Vacuum health detection for imaging systems and methods

Abstract

Techniques are provided for facilitating vacuum health detection of imaging systems and methods. In one example, an imaging device includes a detector configured to generate a first reference signal. The imaging device also includes a buffer circuit configured to store a value of the first reference signal. The imaging device further includes a processing circuit coupled to the buffer circuit. The processing circuit is configured to determine a first predetermined value based on a first temperature associated with the detector. The processing circuit is also configured to determine a vacuum integrity associated with the detector based on at least the value of the first reference signal and the first predetermined value. Related methods and systems are also provided.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit and priority of U.S. Patent Application No. 63 / 054,729, filed July 21, 2020, entitled “Vacuum Health Detection for Imaging Systems and Methods,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] One or more embodiments generally relate to imaging, and more specifically, for example, to vacuum health detection for imaging systems and methods. Background Technology

[0004] Imaging systems can include arrays of detectors, where each detector serves as a pixel to produce a portion of a two-dimensional image. A wide variety of image detectors exist, such as visible light image detectors, infrared image detectors, or other types of image detectors that can be incorporated into an image detector array for capturing images. As an example, multiple sensors can be incorporated into an image detector array to detect electromagnetic (EM) radiation at a desired wavelength. In some cases, such as for infrared imaging, the readout of image data captured by the detectors can be performed by a readout integrated circuit (ROIC) in a time-multiplexed manner. The readout image data can be transferred to other circuitry, such as for processing, storage, and / or display. In some cases, the combination of a detector array and a ROIC can be referred to as a focal plane array (FPA). Advances in FPA and image processing technologies have led to increased functionality and complexity in the resulting imaging systems. Summary of the Invention

[0005] In one or more embodiments, the imaging apparatus includes a detector configured to generate a first reference signal. The imaging apparatus also includes a buffer circuit configured to store a value of the first reference signal. The imaging apparatus further includes processing circuitry coupled to the buffer circuitry. The processing circuitry is configured to determine a first predetermined value based on a first temperature associated with the detector. The processing circuitry is also configured to determine vacuum integrity associated with the detector based at least on the value of the first reference signal and the first predetermined value.

[0006] In one or more embodiments, a method includes generating a first reference signal by a detector. The method further includes storing the value of the first reference signal by buffer circuitry. The method further includes determining a first predetermined value by processing circuitry based on a first temperature associated with the detector. The method further includes determining a vacuum integrity associated with the detector by processing circuitry based at least on the value of the first reference signal and the first predetermined value.

[0007] The scope of this disclosure is defined by the claims, which are incorporated herein by reference. Those skilled in the art will gain a more complete understanding of embodiments of this disclosure and realize their additional advantages by considering the following detailed description of one or more embodiments. Reference will be made to the accompanying drawings, which are briefly described first. Attached Figure Description

[0008] Figure 1 A block diagram of an example imaging system according to one or more embodiments of the present disclosure is shown.

[0009] Figure 2 An example calorimeter circuit according to one or more embodiments of the present disclosure is shown.

[0010] Figure 3 An example calorimeter circuit according to one or more embodiments of the present disclosure is shown.

[0011] Figure 4 An example system for facilitating vacuum health detection is shown according to one or more embodiments of the present disclosure.

[0012] Figure 5 A flowchart illustrating an example process for facilitating vacuum health detection according to one or more embodiments of the present disclosure is shown.

[0013] Figure 6 An example bias circuit for facilitating vacuum detection is shown according to one or more embodiments of the present disclosure.

[0014] Figure 7 The graph shows the ramp voltage associated with the ramp generator and the digital count value associated with the counter circuit as a function of time.

[0015] Figure 8 A graph showing the relationship between temperature over time and thermal transconductance at different ambient temperatures, according to one or more embodiments of the present disclosure.

[0016] Figure 9 A graph showing the relationship between a reference voltage signal varying with temperature and thermal transconductance according to one or more embodiments of the present disclosure is shown.

[0017] Figure 10 A graph showing the relationship between temperature and the difference in reference voltage signals under two different thermal transconductances, varying with frame number, according to one or more embodiments of the present disclosure.

[0018] Figure 11 An example calorimeter circuit according to one or more embodiments of the present disclosure is shown.

[0019] The embodiments and advantages of this disclosure are best understood by referring to the following detailed description. It should be noted that the dimensions of the individual components and the distances between them are not drawn to scale in the figures. It should be understood that similar reference numerals are used to identify similar elements shown in one or more figures. Detailed Implementation

[0020] The detailed description given below is intended as a description of various configurations of the subject matter, and not as representing the only configuration in which the subject matter can be practiced. The accompanying drawings are incorporated herein and form part of the detailed description. The detailed description includes specific details and is intended to provide a thorough understanding of the subject matter. However, it will be clear and apparent to those skilled in the art that the subject matter is not limited to the specific details set forth herein and can be practiced using one or more embodiments. In one or more instances, structures and components are shown in block diagram form to avoid obscuring the concept of the subject matter. One or more embodiments of this disclosure are illustrated by one or more accompanying drawings and / or described in conjunction with one or more accompanying drawings, and are set forth in the claims.

[0021] Various systems and methods are provided to facilitate vacuum health detection. In various embodiments, imaging systems and methods may use detectors based on radiometric calorimeters. Imaging apparatuses according to various embodiments may include an FPA having detectors and readout circuitry. Detectors may also be referred to as detector pixels, detector elements, or simply pixels or elements. Each detector may capture a portion of the incident scene (e.g., incident EM radiation) and generate an associated detector output. Detector outputs may be electrical signals (e.g., voltage or photocurrent) and may be referred to as pixel outputs or image data. Readout circuitry performs readout to obtain image data from each detector indicating the EM radiation detected by the detector.

[0022] In some aspects, an FPA may include effective unit cells and reference unit cells. Each effective unit cell may include a detector. Each reference unit cell may include a detector and a structure (e.g., shutter, cover, shroud, blade) or a portion thereof that selectively blocks the detector of the reference unit cell from the scene (e.g., incident or external radiation, such as thermal radiation) incident on the unit cell array. This structure may be used to provide / present a uniform scene to the detector of the reference unit cell. The detector of the reference unit cell is effectively blocked from seeing the scene. Therefore, the reference unit cell and its detector may be referred to as a blind unit cell and a blind detector, respectively.

[0023] The FPA (e.g., effective and blind detectors and readout circuitry) can be housed within a vacuum package to provide a high vacuum environment that facilitates obtaining the desired sensitivity from the detector. Vacuum integrity can decrease over time due to various factors, such as degassing and / or leakage. For example, when a vacuum is lost, air and / or other gases may enter the sensor cavity and adversely affect the thermal isolation of the detector. Such a reduction in vacuum integrity can lead to a gradual loss of vacuum pressure and thus reduce the sensitivity and overall performance of the FPA. The reference detector of the FPA is shielded from incident or external radiation and, similar to the effective detector, is substantially thermally isolated from the substrate. The effective detector and the reference detector can share various properties, such as operating within the same vacuum cavity and sharing noise properties (e.g., temporal noise properties).

[0024] In some embodiments, the integrity of the vacuum can be achieved by saving / storing the reference signal V generated by the blind detector. REF The value is used to determine this. On one hand, the reference signal V... REF This can be referred to as the bias setting reference signal. Reference signal V REF This can be used to compensate for the self-heating of the effective detector (e.g., pulse bias heating). Therefore, the reference signal V REF This can also be called a compensation signal or anti-ramp signal (e.g., to compensate for the ramp / slope associated with self-heating). In some cases, a reference signal can be generated for each row of valid detectors. For example, when reading out a detector array row by row, the line can be called a row. Reference signal V REF Different slopes can be achieved depending on the temperature. In one embodiment, the temperature can be the temperature of the FPA's readout circuitry (e.g., ROIC), which can also be referred to as the ambient temperature or substrate temperature. On the one hand, hotter temperatures are associated with higher pulse bias heating and therefore with a larger slope. When the vacuum in which the FPA and detector reside has high quality, the reference signal V... REF It has a large slope because the pulse bias heating does not decrease due to thermal shunting to air. As the vacuum decreases, the reference signal V buffered to the detector... REF The slope flattens out. At this point, as the vacuum decreases, pixels may become thermally diverted to the temperature of the air surrounding them, resulting in a reduced pixel responsiveness to the scene.

[0025] During calibration (e.g., in the factory), due to the reference signal V REF The final value will vary not only with vacuum but also with temperature. Therefore, under high-quality vacuum conditions, a reference signal V for the temperature (e.g., ROIC temperature) within the operating temperature range of the imaging device can be determined and preserved. REF The value of the reference signal V. REFSuch a value can be called the expected reference signal value or the calibration reference signal value. For example, lookup tables, equations, and / or other data structures / relationships can be used to store and / or calculate the reference signal V for the temperature within the operating temperature range. REF The value of .

[0026] In the field, for a blind detector at a given temperature (e.g., measured by a temperature sensor of the imaging device or otherwise coupled to a temperature sensor of the imaging device), if the reference signal V generated by the blind detector... REF If the value deviates from the expected reference signal value at that temperature by more than a threshold amount, it can be determined that the vacuum in which the effective and blind detectors operate has been significantly reduced. In various respects, the ROIC temperature can be considered the temperature of the blind detector. This threshold amount can be selected based on the application (e.g., requirements associated with image data integrity), cost considerations, etc. For example, this threshold amount can be associated with a certain amount / percentage of vacuum loss (e.g., 10% vacuum loss). In some cases, when such a deviation is detected, the imaging system electronics can flag a warning to the imaging equipment and / or user that the detector may experience performance degradation due to vacuum loss / reduction (e.g., the image data generated by the detector may deteriorate). If the reference signal V generated by the blind detector... REF If the value deviates from the expected reference signal value at that temperature within a threshold amount, it can be determined that the vacuum has not decreased significantly (e.g., not to the extent that it requires the attention of the user or imaging equipment), although the deviation can be stored and / or reported (e.g., to the imaging system electronics and / or the user) for monitoring purposes.

[0027] Typically, vacuum integrity monitoring / verification of imaging equipment can be performed to detect the presence or absence of erroneous states (e.g., also known as failure modes) and report diagnoses (e.g., to the user). It should be noted that in some cases, the detection of the presence or absence of an erroneous state may be associated with one or more confidence levels. Such confidence levels can be indicators of the probability of false positives and false negatives. Such vacuum integrity verification of imaging equipment can be performed to ensure that the image data provided by the imaging equipment is not corrupted. Corrupted image data can lead to false positives and / or failures in various applications, such as the inability to detect objects in the perception system of an autonomous vehicle for autonomous vehicle applications. Reported diagnoses can help mitigate any detected erroneous states.

[0028] Notifications (e.g., diagnostic flags) can be used to alert a user to a detected error state, enabling the user to troubleshoot and / or perform mitigation actions. In one aspect, a diagnostic flag can be, or can cause, a general-purpose input / output (GPIO) interrupt sent to the appropriate circuitry. As a non-limiting example, mitigation actions may include adjusting the processing performed by the imaging device (e.g., the processor of the imaging device) due to a loss of vacuum, resetting the imaging device (or a portion thereof) to determine if the error is transient, cycling the power supply associated with the imaging device (or a portion thereof) to determine if the error is transient, or replacing the imaging device (e.g., replacing the camera containing the imaging device with a different camera). As a non-limiting example, the error state can be conveyed to the user via a display on a user device (e.g., a mobile phone), a display on a camera including the imaging device, and / or by other means. Such alerts can be visible alerts, such as text or light pulses emitted by a light-emitting diode communicatively connected to the imaging device, and / or audible alerts, such as a beeping sound emitted by a speaker communicatively connected to the imaging device.

