A method and circuit for reducing power consumption of an imaging device

Abstract

The embodiment of the present disclosure provides a method and circuit for reducing power consumption of an imaging device, wherein the imaging device at least comprises a pixel array composed of a plurality of SPAD pixels; the method comprises: acquiring light intensity information or / and counting information, wherein the light intensity information comprises a light intensity parameter or a first type of photon counting value of the SPAD pixels in the pixel array, and the counting information comprises a second type of photon counting value of the SPAD pixels in the pixel array; wherein the first type of photon counting value is related to ambient light intensity, and the second type of photon counting value is related to an imaging target; determining an imaging condition according to the light intensity information or the counting information, and adjusting a photon counting rate of the SPAD pixels in the pixel array according to a determination result.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of photon counting imaging technology, and in particular to a method and circuit for reducing power consumption of an imaging device. BACKGROUND

[0002] With the development of Single Photon Avalanche Diode (SPAD) device manufacturing technology and integrated circuits, Single Photon Counting Imaging (PCI) technology based on SPAD has been applied. In a SPAD-based PCI image sensor, each pixel unit has an independent SPAD, quenching circuit and counting circuit. The pixel units are replicated and expanded into an array of M rows and N columns (M and N are both integers greater than 0) of light-sensitive regions. At the same time, components such as readout circuit and control circuit are connected outside the array of light-sensitive regions, which together constitute a PCI image sensor that can capture target optical images.

[0003] Image resolution is one of the important performance indicators of an image sensor. To improve the image resolution, more pixel units need to be integrated in the light-sensitive region of the sensor to form a larger pixel array. However, the expansion of the pixel array not only causes the area of the sensor chip to increase, but also increases the power consumption of the chip. Especially in the case of strong ambient light, the number of SPAD avalanche events per unit time increases, the pixel operating frequency increases, and the current consumption increases. Further, excessive power consumption of the chip not only causes the chip to generate a lot of heat, but also can cause the circuit to fail. SUMMARY

[0004] The present disclosure provides a method and circuit for reducing power consumption of an imaging device.

[0005] In a first aspect, the present disclosure provides a method for reducing power consumption of an imaging device, the imaging device comprising at least a pixel array composed of a plurality of SPAD pixels; the method comprising:

[0006] obtaining light intensity information or / and counting information, the light intensity information comprising a light intensity parameter or a first type of photon counting value of the SPAD pixels in the pixel array, and the counting information comprising a second type of photon counting value of the SPAD pixels in the pixel array; wherein the first type of photon counting value is related to the intensity of ambient light, and the second type of photon counting value is related to an imaging target;

[0007] determining an imaging condition according to the light intensity information or the counting information, and adjusting the photon counting rate of the SPAD pixels in the pixel array according to the determination result.

[0008] In some embodiments, the count information is used for judging the imaging condition and for imaging the imaging target; the light intensity information and the count information are acquired in the same frame or different frames.

[0009] In some embodiments, when the light intensity information and the count information are acquired in different frames, the SPAD pixels used for acquiring the first type of photon count value and acquiring the second type of photon count value are the same, and the light intensity information is acquired in a previous frame and the count information is acquired in a subsequent frame.

[0010] In some embodiments, when the light intensity information and the count information are acquired in the same frame, the SPAD pixels used for acquiring the first type of photon count value and acquiring the second type of photon count value are different, and the light intensity information and the count information are acquired simultaneously.

[0011] In some embodiments, the imaging condition is judged according to the light intensity information, and the photon counting rate of the SPAD pixels in the pixel array is adjusted according to the judgment result, including:

[0012] comparing the light intensity parameter with at least one light intensity threshold value, if the light intensity parameter is greater than or equal to the light intensity threshold value, the photon counting rate of the SPAD pixels in the pixel array is lowered; if the light intensity parameter is less than the light intensity threshold value, the photon counting rate of the SPAD pixels in the pixel array is increased.

[0013] In some embodiments, the imaging condition is judged according to the light intensity information, and the photon counting rate of the SPAD pixels in the pixel array is adjusted according to the judgment result, including:

[0014] comparing the first type of photon count value with at least one judgment threshold value, if the first type of photon count value is greater than or equal to the judgment threshold value, the photon counting rate of the SPAD pixels in the pixel array is lowered; if the first type of photon count value is less than the judgment threshold value, the photon counting rate of the SPAD pixels in the pixel array is increased.

[0015] In some embodiments, the increase of the photon counting rate of the SPAD pixels in the pixel array includes:

[0016] reducing the dead time of the SPAD pixels in the pixel array;

[0017] the lowering of the photon counting rate of the SPAD pixels in the pixel array includes:

[0018] increasing the dead time of the SPAD pixels in the pixel array.

[0019] In some embodiments, judging the imaging condition according to the count information, and adjusting the photon counting rate of the SPAD pixels in the pixel array according to the judging result, comprises:

[0020] comparing the second-type photon counting value with a counting threshold value, and if the second-type photon counting value is equal to the counting threshold value, reducing the photon counting rate of the SPAD pixels in the pixel array to 0.

[0021] In some embodiments, the first-type photon counting value comprises a sum value, an average value or a median of the photon counting values of the SPAD pixels in the pixel array.

[0022] In a second aspect, the embodiments of the present disclosure provide a circuit for reducing power consumption of an imaging device, the imaging device comprising at least a pixel array composed of a plurality of SPAD pixels; the circuit comprising an acquisition circuit, a counting circuit and an adjustment circuit; wherein:

[0023] the acquisition circuit is configured to acquire light intensity information, the light intensity information comprising a light intensity parameter or a first-type photon counting value of the SPAD pixels in the pixel array, the first-type photon counting value being related to ambient light intensity;

[0024] the counting circuit is configured to acquire count information, the count information comprising a second-type photon counting value of the SPAD pixels in the pixel array, the second-type photon counting value being related to an imaging target;

[0025] the adjustment circuit is configured to judge an imaging condition according to the light intensity information or the count information, and adjust the photon counting rate of the SPAD pixels in the pixel array according to the judging result.

[0026] In a third aspect, the embodiments of the present disclosure provide an imaging device, which applies the method of any one of the first aspect, and comprises the circuit of any one of the second aspect.

