Distance measuring optical sensor device and distance measuring method

Abstract

The application relates to a ranging optical sensor device and a ranging method. The device comprises: a photoelectric conversion module, which comprises a pixel array, the pixel array comprising N rows and M columns of SPAD units, the SPAD units being used for receiving distance data reflected by a target object in a current time period, a first selector being used for sequentially selecting distance data of K+1th to K+Xth rows; wherein K is a natural number, and X is a positive integer; X-stage time-to-digital conversion modules being used for respectively receiving distance data of the K+1th to K+Xth rows; X-stage histogram statistical modules being used for performing histogram statistics on distance data of the K+1th to K+Xth rows to obtain accumulated data of the K+1th to K+Xth rows; a second selector being used for selecting the accumulated data in time to obtain sample data of one of X rows of accumulated data; and a digital signal processing module being used for performing digital signal processing on the sample data to obtain target distance data.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical ranging, in particular to a ranging optical sensor device and a ranging method. BACKGROUND

[0002] At present, for unmanned aerial vehicles, sweeping robots, mobile phones and self-driving cars, the ranging optical sensor with intelligent ranging and obstacle avoidance function is generally built-in. The ranging optical sensor is generally a module, which generally includes a light emitting device and a light receiving and ranging device. The light receiving and ranging chip includes a photoelectric conversion module, a time data conversion module (TDC), a histogram statistics module, a digital signal processing module (DSP) and a data transmission module.

[0003] In actual application, the light emitting chip emits photons, the photons are reflected back at the target object, and the photoelectric conversion module generates a corresponding signal at the moment of receiving the photons. The time-to-digital conversion module calculates the time of flight of the photons according to the signal, and performs histogram statistics and digital signal processing on the time of flight data of different photons. Finally, the calculated distance data is sent to the outside of the ranging optical sensor through the data transmission module.

[0004] Patent CN114114300B provides a scattered point redistribution ranging device and a laser detection system, as shown in Figure 1 The invention adopts the same number of TDCs and identifiers, the same number of arbiters and DSP units, which avoids strict optical calibration. However, multiple DSPs work at the same time, resulting in high power consumption and large chip design area of the scheme.

[0005] Therefore, the related technology has the following problems: first, when the resolution of the receiving device is large (the number of pixels of the photoelectric conversion device is large), the chip design occupies a large area and consumes a large amount of power; second, in each working cycle, there is a time window, and all photoelectric conversion devices stop receiving in the time window. Discontinuous reception will miss some important information. SUMMARY

[0006] Therefore, the present application provides a ranging optical sensor device and a ranging method. For multiple rows of pixel arrays, only X rows of pixels are activated each time, and the X rows of pixel data are processed. The method of interleaving the working time of different rows of photoelectric conversion modules instead of the discontinuous receiving method is used to increase the effective ranging time window length of the ranging optical sensor. The method of initializing the memory of the histogram module corresponding to different rows of data at different times instead of the existing method of simultaneously initializing the memory corresponding to all data rows is used to reduce power consumption. The method of serially calling the digital processing module and the data transmission module instead of the existing parallel processing structure is used to reduce the area and power consumption.

[0007] To achieve the above object, the application mainly adopts the following technical scheme: the application provides a ranging optical sensor device, which comprises: a photoelectric conversion module, the photoelectric conversion module comprising: a pixel array, the pixel array comprising N rows and M columns of SPAD (Single Photon Avalanche Diode) units, the SPAD units being used for receiving flight distance data of photons reflected by a target object in a current time period, wherein N and M are positive integers; a first selector connected with each row of the pixel array, the first selector being used for sequentially selecting distance data of the K+1th row to the K+Xth row; wherein K is a natural number and X is a positive integer; X-level time-to-digital conversion modules, one end of each of the time-to-digital conversion modules being connected with the first selector respectively, and being used for receiving the distance data of the K+1th row to the K+Xth row respectively; X-level histogram statistics modules, one end of each of the histogram statistics modules being connected with the other end of each of the time-to-digital conversion modules respectively, and being used for performing histogram statistics on the distance data of the K+1th row to the K+Xth row to obtain accumulated data of the K+1th row to the K+Xth row; a second selector connected with the other end of each of the histogram statistics modules, the second selector being used for selecting the accumulated data in time to obtain one row of X rows of accumulated data as sample data; and a digital signal processing module connected with the second selector, the digital signal processing module being used for performing digital signal processing on the sample data to obtain target distance data.

