A DTOF imaging system

Abstract

The application discloses a DTOF imaging system, comprising a large-array DTOF chip system, a laser, a transmitting optical system and a receiving optical system; a laser driving module sends a light driving signal to control the laser to light up in the presence of a first period delay of a measurement pulse; a SPAD control module generates a SPAD enable signal to control the preset row SPAD pixel unit to open in the presence of a second period delay of the measurement pulse; a pulse control module generates a timing start signal to send to a TDC array in the presence of a third period delay of the measurement pulse; a TDC control module sends a TDC enable signal to control each row of TDC units to open; the OA path from the pulse control module to the laser driving module and the OB path from the pulse control module to the TDC array are path delayed in time sequence, and are the same under different temperatures and / or different voltages. Through the above structure, the tof value measurement stability and accuracy under temperature and voltage fluctuation are improved.

Description

Technical Field

[0001] This invention relates to the technical field of DTOF imaging, and more particularly to a DTOF imaging system. Background Technology

[0002] Imaging systems based on Direct Time of Flight (DTOF) technology have advantages such as high accuracy, long ranging range, and strong anti-interference ability, and are widely used in fields such as autonomous driving, industrial manufacturing, and smart homes.

[0003] Traditional DTOF imaging systems such as Figure 1 As shown, the system includes a lighting control module, a laser drive module, a laser, a transmitting optical system, a receiving optical system, SPAD pixel units, a TDC module, and a data processing module. However, with today's demand for high resolution, the number of SPAD pixel units and TDC modules has increased dramatically for large-area DTOF imaging systems. Simply replicating SPAD pixel units and TDC modules to design a large-area DTOF imaging system would result in excessive hardware resource consumption, and the system's area and power consumption would not be effectively controlled. This would lead to excessive resource consumption and reduced measurement speed in large-area DTOF imaging systems.

[0004] Furthermore, since DTOF imaging systems calculate distance by measuring the time interval between light emission and reception, the stability requirements for the time difference between the laser beam emission and the start of counting by the TDC module are very stringent. With increasing demands for measurement accuracy, circuit delays in large-area DTOF systems also need to be considered. In particular, circuit delays vary with temperature and voltage, causing changes in the delays of the illumination signal path from the illumination control module to the laser and the TDC timing start signal path from the illumination control module to the TDC module. These changes affect the TDC quantization results, consequently impacting the accuracy and stability of the final measured TOF value, and ultimately affecting the measurement outcome. Summary of the Invention

[0005] This invention provides a DTOF imaging system that balances resource consumption and measurement speed while avoiding the influence of temperature and voltage on measurement results, thereby improving the accuracy and stability of the measured TOF values ​​under different temperatures and voltage fluctuations.

[0006] According to one aspect of the present invention, a DTOF imaging system is provided, comprising a large-area DTOF chip system, a laser, a transmitting optical system, and a receiving optical system;

[0007] The large-area DTOF chip system includes a pulse control module, a lighting control module, a laser drive module, a SPAD pixel array, a SPAD control module, a TDC array, a TDC control module, and a data processing module;

[0008] The SPAD pixel array comprises multiple SPAD pixel units arranged in an m*n array, and the TDC array comprises multiple TDC units arranged in an m*i array; where m, n, and i are all positive integers, and i <n;

[0009] The working process of a DTOF imaging system consists of multiple working frames, and each working frame includes multiple subframes.

[0010] In each subframe, the pulse control module is used to control the generation of multiple measurement pulses according to a preset number of pulses and a preset pulse interval, and to generate a laser enable signal laser_en directly or indirectly based on each measurement pulse; the illumination control module is used to generate an illumination trigger signal trig_group directly or indirectly based on the laser enable signal laser_en; the laser drive module is used to send an illumination drive signal tx_trig based on the illumination trigger signal trig_group, so as to control the laser to light up in the current subframe during the time when there is a first cycle delay relative to the measurement pulse;

[0011] The transmitting optical system is used to project the light pulse emitted by the laser onto the target object in each subframe. After being reflected by the target object, the light pulse is then transmitted through the receiving optical system to the SPAD pixel unit in the preset row corresponding to the current subframe.

[0012] In each subframe, the pulse control module is also used to generate a SPAD enable signal `spad_pulse` based on the measurement pulse; the SPAD control module is used to directly or indirectly generate a SPAD enable signal `spad_en` based on the `spad_pulse`, so as to control the SPAD pixel units in the SPAD pixel array corresponding to the current subframe to be enabled during a second period delay relative to the measurement pulse; wherein, SPAD pixel units in different preset rows of the SPAD pixel array are enabled in different subframes; the SPAD pixel units are used to collect light pulses and generate electrical signals;

[0013] In each subframe, the pulse control module is also used to directly or indirectly generate a timing start signal (start) and send it to the TDC array during the time when there is a third cycle delay relative to the measurement pulse. The TDC control module is used to send a TDC enable signal (tdc_en) to the TDC array to control the TDC units in each row of the TDC array to be turned on. The number of rows of TDC units is the same as the number of rows of SPAD pixel units in the corresponding preset row that is turned on in each subframe.

[0014] The TDC unit is used to digitally quantize the time of flight of the light pulse received by the SPAD pixel unit based on the electrical signal generated by the SPAD pixel unit.

[0015] The data processing module is used to store the flight time of the light pulses provided by each TDC unit, and also to perform data statistics based on the stored flight time of the light pulses to obtain the target direct flight time of the light pulses.

[0016] Among them, the large-area DTOF chip system satisfies the following: the node where the pulse control module outputs the measurement pulse is node O, the node where the laser drive module sends the light-driving signal tx_trig is node A, and the node where the TDC array receives the timing start signal start is node B. In terms of timing, the path delay from node O to node A is the same as the path delay from node O to node B under different temperatures and / or different voltages.

[0017] The technical solution of this invention, by setting up a large-area DTOF imaging system, utilizes the TDC control module in each subframe to control the activation of each row of TDC units in the TDC array, and utilizes the SPAD control module to control the activation of the SPAD pixel units in the SPAD pixel array corresponding to the preset row of the current subframe, thus realizing the partitioned scanning of SPAD pixel units and the time-division multiplexing function of TDC units; utilizes the pulse control module to control the generation of measurement pulses at preset periodic or non-periodic pulse intervals, thus realizing the periodic or non-periodic illumination function of the laser; and in terms of timing, the path delay from node O to node A is the same as the path delay from node O to node B under different temperatures and / or different voltages. Through the above functions, the resource consumption of the imaging system and the measurement speed of TOF are balanced, the influence of temperature and voltage changes on the measurement results of TOF values ​​is avoided, and the stability and accuracy of TOF value measurement under different temperature and voltage fluctuations are improved.

[0018] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic diagram of the structure of a DTOF imaging system provided for the present technology;

[0021] Figure 2 This is a schematic diagram of the structure of a DTOF imaging system provided in an embodiment of the present invention;

[0022] Figure 3 A timing diagram of a DTOF imaging system provided in an embodiment of the present invention;

[0023] Figure 4 A timing diagram for measuring path delay is provided in an embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram of the structure of a second DTOF imaging system provided in an embodiment of the present invention;

[0025] Figure 6 A schematic diagram of the structure of the third DTOF imaging system provided in the embodiments of the present invention.

