Error calibration method and time-of-flight sensor

Abstract

The invention provides an error calibration method and a flight time sensor. The error calibration method comprises the following steps: controlling a light source to generate emitted light to irradiate a test object based on a modulation signal; controlling a plurality of demodulation signals of a plurality of pixel regions based on different delay phases, and sampling reflected light returned from the test object for multiple times to obtain multiple groups of measurement distance data and multiple groups of actual error data; determining the swing error of the flight time sensor according to the measured distance value and the actual measurement error; wherein the actual measurement error is the measurement error after the delay phase and / or the spatial distance after the moving of the sampling test object each time are / is corrected. According to the invention, the actual measurement error comprises a delay phase and / or a measurement error caused by the spatial distance after each sampling test object moves, so that the swing error calibration accuracy of the time-of-flight sensor can be ensured.

Description

Technical Field

[0001] The present application relates to the field of image technology, and in particular to an error calibration method and a time-of-flight sensor. Background Art

[0002] At present, with the increasing market interest in 3D vision and recognition technology, three-dimensional imaging technology continues to develop. Among them, the time-of-flight sensor (TOF) emits a short pulse of light and then measures the time required for the emitted light to return, thereby detecting the distance to the object and forming a three-dimensional image. In the prior art, the time-of-flight sensor has a swing error during the measurement process. The swing error refers to an error caused by an odd harmonic that changes periodically with the measured distance. The swing error seriously affects the measurement of the time-of-flight sensor. Therefore, it is necessary to calibrate the swing error of the time-of-flight sensor to compensate for the measurement distance of the time-of-flight sensor. At present, how to improve the accuracy of the calibration of the swing error of the time-of-flight sensor has become the direction of efforts of those skilled in the art. Summary of the invention

[0003] The present application provides an error calibration method and a time-of-flight sensor to solve the above technical problems.

[0004] In a first aspect, the present application provides an error calibration method, which is applied to a time-of-flight sensor, wherein the time-of-flight sensor has multiple pixel areas, and the error calibration method includes: controlling a light source to generate emitted light based on a modulation signal to illuminate a test object; controlling multiple pixel areas to perform multiple sampling of reflected light returned from the test object based on multiple demodulation signals with different delay phases to obtain multiple groups of measured distance data and multiple groups of actual error data, wherein each group of measured distance data includes multiple measured distance values ​​corresponding to the multiple pixel areas one by one, and each group of actual error data includes multiple actual measurement errors corresponding to the multiple pixel areas one by one; determining the swing error of the time-of-flight sensor based on the measured distance value of each group of measured distance data and the actual measurement error of each group of actual error data; wherein the actual measurement error is a measurement error after correction for the delay phase and / or the spatial distance after the test object moves for each sampling.

[0005] In some embodiments, the delayed phase of the Nth demodulated signal corresponding to the Nth sampling measurement and the Mth demodulated signal corresponding to the Mth sampling measurement of any pixel area are not equal to each other; or, the spatial distance of any pixel area relative to the test object at the Nth sampling measurement and the spatial distance relative to the test object at the N+1th sampling measurement are not equal to each other; wherein N and M are integers greater than or equal to 1, and N and M are not equal.

[0006] In some embodiments, the delay phase of each demodulated signal includes a local delay phase and a global delay phase relative to the modulation signal; in each sampling process, the global delay phase between each demodulated signal is equal, and the local delay phase between each demodulated signal is not equal.

[0007] In some embodiments, during multiple sampling processes, the position of the test object remains unchanged; the global delay phases of the Nth demodulated signal corresponding to the Nth sampling measurement of any pixel area and the N+1th demodulated signal corresponding to the N+1th sampling measurement differ by a first preset time length; and the local delay phases of the Nth demodulated signal corresponding to the Nth sampling measurement of any pixel area and the N+1th demodulated signal corresponding to the N+1th sampling measurement are equal.

[0008] In some embodiments, the actual measurement error is the measurement error after correction of the local delay phase.

[0009] In some embodiments, the steps of controlling multiple pixel areas to perform multiple sampling of reflected light returned from a test object based on multiple demodulation signals with different delay phases to obtain multiple sets of measured distance data and multiple sets of actual error data include: determining the measured distance value corresponding to each pixel area according to the phase difference between the emitted light and the reflected light sampled by each pixel area during each sampling process; determining the actual measurement error corresponding to each pixel area according to the global delay phase of the demodulation signal corresponding to each pixel area during each sampling process, the actual spatial distance of each pixel area relative to the measured object, and the measured distance value corresponding to each pixel area.

[0010] In some embodiments, the step of determining the actual measurement error corresponding to each pixel area according to the global delay phase of the demodulated signal corresponding to each pixel area in each sampling process, the actual spatial distance of each pixel area relative to the measured object, and the measured distance value corresponding to each pixel area includes: determining the ideal measurement error corresponding to each pixel area according to the global delay phase of the demodulated signal corresponding to each pixel area in each sampling process, the actual spatial distance of each pixel area relative to the measured object, and the measured distance value corresponding to each pixel area; determining the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area according to the ideal measurement error corresponding to the same pixel area in multiple sampling processes; compensating for the ideal measurement error corresponding to each pixel area according to the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area to obtain the actual measurement error corresponding to each pixel area.

[0011] In some embodiments, during multiple sampling processes, the test object positions are different; and the delayed phase of the Nth demodulated signal corresponding to the Nth sampling measurement and the N+1th demodulated signal corresponding to the N+1th sampling measurement of any pixel area is equal.

[0012] In some embodiments, the steps of controlling multiple pixel areas to perform multiple sampling of reflected light returned from the test object based on multiple demodulation signals with different delay phases to obtain multiple sets of measured distance data and multiple sets of actual error data include: determining the measured distance value corresponding to each pixel area according to the phase difference between the emitted light and the reflected light sampled by each pixel area during each sampling process; determining the actual measurement error corresponding to each pixel area according to the actual spatial distance of each pixel area relative to the measured object during the delay phase during each sampling process, and the measured distance value corresponding to each pixel area.

[0013] In some embodiments, the step of determining the actual measurement error corresponding to each pixel area according to the actual spatial distance of each pixel area relative to the measured object at the delay phase and the measured distance value corresponding to each pixel area includes: determining the ideal measurement error corresponding to each pixel area according to the actual spatial distance of each pixel area relative to the measured object at the delay phase and the measured distance value corresponding to each pixel area; determining the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area according to the ideal measurement error corresponding to the same pixel area in multiple sampling processes; compensating for the ideal measurement error corresponding to each pixel area according to the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area to obtain the actual measurement error corresponding to each pixel area.

[0014] In a second aspect, the present application provides a time-of-flight sensor, comprising: a light source, the light source is used to generate an emitted light according to a modulated signal; a plurality of pixel areas, the plurality of pixel areas are used to sample the reflected light returned from the irradiated object to obtain a measured distance value; wherein the time-of-flight sensor is used to calibrate the measured distance value according to the swing error obtained by the method described in the first aspect.