[0008] In some embodiments, the device further comprises: a transmission module and a host computer, the transmission module being connected with the photoelectric conversion module and being used for transmitting the target distance data to the host computer.

[0009] In some embodiments, each of the histogram statistics modules comprises: a histogram accumulator, one end of the histogram accumulator being connected with the time-to-digital conversion module and being used for performing histogram statistics on the distance data of the K+1th row to the K+Xth row; a SRAM (Static Random Access Memory), one end of the SRAM being connected with the other end of the histogram accumulator and being used for writing the X rows of accumulated data; the other end of the SRAM being connected with the digital signal processing module through the second selector and being used for reading out the accumulated data from the SRAM by the digital signal processing module; and a controller, the controller being connected with the SRAM and being used for controlling initialization of the SRAM and writing and reading of the accumulated data.

[0010] The application further provides a ranging method using the optical sensor device, the method comprising: a SPAD array receiving photon flight distance data reflected by a target object in a current time period; a first selector selecting distance data of K+1th row to K+Xth row and sending the distance data to corresponding each time-to-digital conversion module and histogram statistics module; X-level histogram statistics modules respectively performing histogram statistics on the distance data of K+1th row to K+Xth row to obtain accumulated data of K+1th row to K+Xth row; a second selector selecting one row of the accumulated data as sample data in time and sending the sample data to a digital signal processing module; and the digital signal processing module sequentially performing digital signal processing on each sample data according to a first preset time to obtain a plurality of target distance data corresponding to each sample data.

[0011] In some embodiments, the method further comprises: a transmission module transmitting the plurality of target distance data obtained by the digital signal processing module to an upper computer.

[0012] In some embodiments, each histogram statistics module comprises a histogram accumulator, an SRAM and a controller, and the histogram statistics module respectively performs histogram statistics on the distance data of K+1th row to K+Xth row to obtain accumulated data of K+1th row to K+Xth row, which comprises: the controller controls the SRAM to initialize; after the SRAM completes initialization, the controller controls the histogram accumulator to perform histogram accumulation on the received distance data of K+1th row to K+Xth row to obtain the accumulated data of K+1th row to K+Xth row.

[0013] In some embodiments, the method further comprises: the controller writes the obtained accumulated data into the SRAM and controls the SRAM to read out the accumulated data.

[0014] In some embodiments, the method further comprises: an i-level controller in the X-level histogram statistics module controls an i-level SRAM to initialize according to a second preset time; after the i-level SRAM completes initialization, an i+1-level controller controls an i+1-level SRAM to initialize according to the second preset time, wherein i is a positive integer less than or equal to X.

[0015] The application provides a ranging optical sensor device and a ranging method, wherein X rows of data are obtained from a plurality of rows of SPAD arrays each time, the initialization time of SRAM of a histogram statistics module corresponding to the X rows of data is staggered, and the X rows of data are sent to a DSP for processing in time, so that the problem of excessive power consumption caused by simultaneous initialization of SRAM can be reduced, and the X rows of data are processed by a set of DSP modules to reduce area and power consumption. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 a schematic diagram of a principle of a point scattering redistribution ranging device in the related art;

[0017] Figure 2 a schematic diagram of a ranging optical sensor device provided by an embodiment of the present application;

[0018] Figure 3 a schematic diagram of an internal structure of a histogram statistics module in an embodiment of the present application;

[0019] Figure 4 a schematic diagram of a ranging method provided by an embodiment of the present application;

[0020] Figure 5 a timing diagram of a photoelectric conversion module in an embodiment of the present application in a frame time. DETAILED DESCRIPTION

[0021] In order to more clearly understand the above objectives, technical solutions and advantages of the present application, specific embodiments will be described in detail below with reference to the drawings. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict, and the following specific embodiments are only used to explain the present application, and are not intended to limit the present application.

[0022] In the following description, many specific details are set forth in order to fully understand the present application. The described embodiments are merely a part of the embodiments of the present application, and are not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application.

[0024] Embodiment 1

[0025] An embodiment of the present application provides a ranging optical sensor device, Figure 2 a schematic diagram of a ranging optical sensor device provided by an embodiment of the present application, see Figure 2The ranging optical sensor device comprises a photoelectric conversion module 100, which comprises a pixel array 101 comprising N rows and M columns of SPAD cells 111 for receiving photon flight distance data reflected by a target object within a current time period, wherein N and M are positive integers; each SPAD cell 111 responds to an incident single photon and outputs a signal indicating the corresponding arrival time of the received photon at each SPAD cell, and the acquisition of a weak light signal and the calculation of a time of flight are realized by using a time-correlated single photon counting method (TCSPC), so as to obtain distance data reflected by the target object within the current time period, and each SPAD cell 111 corresponds to obtain one distance data.

