Image sensor

Abstract

Disclosed herein is an image sensor (9000) comprising: a plurality of partial images (1010, 1020) movable in a first direction (951) between a plurality of positions (910, 920) relative to a scene (50) and respectively taking a plurality of partial images (1010, 1020) of the scene (50) at the plurality of positions (910, 920); the image sensor (9000) has an active area (190) and a dead area (195); wherein the dead zone (195) extends in a second direction (952), the second direction (952) being non-parallel to the first direction (951).

Description

[0001] This application is a divisional application of Chinese Patent Application No. 202080096372.2, which was filed on November 25, 2020, and is entitled "Imaging Method". Technical Field

[0002] This application relates to imaging technology, and more particularly to image sensors. Background Technology

[0003] A radiation detector can be a device used to measure the flux, spatial distribution, spectrum, or other properties of radiation.

[0004] Radiation detectors have applications in many fields. One important application is imaging. Radiation imaging is a radiographic technique that can be used to reveal the internal structure of opaque objects with non-uniform compositions, such as the human body.

[0005] Early radiation detectors used for imaging included photographic plates and photographic film. The photographic plate could be a glass plate with a photosensitive emulsion coating. Although photographic plates were replaced by photographic film, they are still used in special cases due to their superior quality and extreme stability. Photographic film could be a plastic film (e.g., a strip or sheet) with a photosensitive emulsion coating.

[0006] In the 1980s, photoexcited phosphor plates (PSP plates) became available. PSP plates can contain phosphor material with color centers in their crystal lattice. When a PSP plate is exposed to radiation, electrons excited by the radiation are trapped in the color centers until they are excited by a laser beam scanning the plate surface. When the plate is scanned by the laser, the trapped excited electrons emit light, which is collected by a photomultiplier tube. The collected light is converted into a digital image. Compared to photographic plates and photographic film, PSP plates can be reused.

[0007] Another type of radiation detector is the radiation image intensifier (RIA). The components of an RIA are typically vacuum-sealed. Compared to photographic plates, photographic film, and PSP plates, RIAs can produce real-time images, meaning no post-exposure processing is required. Radiation first strikes an input phosphor (e.g., cesium iodide) and is converted into visible light. The visible light then strikes a photocathode (e.g., a thin metal layer containing cesium and antimony compounds) and causes electron emission. The number of emitted electrons is proportional to the intensity of the incident radiation. The emitted electrons are projected through electron optics onto an output phosphor, causing the output phosphor to produce a visible light image.

[0008] Scintillators operate in some ways similar to radiation image intensifiers because they (e.g., sodium iodide) absorb radiation and emit visible light, which can then be detected by a suitable image sensor for visible light. In a scintillator, visible light diffuses and scatters in all directions, thus reducing spatial resolution. Reducing the thickness of the scintillator helps improve spatial resolution but also reduces radiation absorption. Therefore, a trade-off must be struck between absorption efficiency and resolution.

[0009] Semiconductor radiation detectors primarily overcome this problem by directly converting radiation into electrical signals. A semiconductor radiation detector can include a semiconductor layer that absorbs radiation of the wavelength of interest. When radiating particles are absorbed in the semiconductor layer, multiple charge carriers (e.g., electrons and holes) are generated and swept toward electrical contacts on the semiconductor layer under an electric field. The cumbersome thermal management required in currently available semiconductor radiation detectors (e.g., Medipix) makes detectors with large areas and numerous pixels difficult or impossible to manufacture. Summary of the Invention

[0010] This document discloses an image sensor capable of moving along a first direction between multiple positions relative to a scene and capturing multiple partial images of the scene at the multiple positions respectively; the image sensor has an effective area and a dead zone, wherein the dead zone extends along a second direction that is not parallel to the first direction.

[0011] According to an embodiment, the image sensor is capable of forming an image of the scene from the plurality of local images.

[0012] According to an embodiment, when the image sensor is located at the plurality of locations, each point in the scene falls on the dead zone no more than once.