[0029] Various embodiments of the methods and systems disclosed herein may be included in or implemented as various devices and systems, such as visible light imaging systems, infrared imaging systems (e.g., thermal infrared imaging systems), imaging systems with visible light and infrared imaging capabilities, mobile digital cameras, video surveillance systems, video processing systems, or other systems or devices that may require image data in one or more portions of the EM spectrum.

[0030] Now refer to the attached diagram, Figure 1 A block diagram of an example imaging system 100 (e.g., an infrared camera) according to one or more embodiments of the present disclosure is shown. However, not all depicted components are necessary, and one or more embodiments may include additional components not shown in the figures. Variations in the arrangement and type of components may be made without departing from the spirit or scope of the claims set forth herein. Additional components, different components, and / or fewer components may be provided.

[0031] According to embodiments of this disclosure, imaging system 100 can be used to capture and process images. Imaging system 100 can represent any type of imaging system that detects one or more ranges (e.g., bands) of EM radiation and provides representative data (e.g., one or more still image frames or video image frames). Imaging system 100 may include a housing that at least partially surrounds the components of imaging system 100 to facilitate compactness and protection of imaging system 100. For example, Figure 1 The solid-line frame marked 175 represents the housing of the imaging system 100. The housing may contain more than... Figure 1The solid-line boxes in the figures depict components of the imaging system 100 that are more, fewer, and / or different. In one embodiment, the imaging system 100 may include a portable device and may be coupled, for example, to a vehicle or non-mobile device that requires the storage and / or display of images. The vehicle may be a land-based vehicle (e.g., a car, truck), a sea-based vehicle, an aircraft (e.g., an unmanned aerial vehicle (UAV)), a space vehicle, or any type of vehicle that may generally contain the imaging system 100 (e.g., mounted therein, mounted on therein, etc.). In another example, the imaging system 100 may be coupled to various types of fixed locations (e.g., home security mounts, campsite or outdoor mounts, or other locations) via one or more types of mounts.

[0032] According to one embodiment, the imaging system 100 includes a processing unit 105, a memory unit 110, an image capture unit 115, an image interface 120, a control unit 125, a display unit 130, a sensing unit 135, and / or a network interface 140. According to various embodiments, the processing unit 105 includes one or more of a processor, microprocessor, central processing unit (CPU), graphics processing unit (GPU), single-core processor, multi-core processor, microcontroller, programmable logic device (PLD) (e.g., field-programmable gate array (FPGA)), application-specific integrated circuit (ASIC), digital signal processing (DSP) device, or other logic devices that can be hardwired, execute software instructions, or a combination of both to perform the various operations discussed herein with respect to embodiments of this disclosure. The processing unit 105 may be configured to connect and communicate with various other components of the imaging system 100 (e.g., 110, 115, 120, 125, 130, 135, 140, etc.) to perform such operations. For example, processing unit 105 may be configured to process captured image data received from imaging capture unit 115, store image data in memory unit 110, and / or retrieve stored image data from memory unit 110. In one aspect, processing unit 105 may be configured to perform various system control operations (e.g., controlling communication and operation of various components of imaging system 100) and other image processing operations (e.g., data conversion, video analysis, etc.).

[0033] Processing unit 105 can perform operations to process pixel values ​​received from readout circuitry 170 of imaging capture unit 115 (e.g., as part of a frame). As a non-limiting example, processing unit 105 can perform operations such as non-uniformity correction (NUC) (e.g., flat field correction (FFC) or other calibration techniques), spatial and / or temporal filtering, and / or radiometric conversion of pixel values. Processing unit 105 can include a combination of hardware and software processing functions and can be configured / set in other units and / or communicatively coupled to other units to execute appropriate instructions, such as software instructions and / or processing parameters (e.g., filter coefficients, NUC correction terms) stored in memory unit 110. In various embodiments, processing unit 105 can be configured to execute software instructions stored in memory unit 110 to perform various methods, processes, or operations as described herein. In some aspects, the readout circuitry 170 and / or processing unit 105 may include and / or be coupled to circuitry to generate and provide timing / clock signals and / or control signals to facilitate the readout of image data captured by the image detector circuitry 165 of the imaging capture unit 115. As an example, such signals may include an F-signal associated with the start of the image. SYNC Signals and / or End of Frame (EOF) associated with the end of the image.

[0034] In one embodiment, memory component 110 includes one or more memory devices configured to store data and information, including infrared image data and information. Memory component 110 may include one or more different types of memory devices, including volatile and non-volatile memory devices, such as random access memory (RAM), dynamic RAM (DRAM), static RAM (SRAM), non-volatile random access memory (NVRAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, hard disk drive, and / or other types of memory. As described above, processing component 105 may be configured to execute software instructions stored in memory component 110 to perform method and process steps and / or operations. Processing component 105 and / or image interface 120 may be configured to store images or digital image data captured by imaging capture component 115 in memory component 110. Processing component 105 may be configured to store processed still images and / or video images in memory component 110.

[0035] In some embodiments, a separate machine-readable medium 145 (e.g., memory, such as a hard disk drive, compact disk, digital video disk, or flash memory) may store software instructions and / or configuration data that can be executed or accessed by a computer (e.g., a logic device- or processor-based system) to perform various methods and operations, such as those associated with processing image data. In one aspect, the machine-readable medium 145 may be portable and / or located separately from the imaging system 100, wherein the stored software instructions and / or data are provided to the imaging system 100 by coupling the machine-readable medium 145 to the imaging system 100 and / or by downloading it from the machine-readable medium 145 via the imaging system 100 (e.g., via a wired link and / or a wireless link). It should be understood that various modules may be integrated in software and / or hardware as part of the processing component 105, wherein code for the module (e.g., software or configuration data) is stored, for example, in the memory component 110.

[0036] Imaging system 100 may represent an imaging device, such as a video and / or still camera, to capture and process images and / or videos of scene 160. In this regard, image capture component 115 of imaging system 100 may be configured to capture images (e.g., still images and / or video images) of scene 160 in a specific spectrum or modality. Image capture component 115 includes image detector circuitry 165 (e.g., thermal infrared detection circuitry) and readout circuitry 170 (e.g., ROIC). In some cases, image capture component 115 does not have a shutter, such that image detector circuitry 165 is exposed to the scene surrounded by the field of view of image capture component 115. For example, image capture component 115 may include an IR imaging sensor (e.g., an IR imaging sensor array) configured to detect IR radiation in the near, mid, and / or far IR spectra and provide an IR image (e.g., IR image data or signal) representing the IR radiation from scene 160. For example, image detector circuitry 165 may capture (e.g., detect, sense) IR radiation with wavelengths ranging from about 700 nm to about 2 mm or a portion thereof. For example, in some aspects, the image detector circuit 165 may be sensitive (e.g., better detectable) to short-wave IR (SWIR) radiation, mid-wave IR (MWIR) radiation (e.g., EM radiation with wavelengths from 2 μm to 5 μm), and / or long-wave IR (LWIR) radiation (e.g., EM radiation with wavelengths from 7 μm to 14 μm) or any desired IR wavelength (e.g., typically in the range of 0.7 μm to 14 μm). In other aspects, the image detector circuit 165 may capture radiation from one or more other bands of the EM spectrum, such as visible light, ultraviolet light, etc.

[0037] Image detector circuit 165 can capture image data associated with scene 160. To capture an image, image detector circuit 165 can detect image data of scene 160 (e.g., in the form of EM radiation) and generate pixel values ​​for the image based on scene 160. The image may be referred to as a frame or image frame. In some cases, image detector circuit 165 may include a detector array (e.g., also referred to as a pixel array) that can detect radiation in a specific band, convert the detected radiation into electrical signals (e.g., voltage, current, etc.), and generate pixel values ​​based on the electrical signals. Each detector in the array can capture a corresponding portion of the image data and generate pixel values ​​based on the corresponding portion captured by the detector. The pixel values ​​generated by the detector may be referred to as the detector output. As a non-limiting example, each detector may be a photodetector, such as an avalanche photodiode, an infrared photodetector, a quantum well infrared photodetector, a microbolometer, or other detector capable of converting EM radiation (e.g., EM radiation at a specific wavelength) into pixel values. The detector array may be arranged in rows and columns.

[0038] An image can be, or can be considered, a data structure comprising pixels and a representation of image data associated with scene 160, wherein each pixel has a pixel value representing EM radiation emitted or reflected from a portion of the scene and received by a detector that generates pixel values. Contextually, a pixel may refer to a detector of image detector circuit 165 that generates associated pixel values ​​or a pixel (e.g., pixel location, pixel coordinates) of an image formed by the generated pixel values.

[0039] In one aspect, the pixel value generated by the image detector circuit 165 can be represented by a digital count value generated based on an electrical signal obtained from the radiation detected from the conversion. For example, where the image detector circuit 165 includes or is otherwise coupled to an ADC circuit, the ADC circuit can generate a digital count value based on the electrical signal. For an ADC circuit that can use 14 bits to represent the electrical signal, the digital count value can range from 0 to 16383. In such a case, the pixel value of the detector can be a digital count value output from the ADC circuit. In other cases (e.g., in the absence of an ADC circuit), the pixel value can be analog in nature, and its value is or indicates the value of the electrical signal. As an example, for infrared imaging, a larger amount of IR radiation incident on and detected by the image detector circuit 165 (e.g., an IR image detector circuit) is associated with a higher digital count value and a higher temperature.

[0040] The readout circuit 170 can serve as an interface between the image detector circuit 165, which detects image data, and the processing unit 105, which processes the detected image data read out by the readout circuit 170, wherein the image interface 120 facilitates the transfer of data from the readout circuit 170 to the processing unit 105. The image capture frame rate can refer to the rate at which the image detector circuit 165 detects images sequentially and the images are provided to the processing unit 105 by the readout circuit 170 (e.g., images per second). The readout circuit 170 can read out the pixel values ​​generated by the image detector circuit 165 based on the integration time (e.g., also referred to as the integration period).

[0041] In various embodiments, the combination of image detector circuitry 165 and readout circuitry 170 may be, may include, or may be provided together as an FPA. In some aspects, image detector circuitry 165 may be a thermal image detector circuit including a microbolometer array, and the combination of image detector circuitry 165 and readout circuitry 170 may be referred to as a microbolometer FPA. In some cases, the microbolometer array may be arranged in rows and columns. The microbolometers may detect IR radiation and generate pixel values ​​based on the detected IR radiation. For example, in some cases, the microbolometer may be a thermal IR detector that detects IR radiation in the form of thermal energy and generates pixel values ​​based on the amount of detected thermal energy. The microbolometer may absorb incident IR radiation and generate a corresponding temperature change within the microbolometer. This temperature change is associated with a corresponding change in the resistance of the microbolometer. Where each microbolometer is used as a pixel, a two-dimensional image or picture representation of the incident IR radiation can be generated by converting the resistance change of each microbolometer into a time-division multiplexed electrical signal. The conversion may be performed by a ROIC. Microbolometers (FPAs) can include IR detection materials such as amorphous silicon (a-Si) and vanadium oxide (VO₂O₃). x ( ), its combination and / or other detection materials. In one aspect, for a microbolometer FPA, the integration time can be or may indicate the time interval during which the microbolometer is biased. In this case, a longer integration time may be associated with a higher gain of the IR signal, but without collecting more IR radiation. IR radiation can be collected by the microbolometer in the form of thermal energy.

[0042] In some cases, the imaging capture component 115 may include one or more filters adapted to allow radiation of certain wavelengths to pass through while substantially blocking radiation of other wavelengths. For example, the imaging capture component 115 may be an IR imaging device that includes one or more filters (e.g., MWIR filters, thermal IR filters, and narrowband filters) adapted to allow IR radiation of certain wavelengths to pass through while substantially blocking IR radiation of other wavelengths. In this example, such filters may be used to customize the imaging capture component 115 to increase sensitivity to desired frequency bands of IR wavelengths. In one aspect, when an IR imaging device is customized for capturing thermal IR images, the IR imaging device may be referred to as a thermal imaging device. Other imaging devices, including IR imaging devices customized for capturing infrared IR images outside the thermal range, may be referred to as non-thermal imaging devices.