[0015] In some embodiments, the time-of-flight sensor further includes a delay module configured to generate a plurality of demodulated signals.

[0016] The present application uses multiple demodulation signals with different delay phases for multiple pixel areas. In each sampling process, a group of multiple measured distance values ​​corresponding to multiple pixel areas can be obtained, and a group of multiple actual measurement errors corresponding to multiple pixel areas can be obtained. Finally, after multiple measurements, multiple groups of measured distance data and multiple groups of actual error data can be obtained, so as to determine the swing error of the flight time sensor based on the multiple groups of measured distance values ​​and multiple groups of actual measurement errors. At the same time, since the actual measurement error is the measurement error corrected for the delay phase and / or the spatial distance after each sampling test object moves, that is, the actual measurement error includes the measurement error caused by the delay phase and / or the spatial distance after each sampling test object moves, it is conducive to ensuring the accuracy of the swing error calibration of the flight time sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the 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 work.

[0018] Figure 1 is a schematic diagram of a time-of-flight sensor in the related art;

[0019] Figure 2 It is a schematic diagram of emitted light and reflected light in the related art;

[0020] Figure 3 is a structural schematic diagram of a time-of-flight sensor provided in an embodiment of the present application;

[0021] Figure 4 It is a flow chart of the error calibration method provided in the embodiment of the present application;

[0022] Figure 5 It is a waveform diagram of a modulation signal and a demodulation signal provided in an embodiment of the present application;

[0023] Figure 6 is a schematic diagram of a time-of-flight sensor measurement process provided in an embodiment of the present application;

[0024] Figure 7 is a schematic diagram of a swing error curve of a time-of-flight sensor provided in an embodiment of the present application;

[0025] Figure 8 It is a schematic diagram of a modulated signal and a demodulated signal during the first sampling provided in an embodiment of the present application;

[0026] Fig. 9 It is a schematic diagram of a modulated signal and a demodulated signal during the second sampling provided in an embodiment of the present application;

[0027] Fig.10 It is a schematic diagram of a modulation signal and a demodulation signal provided in an embodiment of the present application;

[0028] Fig.11 It is a schematic diagram of a modulated signal and a demodulated signal during the first sampling provided in an embodiment of the present application;

[0029] Fig.12 It is a schematic diagram of a modulated signal and a demodulated signal during the second sampling provided in an embodiment of the present application;

[0030] Fig.13 It is a schematic diagram of a flow chart for determining multiple sets of measured distance data and multiple sets of actual error data provided in an embodiment of the present application;

[0031] Fig.14 It is a schematic diagram of a flow chart for determining an actual measurement error provided in an embodiment of the present application;

[0032] Fig.15 It is a schematic diagram of an ideal measurement error curve fitting provided in an embodiment of the present application;

[0033] Fig.16 is the spatial distance corresponding to the actual local delay phase of each pixel area provided in the embodiment of the present application;

[0034] Fig.17 It is another flow chart of determining multiple sets of measured distance data and multiple sets of actual error data provided in an embodiment of the present application;

[0035] Fig.18 It is a schematic diagram of a flow chart for determining an actual measurement error provided in an embodiment of the present application;

[0036] Among them, there are a light source 100, a pixel array 200, a control module 300, a delay module 400, an emission light TX, a reflection light RX, and a test object TEST. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0038] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0039] Moreover, the terms "comprises," "comprising," or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0040] In the description of the embodiments of the present application, words such as "example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "example" or "for example" in the embodiments of the present application is not to be interpreted as being more preferred or having more advantages than another embodiment or design. The use of words such as "example" or "for example" is intended to present relative concepts in a clear manner.

[0041] In addition, the "plurality" in the embodiments of the present application refers to two or more than two. In view of this, in the embodiments of the present application, "plurality" can also be understood as "at least two". "At least one" can be understood as one or more, for example, one, two or more. For example, including at least one means including one, two or more, and there is no limit on which ones are included. For example, including at least one of A, B and C, then A, B, C, A and B, A and C, B and C, or A, B and C can be included.

[0042] It should be noted that, in the embodiments of the present application, "and / or" describes the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / ", unless otherwise specified, generally indicates that the associated objects before and after are in an "or" relationship.

[0043] Currently, time-of-flight sensors detect the distance to an object and form a three-dimensional image by emitting a short pulse of light and then measuring the time it takes for the emitted light to return. Figure 1 , Figure 1 A schematic diagram of a time-of-flight sensor in the related art is shown. The time-of-flight sensor includes a control module, a light source and a pixel array. During the measurement process, the control module first controls the light source to output a transmitted light TX to the test object through a modulation signal MS. After the transmitted light TX is reflected by the test object, the control module controls the pixel array to measure the reflected light RX through a demodulation signal DS, and finally detects the distance to the object and forms a three-dimensional image.

[0044] More specifically, see Figure 2 , Figure 2A schematic diagram of the emission light TX and the reflected light RX in the related art is shown, wherein the horizontal axis is time and the vertical axis is light intensity. The light intensity of the emission light TX and the reflected light RX changes periodically, so the pixel array can collect the light intensity of the reflected light RX at 90°, 180°, 270° and 360° phases for each cycle of the emission light TX, and the phase difference φ between the emission light TX and the reflected light RX can be determined according to the following formula:

[0045]

[0046] Among them, A1 is the light intensity of the reflected light RX at the 90° phase of the emitted light TX, A2 is the light intensity of the reflected light RX at the 180° phase of the emitted light TX, A3 is the light intensity of the reflected light RX at the 270° phase of the emitted light TX, and A4 is the light intensity of the reflected light RX at the 360° phase of the emitted light TX.

[0047] According to the speed of light propagation, the distance d between the test object and the time-of-flight sensor can be calculated as follows:

[0048]

[0049] Wherein, c is the speed of light, and f is the emission frequency of the emitted light TX.

[0050] It can be seen that by determining the phase difference φ between the emitted light TX and the reflected light RX, the purpose of detecting the distance to the object and forming a three-dimensional image can be achieved. However, the time-of-flight sensor has a swing error during the measurement process. The swing error refers to an error caused by an odd harmonic that changes periodically with the measured distance. The swing error seriously affects the measurement of the time-of-flight sensor. Therefore, the time-of-flight sensor needs to be calibrated for the swing error to compensate for the measurement distance of the time-of-flight sensor.

[0051] In the related art, a solution for calibrating the swing error of a time-of-flight sensor is provided, which moves a test object to a known position, measures the distance between the time-of-flight sensor and the test object, and obtains the swing error of the time-of-flight sensor at the measured distance by comparing the measured distance with the actual spatial distance. However, the actual spatial distance corresponding to the test object moving to the known position is not accurate, which will cause the calibrated swing error to include the movement error of the test object, thereby causing the problem of reduced accuracy in the calibration of the swing error of the time-of-flight sensor.