[0026] A first selector 102 connected to each row of the pixel array 101 is used to sequentially select distance data of the K+1th row to the K+Xth row; wherein K is a natural number, X is a positive integer, and K+X≤N. An X-level time-to-digital conversion module (TDC) 103, one end of each level of the time-to-digital conversion module is connected with the first selector respectively, and is used to receive distance data of the K+1th row to the K+Xth row.

[0027] An X-level histogram statistics module 104, one end of each level of the histogram statistics module is connected with the other end of each level of the time-to-digital conversion module respectively, and is used to perform histogram statistics on distance data of the K+1th row to the K+Xth row (each row has M data) to obtain accumulated data of the K+1th row to the K+Xth row; here, the number of the histogram statistics module 104 is the same as that of the TDC, each level of the TDC sends the corresponding distance data obtained by it to the corresponding histogram statistics module, for example, the 1st level of the TDC sends the 1st row of distance data to the 1st level of the histogram statistics module, and the Xth level of the TDC sends the Xth row of distance data to the Xth level of the histogram statistics module. After each level of the histogram statistics module 104 receives the corresponding distance data, it performs histogram statistics on the distance data to obtain accumulated data corresponding to each row of distance data.

[0028] A second selector 105 connected to the other end of each level of the histogram statistics module 104 is used to select the accumulated data in time to obtain one row of X rows of accumulated data as sample data; a digital signal processing module (DSP) 106 connected with the second selector 105 is used to perform digital signal processing on the sample data to obtain target distance data, wherein the target distance data is the actual distance between the ranging optical sensor device and the target object.

[0029] Figure 3An internal structure diagram of the histogram statistics module in the embodiment of the present application is shown in Figure 3 As shown, the histogram statistics module 104 includes a histogram accumulator 114 connected to the time-to-digital conversion module at one end, for histogram statistics of the distance data of the K+1th row to the K+Xth row; an SRAM 124 connected to the other end of the histogram accumulator 114 at one end, for writing the accumulated data of the X rows; the other end of the SRAM 124 is connected to the digital signal processing module through a second selector 105, for the digital signal processing module to read out the accumulated data from the SRAM 124; and a controller 134 connected to the SRAM 124, for controlling initialization of the SRAM 124 and writing and reading of the accumulated data. Here, after each histogram statistics module 104 receives corresponding distance data, the histogram accumulator 114 performs histogram accumulation on the distance data to obtain accumulated data corresponding to the distance data, and the controller 134 controls writing of the accumulated data into the SRAM 124, and simultaneously controls reading out of the accumulated data stored in the SRAM 124 and sending to the digital signal processing module 106 for digital signal processing.

[0030] In the embodiment of the present application, the ranging optical sensor device further includes a transmission module and a host computer, the transmission module is connected to the photoelectric conversion module, for transmitting the target distance data to the host computer.

[0031] The ranging optical sensor device provided in the embodiment of the present application is used for N rows and M columns of pixel arrays, X rows of pixels are activated each time, and the X rows of pixel data are processed, the different row photoelectric conversion module working time interleaving method is used to replace the existing discontinuous receiving method to increase the effective ranging time window length of the ranging optical sensor, the histogram statistics module corresponding to different row data is used to replace the existing simultaneous initialization of the memory corresponding to all data rows to reduce power consumption, the serial calling of the digital processing module and the data transmission module is used to replace the existing parallel processing structure to reduce area and power consumption, and the ranging time and efficiency of the ranging optical sensor device are increased.

[0032] Embodiment 2

[0033] The embodiment of the present application provides a ranging method using the above optical sensor device, Figure 4 A flowchart of the ranging method provided in the present application is shown in Figure 4 The method includes:

[0034] Step S10: The pixel array receives the flight distance data of the photons reflected by the target object in the current time period.

[0035] Referring to Figure 2 The pixel array includes N rows and M columns of SPAD units, each of which is capable of receiving the flight distance data of the photons reflected by the target object in the current time period, including the flight time of the reflected light from the photon emission to the target object, reflection to the SPAD.

[0036] Step S20: The first selector selects the distance data of the K+1th row to the K+Xth row and sends them to the corresponding time data conversion module and histogram statistics module respectively.