[0013] According to an embodiment, the dead zone extends across the effective area.

[0014] According to an embodiment, the dead zone divides the effective region into multiple spatially discontinuous parts.

[0015] According to an embodiment, the image sensor includes multiple radiation detectors.

[0016] According to an embodiment, the dead zone is part of the protective ring of the radiation detector.

[0017] According to an embodiment, the plurality of radiation detectors overlap each other.

[0018] According to an embodiment, at least one of the plurality of radiation detectors has an edge parallel to the first direction.

[0019] According to an embodiment, the image sensor includes a plurality of pixels; wherein the image sensor is configured to count the number of radiating particles incident on the pixels over a period of time.

[0020] According to an embodiment, the radiating particles are X-ray photons.

[0021] According to an embodiment, at least one of the plurality of radiation detectors includes: a radiation-absorbing layer including electrical contacts; a first voltage comparator configured to compare the voltage of the electrical contacts with a first threshold; a second voltage comparator configured to compare the voltage with a second threshold; a counter configured to record the number of radiation particles incident on the radiation-absorbing layer; and a controller; wherein the controller is configured to begin a time delay from the time when the first voltage comparator determines that the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold; wherein the controller is configured to activate the second voltage comparator during the time delay; and wherein the controller is configured to increment the number recorded by the counter by 1 when the second voltage comparator determines that the absolute value of the voltage is equal to or exceeds the absolute value of the second threshold.

[0022] According to an embodiment, the image sensor further includes an integrator electrically connected to the electrical contact, wherein the integrator is configured to collect charge carriers from the electrical contact.

[0023] According to an embodiment, the controller is configured to activate the second voltage comparator when the time delay begins or expires.

[0024] According to an embodiment, the controller is configured to connect the electrical contacts to electrical ground.

[0025] According to an embodiment, when the time delay period expires, the rate of change of the voltage is substantially zero.

[0026] According to an embodiment, the radiation-absorbing layer includes a diode.

[0027] According to an embodiment, the radiation-absorbing layer comprises monocrystalline silicon. Attached Figure Description

[0028] Figure 1 A method for moving an image sensor between multiple locations relative to a scene along a first direction, according to an embodiment, and capturing partial images of the scene at each of the multiple locations is illustrated schematically.

[0029] Figure 2A An image sensor including multiple radiation detectors is schematically shown according to an embodiment.

[0030] Figure 2BA top view of the first and second radiation detectors according to an embodiment is shown schematically.

[0031] Figures 2C to 2D Side views of two different arrangements of the radiation detector of the image sensor according to embodiments are shown schematically.

[0032] Figure 3 Multiple partial images of a scene portion captured by an image sensor according to an embodiment are schematically shown.

[0033] Figure 4 The radiation detector according to the embodiment is schematically shown to have a pixel array.

[0034] Figure 5A A cross-sectional view of a radiation detector according to an embodiment is shown schematically.

[0035] Figure 5B A detailed cross-sectional view of a radiation detector according to an embodiment is schematically shown.

[0036] Figure 5C An alternative detailed cross-sectional view of the radiation detector according to an embodiment is schematically shown.

[0037] Figure 6A and Figure 6B Each illustrates an embodiment. Figure 5A , Figure 5B and Figure 5C A component diagram of the electronic system of the radiation detector.

[0038] Figure 7 The diagram schematically illustrates the time-varying current (upper curve) flowing through the electrode or electrical contact of a diode or resistor exposed to radiation in an embodiment, and the corresponding time-varying voltage of the electrode (lower curve), the current being caused by charge carriers generated by radiation particles incident on the radiation-absorbing layer. Detailed Implementation

[0039] Figure 1 A method according to an embodiment is illustrated schematically. The method includes moving an image sensor 9000 along a first direction 951 between multiple locations relative to a scene 50 and capturing partial images of the scene 50 at each of the multiple locations.

