Receiving device for direct time-of-flight ranging

Abstract

The utility model provides a receiving device for direct time-of-flight distance measurement, and the device is characterized in that the device comprises a photosensitive array which comprises at least two photosensitive units, and the at least two photosensitive units comprise a first photosensitive unit and a second photosensitive unit; the reading circuit comprises a first time-to-digital converter TDC and a second TDC, the signal output end of the first photosensitive unit is connected to the input end of the first TDC, and the signal output end of the second photosensitive unit is connected to the input end of the second TDC.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of ranging technology, and more particularly, to a receiving device, method and system for direct time of flight ranging. BACKGROUND

[0002] Direct-Time of Flight (DToF) ranging is a ranging technology in the field of 3D image sensing. A DToF ranging device mainly includes a transmitting end Tx and a receiving end Rx. Generally, the DToF ranging process is as follows: the transmitting end sends a laser pulse to a to-be-measured object, the photons reflected by the to-be-measured object back to the receiving end generate an electrical signal after responding to a SPAD (Single Photon Avalanche Diode) photosensitive unit, and then the electrical signal is converted into the time of arrival of the photons by a TDC (Time Digital Converter), thereby completing the recording of one avalanche event. After repeating the pulse transmission multiple times, a histogram of the number of avalanche events occurring at different times within the pulse period can be drawn, and then the distance of the to-be-measured object can be calculated. However, the current DToF technology has a peak front-leaning phenomenon (also known as pile-up phenomenon), especially when the distance of the measured object is too close or the reflectivity is too high, the reflected light energy is too strong, the peak front-leaning phenomenon is serious, and even the peak saturation problem occurs, which seriously affects the ranging accuracy.

[0003] Therefore, there is a need for a method, system and device capable of effectively increasing the dynamic range of DToF ranging and improving the ranging accuracy. UTILITY MODEL CONTENT

[0004] Embodiments of the present disclosure provide a receiving device for direct time of flight ranging, characterized in that the receiving device comprises: a photosensitive array comprising at least two photosensitive units, the at least two photosensitive units comprising a first photosensitive unit and a second photosensitive unit; and a readout circuit comprising a first time-to-digital converter (TDC) and a second TDC, wherein a signal output end of the first photosensitive unit is connected to an input end of the first TDC, and a signal output end of the second photosensitive unit is connected to an input end of the second TDC.

[0005] According to embodiments of the present disclosure, the signal output end of the second photosensitive unit is separately connected to the input end of the second TDC, and the signal output ends of all photosensitive units in the photosensitive array except the second photosensitive unit are commonly connected to the input end of the first TDC through an OR gate.

[0006] According to embodiments of the present disclosure, the photosensitive array comprises N 2 photosensitive units, and the N 2The second photosensitive unit is any one of the N photosensitive units. 2 The second photosensitive unit is any one of the N photosensitive units.

[0007] According to an embodiment of the present disclosure, the photosensitive array includes two photosensitive units, wherein a photon detection efficiency PDE of the first photosensitive unit is greater than a PDE of the second photosensitive unit.

[0008] According to an embodiment of the present disclosure, signal output ends of all photosensitive units in the photosensitive array are commonly connected to an input end of the first TDC through an OR gate; and the signal output ends of all photosensitive units in the photosensitive array are commonly connected to an input end of the second TDC through an AND gate.

[0009] According to an embodiment of the present disclosure, the photosensitive unit is a single-photon avalanche diode SPAD photosensitive unit.

[0010] According to an embodiment of the present disclosure, the receiving device further includes a control circuit connected to the photosensitive array and configured to control operation of the photosensitive array.

[0011] According to an embodiment of the present disclosure, the receiving device further includes a first counting circuit connected to an output end of the first TDC and configured to statistically count output signals of the first TDC in a predetermined time interval to generate a first histogram; and a second counting circuit connected to an output end of the second TDC and configured to statistically count output signals of the second TDC in the predetermined time interval to generate a second histogram.

[0012] According to an embodiment of the present disclosure, the receiving device further includes a selection circuit connected to the first counting circuit and the second counting circuit and configured to select one of the first histogram and the second histogram as an output histogram based on a preset rule.

