator 5 composed of an aggregate of multiple columnar crystals is formed.

[0082] Furthermore, the scintillator 5 can also be formed using, for example, gadolinium oxysulfide (Gd₂O₂S). In this case, a prism-shaped scintillator 5 can be provided for each photoelectric conversion unit 2b.

[0083] In addition, to improve the sensitivity characteristics by increasing the utilization efficiency of fluorescence, a reflective layer (not shown) can be provided to cover the surface side (the incident side of X-rays) of the scintillator 5.

[0084] In addition, in order to suppress the degradation of the properties of the scintillator 5 and the reflective layer (not shown) due to water vapor contained in the air, a moisture-proof body (not shown) covering the scintillator 5 and the reflective layer (not shown) can be provided.

[0085] Next, the noise detection unit 2g will be further explained.

[0086] Noise in X-ray images can be broadly categorized into random noise and transverse noise. Random noise is uniformly distributed across the entire X-ray image, thus lacking a specific pattern or contour. In contrast, transverse noise appears as stripes in the horizontal or vertical direction of the X-ray image. Since X-ray images are what humans see, transverse noise with patterns or contours has a greater impact on X-ray image quality compared to random noise without patterns or contours. Therefore, reducing transverse noise is necessary in X-ray detectors.

[0087] The primary source of lateral noise is considered to be the control circuit 31. For example, noise generated in the control circuit 31 or noise from the power supply lines used to drive the control circuit 31 may sometimes intrude into the control line 2c1. The thin-film transistor 2b2 is electrically connected between the control line 2c1 and the data line 2c2. Therefore, if the thin-film transistor 2b2 is in the off state, noise will not intrude into the data line 2c2 from the control line 2c1. However, the photoelectric conversion element 2b1 is disposed near the thin-film transistor 2b2. Therefore, an inter-line capacitance (parasitic capacitance) is generated between the electrode 2b1b of the photoelectric conversion element 2b1 and the thin-film transistor 2b2, and noise may sometimes intrude into the data line 2c2 from the control line 2c1 via electrostatic coupling. If noise intrudes into the data line 2c2 from the control line 2c1, lateral noise will be generated.

[0088] In this case, reducing the noise generated in the control circuit 31 or the power line can reduce transverse noise. However, if such noise countermeasures are taken, the structure of the X-ray detector 1 becomes more complex, leading to higher costs.

[0089] Therefore, under normal circumstances, multiple noise detection units are set up to detect lateral noise, and the value corresponding to the detected lateral noise is subtracted from the value of the image data signal Sb output by each photoelectric conversion unit 2b, and offset processing is performed.

[0090] Figure 4 and Figure 5 This is a schematic top view used to illustrate the noise detection unit 2g.

[0091] In addition, Figure 4 and Figure 5 In the drawing, the offset line 2c3 is omitted.

[0092] like Figure 4 and Figure 5 As shown, the photoelectric conversion element 2b1 disposed in the photoelectric conversion section 2b includes a semiconductor layer 2b1a having a pn junction or pin structure, and an electrode 2b1b disposed on the substrate 2a side of the semiconductor layer 2b1a. The electrode 2b1b is electrically connected to the source electrode 2b2c of the thin-film transistor 2b2.

[0093] The semiconductor layer 2b1a is not provided in the noise detection unit 2g. For example, the noise detection unit 2g is provided with a capacitor unit 2g1, a thin film transistor 2b2, and a storage capacitor 2b3. Since the semiconductor layer 2b1a is not provided in the noise detection unit 2g, the output from the noise detection unit 2g does not contain a value corresponding to the X-ray dose but contains a value corresponding to the noise.

[0094] Therefore, by subtracting the value of the noise signal N output from the noise detection unit 2g from the value of the image data signal Sb output from each photoelectric conversion unit 2b, an X-ray image with suppressed lateral noise can be obtained. For example, the value used for offset processing can be the average value of the noise signal N output from multiple noise detection units 2g.

[0095] As described above, if an inter-line capacitance is generated between the electrode 2b1b of the photoelectric conversion element 2b1 and the thin-film transistor 2b2, noise will enter the data line 2c2 from the control line 2c1 through electrostatic coupling.

[0096] Therefore, if the inter-line capacitance between capacitor 2g1 and thin-film transistor 2b2 is the same as the inter-line capacitance between electrode 2b1b and thin-film transistor 2b2, the detection accuracy of lateral noise can be improved.