[0027] Thus, the present disclosure can judge the imaging condition according to the light intensity parameter or the first-type photon counting value, and then adjust the photon counting rate of the SPAD pixels, or judge the imaging condition through the second-type photon counting value, and then adjust the photon counting rate of the SPAD pixels, so as to adjust the photon counting rate of the SPAD pixels under different imaging conditions, reduce the working frequency of the SPAD pixels under high exposure intensity (e.g. strong ambient light), and then reduce the power consumption of the imaging device; and improve the working frequency of the SPAD pixels under low exposure intensity (e.g. dark environment), capture more photons, and improve the imaging effect. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1A gray scale diagram and a corresponding photon counting value of a SPAD pixel provided by an embodiment of the present disclosure;

[0029] Figure 2 A flowchart of a method for reducing power consumption of an imaging device provided by an embodiment of the present disclosure;

[0030] Figure 3 A schematic diagram of a relationship between light intensity (light power) and photon counting rate provided by an embodiment of the present disclosure;

[0031] Figure 4 A schematic diagram of a composition structure of a circuit for reducing power consumption of an imaging device provided by an embodiment of the present disclosure;

[0032] Figure 5 A specific composition structure of a circuit for reducing power consumption of an imaging device provided by an embodiment of the present disclosure Figure 1 ;

[0033] Figure 6 A schematic diagram of a composition structure of a data readout circuit of a pixel array provided by an embodiment of the present disclosure;

[0034] Figure 7 A specific composition structure of a circuit for reducing power consumption of an imaging device provided by an embodiment of the present disclosure Figure 2 ;

[0035] Figure 8 A specific composition structure of a circuit for reducing power consumption of an imaging device provided by an embodiment of the present disclosure Figure 3 ;

[0036] Figure 9 A specific composition structure of a circuit for reducing power consumption of an imaging device provided by an embodiment of the present disclosure Figure 4 ;

[0037] Figure 10 A schematic diagram of a composition structure of an imaging device provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings in the embodiments of the present disclosure. It can be understood that the specific embodiments described herein are only for the purpose of explaining the related application, and are not intended to limit the present disclosure. In addition, it should be noted that, for the purpose of description, only the parts related to the application are shown in the drawings.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used in the description herein is for describing the embodiments of the present disclosure only and is not intended to be limiting of the present disclosure.

[0040] In the following description, reference is made to "some embodiments", which describe a subset of all possible embodiments, but it is understood that "some embodiments" can be the same subset or different subsets as each other and can be combined with each other, without conflict.

[0041] It should be noted that the terms "first", "second", "third" involved in the embodiments of the present disclosure are only to distinguish similar objects, and do not represent a specific order of the objects. Understandably, "first", "second", "third" can be interchanged in a specific order or sequence as allowed, so that the embodiments of the present disclosure described herein can be implemented in an order other than that illustrated or described herein.

[0042] In a SPAD-based PCI image sensor, a pixel can contain one or more pixel units, and each pixel unit contains an independent SPAD. Therefore, the pixel of the PCI image sensor is also called a SPAD pixel. When one or more photons are incident on the SPAD, an avalanche event can be triggered at the SPAD pixel in the working state; the avalanche event causes the quenching circuit to work and output a pulse signal; the number of pulse signals is counted by the downstream counting circuit. The photon counting value of a single SPAD pixel reflects the light intensity of a single point target, and the photon counting value counted by a two-dimensional pixel array can depict a digital image of a target field of view region.

[0043] Referring to Figure 1 , a gray scale chart and its corresponding SPAD pixel photon counting value provided by the embodiments of the present disclosure are shown. As Figure 1 indicated, the gray scale chart is composed of the gray scale corresponding to each SPAD pixel, and the gray scale of each SPAD pixel is represented by the number of photons received by the SPAD pixel or the proportion of the number of photons. Exemplarily, in Figure 1 , the number of photons received by the SPAD pixel (i.e. the photon counting value) is represented. The more photons received by the SPAD pixel, the higher the photon counting value, and the higher the brightness of the image output by the PCI image sensor.

[0044] It should be noted that image resolution is one of the important performance indicators of an image sensor, which reflects the ability of the image sensor to capture details of an optical target. Increasing the image resolution requires integrating more pixel units in the light-sensitive area of the image sensor, expanding the pixel array, and forming a larger pixel array. In the case of uniform field of view area, a larger pixel array can capture more target details.

[0045] However, the expansion of the pixel array not only causes the area of the sensor chip to become larger, but also causes the current consumed by the chip to increase proportionally, and the power consumption of the chip to increase. Especially in the case of strong ambient light, the number of SPAD avalanche events per unit time increases, the working frequency of the pixel increases, and the current consumption increases. Further, the high working power consumption of the chip not only causes the chip to generate a lot of heat and the temperature of the chip to deviate from the appropriate range, but also more seriously, causes the chip to have a high IR drop, and has the risk of circuit function failure. In the related art, the method for reducing the power consumption of the chip is mainly through low-power circuit design and manufacturing, but the difficulty is high and the cost is increased.

[0046] Based on this, the embodiment of the present disclosure provides a method for reducing the power consumption of an imaging device, the imaging device at least including a pixel array composed of a plurality of SPAD pixels; the method comprising: obtaining light intensity information or / and counting information, the light intensity information including a light intensity parameter or a first type of photon counting value of the SPAD pixels in the pixel array, and the counting information including a second type of photon counting value of the SPAD pixels in the pixel array; wherein the first type of photon counting value is related to the ambient light intensity, and the second type of photon counting value is related to the imaging target; judging the imaging condition according to the light intensity information or the counting information, and adjusting the photon counting rate of the SPAD pixels in the pixel array according to the judgment result. In this way, the present disclosure can judge the imaging condition according to the light intensity parameter or the first type of photon counting value, and then adjust the photon counting rate of the SPAD pixels, or judge the imaging condition through the second type of photon counting value, and then adjust the photon counting rate of the SPAD pixels, so as to adjust the photon counting rate of the SPAD pixels under different imaging conditions, reduce the working frequency of the SPAD pixels under high exposure intensity (such as strong ambient light), and then reduce the power consumption of the imaging device; under low exposure intensity (such as a dark environment), the working frequency of the SPAD pixels is increased to capture more photons and improve the imaging effect.

[0047] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0048] In an embodiment of the present disclosure, referring to Figure 2 which shows a flowchart of a method for reducing the power consumption of an imaging device provided by an embodiment of the present disclosure. As shown in Figure 2 , the method can include:

[0049] S101, obtaining light intensity information or / and counting information, the light intensity information including a light intensity parameter or a first type of photon counting value of the SPAD pixels in the pixel array, and the counting information including a second type of photon counting value of the SPAD pixels in the pixel array.

[0050] wherein the first type of photon counting value is related to the ambient light intensity, and the second type of photon counting value is related to the imaging target; the imaging device at least including a pixel array composed of a plurality of SPAD pixels.

[0051] Here, the imaging device can also be referred to as an imaging apparatus, and the method provided in the embodiments of the present disclosure can be a method for reducing power consumption of a SPAD-based imaging apparatus.

[0052] It should be noted that an additional photoelectric sensor can be provided to measure the ambient light intensity alone to obtain a light intensity parameter to determine the light intensity information, or a first type of photon count value related to the ambient light intensity can be obtained to determine the light intensity information, and no specific limitation is made in this regard. Further, the present embodiment can not simultaneously obtain the light intensity parameter and the first type of photon count value, when the light intensity parameter is used to represent the light intensity information, the first type of photon count value is not used to represent the light intensity information, and vice versa.

[0053] It should be further noted that in different application scenarios, the SPAD pixel can only include a SPAD device, or can include a SPAD device, a corresponding quenching circuit, and a counting circuit, and no specific limitation is made in this regard. The SPAD device is used to sense photons and generate a pulse signal; the quenching circuit is used to quench the SPAD; and the counting circuit is used to count the pulse signal to obtain a photon count value.