[0013] According to an embodiment of the present disclosure, the preset rule includes at least one of the following: in a case where positions of peaks of the first histogram and the second histogram in time are different, selecting one of the first histogram and the second histogram with a later peak in time as the output histogram; in a case where a difference between a total number of samples of the first histogram and a total number of samples of the second histogram is greater than a preset threshold, selecting one of the first histogram and the second histogram with a greater total number of samples as the output histogram; and selecting one of the first histogram and the second histogram with a peak sample number closer to an expected peak sample number as the output histogram, wherein the expected peak sample number is determined based on a total number of pulses emitted by a transmitting end.

[0014] Embodiments of the present disclosure can provide a method, system and device capable of effectively increasing the dynamic range of DToF ranging and improving ranging accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0015] The above and other aspects, features and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0016] Figure 1a A structural schematic diagram of a receiving device 100 for DToF ranging according to embodiments of the present disclosure is shown;

[0017] Figure 1b A circuit connection manner between a SPAD photosensitive array 102 and a TDC in a SPAD readout circuit 104 according to embodiments of the present disclosure is shown;

[0018] Figure 1c A schematic diagram of a receiving device 150 for direct time-of-flight ranging according to embodiments of the present disclosure is shown;

[0019] Figure 2a A histogram of TDC1 under strong reflected light according to embodiments of the present disclosure is shown;

[0020] Figure 2b A histogram of TDC2 under strong reflected light according to embodiments of the present disclosure is shown;

[0021] Figure 3a A histogram of TDC1 under weak reflected light according to embodiments of the present disclosure is shown;

[0022] Figure 3b A histogram of TDC2 under weak reflected light according to embodiments of the present disclosure is shown;

[0023] Figure 4a A structural schematic diagram of a receiving device for DToF ranging according to embodiments of the present disclosure is shown;

[0024] Figure 4b A circuit connection manner between a SPAD photosensitive array and a TDC in a SPAD readout circuit according to embodiments of the present disclosure is shown;

[0025] Figure 5a A histogram of TDC1 under strong reflected light according to embodiments of the present disclosure is shown;

[0026] Figure 5b A histogram of TDC2 under strong reflected light according to embodiments of the present disclosure is shown;

[0027] Figure 6aA histogram of TDC1 under weak reflected light is shown according to an embodiment of the present disclosure;

[0028] Figure 6b A histogram of TDC2 under weak reflected light is shown according to an embodiment of the present disclosure;

[0029] Figure 7a A structural schematic diagram of a receiving device for DToF ranging is shown according to an embodiment of the present disclosure;

[0030] Figure 7b A circuit connection manner between a SPAD light sensing array and a TDC in a SPAD readout circuit is shown according to an embodiment of the present disclosure;

[0031] Figure 8a A histogram of TDC1 under strong reflected light is shown according to an embodiment of the present disclosure;

[0032] Figure 8b A histogram of TDC2 under strong reflected light is shown according to an embodiment of the present disclosure;

[0033] Figure 9a A histogram of TDC1 under weak reflected light is shown according to an embodiment of the present disclosure; and

[0034] Figure 9b A histogram of TDC2 under weak reflected light is shown according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] Before undertaking a review of the detailed description provided below, it can be advantageous to set forth definitions of certain words and phrases which have been used throughout this patent document. The term “couple” and variations thereof, when used in this patent document, mean to connect or link one or more elements together or with at least one other element. The terms “transmit,” “receive,” and “communicate,” as well as derivatives thereof, encompass both direct and indirect communication or exchange of information, whether through direct physical connections, wireless connections, or the like. The term “include” and variations thereof, means to comprise but not to be limited to, and is intended to cover a non-exclusive inclusion. The term “or” is inclusive, meaning and / or. The phrase “associated with,” the phrase “associated with” and variations thereof, as well as the phrase “associated therewith,” means to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, be proximate to, be bound to or with, have a property of, have relations with, or the like. The term “controller” means any device, system or part thereof that controls at least one operation. Such a controller can be implemented in hardware or a combination of hardware and software and / or firmware. The functionality associated with any particular controller can be centralized or distributed, whether locally or remotely. The phrase “at least one of,” when used with a list of items, means that different combinations of one or more of the listed items can be utilized and only one item from the list can be needed. For example, “at least one of A, B, and C” includes any of the following combinations: A, B, C, A and B, A and C, B and C, A and B and C.