[0052] To this end, the embodiments of the present application provide an error calibration method and a time-of-flight sensor, which are described in detail below.

[0053] Before introducing the error calibration method of the present application, the time-of-flight sensor of the present application is first introduced. First, refer to Figure 3 , Figure 3 A structural schematic diagram of a time-of-flight sensor in an embodiment of the present application is shown, wherein the time-of-flight sensor includes a control module 300, a light source 100, a pixel array 200 and a delay module 400. The time-of-flight sensor can use the swing error obtained by any of the error calibration methods described below to calibrate the measured distance value.

[0054] Specifically, the light source 100 may emit an emission light TX with periodic changes (e.g., light intensity), for example, the light intensity of the emission light TX has a waveform of a pulse wave, a sine wave, a cosine wave, etc. Exemplarily, the light source 100 may include, but is not limited to, an organic light emitting diode, an inorganic light emitting diode, a quantum dot light emitting diode, a laser diode, etc.

[0055] The pixel array 200 is used to receive the reflected light RX reflected by the object, so as to output an electrical signal related to the reflected light RX (e.g., light intensity). Exemplarily, the pixel array 200 may include depth pixels or color pixels, so as to realize distance measurement or provide a black and white image through the depth pixels, or provide a three-dimensional color image with color pixel information and depth information through the color pixels.

[0056] The control module 300 may send control signals for controlling the light source 100, the pixel array 200 and the delay module 400, and / or receive output signals such as control signals from the light source 100, the pixel array 200 and the delay module 400. For example, the control module 300 may provide a modulation signal MS to control the light source 100 to generate the emission light TX; for another example, the control module 300 may provide a clock signal to output a plurality of demodulation signals DS1-DS8 for controlling the pixel array 200 through the delay module 400; for another example, the control module 300 may receive an electrical signal about the reflected light RX output by the pixel array 200, so as to determine the phase difference between the reflected light RX and the emission light TX according to the electrical signal of the reflected light RX. Exemplarily, the control module 300 may include a control logic circuit, a phase-locked loop circuit, a timing control circuit, an analog-to-digital conversion circuit, a communication interface circuit, and the like.

[0057] The delay module 400 can receive a clock signal from the control module 300 and generate a demodulation signal for controlling the pixel array 200 to perform sampling. In the embodiment of the present application, the pixel array 200 is divided into a plurality of pixel regions PR1 to PR8, and the control module 300 generates a plurality of demodulation signals DS1 to DS8 through the delay module 400, so that each pixel region can perform reflected light RX sampling through a demodulation signal. Exemplarily, the delay module 400 may include, but is not limited to, a circuit composed of one or more of a logic gate, a trigger, an inverter, and an RC delay circuit.

[0058] It is worth noting that the above Figure 3 The contents about the time-of-flight sensor are only for illustration and should not be understood as limiting the time-of-flight sensor of the present application. Figure 3 Each column of pixels is divided into a pixel area, but it is not limited to this. For example, every two columns of pixels or every row of pixels can be divided into a pixel area. For another example, the delay module 400 can also be set outside the time-of-flight sensor, and the control module 300 generates a plurality of demodulation signals DS1~DS8 for controlling a plurality of pixel areas PR1~PR8 through the external delay module 400. For another example, the time-of-flight sensor can also only have a pixel array 200 and a light source 100.

[0059] Continue reading Figure 4 , Figure 4 A schematic flow chart of an error calibration method in an embodiment of the present application is shown. The method can perform error calibration on the time-of-flight sensor described in any of the above embodiments. The error calibration method includes:

[0060] Step S401 : controlling the light source 100 to generate emission light TX based on the modulation signal MS to illuminate the test object TEST.

[0061] Specifically, the control module 300 can send a modulation signal MS, which is a control signal for controlling the light source 100 to generate the emission light TX. Generally, the modulation signal MS and the emission light TX change periodically. For example, the modulation signal MS can be a clock signal, and the emission light TX is a sine wave signal with periodic changes in light intensity. It can be understood that the waveforms of the modulation signal MS and the emission light TX are not limited thereto. For example, the modulation signal MS can also be a sine wave signal, a cosine wave signal, a triangular wave signal, etc. For another example, the emission light TX can also be a sine wave signal, a cosine wave signal, a triangular wave signal or a square wave signal, etc.

[0062] The test object TEST is used to receive the irradiation of the emission light TX to generate the reflected light RX returned to the pixel array 200. In some embodiments of the present application, the test object TEST can be movable during the error calibration process to change the spatial distance between the test object TEST and the time-of-flight sensor, thereby measuring the measurement error of the time-of-flight sensor at different spatial distances. In some embodiments of the present application, during the error calibration process, the test object TEST can also be fixed differently, and the spatial distance between the test object TEST and the time-of-flight sensor can be changed by moving the moving position of the time-of-flight sensor or changing the phase of the demodulated signal, thereby measuring the measurement error of the time-of-flight sensor at different spatial distances.

[0063] In some embodiments of the present application, the side of the test object TEST that receives the emitted light TX is a flat surface, for example, the test object TEST may be a flat plate, so as to facilitate the measurement of the known distance between the test object TEST and each pixel area of ​​the pixel array 200. It can be understood that the test object TEST may also be an object with a complex surface, for example, the test object TEST may be a cylinder.

[0064] Step S402 , controlling multiple pixel areas to perform multiple sampling of the reflected light RX returned from the test object TEST based on multiple demodulation signals with different delay phases, so as to obtain multiple groups of measured distance data and multiple groups of actual error data.

[0065] The control module 300 can send out a plurality of demodulation signals DS1 to DS8 through the delay module 400. Each demodulation signal is a control signal that controls each pixel area of ​​the pixel array 200 to receive the reflected light RX (for example, the light intensity of the reflected light RX at the phases of 90°, 180°, 270°, and 360° of the modulation signal MS) and generate an electrical signal. The delay phases of the plurality of demodulation signals are different. The delay phase refers to the phase difference of the demodulation signal relative to the modulation signal MS. For example, see Figure 5 , Figure 5 A waveform diagram of the modulation signal MS and the demodulation signal in the embodiment of the present application is shown, wherein the period of the modulation signal MS is T, the phase difference between the demodulation signal DS1 corresponding to the pixel area PR1 and the demodulation signal DS2 corresponding to the pixel area PR2 is 8 / T, the phase difference between the demodulation signal DS2 corresponding to the pixel area PR2 and the demodulation signal DS3 corresponding to the pixel area PR3 is 8 / T, the phase difference between the demodulation signal DS3 corresponding to the pixel area PR3 and the demodulation signal DS4 corresponding to the pixel area PR4 is 8 / T, and so on, so that the delayed phase of the demodulation signal corresponding to each pixel area PR1 is different.