[0054] It should be further noted that the first type of photon count value is related to the environment, and can be used to determine the ambient light intensity, and the greater the value of the first type of photon count value, the stronger the ambient light intensity; the second type of photon count value is related to the information of the imaging target itself, and through the second type of photon count value, the imaging target can be imaged. In the embodiments of the present disclosure, the process of capturing photons by the SPAD pixel to obtain the first type of photon count value or the second type of photon count value is as follows:

[0055] (1) The SPAD in the waiting state is excited by light to generate photoelectrons, and after causing an avalanche event, the quenching circuit works to quench the avalanche, and then the quenching circuit recharges the SPAD to restore it to the waiting state.

[0056] (2) In the above avalanche process, the quenching circuit will also generate a digital pulse signal to the downstream counting circuit, and the counting circuit (whether asynchronous counting or synchronous counting) belongs to a digital circuit structure, and after detecting the pulse signal generated by the quenching circuit, the photon count value is incremented by one.

[0057] (3) After the SPAD is restored, it waits for light excitation again, and the SPAD pixel unit performs processes (1) and (2) again. Within the exposure time, the above processes are repeated.

[0058] It should be noted that each SPAD pixel has a corresponding independent counting circuit, and different SPAD pixels are generally not counted by the same counting circuit. If the circuit is simplified to improve the integration of the chip, different SPAD pixels can share the counting circuit, but different SPAD pixels need to be counted in time (or staggered) to avoid motion artifacts.

[0059] In some embodiments, the first type of photon counting value includes a sum value, an average value, or a median of the photon counting values of the SPAD pixels in the pixel array. Specifically, in practical applications, one of the sum value, the average value, and the median of the photon counting values can be selected as the first type of photon counting value according to actual conditions. It should be noted that the standards for judging the light intensity information (return light intensity) are different when the above three types of values are used as the first type of photon counting value. For example, the first type of photon counting value can be the average value (C avr ) of the photon counting values of all or part of the SPAD pixels in the pixel array.

[0060] S102, judging the imaging condition according to the light intensity information or the counting information, and adjusting the photon counting rate of the SPAD pixels in the pixel array according to the judgment result.

[0061] It should be noted that if the light intensity of the optical target corresponding to a certain SPAD pixel is stronger, the number of photons incident on this SPAD pixel in the exposure time is greater, and therefore more processes (1) and (2) are triggered, and the photon counting value in the counting circuit is also higher. Obviously, the higher the photon counting value of the SPAD pixel, the higher the pixel counting rate corresponding to the SPAD pixel. The pixel counting rate can be understood as the counting frequency, which represents the photon counting value per unit time, as shown in formula (1):

[0062] CR = C / T E (1);

[0063] Wherein, CR represents the pixel counting rate, C represents the photon counting value, T E represents the exposure time.

[0064] It can be understood that if the unit power consumption of the SPAD pixel working once (i.e., the photon counting value plus one) is P0, then the total power consumption P total of the SPAD pixel during the exposure process is as shown in formula (2):

[0065] P total = C x P0 (2);

[0066] Wherein, C represents the photon counting value.

[0067] It can be understood from formula (1) and formula (2) that the total power consumption of the SPAD pixel during one exposure process is as shown in formula (3):

[0068] P total = CR x T E x P0 (3);

[0069] According to formula (3), by adjusting the photon counting rate of the SPAD pixel, the total power consumption of the SPAD pixel in the pixel array can be adjusted.

[0070] Here, the photon counting rate of the SPAD pixel can also be understood as the pixel counting rate described above.

[0071] It should be further noted that the imaging condition refers to the intensity of the ambient light or whether the counting circuit is in a saturated state. When it is judged that the intensity of the ambient light is large or the counting circuit is in a saturated state, the photon counting rate of the SPAD pixel in the pixel array is correspondingly reduced. Conversely, when it is judged that the counting circuit is in an unsaturated state and the intensity of the ambient light is small, the photon counting rate of the SPAD pixel in the pixel array is increased. It can be understood that when the counting circuit is in a saturated state, it means that a large number of photons are captured by the SPAD pixel, which also indicates that the ambient light is relatively strong. Among them, the counting circuit saturation refers to the counting circuit being full, and the register included in the counting circuit has stored the maximum value, and the counting value cannot continue to increase.

[0072] In some embodiments, the counting information is used for the judgment of the imaging condition and for imaging the imaging target; the intensity information and the counting information are acquired in the same frame or different frames.

[0073] It should be noted that the counting information is used for the judgment of the imaging condition, which actually judges whether the counting circuit of the SPAD pixel is saturated, that is, whether the counting value in the counting circuit reaches its maximum counting value; and the counting information is used for imaging the imaging target, which refers to the photon counting data (photon counting value) for imaging the imaging target.

[0074] In the embodiments of the present disclosure, whether the intensity information and the counting information are acquired in the same frame depends on the acquisition method of the intensity information. Specifically, when the intensity information is obtained by an additional photoelectric sensor to obtain the intensity parameter, and when the intensity information is obtained by acquiring the first type of photon counting value of part of the SPAD pixels in the pixel array, the intensity information and the counting information can be acquired in the same frame; when the intensity information is obtained by acquiring the first type of photon counting value of all the SPAD pixels in the pixel array, the intensity information and the counting information need to be acquired in different frames. In this way, it can be ensured that the judgment process of the imaging condition and the acquisition process of the imaging data do not interfere with each other, and the functional stability of the imaging device is ensured. Here, a frame refers to a complete imaging process, including exposure, data transfer, data processing and other steps.

[0075] In some embodiments, when the light intensity information and the count information are acquired in different frames, the SPAD pixels used to acquire the first type of photon count value and the second type of photon count value are the same, and the light intensity information is acquired in a previous frame and the count information is acquired in a subsequent frame.

[0076] It should be noted that this is a case of acquiring, judging light intensity information and adjusting the photon counting rate of the SPAD pixel, i.e., acquiring and judging the light intensity information in a previous frame, and adjusting the photon counting rate of the SPAD pixel according to the light intensity information of the previous frame in the current frame. This case requires one imaging, and the SPAD pixels used to acquire the light intensity information and the count information can be multiplexed, i.e., the SPAD pixels used to acquire the light intensity information and the count information can be multiplexed. Here, when the light intensity information and the count information are acquired in different frames, the first type of photon count value acquired can be the average value of the photon count values of all SPAD pixels in the pixel array (C avr ).

[0077] It should also be noted that when the light intensity information and the count information are acquired in different frames, the imaging condition needs to be judged according to the light intensity information first, and then the photon counting rate of the SPAD pixel is adjusted according to the judgment result to image the imaging target, so the light intensity information is acquired in a previous frame, and then the count information is acquired in a subsequent frame. It can be understood that the time of the frame in which the light intensity information is acquired and the time of the frame in which the imaging target is imaged can be different, specifically, the time of the frame in which the light intensity information is acquired can be shorter than the time of the frame in which the imaging target is imaged, to improve the imaging efficiency.

[0078] It should also be noted that generally two frames are used to acquire the light intensity information and the count information, one frame is used to acquire the light intensity information, and one frame is used to acquire the count information and image the imaging target. If more than two frames are used, it can be that multiple frames are used to acquire the light intensity information, so that more accurate light intensity information can be determined, or it can be that multiple frames are used to image the imaging target, so that the imaging details can be better. In the embodiments of the present disclosure, the ratio of the number of frames used to acquire the light intensity information and the number of frames used to image the imaging target is not specifically limited.

