A Time-of-Flight Sensor Calibration Method, Device, and Storage Medium

Abstract

The present disclosure relates to a time-of-flight sensor calibration method, apparatus, and storage medium. The time-of-flight sensor calibration method includes: controlling the time-of-flight sensor to measure the distance of a first calibration distance; during the measurement of the first calibration distance, performing crosstalk calibration on each acquisition element in the acquisition element array to obtain the crosstalk calibration parameters of the acquisition element array, and performing zero-offset calibration on the acquisition element array to obtain zero-offset calibration parameters; and calibrating the time-of-flight sensor based on the crosstalk calibration parameters and the zero-offset calibration parameters. Through the present disclosure, calibration of a time-of-flight sensor having an acquisition element array can be achieved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of focus adjustment of image acquisition devices, and in particular, to a calibration method, apparatus, and storage medium for a time-of-flight sensor. Background Art

[0002] With the development of science and technology, a time-of-flight (TOF) sensor, as a common means of precise focus adjustment, is well-known to people. However, during the process of using a TOF sensor for focus adjustment, the focus adjustment accuracy is often affected by the zero offset and crosstalk existing in the TOF sensor. In related technologies, it is usually necessary to perform zero offset calibration and crosstalk calibration on the TOF sensor, so that the TOF can obtain relatively accurate time-of-flight data.

[0003] In related technologies, it is possible to calibrate a TOF sensor with a single acquisition element (for example, a single photon avalanche diode (SPAD)), but it is not possible to calibrate a TOF sensor with an array of acquisition elements (for example, an SPAD array). Summary of the Invention

[0004] To overcome the problems existing in related technologies, the present disclosure provides a calibration method, apparatus, and storage medium for a time-of-flight sensor.

[0005] According to a first aspect of an embodiment of the present disclosure, there is provided a calibration method for a time-of-flight sensor, characterized in that a single photon avalanche diode acquisition element array is installed in a receiver of the time-of-flight sensor, and the calibration method for the time-of-flight sensor includes:

[0006] Controlling the time-of-flight sensor to measure the distance to a first calibration distance; during the process of measuring the first calibration distance, performing crosstalk calibration on each acquisition element in the acquisition element array to obtain crosstalk calibration parameters of the acquisition element array, and performing zero offset calibration on the acquisition element array to obtain zero offset calibration parameters; and calibrating the time-of-flight sensor based on the crosstalk calibration parameters and the zero offset calibration parameters.

[0007] In one implementation, the crosstalk calibration for each acquisition element in the acquisition element array includes: taking any one acquisition element in the acquisition element array as a reference acquisition element, performing crosstalk calibration on the reference acquisition element to obtain reference crosstalk calibration parameters; determining the difference degree correspondence between the reference acquisition element and other acquisition elements in the acquisition element array based on the acquisition element reference difference degree correspondence, and respectively determining the crosstalk calibration parameters of each acquisition element in the other acquisition elements based on the difference degree correspondence and the reference crosstalk calibration parameters; using the reference crosstalk calibration parameters and the crosstalk calibration parameters of each acquisition element in the other acquisition elements as the crosstalk calibration parameters of the acquisition element array.

[0008] In one implementation, the acquisition element reference difference degree correspondence is determined in the following manner: controlling multiple time-of-flight sensors having the acquisition element array to measure the distance to a second calibration distance; during the process of the multiple time-of-flight sensors measuring the second calibration distance, acquiring the ranging pulses of each acquisition element in the acquisition element array of each time-of-flight sensor; for each time-of-flight sensor among the multiple time-of-flight sensors, respectively determining the difference degree correspondence of each acquisition element in the acquisition element array based on the difference degree between the ranging pulses of the respective acquisition elements, to obtain the acquisition element difference degree correspondences of the multiple time-of-flight sensors; and normalizing the acquisition element difference degree correspondences of the multiple time-of-flight sensors to obtain the acquisition element reference difference degree correspondence.