[0066] It should be noted that, since the delayed phase of the demodulated signal corresponding to each pixel area PR1 is different from each other, even if the test object TEST is a flat plate, the measured distance value obtained by each pixel area is different. For example, taking the phase difference between the demodulated signal DS1 corresponding to the pixel area PR1 and the demodulated signal DS2 corresponding to the pixel area PR2 as 8 / T, if the pixel area PR1 measures the phase difference φ1 between the emitted light TX and the reflected light RX, and the pixel area PR2 measures the phase difference φ2 between the emitted light TX and the reflected light RX, then:

[0067] Φ2=φ1+T / 8

[0068] Therefore, the measured distance value obtained by the pixel area PR1 and the measured distance value obtained by the pixel area PR2 satisfy:

[0069] d2=d1+T / 8*c

[0070] Wherein, d1 is the measured distance value obtained by the pixel area PR1, and d2 is the measured distance value obtained by the pixel area PR2.

[0071] The same is true for other pixel areas. It can be seen that since the delayed phase of the demodulated signal corresponding to each pixel area PR1 is different, the measured distance value measured in each pixel area is different, so as to measure the measurement error of the time-of-flight sensor at different spatial distances, and finally fit the swing error of the time-of-flight sensor.

[0072] The multiple pixel regions can perform multiple sampling of the reflected light RX returned from the test object TEST based on multiple demodulation signals with different delay phases, so as to obtain multiple groups of measured distance data and multiple groups of actual error data, wherein each group of measured distance data includes multiple measured distance values ​​corresponding to the multiple pixel regions one by one, and each group of actual error data includes multiple actual measured errors corresponding to the multiple pixel regions one by one. For example, after the multiple pixel regions perform the first sampling of the reflected light RX, the first group of measured distance data will be obtained; after the multiple pixel regions perform the second sampling of the reflected light RX, the second group of measured distance data will be obtained, and so on. After the multiple pixel regions perform N samplings, N groups of measured distance data can be obtained.

[0073] In some embodiments of the present application, the spatial distance of any pixel region relative to the test object TEST during the Nth sampling measurement is different from the spatial distance relative to the test object TEST during the N+1th sampling measurement; wherein N is an integer greater than or equal to 1, that is, each set of measured distance data represents the measurement data of multiple pixel regions of the test object TEST at different spatial positions. For example, see Figure 6 , Figure 6A schematic diagram of the measurement process of the time-of-flight sensor in an embodiment of the present application is shown. After the reflected light RX is sampled for the first time by multiple pixel areas and a first set of measured distance data is obtained, the position of the test object TEST is changed, and then the reflected light RX is sampled for a second time by multiple pixel areas and a second set of measured distance data is obtained; after the second set of measured distance data is obtained, the position of the test object TEST is changed again, and then the reflected light RX is sampled for a third time by multiple pixel areas and a third set of measured distance data is obtained, and so on, so that multiple sets of measurement data can be obtained.

[0074] It should be noted that since each set of measured distance data represents the measurement data of multiple pixel areas of the test object TEST at different spatial positions, combined with an embodiment in which the delay phase of the demodulation signal corresponding to each pixel area PR1 is different from each other, a large number of distance measurement values ​​and actual measurement errors at different spatial distances can be obtained, thereby making the swing error calibration of the time-of-flight sensor more accurate.

[0075] For example, Figure 5 Taking the phase difference between the demodulated signals corresponding to adjacent pixel areas as 8 / T as an example, the distance measurement values ​​obtained by four samplings are shown in the following table:

[0076] Pixel area sampling times First sampling Second sampling The third sampling The fourth sampling PR1 D11 D12 D13 D14 PR2 D11+T / 8*c D12+T / 8*c D13+T / 8*c D14+T / 8*c PR3 D11+2T / 8*c D12+2T / 8*c D13+2T / 8*c D14+2T / 8*c PR4 D11+3T / 8*c D12+3T / 8*c D13+3T / 8*c D14+3T / 8*c PR5 D11+4T / 8*c D12+4T / 8*c D13+4T / 8*c D14+4T / 8*c PR6 D11+5T / 8*c D12+5T / 8*c D13+5T / 8*c D14+5T / 8*c PR7 D11+6T / 8*c D12+6T / 8*c D13+6T / 8*c D14+6T / 8*c PR8 D11+7T / 8*c D12+7T / 8*c D13+7T / 8*c D14+7T / 8*c

[0077] Among them, D11 is the spatial distance between the pixel area PR1 and the test object TEST at the first sampling, D12 is the spatial distance between the pixel area PR1 and the test object TEST at the second sampling, D13 is the spatial distance between the pixel area PR1 and the test object TEST at the third sampling, and D14 is the spatial distance between the pixel area PR1 and the test object TEST at the fourth sampling.

[0078] It can be seen that due to the differences in D11, D12, D13, and D14, a large number of distance measurement values ​​and actual measurement errors at different spatial distances can be obtained, thereby making the swing error calibration of the time-of-flight sensor more accurate.

[0079] Step S403 : determining the swing error of the time-of-flight sensor according to the measured distance value of each set of measured distance data and the actual measured error of each set of actual error data.

[0080] After obtaining multiple sets of measured distance values ​​and multiple sets of actual measurement errors, the swing error of the time of flight sensor can be determined. In some embodiments of the present application, the swing error of the time of flight sensor can be obtained by fitting according to multiple measured distance values ​​and multiple actual measurement errors.

[0081] For example, four sets of measured distance values ​​and four sets of actual measurement errors obtained by four samplings are shown in the following table:

[0082]

[0083] Among them, in the above table, "DXY" is the actual measurement value, "EXY" is the actual measurement error, the digital "X" value represents the corresponding pixel area number, and the digital "Y" value represents the corresponding sampling number.

[0084] See also Figure 7 , Figure 7 A schematic diagram showing the swing error curve of the time-of-flight sensor in the embodiment of the present application is shown. According to the above data, it can be fitted to obtain Figure 7 The swing error of the time-of-flight sensor shown ultimately achieves the purpose of calibrating the swing error of the time-of-flight sensor.

[0085] In the embodiment of the present application, the present application adopts multiple demodulation signals with different delay phases for multiple pixel areas, and in each sampling process, a group of multiple measured distance values ​​corresponding to multiple pixel areas can be obtained, and a group of multiple actual measurement errors corresponding to multiple pixel areas can be obtained. Finally, after multiple measurements, multiple groups of measured distance data and multiple groups of actual error data can be obtained, so as to determine the swing error of the flight time sensor according to the multiple groups of measured distance values ​​and multiple groups of actual measurement errors. At the same time, since the actual measurement error is the measurement error corrected for the delay phase and / or the spatial distance after each sampling test object TEST moves, that is, the actual measurement error includes the measurement error caused by the delay phase and / or the spatial distance after each sampling test object TEST moves, it is conducive to ensuring the accuracy of the swing error calibration of the flight time sensor.