[0026] Figure 7 This is a schematic diagram of the structure of the fourth DTOF imaging system provided in the embodiments of the present invention;

[0027] Figure 8 This is a schematic diagram of the structure of the fifth DTOF imaging system provided in the embodiments of the present invention;

[0028] Figure 9 This is a schematic diagram of a pipeline data processing function provided in an embodiment of the present invention;

[0029] Figure 10 This is a schematic diagram of a second type of pipeline data processing function provided in an embodiment of the present invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] In one embodiment, Figure 2 This is a schematic diagram of the structure of a DTOF imaging system provided in an embodiment of the present invention. Figure 3 This is a timing diagram of a DTOF imaging system provided in an embodiment of the present invention. Figure 4 This invention provides a timing diagram for measuring path delay. This embodiment is applicable to the measurement of time-of-flight (tof) values ​​in large-area DTOF imaging systems. Figures 2 to 4As shown in the figure, the system includes: a large-area array DTOF chip system 1, a laser 2, a transmitting optical system 3, and a receiving optical system 4; the large-area array DTOF chip 1 system includes a pulse control module 11, a lighting control module 12, a laser driving module 13, a SPAD pixel array 14, a SPAD control module 15, a TDC array 16, a TDC control module 17, and a data processing module 18; the SPAD pixel array 14 includes a plurality of SPAD pixel units arranged in an m*n array, and the TDC array 16 includes a plurality of TDC units arranged in an m*i array; where m, n, and i are all positive integers, and i < n; the working process of the DTOF imaging system includes multiple working frames, and each working frame includes multiple sub-frames; in each sub-frame, the pulse control module 11 is used to control the generation of multiple measurement pulses according to a preset number of pulses and a preset pulse interval, and directly or indirectly generate a laser enable signal laser_en according to each measurement pulse in sequence; the lighting control module 12 is used to directly or indirectly generate a lighting trigger signal trig_group according to the laser enable signal laser_en; the laser driving module 13 is used to emit a lighting driving signal tx_trig according to the lighting trigger signal trig_group to control the laser 2 to light up in the current sub-frame at a time with a first cycle delay relative to the measurement pulse; the transmitting optical system 3 is used to project the optical pulse emitted by the laser 2 onto the target object 5 in each sub-frame, and after being reflected by the target object 5, it is transmitted to the SPAD pixel units of the preset row corresponding to the current sub-frame through the receiving optical system 4; in each sub-frame, the pulse control module 11 is further used to generate a spad enable signal spad_pulse according to the measurement pulse; the SPAD control module 15 is used to directly or indirectly generate a SPAD enable signal spad_en according to the spad enable signal spad_pulse to control the SPAD pixel units of the preset row corresponding to the current sub-frame in the SPAD pixel array 14 to be turned on; where the SPAD pixel units of different preset rows in the SPAD pixel array 14 are turned on in different sub-frames. Taking the full-resolution output of the SPAD pixel array 14 as an example, in the same working frame, all the SPAD pixel units in the SPAD pixel array 14 will complete the turning-on process in the corresponding sub-frames; the SPAD pixel units are used to collect optical pulses and generate electrical signals; in each sub-frame, the pulse control module 11 is further used to directly or indirectly generate a timing start signal start and send it to the TDC array 16 at a time with a third cycle delay relative to the measurement pulse, and the TDC control module 17 is used to send a TDC enable signal tdc_en to the TDC array 16 to control the rows of TDC units in the TDC array 16 to be turned on; where the number of rows of the TDC units is the same as the number of rows of the SPAD pixel units of the preset row corresponding to each sub-frame.The TDC unit is used to digitally quantize the flight time of the light pulse received by the SPAD pixel unit based on the electrical signal generated by the SPAD pixel unit. The data processing module 18 is used to store the flight time of the light pulse provided by each TDC unit, and also to perform data statistics based on the stored flight time of the light pulse to obtain the target direct flight time of the light pulse. The large-area DTOF chip system satisfies the following: taking the node where the pulse control module 11 outputs the measurement pulse as node O, the node where the laser drive module 13 emits the light-driving signal tx_trig as node A, and the node where the TDC array 16 receives the timing start signal start as node B, the path delay from node O to node A is the same as the path delay from node O to node B under different temperatures and / or different voltages.

[0033] In a typical large-area DTOF chip system 1, the pulse interval between the multiple measurement pulses generated by the pulse control module 11 is constant by default. That is, the preset pulse interval between adjacent measurement pulses generated each time the light is emitted is unchanged, and the number of measurement pulses generated is also constant, i.e., multiple measurement pulses are generated according to a preset number of pulses. However, in some application scenarios, interference can easily occur when the pulse control module 11 generates measurement pulses according to the preset pulse interval. For example, under certain conditions, two large-area DTOF imaging systems are working simultaneously, namely system E and system F. The light emitted by system E is received by system F. Since both systems emit light periodically, if the preset pulse intervals of the two systems are the same, the light from system E has greater echo energy than the light emitted by system F. Therefore, each time system F receives interference light from system E, the quantized value is the same. This results in the interference light from system E being accumulated as a peak value when system F obtains the time-of-flight (tof) value by constructing a histogram or other data processing methods, leading to an incorrect measurement result for system F. Therefore, the pulse control module 11 in the large-area DTOF chip system 1 provided in this application... Figure 1 Based on the lighting control module 12, a function to generate pseudo-random sequences is added. Through the pulse control module 11, the function can be selectively switched from periodic lighting to non-periodic lighting. In other words, the preset pulse interval is no longer a fixed value, but a value that can be changed as required. Figure 3 Taking the first row of the timing diagram as an example, the pulse control module 11 controls the generation of multiple measurement pulses. The preset pulse interval of the measurement pulses is variable, meaning the interval between illuminations is variable and can be pseudo-random. When there is a scene with periodic interference light, the pulse control module 11 controls the activation of the non-periodic illumination function, such as... Figure 3The preset pulse periods in the measurement pulse timing diagram of the first row are all different, so that the quantization results of the periodic interference light are different each time. Thus, when the system obtains the time-of-flight (TOF) value by constructing a histogram or other data processing methods, it can effectively avoid the formation of false peaks, and avoid the mutual interference of multiple DTOF imaging systems, resulting in incorrect measurement results of the DTOF imaging system.

[0034] In addition, since the TDC unit consumes a large amount of hardware resources, in order to balance resources and speed, the system realizes the time-division multiplexing function of the TDC array 16 through the SPAD control module 15, also known as partition scanning. In this embodiment, the SPAD pixel array 14 includes multiple SPAD pixel units arranged in an m*n array, and due to resource limitations, the TDC array 16 is provided with multiple TDC units arranged in an m*i array (m, n, and i are all positive integers, and i < n). Usually, i = n / int, where int is a positive integer. In actual work, the first i rows of SPAD pixel units can be turned on first, and the TDC array 16 processes the electrical signals output by these i rows of SPAD pixel units. After completing the established preset number of pulses, it is recorded as the end of the first sub-frame; then the (i + 1)-th row to the 2i-th row of SPAD pixel units are turned on, and the TDC array 16 processes the electrical signals output by these i rows of SPAD pixel units. After completing the established preset number of pulses, it is recorded as the end of the second sub-frame; and so on. Through partition scanning, the time-division multiplexing of the TDC array 16 is realized, and the output processing of the electrical signals of the m*n SPAD pixel units is completed with m*i TDC units.

[0035] Therefore, in the structure of the large-area array DTOF chip system 1 provided by the present invention, the SPAD control module 15 outputs the SPAD enable signal spad_en signal to control whether different preset rows of SPAD pixel units in the SPAD pixel array 14 are turned on. Figure 3 Taking the sixth to ninth row timing diagrams as an example, during the first sub-frame, the SPAD enable signal spad_en[1:i] is turned on at a preset pulse interval. Figure 3 Taking i = 2 as an example in [reference], the clock of the SPAD enable signal spad_en[i + 1:n] is in the off state. Figure 3 Taking i + 1 = n - 1 as an example in [reference], and so on. During the corresponding sub-frame time, the SPAD enable signal spad_en of the corresponding preset row works normally with the measurement pulse, and the SPAD enable signals spad_en of other rows remain off. Thus, the time-division multiplexing function of the TDC of the large-area array DTOF chip system 1 can be realized, saving area and balancing resources and speed.

