Radiation detector with high pixel density

Abstract

Disclosed herein is a radiation detector (100) and a method for operating the radiation detector (100), the method comprising: for i=1, ..., N, during the transfer period (i), while electrically disconnecting the other N-1 pixels of the pixels (1, j), j=1, ..., N of the radiation detector (100) from the first signal processing circuit, the pixel (1, i) of the pixels (1, j), j=1, ..., N is electrically connected to the first signal processing circuit; and for i=1, ..., N, during the transfer period (i), transferring an electrical signal from the pixel (1, i) to the first signal processing circuit.

Description

[Technical field]

[0001] The present disclosure relates to radiation detectors (or image sensors), and more particularly to radiation detectors having a high pixel concentration. [Background technology]

[0002] A radiation detector is a device that measures properties of radiation. Examples of properties may include the spatial distribution of intensity, phase, and polarization of the radiation. Radiation may be radiation that has interacted with an object. For example, the radiation measured by a radiation detector may be radiation that has penetrated an object. Radiation may be electromagnetic radiation, such as infrared light, visible light, ultraviolet light, X-rays, or gamma rays. Radiation may also be other types, such as alpha rays and beta rays. Radiation may include radiation particles, such as photons (electromagnetic waves) and subatomic particles.

[0003] The quality of an image captured by a radiation detector (or image sensor) depends on the number of pixels in the radiation detector. The greater the number of pixels, the better the image quality. It is always desirable to increase the pixel concentration (the number of pixels per unit area) of a radiation detector in order to improve the resolution (and therefore the quality) of the image captured by the radiation detector. [Summary of the invention]

[0004] A radiation detector is disclosed herein, which includes a first detector part, which includes: pixels (1, j), j=1,..., N, where N is an integer greater than 1; a first switching device, electrically connected to the pixels (1, j), j=1,..., N; and a first signal processing circuit, electrically connected to the first switching device, wherein, for i=1,..., N, during a transfer period (i), the first switching device is configured to (a) electrically connect the pixel (1, i) to the first signal processing circuit and (b) electrically disconnect the other N-1 pixels among the pixels (1, j), j=1,..., N from the first signal processing circuit.

[0005] According to an embodiment, N=4.

[0006] According to an embodiment, the radiation detector also includes a second detector part, which includes: pixels (2, j), j=1,..., N; a second switching device, electrically connected to the pixels (2, j), j=1,..., N; and a second signal processing circuit, electrically connected to the second switching device, wherein, for i=1,..., N, during the transfer period (i), the second switching device is configured to (a) electrically connect the pixel (2, i) to the second signal processing circuit and (b) electrically disconnect the other N-1 pixels among the pixels (2, j), j=1,..., N from the second signal processing circuit.

[0007] According to an embodiment, the first detector portion further comprises solder balls, and the first switching device is electrically connected to the first signal processing circuit via the solder balls.

[0008] According to an embodiment, the first processing circuit comprises an analog-to-digital converter.

[0009] According to an embodiment, the first switching device includes a transfer electrical switch (i), i=1,...,N, and for i=1,...,N, the transfer electrical switch (i) is configured to electrically connect the pixel (1,i) to the first signal processing circuit when it is turned on.

[0010] According to an embodiment, each of the transfer electrical switches (i), i=1, ..., N comprises a transistor.

[0011] According to an embodiment, for i=1, ..., N, during a non-transfer and non-accumulation period (i) immediately preceding the transfer period (i), the first switching device is configured to (a) electrically ground the pixel (1, i), and (b) electrically disconnect the pixel (1, i) from the first signal processing circuit.

[0012] According to an embodiment, the first switching device comprises a grounding electrical switch (i), i=1, ..., N, and for i=1, ..., N, the grounding electrical switch (i) is configured to electrically ground the pixel (1, i) when turned on.

[0013] According to an embodiment, the radiation detector further comprises a shutter configured to expose the pixels (1, j), j=1, ..., N to incident radiation during an open shutter time window prior to the transfer period (i), i=1, ..., N.

[0014] A method for operating a radiation detector is disclosed herein, the method comprising: for i=1, ..., N, during the transfer period (i), while electrically disconnecting the other N-1 pixels among the pixels (1, j), j=1, ..., N of the radiation detector from the first signal processing circuit, the pixel (1, i) among the pixels (1, j), j=1, ..., N is electrically connected to the first signal processing circuit; and for i=1, ..., N, during the transfer period (i), transferring the electrical signal from the pixel (1, i) to the first signal processing circuit.