[0086] In some embodiments of the present application, the delayed phases of the Nth demodulated signal corresponding to the Nth sampling measurement and the Mth demodulated signal corresponding to the Mth sampling measurement of any pixel area are not equal to each other, N and M are integers greater than or equal to 1, and N and M are not equal to each other.

[0087] For example, see Figure 8 as well as Fig. 9 , Figure 8 A schematic diagram showing a modulation signal MS and a demodulation signal during the first sampling in an embodiment of the present application is shown, Fig. 9 A schematic diagram of the modulation signal MS and the demodulation signal during the second sampling in an embodiment of the present application is shown. For the pixel area PR1, during the first sampling, the delay phase between the demodulation signal DS1 corresponding to the pixel area PR1 and the modulation signal MS is T / 16, and during the second sampling, the delay phase between the demodulation signal DS1 corresponding to the pixel area PR1 and the modulation signal MS is T / 8.

[0088] For the pixel area PR2, at the first sampling, the delay phase between the demodulation signal DS2 corresponding to the pixel area PR2 and the modulation signal MS is 3T / 16, and at the second sampling, the delay phase between the demodulation signal DS1 corresponding to the pixel area PR1 and the modulation signal MS is 4T / 16. By analogy, the delay phases of the Nth demodulation signal corresponding to the Nth sampling measurement and the Mth demodulation signal corresponding to the Mth sampling measurement of any pixel area are not equal.

[0089] It should be noted that, since the delay phases of the Nth demodulated signal corresponding to the Nth sampling measurement and the Mth demodulated signal corresponding to the Mth sampling measurement of any pixel area are not equal, combined with the embodiment in which the delay phases of the demodulated signals corresponding to each pixel area PR1 are different, a large number of distance measurement values ​​and actual measurement errors at different spatial distances can be obtained, thereby making the swing error calibration of the time-of-flight sensor more accurate.

[0090] For example, Figure 8 as well as Fig. 9 For example, if the phase difference between the demodulated signals corresponding to adjacent pixel areas is 8 / T, and the position of the test object TEST is fixed, the distance measurement value obtained by secondary sampling is as shown in the following table:

[0091] Pixel area sampling times First sampling Second sampling PR1 D1+T / 16*c D1+2T / 16*c PR2 D1+3T / 16*c D1+4T / 16*c PR3 D1+5T / 16*c D1+6T / 16*c PR4 D1+7T / 16*c D1+8T / 16*c PR5 D1+9T / 16*c D1+10T / 16*c PR6 D1+11T / 16*c D1+12T / 16*c PR7 D1+13T / 16*c D1+14T / 16*c PR8 D1+15T / 16*c D1+16T / 16*c

[0092] It can be seen that even if the position of the test object TEST is fixed, by making the delayed phases of the Nth demodulated signal corresponding to the Nth sampling measurement of the pixel area and the Mth demodulated signal corresponding to the Mth sampling measurement unequal to each other, a large number of distance measurement values ​​at different spatial distances can be obtained, thereby making the swing error calibration of the time-of-flight sensor more accurate.

[0093] In some embodiments of the present application, the delay phase of each demodulated signal includes a local delay phase and a global delay phase relative to the modulation signal MS; in each sampling process, the global delay phase of each demodulated signal is equal, and the local delay phase of each demodulated signal is not equal.

[0094] For example, see Fig.10 , Fig.10 A schematic diagram of the modulation signal MS and the demodulation signal in an embodiment of the present application is shown, where the global delay phase of the demodulation signal DS1 corresponding to the pixel area PR1 is φA, and the local delay phase is zero; the global delay phase of the demodulation signal DS2 corresponding to the pixel area PR2 is φA, and the local delay phase is φB2; the global delay phase of the demodulation signal DS2 corresponding to the pixel area PR2 is φA, and the local delay phase is φB3, and so on.

[0095] It can be seen that although the global delay phase of each demodulated signal is equal to φA in each sampling process, since the local delay phase of each demodulated signal is not equal, the delay phases of multiple demodulated signals can be made different from each other. Therefore, in each sampling process, the measured distance value measured in each pixel area is different from each other, so that the time-of-flight sensor can obtain the swing error within a wide measurement distance.

[0096] In some embodiments of the present application, during multiple sampling processes, the position of the test object TEST remains unchanged; the global delay phases of the Nth demodulated signal corresponding to the Nth sampling measurement of any pixel area and the N+1th demodulated signal corresponding to the N+1th sampling measurement differ by a first preset time length; and the local delay phases of the Nth demodulated signal corresponding to the Nth sampling measurement of any pixel area and the N+1th demodulated signal corresponding to the N+1th sampling measurement are equal.

[0097] For example, see Fig.11 as well as Fig.12 , Fig.11 A schematic diagram showing a modulation signal MS and a demodulation signal during the first sampling in an embodiment of the present application is shown, Fig.12 A schematic diagram of the modulation signal MS and the demodulation signal during the second sampling in an embodiment of the present application is shown, wherein, during the first sampling, the global delay phases of the multiple demodulation signals DS1~DS8 corresponding to the pixel area PR1 to the pixel area PR8 are all T / 16, and the local delay phases of the pixel area DS1 to the pixel area DS8 during the first sampling are 0, T / 8, 2T / 8, 3T / 8, 4T / 8, 5T / 8, 6T / 8, and 7T / 8, respectively; and during the second sampling, the global delay phases of the multiple demodulation signals DS1~DS8 corresponding to the pixel area PR1 to the pixel area PR8 are all T / 8, and the local delay phases of the pixel area DS1 to the pixel area DS8 during the first sampling are still 0, T / 8, 2T / 8, 3T / 8, 4T / 8, 5T / 8, 6T / 8, and 7T / 8, respectively.

[0098] It can be seen that even if the position of the test object TEST remains unchanged, by making the global delay phases of the Nth demodulated signal corresponding to the Nth sampling measurement of any pixel area and the N+1th demodulated signal corresponding to the N+1th sampling measurement differ by a first preset time length, the delay phases of the Nth demodulated signal corresponding to the Nth sampling measurement of the pixel area and the Mth demodulated signal corresponding to the Mth sampling measurement can also be made unequal to each other, and ultimately a large number of distance measurement values ​​at different spatial distances can be obtained, which is beneficial for the time-of-flight sensor to obtain swing errors within a wide measurement distance.

[0099] It can be understood that the above embodiment is only for illustration, and the global delay phase of the demodulated signal corresponding to multiple samplings may not be equally spaced. For example, refer to the following table, in which the global delay phase of the demodulated signal for four samplings is T / 16, 2T / 16, 4T / 16, and 8T / 16 respectively.

[0100]

[0101] It should be noted that the local delay phases of the multiple demodulation signals DS1 to DS8 are only ideal values, and they usually have delay errors. For example, for the embodiment in which the local delay phase of the demodulation signal DS2 is T / 8, its true value may be 7T / 64. If it is not corrected, it may cause the swing error calibrated by the time-of-flight sensor to include the delay error. Therefore, in some embodiments of the present application, the actual measurement error is the measurement error after the local delay phase is corrected, which is conducive to ensuring the accuracy of the swing error calibration of the time-of-flight sensor.