[0043] In one particular non-limiting example, the image capture component 115 may include an IR imaging sensor having an FPA that responds to IR radiation including near-infrared (NIR), short-wave IR (SWIR), MWIR, long-wave IR (LWIR), and / or very long-wave IR (VLWIR) radiation. In some other embodiments, alternatively or additionally, the image capture component 115 may include a complementary metal-oxide-semiconductor (CMOS) sensor or a charge-coupled device (CCD) sensor that can be found in any consumer camera (e.g., a visible light camera).

[0044] Other imaging sensors that can be implemented in the image capture unit 115 include photon mixer device (PMD) imaging sensors or other time-of-flight (ToF) imaging sensors, light detection and ranging (LIDAR) imaging devices, millimeter-scale imaging devices, positron emission tomography (PET) scanners, single-photon emission computed tomography (SPECT) scanners, ultrasound imaging devices, or other imaging devices operating in a specific modality and / or spectrum. It is noteworthy that some of these imaging sensors configured to capture images in a specific modality and / or frequency (e.g., infrared spectrum, etc.) are more prone to producing images with low-frequency shadows when compared, for example, to general CMOS-based or CCD-based imaging sensors or other imaging sensors, imaging scanners, or imaging devices of different modalities.

[0045] The image provided by the image capture unit 115, or the corresponding digital image data, can be associated with a corresponding image size (also known as pixel size). Image size or pixel size typically refers to the number of pixels in an image; for example, for a two-dimensional image, it can be represented as width multiplied by height, or otherwise in a way that suits the relevant size or shape of the image. Therefore, an image with its original resolution can be resized to a smaller size (e.g., with a smaller pixel size) to, for example, reduce the cost of processing and analyzing the image. Filters (e.g., non-uniformity estimates) can be generated based on analysis of the resized image. The filter can then be resized to the original resolution and size of the image before being applied to the image.

[0046] In some embodiments, the image interface 120 may include suitable input ports, connectors, switches, and / or circuitry configured to interface with external devices (e.g., remote device 150 and / or other devices) to receive images (e.g., digital image data) generated by or otherwise stored in the external device. The received images or image data may be provided to the processing unit 105. In this regard, the received images or image data may be converted into signals or data suitable for processing by the processing unit 105. For example, in one embodiment, the image interface 120 may be configured to receive analog video data and convert it into suitable digital data for provision to the processing unit 105.

[0047] In some embodiments, the image interface 120 may include various standard video ports that can be connected to a video player, camera, or other device capable of generating standard video signals, and can convert received video signals into digital video / image data suitable for processing by the processing unit 105. In some embodiments, the image interface 120 may also be configured to interface with and receive images (e.g., image data) from the image capture unit 115. In other embodiments, the image capture unit 115 may be directly connected to the processing unit 105.

[0048] In one embodiment, control unit 125 includes user input and / or interface devices adapted to generate user input control signals, such as rotary knobs (e.g., potentiometers), buttons, sliders, keyboards, and / or other devices. Processing unit 105 may be configured to sense control input signals from a user via control unit 125 and respond to any sensed control input signals received therefrom. As those skilled in the art will generally understand, processing unit 105 may be configured to interpret such control input signals as values. In one embodiment, control unit 125 may include a control unit (e.g., a wired or wireless handheld control unit) having buttons adapted to interact with a user and receive user input control values. In one implementation, the buttons on the control unit may be used to control various functions of the imaging system 100, such as autofocus, menu enable and selection, field of view, brightness, contrast, noise filtering, image enhancement, and / or various other functions of the imaging system or camera.

[0049] In one embodiment, display unit 130 includes an image display device (e.g., a liquid crystal display (LCD)) or various other types of well-known video displays or monitors. Processing unit 105 may be configured to display image data and information on display unit 130. Processing unit 105 may be configured to acquire image data and information from memory unit 110 and display any acquired image data and information on display unit 130. Display unit 130 may include display circuitry that may be used by processing unit 105 to display image data and information. Display unit 130 may be adapted to receive image data and information directly from image capture unit 115, processing unit 105, and / or image interface 120, or image data and information may be transmitted from memory unit 110 via processing unit 105.

[0050] In one embodiment, as those skilled in the art will understand, depending on the application or implementation requirements, sensing component 135 may include one or more sensors of different types. The sensors of sensing component 135 provide at least data and / or information to processing component 105. On one hand, processing component 105 may be configured to communicate with sensing component 135. On another hand, sensing component 135 may include a temperature sensor for measuring the temperature of readout circuitry 170 and / or other components of imaging system 100. In various embodiments, sensing component 135 may provide information about environmental conditions, such as external temperature, lighting conditions (e.g., daytime, nighttime, dusk, and / or dawn), humidity levels, specific weather conditions (e.g., sun, rain, and / or snow), distance (e.g., laser rangefinder or time-of-flight camera), and / or whether entry into or exit from a tunnel or other type of enclosure has occurred. Sensing component 135 may represent conventional sensors known to those skilled in the art for monitoring various conditions (e.g., environmental conditions) that may affect (e.g., the appearance of the image) provided by image capture component 115.

[0051] In some embodiments, sensing element 135 (e.g., one or more sensors) may include a device that relays information to processing element 105 via wired and / or wireless communications. For example, sensing element 135 may be adapted to receive information from satellites, via local broadcast (e.g., radio frequency (RF)) transmission, via mobile or cellular networks and / or via information beacons in infrastructure (e.g., traffic or highway information beacon infrastructure), or various other wired and / or wireless technologies. In some embodiments, processing element 105 may use information acquired from sensing element 135 (e.g., sensing data) to modify the configuration of image capture element 115 (e.g., adjust the sensitivity level, adjust the orientation or angle of image capture element 115, adjust the aperture, etc.).

[0052] In some embodiments, various components of the imaging system 100 may be distributed on a network 115 and communicate with each other via a network 155. In this regard, the imaging system 100 may include a network interface 140 configured to facilitate wired and / or wireless communication between the various components of the imaging system 100 via the network 155. In such embodiments, components may also be duplicated for a specific application of the imaging system 100 if desired. That is, components configured for the same or similar operations may be distributed across the network. Furthermore, if desired, all or part of any of the various components may be implemented using suitable components of a remote device 150 (e.g., a conventional digital video recorder (DVR), a computer configured for image processing, and / or other devices) that communicates with the various components of the imaging system 100 via the network 155 and the network interface 140. Thus, for example, all or part of the processing component 105, all or part of the memory component 110, and / or all or part of the display component 130 may be implemented or duplicated at the remote device 150. In some embodiments, the imaging system 100 may not include an imaging sensor (e.g., image capture unit 115), but instead receive images or image data from an imaging sensor located separately and remotely from the processing unit 105 and / or other components of the imaging system 100. It will be understood that many other combinations of distributed implementations of the imaging system 100 are also possible without departing from the scope and spirit of this disclosure.

[0053] Furthermore, in various embodiments, the various components of the imaging system 100 may be combined and / or implemented, or not combined and / or not implemented, as needed or according to application or requirements. In one example, the processing unit 105 may be combined with the memory unit 110, the image capture unit 115, the image interface 120, the display unit 130, the sensing unit 135, and / or the network interface 140. In another example, the processing unit 105 may be combined with the image capture unit 115 such that certain functions of the processing unit 105 are performed by circuitry (e.g., a processor, microprocessor, logic device, microcontroller, etc.) within the image capture unit 115.

[0054] Figure 2 An example calorimeter circuit 200 according to one or more embodiments of the present disclosure is shown. However, not all depicted components are necessary, and one or more embodiments may include additional components not shown in the figures. Variations in the arrangement and type of components may be made without departing from the spirit or scope of the claims set forth herein. Additional components, different components, and / or fewer components may be provided. In one embodiment, the calorimeter circuit 200 may be an FPA, may include an FPA, or may be part of an FPA, for example, implemented as Figure 1The imaging capture unit 115, processing unit 105, sensing unit 135, and / or other components. In one embodiment, the calorimeter circuit 200 may be part of a camera (e.g., a thermal infrared camera).

[0055] The calorimeter circuit 200 includes a plurality of active calorimeters 205, which can be configured to be arranged in an array of rectangular, square, circular, linear, or other shapes. In some non-limiting examples, the active calorimeters 205 can be configured as a rectangular array having dimensions of 80×60 (e.g., 80 rows and 60 columns of unit cells), 160×120, 320×240, 512×512, 1024×1024, 2048×2048, 4096×4096, 8192×8192, or any other size required for a particular application. The calorimeter circuit 200 may include various components and circuitry, collectively referred to as ROIC, which interface with the active calorimeters 205 to generate an output. A calorimeter circuit having an array of active calorimeters and associated circuitry formed together on a substrate (e.g., some embodiments of calorimeter circuit 200) may also be referred to as an FPA.

[0056] Some portions of the ROIC (e.g., switches for a particular calorimeter) can be associated with and placed near each specific effective calorimeter in the effective calorimeters 205. Each of the effective calorimeters 205, together with a portion of its associated ROIC, can also be referred to as a unit cell. Since the effective calorimeters 205 can be configured as an array, the corresponding unit cells can form a unit cell array 210. Additionally, in the context of imaging, each of the effective calorimeters 205 can also be referred to as a pixel. In some embodiments, components of the calorimeter circuit 200 can be implemented on a wafer, wherein the calorimeter array is located (e.g., grown on) a substrate having the ROIC circuitry. In other embodiments, components of the calorimeter circuitry 200 can be implemented as a hybrid wafer arrangement, such that the unit cell array 210 is integrated into (e.g., bonded to, connected to, mated to) the ROIC circuitry. Examples of such integration are related to… Figure 3 Describe it.

[0057] The effective calorimeter 205 may be disposed on the substrate 215, but substantially thermally isolated from the substrate 215 (e.g., released from the substrate 215 such that the effective calorimeter 205 is substantially unaffected by the heat of the substrate 215). The effective calorimeter 205 may be configured to receive IR radiation from an external scene, for example, which is guided onto the effective calorimeter 205 by an optical element such as an IR transmission lens. The IR radiation incident on the effective calorimeter 205 changes the temperature and thus the resistivity of the effective calorimeter 205. The temperature and resistivity of the effective calorimeter 205 may also track the temperature of the substrate 215, but because the effective calorimeter 205 is thermally isolated from the substrate 215, the rate of temperature change due to the substrate 215 is slower than the rate of temperature change due to the incident IR radiation. The ROIC of the calorimeter circuit 200 includes various components and circuits configured to generate an output based on the resistivity change of the effective calorimeter 205 due to the incident IR radiation.

[0058] The calorimeter circuit 200 includes a bias circuit 220 configured to control a bias signal (e.g., bias voltage or current) across the effective calorimeter 205 when generating such an output. Typically, a bias can be applied across the calorimeter to allow measurement of the calorimeter's resistance (or any variation thereof). According to various embodiments of the calorimeter circuit 200, the bias circuit 220 can be used to control the bias applied across the effective calorimeter 205 to an appropriate level so that the nominal value measured by the effective calorimeter can be adjusted to fall within a desired range. In this regard, according to some embodiments, the bias circuit 220 can be configured to set the bias based on calibration data (e.g., adjustment values ​​stored as binary bits) stored in a calibration data memory 225. In other embodiments, such calibration data can be provided to the bias circuit 220 directly or via the calibration data memory 225 from a source external to the calorimeter circuit 200 (e.g., from an external processor and / or memory). In one embodiment, the bias applied by the transmembrane calorimeter may be at least partially based on the bias setting reference signal V. REF In some respects, the bias setting reference signal V REF It can be used to facilitate vacuum health detection of the radiation calorimeter circuit 200.