[0015] According to an embodiment, the method also includes: for i=1,...,N, during the transfer period (i), while electrically disconnecting the other N-1 pixels among the pixels (2,j),j=1,...,N of the radiation detector from the second signal processing circuit, the pixel (2,i) among the pixels (2,j),j=1,...,N is electrically connected to the second signal processing circuit; and for i=1,...,N, during the transfer period (i), the electrical signal is transferred from the pixel (2,i) to the second signal processing circuit.

[0016] According to an embodiment, the electrical connection while being electrically disconnected and the transfer for i=1, . . . , N are performed K times in a cyclic manner, K being an integer greater than 1.

[0017] According to an embodiment, the first processing circuit comprises an analog-to-digital converter.

[0018] According to an embodiment, the method further includes: opening a shutter of the radiation detector during an open shutter time window before the transfer period (i), i=1, ..., N; and exposing the pixel (1, j), j=1, ..., N to incident radiation through the shutter during the open shutter time window.

[0019] According to an embodiment, the method also includes using an electronic system of the radiation detector to process (a) electrical signals from pixels (1, j), j=1, ..., N, and (b) other electrical signals from other pixels of the radiation detector to form an image of the scene.

[0020] According to an embodiment, the radiation detector includes a first switching device, and for i=1, ..., N, during the transfer period (i), the electrical connection while being electrically disconnected includes using the first switching device to electrically connect the pixel (1, i) to the first signal processing circuit while causing the first switching device not to electrically connect the other N-1 pixels among the pixels (1, j), j=1, ..., N to the first signal processing circuit.

[0021] According to an embodiment, the first signal processing circuit is electrically connected to the first switching device via solder balls.

[0022] According to an embodiment, (a) the first switching device includes a transfer electrical switch (j), j=1,...,N, (b) for i=1,...,N, the transfer electrical switch (i) is configured to electrically connect the pixel (1,i) to the first signal processing circuit when turned on, and (c) for i=1,...,N, the use of the first switching device during the transfer cycle (i) includes: during the transfer cycle (i), while turning on the transfer electrical switch (i), while turning off the other N-1 transfer electrical switches among the transfer electrical switch (j), j=1,...,N.

[0023] According to an embodiment, the method further includes, for i=1, ..., N, during a non-accumulation non-transfer period (i) immediately preceding the transfer period (i), using the first switching device to (a) electrically ground the pixel (1, i), and (b) electrically disconnect the pixel (1, i) from the first signal processing circuit.

[0024] According to an embodiment, the first switching device includes a grounding electrical switch (i), i=1,...,N, and for i=1,...,N, the use of the first switching device during the non-accumulation non-transfer period (i) includes turning on the grounding electrical switch (i) during the non-accumulation non-transfer period (i) to electrically ground the pixel (1,i).

Brief Description of the Drawings

[0025] Figure 1 A top view of a radiation detector according to an embodiment is schematically shown.

[0026] Figure 2A Schematically shows a Figure 1 A simplified cross-sectional view of a radiation detector.

[0027] Figure 2B Schematically shows Figure 2AAn embodiment of a radiation detector.

[0028] Figure 2C Schematically shows a Figure 2B A top view of a radiation detector.

[0029] Figure 3 Schematically shows a Figure 2B The detector portion of the radiation detector.

[0030] Figure 4A , 4B 4C show timing diagrams illustrating the operation of a radiation detector according to various embodiments. [Specific implementation method]

[0031] Figure 1 The top view of the radiation detector 100 in the embodiment is schematically shown. Specifically, the radiation detector 100 may include an array of pixels 150. The array may be a rectangular array (eg Figure 1 as shown), a honeycomb array, a hexagonal array, or any other suitable array. Figure 1 The radiation detector 100 of illustrative embodiments includes 24 pixels 150 arranged in a rectangular array of 4 rows and 6 columns; however, in general, the radiation detector 100 may have any number of pixels 150 arranged in any manner.

[0032] Each pixel 150 can be configured to detect radiation incident thereon from a radiation source, and can be configured to measure characteristics of the radiation (e.g., energy, wavelength, and frequency of the particles). For example, each pixel 150 can be configured to count the number of radiation particles whose energy falls within a plurality of energy intervals incident thereon over a period of time. All pixels 150 can be configured to count the number of radiation particles incident thereon within a plurality of energy intervals over the same period of time.