[0102] In some embodiments of the present application, for example, in an embodiment where the position of the test object TEST remains unchanged, refer to Fig.13 , Fig.13 A schematic flow chart of determining multiple sets of measured distance data and multiple sets of actual error data in an embodiment of the present application is shown, wherein the steps of controlling multiple pixel areas based on multiple demodulation signals with different delay phases to perform multiple sampling on the reflected light RX returned from the test object TEST to obtain multiple sets of measured distance data and multiple sets of actual error data include:

[0103] Step S1301, determining the measured distance value corresponding to each pixel area according to the phase difference between the emitted light TX and the reflected light RX sampled by each pixel area in each sampling process.

[0104] For example, during the first sampling, the light intensity of the reflected light RX at the phases of 90°, 180°, 270°, and 360° of the modulation signal MS is sampled respectively through multiple demodulation signals DS1~DS8, and then the phase difference between the emitted light TX and the reflected light RX sampled by each pixel area is calculated, so as to determine the measured distance value corresponding to each pixel area at the first sampling; before starting the second sampling, the global delay phase of the multiple demodulation signals DS1~DS8 is changed, and then the light intensity of the reflected light RX at the phases of 90°, 180°, 270°, and 360° of the modulation signal MS is sampled respectively through multiple demodulation signals DS1~DS8 with changed global delay phases, and then the phase difference between the emitted light TX and the reflected light RX sampled by each pixel area is calculated, so as to determine the measured distance value corresponding to each pixel area at the first sampling, and so on. After multiple samplings, multiple sets of measured distance data can be obtained.

[0105] Step S1302, determining the actual measurement error corresponding to each pixel area according to the global delay phase of the demodulated signal corresponding to each pixel area in each sampling process, the actual spatial distance of each pixel area relative to the measured object, and the measured distance value corresponding to each pixel area.

[0106] It should be noted that since the position of the measured object remains unchanged, the actual spatial distance of the measured object after high-precision measurement is a known quantity that is basically error-free; at the same time, since the global delay phase of each demodulated signal is the same in each sampling process, even if there is an error in the global delay phase of each demodulated signal, it can be calculated into the error of the ideal local delay phase of the corresponding demodulated signal. Therefore, it is only necessary to eliminate the error corresponding to the fixed local delay phase of each demodulated signal to ensure the accuracy of the actual measurement error corresponding to each pixel area.

[0107] For example, the distance value measured by the same pixel in the same sampling process, the actual measurement error, the actual spatial distance, the spatial distance corresponding to the global delay phase, and the spatial distance corresponding to the ideal local delay phase satisfy the following formula:

[0108] E+DB=M0-D-DA

[0109] Among them, E is the actual measurement error, DB is the distance corresponding to the ideal local delay phase, M0 is the measured distance value, D is the actual spatial distance, and DA is the distance corresponding to the global delay phase.

[0110] It can be seen that M0, D, and DA are known quantities, and E and DB are unknown quantities with errors. However, since the present application involves multiple measurements, for the same pixel area PR, multiple sampling can obtain multiple E+DB values. Since the local delay phase of the Nth demodulated signal corresponding to the Nth sampling measurement of any pixel area is equal to the local delay phase of the N+1th demodulated signal corresponding to the N+1 sampling measurement, the DB value for each sampling is fixed, and then the multiple E+DB values ​​can be averaged to obtain the spatial distance corresponding to the actual local delay phase, and finally calculate the actual measurement error corresponding to each pixel area.

[0111] In some embodiments of the present application, see Fig.14 , Fig.14 A schematic flow chart of determining an actual measurement error in an embodiment of the present application is shown, wherein the step of determining the actual measurement error corresponding to each pixel area according to the global delay phase of the demodulated signal corresponding to each pixel area in each sampling process, the actual spatial distance of each pixel area relative to the measured object, and the measured distance value corresponding to each pixel area includes:

[0112] Step S1401, determining the ideal measurement error corresponding to each pixel area according to the global delay phase of the demodulated signal corresponding to each pixel area in each sampling process, the actual spatial distance of each pixel area relative to the measured object, and the measured distance value corresponding to each pixel area.

[0113] Specifically, the ideal measurement error EA of a pixel area in a certain sampling process can be calculated according to the following formula:

[0114] EA=E+DB=M0-D-DA

[0115] Wherein, E is the actual measurement error of a pixel area in a certain sampling process, M0 is the measured distance value of a pixel area in a certain sampling process, D is the actual spatial distance of a pixel area relative to the test object TEST in a certain sampling process, DA is the distance corresponding to the global delay phase of the demodulated signal of a pixel area in a certain sampling process, and DB is the distance corresponding to the ideal local delay phase of the demodulated signal of a pixel area in a certain sampling process.

[0116] It can be understood that the above formula is only for illustration, and those skilled in the art can make adjustments according to actual needs, such as setting fixed parameters according to empirical formulas.

[0117] Step S1402, determining the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area according to the ideal measurement error corresponding to the same pixel area in multiple sampling processes.

[0118] After obtaining the ideal measurement error, the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area can be determined based on the ideal measurement error corresponding to the same pixel area during multiple sampling processes. In some embodiments of the present application, the average measurement error corresponding to each pixel area can be determined for multiple ideal measurement errors corresponding to each pixel area, and the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area can be determined based on the average measurement error.

[0119] For example, the ideal measurement error and measurement distance obtained by the four-time sampling process are shown in the following table:

[0120]

[0121] Among them, in the above table, "DXY" is the actual measurement value, "EAXY" is the ideal measurement error, the digital "X" value represents the corresponding pixel area number, and the digital "Y" value represents the corresponding sampling number.

[0122] For the pixel region PR1, its average measurement error can be calculated according to the following formula:

[0123] ERP1=(EA11+EA12+EA11+EA12) / 4

[0124] For the pixel region PR2, its average measurement error can be calculated according to the following formula:

[0125] ERP2=(EA21+EA22+EA21+EA22) / 4

[0126] By analogy, the average measurement error of each pixel area can be obtained. Since the ideal measurement error actually includes the spatial distance corresponding to the local delay phase and the swing error of the time-of-flight sensor (that is, the actual measurement error), but the swing error of the time-of-flight sensor changes periodically between positive and negative at different distances, the above average measurement error can be considered to be the spatial distance corresponding to the actual local delay phase, thereby realizing the measurement of the spatial distance corresponding to the local delay phase.

[0127] It can be understood that the implementation method of determining the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area is not limited to this. For example, the above table data can also be fitted as follows: Fig.15 As shown in the figure, each curve represents a curve obtained by fitting multiple ideal measurement errors corresponding to a pixel area. Then, the spatial distance corresponding to the actual local delay phase can be determined by fitting the curve, and the following is obtained: Fig.16 The spatial distance corresponding to the actual local delay phase of each Shinjuku area is shown.