[0009] In one implementation, the second calibration distance satisfies that each acquisition element in the acquisition element arrays of the multiple time-of-flight sensors receives a ranging pulse, and the received ranging pulses do not overlap.

[0010] In one implementation, the determining the difference degree correspondence of each acquisition element in the acquisition element array based on the difference degree between the ranging pulses of the respective acquisition elements includes: obtaining the ranging pulse intensities of each acquisition element in the acquisition element array, determining the proportional relationship between the ranging pulse intensities; and determining the difference degree correspondence of each acquisition element in the acquisition element array based on the proportional relationship between the ranging pulse intensities.

[0011] In one implementation, performing zero-offset calibration on the acquisition element array to obtain zero-offset calibration parameters includes: obtaining the time-of-flight data of any one acquisition element in the acquisition element array; and performing zero-offset calibration based on the time-of-flight data to obtain zero-offset calibration parameters.

[0012] In one implementation, controlling the time-of-flight sensor to measure the distance to the first calibration distance includes: fixing a standard card made of a material with a standard reflectivity at the first calibration distance position; controlling the time-of-flight sensor to emit a ranging pulse towards the standard card, and performing ranging based on the ranging pulse reflected from the standard card to the acquisition element array; wherein the standard reflectivity is such that the ranging pulses reflected from the standard card to the acquisition element do not overlap.

[0013] According to a second aspect of the embodiments of the present disclosure, there is provided a time-of-flight sensor calibration device, characterized in that a single-photon avalanche diode acquisition element array is installed in the receiver of the time-of-flight sensor, and the time-of-flight sensor calibration device includes:

[0014] A control unit for controlling the time-of-flight sensor to measure the distance to the first calibration distance; a calibration unit for, during the process of measuring the distance to the first calibration distance, respectively performing crosstalk calibration on each acquisition element in the acquisition element array to obtain crosstalk calibration parameters of the acquisition element array, and performing zero-offset calibration on the acquisition element array to obtain zero-offset calibration parameters; and calibrating the time-of-flight sensor based on the crosstalk calibration parameters and the zero-offset calibration parameters.

[0015] In one implementation, the calibration unit performs crosstalk calibration on each acquisition element in the acquisition element array in the following manner: taking any one acquisition element in the acquisition element array as a reference acquisition element, and performing crosstalk calibration on the reference acquisition element to obtain reference crosstalk calibration parameters; determining the difference degree correspondence relationship between the reference acquisition element and other acquisition elements in the acquisition element array based on the acquisition element reference difference degree correspondence relationship, and respectively determining the crosstalk calibration parameters of each acquisition element in the other acquisition elements based on the difference degree correspondence relationship and the reference crosstalk calibration parameters; and taking the reference crosstalk calibration parameters and the crosstalk calibration parameters of each acquisition element in the other acquisition elements as the crosstalk calibration parameters of the acquisition element array.

[0016] In one implementation, the calibration unit determines the corresponding relationship of the reference difference degree of the acquisition elements in the following manner: controlling a plurality of time-of-flight sensors having the acquisition element array to measure the distance to a second calibration distance; during the process of the plurality of time-of-flight sensors measuring the second calibration distance, acquiring the ranging pulses of each acquisition element in the acquisition element array of each time-of-flight sensor; for each time-of-flight sensor among the plurality of time-of-flight sensors, respectively determining the corresponding relationship of the difference degree of each acquisition element in the acquisition element array based on the difference degree between the ranging pulses of the respective acquisition elements, to obtain the corresponding relationships of the difference degrees of the acquisition elements of the plurality of time-of-flight sensors; and normalizing the corresponding relationships of the difference degrees of the acquisition elements of the plurality of time-of-flight sensors to obtain the corresponding relationship of the reference difference degree of the acquisition elements.

[0017] In one implementation, the second calibration distance is such that each acquisition element in the acquisition element array of the plurality of time-of-flight sensors receives a ranging pulse, and the received ranging pulses do not overlap.