[0079] In other embodiments, when the light intensity information and the count information are acquired in the same frame, the SPAD pixels used to acquire the first type of photon count value and the second type of photon count value are different, and the light intensity information and the count information are acquired simultaneously.

[0080] It should be noted that this is another case of obtaining and judging light intensity information and adjusting the photon counting rate of the SPAD pixel, that is, obtaining and judging light intensity information and adjusting the photon counting rate of the SPAD pixel at the same time in the same frame. This case also needs to be imaged once, and the light intensity information is obtained at the same time in the process of imaging the imaging target, but the SPAD pixels for obtaining the light intensity information and the counting information cannot be reused, that is, the SPAD pixels for obtaining the light intensity information and the SPAD pixels for imaging the imaging target cannot be reused. Here, when the light intensity information and the counting information are obtained in the same frame, the first type of photon counting value obtained can be the average value of the photon counting values of part of the SPAD pixels in the pixel array (C avr ).

[0081] In the embodiments of the present disclosure, when the light intensity information and the counting information are obtained in the same frame, the total time of the imaging condition judgment and the imaging process can be shortened. It can be understood that the light intensity information can be obtained by an additional photoelectric sensor to obtain the light intensity parameter, or by obtaining the first type of photon counting value of part of the SPAD pixels in the pixel array. It should be noted that when the light intensity parameter is obtained by the foregoing second way (that is, obtaining the first type of photon counting value of part of the SPAD pixels), the light intensity information and the counting information can be obtained simultaneously and synchronously, that is, the light intensity information is obtained to judge the imaging condition, and the photon counting rate of the SPAD pixels of the pixel array is adjusted at the same time, real-time judgment and real-time adjustment, and the imaging is more efficient.

[0082] In some embodiments, the light intensity information and the counting information can be obtained in the same frame, but the light intensity information can be obtained earlier than the imaging of the imaging target, that is, after obtaining the light intensity information and judging the imaging condition, the photon counting rate of the SPAD pixel is adjusted according to the judgment result, and then the imaging target is imaged, which can reduce the probability of repeatedly adjusting the photon counting rate of the SPAD pixel due to unstable factors in the process of obtaining the light intensity information, and improve the imaging efficiency.

[0083] In some embodiments, when the light intensity information includes the light intensity parameter, the light intensity parameter is compared with the first threshold value. In the case that the first threshold value has only one threshold value, if the light intensity parameter is greater than or equal to the first threshold value, the photon counting rate of the SPAD pixel in the pixel array is lowered.

[0084] It should be noted that the photon counting rate of all or part of the SPAD pixels in the pixel array can be lowered. Specifically, the photon counting rate of all the SPAD pixels in the pixel array can be lowered if the difference between the light intensity parameter and the first threshold is large, indicating that the photon counting rate of the SPAD pixels is too high; otherwise, only the photon counting rate of part of the SPAD pixels in the pixel array can be lowered. The photon counting rate of all or part of the SPAD pixels can be selected according to actual conditions, and no specific limitation is made thereto.

[0085] The first threshold can include multiple thresholds, that is, the first threshold can include at least one light intensity threshold. In some embodiments, the imaging condition is determined according to the light intensity information, and the photon counting rate of the SPAD pixels in the pixel array is adjusted according to the determination result, including:

[0086] The light intensity parameter is compared with the at least one light intensity threshold. If the light intensity parameter is greater than or equal to the light intensity threshold, the photon counting rate of the SPAD pixels in the pixel array is lowered; if the light intensity parameter is less than the light intensity threshold, the photon counting rate of the SPAD pixels in the pixel array is increased.

[0087] In the embodiments of the present disclosure, different light intensity threshold ranges can correspond to different optimal photon counting rates. Specifically, the optimal photon counting rate corresponding to the light intensity parameter range can be obtained through a large number of imaging tests, and then a mapping relationship table of "light intensity parameter-photons counting rate" is formed. In the actual imaging process, after the light intensity parameter is obtained, the light intensity parameter range to which the light intensity parameter belongs can be found in the mapping relationship table, and then the optimal photon counting rate corresponding to the light intensity parameter range is found, so that the photon counting rate of the SPAD pixels in the pixel array is adjusted to the optimal value.

[0088] After the light intensity parameter is obtained, the light intensity parameter range to which the light intensity parameter belongs can be found in the mapping relationship table, which can be understood as follows: the at least one light intensity threshold is sequentially decreased in value, and the light intensity parameter is sequentially compared with these light intensity thresholds. If the light intensity parameter is greater than or equal to the maximum light intensity threshold, the photon counting rate of the SPAD pixels is lowered to the photon counting rate corresponding to the light intensity parameter range in which the maximum light intensity threshold is located. If the light intensity parameter is less than the maximum light intensity threshold, the next smaller light intensity threshold is compared, until the light intensity parameter is greater than or equal to a light intensity threshold and less than the previous light intensity threshold, and then the light intensity parameter range to which the light intensity parameter belongs is determined as between the light intensity threshold and the previous light intensity threshold, and then the photon counting rate of the SPAD pixels is lowered to the photon counting rate corresponding to the light intensity parameter range.

[0089] Exemplarily, if the light intensity parameter is greater than or equal to the light intensity threshold 1 and less than the light intensity threshold 2, the photon counting rate of the SPAD pixel is adjusted to the photon counting rate corresponding to the light intensity parameter range of the light intensity threshold 1 to the light intensity threshold 2.

[0090] In addition, if the light intensity parameter is less than the minimum light intensity threshold, the photon counting rate of the SPAD pixel is increased to the photon counting rate corresponding to the light intensity parameter range of the minimum light intensity threshold. In this way, the adjustment can be started when the average light intensity is weak, and the power consumption increase is within an acceptable range, and the dynamic range can also be increased.

[0091] It should be noted that the photon counting rate of all or part of the SPAD pixels can be selected according to actual conditions, and no specific limitation is made.

[0092] In some embodiments, when the light intensity information includes the first type of photon counting value, the first type of photon counting value is compared with a second threshold (C th_hi ). In the case where the second threshold has only one threshold, if the first type of photon counting value is greater than or equal to the second threshold, the photon counting rate of the SPAD pixel in the pixel array is reduced.

[0093] It should be noted that the photon counting rate of all or part of the SPAD pixels in the pixel array can be reduced. Specifically, the difference between the first type of photon counting value and the second threshold can be determined, and exemplarily, if the difference is large, it indicates that the photon counting rate of the SPAD pixel is too high, and the photon counting rate of all the SPAD pixels in the pixel array can be reduced. Conversely, only the photon counting rate of part of the SPAD pixels in the pixel array can be reduced. The photon counting rate of all or part of the SPAD pixels can be selected according to actual conditions, and no specific limitation is made.