[0128] Step S1403 , according to the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area, the ideal measurement error corresponding to each pixel area is compensated to obtain the actual measurement error corresponding to each pixel area.

[0129] After obtaining the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area, the ideal measurement error corresponding to each pixel area can be compensated to obtain the actual measurement error corresponding to each pixel area. For example, the ideal measurement error of each pixel area is subtracted from the spatial distance corresponding to the actual local delay phase, and the following table is obtained:

[0130]

[0131] Among them, in the above table, "DXY" is the actual measurement value, "EAXY" is the ideal measurement error, "DBX" is the spatial distance corresponding to the actual local delay phase, the digital "X" value represents the corresponding pixel area number, and the digital "Y" value represents the corresponding sampling number.

[0132] It can be seen that the actual measurement error in the above table is the measurement error after correcting the local delay phase of the demodulated signal, that is, the actual measurement error includes the measurement error caused by the delay phase, which is helpful to ensure the accuracy of the swing error calibration of the time of flight sensor.

[0133] In some embodiments of the present application, during multiple sampling processes, the positions of the test object TEST are different from each other; and the delayed phase of the Nth demodulation signal corresponding to the Nth sampling measurement and the N+1th demodulation signal corresponding to the N+1th sampling measurement of any pixel area is equal. In other words, during multiple sampling processes, the position of the test object TEST is changed, but the multiple demodulation signals are unchanged during each sampling.

[0134] In some embodiments of the present application, for example, in embodiments where the position of the test object TEST is changed during multiple sampling processes, see Fig.17 , Fig.17 A schematic flow chart of determining the actual measurement error in an embodiment of the present application is shown, wherein the step of determining the actual measurement error corresponding to each pixel area according to the global delay phase of the demodulated signal corresponding to each pixel area in each sampling process, the actual spatial distance of each pixel area relative to the measured object, and the measured distance value corresponding to each pixel area includes:

[0135] Step S1701, determining the measured distance value corresponding to each pixel area according to the phase difference between the emitted light TX and the reflected light RX sampled by each pixel area in each sampling process.

[0136] Step S1702, determining the actual measurement error corresponding to each pixel area according to the actual spatial distance of each pixel area relative to the measured object during the delay phase in each sampling process and the measured distance value corresponding to each pixel area.

[0137] It should be noted that since the delay phase of each demodulated signal is the same in each sampling process, the delay phase becomes a known quantity with basically no error after high-precision measurement. Therefore, only the corresponding error caused by the movement of the test object TEST during each sampling is needed to ensure the accuracy of the actual measurement error corresponding to each pixel area.

[0138] For example, the distance value, actual measurement error, actual spatial distance, and spatial distance corresponding to the delay phase of the same pixel in the same sampling process satisfy the following formula:

[0139] E+D=M0-DC

[0140] Among them, E is the actual measurement error, D is the actual spatial distance, M0 is the measured distance value, and DC is the distance corresponding to the delayed phase.

[0141] It can be seen that M0 and DC are known quantities, and E and D are unknown quantities with errors. However, since the present application involves multiple measurements, for the same pixel area PR, multiple samplings can obtain multiple E+D values. Since the change distances of multiple pixel areas relative to the test object TEST are the same during one sampling process, the D value is fixed each time it is sampled. The multiple E+D values ​​can then be averaged to obtain the actual spatial distance moved by the test object TEST, and finally calculate the actual measurement error corresponding to each pixel area.

[0142] In some embodiments of the present application, see Fig.18 , Fig.18 A schematic flow chart of determining an actual measurement error in an embodiment of the present application is shown, wherein the step of determining the actual measurement error corresponding to each pixel area according to the actual spatial distance of each pixel area relative to the measured object in the delayed phase and the measured distance value corresponding to each pixel area includes:

[0143] Step S1801, determining the ideal measurement error corresponding to each pixel area according to the actual spatial distance of each pixel area relative to the measured object in the delayed phase and the measured distance value corresponding to each pixel area.

[0144] Specifically, the ideal measurement error EA of a pixel area in a certain sampling process can be calculated according to the following formula:

[0145] EA=E+D=M0-DC

[0146] Among them, E is the actual measurement error of a pixel area in a certain sampling process, M0 is the measured distance value of a pixel area in a certain sampling process, D is the actual spatial distance of a pixel area relative to the test object TEST in a certain sampling process, and DC is the spatial distance corresponding to the delay phase of the demodulated signal of a pixel area in a certain sampling process.

[0147] Step S1802, determining the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area according to the ideal measurement error corresponding to the same pixel area in multiple sampling processes.

[0148] After obtaining the ideal measurement error, the spatial distance corresponding to the actual local delay phase of the corresponding demodulated signal (i.e., the actual spatial distance of each pixel area relative to the test object TEST) can be determined based on the ideal measurement error corresponding to the same pixel area during multiple sampling processes. In some embodiments of the present application, the average measurement error corresponding to each pixel area can be determined for each of the multiple ideal measurement errors corresponding to each pixel area; the actual spatial distance of each pixel area relative to the test object TEST can be determined based on the average measurement error.

[0149] For example, the ideal measurement error and measurement distance obtained by the four-time sampling process are shown in the following table:

[0150]

[0151] Among them, in the above table, "DXY" is the actual measurement value, "EAXY" is the ideal measurement error, the digital "X" value represents the corresponding pixel area number, and the digital "Y" value represents the corresponding sampling number.

[0152] For the pixel region PR1, its average measurement error can be calculated according to the following formula:

[0153] ERP1=(EA11+EA12+EA11+EA12) / 4

[0154] For the pixel region PR2, its average measurement error can be calculated according to the following formula:

[0155] ERP2=(EA21+EA22+EA21+EA22) / 4

[0156] By analogy, the average measurement error of each pixel area can be obtained. Since the ideal measurement error actually includes the actual spatial distance of each pixel area relative to the test object TEST and the swing error of the time-of-flight sensor (that is, the actual measurement error), but the swing error of the time-of-flight sensor changes periodically between positive and negative at different distances, the above average measurement error can be considered as the actual spatial distance of each pixel area relative to the test object TEST, thereby realizing the measurement of the spatial distance corresponding to the local delay phase.

[0157] Step S1803, compensating the ideal measurement error corresponding to each pixel area according to the spatial distance corresponding to the actual local delay phase of the corresponding demodulated signal, so as to obtain the actual measurement error corresponding to each pixel area.

[0158] After obtaining the actual spatial distance of each pixel area relative to the test object TEST, the ideal measurement error corresponding to each pixel area can be compensated to obtain the actual measurement error corresponding to each pixel area. For example, refer to the following table:

[0159]

[0160] Among them, in the above table, "DXY" is the actual measurement value, "EAXY" is the ideal measurement error, "DX" is the actual spatial distance of the pixel area relative to the test object TEST, the digital "X" value represents the corresponding pixel area number, and the digital "Y" value represents the corresponding sampling number.