[0097] In order to generate the same level of inter-line capacitance, the dimensions S3 and S4 between the capacitor section 2g1 and the thin-film transistor 2b2 should be the same as the dimensions S1 and S2 between the electrode 2b1b and the thin-film transistor 2b2.

[0098] In other words, the gap size between the thin-film transistor 2b2 and the capacitor 2g1 in the noise detection unit 2g should be approximately equal to the gap size between the thin-film transistor 2b2 and the electrode 2b1b in the photoelectric conversion unit 2b. Furthermore, in this specification, "approximately the same" refers to different permissible manufacturing tolerances.

[0099] In this case, the material of the capacitor 2g1 is preferably the same as the material of the electrode 2b1b.

[0100] The thickness of the capacitor section 2g1 is preferably the same as the thickness of the electrode 2b1b.

[0101] Furthermore, the lengths of the sides 2g1a and 2g1b of the capacitor section 2g1 opposite to the thin-film transistor 2b2 are preferably the same as the lengths of the sides 2b2d and 2b2e of the electrode 2b1b opposite to the thin-film transistor 2b2.

[0102] In recent years, there has been a pursuit of miniaturization of the X-ray detector 1. In this case, since the effective pixel area 201, in which multiple photoelectric conversion units 2b are provided, is the area where X-ray images are captured, it is difficult to make it smaller.

[0103] On the other hand, the area 202 where multiple noise detection units 2g are provided is not the area where X-ray images are taken, so as long as lateral noise can be detected, the noise in this area 202 can be reduced.

[0104] Furthermore, the position of side 2g1c, which is opposite to side 2g1a of capacitor section 2g1, and the position of side 2g1d, which is opposite to side 2g1b, have a relatively small impact on the inter-line capacitance.

[0105] Therefore, as Figure 4 As shown, when multiple noise detection units 2g are arranged along the data line 2c2, the length Lg1 of the capacitor unit 2g1 in the direction orthogonal to the direction in which the data line 2c2 extends can be shorter than the length Lb1 of the electrode 2b1b in the direction orthogonal to the direction in which the data line 2c2 extends.

[0106] In addition, such as Figure 5 As shown, when multiple noise detection units 2g are arranged along the control line 2c1, the length Lg2 of the capacitor unit 2g1 in the direction orthogonal to the direction in which the control line 2c1 extends can be shorter than the length Lb2 of the electrode 2b1b in the direction orthogonal to the direction in which the control line 2c1 extends.

[0107] In addition, as described above, the case of shortening length Lg1 or Lg2 is illustrated, but it is also possible to shorten both length Lg1 and length Lg2.

[0108] In other words, in at least one of the directions in which the control line 2c1 extends and the data line 2c2 extends, the length of the capacitor section 2g1 is shorter than the length of the electrode 2b1b.

[0109] A portion of the electrode 2b1b can also be removed from the capacitor section 2g1. In this way, multiple capacitor sections 2g1 and multiple electrodes 2b1b can be formed through the same process, thereby improving productivity and reducing manufacturing costs.

[0110] Figure 6 (a) Figure 6 (b) is a schematic top view illustrating the configuration of a region 202 in which multiple noise detection units 2g are provided.

[0111] like Figure 6 (a) Figure 6 As shown in (b), the region 202, which is provided with multiple noise detection units 2g, can be located outside the effective pixel region 201.

[0112] For example, Figure 6 (a) is Figure 4 The illustrated case is one where multiple noise detection units 2g are arranged along the data line 2c2. In this case, for example, as... Figure 6 As shown in (a), in the direction in which multiple data lines 2c2 are arranged, a region 202 with multiple noise detection units 2g can be provided on both sides of the effective pixel region 202.

[0113] For example, Figure 6 (b) is Figure 5 The illustrated case is one where multiple noise detection units 2g are arranged along the control line 2c1. In this case, for example, as... Figure 6 As shown in (b), in the direction in which multiple control lines 2c1 are arranged, a region 202 with multiple noise detection units 2g can be provided on both sides of the effective pixel region 201.

[0114] Thus, as Figure 6 As shown in (a), the X-ray detector 1 only enlarges the portion containing region 202. However, as Figure 4 As shown, the length Lg1 of the capacitor section 2g1 in the direction orthogonal to the extension direction of the data line 2c2 is shorter than the length Lb1 of the electrode 2b1b in the direction orthogonal to the extension direction of the data line 2c2. Therefore, the size of the X-ray detector 1 can be suppressed from increasing.