[0094] The second threshold can include multiple thresholds, that is, the second threshold can include at least one judgment threshold (C th0 , C th1 , C th2 …), in some embodiments, the imaging condition is judged according to the light intensity information, and the photon counting rate of the SPAD pixel in the pixel array is adjusted according to the judgment result, including:

[0095] The first type of photon counting value is compared with at least one judgment threshold, if the first type of photon counting value is greater than or equal to the judgment threshold, the photon counting rate of the SPAD pixel in the pixel array is reduced; if the first type of photon counting value is less than the judgment threshold, the photon counting rate of the SPAD pixel in the pixel array is increased.

[0096] In the embodiments of the present disclosure, different judgment threshold ranges can correspond to different optimal photon counting rates. Specifically, the optimal photon counting rate corresponding to the first-type photon counting value range can be obtained through a large number of imaging tests, and then a mapping relationship table of the first-type photon counting value-optimal photon counting rate can be formed. In the actual imaging process, after the first-type photon counting value is obtained, the first-type photon counting value range to which the first-type photon counting value belongs can be found in the mapping relationship table, and then the optimal photon counting rate corresponding to the first-type photon counting value range can be found, so that the photon counting rate of the SPAD pixel in the pixel array is adjusted to the optimal value.

[0097] In the embodiments of the present disclosure, after the first-type photon counting value is obtained, the first-type photon counting value range to which the first-type photon counting value belongs can be found in the mapping relationship table, which can be understood as follows: the at least one judgment threshold is sequentially reduced in value, and the first-type photon counting value is sequentially compared with the judgment thresholds. If the first-type photon counting value is greater than or equal to the maximum judgment threshold, the photon counting rate of the SPAD pixel is adjusted to the photon counting rate corresponding to the first-type photon counting value range in which the maximum judgment threshold is located. If the first-type photon counting value is less than the maximum judgment threshold, the first-type photon counting value is compared with the next smaller judgment threshold, until the first-type photon counting value is greater than or equal to a judgment threshold and less than a previous judgment threshold, the first-type photon counting value range to which the first-type photon counting value belongs is determined to be between the judgment threshold and the previous judgment threshold, and then the photon counting rate of the SPAD pixel is adjusted to the photon counting rate corresponding to the first-type photon counting value range.

[0098] For example, if the first-type photon counting value is greater than or equal to the judgment threshold 1 and less than the judgment threshold 2, the photon counting rate of the SPAD pixel is adjusted to the photon counting rate corresponding to the first-type photon counting value range of the judgment threshold 1 to the judgment threshold 2.

[0099] In addition, if the first-type photon counting value is less than the minimum judgment threshold, the photon counting rate of the SPAD pixel is adjusted to the photon counting rate corresponding to the first-type photon counting value range in which the minimum judgment threshold is located. In this way, the adjustment can be started when the average light intensity is weak, the power consumption increase is within an acceptable range, and the dynamic range can also be increased.

[0100] It should be noted that the photon counting rate of all or part of the SPAD pixels can be adjusted according to the actual situation, and the adjustment of the photon counting rate of all or part of the SPAD pixels is not limited.

[0101] Referring to Figure 3 , a schematic diagram of the relationship between the light intensity (light power) and the photon counting rate is shown. As shown in Figure 3 , the abscissa is the light power (P thThe vertical axis represents the photon count rate (CR), and A and B represent different SPAD pixels.

[0102] It should be noted that there is a positive correlation between light intensity and light power; the greater the light power, the stronger the light intensity; conversely, the smaller the light power, the weaker the light intensity.

[0103] As can be derived from formula (1), the photon count value can be obtained through formula (4):

[0104] C = CR × T E (4);

[0105] Where C represents the photon count value, CR represents the photon count rate, and T E Indicates the exposure time.

[0106] As shown in formula (4), reducing the photon count rate CR can suppress the photon count value.

[0107] It should also be noted that the photon count rate (CR) is negatively correlated with the dead time of SPAD pixels; increasing the dead time can decrease the photon count rate. Under the same light intensity conditions (i.e., the same light power), because the dead time of SPAD A is shorter than that of SPAD B (T... C A <T C Therefore, the photon count rate of SPAD A is greater than the photon count rate of SPAD B (CR). max A>CR max B).

[0108] It should be noted that during the SPAD triggering, quenching, and recovery processes, it will not be triggered by other photons. During this time period, photons incident on the SPAD will not cause the processes (1) and (2) described above, and the pulse signal will not be counted. This time period is called the dead time T. C In particular, an increase in the dead time of SPAD pixels leads to a decrease in the photon count rate. The stronger the light intensity, the greater the decrease in the photon count rate.

[0109] like Figure 3 As shown, P th C indicates that at low light power, SPAD A and SPAD B have essentially the same photon count rate, even though their dead times differ. In other words, in low-light environments, the photon count rate is less affected by the dead time, and SPAD A and SPAD B have essentially the same photon count rate. As light intensity increases, the dead time of the SPAD pixel has a greater impact on its photon count rate; the shorter the dead time, the higher the photon count rate. Therefore, the photon count rate of SPAD B is lower than that of SPAD A.

[0110] Specifically, when the optical power is low, due to weak light intensity and small number of photons, the number of photons reaching the SPAD is small, and the time interval between two adjacent photons reaching the SPAD is more likely to be much greater than the dead time of SPAD A and SPAD B. Even if the dead time of the SPAD is increased, the photon counting rate will not change or change little. Therefore, when the optical power is low, even if the dead time of SPAD A and SPAD B is different, the number of photons responded by them per unit time is close, so the photon counting rates of SPAD A and SPAD B are close.

[0111] With the increase of light intensity, the number of photons increases, and the number of photons reaching the SPAD is more. More photons will arrive in a concentrated manner, and the time interval between two adjacent photons reaching the SPAD is very small, which may be less than the dead time of the SPAD. At this time, the dead time of the SPAD will directly affect the number of photons that can be responded by the SPAD per unit time. If the dead time of the SPAD is increased, most of the photons arriving in a concentrated manner will fall within the dead time and cannot be counted, and the photon counting rate will decrease to a great extent. Because the dead time of SPAD A is less than the dead time of SPAD B (T C A<T C B), the photon counting rate of SPAD B is less than the photon counting rate of SPAD A. Therefore, by judging the target light intensity, the dead time of the SPAD pixel can be adjusted in real time, so as to reduce the power consumption.

[0112] In some embodiments, increasing the photon counting rate of the SPAD pixel in the pixel array comprises:

[0113] decreasing the dead time of the SPAD pixel in the pixel array;

[0114] decreasing the photon counting rate of the SPAD pixel in the pixel array comprises:

[0115] increasing the dead time of the SPAD pixel in the pixel array.

[0116] It should be noted that the present embodiment can correspond to the multiple-grade light intensity threshold in the first threshold and the multiple-grade judgment threshold in the second threshold, and has multiple-grade dead time, that is, the mapping relationship table of "light intensity parameter- photon counting rate- dead time" or the mapping relationship table of "first-type photon counting value- photon counting rate- dead time" can be obtained through a large number of tests. Exemplarily, one light intensity parameter range corresponds to one dead time, and when the light intensity parameter falls into a certain light intensity parameter range, the dead time of the SPAD pixel is adjusted to the value corresponding to the light intensity parameter range. Similarly, one first-type photon counting value range corresponds to one dead time, and when the first-type photon counting value falls into a certain first-type photon counting value range, the dead time of the SPAD pixel is adjusted to the value corresponding to the first-type photon counting value range.