[0040] exist Figure 1In the example shown, the image sensor 9000 can move along a first direction 951 from a first position 910 relative to the scene 50 to a second position 920. In one embodiment, at the first position 910 relative to the scene 50, the image sensor 9000 captures a partial image 1010 of a portion of the scene 50 using radiation from the radiation source 109 that has passed through the scene 50; and at the second position 920 relative to the scene 50, the image sensor 9000 captures another partial image 1020 of a portion of the scene 50 using radiation from the radiation source 109 that has passed through the scene 50. The image sensor 9000 may include a plurality of radiation detectors configured to receive radiation incident on it from the radiation source 109.

[0041] Figures 2A to 2D The image sensor 9000 according to an embodiment is schematically shown to include a plurality of radiation detectors 100 (e.g., a first radiation detector 100A, a second radiation detector 100B). The image sensor 9000 may include a bracket 107 such as a printed circuit board (PCB). Figure 2A A top view schematically illustrating a portion of an image sensor 9000 according to an embodiment is shown. Multiple radiation detectors 100 may be arranged on a flat surface of a support 107. Figures 2C to 2D Side views of two different arrangements of the radiation detector 100 of an image sensor 9000 according to one embodiment are schematically shown. Figure 2C In the example shown, multiple radiation detectors 100 can be mounted on a bracket 107, and the radiation receiving surface of each radiation detector can be tilted relative to the flat surface of the bracket 107. The multiple radiation detectors 100 can overlap each other. Figure 2D In the example shown, multiple radiation detectors 100 can be mounted on a bracket 107, and the radiation receiving surface of each radiation detector can be parallel to the flat surface of the bracket 107.

[0042] Figure 2B A schematic top view of a first radiation detector 100A and a second radiation detector 100B according to an embodiment is shown. The first radiation detector 100A may be arranged in a different orientation than the second radiation detector 100B. Figure 2BIn the illustrated example, the first radiation detector 100A may have an edge 921 parallel to the first direction 951. In one embodiment, the image sensor 9000 includes at least one first radiation detector 100A. The second radiation detector 100B may be tilted relative to the first direction 951, such that one edge 921 of the second radiation detector 100B may be parallel to the second direction 952. According to one embodiment, the second direction 952 is not parallel to the first direction 951. The second direction 952 may form an angle 953 relative to the first direction 951 (e.g., greater than 10 degrees, 20 degrees, or 30 degrees, etc.). As used herein, "forming an angle" means not parallel or perpendicular.

[0043] According to an embodiment, radiation detector 100 (such as...) Figure 2B The radiation detector 100 (as shown) has an effective region 190 and a dead zone 195. The effective region 190 may include a plurality of pixels 150, such that when the radiation detector 100 receives radiation from the radiation source 109 that has passed through the scene 50, the pixels 150 can detect incident particles of the radiation. The dead zone 195 may be a peripheral region surrounding the radiation receiving surface of the radiation detector 100, excluding pixels, so that radiation particles incident in the dead zone 195 may not be detected by the radiation detector 100. In one embodiment, the dead zone 195 is also part of a protective ring of the radiation detector 100. The dead zone 195 may extend across the effective region 190 in each radiation detector, respectively. In one embodiment, when multiple radiation detectors 100 (e.g., 100A, 100B, etc.) are arranged together to form a... Figure 2A In the image sensor 9000 shown, the effective area of ​​the image sensor 9000 is divided into multiple spatially discontinuous portions by a dead zone 195. The dead zone of the image sensor 9000 may include the dead zone of the radiation detector 100 and any gaps between the radiation detector 100. The effective area of ​​the image sensor 9000 is a combination of the effective areas 190 of the radiation detector 100.