[0161] It can be seen that the actual measurement error in the above table is the measurement error after correction for the spatial distance after each sampling test object TEST moves. That is to say, the actual measurement error includes the measurement error caused by the spatial distance after each sampling test object TEST moves. Therefore, it is helpful to ensure the accuracy of the swing error calibration of the time-of-flight sensor.

[0162] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the detailed description of other embodiments above, and will not be repeated here.

[0163] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0164] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0165] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this application, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0166] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0167] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this application is hereby incorporated by reference in its entirety, except for application history documents that are inconsistent with or conflicting with the content of this application, and documents that limit the broadest scope of the claims of this application (currently or later attached to this application). It should be noted that if the descriptions, definitions, and / or use of terms in the accompanying materials of this application are inconsistent or conflicting with the content described in this application, the descriptions, definitions, and / or use of terms in this application shall prevail.

[0168] The above is a detailed introduction to an error calibration method and a time-of-flight sensor provided in an embodiment of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. An error calibration method, characterized in that: Applied to a time-of-flight sensor having a plurality of pixel areas, the error calibration method comprises: Control the light source to generate emitted light based on the modulation signal to illuminate the test object; Controlling the plurality of pixel areas to perform multiple sampling of reflected light returned from the test object based on multiple demodulation signals with different delay phases, so as to obtain multiple groups of measured distance data and multiple groups of actual error data, wherein each group of the measured distance data includes multiple measured distance values ​​corresponding to the plurality of pixel areas one by one, and each group of the actual error data includes multiple actual measured errors corresponding to the plurality of pixel areas one by one; determining a swing error of the time-of-flight sensor according to the measured distance value of each set of the measured distance data and the actual measured error of each set of the actual error data; The actual measurement error is a measurement error after correction of the delay phase and / or the spatial distance after the test object moves in each sampling.

2. The error calibration method according to claim 1, characterized in that: The delayed phases of the Nth demodulated signal corresponding to the Nth sampling measurement and the Mth demodulated signal corresponding to the Mth sampling measurement of any pixel area are not equal to each other; or The spatial distance of any pixel region relative to the test object during the Nth sampling measurement is not equal to the spatial distance of any pixel region relative to the test object during the N+1th sampling measurement; Wherein, N and M are integers greater than or equal to 1, and N and M are not equal.

3. The error calibration method according to claim 1, characterized in that: The delay phase of each of the demodulated signals includes a local delay phase and a global delay phase relative to the modulated signal; In each sampling process, the global delay phase between each of the demodulated signals is equal, and the local delay phase between each of the demodulated signals is unequal.

4. The error calibration method according to claim 3, characterized in that: During multiple sampling processes, the position of the test object remains unchanged; The global delay phases of the Nth demodulated signal corresponding to the Nth sampling measurement and the N+1th demodulated signal corresponding to the N+1th sampling measurement of any pixel area differ by a first preset time length; Furthermore, the local delay phases of the Nth demodulated signal corresponding to the Nth sampling measurement and the N+1th demodulated signal corresponding to the N+1th sampling measurement of any pixel region are equal.

5. The error calibration method according to claim 4, characterized in that: The actual measurement error is the measurement error after the local delay phase is corrected.

6. The error calibration method according to claim 5, characterized in that: The steps of controlling the plurality of pixel areas based on the plurality of demodulated signals with different delay phases to perform multiple sampling on the reflected light returned from the test object to obtain multiple sets of measured distance data and multiple sets of actual error data include: Determine the measured distance value corresponding to each pixel area according to the phase difference between the emitted light and the reflected light sampled by each pixel area during each sampling process; The actual measurement error corresponding to each pixel area is determined according to the global delay phase of the demodulated signal corresponding to each pixel area in each sampling process, the actual spatial distance of each pixel area relative to the measured object, and the measured distance value corresponding to each pixel area.

7. The error calibration method according to claim 6, characterized in that: The step of determining the actual measurement error corresponding to each pixel area according to the global delay phase of the demodulated signal corresponding to each pixel area in each sampling process, the actual spatial distance of each pixel area relative to the measured object, and the measured distance value corresponding to each pixel area comprises: Determine an ideal measurement error corresponding to each pixel area according to the global delay phase of the demodulated signal corresponding to each pixel area in each sampling process, the actual spatial distance of each pixel area relative to the measured object, and the measured distance value corresponding to each pixel area; Determine the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area according to the ideal measurement error corresponding to the same pixel area during multiple sampling processes; According to the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area, the ideal measurement error corresponding to each pixel area is compensated to obtain the actual measurement error corresponding to each pixel area.

8. The error calibration method according to claim 1, characterized in that: During multiple sampling processes, the test object positions are different from each other; Furthermore, the delayed phase of the Nth demodulated signal corresponding to the Nth sampling measurement of any pixel region is equal to the delayed phase of the N+1th demodulated signal corresponding to the N+1th sampling measurement.

9. The error calibration method according to claim 8, characterized in that: The steps of controlling the plurality of pixel areas based on the plurality of demodulated signals with different delay phases to perform multiple sampling on the reflected light returned from the test object to obtain multiple sets of measured distance data and multiple sets of actual error data include: Determine the measured distance value corresponding to each pixel area according to the phase difference between the emitted light and the reflected light sampled by each pixel area during each sampling process; According to the actual spatial distance of each pixel area relative to the measured object during the delay phase in each sampling process and the measured distance value corresponding to each pixel area, the actual measurement error corresponding to each pixel area is determined.

10. The error calibration method according to claim 9, characterized in that: The step of determining the actual measurement error corresponding to each pixel area according to the actual spatial distance of each pixel area relative to the measured object during each sampling process and the measured distance value corresponding to each pixel area comprises: Determine an ideal measurement error corresponding to each pixel area according to the actual spatial distance of each pixel area relative to the measured object and the measured distance value corresponding to each pixel area; Determine the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area according to the ideal measurement error corresponding to the same pixel area during multiple sampling processes; According to the spatial distance corresponding to the actual local delay phase of the demodulated signal corresponding to each pixel area, the ideal measurement error corresponding to each pixel area is compensated to obtain the actual measurement error corresponding to each pixel area.

11. A time-of-flight sensor, characterized in that: include: A light source, the light source is used to generate an emission light according to a modulation signal; A plurality of pixel areas, wherein the plurality of pixel areas are used to sample reflected light rays returned from the illuminated object to obtain a measured distance value; Wherein, the time-of-flight sensor is used to calibrate the measured distance value according to the swing error obtained by the method according to any one of claims 1 to 10.

12. The time-of-flight sensor according to claim 11, wherein: The time-of-flight sensor further includes a delay module configured to generate a plurality of demodulated signals.

Images