[0036] Definitions for other certain words and phrases are provided throughout this patent document. Those of ordinary skill in the art will understand that in many, if not most instances, such definitions apply to prior and future uses of such defined words and phrases.

[0037] In this patent document, the terms module, application component, and division hierarchy of sub-modules are used to describe an arrangement of components, and are merely used to facilitate description of embodiments, and are not intended to limit the scope of the disclosure. Embodiments of the disclosure can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure will be thorough and complete and will fully convey the inventive idea to those skilled in the art. Embodiments of the disclosure can be combined to form additional embodiments.

[0038] The disclosure will be described in detail below with reference to the examples of the exemplary embodiments of the disclosure. However, the disclosure is not limited to the embodiments described herein, which can be implemented in many different forms. The described embodiments are merely used to make the disclosure thorough and complete and to fully convey the inventive idea to those skilled in the art. The features of the described various embodiments can be combined with or replaced by each other, unless explicitly excluded or should be excluded according to the context.

[0039] Generally, the DToF ranging process is as follows: the transmitting end sends a laser pulse to the object to be measured, the photons reflected by the object to be measured back to the receiving end generate an electrical signal after being responded by a SPAD (Single Photon Avalanche Diode) photosensitive unit, and then the time of arrival of the photons is converted into time by a TDC (Time Digital Converter), thereby completing the recording of an avalanche event. After repeating the pulse transmission multiple times, a histogram of the number of avalanche events at different times within the pulse period can be drawn, and the distance of the object to be measured can be calculated.

[0040] When a SPAD responds to a photon and triggers an avalanche effect, the time required for the SPAD to return from the avalanche state to the initial state is called the dead time. In some cases, due to the dead time, the photons arriving during the dead time cannot be responded to, resulting in a histogram waveform obtained by measurement compared with the original laser pulse waveform, and a phenomenon of peak front tilting (also known as pile-up phenomenon). When the distance of the object to be measured is too close or the reflectivity is too high, the reflected light energy is too strong, the peak front tilting phenomenon is serious, and even the peak saturation problem occurs, which seriously affects the ranging accuracy. In this article, the peak front tilting phenomenon can refer to a phenomenon that the peak of the histogram waveform obtained by measurement is earlier in time than the peak of the original laser pulse waveform or the actual pulse waveform peak.

[0041] In addition, in some cases, the time of flight of the reflected light of a close-range object is short, and the reflected light of a close-range object is received before the exposure of the receiving end, and the reflected light of a long-distance object is received in the latter half. Therefore, the entire detection period can be divided into n sub-periods, different exposure durations are set for different sub-periods, and the total exposure duration of a long-distance object is greater than that of a close-range object, so as to ensure the long-distance measurement accuracy while preventing close-range overexposure, thereby improving the dynamic range of DToF ranging.

[0042] However, the current method does not consider the influence of the pile-up phenomenon under different reflected light intensities, and the measurement error is large when the distance of the object to be measured is too close or the reflectivity is too high. In addition, some current methods for ensuring the measurement accuracy of close-range and high-reflectivity objects can cause the number of photons returned by a long-distance or low-reflectivity object to be insufficient, thereby causing the histogram signal-to-noise ratio and the ranging accuracy to decrease. In addition, by dividing the measurement period to consider the reflected light intensity of the same object at different distances, the problem of different reflected light intensities of high-reflectivity and low-reflectivity objects at the same measurement distance cannot be solved.

[0043] Embodiments of the present disclosure provide a DToF ranging system receiving end design scheme that takes into account objects at different distances and with different reflectivity. By selecting, arranging, and designing the signal acquisition circuit of the SPAD light sensing unit, the measurement accuracy of objects at different distances and with different materials in the same field of view can be ensured, and the ranging dynamic range is further improved.