[0044] Figure 3 Multiple images of a portion of scene 50 captured by an image sensor 9000 according to an embodiment are schematically shown. Figure 3 In the example shown, an image sensor 9000, including multiple radiation detectors 100, can move from position 910 to position 920 relative to scene 50 along a first direction 951. The image sensor 9000 can capture partial images 1010 and 1020 of portions of scene 50 at positions 910 and 920, respectively. The image sensor 9000 can stitch the partial images 1010 and 1020 together to form an image 1030 of the entire scene 50. Dead zones of the image sensor 9000 leave blanks in the partial images 1010 and 1020. Figure 3In the example shown, according to the embodiment, when the image sensor 9000 is at position 910, the dead zone leaves blank space 1015 in the partial image 1010; when the image sensor 9000 is at position 920, the dead zone leaves blank space 1025 in the partial image 1020. In one embodiment, the image sensor 9000 moves from position 910 to position 920 with a minimum step size 1040, such that when the image sensor 9000 is at multiple positions, each point in scene 50 falls on the dead zone of the image sensor 9000 no more than once. Therefore, when the image sensor 9000 is at position 920, the point of scene 50 that falls on the dead zone of the image sensor 9000 at position 910 can be captured by the image sensor 9000. Maintaining the minimum step size 1040 for each movement of the image sensor 9000 along the first direction 951, the image 1030 of the entire scene 50 can be formed by combining the partial images (i.e., 1010, 1020, etc.) captured by the image sensor 9000 at multiple positions.

[0045] Figure 4 The radiation detector 100 according to an embodiment is schematically shown to have an array of pixels 150. This array can be a rectangular array, a cellular array, a hexagonal array, or any other suitable array. Each pixel 150 can be configured to detect radiating particles incident thereon, measure the energy of the radiating particles, or both detect and measure. For example, each pixel 150 can be configured to count the number of radiating particles incident thereon whose energy falls into multiple intervals over a period of time. All pixels 150 can be configured to count the number of radiating particles incident thereon in multiple energy intervals within the same time period. Each pixel 150 can have its own analog-to-digital converter (ADC), which is configured to digitize the analog signal representing the energy of the incident radiating particles into a digital signal. The ADC can have a resolution of 10 bits or higher. Each pixel 150 can be configured to measure its dark current, for example, before or simultaneously with each radiating particle incident thereon. Each pixel 150 can be configured to subtract the contribution of the dark current from the energy of the radiating particles incident thereon. Pixels 150 can be configured to operate in parallel. For example, while one pixel 150 is measuring an incident radiation particle, another pixel 150 may be waiting for another radiation particle to arrive. Pixel 150 can be, but does not have to be, individually addressable. The radiation particle can be an X-ray photon.

[0046] Figure 5AA cross-sectional view of one of the radiation detectors 100 according to an embodiment is schematically shown. The radiation detector 100 may include a radiation-absorbing layer 110 and an electronics layer 120 (e.g., an ASIC) for processing or analyzing electrical signals generated in the radiation-absorbing layer 110 by incident radiation. In one embodiment, the radiation detector 100 of the image sensor 9000 does not include a scintillator. The radiation-absorbing layer 110 may include a semiconductor material, such as silicon, germanium, GaAs, CdTe, CdZnTe, or single-crystal silicon. The semiconductor may have a high-quality attenuation coefficient for the radiation energy of interest. The surface 103 of the radiation-absorbing layer 110, away from the electronics layer 120, is configured to receive radiation.

[0047] like Figure 5B A detailed cross-sectional view of the radiation detector 100 is shown. According to an embodiment, the radiation absorption layer 110 may include one or more diodes (e.g., pin or pn) formed by one or more discrete regions 114 of a first doped region 111 and a 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 regions 114 are separated from each other by either the first doped region 111 or the intrinsic region 112. The first doped region 111 and the second doped region 113 have opposite doping types (e.g., region 111 is p-type and region 113 is n-type, or region 111 is n-type and region 113 is p-type). Figure 5B In the example, each discrete region 114 of the second doped region 113 forms a diode with the first doped region 111 and an optional intrinsic region 112. That is, in Figure 5B In the example, the radiation-absorbing layer 110 has multiple diodes, each having a first doped region 111 as a common electrical contact. The first doped region 111 may also have discrete portions.