[0018] In one implementation, the calibration unit determines the corresponding relationship of the difference degree of each acquisition element in the acquisition element array based on the difference degree between the ranging pulses of the respective acquisition elements in the following manner: obtaining the ranging pulse intensities of each acquisition element in the acquisition element array, and determining the proportional relationship between the ranging pulse intensities; and determining the corresponding relationship of the difference degree of each acquisition element in the acquisition element array based on the proportional relationship between the ranging pulse intensities.

[0019] In one implementation, the calibration unit calibrates the zero offset of the acquisition element array in the following manner to obtain zero offset calibration parameters: obtaining the time-of-flight data of any one acquisition element in the acquisition element array; and performing zero offset calibration based on the time-of-flight data to obtain zero offset calibration parameters.

[0020] In one implementation, the calibration unit controls the time-of-flight sensor to measure the distance to a first calibration distance in the following manner: fixing a standard card with a standard reflectivity material at the first calibration distance position; controlling the time-of-flight sensor to emit a ranging pulse towards the standard card, and performing distance measurement based on the ranging pulse reflected by the standard card to the acquisition element array; wherein the standard reflectivity is such that the ranging pulses reflected by the standard card to the acquisition elements do not overlap.

[0021] According to the third aspect of the embodiments of the present disclosure, there is provided a time-of-flight sensor calibration device, including:

[0022] a processor; and a memory for storing instructions executable by the processor;

[0023] Wherein, the processor is configured to execute the time-of-flight sensor calibration method described in the first aspect or any one of the embodiments of the first aspect.

[0024] According to a fourth aspect of the embodiments of the present disclosure, there is provided a storage medium storing instructions that, when executed by a processor, enable the processor to execute the time-of-flight sensor calibration method described in the first aspect or any one of the embodiments of the first aspect.

[0025] The technical solutions provided by the embodiments of the present disclosure may include the following beneficial effects: controlling the TOF sensor to measure the distance of a standard card that meets the criterion of non-overlapping ranging pulses, and during the distance measurement process, respectively performing crosstalk calibration on each acquisition element in the acquisition element array to obtain the crosstalk calibration parameters of the acquisition element array, and performing zero-offset calibration on the acquisition element array to obtain the zero-offset calibration parameters. In this way, the TOF sensor can be calibrated by the obtained crosstalk calibration parameters and zero-offset calibration parameters to achieve the calibration of the TOF sensor with an acquisition element array.

[0026] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure.

[0028] Figure 1 is a calibration flowchart of a TOF sensor with a single acquisition element shown according to an exemplary embodiment.

[0029] Figure 2 is a flowchart of a TOF sensor calibration method shown according to an exemplary embodiment.

[0030] Figure 3 is a flowchart of a method for determining the correspondence relationship of the reference difference degree of acquisition elements shown according to an exemplary embodiment.

[0031] Figure 4 is a schematic diagram of a TOF sensor receiver and the correspondence relationship of the reference difference degree of acquisition elements shown according to an exemplary embodiment.

[0032] Figure 5 is a flowchart of a method for performing crosstalk calibration on an acquisition element array shown according to an exemplary embodiment.

[0033] Figure 6It is a flowchart of a method for zero - point offset calibration of a collection element array shown according to an exemplary embodiment.

[0034] Figure 7 It is a calibration flowchart of a TOF sensor with a rectangular array of collection elements shown according to an exemplary embodiment.

[0035] Figure 8 It is a schematic diagram of a scenario for calibrating a TOF sensor shown according to an exemplary embodiment.

[0036] Figure 9 It is a block diagram of a TOF sensor calibration device shown according to an exemplary embodiment.

[0037] Figure 10 It is a block diagram of a device for calibrating a time - of - flight sensor shown according to an exemplary embodiment. Detailed implementation manners

[0038] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the present disclosure. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0039] The time - of - flight sensor calibration method provided by the embodiments of the present disclosure can be applied to scenarios of focusing for handheld, fixed, and movable image acquisition devices. Among them, the image acquisition device can be, for example, an image acquisition device such as a mobile phone, a digital camera, a tablet pad, and a laptop computer.