[0059] In some embodiments, bias circuit 220 may be configured to globally bias all valid calorimeters 205. In other embodiments, bias circuit 220 may be configured to provide a specific bias level for each individual valid calorimeter or group of valid calorimeters 205. In yet another embodiment, bias circuit 220 may be configured to set a global bias level for all valid calorimeters 205 and apply adjustments specific to each valid calorimeter or group of valid calorimeters 205.

[0060] Each unit cell in unit cell array 210 can receive a bias signal (e.g., bias voltage, bias current) to bias the unit cell's detector, thereby compensating for different response characteristics attributable to factors such as temperature variations, manufacturing differences, and / or other factors. For example, bias circuitry 220 can generate bias signals and provide them to the unit cells. By providing an appropriate bias signal to each unit cell, unit cell array 210 can be effectively calibrated to provide accurate image data in response to light (e.g., IR light) incident on the detector of the unit cell.

[0061] The calorimeter circuit 200 includes effective calorimeters 205 arranged in an array or other configuration. According to one or more embodiments of the calorimeter circuit 200, circuitry and interconnections can be reduced by appropriately multiplexing the effective calorimeters 205 to various components of the ROIC. For example, in one embodiment, instead of replicating similar circuitry for each row 230 of the unit cell array 210, rows 230 can be multiplexed to column circuitry 235, including common components 240 to 252 that can be time-multiplexed for all rows 230. Column circuitry 235 can typically represent any column processing circuitry suitable for a given application (analog and / or digital) (e.g., signal amplification and signal filtering). Signals received by column circuitry 235, such as analog signals on an analog bus and / or digital signals on a digital bus, can be processed according to the analog or digital nature of the signal. As a non-limiting example, in Figure 2 In one or more embodiments, the components of the column circuit 235 may include a load calorimeter 240, an amplifier 242, a feedback resistor 244, a low-pass filter (LPF) 246, a sample-and-hold circuit 248, a comparator 250, a latch 252 and / or other components.

[0062] exist Figure 2In the example shown, each column of the unit cell array 210 has a corresponding unit cell in the column circuit 235, such that the unit cells of all rows in a single column can be multiplexed to a single corresponding column circuit. The column circuit 235 can then be multiplexed by the column multiplexer 255 to generate, for example, combined outputs of the unit cell array 210 in a multiplexed manner. It should be noted that the number of column circuits can be set to be greater than or less than the number of columns in the unit cell array 210. It should also be noted that the unit cell array 210 may include appropriate ROIC components to generate outputs without multiplexing. It should be noted that the terms "column" and "row" are used herein for ease of illustration only and are therefore used interchangeably depending on the described structure.

[0063] In one or more embodiments, the calorimeter circuit 200 includes timing and control circuitry 260 configured to generate control signals for multiplexing the effective calorimeter 230 and column circuitry 235. For example, the timing and control circuitry 260 may be configured to control switches associated with the effective calorimeter 205 and column circuitry 235 to selectively connect the effective calorimeter 205 to the appropriate column circuitry 235 according to a specified timing, thereby achieving timing multiplexing of the effective calorimeter 205 to the column circuitry 235. In this regard, the timing and control circuitry 260 may generate control signals for addressing the unit cell array 210 (e.g., to turn switches on or off) to allow access to and read image data from the addressed portion of the unit cell array 210. For illustrative purposes, the unit cell array 210 may be addressed to access and read image data row by row from the unit cell array 210; however, in other embodiments, the unit cell array 210 may be addressed column by column or otherwise. In some embodiments, the timing and control circuit 260 may also be configured to provide timing control over other components of the calorimeter circuit 100. For example, portions of the bias circuit 220, blind calorimeter units, or other components may be selectively enabled and / or connected in conjunction with multiplexing of the active calorimeter 205 via control signals generated by the timing and control circuit 260 according to appropriate timing. In another example, in response to control signals from the timing and control circuit 260, calibration data (e.g., adjustment bits stored in calibration data memory 225) or other data may be provided (e.g., transferred, transferred, and / or latched) to appropriate components of the calorimeter circuit 200 (e.g., the bias circuit 220) according to specified timing.

[0064] The calorimeter circuit 200 includes a blind calorimeter 275. The blind calorimeter 275 is thermally isolated from (e.g., released from) the substrate 215, similar to the effective calorimeter 205. However, unlike the effective calorimeter 205, the blind calorimeter 275 is shielded from IR radiation from an external scene. For example, one or more structures (e.g., a cover, shutter, shroud) can prevent the blind calorimeter 275 from seeing the scene incident on the unit cell array 210. This structure can be positioned above the blind calorimeter 275 (e.g., fabricated on top of the blind calorimeter 275) to block (e.g., shield) the scene from reaching the blind calorimeter 275. The signal output of the blind calorimeter 275 is based on ambient temperature and can be considered independent of the scene. The blind calorimeter 275 can capture the value (e.g., absolute value) of the temperature pedestal incident on both the effective calorimeter 205 and the blind calorimeter 275.

[0065] Therefore, the blind calorimeter 275 does not substantially change its temperature in response to the level of incident radiation from the external scene, but its temperature changes due to self-heating (e.g., pulsed bias heating) and temperature variations in the substrate 215. In some cases, since the effective calorimeter 205 and the blind calorimeter 275 change to their first-order tracking temperatures due to self-heating and substrate temperature variations, the blind calorimeter 275 can be configured as a reference for adjusting the bias of the effective calorimeter 205. Each of the blind calorimeters 275, together with its associated circuitry (e.g., associated switches and structures or portions thereof), may be referred to as a blind calorimeter unit, a reference calorimeter unit, a blind unit unit, or a reference unit unit.

[0066] For example, unit cell array 230 may include 2048 × 2048 effective unit cells and 2048 × 20 reference unit cells located near the FPA. The reference unit cells may be located among, around, along the sides of, or substantially relative to the effective unit cells, such that the ambient temperature experienced by the reference unit cells is equal to or substantially equal to the ambient temperature experienced by the effective unit cells. In some cases, the reference unit cells may be in the same row and / or column as the effective unit cells. In some cases, the reference unit cells may be additional rows adjacent to the effective unit cells, such as... Figure 2 As shown. In some cases, a reference unit cell may be an additional column adjacent to a valid unit cell. In some cases, at least one of the reference unit cells may not share rows and / or columns with any valid unit cells. In various embodiments, addressing of the unit cell array 210 generally does not depend on whether the addressed line includes only valid unit cells, only reference unit cells, or both valid unit cells and reference unit cells.

[0067] According to some embodiments, the calorimeter circuit 200 includes a ramp generator 265. The ramp generator 265 can be configured to generate a ramp signal for performing a ramp comparison analog-to-digital (A / D) conversion in the calorimeter circuit 200 or for other purposes (e.g., as a reference signal for detecting clock rates). In other embodiments of the calorimeter circuit 200, such as embodiments that do not include A / D conversion circuitry, the ramp generator 265 may be omitted from the calorimeter circuit 200. For example, according to some embodiments, the A / D conversion circuitry and the ramp generator may be external to the calorimeter circuit 200.

[0068] According to some embodiments, the calorimeter circuit 200 includes a temperature sensor 270 configured to detect the ambient temperature associated with the substrate 215 of the calorimeter circuit 200. In some embodiments, the temperature sensor 270 may be disposed on the substrate 215 adjacent to the active calorimeter 205 and / or the blind calorimeter 275, such that the temperature readings obtained by the temperature sensor 270 can closely track the substrate temperature affecting these components. In some embodiments, the calorimeter circuit 200 may be configured to output a substrate temperature reading based on the temperature detected by the temperature sensor 270, such that the substrate temperature reading can be accessed by a component external to the calorimeter circuit 200 (e.g., a processor external to the calorimeter circuit 200). For example, such a substrate temperature reading can be used to perform various corrections (e.g., non-uniformity correction) and calibration processes via a processor or other logic device.

[0069] Temperature readings (e.g., substrate temperature readings) obtained by temperature sensor 270 can be used, for example, to obtain and apply calibration data within a certain temperature range (e.g., substrate temperature). In some cases, the calibration data may include data used to facilitate vacuum health detection (e.g., vacuum loss detection), such as values ​​associated with reference signals for various temperatures within the operating temperature range of the calorimeter circuit 200. For a given temperature (e.g., provided by temperature sensor 270), the deviation of the value associated with the reference signal from the expected value at that given temperature, determined during calibration (e.g., at the factory) and stored as calibration data (e.g., in calibration data memory 225), can indicate a possible vacuum loss.

[0070] In some embodiments, the calorimeter circuit 200 includes a processor or other logic device 280 configured to perform various operations associated with the calorimeter circuit 200 based on configuration data stored in configuration data memory 225. For example, in one embodiment, the processor or other logic device 280 may be configured to perform at least a portion of the various processes discussed herein. For example, for a given temperature (e.g., measured by temperature sensor 270), the processor or other logic device 280 may determine vacuum health based on a value associated with a reference signal (e.g., a digital count representing the value associated with the reference signal) and an expected value associated with such a signal. In other embodiments, other external components (e.g., the processor of a host device) or internal components (e.g., timing and control circuitry 260) may be additionally or alternatively configured to perform at least a portion of the various processes disclosed herein.

[0071] According to one or more embodiments, the processor or other logic device 280 can be implemented using any suitable combination of processing devices, such as a general-purpose CPU, a PLD including an FPGA, a hard-wired ASIC, a DSP, an image signal processor (ISP), or other logic devices that can perform processing operations by executing instructions provided from configuration data memory 285 and / or by configuring logic circuitry according to configuration data (e.g., FPGA configuration data) provided from configuration data memory 285. In one aspect, the output signal provided by the unit cell array 230 and read by the ROIC can be an image formed from the pixel values ​​of the unit cells from the unit cell array 230. The processor or other logic device 280 can perform operations such as NUC, spatial and / or temporal filtering, and / or other operations. The image (e.g., a processed image) can be stored in memory (e.g., external to or local to the imaging system) and / or displayed on a display device (e.g., external to and / or integrated with the imaging system).

[0072] As discussed, Figure 2 This is a block diagram that helps to describe and explain the radiation calorimeter circuit 200 and its various components according to one or more embodiments of this disclosure. Therefore, Figure 2 The block diagram is not intended to limit the size, number, placement, or orientation of the various components shown therein. For example, although blind calorimeters are... Figure 2 The rows of blind calorimeters 275 above the unit cell array 210 are represented in the diagram. However, according to various embodiments, depending on the specific implementation of the calorimeter circuit 200, some or all of the blind calorimeters represented by the blind calorimeters 275 may be configured as one or more columns of blind calorimeters adjacent to the columns of the unit cell array 210 (to implement blind calorimeters for bias columns).

[0073] In one embodiment, the calorimeter circuit 200 can be implemented as part of an imaging system (e.g., 100). In addition to the various components of the calorimeter circuit 200, the imaging system may also include one or more processors, memories, logic devices, displays, interfaces, optics (e.g., lenses, mirrors, beam splitters), and / or other components suitable for various implementations. Note that... Figure 2 The various components can be implemented on a single chip or multiple chips. Furthermore, although the various components are shown as a set of separate boxes, these boxes can be combined together or... Figure 2 The various boxes shown can be divided into individual boxes.