[0048] When a radiating particle strikes the radiation-absorbing layer 110, which includes a diode, the radiating particle can be absorbed and generate one or more charge carriers through various mechanisms. The radiating particle can generate 10 to 100,000 charge carriers. These charge carriers can drift to an electrical contact of one of the diodes under an electric field. This field can be an external electric field. The electrical contact 119B can include discrete portions, each of which is electrically in contact with a discrete region 114. In embodiments, the charge carriers can drift in various directions such that the charge carriers generated by a single radiating particle are substantially not shared by two different discrete regions 114 (here, "substantially not shared" means that less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these charge carriers flow to a different discrete region 114 compared to the rest). The charge carriers generated by radiating particles incident around a coverage area of ​​one of these discrete regions 114 are substantially not shared with the other of these discrete regions 114. Pixel 150 associated with discrete region 114 can be a region surrounding 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 thereat an angle of 0° flow toward 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.

[0049] like Figure 5C An alternative detailed cross-sectional view of the radiation detector 100 is shown. According to an embodiment, the radiation absorption layer 110 may include a resistor made of a semiconductor material such as silicon, germanium, GaAs, CdTe, CdZnTe, or combinations thereof, but not a diode. This semiconductor may have a high-quality attenuation coefficient for the radiation energy of interest.

[0050] When a radiating particle strikes a radiation-absorbing layer 110 that includes resistors but not diodes, it can be absorbed and generate one or more charge carriers through various mechanisms. The radiating particle can generate 10 to 100,000 charge carriers. These charge carriers can drift to electrical contacts 119A and 119B under an electric field. This field can be an external electric field. Electrical contact 119B includes discrete portions. In an embodiment, charge carriers can drift in various directions such that charge carriers generated by a single radiating particle are substantially not shared by the two distinct discrete portions of electrical contact 119B (here, "substantially not shared" means that less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these charge carriers flow to a different discrete portion compared to the remaining charge carriers). Charge carriers generated by a radiating particle incident on the coverage area of ​​one of these discrete portions of electrical contact 119B are substantially not shared with the other of these discrete portions of electrical contact 119B. Pixel 150 associated with a discrete portion of electrical contact 119B can be a region surrounding the discrete portion, 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 thereat at an angle of 0° flow to the discrete portion of electrical contact 119B. That is, less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these charge carriers flow through a pixel associated with a discrete portion of electrical contact 119B.

[0051] Electronics layer 120 may include an electronic system 121 suitable for processing or interpreting signals generated by radiating particles incident on radiation-absorbing layer 110. Electronics system 121 may include analog circuitry such as filter networks, amplifiers, integrators, and comparators, or digital circuitry such as microprocessors and memories. Electronics system 121 may include components shared by all pixels or components dedicated to a single pixel. For example, electronic system 121 may include an amplifier dedicated to each pixel and a microprocessor shared across all pixels. Electronics system 121 may be electrically connected to pixels via vias 131. The space between vias may be filled with filler material 130, which may increase the mechanical stability of the connection between electronics layer 120 and radiation-absorbing layer 110. Other bonding techniques may connect electronics system 121 to pixels without using vias.

[0052] Figure 6A and Figure 6B All diagrams show component figures of the electronic system 121 according to an embodiment. The electronic system 121 may include a first voltage comparator 301, a second voltage comparator 302, a counter 320, a switch 305, an optional voltmeter 306, and a controller 310.