[0036] At the same time, taking Figure 3Taking the timing diagram of the SPAD enable signal spad_en in rows 6 to 9 as an example, the SPAD control module 15 can control the SPAD enable signal spad_en[1:n] not to be continuously enabled within the subframe, but to be selectively set to be enabled with a delay at each preset pulse interval, and the delay time is configurable, thereby realizing the function of selectively delaying the activation of the SPAD pixel unit. The function of delaying the activation of the SPAD pixel unit is generally used to filter photons of light pulses that return prematurely from nearby target objects 5, and the configurable delay time also provides a basis for more complex measurement schemes.

[0037] Specifically, the DTOF imaging system operates through multiple working frames, each containing multiple subframes. During each subframe imaging process, the pulse control module 11 first generates multiple measurement pulses, maintaining or changing the preset pulse interval between them, and directly or indirectly generates a laser enable signal `laser_en` based on each measurement pulse. After passing through the illumination control module 12, the laser enable signal `laser_en` directly or indirectly generates and outputs an illumination trigger signal `trig_group` based on `laser_en`. That is, the laser enable signal `laser_en` directly generates the illumination trigger signal `trig_group` through the illumination control module 12, or it works in conjunction with the illumination control module 12 to generate the illumination trigger signal `trig_group`. The generated illumination trigger signal `trig_group` is sent to the laser drive module 13, which then sends an interval-controllable illumination drive signal `tx_trig` based on the illumination trigger signal `trig_group` to control the laser 2 to emit light. In addition, since the tof value is calculated by measuring the time interval between the time when the light pulse is emitted and the time when the TDC array 15 receives the light pulse, there is a first cycle delay between the laser enable signal laser_en and the light drive signal tx_trig relative to the measurement pulse.

[0038] Simultaneously, after the pulse control module 11 generates multiple measurement pulses, it also generates a SPAD enable signal `spad_pulse` based on the measurement pulses. The SPAD control module 15 directly or indirectly generates a SPAD enable signal `spad_en` based on the `spad_pulse` and sends it to the SPAD pixel array 14 to control whether different rows of SPAD pixel units in the SPAD pixel array 14 are enabled. Since there is a second-cycle delay between the time the SPAD pixel array 14 receives the light pulse and the measurement pulse, the SPAD control module 15 can selectively delay the enabling of SPAD pixel units in different rows of the SPAD pixel array 14. That is, the SPAD enable signal `spad_en` of different preset rows of SPAD pixel units in the SPAD pixel array 14 corresponding to the current subframe is enabled with a delay following the measurement pulse, while the SPAD enable signal `spad_en` of SPAD pixel unit rows not corresponding to the current subframe remains off within the current subframe. In different subframes, there are SPAD pixel units corresponding to different preset rows. For example, if the current subframe scans the first and second rows of SPAD pixel array 14, then the preset rows are 1 and 2. At this time, the SPAD pixel units in the first and second rows are controlled to turn on after a delay of the second cycle following the measurement pulse. The SPAD pixel units in the remaining rows, that is, the SPAD pixel units from the third to the nth row, remain low-powered, i.e., in an invalid state, during the current subframe time.

[0039] Simultaneously, in each subframe, the pulse control module 12 directly or indirectly generates a timing start signal (start) during the third-cycle delay relative to the measurement pulse and sends it to the TDC array 16. The TDC control module 17 outputs a TDC enable signal (tdc_en) to the TDC array 16 to control whether each row of TDC units in the TDC array 16 is enabled, and optionally enables them in a time-division multiplexing manner. The enabling of each row of TDC units is controlled by the TDC control module 17, and the enabling of each row of TDC units is sequentially delayed. Assuming the data processing time for one row of TDC data is Tμs, then the TDC unit of the next row will be enabled after a delay of Tμs. In addition, the number of rows of TDC units in this embodiment is the same as the number of rows of SPAD pixel units in the corresponding preset rows that are opened in each subframe. For example, in the DTOF imaging system, the TDC array has 2 rows of TDC units and the SPAD pixel array 14 has 100 rows of SPAD pixel units. Then, each subframe completes the imaging of 2 rows of SPAD pixel units. There are a total of 50 subframes in a working frame of a complete image. Each subframe is processed sequentially. After the previous subframe ends, the current subframe is entered.

[0040] Next, the light pulse emitted from the illuminated area in laser 2 passes through the transmitting optical system 3 and is emitted to the target object 5. After being reflected by the target object 5, it is transmitted through the receiving optical system 4 to the SPAD pixel unit in the preset row of the SPAD pixel array 14 corresponding to the current subframe. The SPAD pixel unit collects the reflected light pulse and generates an electrical signal. At the same time, the SPAD pixel array 14 generates a timing stop signal and transmits it to each row of TDC units in the TDC array 16. The TDC unit quantizes the flight time of the light pulse received by the SPAD pixel unit based on the electrical signal generated by the SPAD pixel unit. Combined with the timing start signal input to the TDC array 16, the TDC unit can finally obtain the quantization result.

[0041] Next, after the pulse control module 11 completes the preset number of pulses, the data processing module 18 stores the flight time of the optical pulses provided by each TDC unit and performs data statistics based on the stored flight time of the optical pulses to obtain the target direct flight time of the optical pulses.

[0042] Finally, after the current subframe is completed, the next subframe begins. When all the predetermined subframes are completed, the measurement of one working frame is finished.

[0043] In addition, in practical large-area DTOF imaging systems, reference Figure 2 Let the node where the pulse control module 11 outputs the measurement pulse be node O, the node where the laser drive module 13 sends the illumination drive signal tx_trig be node A, and the node where the TDC array 16 receives the timing start signal start be node B. The illumination signal path from the pulse control module 11 to the laser drive module 13 is the OA path, and the total delay of the OA path is denoted as TX - total delay. The TDC timing start signal path from the pulse control module 11 to the TDC array 16 is the OB path, and the total delay of the OB path is denoted as TDC - total delay. Here, OA and OB are the measurement paths. Since in the actual DTOF imaging system, the path from the SPAD pixel array 14 to the TDC array 16 is the timing end signal stop, the timing end signal stop path has a relatively small delay compared to the OA and OB paths, and the timing end signal stop path delay can be equivalently added to the OA path delay, therefore, only the above measurement paths OA and OB need to be analyzed.

[0044] The different delays of the measurement paths OA and OB will affect the TDC quantization results, causing a discrepancy between the measured TOF value and the actual optical pulse flight time. For example... Figure 4As shown, clk is the clock signal of the DTOF imaging system. The illumination drive signal tx_trig, the timing start signal start, and the SPAD enable signal spad_en share a common reference signal, namely the measurement pulse ( Figure 4 (Taking k=1 and n=1 as an example). The total delay of the illumination drive signal tx_trig relative to the measurement pulse consists of two parts: period delay and path delay. The period delay is controlled by the logic circuit, and its delay is x times the clk cycle, where x is a natural number input to the logic circuit. Typically, the period delay is designed to meet system functional requirements. In this embodiment, the period delay of the illumination drive signal tx_trig relative to the measurement pulse is the first period delay, the period delay of the SPAD enable signal spad_en relative to the measurement pulse is the second period delay, and the period delay of the timing start signal start relative to the measurement pulse is the third period delay. The path delay refers to the delay during circuit transmission, mainly the transmission delay of the devices traversed during transmission; therefore, the path delay varies with temperature and voltage. The delays of the timing start signal start and the SPAD enable signal spad_en relative to the measurement pulse are similar.