[0037] Here, the first selector 102 selects the distance data of X rows from the K+1th row to the K+Xth row from the N rows of pixel arrays in turn and sends them to the X-level time-to-digital conversion module 103, that is, for the pixel array including N rows of SPAD units, only X rows of them are activated each time, for example, N is 12, K is 0, and X is 4, at this time, the first selector 102 selects the distance data obtained by the SPAD units of each of the first row to the fourth row from the 12 rows of pixel arrays and sends them to the four-level time data conversion module (TDC), each level of TDC corresponds to accept the distance data of the K+1th row to the K+Xth row, for example, the first-level TDC accepts the first row distance data, the second-level TDC receives the second row distance data, and the fourth-level TDC receives the fourth row distance data, and the TDC converts the time signals in the distance data of the four rows into digital signals.

[0038] Step S30: The X-level histogram statistics modules respectively perform histogram statistics on the distance data of the K+1th row to the K+Xth row to obtain the accumulated data of the K+1th row to the K+Xth row.

[0039] Here, the number of histogram statistics modules 104 is the same as the number of TDCs, and each level of histogram statistics module 104 respectively performs histogram statistics on the corresponding distance data, that is, the first-level histogram statistics module statistics the first-level distance data.

[0040] Referring to Figure 3 In the embodiments of the present application, each of the histogram statistics modules 104 includes a histogram accumulator 114, an SRAM 124, and a controller 134, and correspondingly, step S30 includes:

[0041] Step S31: The controller controls the SARM to initialize.

[0042] Step S32: After the SRAM is initialized, the controller controls the histogram accumulator to perform histogram accumulation on the distance data from row K+1 to row K+X received, so as to obtain the accumulated data from row K+1 to row K+X.

[0043] Step S33: The controller writes the obtained accumulated data into the SRAM and controls the SRAM to read out the accumulated data.

[0044] In this embodiment, the photoelectric conversion module 100 includes an X-level histogram statistics module 104. Each histogram statistics module 104 contains a controller 134, a histogram accumulator 114, and an SRAM 124. Therefore, the photoelectric conversion module 100 includes an X-level controller, X histogram accumulators, and X SRAMs. In the X-level histogram statistics module, the i-th level controller controls the i-th level SRAM to be initialized according to a second preset time. After the i-th level SRAM is initialized, the (i+1)-th level controller controls the (i+1)-th level SRAM to be initialized according to the second preset time, where i is a positive integer ≤ X.

[0045] Step S40: The second selector selects one row of the accumulated data from the X rows as sample data and sends it to the digital signal processing module.

[0046] Step S50: The digital signal processing module performs digital signal processing on each sample data sequentially according to a first preset time to obtain multiple target distance data corresponding to each sample data.

[0047] Here, the first preset time is a fixed setting, such as 1μs. The second selector 105 selects one row of the accumulated data from the X rows as sample data and sends it to the digital signal processing module (DSP) 106. The DSP performs digital signal processing on it according to the first preset time to obtain the corresponding target distance data. Through the time-division selection of the second selector 105, the processing time of the sample data by the DSP is staggered. That is, the DSP processes the sample data of the first row first, and then starts processing the sample data of the second row after the processing is completed. In this way, the DSP is always working effectively, avoiding the problem of idle time period and signal repetition and omission in time period.

[0048] Figure 5 This is a timing diagram of the photoelectric conversion module operating within one frame in an embodiment of this application. See [link / reference]. Figure 5The first-level controller in the X-level histogram statistics module controls the first-level SRAM to initialize according to a second preset time, for example, the second preset time is 1 microsecond, when the first-level SRAM is initializing, the SRAMs of other levels are in an idle state, when the first-level SRAM completes the initialization, the second-level controller controls the second-level SRAM to initialize according to the second preset time, and so on, the X-level controller controls the X-level SRAM to initialize according to the second preset time, and after the first-level, the second-level,..., the X-level complete the SRAM initialization, the subsequent histogram accumulation processes are respectively performed.

[0049] Subsequently, the DSP processes the sample data according to a first preset time, for example, the first-level DSP processes the sample data in the first row within 1 microsecond, after the sample data in the first row is processed, the second-level DSP starts to process the sample data in the second row, until the sample data in the Xth row is processed by the Xth-level DSP.

[0050] The above process is repeated until all the distance data corresponding to the sample data in each row is processed. In a frame of time, except for the idle time at the beginning and the end, distance data is accumulated in the histogram. That is, except for the idle time, the optical sensor device is receiving photons and performing effective ranging work.