[0044] The DToF ranging system based on the SPAD sensor according to the embodiments of the present disclosure can include a controller, a light source emitting end, and a receiving end. In some embodiments, the receiving end (or receiving circuit or receiving device) can mainly include one or more of a SPAD light sensing array, a SPAD control circuit, and a SPAD readout circuit. The SPAD (Single Photon Avalanche Diode) is a kind of photoelectric device that receives a single photon to form an avalanche amplification to generate a signal count, and obtains the time of flight of the photon and the distance result through multiple repeated counts. In the present disclosure, at least two SPAD units are used to form a SPAD array as the receiving end of the DToF ranging system.

[0045] Specifically, Figure 1c A schematic diagram of a receiving device 150 for direct time-of-flight ranging according to an embodiment of the present disclosure is shown.

[0046] As Figure 1c shown, the receiving device 150 for direct time-of-flight ranging according to an embodiment of the present disclosure can include a light sensing array 151 and a readout circuit 152. The light sensing array 151 can include at least two light sensing units, for example, a first light sensing unit SPAD1 and a second light sensing unit SPAD2. The readout circuit 152 can include a first time-to-digital converter TDC (e.g., TDC1) and a second TDC (e.g., TDC2). In some embodiments, the signal output end of the first light sensing unit SPAD1 can be connected to the input end of the TDC1, and the signal output end of the second light sensing unit SPAD2 can be connected to the input end of the TDC2.

[0047] In some embodiments, the receiving device 150 can further include a control circuit. The control circuit can be connected to the light sensing array 151 and can be configured to control the operation of the light sensing array 151, for example, according to any existing and future methods required for the normal operation of the light sensing array 151 and any one or more light sensing units included in the light sensing array 151, which is not limited herein. In the following description, the control circuit is described as part of the receiving device according to the embodiments of the present disclosure. However, it should be understood that the receiving device according to the embodiments of the present disclosure can also not include the control circuit.

[0048] In some embodiments, the signal output end of the second light sensing unit SPAD2 can be individually connected to the input end of TDC2, and the signal output ends of all light sensing units (including SPAD1) in the light sensing array except the second light sensing unit SPAD2 can be collectively connected to the input end of TDC1 through an OR gate.

[0049] In some embodiments, further, the light sensing array 151 can include N 2 light sensing units, and the N 2 light sensing units can be arranged in an NxN array, where N is an integer greater than 1. In some implementations, the second light sensing unit SPAD2 can be any one of the N 2 light sensing units. In some implementations, the second light sensing unit SPAD2 can be the light sensing unit located at the center of the NxN array.

[0050] More specifically, Figure 1a A structural schematic diagram of a receiving device 100 for DToF ranging according to embodiments of the present disclosure is shown.

[0051] As Figure 1a shown, the receiving device 100 of the DToF ranging system can include a SPAD light sensing array 102, a SPAD control circuit 101, and a SPAD readout circuit 104. The SPAD light sensing array 102 can work under the control of the SPAD control circuit 101. When the SPAD receives a light signal to generate an avalanche current, the electrical signal can be processed by the SPAD readout circuit 104 and the time of flight can be calculated, and then the distance of the target object can be calculated.

[0052] As Figure 1a shown, the SPAD light sensing array 102 can include 9 small-size SPAD light sensing units 103 (e.g., SPAD1-SPAD9, arranged in a 3x3 array). The SPAD readout circuit 104 can include two time-to-digital converters (TDCs), e.g., TDC1 and TDC2. It should be understood that the number of light sensing units 9 or the 3x3 array in this embodiment is only an example, and the receiving device 100 according to embodiments of the present disclosure can also include any other number or any other arrangement (e.g., MxN, etc.) of light sensing units.

[0053] Figure 1b A circuit connection manner between the SPAD light sensing array 102 and the TDCs in the SPAD readout circuit 104 according to embodiments of the present disclosure is shown. As Figure 1bAs shown, SPAD5 (in other examples, it can also be any other non-array center photoreceptor unit) can be connected to TDC2 alone, and the output signals (i.e., signal output ends) of the remaining 8 SPADs can be connected together and connected to TDC1 after or operation (or) processing. The or operation (or) logic is: as long as any one of the 8 SPADs is triggered to generate avalanche current, the next avalanche event will be recorded, which can be equivalent to that the SPAD photosensitive area connected to TDC1 is 8 times that of TDC2.