[0045] According to the measurement principle of DTOF, the difference between the delay of measurement path OA and the delay of measurement path OB, i.e., the difference between TX-total delay and TDC-total delay, is part of the measurement deviation. Furthermore, since the period delay is known and always equal to x times the clk period, only the difference between TX-total delay and TDC-total delay needs to be considered as the main research object. In this embodiment, the path delay from node O to node A is the same as the path delay from node O to node B under different temperatures and / or different voltages, ensuring that the difference between TX-path delay and TDC-path delay remains constant during the measurement process. This results in a stable 16-quantization result for the final TDC array and high accuracy of the measured TOF value.

[0046] The technical solution of this invention, through the establishment of a large-area DTOF imaging system, utilizes a TDC control module in each subframe to control the activation of each row of TDC units in the TDC array, and utilizes a SPAD control module to control the activation of SPAD pixel units in the SPAD pixel array corresponding to the preset row of the current subframe, thereby realizing the partitioned scanning of SPAD pixel units and the time-division multiplexing function of TDC units. A pulse control module controls the generation of measurement pulses at preset periodic or aperiodic pulse intervals, realizing the periodic or aperiodic illumination function of the laser. Furthermore, the path delay from node O to node A is made the same as the path delay from node O to node B under different temperatures and / or different voltages. Through these functions, the resource consumption of the imaging system and the measurement speed of TOF are balanced, the influence of temperature and voltage changes on the measurement results of TOF values ​​is avoided, and the stability and accuracy of TOF value measurement under different temperature and voltage fluctuations are improved.

[0047] Figure 5 This is a schematic diagram of the structure of the second DTOF imaging system provided in an embodiment of the present invention, with reference to... Figure 3 and Figure 5 As shown, laser 2 is an addressable laser 21, and the light trigger signal trig_group is a partition trigger signal trig_group. The light control module 12 is used to directly or indirectly generate the partition trigger signal trig_group according to the laser enable signal laser_en. The laser drive module 13 is used to send the light drive signal tx_trig according to the partition trigger signal trig_group, so as to control the preset partition in the addressable laser 21 corresponding to the current subframe to be lit during the first period delay relative to the measurement pulse. The transmitting optical system 3 is used to project the light pulse emitted from the lit area of ​​the addressable laser 21 onto the target object 5 in each subframe, and after being reflected by the target object 5, it is transmitted to the SPAD pixel unit of the preset row corresponding to the current subframe through the receiving optical system 4.

[0048] Among them, the addressable laser 21 is a technology that enables individual control and addressing of each transmitter in a laser array. It allows the lasers to be lit in a specific mode or sequence, achieving precise beam control and scanning.

[0049] Specifically, due to the time-division multiplexing function of the TDC array 16, i.e., partitioned scanning, the SPAD pixel units do not work simultaneously, therefore, it is unnecessary to illuminate the total field of view corresponding to all SPAD pixel units. In this embodiment, the partitioned lighting characteristic is achieved through the lighting control module 12. The lighting control module 12 outputs a partition trigger signal `trig_group`, which, in conjunction with the working state of the SPAD pixel units, controls the addressable laser 21 to illuminate only the preset partition corresponding to the current subframe, while other subframes remain in a low-level off state, thus achieving partitioned lighting. Figure 3 Taking the second and third rows of the timing diagram as an example, during the first subframe, the SPAD pixel units in the first and second rows are working. The illumination area of ​​the addressable laser 21 only needs to cover the area corresponding to the SPAD pixel units in the first and second rows. This area is controlled by the partition trigger signal trig_group[1]. Therefore, during the first subframe, after the partition trigger signal trig_group[1] is transmitted to the laser driving module 13, the laser driving module 13 sends the illumination driving signal tx_trig according to the partition trigger signal trig_group[1], and controls the addressable laser 21 to illuminate this area. During this period, the partition trigger signal trig_group[2:k] remains at a low level, that is, in an invalid state. Similarly, during the last subframe, rows n-1 and n of the SPAD pixel units are active, and the corresponding areas are controlled by the partition trigger signal trig_group[k]. Therefore, the laser drive module 13 controls the addressable laser 21 to illuminate the area according to the partition trigger signal trig_group[k], while the partition trigger signal trig_group[1:k-1] remains low during this period. In each subframe, the transmitting optical system 3 projects the light pulse emitted from the illuminated area of ​​the addressable laser 21 onto the target object 5, and after being reflected by the target object 5, it is transmitted through the receiving optical system 4 to the SPAD pixel unit of the preset row corresponding to the current subframe, so that the light pulse is converted into an electrical signal.

[0050] It should be noted that the regions controlled by each bit of the partition trigger signal trig_group[1:k] do not need to have a strict correspondence with the regions corresponding to the SPAD pixel units. For example, in a certain subframe, if the r-th row and the (r+1)-th row of the SPAD pixel units are working, the region corresponding to the r-th row of the SPAD pixel units is controlled to be lit by the partition trigger signal trig_group[p], and the region corresponding to the (r+1)-th row of the SPAD pixel units is controlled to be lit by the partition trigger signal trig_group[q]. In this case, during the imaging process of the subframe, the partition trigger signals trig_group[p] and trig_group[q] work simultaneously. That is, the partition trigger signals trig_group[1:k] coordinate with the working state of the SPAD pixel units to control the addressable laser 21 to light up the corresponding preset partitions. This can achieve the regional lighting characteristic, thereby improving the light energy utilization rate and the system detection capability.

[0051] In another alternative embodiment, Figure 6 This is a schematic diagram of the structure of a third type of DTOF imaging system provided in an embodiment of the present invention. The large-area DTOF chip system 1 includes a digital circuit section 20 and an analog circuit section 30. A pulse control module 11, an illumination control module 12, a SPAD control module 15, a TDC control module 17, and a data processing module 18 are located in the digital circuit section 20. The SPAD pixel array 14, the TDC array 16, and the laser driving module 13 are located in the analog circuit section 30. The analog circuit section 30 also includes a delay control module 301. The input terminal of the delay control module 301 receives the measurement pulse from the pulse control module 11. The delay control module 301 includes three output terminals, which are respectively connected to the laser driving module 13, the SPAD pixel array 15, and the TDC array 16, to adjust the output according to the measurement pulse. The pulse generates a laser enable signal laser_en, which, together with the trigger control signal trig_ctrl output by the illumination control module 12, generates an illumination trigger signal trig_group, which is provided to the laser drive module 13. Based on the measured pulse, a pad enable signal pad_pulse is generated, which, together with the pad enable control signal pad_en_ctrl output by the SPAD control module 15, generates a pad enable signal pad_en, which is provided to the SPAD pixel array 14. Based on the measured pulse, a timing start signal start is generated and sent to the TDC array 16. The delay control module 301 satisfies the following: the number and type of buffers on the path from node O to node A are consistent with the number and type of buffers on the path from node O to node B.