[0053] A first voltage comparator 301 is configured to compare the voltage of at least one electrical contact 119B with a first threshold. The first voltage comparator 301 can be configured to directly monitor the voltage or to calculate the voltage by integrating the current flowing through the electrical contact 119B over a period of time. The first voltage comparator 301 can be controllably activated or deactivated by a controller 310. The first voltage comparator 301 can be a continuous comparator; that is, the first voltage comparator 301 can be configured to be continuously activated and continuously monitor the voltage. The first voltage comparator 301 can be a clock-controlled comparator. The first threshold can be 5-10%, 10%-20%, 20-30%, 30-40%, or 40-50% of the maximum voltage that an incident radiating particle can generate on the electrical contact 119B. The maximum voltage can depend on the energy of the incident radiating particle, the material of the radiation-absorbing layer 110, and other factors. For example, the first threshold can be 50mV, 100mV, 150mV, or 200mV.

[0054] A second voltage comparator 302 is configured to compare the voltage with a second threshold. The second voltage comparator 302 can be configured to directly monitor the voltage or calculate the voltage by integrating the current flowing through the diode or electrical contact over a time period. The second voltage comparator 302 can be a continuous comparator. The second voltage comparator 302 can be controllably activated or deactivated by the controller 310. When the second voltage comparator 302 is deactivated, its power consumption can be less than 1%, 5%, 10%, or 20% of the power consumption when activated. The absolute value of the second threshold is greater than the absolute value of the first threshold. As used herein, the term "absolute value" or "modulus" for the real number x is used. The second threshold is a non-negative value of x, regardless of its sign. That is, the second threshold can be 200%-300% of the first threshold. The second threshold can be at least 50% of the maximum voltage that an incident radiation particle can generate on the electrical contact 119B. For example, the second threshold can be 100mV, 150mV, 200mV, 250mV, or 300mV. The second voltage comparator 302 and the first voltage comparator 301 can be the same component. That is, the system 121 can have a voltage comparator that can compare the voltage with two different thresholds at different times.

[0055] The first voltage comparator 301 or the second voltage comparator 302 may include one or more operational amplifiers or any other suitable circuitry. The first voltage comparator 301 or the second voltage comparator 302 may be high-speed to allow the electronic system 121 to operate under high-flux incident radiation particles. However, high speed typically comes at the cost of power consumption.

[0056] The counter 320 is configured to record the number of radiation particles incident on the radiation-absorbing layer 110 containing the pixel 150. The counter 320 may be a software component (e.g., a number stored in computer memory) or a hardware component (e.g., a 4017 IC and a 7490 IC).

[0057] Controller 310 may be a hardware component, such as a microcontroller and a microprocessor. Controller 310 is configured to begin a time delay from the time when the first voltage comparator 301 determines that the absolute value of the voltage is equal to or exceeds the absolute value of a first threshold (e.g., the absolute value of the voltage increases from below the first threshold to a value equal to or above the first threshold). Absolute values ​​are used here because the voltage can be negative or positive, depending on whether the cathode or anode of a diode is used or which electrical contact is used. Controller 310 may be configured to deactivate any other circuitry not required for the operation of the second voltage comparator 302, counter 320, and the first voltage comparator 301 before the time when the first voltage comparator 301 determines that the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold. The time delay may expire before or after the voltage becomes stable, i.e., the rate of change of the voltage is substantially zero. The phrase "the rate of change of the voltage is substantially zero" means that the voltage change over time is less than 0.1% / ns. The phrase "the rate of change of the voltage is substantially non-zero" means that the voltage change over time is at least 0.1% / ns.

[0058] Controller 310 can be configured to activate the second voltage comparator during a time delay period (including the start and end of the delay). In one embodiment, controller 310 is configured to activate the second voltage comparator at the start or end of the time delay. The term "activate" means to bring a component into an operating state (e.g., by sending a signal such as a voltage pulse or logic level, by providing power, etc.). The term "deactivate" means to bring a component into a non-operating state (e.g., by sending a signal such as a voltage pulse or logic level, by cutting off power, etc.). The operating state may have higher power consumption than the non-operating state (e.g., 10 times, 100 times, 1000 times that of the non-operating state). Controller 310 itself can be deactivated until the output of the first voltage comparator 301 activates controller 310 when the absolute value of the voltage is equal to or exceeds the absolute value of a first threshold.