[0033] Each pixel 150 may have its own analog-to-digital converter (ADC) configured to digitize an analog signal representing the energy of an incident radiation particle into a digital signal, or digitize an analog signal representing the energy of an incident radiation particle into a digital signal. The pixels 150 may be configured to operate in parallel. For example, when one pixel 150 measures an incident radiation particle, another pixel 150 may be waiting for the radiation particle to arrive. The pixels 150 may not necessarily be individually addressable.

[0034] The radiation detector 100 described herein may be applied, for example, in X-ray telescopes, X-ray mammography, industrial X-ray defect detection, X-ray microscopy or microradiography, X-ray casting inspection, X-ray nondestructive testing, X-ray weld inspection, X-ray digital subtraction angiography, etc. It may be appropriate to use the radiation detector 100 instead of a photographic plate, photographic film, PSP board, X-ray image intensifier, scintillator or other semiconductor X-ray detector. The radiation detector 100 may also be used as an image sensor that captures an image of an object or scene by detecting visible light photons.

[0035] Figure 2A Schematically shows a Figure 1 2A-2A of a simplified cross-sectional view of a radiation detector 100. Specifically, the radiation detector 100 may include a radiation absorbing layer 110 and an electronic device layer 120 (e.g., an ASIC) for processing or analyzing an electrical signal generated in the radiation absorbing layer 110 by incident radiation. The radiation detector 100 may or may not include a scintillator (not shown). The radiation absorbing layer 110 may include a semiconductor material, such as silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof. The semiconductor material may have a high mass attenuation coefficient for the radiation of interest.

[0036] Figure 2B The embodiment of the present invention is schematically shown. Figure 2A Detailed view of radiation detector 100 of FIG. 1 . It should be noted that in this figure and subsequent figures, some components have reference numerals with extensions. These extensions are added simply to facilitate identification of these components. For example, pixel 150.1 is just like other pixels 150. The extension ".1" is added to "150" just to facilitate identification of that particular pixel 150.1. As a result, "pixel 150" refers to all pixels 150 including pixel 150.1; but "pixel 150.1" refers only to that pixel 150.1 and not to any other pixel 150.

[0037] In an embodiment, the radiation absorbing layer 110 may include one or more diodes (e.g., pin or pn junctions) formed by one or more discrete regions 114 of the first doped region 111 and the second doped region 113. The second doped region 113 may be separated from the first doped region 111 by an optional intrinsic region 112. The discrete portions 114 are separated from each other by the first doped region 111 or the intrinsic region 112. The first doped region 111 and the second doped region 113 have opposite types of doping (e.g., region 111 may be p-type and region 113 may be n-type, or region 111 may be n-type and region 113 may be p-type).

[0038] In an embodiment, each discrete region 114 of the second doped region 113 forms a diode with the first doped region 111 and the optional intrinsic region 112. Figure 2B , the radiation absorbing layer 110 has a plurality of diodes corresponding to the same number of pixels 150. More specifically, although in Figure 2B Only six diodes corresponding to six pixels 150 are shown, but there are a total of Figure 1 24 diodes of 24 pixels 150. The plurality of diodes may have an electrode 119A as a common electrode, which may include polysilicon. The first doped region 111 may also have discrete portions.

[0039] In an embodiment, the electronics layer 120 may include an electronic system suitable for processing or interpreting the electrical signals (i.e., charge carriers) generated in the pixels 150 by radiation incident on the radiation absorbing layer 110. The electronic system may include analog circuits such as filter networks, amplifiers, integrators, and comparators, or digital circuits such as microprocessors and memories. The electronic system may include one or more ADCs.

[0040] The electronic system may include (a) components each shared by all pixels 150 and (b) components each dedicated to a group of pixels 150 (a group of pixels 150 may include one or more pixels 150, but not all pixels 150). For example, the electronic system may include a microprocessor shared among all pixels 150. For another example, the electronic system may include signal processing circuits 121, each signal processing circuit 121 being dedicated to a group of pixels 150. Each signal processing circuit 121 may include an analog-to-digital converter dedicated to a group of pixels 150.

[0041] When radiation from a radiation source (not shown) strikes the radiation absorbing layer 110, the radiation photons may be absorbed and generate one or more charge carriers (e.g., electrons, holes) by a variety of mechanisms. The charge carriers may drift to an electrode of one of the diodes / pixels 150 under an electric field. The electric field may be an external electric field. The electrical contact 119B may include a discrete portion that is in electrical contact with the discrete region 114. The term "electrical contact" may be used interchangeably with the word "electrode".