[0052] Optionally, the delay control module 301 includes a synchronization circuit 3011, a light-emitting delay control circuit 3012, a light-emitting control AND gate 3013, a TDC delay control circuit 3014, a SPAD delay control circuit 3015, and a SPAD AND gate 3016. The pulse control module 11 is electrically connected to the synchronization circuit 3011 to provide measurement pulses to the synchronization circuit 3011. The synchronization circuit 3011 is electrically connected to the light-emitting delay control circuit 3012, the TDC delay control circuit 3014, and the SPAD delay control circuit 3015 to provide synchronous measurement pulse signals pulse_syn to the light-emitting delay control circuit 3012, the TDC delay control circuit 3014, and the SPAD delay control circuit 3015. Both the light-emitting delay control circuit 3012 and the light-emitting control module 12 are electrically connected to the light-emitting control AND gate 3013. The light-emitting delay control circuit 3012 is used to generate a laser enable signal laser_en based on the synchronous measurement pulse signal pulse_syn. The illumination control AND gate 3013 is used to generate an illumination trigger signal `trig_group` based on the laser enable signal `laser_en` and the trigger control signal `trig_ctrl`, and provides it to the laser drive module 13. The TDC delay control circuit 3014 is electrically connected to the TDC array 16 and is used to generate a timing start signal `start` based on the synchronous measurement pulse signal `pulse_syn`, and provide it to the TDC array 16. The SPAD delay control circuit 3015 and the SPAD control module 15 are both electrically connected to the SPAD AND gate 3016. The SPAD delay control circuit 3015 is used to generate a `spad_pulse` signal based on the synchronous measurement pulse signal `pulse_syn`, and the SPAD AND gate 3016 is used to generate a `spad_en` signal based on the `spad_pulse` signal and the `spad_en_ctrl` signal, and provide it to the SPAD pixel array 14.

[0053] According to the above embodiment, the difference between TX-total delay and TDC-total delay varies with temperature and voltage. In addition to the configurable periodic delay, there is also path delay in both TX-total delay and TDC-total delay. The main component of path delay is the buffer delay. A buffer is a device used to increase drive capability when the line from one point to another in the actual layout is too long. Typically, a buffer itself is equivalent to two inverters connected in series; this device itself has a delay, and this delay varies with temperature and voltage. The longer the line between two points in the actual layout, the more buffers need to be inserted. The buffers in the digital circuit section 20 are automatically inserted by software, while those in the analog circuit section 30 are manually inserted.

[0054] In the actual circuit of the DTOF chip system 1, when the traces are long, buffers must be inserted to increase the driving capability. The buffer delay is a major component of the path delay, and this delay is unavoidable. When different paths insert different numbers of buffers according to the driving capability requirements, the buffer delay will vary with temperature and voltage. Therefore, when the number and type of buffers on the illumination signal path (OA) and the TDC timing start signal path (OB) are different, the path delay will vary with temperature and voltage, ultimately causing the difference between TX-total delay and TDC-total delay to vary with temperature and voltage, thus affecting the TDC quantization result and the accuracy and stability of the TOF value.

[0055] Therefore, to ensure the accuracy and stability of the TOF value, in this embodiment, through structural adjustment, the main components of the illumination signal path (OA) and the TDC timing start signal path (OB) are moved to the analog circuit section 30, leaving only the path (O-O') in the digital circuit section 20. For example... Figure 6 As shown, Figure 6 The white box area represents the digital circuit section 20, and the gray box area represents the analog circuit section 30. In this structure, before entering the analog circuit section 30, the digital circuit section 20 follows the same path (O-O'). After entering the analog circuit section 30, due to the large optimization space of the analog circuit section 30, the number and type of buffers can be manually adjusted. Therefore, in the analog circuit section 30, by making the buffers of the illumination signal path (OA) and the TDC timing start signal path (OB) consistent, that is, the number and type of buffers on the path from node O to node A are consistent with the number and type of buffers on the path from node O to node B, so that the illumination signal path (OA) and the TDC timing start signal path (OB) change the same value with temperature and voltage fluctuations, thus making the difference between TX-total delay and TDC-total delay remain stable under temperature and voltage changes. Utilizing the large optimization space of the analog circuit section 30, the path balancing problem is handled in the analog circuit section 30, improving the accuracy and stability of the TOF value measurement under different temperature and voltage fluctuations.

[0056] Meanwhile, in the structure of this large-area DTOF chip system 1, a delay control module 301 is configured in the analog circuit section 30. The delay control module 301 includes a synchronization circuit 3011, a lighting delay control circuit 3012, a lighting control AND gate 3013, a TDC delay control circuit 3014, a SPAD delay control circuit 3015, and a SPAD AND gate 3016, and is configured with necessary logic control functions before being input to the corresponding modules. The synchronization circuit 3011, lighting delay control circuit 3012, lighting control AND gate 3013, TDC delay control circuit 3014, SPAD delay control circuit 3015, and SPAD AND gate 3016 replace some of the functions of the original SPAD control module 15, TDC control module 17, pulse control module 11, and lighting control module 12, simplifying the original structure. It only needs to output a quasi-static signal for line control instead of a pulse signal to achieve complete functionality without increasing additional resource consumption.

[0057] Specifically, based on the workflow of the above embodiments, during each subframe imaging process, the pulse control module 11 of the large-area DTOF chip system 1 outputs a measurement pulse, i.e., a pluse signal. The measurement pulse is transmitted to the synchronization circuit 3011. The synchronization circuit 3011 generates a synchronization measurement pulse signal pulse_syn based on the measurement pulse and transmits it to the illumination delay control circuit 3012. The illumination delay control circuit 3012 indirectly generates a laser enable signal laser_en and controls the preset pulse interval of the light pulse to remain unchanged or change. The laser enable signal laser_en, together with the trigger control signal trig_ctrl output by the illumination control module 12, is indirectly generated by the illumination control AND gate 3013 to generate an illumination trigger signal trig_group. The generated illumination trigger signal trig_group is provided to the laser drive module 13. The laser drive module 13 sends an illumination drive signal tx_trig with a preset pulse interval controllable to drive the addressable laser 21 to emit light.

[0058] Simultaneously, the pulse control module 11 outputs a measurement pulse, which, after passing through the synchronization circuit 3011, generates a synchronous measurement pulse signal pulse_syn. The synchronous measurement pulse signal pulse_syn, after passing through the TDC delay control circuit 3014, generates a timing start signal start and is sent to the TDC array 16.

[0059] Simultaneously, the pulse control module outputs a measurement pulse, which, after passing through the synchronization circuit 3011, generates a synchronous measurement pulse signal pulse_syn. The SPAD delay control circuit 3015 indirectly generates a SPAD enable signal spad_pulse based on the synchronous measurement pulse signal pulse_syn. This signal, together with the SPAD enable control spad_en_ctrl output by the SPAD control module 15, passes through the SPAD AND gate 3016 to indirectly generate a SPAD enable signal spad_en, thereby controlling whether SPAD pixel units in different rows of the SPAD pixel array 14 are turned on, and selectively delaying their on.

[0060] The technical solution of this invention has a simple structure and does not require the addition of a complex correction module. Based on the principle of delay generation, it optimizes the analog path to keep the delay difference between the OA and OB paths stable, avoiding the influence of temperature and voltage changes on the measurement results and improving the accuracy and stability of the measured toF value under different temperature and voltage fluctuations. On the other hand, the analog circuit part is optimized with high precision and accuracy, and the TDC array is implemented in the analog circuit, which can further optimize area and power consumption.

[0061] In another alternative embodiment, Figure 7 This is a schematic diagram of the structure of the fourth DTOF imaging system provided in the embodiments of the present invention, with reference to... Figure 5 and Figure 7 As shown, the large-area DTOF chip system 1 includes a digital circuit section 20 and an analog circuit section 30; the pulse control module 11, the illumination control module 12, the SPAD control module 15, the TDC array 16, the TDC control module 17, and the data processing module 18 are located in the digital circuit section 20, and the SPAD pixel array 14 and the laser driving module 13 are located in the analog circuit section 30; the DTOF imaging system also includes an internal optical path 6, and the analog circuit section 30 is also provided with a reference SPAD pixel unit 302; the internal optical path 6 is used to transmit the light pulse emitted by the laser 2 to the reference SPAD pixel unit 302 within the DTOF imaging system; the reference SPAD pixel unit 302 is used to generate a timing start signal start according to the time of receiving the light pulse and send it to the TDC array 16.