[0059] The controller 310 can be configured to increment at least one of the quantities recorded by the counter 320 if the second voltage comparator 302 determines that the absolute value of the voltage is equal to or exceeds the absolute value of the second threshold during the time delay.

[0060] Controller 310 can be configured to cause an optional voltmeter 306 to measure the voltage upon the expiration of a time delay. Controller 310 can be configured to connect electrical contact 119B to electrical ground to reset the voltage and discharge any charge carriers accumulated on electrical contact 119B. In one embodiment, electrical contact 119B is connected to electrical ground after the time delay has elapsed. In another embodiment, electrical contact 119B is connected to electrical ground for a limited reset period. Controller 310 can connect electrical contact 119B to electrical ground via a control switch 305. This switch can be a transistor such as a field-effect transistor (FET).

[0061] In one embodiment, system 121 does not have an analog filter network (e.g., an RC network). In this embodiment, system 121 has no analog circuitry.

[0062] The voltmeter 306 can feed the voltage it measures as an analog or digital signal to the controller 310.

[0063] Electronic system 121 may include an integrator 309 electrically connected to electrical contact 119B, wherein the integrator is configured to collect charge carriers from electrical contact 119B. Integrator 309 may include a capacitor in the feedback path of the amplifier. An amplifier configured in this way is called a capacitive transimpedance amplifier (CTIA). CTIA has a high dynamic range by preventing amplifier saturation and improves the signal-to-noise ratio by limiting the bandwidth in the signal path. Charge carriers from electrical contact 119B accumulate on the capacitor during a time period (“integration period”). After the integration period ends, the capacitor voltage is sampled, and then the capacitor voltage is reset by a reset switch. Integrator 309 may include a capacitor directly connected to electrical contact 119B.

[0064] Figure 7The diagram schematically illustrates the time-varying current (upper curve) flowing through electrical contact 119B caused by charge carriers generated by radiating particles incident on pixel 150 surrounding electrical contact 119B, and the corresponding time-varying voltage of electrical contact 119B (lower curve). Voltage can be the integral of current relative to time. At time t0, radiating particles strike pixel 150, charge carriers begin to be generated in pixel 150, current begins to flow through electrical contact 119B, and the absolute value of the voltage at electrical contact 119B begins to increase. At time t1, a first voltage comparator 301 determines that the absolute value of the voltage is equal to or exceeds the absolute value of a first threshold V1, controller 310 begins a time delay TD1, and controller 310 may deactivate the first voltage comparator 301 at the start of TD1. If controller 310 is deactivated before t1, controller 310 is activated at t1. During TD1, controller 310 activates a second voltage comparator 302. The term "during" as used herein refers to the start and end (i.e., the end) of a period, and any time in between. For example, controller 310 may activate the second voltage comparator 302 when TD1 expires. If, during TD1, the second voltage comparator 302 determines at time t2 that the absolute value of the voltage is equal to or exceeds the absolute value of the second threshold V2, then controller 310 waits for the voltage to stabilize. The voltage at time t1 stabilizes as all charge carriers generated by the radiating particles drift outside the radiation absorption layer 110. e Stable. At time t s The time delay TD1 expires. At time t e Subsequently, controller 310 causes voltmeter 306 to digitize the voltage and determine which interval the energy of the radiating particle falls into. Controller 310 then increments counter 320 by 1 corresponding to the number recorded for that interval. Figure 7 In the example, time t s At time t e Then; that is, after all the charge carriers generated by the radiating particles have drifted outside the radiation absorption layer 110, the TD1 period expires. If time t cannot be easily measured... e Therefore, TD1 can be empirically selected to allow sufficient time to collect substantially all the charge carriers generated by the radiating particle, but not too long, to avoid the risk of another incident radiating particle. That is, TD1 can be empirically selected, thus the time t can be empirically determined. s At time t e After that. Time t s It doesn't necessarily have to be at time t e Subsequently, because controller 310 can ignore TD1 upon reaching V2 and wait for time t e Therefore, the rate of change of the difference between voltage and the contribution of dark current to voltage is in t eThe value is essentially zero. Controller 310 can be configured to activate the second voltage comparator 302 at the expiration of TD1 or at t2 or any time in between.