[0074] The calorimeter circuit 200 can be implemented using a single wafer, wherein the calorimeter array may be located (e.g., grown on) a ROIC in various embodiments, or in other embodiments, hybrid circuitry or other circuitry may be used on a second wafer. In an exemplary embodiment using multiple wafers, components of the calorimeter circuit 200 may be implemented such that the detector array is hybridized (e.g., bonded to) a readout circuit. For example, Figure 3 An example calorimeter circuit 300 according to one or more embodiments of the present disclosure is shown. However, not all depicted components are necessary, and one or more embodiments may include additional components not shown in the figures. Variations in the arrangement and type of components may be made without departing from the spirit or scope of the claims set forth herein. Additional components, different components, and / or fewer components may be provided. In one embodiment, calorimeter circuit 300 may be calorimeter circuit 200, may include calorimeter circuit 200, or may be a part of calorimeter circuit 200.

[0075] The calorimeter circuit 300 includes a device wafer 305, a readout circuit 310, and contacts 315 to join (e.g., mechanical and electrical) the device wafer 305 to the readout circuit 310. The device wafer 305 may include a detector (e.g., a unit cell array 210). The contacts 315 may engage the detector of the device wafer 305 and the readout circuit 310. The contacts 315 may include conductive contacts of the detector of the device wafer 305, conductive contacts of the readout circuit 310, and / or a metallic connection between the conductive contacts of the detector and the conductive contacts of the readout circuit 310. In one embodiment, the device wafer 305 may be joined to the readout circuit 310 using bonding bumps (e.g., indium bumps). Bonding bumps may be formed on the device wafer 305 and / or the readout circuit 310 to allow connection between the device wafer 305 and the readout circuit 310. In one aspect, integrating device wafer 305 into readout circuit 310 may involve bonding device wafer 305 (e.g., a detector of device wafer 305) to readout circuit 310 to mechanically and electrically bond device wafer 305 and readout circuit 310.

[0076] In various aspects, the FPA formed by the detector array (e.g., an effective calorimeter array), the blind calorimeter array, and the ROIC can be housed within a vacuum package to provide a high vacuum environment conducive to achieving the desired sensitivity of the detector array. Vacuum integrity may decrease over time due to various factors, such as degassing and / or leakage. For example, when the vacuum is lost, air and / or other gases may enter the sensor cavity and adversely affect the thermal insulation of the detector. Such a reduction in vacuum integrity leads to a gradual loss of vacuum pressure and thus reduces the sensitivity and overall performance of the FPA. The reference detector of the FPA is shielded from incident or external radiation and, similar to the effective detector, is substantially thermally isolated from the ROIC substrate. The effective detector and the reference detector can share various properties, such as operating within the same vacuum cavity and sharing noise properties (e.g., time noise properties).

[0077] In one or more embodiments, the imaging system includes active elements of a detector array and blind elements operating within the same vacuum cavity. For illustrative purposes, the active element includes an active calorimeter and the blind element includes a blind calorimeter, but other suitable types of IR detectors may be used. A reference signal V is generated by the blind calorimeter. REF It can be used to enhance detector arrays (e.g., Figure 2 Vacuum health detection of the unit array 210. On one hand, the reference signal V REF This can be referred to as a bias setting reference signal or a bias column signal (e.g., when the detector array is addressed row by row). A blind cell can be a bias circuit (e.g., Figure 2 It is part of the bias circuit 220. Reference signal VREF It can be used to compensate for the self-heating of an effective calorimeter (e.g., pulse bias heating). On one hand, the reference signal V... REF This can be referred to as the reverse slope voltage.

[0078] Using various embodiments, the reference signal V for each line can be saved / stored. REF The value of V determines the quality of the vacuum. For example, when reading out a detector array line by line, the lines can point to rows. In some cases, a reference signal V is saved at the end of the line (e.g., when all other samples from the valid detectors of that line have been acquired / read out). REF The value of the reference signal V. REF Typically, the greatest variation occurs at the end of the line because the calorimeter remains on throughout the line time. Line time (e.g., also referred to as the line-addressed time period) can refer to the time period associated with a line (e.g., row or column, depending on the implementation) of the addressing unit cell array 210. When the unit cell array 210 is read out row by row, the line time can be referred to as the row time.

[0079] In some cases, the reference signal V REF It can be buffered and provided to the effective pixels of the detector array. For example, the reference signal V REF It can be provided to all columns of the detector array. Reference signal V REF It can have different slopes at temperatures (e.g., ambient temperature). On the one hand, hotter temperatures are associated with higher pulse bias heating and therefore with a larger slope. When the vacuum in which the FPA and the calorimeter are located has a high mass, the reference signal V... REF It has a large slope because the pulse bias heating does not decrease due to thermal shunting of the air. As the vacuum decreases, the reference signal V buffered to the detector array... REF The slope flattens out. In this respect, as the vacuum decreases, pixels may become thermally diverted to the air temperature around them, resulting in a decrease in the pixel's responsiveness to the scene.

[0080] During calibration (e.g., in the factory), due to the reference signal V REF The final value will vary not only with vacuum but also with temperature. Therefore, under high-quality vacuum conditions, a reference signal V for the temperature within the operating temperature range of the thermal radiation calorimeter can be determined and preserved. REF The value of the reference signal V. REF Such a value can be called the expected reference signal value or the calibration reference signal value. For example, lookup tables, equations, and / or other data structures / relationships can be used to store and / or calculate the reference signal V for the temperature within the operating temperature range. REF The value (e.g., in calibration data memory 225).

[0081] In the field, for a blind calorimeter at a given temperature (e.g., the ambient temperature measured by temperature sensor 270), if the reference signal V generated by the blind detector... REF If the value deviates from the expected reference signal value at that temperature by more than a threshold amount, it can be determined that the vacuum in which the blind and active calorimeters of the detector array operate has been significantly reduced. This threshold amount can be selected based on application (e.g., requirements associated with image data integrity), cost considerations, etc. This threshold amount can be characterized by the vacuum level (e.g., amount of vacuum loss), thermal transconductance, and / or other characteristics associated with the vacuum of the calorimeter circuit 200. In some respects, changes in vacuum (e.g., loss) can be associated with changes in thermal transconductance (e.g., increase). As an example, this threshold amount can be associated with a 10% vacuum loss. In some cases, when such a deviation is detected, the imaging system electronics flags a warning to the imaging equipment and / or user that the detector array may experience performance degradation due to vacuum loss / reduction (e.g., the image data generated by the detector array may deteriorate). As a non-limiting example, mitigation actions may include adjusting the processing performed by the imaging system (e.g., the processor or other logic device 280 of the imaging system) due to loss of vacuum, resetting the imaging system (or a portion thereof) to determine whether the error is transient, cycling the power supply associated with the imaging system (or a portion thereof) to determine whether the error is transient, or replacing the imaging system (e.g., replacing the camera containing the imaging system with a different camera).

[0082] If the reference signal V generated by the blind calorimeter REF If the value deviates from the expected reference signal value at that temperature within a threshold amount, it can be determined that the vacuum has not decreased significantly (e.g., not to the extent that it requires the attention of the user or imaging system), but the deviation can be stored and / or reported (e.g., to the imaging system electronics and / or the user) for monitoring purposes.

[0083] Figure 4 An example system 400 for facilitating vacuum health detection according to one or more embodiments of the present disclosure is shown. However, not all depicted components are necessary, and one or more embodiments may include additional components not shown in the figures. Variations in the arrangement and type of components may be made without departing from the spirit or scope of the claims set forth herein. Additional components, different components, and / or fewer components may be provided.

[0084] System 400 includes a blind calorimeter 405, a buffer circuit 410, an A / D converter 415, and a vacuum health monitoring device 420. The blind calorimeter 405 generates a reference signal V. REFThe buffer circuit 410 (e.g., a sample-and-hold circuit) stores (e.g., temporarily stores, buffers, holds, saves) the reference signal V. REF In one case, the buffer circuit 110 provides V for each line. REF The value is sampled and buffered. For example, the reference signal V REF The value can be sampled around the end of the online time. In one aspect, the buffer circuit 410 may include one or more buffer amplifiers, one or more multiplexers, and / or one or more sample-and-hold circuits. The buffer amplifiers, multiplexers, and / or sample-and-hold circuits can be suitably arranged to facilitate interaction with the reference signal V. REF The value is associated with the timing of the readout relative to the effective calorimeter reading. A multiplexer may be optional. In some cases, the buffer circuit 410 does not alter the reference signal V generated by the blind calorimeter 405. REF In other cases, the buffer circuit 410 can perform processing (e.g., level shifting and / or other processing) to adjust the reference signal V. REF The value of .

[0085] A / D converter 415 receives reference signal V from buffer circuit 410. REF The A / D converter 415 may include a ramp generator that generates a ramp signal and a comparator that receives the ramp signal from the ramp generator and compares it with a reference signal V from the buffer circuit 410. REF A comparison is made to provide a digital count value as a reference signal V. REF The value is represented by a number.

[0086] Vacuum health monitoring device 420 receives digital count values ​​from A / D converter 415 and temperature T associated with blind calorimeter 405. sub (For example, measured by a temperature sensor of or connected to system 400). On one hand, temperature T... sub This can be the temperature of the ROIC associated with system 400 (e.g., also known as ambient temperature or substrate temperature). Vacuum health monitoring device 420 is based on digital count values ​​and temperature T. subThe expected digital count value determines vacuum health. For example, vacuum health detection device 420 can determine (e.g., calculate) the deviation between this digital count value and the expected digital count value to determine whether the vacuum loss associated with the blind calorimeter 405 exceeds a threshold amount (e.g., 10% vacuum loss). In some cases, vacuum health detection device 420 can output an indication of vacuum health. As an example, vacuum health detection device 420 can provide an indication only when a possible fault condition is detected (e.g., vacuum loss exceeds a threshold). As another example, vacuum health detection device 420 can provide an indication both when a possible fault condition is detected and when no fault condition is detected. In some embodiments, A / D converter 415 is optional, such that the reference signal V REF The value is an analog signal, which is directly used by the vacuum health detection device 420 to compare with the expected value to determine vacuum health.

[0087] Figure 5 A flowchart illustrating an example process 500 for facilitating vacuum health detection (e.g., vacuum loss detection) according to one or more embodiments of the present disclosure is shown. For illustrative purposes, reference is made primarily herein to... Figure 4 The process 500 is described using system 400. However, process 500 can be performed with respect to other systems used to facilitate vacuum health detection. Note that... Figure 5 One or more operations can be combined, omitted, and / or performed in different orders as needed.

[0088] At frame 505, the blind calorimeter 405 generates a reference signal V. REF At box 510, buffer circuit 410 stores (e.g., buffers, holds, saves) the reference signal V. REF In this respect, the buffer circuit 410 can buffer the reference signal V. REF Sampling is performed to obtain the reference signal V. REF The sampled value. On the one hand, the buffer circuit 410 can adjust the reference signal V around the end of the online time. REF Sampling is performed. The end of the line time can be the latter half of the line time, the last 30% of the line time, the last 20% of the line time, the last 10% of the line time, the last 5% of the line time, the last 2% of the line time, the last 1% of the line time, any time in between, or less than the last 1% of the line time. In some cases, the buffer circuit 410 does not change the reference signal V generated by the blind calorimeter 405. REF In other cases, the buffer circuit 410 can perform processing (e.g., level shifting and / or other processing) to adjust the reference signal V. REF The value. At box 515, the vacuum health monitoring device 420 is based on the reference signal V. REFVacuum health is determined using a pre-defined reference signal. In one aspect, the temperature associated with the blind calorimeter 405 can be determined (e.g., via temperature sensor 270), and the pre-defined reference signal associated with that temperature can be used by the vacuum health detection device 420. REF The difference between the buffered reference signal and the expected reference signal is used to determine vacuum health. In some cases, the A / D converter can convert the buffered reference signal into a digital count value, and the vacuum health detection device 420 can determine the difference between this digital count value and the expected digital count value.