[0115] In addition, such as Figure 6 As shown in (b), the X-ray detector 1 only enlarges the portion containing region 202. However, as Figure 5 As shown, the length Lg2 of the capacitor section 2g1 in the direction orthogonal to the direction in which the control line 2c1 extends is shorter than the length Lb2 of the electrode 2b1b in the direction orthogonal to the direction in which the control line 2c1 extends. Therefore, the size of the X-ray detector 1 can be suppressed from increasing.

[0116] In addition, a region 202 can be set on one side of the effective pixel region 201 in the arrangement direction of multiple data lines 2c2 or in the arrangement direction of multiple control lines 2c1.

[0117] This allows for noise detection and further suppresses the increase in the size of the X-ray detector 1.

[0118] Furthermore, in the direction in which the multiple data lines 2c2 are arranged and in the direction in which the multiple control lines 2c1 are arranged, a region 202 can be set on both sides of the effective pixel region 201. That is, the region 202 can be set to surround the effective pixel region 201. In this case, the size of the X-ray detector 1 can also be suppressed from increasing.

[0119] As described above, region 202 can be set on at least one side outside of effective pixel region 201.

[0120] As described above, the value used for offset processing can be the average value of the noise signal N output from multiple noise detection units 2g. Therefore, increasing the number of noise detection units 2g enables high-precision noise detection, thereby improving the accuracy of removing lateral noise. In this case, increasing the number of regions 202 allows for an increase in the number of noise detection units 2g.

[0121] However, if the number of regions 202 increases, the size of the X-ray detector 1 will increase accordingly. However, as mentioned above, the size of regions 202 can be reduced. Therefore, even if the number of regions 202 increases, the size of the X-ray detector 1 can be prevented from increasing. The number or configuration of regions 202 can be appropriately determined according to the specifications and application of the X-ray detector 1.

[0122] As explained above, the X-ray detector 1 according to this embodiment can detect lateral noise. Furthermore, the area 202 where multiple noise detection units 2g are provided can be reduced. Therefore, noise can be detected, and the size of the X-ray detector 1 can be suppressed from increasing.

[0123] Here, as described above, if the number of noise detection units 2g is increased, noise can be detected with high precision, thereby improving the accuracy of removing transverse noise.

[0124] For example, multiple noise detection units 2g can be electrically connected to multiple data lines 2c2 respectively. For example, multiple noise detection units 2g can be electrically connected to multiple control lines 2c1 respectively. That is, multiple regions 202 can be arranged in a specific configuration. In this way, by increasing the number of noise detection units 2g, noise can be detected with high precision, thereby improving the accuracy of removing lateral noise.

[0125] Figure 7 and Figure 8 This is a schematic top view illustrating the configuration of the noise detection unit 2g according to another embodiment.

[0126] In addition, Figure 7 and Figure 8 In the drawing, the offset line 2c3 is omitted.

[0127] Figure 9 (a) Figure 9 (b) is a schematic top view illustrating the configuration of a region 202 in which multiple noise detection units 2g are provided.

[0128] like Figure 7 As shown, for example, multiple noise detection units 2g can be electrically connected to two adjacent data lines 2c2 respectively. In this case, for example, as... Figure 9 As shown in (a), in the direction in which the multiple data lines 2c2 are arranged, two regions 202 can be provided on both sides of the effective pixel region 201. Alternatively, for example, in the direction in which the multiple data lines 2c2 are arranged, two regions 202 can also be provided on one side of the effective pixel region 201.

[0129] like Figure 8 As shown, for example, multiple noise detection units 2g can be electrically connected to two adjacent control lines 2c1 respectively. In this case, for example, as... Figure 9 As shown in (b), in the direction in which the multiple control lines 2c1 are arranged, two regions 202 can be provided on both sides of the effective pixel region 201. Alternatively, for example, in the direction in which the multiple control lines 2c1 are arranged, two regions 202 can also be provided on one side of the effective pixel region 201.

[0130] Furthermore, in the direction in which the multiple data lines 2c2 are arranged and in the direction in which the multiple control lines 2c1 are arranged, two regions 202 can be set on both sides of the effective pixel region 201. That is, the regions 202 can be set twice to surround the effective pixel region 201.

[0131] Furthermore, although the example shows two regions 202 being provided on at least one side outside the effective pixel region 201, more than three regions 202 can be provided.

[0132] For example, multiple data lines 2c2 can be arranged outside the effective pixel area 201 where multiple photoelectric conversion units 2b are provided, along the direction of the extension of the control line 2c1, and multiple noise detection units 2g can be electrically connected to the multiple data lines 2c2 respectively.