[0054] When the target object is close or is a high-reflectivity material, the reflected light energy is strong. Since the SPAD photosensitive area connected to TDC1 is large, the cumulative histogram will produce a peak front-leaning phenomenon, and the ranging error is large, as shown in Figure 2a . While TDC2 is connected to only one small-size SPAD photoreceptor unit, the photosensitivity is low, and the cumulative histogram can still restore the light pulse waveform well, as shown in Figure 2b . At this time, the histogram of TDC2 can be selected for distance calculation.

[0055] When the target object is far away or is a low-reflectivity material, the reflected light energy is weak. Since the number of photons received by a single SPAD is insufficient, the cumulative histogram of TDC2 has a low signal-to-noise ratio and cannot completely restore the light signal waveform, as shown in Figure 3b . But the larger photosensitive area can increase the number of received photons, so the cumulative histogram of TDC1 restores the reflected light pulse waveform well, as shown in Figure 3a . At this time, the histogram of TDC1 can be selected for distance calculation.

[0056] At this point, the receiving end design can measure target objects of different distances and materials with high and low reflectivity, effectively solving the problems of peak front-leaning under strong reflected light and low signal-to-noise ratio under weak reflected light.

[0057] In some embodiments, the photosensitive array can include two photoreceptor units, a first photoreceptor unit SPAD1 and a second photoreceptor unit SPAD2, wherein the photon detection efficiency (PDE) of the first photoreceptor unit SPAD1 can be greater than the PDE of the second photoreceptor unit SPAD2.

[0058] More specifically, Figure 4a A structure schematic diagram of a receiving device 400 for DToF ranging according to an embodiment of the present disclosure is shown.

[0059] As Figure 4aAs shown, the receiving device 400 of the DToF ranging system can include a SPAD photosensitive array 402, a SPAD control circuit 401, and a SPAD readout circuit 405. The SPAD photosensitive array 402 can work under the control of the SPAD control circuit 401. When the SPAD receives a light signal to generate avalanche current, the electrical signal can be processed by the SPAD readout circuit 405 and the time of flight is calculated, and then the distance of the target object is calculated.

[0060] As shown, Figure 4a The SPAD photosensitive array 402 can include two SPAD photosensitive units SPAD1 and SPAD2 with different photo-detection efficiencies (PDEs). In one example, the PDE of the SPAD1 403 can be greater than the PDE of the SPAD2 404, that is, under the same light intensity, the SPAD1 403 is more likely to have an avalanche effect. The SPAD readout circuit 405 can include two time-to-digital converters (TDCs), for example, TDC1 and TDC2.

[0061] Figure 4b The circuit connection mode between the SPAD photosensitive array 402 and the TDC in the SPAD readout circuit 405 according to an embodiment of the present disclosure is shown. As shown, Figure 4b The SPAD1 can be connected to the TDC1, and the SPAD2 can be connected to the TDC2.

[0062] When the target object is close or is a high-reflectivity material, the reflected light energy is strong. Due to the high photo-detection efficiency of the SPAD1 403, the cumulative histogram will have a peak front-leaning phenomenon, and the ranging error is large, as shown in Figure 5a The photosensitivity of the SPAD2 404 is low, and the cumulative histogram can better restore the light pulse waveform, as shown in Figure 5b At this time, the histogram of the TDC2 can be selected for distance calculation.

[0063] When the target object is far away or is a low-reflectivity material, the reflected light energy is weak. At this time, the SPAD2 404 cannot accurately detect a small amount of photons, so the cumulative histogram of the TDC2 cannot record the light pulse waveform, as shown in Figure 6b But the SPAD1 403 has a strong photo-detection efficiency and can still respond to a small amount of photons, so the cumulative histogram of the TDC1 can record the reflected light pulse waveform, as shown in Figure 6a At this time, the histogram of the TDC1 can be selected for distance calculation.

[0064] At this time, the histogram of the TDC1 can be selected for distance calculation.