[0117] In addition, in the embodiments of the present disclosure, increasing the dead time of the SPAD pixel can not only reduce the total power consumption P total of the SPAD pixel by reducing the photon counting rate, but also reduce the unit power consumption P0.

[0118] In some embodiments, the imaging condition is judged according to the counting information, and the photon counting rate of the SPAD pixel in the pixel array is adjusted according to the judgment result, including:

[0119] The second-type photon counting value is compared with the counting threshold, and if the second-type photon counting value is equal to the counting threshold, the photon counting rate of the SPAD pixel in the pixel array is adjusted to 0.

[0120] It should be noted that the counting threshold (C max ) represents the upper limit of the counting value when the counting circuit is full or the threshold when the counting circuit is in a saturated state, that is, the maximum value that can be stored in the register included in the counting circuit.

[0121] Here, when the second-type photon counting value is equal to the counting threshold, it means that the counting circuit is in a saturated state.

[0122] If the unit power consumption of the SPAD pixel working once (that is, the photon counting value plus one) is P0, then in the exposure process before the counting circuit is in a saturated state, the total power consumption P total of the SPAD pixel can be obtained by formula (2) described above. In the exposure process after the counting circuit is in a saturated state, because the counting circuit is already saturated, new avalanche events and quenching processes in the SPAD pixel will not increase the photon counting value of the counting circuit, but will increase the power consumption. Therefore, after the counting circuit is in a saturated state, the photon counting rate of the SPAD pixel in the pixel array needs to be adjusted to 0.

[0123] It should be further noted that when the ambient light intensity is very strong, the photons of the ambient light can also make the counting circuit in a saturated state in a very short time. Specifically, during the imaging process, the pixel array will receive not only the photons related to the imaging target but also the photons of the ambient light, and the full counting value of the counting circuit will have not only the counting value of the photons of the imaging target but also the counting value of the photons of the ambient light.

[0124] In some embodiments, the method for reducing the photon counting rate of the SPAD pixel in the pixel array to 0 comprises: turning off the counting circuit of the SPAD pixel.

[0125] In some embodiments, the counting circuit can comprise a quenching circuit, and the turning off of the counting circuit can specifically be the turning off of the quenching circuit.

[0126] It should be further noted that in addition to turning off the quenching circuit of the SPAD pixel, the exposure enable signal of the SPAD pixel can also be turned off, and the reverse bias voltage of the two poles of the SPAD pixel can also be reduced or the reverse bias voltage can be directly removed. The specific mode is not specifically limited in the embodiments of the present disclosure, as long as the SPAD pixel can be turned off.

[0127] The embodiments of the present disclosure provide a method for reducing the power consumption of an imaging device, which can overcome the defect of the high power consumption of the SPAD-based PCI image sensor under strong ambient light by judging the target light intensity in real time, feeding back the adjustment of the dead time of the SPAD pixel, or turning off the quenching circuit after the counting circuit of the SPAD pixel is in a saturated state, so as to reduce the power consumption of the image sensor.

[0128] In another embodiment of the present disclosure, referring to Figure 4 which shows the composition structure schematic diagram of the circuit for reducing the power consumption of the imaging device provided by the embodiments of the present disclosure. As Figure 4 shown, the imaging device 20 at least comprises a pixel array 21 composed of a plurality of SPAD pixels; the circuit for reducing the power consumption of the imaging device 30 can comprise an acquisition circuit 31, a counting circuit 32 and an adjustment circuit 33; wherein:

[0129] The acquisition circuit 31 is configured to acquire light intensity information, the light intensity information comprising a light intensity parameter or a first type of photon counting value of the SPAD pixel in the pixel array 21, the first type of photon counting value being related to the ambient light intensity;

[0130] The counting circuit 32 is configured to acquire counting information, the counting information comprising a second type of photon counting value of the SPAD pixel in the pixel array 21, the second type of photon counting value being related to the imaging target;

[0131] The adjustment circuit 33 is configured to judge the imaging condition according to the light intensity information or the counting information, and to adjust the photon counting rate of the SPAD pixel in the pixel array 21 according to the judgment result.

[0132] It should be noted that the circuit 30 for reducing power consumption of the imaging device provided in the embodiments of the present disclosure applies the method for reducing power consumption of the imaging device as described above.

[0133] It should also be noted that the embodiments can not acquire the light intensity parameter and the first type of photon count value at the same time. If the acquisition circuit 31 acquires the first type of photon count value to represent the light intensity information, i.e., acquires the light intensity information through the SPAD pixels in the pixel array 21, the counting circuit 32 of the pixel array 21 can also be multiplexed as the acquisition circuit 31. If the acquisition circuit 31 acquires the light intensity parameter to represent the light intensity information, an additional photoelectric sensor and corresponding circuit are used to achieve it. Exemplarily, the specific implementation of the embodiments of the present disclosure is described in detail taking the acquisition circuit 31 acquiring the first type of photon count value to represent the light intensity information as an example.

[0134] Referring to Figure 5 , a specific component structure of a circuit for reducing power consumption of an imaging device provided in the embodiments of the present disclosure is shown Figure 1 .

[0135] In the embodiments of the present disclosure, taking the case of using the first type of photon count value as the light intensity information, judging the imaging condition according to the light intensity information, and adjusting the photon counting rate of the SPAD pixels according to the light intensity information of the previous frame in the current frame as an example, as shown in Figure 5 , the circuit 30 includes a readout module 41, a signal processing module 42, and a quenching control module 43. The pixel array 21 is connected with the readout module 41, the readout module 41 is connected with the signal processing module 42, and the quenching control module 43 is connected with the signal processing module 42 and the pixel array 21.

[0136] Here, the first type of photon count value representing the light intensity information acquired in the previous frame is transmitted to the signal processing module 42 via the readout module 41.

[0137] It should be noted that exemplarily, the signal processing module 42 counts and analyzes the average value (C avr ) of the photon count values of all the SPAD pixels in the pixel array 21. avr If C th_hi is greater than a set second threshold value (C Cth_hi ), the signal processing module 42 sends an adjustment signal to the quenching control module 43 in the current frame, and the quenching control module 43 adjusts the dead time of all or part of the SPAD pixels in the pixel array 21 to T th_hi . Further, the second threshold value (C th0 ) can include multiple programmable judgment threshold values C th1 , C th2 …, i.e., multiple programmable judgment threshold values C th0 , Cth1 , C th2 … and the corresponding multi-notch dead time T Cth0 , T Cth1 , T Cth2 …, so that the dead time of the SPAD pixel can be adjusted to the corresponding value according to the comparison of the judgment threshold. The specific judgment and setting method can be referred to the foregoing content, and the embodiments of the present disclosure will not be described again.

[0138] It should be further pointed out that the quenching control module 43 adjusts the dead time of the SPAD pixel by generating a control signal and outputting it to the pixel array 21. The control signal is a signal that adjusts the size of the dead time of the SPAD pixel.