[0062] Optionally, the pulse control module 11 is electrically connected to the illumination control module 12, the SPAD control module 15, and the TDC array 16, respectively. The pulse control module 11 is used to generate a laser enable signal laser_en and a SPAD enable signal spad_pulse according to the measurement pulse, so as to provide them to the illumination control module 12 and the SPAD control module 15, respectively.

[0063] Specifically, based on the above embodiments, refer to Figure 7 , Figure 7 The white box area represents the digital circuit section 20, and the gray box area represents the analog circuit section 30. In this embodiment, a separate reference SPAD pixel unit 302 is set up, and the timing path is changed to generate a timing start signal "start" using the reference SPAD pixel unit 302. The addressable laser 21 transmits the echo signal of the light pulse emission time to the reference SPAD pixel unit 302 through the internal optical path 6. After receiving the echo signal, the reference SPAD pixel unit 302 measures its time value as the timing start signal "start". This is equivalent to implementing the light emission signal path (OA path) and the TDC timing start signal path (OB path) through the same path. Therefore, the change in path delay has no impact on the TDC quantization result, thereby improving the accuracy and stability of the measured TOF value.

[0064] Based on the above embodiments, in this embodiment, during each subframe imaging process, the pulse control module 11 of the large-area DTOF chip system 1 generates a laser enable signal laser_en according to the measurement pulse, and controls the preset pulse interval of the measurement pulse to remain constant or change. The laser enable signal laser_en directly outputs a lighting trigger signal trig_group through the lighting control module 12. The lighting trigger signal trig_group passes through the laser drive module 13 to emit a lighting drive signal tx_trig with a controllable preset pulse interval, driving the addressable laser 21 to emit light. At the same time, the reference SPAD pixel unit 302 generates a timing start signal start according to the time of the echo signal of the received light pulse, and sends it to the TDC array 16.

[0065] Meanwhile, the pulse control module 11 generates a SPAD enable signal spad_pluse based on the measurement pulse and provides it to the SPAD control module 15. The SPAD control module 15 directly generates a SPAD enable signal spad_en based on the SPAD enable signal spad_pluse, and controls whether the SPAD pixel units in different preset rows in the SPAD pixel array 14 are enabled, and optionally enables them with a delay.

[0066] The technical solution of this invention implements the same path for the illumination signal path and the TDC timing start signal path, so that changes in path delay have no impact on the measurement results, thereby improving the accuracy and stability of the measured TOF value under different temperature and voltage fluctuations.

[0067] In another alternative embodiment, Figure 8 This is a schematic diagram of the structure of the fifth DTOF imaging system provided in the embodiments of the present invention, with reference to... Figure 8As shown, the data processing module 18 is also used to correct the target flight time of the optical pulse according to the path delay difference under different pre-calibrated temperatures and / or different voltages; wherein, the path delay difference is the difference between the path delay from node O to node A and the path delay from node O to node B in terms of timing.

[0068] Based on the above embodiments, refer to Figure 8 As shown, Figure 8 The white box area represents the digital circuit section 20, and the gray box area represents the analog circuit section 30. The lighting trigger signal `trig_group`, the timing start signal `start`, and the pad enable signal `spad_en` are all logically controlled in the digital circuit section 20 before being input to the corresponding modules. During the implementation of the back-end of the digital circuit section 20, placement and routing are performed by EDA software. The number and type of inserted buffers are automatically determined by the EDA software based primarily on drive capability and static timing requirements.

[0069] Since the difference between TX (total delay) and TDC (total delay) is fixed at a given temperature and voltage, this embodiment can pre-calibrate the path delay difference under different temperatures and / or voltages, and then correct the TDC quantization result by real-time monitoring of temperature and voltage. For example, through calibration experiments, when measuring a target object located at a meter at a temperature of x℃ and a voltage of yV, the result given by the large-area DTOF chip system 1 is always a+z meters; thus, the path delay difference at a temperature of x℃ and a voltage of yV is z meters. A series of path delay differences corresponding to different temperatures and voltages are calibrated using the same method. Subsequently, the results given by the large-area DTOF chip system 1 are all subtracted from the aforementioned path delay difference corresponding to the current temperature and voltage to complete the correction of the target flight time of the light pulse, thereby correcting the TDC quantization result. It should also be noted that this embodiment is more suitable for scenarios where the system's operating environment is stable.

[0070] Based on the above embodiments, in this embodiment, during each subframe imaging process, the pulse control module 11 of the large-area DTOF chip system 1 directly controls the measurement pulse to generate a laser enable signal laser_en, and controls the preset pulse interval of the measurement pulse to remain constant or be variable. The laser enable signal laser_en is directly output as a lighting trigger signal trig_group by the lighting control module 12. The lighting trigger signal trig_group is then passed through the laser drive module 13 to issue a lighting drive signal tx_trig with a controllable preset pulse interval, driving the addressable laser 21 to emit light. At the same time, the pulse control module 11 controls the measurement pulse to directly generate a timing start signal start, which is sent to the TDC array 16.

[0071] Meanwhile, the pulse control module 11 controls the measurement pulse to generate a SPAD enable signal spad_pluse and provides it to the SPAD control module 15. The SPAD control module 15 then directly generates a SPAD enable signal spad_en to control whether the SPAD pixel units in different preset rows of the SPAD pixel array 14 are enabled, and optionally delays the enable.

[0072] The technical solution of this invention has a simple structure and does not require consideration of delay issues during design. It ultimately corrects the target flight time of the optical pulse by using a pre-calibrated path delay difference, eliminating the influence of path delay on the measurement results and improving the accuracy and stability of the TOF value measurement. Furthermore, the logic control parts of this embodiment are all implemented in the digital circuit section, resulting in better portability when chip manufacturing processes change.

[0073] In another alternative embodiment, reference continues... Figure 6 As shown, the data processing module 18 includes a histogram module array 181 and a data processing module group 182; the histogram module array 181 is used to store the flight time of the light pulses provided by each TDC unit and draw histograms; the data processing module group 182 is used to perform data statistics on the histograms to obtain the target direct flight time of the light pulses.

[0074] Specifically, after the pulse control module 11 completes the preset number of pulses, the histogram module array 181 in the data processing module 18 stores the time-of-flight data quantized by the TDC array 16 during the period from light pulse transmission to reception. The data processing module group 182 in the data processing module 18 statistically analyzes the data in the histogram and processes the statistical data to obtain the target direct flight time, i.e., the tof value. Based on the valid target direct flight time tof value, the distance to the target object 5 can be obtained, thus obtaining the measurement result. The histogram module array 181 includes histogram modules, and the histogram modules correspond one-to-one with the TDC units in the TDC array 16, with the same number of corresponding modules. When the data processing module group 182 performs statistical processing on the histogram data, it processes the data of each histogram sequentially. After processing all the histogram data in the first row, it processes the histogram data in the next row. Finally, the target direct flight time is obtained.

[0075] In another alternative embodiment, Figure 9 This is a schematic diagram of a pipeline data processing function provided in an embodiment of the present invention, with reference to... Figure 3 and Figure 9 As shown, in each subframe, the TDC control module 17 is also used to send a TDC enable signal tdc_en to the TDC array 16 to control each row of TDC units in the TDC array 16 to be turned on sequentially according to a preset delay time ΔT'.