[0065] In some embodiments, the signal output ends of all the light sensing units in the light sensing array 151 can be commonly connected to the input end of TDC1 through an or gate; and the signal output ends of all the light sensing units in the light sensing array 151 can be commonly connected to the input end of TDC2 through an and gate.

[0066] More specifically, Figure 7a A structural schematic diagram of a receiving device 700 for DToF ranging is shown according to an embodiment of the present disclosure.

[0067] As Figure 7a shown, the receiving device 700 of the DToF ranging system can include a SPAD light sensing array 702, a SPAD control circuit 701 and a SPAD readout circuit 704. The SPAD light sensing array 702 can work under the control of the SPAD control circuit 701. When the SPAD receives a light signal to generate an avalanche current, the electrical signal can be processed by the SPAD readout circuit 704 and the time of flight can be calculated, and then the distance of the target object can be calculated.

[0068] As Figure 7a shown, the SPAD light sensing array 702 can include 3 SPAD light sensing units 703 (e.g., SPAD1, SPAD2 and SPAD3) of the same size, and the SPAD readout circuit 704 can include two time-to-digital converters (TDCs), e.g., TDC1 and TDC2. It should be understood that the number 3 of light sensing units in this embodiment is only an example, and the receiving device 700 according to an embodiment of the present disclosure can also include any other number of light sensing units.

[0069] Figure 7b A circuit connection mode between the SPAD light sensing array 702 and the TDCs in the SPAD readout circuit 704 is shown according to an embodiment of the present disclosure. As Figure 7b shown, the output signals (i.e., signal output ends) of SPAD1, SPAD2 and SPAD3 can be connected together and divided into two paths for subsequent operation, e.g., one path can be connected to TDC1 through or operation, and the other path can be connected to TDC2 through and operation. The or operation (or) logic is that any one of the 3 SPADs is triggered to generate an avalanche current, and the next avalanche event will be recorded. The and operation (and) logic is that only when the 3 SPADs are triggered at the same time, the next avalanche event will be recorded.

[0070] When the distance of the target object is close or the material is high reflectivity, the reflected light energy is strong, and since any one of the SPADs connected to TDC1 is triggered to output an event, the cumulative histogram is more likely to produce a peak front leaning phenomenon, and the ranging error is large, asFigure 8a As shown. And TDC2 needs 3 SPADs connected to be triggered at the same time to output a count, which is equivalent to reducing the trigger probability, so the histogram accumulated by TDC2 can better restore the light pulse waveform, as shown. Figure 8b At this time, the histogram of TDC2 can be selected for distance calculation.

[0071] When the target object is far away or is a low reflectivity material, the reflected light energy is weak, and the trigger probability of a single SPAD is low, and the trigger probability of 3 SPADs is lower, so the histogram accumulated by TDC2 cannot completely restore the light signal waveform, as shown. Figure 9b But any one of the three SPADs triggers can count, which is equivalent to three times the trigger probability, so the histogram accumulated by TDC1 restores the reflected light pulse waveform better, as shown. Figure 9a At this time, the histogram of TDC1 can be selected for distance calculation.

[0072] At this time, the histogram of TDC1 can be selected for distance calculation.

[0073] In some embodiments, the light sensing unit included in the light sensing array according to the embodiments of the present disclosure can be a SPAD light sensing unit, as described above.

[0074] In some embodiments, one or more of the receiving device 150, the receiving device 100, the receiving device 400, and the receiving device 700 according to the embodiments of the present disclosure can further include a first counting circuit and a second counting circuit. The first counting circuit can be connected to the output end of the first TDC, and can be configured to statistically count the output signal of the first TDC in a predetermined time interval to generate a first histogram (for example, as shown in Figure 2a , Figure 3a , Figure 5a , Figure 6a , Figure 8a and Figure 9a , etc.). The second counting circuit can be connected to the output end of the second TDC, and can be configured to statistically count the output signal of the second TDC in a predetermined time interval to generate a second histogram (for example, as shown in Figure 2b , Figure 3b , Figure 5b , Figure 6b , Figure 8b and Figure 9b , etc.). The predetermined time interval can be the preset statistical interval of the histogram as shown.