[0065] At time t e The voltage is proportional to the amount of charge carriers generated by the radiating particles, and is related to the energy of the radiating particles. Controller 310 can be configured to determine the energy of the radiating particles using voltmeter 306.

[0066] After TD1 expires or voltmeter 306 digitizes (whichever is later), controller 310 connects electrical contact 119B to electrical ground during the reset period (RST) to allow charge carriers accumulated on electrical contact 119B to flow to ground and reset the voltage. After RST, electronic system 121 is ready to detect another incident radiation particle. If the first voltage comparator 301 has been deactivated, controller 310 can activate it at any time before the RST expires. If controller 310 has been deactivated, it can be activated before the RST expires.

[0067] While 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 illustrative purposes and are not intended to be limiting, wherein the true scope and spirit are indicated by the following claims.

Claims

1. An image sensor, wherein, The image sensor is capable of moving along a first direction between multiple positions relative to the scene and capturing multiple partial images of the scene at each of the multiple positions. The image sensor has an effective area and a dead zone, wherein the dead zone extends along a second direction that is not parallel to the first direction.

2. The image sensor according to claim 1, wherein, The image sensor is capable of forming an image of the scene from the multiple local images.

3. The image sensor according to claim 1, wherein, When the image sensor is located at the plurality of locations, each point in the scene falls on the dead zone no more than once.

4. The image sensor according to claim 1, wherein, The dead zone extends across the effective area.

5. The image sensor according to claim 1, wherein, The dead zone divides the effective area into multiple spatially discontinuous parts.

6. The image sensor according to claim 1, wherein, The image sensor includes multiple radiation detectors.

7. The image sensor according to claim 6, wherein, The dead zone is part of the protective ring of the radiation detector.

8. The image sensor according to claim 6, wherein, The multiple radiation detectors overlap each other.

9. The image sensor according to claim 6, wherein, At least one of the plurality of radiation detectors has an edge parallel to the first direction.

10. The image sensor according to claim 1, wherein, The image sensor includes a plurality of pixels; wherein the image sensor is configured to count the number of radiating particles incident on the pixels over a period of time.

11. The image sensor according to claim 10, wherein, The radiating particles are X-ray photons.

12. The image sensor according to claim 6, wherein, At least one of the plurality of radiation detectors includes: Including the radiation-absorbing layer of the electrical contacts; A first voltage comparator is configured to compare the voltage of the electrical contact with a first threshold. A second voltage comparator is configured to compare the voltage with a second threshold. A counter configured to record the number of radiation particles incident on the radiation-absorbing layer; Controller; The controller is configured to begin a time delay from the time when the first voltage comparator determines that the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold. The controller is configured to activate the second voltage comparator during the time delay. The controller is configured to increment the number of records recorded by the counter by 1 when the second voltage comparator determines that the absolute value of the voltage is equal to or exceeds the absolute value of the second threshold.

13. The image sensor according to claim 12, wherein, The image sensor also includes an integrator electrically connected to the electrical contact, wherein the integrator is configured to collect charge carriers from the electrical contact.

14. The image sensor according to claim 12, wherein, The controller is configured to activate the second voltage comparator when the time delay begins or expires.

15. The image sensor according to claim 12, wherein, The controller is configured to connect the electrical contacts to electrical ground.

16. The image sensor according to claim 12, wherein, When the time delay expires, the rate of change of the voltage is essentially zero.

17. The image sensor according to claim 12, wherein, The radiation-absorbing layer includes a diode.

18. The image sensor according to claim 12, wherein, The radiation-absorbing layer comprises monocrystalline silicon.

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