[0042] In embodiments, charge carriers may drift in directions such that charge carriers generated by a single radiation particle are not substantially shared by two different discrete regions 114 (where “substantially not shared by” means that less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these charge carriers flow toward one different discrete region 114 compared to the rest of the charge carriers). Charge carriers generated by radiation particles incident around the footprint of one of the discrete regions 114 are not substantially shared with another of the discrete regions 114. A pixel 150 associated with a discrete region 114 may be an area around the discrete region 114 in which substantially all (greater than 98%, greater than 99.5%, greater than 99.9%, or greater than 99.99%) of the charge carriers generated by radiation particles incident therein flow toward the discrete region 114. That is, less than 2%, less than 1%, less than 0.1%, or less than 0.01% of these charge carriers flow through the pixel 150.

[0043] In an embodiment, radiation detector 100 may further include (a) solder ball layer 130 including solder balls 132, and (b) switching layer 140 including switching regions 142. Switching regions 142 electrically connect pixels 150 to signal processing circuitry 121 via electrodes 119B and solder balls 132 during some transfer operations / cycles.

[0044] Figure 2C The embodiment of the present invention is schematically shown. Figure 2B FIG. 1 is a top view of a radiation detector 100. For simplicity, Figure 2C Only the pixel 150, solder ball 132 and switch region 142 of the radiation detector 100 are shown (other components of the radiation detector 100, such as the signal processing circuit 121 and the electrode 119B, are not shown). It should be noted that Figure 2B yes Figure 2C A cross-sectional view of radiation detector 100 taken along line 2B-2B.

[0045] Reference Figure 2B and Figure 2CIn an embodiment, the 24 pixels 150 of the radiation detector 100 can be divided into 6 groups of 4 pixels 150. Each group can be connected to the signal processing circuit 121 via the switch area 142 and the solder ball 132. For example, a group of 4 pixels 150.1, 150.2, 150.3 and 150.4 (or simply 150.1-4) can be connected to the signal processing circuit 121.1 via the switch area 142.1 and the solder ball 132.1. As a result, the radiation detector 100 includes, among other things, a total of 24 pixels 150, 24 electrodes 119B, 6 switch areas 142, 6 solder balls 132, and 6 signal processing circuits 121. In an embodiment, each solder ball 132 may include a conductive material, such as a combination of lead (Pb) and tin (Sn).

[0046] In an embodiment, Figure 2B The radiation detector 100 may be formed as follows. First, a first substrate including a top portion of the radiation detector 100 and a second substrate including a bottom portion of the radiation detector 100 may be formed separately. Specifically, the first substrate may include a switch layer 140 and other layers above the switch layer 140, and the second substrate may include an electronic device layer 120.

[0047] Next, solder balls 132 may be formed on the top surface of the electronic device layer 120 of the second substrate so that the solder balls 132 are electrically connected to the signal processing circuit 121. Next, the first substrate and the second substrate may be bonded together at high temperature so that the solder balls 132 are electrically connected to the switch regions 142 on the first substrate. Any void space around the solder balls 132 after bonding may be filled with a dielectric material, thereby obtaining the solder ball layer 130 and also obtaining Figure 2B A radiation detector 100 is provided.

[0048] Reference Figure 2B and Figure 2C , the radiation detector 100 can be divided into six detector sections, each detector section including a group of four pixels 150 , and associated switching regions 142 , solder balls 132 , and signal processing circuits 121 . Figure 3 1 shows one of the six detector sections (i.e., detector section 300) according to an embodiment. The other five detector sections are similar in structure and operation to detector section 300. Specifically, detector section 300 includes four pixels 150.1-4, and their associated switching regions 142.1, solder balls 132.1, and signal processing circuits 121.1.

[0049] In an embodiment, the switch area 142.1 may include eight electrical switches Sa1, Sb1, Sa2, Sb2, Sa3, Sb3, Sa4, and Sb4. The electrical switches Sa1, Sa2, Sa3, and Sa4 electrically connect the electrodes 119B.1, 119B.2, 119B.3, and 119B.4 of the pixels 150.1, 150.2, 150.3, and 150.4 to the signal processing circuit 121.1 via the solder balls 132.1 when turned on. The electrical switches Sb1, Sb2, Sb3, and Sb4 ground the electrodes 119B.1, 119B.2, 119B.3, and 119B.4 of the pixels 150.1, 150.2, 150.3, and 150.4, respectively, when turned on. In an embodiment, each of the eight electrical switches Sa1, Sb1, Sa2, Sb2, Sa3, Sb3, Sa4, and Sb4 may be implemented using a junction field effect transistor (JFET).