[0076] Here, the data processing time of one row of TDC units is T1, and ΔT'=T1; in two adjacent subframes, the end time t1 of the data processing of the last row of TDC units in the previous subframe and the end time t2 of the data generation of the first row of TDC units in the next subframe satisfy: t1≤t2.

[0077] Typically, in a large-area DTOF chip system 1, a subframe includes TDC data generation and data processing, and the rate of TDC data generation is greater than the data processing rate of subsequent data processing modules. To reduce the total time of each subframe and increase the frame rate of the entire large-area DTOF chip system 1, this embodiment implements pipelined data processing functionality through the TDC control module 17. Specifically, the TDC control module 15 outputs a TDC enable signal tdc_en to control each row of TDC units in the TDC array 16, causing the TDC units to sequentially activate according to a preset delay time ΔT'. Figure 3 Taking the timing diagram of the fourth and fifth rows as an example, the TDC enable signal tdc_en[1] controls whether the TDC unit in the first row is turned on, and the TDC enable signal tdc_en[i] controls whether the TDC unit in the i-th row is turned on. Furthermore, the TDC units in each row can be turned on sequentially according to a preset delay time ΔT'. (Reference) Figure 9 The first four lines are timing diagrams of the TDC unit in the prior art, and the last four lines are timing diagrams of the TDC unit based on pipeline data processing in this embodiment. In the prior art, such as Figure 9 As shown in the first four lines, multiple TDC units generate data simultaneously, and the time-division processing of this data results in a longer total time for each subframe and a lower system frame rate. In the solution provided by this invention, as... Figure 9 As shown in the last four lines, by controlling the time-sharing activation of multiple TDC units, the activation times of multiple TDC units are staggered, so that the time for TDC units to generate data is closely connected with the time for data processing. In this way, the TDC units of the previous row start and end first, and the TDC units of the next row start and end later, and so on. This ensures that each subframe processes data normally, while reducing the total time of each subframe, reducing the time of pipeline data processing, improving the system frame rate, and improving the system resource utilization.

[0078] In addition, the data processing time of a row of TDC units is T1. When the time when TDC units generate data in two adjacent subframes is close to the time when data is processed, the start time of TDC units generating data in the next subframe coincides with the end time of data processing in the previous subframe. That is to say, the preset delay time between TDC units generating data in two adjacent subframes is the time of one data processing, i.e., ΔT'=T1, and the end time t1 of the last row of data processing in the previous subframe is less than the end time t2 of the first row of TDC units generating data in the next subframe.

[0079] Optional, continue to refer to Figure 9 As shown, with the duration of data generation by a row of TDC units as T2, when T2≥(i-1)×T1, the delay time ΔT” of the opening time of the same row of TDC units in two adjacent subframes satisfies: ΔT”=T1+T2.

[0080] Specifically, when the time for TDC unit to generate data is closely connected to the time for data processing, if the TDC unit includes 4 rows, i = 4, and T2 ≥ (i-1) × T1, indicating that the duration of data generation by one row of TDC units in the current subframe is greater than the processing time of 3 rows of data in the previous subframe, it means that the data generation of the first row of TDC units in the second subframe has not yet ended, and the data processing of the last row of the previous subframe has ended. Therefore, in two adjacent subframes, the end time of the last row of data processing in the previous subframe and the start time of the first row of output processing in the next subframe will not coincide. This ensures that data processing in each subframe can proceed normally, reducing data processing time. In this case, the delay time ΔT” of the start time of the same row of TDC units in two adjacent subframes is the sum of the time for TDC unit data generation and the data processing time in the previous subframe, i.e., ΔT” = T1 + T2.

[0081] Optional, Figure 10 This is a schematic diagram of the second type of pipeline data processing function provided in an embodiment of the present invention, with reference to... Figure 10 As shown, with the duration of data generation by a row of TDC units as T2, when T2≤(i-1)×T1, in two adjacent subframes, the end time of data generation by the first row of TDC units in the later subframe is the same as the end time of data processing by the last row of TDC units in the previous subframe, and the delay time ΔT” of the opening time of the same row of TDC units satisfies: ΔT”=i×T1.

[0082] Specifically, if the TDC unit includes 4 rows, i = 4, and T2 ≤ (i-1) × T1, it means that when the duration of data generation by one row of TDC units in the current subframe is less than the processing time of 3 rows of data in the previous subframe, it indicates that the end time of data processing of the last row of data in the previous subframe is greater than the end time of data generation by the first row of TDC units in the next subframe. To ensure that data processing in each subframe does not overlap, the start time of data generation by TDC units in the next subframe needs to be delayed. This ensures that the end time of data generation by the first row of TDC units in the next subframe is consistent with the end time of data processing of the last row of TDC units in the previous subframe. This guarantees normal data processing in each subframe while reducing the total time of each subframe, reducing the pipeline data processing time, increasing the system frame rate, and improving system resource utilization. In this case, the delay time ΔT” for the start time of the same row of TDC units can be expressed as ΔT” = i × T1, that is, the delay time is the sum of the processing times of all rows of data in the previous subframe.

[0083] It should be noted that the lasers in the above embodiments are all addressable lasers 21. For non-addressable lasers, such as ordinary lasers, ... Figure 2 As shown, the first light-driving signal tx_trig[1] is selected from the light-driving signal tx_trig emitted by the laser driving module 13, so that the light-driving signal tx_trig[1] is sent to the non-addressable ordinary laser, and the ordinary laser is controlled to only light up in the area of ​​the first light-driving signal; or, the laser driving module 13 is designed to generate only one light-driving signal tx_trig, so that the ordinary laser is controlled to only light up in the light-driving area. That is, the non-addressable laser is not lighted in different areas, but the laser driving module 13 is controlled in different areas to realize the light pulse output of the non-addressable laser. The specific settings can be made according to the actual situation, and will not be elaborated here.

[0084] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0085] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A DTOF imaging system, characterized in that, This includes a large-area DTOF chip system, a laser, a transmitting optical system, and a receiving optical system; The large-area DTOF chip system includes a pulse control module, a light control module, a laser drive module, a SPAD pixel array, a SPAD control module, a TDC array, a TDC control module, and a data processing module. The SPAD pixel array includes multiple SPAD pixel units arranged in an m*n array, and the TDC array includes multiple TDC units arranged in an m*i array; where m, n, and i are all positive integers, and i <n; The working process of the DTOF imaging system includes multiple working frames, and each working frame includes multiple subframes. In each subframe, the pulse control module is used to control the generation of multiple measurement pulses according to a preset number of pulses and a preset pulse interval, and to generate a laser enable signal laser_en directly or indirectly according to each measurement pulse; the illumination control module is used to generate an illumination trigger signal trig_group directly or indirectly according to the laser enable signal laser_en; the laser drive module is used to send an illumination drive signal tx_trig according to the illumination trigger signal trig_group, so as to control the laser to light up in the current subframe during a time with a first period delay relative to the measurement pulse; The transmitting optical system is used to project the light pulse emitted by the laser onto the target object in each subframe, and after being reflected by the target object, it is transmitted through the receiving optical system to the SPAD pixel unit in the preset row corresponding to the current subframe. In each subframe, the pulse control module is further configured to generate a SPAD enable signal `spad_pulse` based on the measurement pulse; the SPAD control module is configured to directly or indirectly generate a SPAD enable signal `spad_en` based on the `spad_pulse`, so as to control the SPAD pixel units in the SPAD pixel array corresponding to the current subframe to be enabled during a second period delay relative to the measurement pulse; wherein, the SPAD pixel units in different preset rows of the SPAD pixel array are enabled in different subframes; the SPAD pixel units are used to acquire the light pulse and generate electrical signals. In each subframe, the pulse control module is further configured to directly or indirectly generate a timing start signal (start) and send it to the TDC array during a third-cycle delay relative to the measurement pulse. The TDC control module is configured to send a TDC enable signal (tdc_en) to the TDC array to control the TDC units in each row of the TDC array to be turned on. The number of rows of the TDC units is the same as the number of rows of the SPAD pixel units in the corresponding preset row that is turned on in each subframe. The TDC unit is used to digitally quantize the flight time of the light pulse when the SPAD pixel unit receives the light pulse, based on the electrical signal generated by the SPAD pixel unit. The data processing module is used to store the flight time of the light pulses provided by each TDC unit, and is also used to perform data statistics based on the stored flight time of the light pulses to obtain the target direct flight time of the light pulses. The large-area DTOF chip system satisfies the following: the node where the pulse control module outputs the measurement pulse is node O, the node where the laser drive module sends the light-driving signal tx_trig is node A, and the node where the TDC array receives the timing start signal start is node B. In terms of timing, the path delay from node O to node A is the same as the path delay from node O to node B under different temperatures and / or different voltages.