[0075] In some embodiments, one or more of the receiving apparatus 150, the receiving apparatus 100, the receiving apparatus 400, and the receiving apparatus 700 according to embodiments of the present disclosure can further include a selection circuit. The selection circuit can be connected to the first counting circuit and the second counting circuit, and can be configured to select one of the first histogram generated according to the first counting circuit and the second histogram generated according to the second counting circuit as the final output histogram based on a preset rule.

[0076] In some embodiments, the preset rule described above can include at least one of the following:

[0077] In the case where the positions of the peak values of the first histogram and the second histogram in time are different, the one of the first histogram and the second histogram with the peak value later in time is selected as the output histogram. For example, as shown in Figure 2a and Figure 2b , when the peak value of the first histogram (e.g., 1001) generated according to the first counting circuit is earlier in time than the peak value of the second histogram (e.g., 1002) generated according to the second counting circuit, it can be considered that the first histogram (e.g., 1001) has a peak value front-leaning phenomenon, and the ranging error is large, so the second histogram (e.g., 1002) with the peak value later in time can be selected as the final output histogram for distance calculation of the object to be measured. Figure 2a Figure 2b Figure 2a Figure 2b

[0078] In the case where the difference between the total number of samples of the first histogram and the total number of samples of the second histogram is greater than a preset threshold, the one of the first histogram and the second histogram with the greater total number of samples is selected as the output histogram. For example, as shown in Figure 3a and Figure 3b , when the total number of samples included in the first histogram (e.g., 1001) generated according to the first counting circuit is greater than the total number of samples included in the second histogram (e.g., 1002) generated according to the second counting circuit by a preset threshold number, it can be considered that the number of received photons in the second histogram (e.g., 1002) is insufficient, and the signal-to-noise ratio of the accumulated histogram is low, so the first histogram (e.g., 1001) with the greater total number of samples can be selected as the final output histogram for distance calculation of the object to be measured. The preset threshold number (e.g., any integer greater than or equal to 0) described herein can be set by experience or based on any existing or future mathematical method depending on the actual application scenario, which is not limited herein. Figure 3a Figure 3b Figure 3b Figure 3a

[0079] ​​​​​​​​In some embodiments, the preset rule described above can include selecting one of the first histogram and the second histogram that has a peak closer to an expected peak as the output histogram. For example, one of the first histogram and the second histogram that has a number of samples in a peak interval (i.e., a peak sample number) closer to an expected peak sample number can be selected as the output histogram. In this context, the peak interval of a histogram can refer to a statistical interval in which the number of samples is the largest in the histogram. In some embodiments, the expected peak can be determined based on a total number of pulses transmitted by the transmitting end. For example, in a case where the total number of pulses transmitted by the transmitting end is N, the expected peak can be determined as N / 5, and the like. The value N / 5 here is merely an example, and the application can also determine the expected peak based on any other specific value, or according to an empirically determined ratio of the peak sample number to the total number of transmitted pulses.

[0080] It should be understood that one or more of the receiving apparatus 150, the receiving apparatus 100, the receiving apparatus 400, and the receiving apparatus 700 described above are merely illustrative, and a receiving apparatus according to embodiments of the present disclosure can also include any other device(s) than those included in one or more of the receiving apparatus 150, the receiving apparatus 100, the receiving apparatus 400, and the receiving apparatus 700, or omit or replace any device(s) in one or more of the receiving apparatus 150, the receiving apparatus 100, the receiving apparatus 400, and the receiving apparatus 700, without limitation herein. In addition, embodiments of the present disclosure can also include any implementation method or operation method (and computer storage medium recording instructions for implementing these methods) of one or more of the receiving apparatus 150, the receiving apparatus 100, the receiving apparatus 400, and the receiving apparatus 700 described above, as well as any circuitry including one or more of the receiving apparatus 150, the receiving apparatus 100, the receiving apparatus 400, and the receiving apparatus 700, for example, a DToF ranging system including a receiving apparatus, a controller, and a light transmitting end according to embodiments of the present disclosure.