[0051] In the embodiment of the present application, the ranging method further comprises: step S60: the transmission module transmits the plurality of target distance data obtained by the digital signal processing module to an upper computer.

[0052] By the ranging method of the embodiment of the present application, the SRAM initialization time of the histogram statistics module corresponding to X rows of data is staggered, which can reduce the problem of excessive power consumption caused by simultaneous initialization of the SRAM, and the X rows of accumulated data from the histogram statistics module are processed by the DSP in an interleaved manner, the X rows of distance data can share a set of circuits for processing to reduce the area and power consumption, the effective histogram integration time is increased in a frame of time, and the ranging efficiency of the ranging optical sensor device is improved.

[0053] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any person skilled in the art can make various changes, modifications, replacements and variations to these embodiments without departing from the principles and purposes of the present application, the scope of the present application is defined by the claims and their equivalents.

Claims

1. A ranging optical sensor device, characterized in that, The device includes: a photoelectric conversion module, the photoelectric conversion module comprising: A pixel array comprising N rows and M columns of SPAD units, wherein the SPAD units are used to receive distance data reflected by the target object within the current time period, wherein N and M are positive integers; A first selector connected to each row of the pixel array, the first selector being used to sequentially select distance data from row K+1 to row K+X; where K is a natural number and X is a positive integer; X-level time-to-digital conversion modules, one end of each level of the time-to-digital conversion module is connected to the first selector, and is used to receive the distance data from the (K+1)th row to the (K+X)th row respectively; The X-level histogram statistics module is connected to the time-to-digital conversion module of the corresponding level. It is used to perform histogram statistics on the distance data from row K+1 to row K+X to obtain the cumulative data from row K+1 to row K+X. A second selector is connected to the other end of the histogram statistics module at each level. The second selector is used to perform time-division selection on the accumulated data to obtain one row of the X rows of accumulated data as sample data. A digital signal processing module connected to the second selector, the digital signal processing module being used to perform digital signal processing on the sample data to obtain target distance data; Each level of histogram statistics module includes: A histogram accumulator, one end of which is connected to the X-level time-to-digital conversion module, is used to perform histogram statistics on the distance data from row K+1 to row K+X. SRAM, one end of which is connected to the other end of the histogram accumulator, is used to write the accumulated data of the X rows; The other end of the SRAM is connected to the digital signal processing module via a second selector, which is used by the digital signal processing module to read the accumulated data from the SRAM. A controller, connected to the SRAM, is used to control the initialization of the SRAM and the writing and reading of the accumulated data.

2. The apparatus according to claim 1, characterized in that, The device also includes: a transmission module and a host computer. The transmission module is connected to the photoelectric conversion module and is used to transmit the target distance data to the host computer.

3. A ranging method using the optical sensor device as described in claim 1, characterized in that, The method includes: The pixel array receives distance data reflected by the target object within the current time period; The first selector selects the distance data from row K+1 to row K+X and sends it to the corresponding time-based digital conversion module and histogram statistics module respectively. The histogram statistics module of level X performs histogram statistics on the distance data from row K+1 to row K+X to obtain the cumulative data from row K+1 to row K+X. The second selector selects one row of the accumulated data from the X rows as sample data and sends it to the digital signal processing module in a time-division manner. The digital signal processing module performs digital signal processing on each sample data sequentially according to a first preset time to obtain multiple target distance data corresponding to each sample data. Each of the histogram statistics modules includes: a histogram accumulator, an SRAM, and a controller. Correspondingly, each histogram statistics module performs histogram statistics on the distance data from row K+1 to row K+X to obtain the accumulated data from row K+1 to row K+X, including: The controller controls the SARM to initialize; After the SRAM is initialized, the controller controls the histogram accumulator to perform histogram accumulation on the distance data from row K+1 to row K+X received, so as to obtain the accumulated data from row K+1 to row K+X.

4. The method according to claim 3, characterized in that, The method further includes: The transmission module transmits the multiple target distance data obtained by the digital signal processing module to the host computer.

5. The method according to claim 3, characterized in that, The method further includes: The controller writes the accumulated data into the SRAM and controls the SRAM to read out the accumulated data.

6. The method according to claim 5, characterized in that, The method further includes: In the X-level histogram statistics module, the i-level controller controls the i-level SRAM to initialize according to the second preset time. After the i-th level SRAM is initialized, the i+1-th level controller controls the i+1-th level SRAM to be initialized according to the second preset time, where i is a positive integer ≤ X.

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