[0050] Figure 4A A first timing diagram is schematically shown, which illustrates a timing diagram according to an embodiment of the present invention. Figure 3 The operation of the detector portion 300 according to the first timing diagram may be as follows.

[0051] Assume that the radiation detector 100 is exposed to incident radiation 205 ( Figure 2B ). Then, at time t=0, the radiation detector 100 is turned on.

[0052] With respect to pixel 150.1, during an accumulation period (or accumulation operation) A11, electrical switches Sa1 and Sb1 are turned off, with the result that charge carriers generated in pixel 150.1 are accumulated in pixel 150.1. Then, during a transfer period (or transfer operation) T11, electrical switch Sa1 is turned on and electrical switch Sb1 is turned off. As a result, charge carriers accumulated in pixel 150.1 during accumulation period A11 and during transfer period T11 are transferred via electrical switch Sa1 to solder ball 132.1, and then to signal processing circuit 121.1 and other components of electronic device layer 120 for processing. At the end of transfer period / operation T11, there are no charge carriers in pixel 150.1 (because transfer operation T11 depletes all charge carriers in pixel 150.1).

[0053] The other accumulation operations (A12, A13 and others thereafter) for pixel 150.1 are similar to accumulation operation A11. The other transfer operations (T12 and others thereafter) for pixel 150.1 are similar to transfer operation T11. The accumulation operations and transfer operations for the other pixels 150.2-4 of detector portion 300 are similar to the accumulation operations and transfer operations for pixel 150.1.

[0054] In an embodiment, by Figure 4A It can be seen that the transfer operation of pixels 150.1-4 is performed sequentially in a cyclic manner. Specifically, the transfer operation is performed on pixel 150.1 (T11), then on pixel 150.2 (T21), then on pixel 150.3 (T31), then on pixel 150.4 (T41), then on pixel 150.1 again (T12), then on pixel 150.2 again (T22), then on pixel 150.3 again (T32), then on pixel 150.4 again (T42), and so on.

[0055] It should be noted that when a transfer operation is performed on a pixel among the four pixels 150.1-4 of the detector portion 300, the switch area 142.1 electrically connects only the pixel to the signal processing circuit 121.1, while the switch area 142.1 electrically disconnects the other three pixels of the pixels 150.1-4 from the signal processing circuit 121.1 (i.e., the switch area 142.1 does not electrically connect the other three pixels of the pixels 150.1-4 to the signal processing circuit 121.1). It should also be noted that during the operation of the detector portion 300 according to the first timing diagram, the four electrical switches Sb1, Sb2, Sb3 and Sb4 are always in the off state, so if the radiation detector 100 is to be operated according to the first timing diagram, these switches can be omitted.

[0056] In an embodiment, except for the first period (A11, A21, A31, and A41), the duration of all accumulation operations is the same, and the duration of all transfer operations is the same. For example, the duration of accumulation operations A12 and A22 is the same. For another example, the duration of accumulation operations T12 and T22 is the same. These conditions ensure that for any transfer operation on any pixel, the pixel has the same radiation exposure time.

[0057] In an embodiment, six transfer operations may be performed simultaneously on six pixels 150 on six detector sections of the radiation detector 100 at a time (basically, the relative timing of the operations of the six detector sections does not have to be synchronized). Specifically, assume that the second, third, fourth, fifth, and sixth detector sections of the radiation detector include pixels 150.5-8, 150.9-12, 150.13-16, 150.17-20, and 150.21-24, respectively. Then, for i=1, ..., 4, the transfer operations on pixels 150.i, 150.(i+4), 150.(i+8), 150.(i+12), 150.(i+16), and 150.(i+20) may be performed simultaneously. For example, for i=1, six transfer operations on pixels 150.1, 150.5, 150.9, 150.13, 150.17, and 150.21 may be performed simultaneously. In other words, whenever a transfer operation is performed on pixel 150.1, the other five transfer operations on pixels 150.5, 150.9, 150.13, 150.17, and 150.21 may also be performed at the same time as the transfer operation on pixel 150.1. In an embodiment, the operations of the other five detector sections of radiation detector 100 may be similar to the operation of detector section 300.