[0081] The entire hardware computing apparatus described in the present disclosure or a component thereof can be implemented by various suitable hardware means, including but not limited to FPGA, ASIC, SoC, discrete gate or transistor logic, discrete hardware components, or any combination thereof.

[0082] The block diagrams of the circuits, devices, apparatuses, equipment, systems involved in the present disclosure are merely exemplary examples and are not intended to require or imply a connection, arrangement, configuration as shown in the block diagrams. As those skilled in the art will recognize, these circuits, devices, apparatuses, equipment, systems can be connected, arranged, configured in any manner as long as the desired purpose can be achieved.

[0083] While the present disclosure has been described with an example embodiment, various changes and modifications can be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.

[0084] No description in the present disclosure should be interpreted as implying any particular element, step or function is an essential element. The scope of the patent subject matter is defined only by the claims.

[0085] Example embodiments according to the present disclosure have been disclosed herein, and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation. In some instances, features, characteristics, and / or elements described in connection with a particular embodiment can be used alone or in combination with features, characteristics, and / or elements described in connection with other embodiments, unless otherwise specifically indicated. Accordingly, one of ordinary skill in the art will recognize that various changes and modifications of the example embodiments can be made without departing from the spirit and scope of the claims.

Claims

1. A receiving device for direct time-of-flight ranging, characterized by The receiving device comprises: a photosensitive array comprising at least two photosensitive units, the at least two photosensitive units comprising a first photosensitive unit and a second photosensitive unit; a readout circuit comprising a first time-to-digital converter (TDC) and a second TDC, wherein a signal output end of the first photosensitive unit is connected to an input end of the first TDC, and a signal output end of the second photosensitive unit is connected to an input end of the second TDC.

2. The receiving device of claim 1, wherein the signal output end of the second photosensitive unit is separately connected to the input end of the second TDC, and signal output ends of all photosensitive units in the photosensitive array except the second photosensitive unit are collectively connected to the input end of the first TDC through an OR gate.

3. The receiving device of claim 2, wherein The photosensitive array includes N 2 One photosensitive unit, the N 2 The photosensitive units are arranged in an NxN array, where N is an integer greater than 1. The second light sensing unit is any one of the N light sensing units. 2 ​ 4. The receiving device of claim 1, wherein the photosensitive array comprises two photosensitive units, wherein a photon detection efficiency (PDE) of the first photosensitive unit is greater than a PDE of the second photosensitive unit.

5. The receiving device of claim 1, wherein signal output ends of all photosensitive units in the photosensitive array are collectively connected to the input end of the first TDC through an OR gate; and signal output ends of all photosensitive units in the photosensitive array are collectively connected to the input end of the second TDC through an AND gate.

6. The receiving device of claim 1, wherein the photosensitive units are single-photon avalanche diode (SPAD) photosensitive units.

7. The receiving device of claim 1, wherein the receiving device further comprises a control circuit connected to the photosensitive array and configured to control operation of the photosensitive array.

8. The reception apparatus according to claim 1, characterized by The receiving device further comprises: a first counting circuit connected to an output end of the first TDC and configured to statistically count output signals of the first TDC in a predetermined time interval to generate a first histogram; and a second counting circuit connected to an output end of the second TDC and configured to statistically count output signals of the second TDC in the predetermined time interval to generate a second histogram.

9. The receiving apparatus of claim 8, wherein, The receiving device further comprises: a selection circuit connected to the first counting circuit and the second counting circuit and configured to select one of the first histogram and the second histogram as an output histogram based on a preset rule.

10. The receiving apparatus of claim 9, wherein The preset rule comprises at least one of: in a case where a peak value of the first histogram and a peak value of the second histogram are different in time, selecting one of the first histogram and the second histogram with a later peak value in time as the output histogram; in a case where a difference between a total number of samples of the first histogram and a total number of samples of the second histogram is greater than a preset threshold, selecting one of the first histogram and the second histogram with a greater total number of samples as the output histogram; selecting as the output histogram one of the first histogram and the second histogram that has a number of peak samples closer to an expected number of peak samples, wherein the expected number of peak samples is determined based on a total number of pulses transmitted by a transmitting end.

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