[0139] It should be further pointed out that all SPAD pixels share one readout module 41 and signal processing module 42. Referring to Figure 6 , a schematic diagram of the composition structure of a data readout circuit of a pixel array provided by an embodiment of the present disclosure is shown. As Figure 6 indicated, the photon count value on the SPAD pixel in the pixel array 21 is transferred row by row to the shift register module (corresponding to the readout module 41 in Figure 5 ), and then transferred from the shift register module to the signal processing module 42.

[0140] Referring to Figure 7 , a specific composition structure schematic diagram of a circuit for reducing the power consumption of an imaging device provided by an embodiment of the present disclosure is shown. Figure 2 .

[0141] In the embodiments of the present disclosure, taking the case of using the first type of photon count value as the light intensity information, judging the imaging condition according to the light intensity information, and simultaneously acquiring the light intensity information and adjusting the dead time of the SPAD pixel in the same frame as an example, as Figure 7 indicated, the SPAD pixels 211 (only one label is shown in the figure) in the selected part of the region in the pixel array 21 are used to obtain the first type of photon count value as the light intensity information; during the exposure process, the selected SPAD pixels 211 are transmitted to the external signal processing module 42 through the readout channel 44; the signal processing module 42 counts and analyzes the data of the selected SPAD pixels 211, extracts the characteristic parameters, for example, the average value (C avr ) of the first type of photon count value of the SPAD pixel 211.

[0142] It should be noted that the size of the partial region is not limited, as long as there are SPAD pixels 211 for measuring light intensity. In addition, the SPAD pixels 211 in the partial region can be distributed in the pixel array 21 to avoid the problem of single-point light intensity inaccuracy. Preferably, the edge SPAD pixels in the pixel array 21 are used for light intensity measurement, so that the photon sampling error of light intensity measurement is smaller; and the center SPAD pixels in the pixel array 21 are used for photon counting imaging.

[0143] It should also be noted that the dead time of all SPAD pixels in the pixel array 21 can be increased, or the dead time of all SPAD pixels in the pixel array 21 for imaging (i.e. in addition to the SPAD pixels 211) can be increased, and no specific limitation is made.

[0144] It should also be noted that, Figure 7 The readout channel 44 in Figure 5 The readout module 41 in

[0145] Referring to Figure 8 , a specific component structure of a circuit for reducing power consumption of an imaging device is shown Figure 3 .

[0146] In the embodiment of the present disclosure, as shown in Figure 8 , the counting circuit 32 can include a counter 321 and a quenching module 322 in addition to the SPAD pixel, wherein the counter 321 can include a plurality of cascaded registers 3211 (only one label is shown in the figure), and the plurality of registers 3211 are cascaded as a conventional circuit structure in the related art, and the circuit structure of the quenching module 322 can adopt a common quenching structure in the related art, and the present disclosure will not be repeated here.

[0147] It should be noted that the control module 53 is used to generate an exposure enable signal, and during the effective period of the exposure enable signal, the pixel array 21 is in an exposure state and can sense photons to generate a photon counting value; when the exposure enable signal is invalid, the SPAD pixel exposure ends and cannot sense photons. Among them, when the exposure enable signal is invalid, the pixel array 21 is in a data transfer mode, and the photon counting value is transferred and read out row by row.

[0148] Here, the counter 321 is composed of a plurality of registers 3211 for buffering the photon counting value of the SPAD pixel. Among them, the first register 3211 (register D LSB ) is used to store the least significant bit (LSB) value, and the last register 3211 (register D MSB) for storing the value of the Most Significant Bit (MSB). When the plurality of registers 3211 are full, the Q end of the register D MSB outputs a "1", indicating that the counter 321 has been full, and the subsequent photons incident on the SPAD pixel cannot be counted, the photon count value remains unchanged but there is power consumption, that is, the counting circuit 32 is saturated, so the counting circuit 32 needs to be turned off.

[0149] It should be noted that the embodiment is not limited to the counting mode, and both asynchronous counting mode and synchronous counting mode are possible, that is, the plurality of registers 3211 can form a traveling wave asynchronous counting circuit or a synchronous counting circuit. Exemplarily, as shown in Figure 8 or Figure 9 , the counting circuit 32 is specifically a traveling wave asynchronous counting circuit.

[0150] It should be noted that the Q end signal of the register D MSB serves as an overflow flag, that is, after the Q end signal of the register D MSB is flipped to "1", it can be used as an overflow flag to make the counting circuit 32 stop working; in addition, it can also turn off the enable signal of the quenching module 322, so that the SPAD pixel no longer generates an avalanche event.

[0151] In the embodiment of the present disclosure, since the exposure enable signal and the overflow flag can cause the quenching module 322 to be closed in some cases, the exposure enable signal and the overflow flag can be operated by a logic circuit to output a quenching enable signal to the quenching module 322, and the quenching enable signal makes the quenching module 322 work according to the following requirements:

[0152] Under the premise that the exposure enable signal is valid: when the overflow flag is valid (the Q end signal of the register D MSB outputs "1"), the quenching enable signal is invalid, and the quenching module 322 is closed; when the overflow flag is invalid (the Q end signal of the register D MSB outputs "0"), the quenching enable signal is valid, and the quenching module 322 can quench the SPAD pixel;

[0153] Under the premise that the exposure enable signal is invalid: whether the overflow flag is valid or invalid, the quenching enable signal is invalid, and the quenching module 322 is closed.

[0154] It should be noted that the exposure enable signal is valid, which means that the SPAD pixel in the pixel array 21 is in an exposure state and can respond to photons; the quenching enable signal is valid, which means that the quenching module 322 can quench the SPAD pixel and output a pulse signal.

[0155] Specifically, as shown in Figure 8 orFigure 9 As shown in the figure, a quenching-off module 51 connected with the Q end of the register D MSB is arranged at the input end of the quenching module 322, and a counting-off module 52 connected with the register D LSB is arranged at the output end of the quenching module 322. The quenching-off module 51 and the counting-off module 52 are both circuits composed of logic gates, and the logic gate of the quenching-off module 51 can make the quenching module 322 work according to the above requirements, and the specific logic of the embodiment is not limited.

[0156] The input end of the counting-off module 52 is connected with the output end of the quenching module 322 and the Q end of the register D MSB , and the output end of the counting-off module 52 is connected with the clock end of the register D LSB . The logic gate of the counting-off module 52 can make the counter work according to the following requirements:

[0157] On the premise that the overflow flag is invalid (the Q end of the register D MSB outputs “0”), when the quenching module 322 outputs a pulse signal, the counter 321 counts once;

[0158] On the premise that the overflow flag is valid (the Q end of the register D MSB outputs “1”), whether the quenching module 322 outputs a pulse signal or not, the counter 321 does not count.

[0159] It should be further pointed out that, Figure 9 The corresponding logic gates in the quenching-off module 51 and the counting-off module 52 shown in the figure are only examples, and can be selected according to actual conditions, and no specific limitation is made.