[0058] In an embodiment, after each round of 24 transfer operations for 24 pixels of the radiation detector 100, the electronics layer 120 and the computer may process the electrical signals from the 24 transfer operations to form images of 24 corresponding regions on the object (or scene) 210. For example, in the first timing diagram, an image forming operation may be performed after transfer operation T42, thereby processing electrical signals from 24 transfer operations (including T12, T22, T32, and T42 of the detector portion 300) to form images of 24 corresponding regions on the object (or scene) 210. In an embodiment, an image obtained from a previous image forming operation performed after transfer operation T41 may be ignored because the durations of the 24 previous accumulation cycles (including A11, A21, A31, and A41 of the detector portion 300) are different.

[0059] Figure 4B A second timing diagram is schematically shown, which illustrates a timing diagram according to an alternative embodiment. Figure 3 The operation of the detector portion 300 of FIG. 1 is shown (and the operation of the other five detector portions of the radiation detector 100 is also shown). It should be noted that if Figure 4A Each accumulation cycle (e.g., A11, A12, etc.) of the first timing diagram is changed to a non-transfer non-accumulation cycle, and the result is Figure 4B The second timing diagram.

[0060] In the embodiment, according to Figure 4BThe operation of the radiation detector 100 of the second timing diagram may be similar to that according to Figure 4A The operation of the radiation detector 100 of the first timing diagram is shown. For a similar example, the transfer operation of the pixels 150 of each detector portion (e.g., the detector portion 300) according to the second timing diagram is also performed in a cyclic manner. For another similar example, during the transfer operation on the pixel 150, the associated switch Sa is turned on and the associated switch Sb is turned off (e.g., during the transfer operation on the pixel 150.1, the switch Sa1 is turned on and the switch Sb is turned off). For yet another similar example, an image forming operation may be performed after each round of 24 transfer operations on the 24 pixels 150 of the radiation detector 100 (e.g., the image forming operation may be performed after the transfer operation T42 in the second timing diagram).

[0061] In an embodiment, a similar exception is that during the non-transfer, non-accumulation period of a pixel 150 of the radiation detector 100, the pixel is electrically grounded and electrically disconnected from the associated solder ball and the associated signal processing circuit (its associated switch Sa is open, and its associated switch Sb is on). For example, during the non-transfer, non-accumulation period of pixel 150.1, switch Sa1 is open and switch Sb1 is on. As a result, pixel 150.1 is electrically grounded and electrically disconnected from solder ball 132.1 and the associated signal processing circuit 121.1. This means that during these non-transfer, non-accumulation periods of pixel 150, all charge carriers generated in the pixel are immediately drained to ground.

[0062] Figure 4C A third timing diagram is schematically shown, which illustrates a timing diagram according to yet another alternative embodiment. Figure 3 The operation of the detector portion 300 of the radiation detector 100 is also illustrated. It should be noted that the third timing diagram is Figure 4A The first timing diagram of FIG. 1 is added with the same open shutter time window (S1, S2, S3, etc.) applied thereto just before each round of 4 transfer operations for pixels 150.1-4 but after the previous round of 4 transfer operations (if any). For example, the open shutter time window S2 is before the second round of 4 transfer operations T12, T22, T32, and T42 for pixels 150.1-4, but after the first round of 4 transfer operations T11, T21, T31, and T41.

[0063] In an embodiment, the radiation detector 100 may include a shutter (not shown) that is opened only during an open shutter time window so as to expose 24 pixels 150 to the incident radiation 205 (i.e., the pixels 150 are not exposed to the incident radiation 205 outside these open shutter time windows). As a result, the accumulation period in the first timing diagram becomes a preparation accumulation period in the third timing diagram. In the third timing diagram, only part of the preparation accumulation period within the open shutter time window is an accumulation period. For example, in the third timing diagram, part of the preparation accumulation period A11 within the open shutter time window S1 is an accumulation period / operation during which charge carriers (electrical signals) are generated and accumulated in the pixel 150.1 due to the incident radiation 205.

[0064] In an embodiment, in addition to the presence of a shutter that exposes the 24 pixels 150 of the radiation detector 100 to the incident radiation 205 only during the open shutter time windows S1, S2, S3, etc., according to Figure 4C The operation of the radiation detector 100 of the third timing diagram is similar to that according to Figure 4A A first timing diagram illustrates the operation of the radiation detector 100 .