[0040] In the related art, a TOF sensor is usually used for precise focusing of an image acquisition device. A TOF sensor is a device that measures the flight time of a signal. It emits infrared light to a target object through an infrared laser emitter, and the infrared receiver receives the light reflected by the target object. Since the speed of its emitted signal and received signal is constant, the distance between the emission location and the target object can be calculated by determining the flight time of the signal from emission to reception. In the related art, there are various types of TOF sensors with focusing functions. For example, it can be a TOF sensor with a single collection element. Of course, it can also be a matrix - type TOF sensor with m * n collection elements. Among them, the matrix - type TOF sensor can be used for precise focusing of a camera. Since it has multiple collection elements, the focusing range of the image acquisition device can be further increased. Among them, the above - mentioned collection element can be a SPAD.

[0041] The TOF sensors of image acquisition devices are usually assembled under a glass cover plate and blocked by ink. Due to the performance differences between TOF sensors, the assembly positions of TOF sensors, the distance (airgap) from the TOF sensors to the glass cover plate, the ink transmittance, and the differences in the reflectivity of the target object, zero offset (offset) and crosstalk (x-talk) will occur in the TOF sensors, thereby affecting the focusing accuracy of the TOF sensors.

[0042] In related technologies, it is possible to calibrate a TOF sensor with a single acquisition element. For example, as Figure 1 shown, at the time of factory assembly on the production line, crosstalk calibration and zero offset calibration can be performed on a TOF sensor with a single acquisition element. And after passing the test verification, the calibration data is stored in the storage chip. When using the calibrated TOF sensor for focusing, the calibration data in the storage chip can be called to compensate the real-time ranging result. However, in related technologies, it is impossible to calibrate a TOF sensor device with a rectangular array of acquisition elements.

[0043] In view of this, the embodiments of the present disclosure provide a TOF sensor calibration method. Crosstalk calibration is performed on the acquisition elements in the acquisition element array, and zero offset calibration is performed on the acquisition elements in the acquisition element array to obtain the crosstalk calibration parameters and zero offset calibration parameters of the TOF sensor. The TOF sensor is calibrated by the obtained crosstalk calibration parameters and zero offset calibration parameters to achieve the calibration of the TOF sensor with a rectangular array of acquisition elements.

[0044] Figure 2 is a flowchart of a TOF sensor calibration method shown according to an exemplary embodiment. As Figure 2 shown, it includes the following steps.

[0045] In step S11, the TOF sensor is controlled to measure the distance to the first calibration distance.

[0046] In the embodiments of the present disclosure, controlling the TOF sensor to perform ranging may be to emit a ranging pulse through the transmitter of the TOF sensor and receive the emitted ranging pulse through the receiver (the acquisition element array installed in the receiver) of the TOF sensor, so as to obtain the flight time data. In one example, the first calibration distance may be any distance that satisfies the ranging conditions of the TOF sensor.

[0047] In step S12, during the measurement of the first calibration distance, crosstalk calibration is respectively performed on each acquisition element in the acquisition element array to obtain the crosstalk calibration parameters of the acquisition element array, and zero offset calibration is performed on the acquisition element array to obtain the zero offset calibration parameters.

[0048] In step S13, calibrate the TOF sensor based on the crosstalk calibration parameter and the zero-offset calibration parameter.

[0049] In the embodiments of the present disclosure, crosstalk calibration is performed on each acquisition element in the acquisition element array of the TOF sensor to obtain the crosstalk calibration parameter of the acquisition element array. Zero-offset calibration is performed on the acquisition element array to obtain the zero-offset calibration parameter of the acquisition element array. By using the obtained crosstalk calibration parameter and zero-offset calibration parameter to calibrate the TOF sensor, it is possible to calibrate the TOF sensor having an acquisition element array.