[0133] For example, outside the effective pixel area 201 where multiple photoelectric conversion units 2b are provided, multiple control lines 2c1 can be arranged along the direction of data line 2c2, and multiple noise detection units 2g can be electrically connected to the multiple data lines 2c1 respectively.

[0134] If the number of regions 202 increases, the X-ray detector 1 will correspondingly become larger. However, as mentioned above, the size of regions 202 can be reduced. Therefore, even if the number of regions 202 increases, the size of the X-ray detector 1 can be prevented from increasing. The number or configuration of regions 202 can be appropriately determined according to the specifications and application of the X-ray detector 1.

[0135] Figure 10 and Figure 11 This is a schematic top view illustrating the noise detection unit 2ga according to another embodiment.

[0136] In addition, Figure 10 and Figure 11 In the drawing, the offset line 2c3 is omitted.

[0137] like Figure 10 and Figure 11As shown, the noise detection unit 2ga includes, for example, an electrode 2b1b, a thin-film transistor 2b2, and a storage capacitor 2b3. That is, the noise detection unit 2ga can be obtained by removing the semiconductor layer 2b1a from the photoelectric conversion unit 2b. In this case, the electrode 2b1b provided in the noise detection unit 2ga is equivalent to the capacitor 2g1 provided in the noise detection unit 2g described above.

[0138] Multiple noise detection units 2ga are arranged, for example, outside the effective pixel region 201. Figure 10 As shown, multiple noise detection units 2ga can be arranged along the direction of the data line 2c2. For example... Figure 11 As shown, sometimes multiple noise detection units 2ga can be arranged along the direction of extension of control line 2c1. Alternatively, multiple noise detection units 2ga can be arranged in both the direction of extension of data line 2c2 and the direction of extension of control line 2c1.

[0139] Figure 12 This is a schematic top view illustrating the configuration of a region 202a in which multiple noise detection units 2ga are provided.

[0140] like Figure 12 As shown, the region 202a, which is equipped with multiple noise detection units 2ga, is located outside the effective pixel region 201. Figure 12 In the illustrated case, a region 202a is provided on each side of the effective pixel region 201. Similar to the case of region 202 described above, region 202a can be provided on at least one side outside the effective pixel region 201.

[0141] Similar to the noise detection unit 2g described above, no semiconductor layer 2b1a is provided in the noise detection unit 2ga. Therefore, the output from the noise detection unit 2ga does not contain a value corresponding to the dose of X-rays, but contains a value corresponding to noise.

[0142] Therefore, by subtracting the value of the noise signal N output from the noise detection unit 2ga from the value of the image data signal Sb output from each photoelectric conversion unit 2b, an X-ray image with suppressed lateral noise can be obtained. Furthermore, the value used for offset processing can be the average of the noise signal N values ​​output from the multiple noise detection units 2ga.

[0143] In this case, if the semiconductor layer 2b1a is removed from the photoelectric conversion unit 2b in the noise detection unit 2ga, the dimensions S3a and S4a between the electrode 2b1b and the thin-film transistor 2b2 in the noise detection unit 2ga are approximately the same as the dimensions S1 and S2 between the electrode 2b1b and the thin-film transistor 2b2 in the photoelectric conversion unit 2b. Therefore, the inter-line capacitance in the noise detection unit 2ga is approximately the same as the inter-line capacitance in the photoelectric conversion unit 2b, thus easily improving the detection accuracy of transverse noise.

[0144] On the other hand, considering the miniaturization of the X-ray detector 1, it is preferable to use the noise detection unit 2g described above. Therefore, the type of noise detection unit can be appropriately selected according to the specifications and applications of the X-ray detector 1.

[0145] Here, multiple photoelectric conversion units 2b, multiple control lines 2c1, multiple data lines 2c2, multiple bias lines 2c3, and multiple noise detection units 2g (2ga) are formed on substrate 2a by using semiconductor manufacturing processes such as film deposition by sputtering, photolithography, dry etching, or wet etching.

[0146] In this case, since the structures of the multiple noise detection units 2g (2ga) and the multiple photoelectric conversion units 2b are similar, they can be formed together. However, a semiconductor layer 2b1a is formed in the multiple photoelectric conversion units 2b, but not in the multiple noise detection units 2g (2ga). Therefore, the dry etching and wet etching process conditions are different for the effective pixel region 201 where the multiple photoelectric conversion units 2b are provided and the region 202 (202a) where the multiple noise detection units 2g (2ga) are provided.

[0147] Near the boundary between effective pixel region 201 and region 202 (202a) under different process conditions, the size and other dimensions of the formed elements are prone to change. In this case, if variations in size and other dimensions occur in the photoelectric conversion unit 2b, the image characteristics may change or lines may break, and the quality of the X-ray image may degrade.