[0089] At box 520, vacuum health detection device 420 determines whether a vacuum can be considered healthy. In some cases, vacuum health detection device 420 can determine this by using a reference signal V. REF The difference between the expected reference signal and the threshold signal is compared to determine whether the vacuum can be considered healthy. For example, a difference exceeding the threshold may indicate a vacuum loss of more than 10%. If the difference is higher than the threshold (e.g., the difference indicates a vacuum loss of 10% or more), the vacuum can be considered unhealthy. If it is determined at block 520 that the vacuum can be considered healthy, process 500 proceeds to block 505 to induce the generation of a reference signal (e.g., for the next line of unit cell array 210).

[0090] If it is determined at box 520 that the vacuum is not considered healthy, process 500 proceeds to box 525. At box 525, the vacuum health detection device 420 sends an error status (e.g., to facilitate mitigation actions and / or further analysis by the user and / or the imaging system, including the blind calorimeter 405). In some cases, even when a potential vacuum loss is detected and an error status is sent (e.g., at box 525), the imaging system may continue to operate to capture image data and process 500 may return to box 505 to generate a reference signal (e.g., for the next frame or the next line of the frame).

[0091] Although Figure 5 An example using a single threshold is shown, but in some embodiments, multiple thresholds can be used. For example, when the reference signal V... REFWhen the difference between the expected reference signal and the actual vacuum loss is less than 10%, no error status is sent. When the difference indicates a vacuum loss between 10% and 15%, an error status is sent, indicating the estimated vacuum loss for monitoring purposes, but the imaging system does not perform any further actions without user intervention. When the difference indicates a vacuum loss exceeding 15%, an error status is sent, indicating the estimated vacuum loss and suggesting mitigation actions for the user. Multiple thresholds and values ​​associated with each threshold can be defined by the user, the imaging system manufacturer (e.g., based on general imaging application requirements), the imaging system deployment manager (e.g., as part of a larger surveillance application), and / or other parties.

[0092] As a non-limiting example, mitigation actions may include adjusting the processing performed by the imaging system due to vacuum loss, resetting the imaging system (or a portion thereof) to determine if the error is transient, cycling the power supply associated with the imaging system (or a portion thereof) to determine if the error is transient, or replacing the imaging system (e.g., replacing the camera containing the imaging system with a different camera). For example, vacuum health monitoring device 420 may send the error status to other components of the imaging system, such as a processor or other logic device 280. This processor or other logic device 280 may process the image data captured by the effective calorimeter to mitigate the degradation that may be associated with vacuum loss.

[0093] Figure 6 An example bias circuit 600 for facilitating vacuum detection (e.g., vacuum loss detection) according to one or more embodiments of the present disclosure is shown. However, not all depicted components are necessary, and one or more embodiments may include additional components not shown in the figures. Changes in the arrangement and type of components may be made without departing from the spirit or scope of the claims set forth herein. Additional components, different components, and / or fewer components may be provided. In one embodiment, bias circuit 220 and column circuit 235, or portions thereof, may jointly implement bias circuit 600 or portions thereof. Bias circuit 600 may represent an example implementation of a portion of calorimeter circuit 200.

[0094] The bias circuit 600 includes a bias column (e.g., bias column 605), a buffer circuit 610, an A / D converter 615, and a multiplexer 620. Figure 6 In this context, bias column 605 is one of N bias columns. Other bias columns may include components similar to those shown in bias column 605. Bias column 605 provides (e.g., in...) Figure 6 At the node marked BCOL, the voltage level V changes in response to the self-heating of the blind calorimeter 625, which tracks the effective calorimeter. REF ( Figure 6(Not shown in the image). The blind calorimeter 625 is thermally isolated from the substrate (e.g., from it) and is substantially shielded from incident IR radiation, so the temperature of the blind calorimeter 625 changes due to self-heating and substrate temperature variations but not due to incident IR radiation. In some cases, the blind calorimeter 625 can be implemented to exhibit a similar temperature coefficient of resistance (TCR) and resistance value as an effective calorimeter.

[0095] The bias column 605 includes a thermally short-circuited calorimeter 630, which can act as a temperature-compensated load. The thermally short-circuited calorimeter 630 can be connected in series with a blind calorimeter 625 in a conduction path. In one aspect, the conduction path extends from the power supply voltage node to the common voltage node and mirrors the conduction path including both a thermally short-circuited calorimeter for measuring incident IR radiation and an effective calorimeter. Due to this mirroring of the effective calorimeter with a blind calorimeter that tracks the resistance change at the effective calorimeter due to self-heating, the bias column 605 can act as a voltage divider, providing an indication bias setting reference voltage V. REF The voltage level of the change should be such that (e.g., when obtained from a node labeled BCOL) so that the output associated with the effective calorimeter primarily represents the incident IR radiation from the scene attributable to the temperature change at the effective calorimeter. Switches 650A-C are configured for the blind calorimeter 625 and are selectively closed or opened according to appropriate timing based on signals from timing and control circuitry (e.g., timing and control circuitry 260). Each of switches 650A-C can be appropriately closed or opened to selectively enable the blind calorimeter 625 to track the self-heating of the corresponding effective calorimeter.

[0096] Node BCOL of bias column 605 is connected to buffer 640. In some cases, buffer 640 can receive voltage V. REF And the output voltage V REF In other cases, buffer 640 can adjust voltage V in response to a bias adjustment bit. REF It outputs an adjusted voltage. The bias adjustment bits can be used to perform global fine-tuning of the varying self-heating compensation voltage level provided by the bias column 605. For example, the bias adjustment bits can be stored in the calibration data memory. For illustrative purposes, the output of buffer 640 is referred to as voltage V. REF In one aspect, by using multiple bias columns, the voltage levels at the corresponding BCOL nodes can be averaged to provide an average reference voltage V to the buffer 640. REF Average reference voltage V REFThis can later be used as a basis for detecting vacuum loss associated with blind calorimeter 625 and / or other blind calorimeters. In one aspect, buffer 640 can be used to drive the signal at the BCOL node to a large capacitive load, because the reference signal V... REF Reach all columns. Since the sample-and-hold circuit 670 and the A / D converter 615 are among these columns and the reference signal V... REF The column has been reached, therefore the reference signal V can be used on BCOL. REF .

[0097] The output of buffer 640 is provided to the IN2 input of multiplexer 665 to allow the voltage stored in sample-and-hold circuit 670 to become either the output of buffer 640 or a signal provided to the IN1 input of multiplexer 665. The output of multiplexer 665 is connected to sample-and-hold circuit 670. Multiplexer 665 and sample-and-hold circuit 670 can be operated to store voltage V for a duration controlled by signals from timing and control circuitry. REF (For example, as the output of buffer 640). Such timing control can facilitate the operation of the reference signal V. REF The value is associated with the timing of the readout relative to the effective calorimeter reading. In one case, the output of buffer 640 can also be provided to other circuits. Figure 6 (Not shown in the image), for example, a circuit that generates a bias signal for an effective calorimeter.

[0098] Multiplexer 665 allows A / D converter 615 to be shared with other circuits (e.g., time multiplexing). As an example, in a first mode, multiplexer 665 can be used to route the output of buffer 640 received through its IN2 input to sample-and-hold circuit 670 to facilitate vacuum health determination / detection. In a second mode, multiplexer 665 can be used to route the output of buffer 640 received through its IN1 input from other circuits (… Figure 6 The received signal (not shown) is routed to the sample-and-hold circuit 670 (e.g., for other purposes). In some aspects, such as when the A / D converter 615 is dedicated to facilitating vacuum health determination / detection, the multiplexer 665 is optional. In some aspects, more than one multiplexer can be used (e.g., to selectively provide one of multiple signals to the sample-and-hold circuit 670). In some cases, multiplexers can be used so that various components can be shared by a fewer number of A / D converters (e.g., compared to an imaging system implemented with fewer multiplexers and more A / D converters). In some aspects, the buffer 640 and / or the multiplexer 665 can be optional. In some cases, the reference signal V... REFThe sample-and-hold circuit 670 is supplied directly from the BCOL node (e.g., without intermediate buffer amplifiers or multiplexers).

[0099] The voltage V held by the sample-and-hold circuit 670 REF The value is provided to the input of comparator 675 of A / D converter 615. Ramp generator 680 of A / D converter 615 generates a ramp signal (e.g., a ramp voltage). The ramp signal can be a signal that rises linearly or falls linearly with respect to time. In some cases, the ramp signal can be a sawtooth signal that begins at a minimum value around the start of the online time and ends at a maximum value around the end of the online time. Level shift buffer 685 may be optional and can be used to level shift the ramp signal. In some cases, ramp generator 680 and level shift buffer 685 may be collectively referred to as a ramp generator. The output of level shift buffer 685 is provided to the input of comparator 675.

[0100] In some respects, such as Figure 6 As shown, the sample-and-hold circuit 670 can be implemented as two sample-and-hold components, each including two switches and a shunt capacitor. The first sample-and-hold component includes switches SHO and CMPENO and a shunt capacitor Csh. The second sample-and-hold component includes switches SHE and CMPENE and a shunt capacitor Csh. In one example, consider a unit cell array having at least rows 1 to 3, where the unit cell array is read row by row starting from row 1. During the first line time, the reference voltage V associated with row 1... REF The value can be driven into the first sample-and-hold component. During the second line time, the voltage reference V associated with the second line... REF The value can be driven to the second sample-and-hold component. When V associated with row 2... REF When the value is driven into the second sample-and-hold unit, the V associated with the first row REF The value can be provided from the first sample-and-hold unit to the A / D converter 615. During the third line time, the voltage reference V associated with the third line... REF The value can be driven into the first sample-and-hold component. When V associated with row 3... REF When the value is driven to the first sample-and-hold component, the V associated with the second row REF The value can be provided to the A / D converter 615 from the second sample-and-hold component. Note that the sample-and-hold circuit 670 can be used with... Figure 6 The implementations shown are different. As an example, in other respects, the sample-and-hold circuit can be implemented with a pair of switches and a shunt capacitor. As another example, the sample-and-hold circuit can be implemented with more than two pairs of switches and more than two shunt capacitors.

[0101] Comparator 675 generates an indication of the voltage V provided by sample-and-hold circuit 670. REF Is the value nominally equal to (e.g., substantially equal to, slightly higher than) the output of the level shift buffer 685? When the voltage V supplied by the sample-and-hold circuit 670... REF When the nominal value is equal to the output of the level shift buffer 685, the comparator 675 can be said to be triggered. The output of the comparator 670 is the voltage V. REF The value and the intersection of the output of the level shift buffer 685. The counter circuit 690 adjusts (e.g., increments or decrements, depending on the implementation) the count value (e.g., encoded in one or more count signals) in response to a received clock signal. The count value adjusted by the counter circuit 690 may have a period substantially similar to the ramp signal generated by the ramp generator 680 (e.g., substantially simultaneously reset to zero or the base value). Figure 6 In this circuit, M bits are used to represent the count value. When comparator 675 is triggered, the count value of counter circuit 690 is selected and stored in latch 695. Latch 695 provides the latched count value to multiplexer 620. Multiplexer 620 multiplexes the digital value (e.g., digital bits) stored in latch 695 to generate digital output signal 660. Digital output signal 660 is the voltage V provided by sample-and-hold circuit 670. REF The digital output signal 660 can be provided to processing circuitry downstream of the bias circuit 600, such as processing circuitry used to determine vacuum health based on the digital output signal 660 and the expected digital signal.