[0160] The embodiments of the present disclosure effectively reduce the problem of excessively high working power consumption of the SPAD-based PCI image sensor when the resolution is increased or the light intensity is too strong through two schemes. On the one hand, the incident light intensity is dynamically and real-timely judged, when the light intensity is too strong, the dead time of the SPAD pixel is adjusted, the photon counting rate is reduced, and the photon counting value in the exposure time is lowered. In this way, not only the overall power consumption can be reduced, but also the transient power consumption is reduced due to the decrease of the photon counting rate. On the other hand, the structure of the counting circuit 32 is improved, the last register D MSB in the counting circuit 32 is used as an overflow protection register, and the Q end signal of the overflow protection register D MSB is used to close the counting circuit 32 after the counting circuit 32 reaches saturation, specifically, the quenching module 322 is closed, so that the SPAD pixel no longer undergoes the avalanche and counting process (i.e., the processes (1) and (2) described above), and the power consumption waste after the saturation of the counting circuit 32 is avoided.

[0161] It should be noted that the two schemes can be used simultaneously, and are applicable to pixel array 21 of any size, and are applicable to synchronous counting mode or asynchronous counting mode, and are not specifically limited in this regard. In summary, the two schemes do not require additional low-power design overhead, and are automatically run in real time during imaging, which can reduce the power consumption of imaging device 20.

[0162] In yet another embodiment of the present disclosure, referring to Figure 10 which shows a schematic diagram of the constituent structure of an imaging device provided by an embodiment of the present disclosure. As shown in Figure 10 , the imaging device 20 comprises a pixel array 21 composed of a plurality of SPAD pixels and the aforementioned circuit 30 for reducing the power consumption of the imaging device.

[0163] In which the imaging device 20 applies the method for reducing the power consumption of the imaging device as described above

[0164] In the embodiment of the present disclosure, for the imaging device 20, since it comprises the aforementioned circuit 30, it at least has the same advantages as the circuit 30, which can reduce the power consumption of the imaging device 20 and make the imaging device 20 work normally.

[0165] For details not disclosed in the embodiments of the present disclosure, reference can be made to the description of the foregoing embodiments.

[0166] The above is only a preferred embodiment of the present disclosure, and is not intended to limit the protection scope of the present disclosure.

[0167] It should be noted that in the present disclosure, the terms "comprise", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "comprises a" does not exclude the presence of another identical element in the process, method, article or device comprising the element.

[0168] The above-mentioned serial numbers of the embodiments of the present disclosure are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0169] The methods disclosed in the several method embodiments provided by the present disclosure can be combined arbitrarily without conflict to obtain new method embodiments.

[0170] The features disclosed in the several product embodiments provided by the present disclosure can be combined arbitrarily without conflict to obtain new product embodiments.

[0171] The features disclosed in several method or device embodiments of the present disclosure can be arbitrarily combined, without conflict, to form new method embodiments or device embodiments.

[0172] The above description is merely a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present disclosure, and all such changes or replacements should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A method for reducing the power consumption of an imaging device, characterized in that, The imaging device includes at least a pixel array composed of multiple SPAD pixels; the method includes: Acquire light intensity information and / or counting information, wherein the light intensity information includes light intensity parameters or a first type of photon count value of the SPAD pixel in the pixel array, and the counting information includes a second type of photon count value of the SPAD pixel in the pixel array; wherein the first type of photon count value is related to the ambient light intensity, and the second type of photon count value is related to the imaging target; The imaging conditions are determined based on the light intensity information or the counting information, and the photon counting rate of the SPAD pixels in the pixel array is adjusted according to the determination result. The imaging conditions are determined based on the light intensity information, and the photon count rate of the SPAD pixels in the pixel array is adjusted according to the determination result, including: The light intensity parameter is compared with at least one light intensity threshold. If the light intensity parameter is greater than or equal to the light intensity threshold, the photon count rate of the SPAD pixel in the pixel array is reduced; if the light intensity parameter is less than the light intensity threshold, the photon count rate of the SPAD pixel in the pixel array is increased. Alternatively, the first type of photon count value is compared with at least one judgment threshold. If the first type of photon count value is greater than or equal to the judgment threshold, the photon count rate of the SPAD pixel in the pixel array is reduced; if the first type of photon count value is less than the judgment threshold, the photon count rate of the SPAD pixel in the pixel array is increased. Alternatively, the imaging conditions are determined based on the counting information, and the photon counting rate of the SPAD pixels in the pixel array is adjusted according to the determination result, including: The second type of photon count value is compared with the count threshold. If the second type of photon count value is equal to the count threshold, the photon count rate of the SPAD pixel in the pixel array is reduced to 0.

2. The method according to claim 1, characterized in that, The counting information is used to determine the imaging conditions and to image the target; the light intensity information and the counting information are obtained in the same frame or different frames.

3. The method according to claim 2, characterized in that, When the light intensity information and the counting information are acquired in different frames, the SPAD pixel used to acquire the first type of photon count value and the second type of photon count value are the same, and the light intensity information is acquired in the previous frame and the counting information is acquired in the next frame.

4. The method according to claim 2, characterized in that, When the light intensity information and the counting information are acquired in the same frame, the SPAD pixel used to acquire the first type of photon count value is different from the one used to acquire the second type of photon count value, and the light intensity information and the counting information are acquired simultaneously.

5. The method according to claim 1, characterized in that, When determining the imaging conditions based on the light intensity information, and adjusting the photon count rate of the SPAD pixels in the pixel array based on the determination result: Increasing the photon count rate of the SPAD pixels in the pixel array includes: Reduce the dead time of the SPAD pixels in the pixel array; Lowering the photon count rate of the SPAD pixels in the pixel array includes: Increase the dead time of the SPAD pixels in the pixel array.

6. The method according to claim 1, characterized in that, The first type of photon count value includes the sum, average, or median of the photon count values ​​of the SPAD pixels in the pixel array.

7. A circuit for reducing the power consumption of an imaging device, characterized in that, The imaging device includes at least a pixel array composed of multiple SPAD pixels; the circuit includes an acquisition circuit, a counting circuit, and an adjustment circuit; wherein: The acquisition circuit is used to acquire light intensity information, which includes light intensity parameters or the first type of photon count value of the SPAD pixel in the pixel array, and the first type of photon count value is related to the ambient light intensity. The counting circuit is used to acquire counting information, which includes the second type of photon count value of the SPAD pixel in the pixel array, and the second type of photon count value is related to the imaging target. The adjustment circuit is used to determine the imaging conditions based on the light intensity information or the counting information, and adjust the photon counting rate of the SPAD pixels in the pixel array according to the determination result. The adjustment circuit is further configured to compare the light intensity parameter with at least one light intensity threshold; if the light intensity parameter is greater than or equal to the light intensity threshold, reduce the photon count rate of the SPAD pixel in the pixel array; if the light intensity parameter is less than the light intensity threshold, increase the photon count rate of the SPAD pixel in the pixel array; or, compare the first type of photon count value with at least one judgment threshold; if the first type of photon count value is greater than or equal to the judgment threshold, reduce the photon count rate of the SPAD pixel in the pixel array; if the first type of photon count value is less than the judgment threshold, increase the photon count rate of the SPAD pixel in the pixel array; or, compare the second type of photon count value with a counting threshold; if the second type of photon count value is equal to the counting threshold, reduce the photon count rate of the SPAD pixel in the pixel array to 0.

Images