[0148] Therefore, the X-ray detector 1 in this embodiment is at least one of (1) to (3) below.

[0149] (1) The signal detection circuit 32 does not read the image data signal Sb from the photoelectric conversion unit 2b adjacent to the noise detection unit 2g (2ga).

[0150] (2) When constructing an X-ray image, the image construction circuit 4 does not use the image data signal Sb read from the photoelectric conversion unit 2b adjacent to the noise detection unit 2g (2ga).

[0151] (3) The photoelectric conversion unit 2b adjacent to the noise detection unit 2g (2ga) is not electrically connected to at least one of the control circuit 31 and the signal detection circuit 32.

[0152] In case (3), for example, the photoelectric conversion unit 2b adjacent to the noise detection unit 2g (2ga) is not electrically connected to at least one of the corresponding control line 2c1 and the corresponding data line 2c2. For example, the electrode or wiring of the thin-film transistor 2b2 disposed in the photoelectric conversion unit 2b adjacent to the noise detection unit 2g (2ga) is disconnected. For example, the data line 2c2 connected to the photoelectric conversion unit 2b adjacent to the noise detection unit 2g (2ga) is disconnected. For example, the data line 2c2 connected to the photoelectric conversion unit 2b adjacent to the noise detection unit 2g (2ga) is not connected to the wiring disposed on the flexible printed circuit board 2e2.

[0153] If at least one of (1) to (3) is selected, the quality of the X-ray image can be maintained even if changes such as size occur in the photoelectric conversion unit 2b formed near the boundary between the effective pixel region 201 and region 202 (202a).

[0154] In addition, the first photoelectric conversion unit 2b adjacent to the noise detection unit 2g (2ga) and the second photoelectric conversion unit 2b sandwiched between the first photoelectric conversion unit 2b and disposed on the opposite side of the noise detection unit 2g (2ga) can be at least one of (1) to (3).

[0155] The above examples illustrate several embodiments of the present invention, but these embodiments are merely illustrative and not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, with various omissions, substitutions, and modifications made without departing from the spirit of the invention. These embodiments and their variations are all included within the scope and spirit of the invention, and also within the scope of the invention as described in the claims and its equivalents. Furthermore, the above embodiments can be implemented in combination with each other.

Claims

1. A radiation detector characterized by, include: Multiple control lines extending along the first direction; Multiple data lines extending along a second direction orthogonal to the first direction; Photoelectric conversion units are respectively arranged in multiple regions divided by the multiple control lines and the multiple data lines; Multiple noise detection units are arranged outside the area where multiple photoelectric conversion units are located; The control signal is input to the control circuit of the first thin-film transistor respectively disposed in the plurality of photoelectric conversion units and the second thin-film transistor respectively disposed in the plurality of noise detection units; A signal detection circuit that reads image data signals from the plurality of photoelectric conversion units and noise signals from the plurality of noise detection units; as well as An image composition circuit for a radiation image is constructed based on the read image data signal and the read noise signal. The radiation detector is at least one of the following three conditions: The signal detection circuit does not read the image data signal from the photoelectric conversion unit adjacent to the noise detection unit; The image forming circuit does not use the image data signal read from the photoelectric conversion unit adjacent to the noise detection unit when forming the radiation image; as well as The photoelectric conversion unit adjacent to the noise detection unit is not electrically connected to at least one of the control circuit and the signal detection circuit.

2. The radiation detector as described in claim 1, characterized in that, Each of the plurality of photoelectric conversion sections has a photoelectric conversion element, which has an electrode electrically connected to the first thin-film transistor. The plurality of noise detection sections each have a capacitor portion electrically connected to the second thin-film transistor. In at least one of the first and second directions, the length of the capacitor portion is shorter than the length of the electrode.

3. The radiation detector as described in claim 2, characterized in that, The gap size between the second thin-film transistor and the capacitor is approximately the same as the gap size between the first thin-film transistor and the electrode.

4. The radiation detector as described in claim 2 or 3, characterized in that, The capacitor portion contains the same material as the electrodes.

5. The radiation detector as described in claim 2 or 3, characterized in that, The plurality of noise detection units are arranged along the data line. The length of the capacitor in the first direction is shorter than the length of the electrode in the first direction.

6. The radiation detector as described in claim 2 or 3, characterized in that, The plurality of noise detection units are arranged along the control line. The length of the capacitor in the second direction is shorter than the length of the electrode in the second direction.

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