[0065] The 24 pixels 150 of the radiation detector 100 are divided into 6 groups, each group of 4 pixels 150. The 4 pixels 150 in each group share some components, such as the signal processing circuit 121. Therefore, each signal processing circuit 121 receives electrical signals from the 4 pixels 150 of the associated pixel group in sequence (i.e., sequentially) via the associated solder balls 132 and with the help of the electrical switches of the associated switching area 142. In other words, during the transfer operation of these 4 pixels 150, the electrical switches of the associated switching area 142 electrically connect the 4 pixels 150 of the associated pixel group in sequence (i.e., sequentially) to the associated signal processing circuit 121.

[0066] Thus, the pixel 150 may have a smaller footprint than the signal processing circuit 121. As shown in the examples herein, each signal processing circuit 121 is shared by four pixels 150 (e.g., Figure 3 , the signal processing circuit 121.1 is shared by four pixels 150.1-4). As a result, the number of pixels 150 can be four times the number of signal processing circuits 121. In other words, the radiation detector 100 of the present disclosure achieves a higher pixel density.

[0067] In the above-described embodiments, solder balls 132 are used to form the radiation detector 100 from two separate first and second substrates. In alternative embodiments, the first and second substrates may be bonded together by direct bonding (i.e., without the use of solder balls 132). In yet another alternative embodiment, only one substrate is used in the formation of the radiation detector 100. As a result, solder balls 132 are not required. Specifically, in these alternative embodiments, reference is made to Figure 2B , the switch region 142 can directly connect the electrode 119B of the pixel 150 to the signal processing circuit 121 without the need for the solder ball 132 (and therefore without the solder ball layer 130). Figure 3 , electrical switches Sa1, Sb1, Sa2, Sb2, Sa3, Sb3, Sa4 and Sb4 connect electrodes 119B.1-4 directly to signal processing circuit 121.1 without solder balls 132.1. In embodiments, the operation of radiation detector 100 in these alternative embodiments is similar to the operation in the embodiment where solder balls 132 are present.

[0068] In the above embodiment, the radiation detector 110 includes 24 pixels 150, which are divided into 6 groups of 4 pixels each. In general, the radiation detector 110 may include any number of pixels 150, which may be divided into groups containing any number of pixels 150. For example, the radiation detector 110 may include 36 pixels 150, which are divided into 4 groups of 9 pixels each. As a result, there are 4 detector sections, each of which includes 9 pixels 150, a switch region 142, solder balls 132, and signal processing circuits 121. In this case, each switch region 142 includes (a) 9 Sa switches, which, when turned on, electrically connect the 9 pixels 150 of the associated detector section to the associated solder balls; and (b) 9 Sb switches, which, when turned on, electrically ground the 9 pixels 150 of the associated detector section. According to the above description, each switch area 142 operates as a switch device, and thus may also be referred to as a switch device 142 .

[0069] In the above-described embodiment, three timing diagrams (i.e., the first timing diagram, the second timing diagram, and the third timing diagram) for the operation of the radiation detector 100 are described. In an embodiment, there may be a fourth timing diagram (not shown) for the operation of the radiation detector 100. Specifically, if Figure 4A Each accumulation cycle (e.g., A11, A12, etc.) of the first timing diagram is completely changed to a non-transfer non-accumulation cycle, and the result is as described above. Figure 4B Or, if only Figure 4AIf a portion (of the same duration) of each accumulation period (eg, A11, A12, etc.) of the first timing diagram is changed to a non-transfer non-accumulation period, the result is a fourth timing diagram.

[0070] Although various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and not limitation, with the true scope and spirit being indicated by the appended claims.

Claims

1. A radiation detector, include: A first detector portion, the first detector portion comprising: Pixel (1, j), j = 1, ..., N, where N is an integer greater than 1; a first switching device electrically connected to said pixel (1, j), j=1, ..., N; and a first signal processing circuit, electrically connected to the first switching device, wherein, for i=1, ..., N, during a transfer period (i), the first switching device is configured to (a) electrically connect the pixel (1, i) to the first signal processing circuit and (b) electrically disconnect the other N-1 pixels of the pixel (1, j), j=1, ..., N from the first signal processing circuit; A second detector portion, said second detector portion comprising: pixel (2, j), j = 1, ..., N, a second switching device electrically connected to said pixel (2, j), j=1, ..., N; and a second signal processing circuit, electrically connected to the second switching device, Wherein, for i=1, ..., N, during the transfer period (i), the second switching device is configured to (a) electrically connect the pixel (2, i) to the second signal processing circuit and (b) electrically disconnect the other N-1 pixels among the pixels (2, j), j=1, ..., N from the second signal processing circuit.