[0102] Figure 7 A graph 700 shows the ramp voltage associated with the ramp generator and the digital count value associated with the counter circuit as a function of time. For example, the ramp voltage can be generated by... Figure 2 ramp generator 265 and / or Figure 6 The ramp generator 680 generates, and / or the digital count value can be generated by... Figure 6 The counter circuit 690 is implemented. At time t = t0, the ramp voltage and digital count value can be at the corresponding levels. Figure 7 In this configuration, the ramp voltage and digital count value are displayed as zero at time t = t0. In other cases, the ramp voltage and / or digital count value may be at a corresponding predetermined value (e.g., a predetermined non-zero value) at time t = t0. The digital count value increments over time. Synchronous with the incrementing digital count value, the ramp voltage begins to ramp up over time (e.g., increases linearly).

[0103] At time t = t0 + t1, when the ramp voltage is equal to (e.g., approximately equal to, slightly higher than) the reference signal V REF At that time, the comparator (e.g., Figure 6The comparator 675 changes its comparator output voltage (e.g., from high to low or from low to high, depending on the implementation). The change in the comparator output voltage causes the counter circuit to store a digital count value at or around the change time. At this point, the digital count value N provided by the counter circuit is stored at or around the time of the comparator output voltage change. count It is stored. On one hand, memory elements may include latches or flip-flops that use a clock to capture digital count values. For example, a latch may be... Figure 6 The latch 695.

[0104] Figure 8 A graph 800 shows the relationship between temperature over time and thermal transconductance at different ambient temperatures according to one or more embodiments of the present disclosure. The top curve 805 is related to the thermal transconductance G. th Correlation, bottom curve 810 and thermal transconductance 1.1G th Correlation (e.g., 10% higher thermal transconductance than associated with top curve 805). Top curve 815 and thermal transconductance G th The correlation and bottom curve 820 are related to the thermal transconductance of 1.1G. th Correlation. Compared to the calorimeters characterized by curves 815 and 820, curves 805 and 810 can characterize calorimeters correlated with higher ambient temperatures. Figure 8 The report also provides other unlabeled curves relating to other ambient temperatures. Generally, a lower vacuum is associated with higher thermal transconductance. In some cases, the reference voltage signal V... REF It can be measured at the end of the time interval towards the line. For example... Figure 8 As shown, due to the difference in thermal transconductance, there are temperature differences between the top curve 805 and the bottom curve 810, and between the top curve 815 and the bottom curve 820.

[0105] Figure 9 A graph 900 shows the relationship between a temperature-varying reference voltage signal and thermal transconductance according to one or more embodiments of the present disclosure. The bottom curve 905 and the top curve 910 represent the relationship for thermal transconductance G, respectively. th and 1.1G th The reference voltage signal varies with temperature. Within the ambient / ROIC temperature range (e.g., the range from cold operation to hot operation), there is a difference in the reference voltage signal between the bottom curve 905 and the top curve 910. Figure 10 Two different thermal transconductances (e.g., G) varying with frame number according to one or more embodiments of this disclosure are shown. th and 1.1G thGraph 1000 shows the relationship between the difference in the reference voltage signal and temperature. Curves 1005, 1010, 1015, 1020, and 1025 are associated with temperatures ranging from cold to warm operation, and these curves are ordered / labeled from the lowest temperature of curve 1005 to the highest temperature of curve 1025. After several frames (e.g., several time constants), the difference between the reference voltage signals stabilizes at a certain voltage level.

[0106] Figure 11 An example calorimeter circuit 200 according to one or more embodiments of the present disclosure is shown. However, not all depicted components are necessary, and one or more embodiments may include additional components not shown in the figures. Changes may be made to the arrangement and type of components without departing from the spirit or scope of the claims set forth herein. Additional components, different components, and / or fewer components may be provided. In one embodiment, the calorimeter circuit 300 may be… Figure 2 The radiative calorimeter circuit 200 may include Figure 2 The radiative calorimeter circuit 200 or can be Figure 2 It is part of the calorimeter circuit 200. In one embodiment, the calorimeter circuit 1100 may be part of a camera (e.g., a thermal infrared camera).

[0107] The calorimeter circuit 1100 includes one or more column circuit blocks 1102 (identified as column circuit blocks 1102(1) to 1102(P), where P may represent the desired number of columns in a unit cell array (e.g., 210). Each column circuit block 1102 may be associated with one or more active calorimeters 1104. Figure 11 For clarity, only the one or more effective calorimeters 1104 associated with column circuit block 1102(1) are shown (identified as effective calorimeters 1106(1) to 1106(Q), where Q may represent the number of rows required in the unit cell array), but it should be understood that those not shown in the array may be provided. Figure 11 Other valid calorimeters 1104 are explicitly shown in the diagram and these other valid calorimeters 1104 are associated with other column-associated circuit blocks 1102(2) to 1102(P).

[0108] Each valid calorimeter 1104 may be accompanied by switches 1106 and 1108 for selectively activating and connecting to a corresponding one in the column circuit block 1102. In some embodiments, one or more blind calorimeters (e.g., Figure 6The 625 in the diagram can be additionally associated with each column circuit block 1102. Such a blind calorimeter can be configured to be selectively enabled and connected to each column circuit block 1102 via an accompanying switch, for example, to provide a reference signal level for calibration and other purposes.

[0109] In some aspects, column circuit block 1102 may represent one of column circuits 235, and effective calorimeter 1104 may represent one of effective calorimeters 205 in calorimeter circuit 200, wherein effective calorimeter 205 can be selectively connected to a corresponding one of column circuits 235 via a switch. In this regard, according to various embodiments, calorimeter circuit 1100 may also include column multiplexer 1110, calibration data memory 1112, timing and control circuitry 1114, ramp generator 1116, temperature sensor 1118, processor or other logic device 1120 and / or configuration data memory 1122, all of which may be implemented in a manner similar to the corresponding components of calorimeter circuit 200. According to various embodiments, each column circuit block 1102 may include a thermal short-circuit calorimeter 1124, an amplifier 1126 (operational amplifier), a thermal short-circuit calorimeter 1128 (e.g., a feedback calorimeter), an LPF 1130 (e.g., an RC LPF), and / or a sample-and-hold circuit 1132.

[0110] In various embodiments, the thermal short-circuit calorimeter 1124 may be connected at one end to a power supply voltage node 1134 and at the other end to a circuit path 1136 leading to one or more associated active calorimeters 1104(1)-1104(Q). Generally, the resistance of the thermal short-circuit calorimeter 1124 and the resistance of the active calorimeter 1104 can be determined according to the needs of a particular implementation of the calorimeter circuit 1100, taking into account factors such as the power supply voltage range, the operating characteristics of other components of the calorimeter circuit 1100, the desired bias range, and other implementation parameters. For example, the ratio of the resistance of the thermal short-circuit calorimeter 1124 to the resistance of the active calorimeter 1104 can be set to K, for example, by providing a thermal short-circuit calorimeter 1124 with a resistance of K×Rb, where K can be any desired value for a particular implementation parameter and does not need to be an integer.

[0111] Therefore, on the one hand, bias can be set and maintained across the one connected and enabled of the effective calorimeter 1104 and the thermally short-circuited calorimeter 1124. The inverting input 1138 of amplifier 1126 can be connected to the node (denoted as "Col") between the thermally short-circuited calorimeter 1124 and the effective calorimeter 1104 on circuit path 1136, while the non-inverting input 1140 of amplifier 1126 can be provided with a reference voltage V. REFThus configured, the output 1142 of the offset-adjustable digital-to-analog converter (ODAC) 1144 connected and enabled in the effective calorimeter 1104 and the reference voltage level V appearing at node Col can be adjusted by the offset-adjustable digital-to-analog converter (ODAC) 1144. REF Apply a bias.

[0112] In various embodiments, the ODAC 1144 of each column circuit block 1102 may be coupled to the power supply voltage node 1134 and the common voltage node 1144, and configured to generate a desired voltage level at its output 1142 in response to the offset adjustment bit 1146 (e.g., a string of binary bits indicating the desired offset voltage). That is, the ODAC 1144 of each column circuit block 1102 may apply bias adjustment across the effective calorimeter 1104, which is selectively enabled and electrically connected to each column circuit block 1102.

[0113] In this regard, in some embodiments, the ODAC 1144 can be used to adjust the effective calorimeter bias for the corresponding column circuit block 1102. In some embodiments, the ODAC 1144 can be used to apply per-pixel adjustment to the bias across the effective calorimeter 1104. In such embodiments, the calibration data memory 1112 can be configured to store the corresponding offset adjustment bit 1146 for each pixel in the calorimeter circuit 1100 (e.g., for each of the effective calorimeters 1104), and the timing and control circuitry 1114 can be configured to combine the switching and enabling of each row of the effective calorimeters 1104 to provide the corresponding offset adjustment bit 1146 to the ODAC 1144 of the corresponding one in the column circuit block 1102. In various embodiments, the ODAC 1144 may include a resistor network DAC, a CMOS DAC, or any other suitable type of DAC.

[0114] The radiation calorimeter circuit 1100 may include a non-inverting input 1140 connected to amplifier 1126 to provide a reference voltage V. REF The bias circuit 1148 (e.g., a CMOS bias circuit). In one embodiment, the bias circuit 1148 may include... Figure 6 At least a portion of the bias circuit 600. For example, buffer 640 can provide a reference voltage V to amplifier 1126. REF .

[0115] When a desired level of bias is applied, the resistance change due to incident infrared radiation at the effective calorimeter 1104 produces an amplified output voltage at the output 1150 of amplifier 1126. The output 1150 of amplifier 1126 is connected to LPF 1130, which in an embodiment of calorimeter circuit 1100 can be implemented as a resistor-capacitor (RC) network LPF (e.g., ...). Figure 11 (As shown in the diagram). At the other end, LPF 1130 is connected to sample-and-hold circuit 1132, which can be implemented using one or more switches and one or more capacitors (e.g., ...). Figure 11 As shown in the figure, a filtered analog voltage level (e.g., a filtered analog signal) is maintained to substantially maintain the intensity of the incident infrared radiation received at the effective calorimeter 1104.

[0116] In various embodiments, each column circuit block 1102 may include a comparator 1152, a switch 1154, a capacitor 1156, and a latch 1158, which may be used to convert a filtered analog voltage level captured at the sample-and-hold circuit 1132 into a digital output value (e.g., by performing a ramp-compare A / D conversion). For example, comparator 1152 may be configured to receive a voltage level from the sample-and-hold circuit 1132 and a ramp signal from the ramp generator 1116, and compare the voltage level and the ramp signal to trigger (e.g., generate a signal to close switch 1154) when the ramp signal substantially matches the voltage level.

[0117] In this regard, the calorimeter circuit 1100 may further include a counter 1160 (e.g., a digital counter in some embodiments) configured to increment (or decrement, depending on the implementation of the counter 1160) a count value (e.g., encoded in one or more count signals) in response to a received clock signal. The count value incremented or decremented by the counter 1160 may have a period substantially similar to the ramp signal generated by the ramp generator 1116 (e.g., substantially simultaneously reset to zero or a base value). When the comparator 1152 is triggered, the current count value can be selected and stored as a digital value in a latch 1158. The output of the latch 1158 of each column circuit block 1102 may be coupled to a column multiplexer 1110 configured to multiplex the digital values ​​stored in the latches 1158 for each column circuit block 1102 to generate digital output signals 1162 for all columns in the calorimeter circuit 1100. In various embodiments, timing and control circuitry 1114, processor or other logic device 1120, and / or other components of the calorimeter circuitry 1100 may be configured to generate a digital output signal 1162 for all rows of the active calorimeter 1104 according to a predetermined timing, such that the cascade of the digital output signals 1162 can digitally represent an image frame of infrared radiation received at the active calorimeter 1104 of the calorimeter circuitry 1100. Thus, for example, embodiments of the calorimeter circuitry 300 may be configured to capture a sequence of infrared image frames.