2. The DTOF imaging system according to claim 1, characterized in that, The large-area DTOF chip system includes digital circuitry and analog circuitry. The pulse control module, the lighting control module, the SPAD control module, the TDC control module, and the data processing module are located in the digital circuit section, while the SPAD pixel array, the TDC array, and the laser drive module are located in the analog circuit section. The analog circuit section also includes a delay control module, the input of which receives the measurement pulse from the pulse control module; The delay control module includes three output terminals, which are respectively connected to the laser driving module, the SPAD pixel array, and the TDC array. Based on the measurement pulse, it generates a laser enable signal `laser_en`, which, in conjunction with the trigger control signal `trig_ctrl` output by the illumination control module, generates an illumination trigger signal `trig_group`, which is provided to the laser driving module. Based on the measurement pulse, it generates a pad enable signal `spad_pulse`, which, in conjunction with the pad enable control signal `spad_en_ctrl` output by the SPAD control module, generates a pad enable signal `spad_en`, which is provided to the SPAD pixel array. Based on the measurement pulse, it generates a timing start signal `start`, which is sent to the TDC array. The delay control module satisfies the following: the number and type of buffers on the path from node O to node A are consistent with the number and type of buffers on the path from node O to node B.

3. The DTOF imaging system according to claim 2, characterized in that, The delay control module includes a synchronization circuit, a lighting delay control circuit, a lighting control AND gate, a TDC delay control circuit, a SPAD delay control circuit, and a SPAD AND gate; The pulse control module is electrically connected to the synchronization circuit to provide the measurement pulse to the synchronization circuit; The synchronization circuit is electrically connected to the lighting delay control circuit, the TDC delay control circuit, and the SPAD delay control circuit, respectively, to provide a synchronization measurement pulse signal pulse_syn to the lighting delay control circuit, the TDC delay control circuit, and the SPAD delay control circuit; Both the illumination delay control circuit and the illumination control module are electrically connected to the illumination control AND gate. The illumination delay control circuit is used to generate the laser enable signal laser_en based on the synchronous measurement pulse signal pulse_syn. The illumination control AND gate is used to generate the illumination trigger signal trig_group based on the laser enable signal laser_en and the trigger control signal trig_ctrl, and provide it to the laser drive module. The TDC delay control circuit is electrically connected to the TDC array and is used to generate the timing start signal start based on the synchronous measurement pulse signal pulse_syn and provide it to the TDC array. Both the SPAD delay control circuit and the SPAD control module are electrically connected to the SPAD AND gate. The SPAD delay control circuit is used to generate the SPAD enable signal spad_pulse based on the synchronous measurement pulse signal pulse_syn. The SPAD AND gate is used to generate the SPAD enable signal spad_en based on the SPAD enable signal spad_pulse and the SPAD enable control signal spad_en_ctrl, and provide it to the SPAD pixel array.

4. The DTOF imaging system according to claim 1, characterized in that, The large-area DTOF chip system includes digital circuitry and analog circuitry. The pulse control module, the lighting control module, the SPAD control module, the TDC array, the TDC control module, and the data processing module are located in the digital circuit section, while the SPAD pixel array and the laser driving module are located in the analog circuit section. The DTOF imaging system also includes an internal optical path, and the analog circuit section is further provided with a reference SPAD pixel unit. The internal optical path is used to transmit the light pulse emitted by the laser to the reference SPAD pixel unit within the DTOF imaging system; The reference SPAD pixel unit is used to generate the timing start signal "start" based on the time of receiving the light pulse and send it to the TDC array.

5. The DTOF imaging system according to claim 4, characterized in that, The pulse control module is electrically connected to the lighting control module, the SPAD control module, and the TDC array, respectively. The pulse control module is used to generate the laser enable signal laser_en and the SPAD enable signal spad_pulse according to the measurement pulse, so as to provide them to the illumination control module and the SPAD control module respectively.

6. The DTOF imaging system according to claim 2 or 4, characterized in that, The data processing module includes a histogram module array and a data processing module group; The histogram module array is used to store the flight time of the light pulses provided by each TDC unit and to draw histograms; The data processing module group is used to perform data statistics on the histogram to obtain the target direct flight time of the light pulse.

7. The DTOF imaging system according to claim 1, characterized in that, In each subframe, the TDC control module is also used to send a TDC enable signal tdc_en to the TDC array to control the TDC units in each row of the TDC array to be turned on sequentially according to a preset delay time ΔT'. Here, the data processing time of one row of TDC units is T1, and ΔT'=T1; in two adjacent subframes, the end time t1 of the data processing of the last row of TDC units in the previous subframe and the end time t2 of the data generation of the first row of TDC units in the next subframe satisfy: t1≤t2.

8. The DTOF imaging system according to claim 7, characterized in that, Let T2 be the duration of data generation by a row of TDC units. When T2≥(i-1)×T1, the delay time ΔT” of the opening time of the same row of TDC units in two adjacent subframes satisfies: ΔT”=T1+T2.

9. The DTOF imaging system according to claim 7, characterized in that, Let T2 be the duration of data generation by a row of TDC units. When T2≤(i-1)×T1, in two adjacent subframes, the end time of data generation by the first row of TDC units in the later subframe is the same as the end time of data processing by the last row of TDC units in the previous subframe. The delay time ΔT” of the opening time of the same row of TDC units satisfies: ΔT”=i×T1.

10. The DTOF imaging system according to claim 1, characterized in that, The laser is an addressable laser, and the light-emitting trigger signal trig_group is a partition trigger signal trig_group; The lighting control module is used to directly or indirectly generate the partition trigger signal trig_group according to the laser enable signal laser_en; the laser drive module is used to send a lighting drive signal tx_trig according to the partition trigger signal trig_group, so as to control the preset partition in the addressable laser corresponding to the current subframe to be lit during a first period delay relative to the measurement pulse. The transmitting optical system is used to project the light pulse emitted from the illuminated area of ​​the addressable laser onto the target object in each subframe, and after being reflected by the target object, it is transmitted through the receiving optical system to the SPAD pixel unit in the preset row corresponding to the current subframe.

11. The DTOF imaging system according to claim 1, characterized in that, The data processing module is also used to correct the target flight time of the light pulse based on the path delay difference under different pre-calibrated temperatures and / or voltages. The path delay difference is the difference in timing between the path delay from node O to node A and the path delay from node O to node B.

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