2. The radiation detector according to claim 1, in, N＝4。 3. The radiation detector according to claim 1, in, The first detector portion further includes solder balls, and Wherein, the first switch device is electrically connected to the first signal processing circuit via the solder ball.

4. The radiation detector according to claim 1, in, The first signal processing circuit includes an analog-to-digital converter.

5. The radiation detector according to claim 1, in, The first switch device comprises a transfer switch (i), i=1, ..., N, and Wherein, for i=1, ..., N, the transfer switch (i) is configured to electrically connect the pixel (1, i) to the first signal processing circuit when it is turned on.

6. The radiation detector according to claim 5, in, Each of the transfer electrical switches (i), i=1, ..., N, comprises a transistor.

7. The radiation detector according to claim 1, in, For i=1, ..., N, during a non-transfer and non-accumulation period (i) immediately preceding the transfer period (i), the first switching device is configured to (a) electrically ground the pixel (1, i), and (b) electrically disconnect the pixel (1, i) from the first signal processing circuit.

8. The radiation detector according to claim 7, in, The first switch device comprises a grounding electrical switch (i), i=1, ..., N, and Wherein, for i=1, ..., N, the grounding switch (i) is configured to electrically ground the pixel (1, i) when it is turned on.

9. The radiation detector of claim 1, further comprising a shutter configured to expose the pixels (1, j), j=1, ..., N to incident radiation during an open shutter time window prior to the transfer period (i), i=1, ..., N.

10. A method of operating a radiation detector, include: for i=1, ..., N, during a transfer period (i), electrically connecting the pixel (1, i) of the pixel (1, j), j=1, ..., N of the radiation detector to the first signal processing circuit while electrically disconnecting the other N-1 pixels of the pixel (1, j), j=1, ..., N from the first signal processing circuit; For i=1, ..., N, during the transfer period (i), transferring the electrical signal from the pixel (1, i) to the first signal processing circuit; for i=1, ..., N, during the transfer period (i), the pixel (2, j), j=1, ..., N of the radiation detector is electrically connected to the second signal processing circuit while the other N-1 pixels are electrically disconnected from the second signal processing circuit; as well as For i=1, ..., N, during the transfer period (i), the electrical signal is transferred from the pixel (2, i) to the second signal processing circuit.

11. The method according to claim 10, in, The electrical connection while being electrically disconnected and the transfer for i=1, . . . , N are performed K times in a cyclic manner, K being an integer greater than 1.

12. The method according to claim 10, in, The first signal processing circuit includes an analog-to-digital converter.

13. The method according to claim 10, further comprising: include: opening a shutter of the radiation detector during an open shutter time window before the transfer period (i), i=1, ..., N; as well as During the open shutter time window, the pixels (1, j), j=1, ..., N are exposed to incident radiation through the shutter.

14. The method according to claim 10 also includes using the electronic system of the radiation detector to process (a) the electrical signal from the pixel (1, j), j=1,...,N, and (b) other electrical signals from other pixels of the radiation detector to form an image of the scene.

15. The method according to claim 10, in, The radiation detector comprises a first switching device, and Wherein, for i=1, ..., N, during the transfer period (i), the electrical connection while being electrically disconnected includes using the first switching device to electrically connect the pixel (1, i) to the first signal processing circuit while causing the first switching device not to electrically connect the other N-1 pixels among the pixels (1, j), j=1, ..., N to the first signal processing circuit.

16. The method according to claim 15, in, The first signal processing circuit is electrically connected to the first switching device via solder balls.

17. The method according to claim 15, in, The first switch device comprises a transfer switch (j), j=1, ..., N, wherein, for i=1, ..., N, the transfer switch (i) is configured to electrically connect the pixel (1, i) to the first signal processing circuit when it is turned on, and Wherein, for i=1, ..., N, the use of the first switching device during the transfer cycle (i) includes: during the transfer cycle (i), while turning on the transfer power switch (i) and the other N-1 transfer power switches in j=1, ..., N, are turned off.

18. The method according to claim 15 further includes, for i=1,...,N, during a non-accumulation non-transfer period (i) immediately preceding the transfer period (i), using the first switching device to (a) electrically ground the pixel (1, i) and (b) electrically disconnect the pixel (1, i) from the first signal processing circuit.

19. The method according to claim 18, in, The first switch device comprises a grounding electrical switch (i), i=1, ..., N, and Wherein, for i=1, ..., N, the use of the first switching device during the non-accumulation non-transfer period (i) includes turning on the grounding switch (i) during the non-accumulation non-transfer period (i) to electrically ground the pixel (1, i).

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