[0118] Notice, Figure 11An example calorimeter circuit is shown, comprising a multi-column and multi-row effective calorimeter forming an FPA to generate analog and / or digital outputs of infrared imaging data. Other examples of calorimeter circuits are provided, for example, in U.S. Patent No. 10,197,448, which is incorporated herein by reference. According to various embodiments, the bias can be based at least on a reference signal V associated with the bias of the effective calorimeter. REF To detect the vacuum health associated with the FPA of various radiation calorimeter circuits.

[0119] Where applicable, the various embodiments provided in this disclosure may be implemented using hardware, software, or a combination of hardware and software. Similarly, where applicable, the various hardware and / or software components described herein may be combined into composite components comprising software, hardware, and / or both, without departing from the spirit of this disclosure. Where applicable, the various hardware and / or software components described herein may be divided into sub-components comprising software, hardware, or both, without departing from the spirit of this disclosure. Furthermore, where applicable, it is contemplated that software components may be implemented as hardware components, and vice versa.

[0120] The software according to this disclosure, such as non-transitory instructions, program code, and / or data, may be stored on one or more non-transitory machine-readable media. It is also contemplated that the software identified herein may be implemented using one or more networked and / or unnetworked general-purpose or special-purpose computers and / or computer systems. Where applicable, the order of the various steps described herein may be changed, combined into compound steps, and / or divided into sub-steps to provide the features described herein.

[0121] The foregoing description is not intended to limit this disclosure to the precise forms disclosed or to a particular field of use. The embodiments described above are illustrative but not limiting of the invention. In view of the disclosure of this invention, various alternative embodiments and / or modifications to the invention, whether expressly described or implied herein, are conceivable. Therefore, the scope of the invention is defined only by the appended claims.

Claims

1. An imaging device, the imaging device comprising: An array of effective detectors, the array of effective detectors being configured to receive an incident scene and generate a detection signal based on the incident scene, the effective detectors being arranged in multiple rows of effective detectors and multiple columns of effective detectors arranged perpendicular to the multiple rows of effective detectors; A plurality of reference detectors are arranged parallel to and adjacent to the plurality of effective detectors, wherein the reference detectors are configured to generate a reference signal for each row of the plurality of effective detectors, and wherein each reference signal corresponds to the temperature of the reference detector; A buffer circuit, configured to store the reference signal; and The processing circuit is connected to the buffer circuit and configured as follows: Multiple expected reference signals are determined, each corresponding to one row of multiple rows of valid detectors, and each expected reference signal is based on the temperature of the reference detector. The vacuum integrity associated with the reference detector is determined at least in part based on one or more of the reference signals and a corresponding expected reference signal. Among them, a bias voltage across the effective detector is generated based on the reference signal.

2. The imaging device according to claim 1, wherein, The processing circuit is configured to determine vacuum integrity by determining the difference between each reference signal and the expected reference signal corresponding to that reference signal.

3. The imaging apparatus of claim 1, further comprising a structure configured to block the incident scene from the reference detector.

4. The imaging device according to claim 1, wherein, The buffer circuit includes a sample-and-hold circuit configured to receive and simultaneously store the values ​​of multiple reference signals, wherein the processing circuit is coupled to the sample-and-hold circuit.

5. The imaging device according to claim 4, wherein, The sample-and-hold circuit is configured to receive the reference signal from the reference detector.

6. The imaging device according to claim 4, wherein, The buffer circuit also includes: A buffer amplifier is connected to the reference detector and the sample-and-hold circuit, wherein the buffer amplifier is configured to receive the reference signal from the reference detector.

7. The imaging device according to claim 6, wherein, The buffer circuit further includes a multiplexer circuit, which is configured as follows: Receive the reference signal from the buffer amplifier; and The reference signal is selectively provided to the sample-and-hold circuit.

8. The imaging device according to claim 4, wherein, The buffer circuit also includes: A multiplexer circuit is connected to the reference detector and the sample-and-hold circuit, wherein the multiplexer circuit is configured to receive the reference signal from the reference detector.

9. The imaging device according to claim 8, wherein, The multiplexer circuit includes multiple multiplexers.

10. The imaging device according to claim 4, wherein, The sample-and-hold circuit includes multiple sample-and-hold components.

11. The imaging device according to claim 10, wherein: The first of the plurality of sample-and-hold components is configured to provide a first reference signal to the processing circuit, while a second reference signal is provided to the second of the plurality of sample-and-hold components.

12. The imaging apparatus of claim 1, further comprising an analog-to-digital converter connected to the buffer circuit and configured to generate digital count values ​​based on the reference signal, wherein, The processing circuitry is coupled to the analog-to-digital converter and configured to determine vacuum integrity based at least on the digital count value and the expected reference signal.

13. The imaging apparatus of claim 1, further comprising a memory device configured to store values ​​of a plurality of expected reference signals, wherein, Each of the plurality of expected reference signals is associated with a corresponding temperature of the reference detector.

14. The imaging apparatus of claim 1, further comprising a temperature sensor configured to measure a plurality of temperatures associated with the reference detector, each temperature corresponding to one of the plurality of rows of effective detectors. in, The first reference detector, the second reference detector, and the third reference detector are configured as follows: A first reference signal, a second reference signal, and a third reference signal are generated for the first row of valid detectors, the second row of valid detectors, and the third row of valid detectors, respectively. as well as A first bias voltage, a second bias voltage, and a third bias voltage are generated for the first row of valid detectors, the second row of valid detectors, and the third row of valid detectors, respectively. The buffer circuit is configured as follows: Receive a first reference signal from the first reference detector; Storing the first reference signal and providing the first reference signal to the processing circuit when a second reference signal is received from the second reference detector; and The second reference signal is stored and provided to the processing circuit when the third reference signal is received from the third reference detector. The processing circuit is configured as follows: A first expected reference signal is determined based on a first temperature corresponding to a first reference signal; A second expected reference signal is determined based on a second temperature corresponding to the second reference signal; and The vacuum integrity associated with the reference detector is determined by determining the difference between at least one of the first reference signal and the second reference signal and a first and / or second expected reference signal corresponding to at least one of the first reference signal and the second reference signal.

15. The imaging device according to claim 1, wherein, Each of the reference detectors includes a calorimeter, and the temperature is the temperature of the readout circuit.

16. The imaging device according to claim 1, wherein, A first reference signal is generated by the reference detector, the first reference signal corresponding to a first temperature of the reference detector and corresponding to a first row of the array, and a first expected reference signal is determined by the processing circuit based on the first temperature of the reference detector, wherein the first reference signal, the first expected reference signal, and the first temperature are associated with a first line time, wherein the first reference signal is sampled around the end of the first line time, and wherein during a second line time: The reference detector is configured to generate a second reference signal, the second reference signal corresponding to a second temperature of the reference detector and corresponding to a second row of the array; The buffer circuit is configured to store the value of the second reference signal; and The processing circuit is configured as follows: A second expected reference signal is determined based on a second temperature associated with the reference detector; and The vacuum integrity associated with the reference detector is determined based at least on the second reference signal and the second expected reference signal.

17. An imaging method, the imaging method comprising: The incident scene is received by an array of effective detectors, wherein the effective detectors are arranged in multiple rows of effective detectors and in multiple columns of effective detectors perpendicular to the multiple rows of effective detectors. A reference signal is generated for each row of a multi-row effective detector by means of multiple reference detectors arranged parallel to and adjacent to the multi-column effective detectors, wherein each reference signal corresponds to the temperature of the reference detector; The reference signal is stored through a buffer circuit; Multiple expected reference signals are determined by the processing circuit, each expected reference signal corresponding to one row of multiple rows of valid detectors, and each expected reference signal is based on the temperature of the reference detector; The processing circuit determines the vacuum integrity associated with the reference detector based on one or more of the reference signals and the expected reference signal corresponding to one or more of the reference signals; and A bias voltage across the effective detector is generated based on the reference signal.

18. The imaging method according to claim 17, wherein, Determining vacuum integrity includes determining the difference between one or more of the reference signals and the expected reference signal corresponding to one or more of the reference signals.

19. The imaging method according to claim 17, wherein, Each of the reference detectors has a structure disposed thereon to block the incident scene from it.

20. The imaging method according to claim 19, further comprising: The effective detector generates a detection signal based on the incident scene.

21. The imaging method according to claim 17, wherein, The storage includes receiving the reference signal via a sample-and-hold circuit of the buffer circuit, wherein the sample-and-hold circuit is connected to the processing circuit.

22. The imaging method according to claim 21, wherein, The reference signal is received from the reference detector by the sample-and-hold circuit.

23. The imaging method according to claim 21, wherein, The storage also includes: The buffer amplifier of the buffer circuit receives the reference signal from the reference detector, wherein the buffer amplifier is connected to the sample-and-hold circuit.

24. The imaging method according to claim 23, wherein, The storage also includes: The reference signal from the buffer amplifier is received through the multiplexer circuit of the buffer circuit; and The reference signal is selectively provided to the sample-and-hold circuit via the multiplexer circuit.

25. The imaging method according to claim 21, wherein, The storage also includes receiving the reference signal from the reference detector via a multiplexer circuit of the buffer circuit, wherein the multiplexer circuit is coupled to the reference detector and the sample-and-hold circuit.

26. The imaging method according to claim 21, further comprising: A first reference signal and a second reference signal are generated by the reference detector, the first reference signal and the second reference signal corresponding to a first temperature and a second temperature of the reference detector, and respectively corresponding to a first row and a second row of the array; and The first reference signal is provided to the processing circuit through the first sample-and-hold component of the sample-and-hold circuit, while the second reference signal is provided to the second sample-and-hold component of the sample-and-hold circuit.

27. The imaging method of claim 17, further comprising generating a digital count value based on the reference signal using an analog-to-digital converter, wherein, The determination of vacuum integrity is based at least on the digital count value and the expected reference signal.

28. The imaging method according to claim 17, further comprising: A first reference signal is generated by a reference detector, the first reference signal corresponding to a first temperature of the reference detector and corresponding to a first row of the array; and The processing circuit determines a first expected reference signal based on a first temperature of the reference detector, wherein the first reference signal, the first expected reference signal, and the first temperature are associated with a first line time, and wherein the first reference signal is sampled approximately at the end of the first line time. The method also includes a second time interval: A second reference signal is generated by the reference detector, the second reference signal corresponding to a second temperature of the reference detector and corresponding to a second row of the array; The value of the second reference signal is stored through the buffer circuit; The processing circuit determines a second expected reference signal based on a second temperature of the reference detector; and The processing circuitry determines the vacuum integrity associated with the reference detector based at least on the value of the second reference signal and the second expected reference signal.

29. The imaging method according to claim 17, further comprising: Measure the temperature corresponding to the reference signal; A first reference signal, a second reference signal, and a third reference signal are generated using a first reference detector, a second reference detector, and a third reference detector, respectively, for the first row of valid detectors, the second row of valid detectors, and the third row of valid detectors. A first bias voltage, a second bias voltage, and a third bias voltage are generated for the first row of valid detectors, the second row of valid detectors, and the third row of valid detectors, respectively, using a first reference detector, a second reference detector, and a third reference detector. The buffer circuit is used to receive the first reference signal from the first reference detector; The buffer circuit provides the first reference signal to the processing circuit when the second reference signal is received from the second reference detector. The buffer circuit provides the second reference signal to the processing circuit when the third reference signal is received from the third reference detector. The processing circuit determines a first expected reference signal based on a first temperature corresponding to a first reference signal. The processing circuit uses the second expected reference signal to determine a second expected reference signal based on a second temperature corresponding to the second reference signal. as well as The vacuum integrity associated with the reference detector is determined by determining the difference between at least one of the first reference signal and the second reference signal and a first and / or second expected reference signal corresponding to at least one of the first reference signal and the second reference signal.

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