[0050] In one example, controlling the TOF sensor to measure the distance to the first calibration distance may be to fix a standard card with a standard reflectivity material at the first calibration distance position. Control the transmitter of the TOF sensor to emit a ranging pulse to the standard card, and the ranging pulse reflected by the standard card to the receiver (the acquisition element array installed in the receiver) of the TOF sensor. Among them, the standard reflectivity is such that the ranging pulses reflected by the standard card to the acquisition elements do not overlap.

[0051] In the embodiments of the present disclosure, the difference degree correspondence relationship between the acquisition elements in the acquisition element array can be determined in advance. When performing crosstalk calibration on each acquisition element in the acquisition element array, any acquisition element in the acquisition element array can be used as a reference acquisition element, and crosstalk calibration is performed on the reference acquisition element to obtain the crosstalk calibration parameter of the reference acquisition element. By using the crosstalk calibration parameter of the reference acquisition element and the difference degree correspondence relationship between the acquisition elements in the acquisition element array determined in advance, crosstalk calibration is performed on all the acquisition elements in the acquisition element array except the reference acquisition element, so as to obtain the crosstalk calibration parameters of all the acquisition elements.

[0052] In the embodiments of the present disclosure, for the sake of convenient description, the difference degree correspondence relationship used for crosstalk calibration of the acquisition element array is referred to as the acquisition element reference difference degree correspondence relationship. In one implementation manner, the acquisition element reference difference degree correspondence relationship can be determined in the following manner.

[0053] Figure 3 is a flowchart of a method for determining the acquisition element reference difference degree correspondence relationship shown according to an exemplary embodiment, as Figure 3 shown, including the following steps:

[0054] In step S21, control multiple TOF sensors having an acquisition element array to measure the distance to the second calibration distance.

[0055] In the embodiments of the present disclosure, the second calibration distance may be a calibration distance that satisfies the condition that each acquisition element in the acquisition element array of multiple TOF sensors receives a ranging pulse and the received ranging pulses do not overlap, so as to accurately obtain the corresponding relationship of the differences between each acquisition element.

[0056] In step S22, during the ranging of the second calibration distance by multiple TOF sensors, the ranging pulses of each acquisition element in the acquisition element array of each TOF sensor are acquired.

[0057] In step S23, for each TOF sensor among the multiple TOF sensors, based on the difference degree between the ranging pulses of each acquisition element, the corresponding relationship of the difference degrees of each acquisition element in the acquisition element array is determined, and the corresponding relationship of the difference degrees of the acquisition elements of multiple TOF sensors is obtained.

[0058] In step S24, the corresponding relationship of the difference degrees of the acquisition elements of multiple TOF sensors is normalized to obtain the corresponding relationship of the reference difference degrees of the acquisition elements.

[0059] In one example, using multiple TOF sensors to perform ranging of the second calibration distance and normalizing the obtained multiple sets of corresponding relationships of the difference degrees of the acquisition elements can reduce the error caused by the differences between devices, thereby further improving the accuracy of the corresponding relationship of the difference degrees of the acquisition elements.

[0060] In the embodiments of the present disclosure, the receiver of the TOF sensor may be an acquisition element array composed of m*n (m can be understood as the number of rows of the acquisition element rectangular array, and n can be understood as the number of columns of the acquisition element rectangular array) acquisition elements.

[0061] The TOF sensor calibration method provided by the embodiments of the present disclosure pre-determines the corresponding relationship of the reference difference degrees of the acquisition elements. Figure 4 It is a schematic diagram of a TOF sensor receiver and the corresponding relationship of the reference difference degrees of the acquisition elements (crosstalk array shape) shown according to an exemplary embodiment. As Figure 4 shown, each square in the TOF receiving surface can be understood as an acquisition element, each column in the corresponding relationship of the reference difference degrees of the acquisition elements can be understood as the ranging pulse acquired by each acquisition element, and the column height can be understood as the intensity of the ranging pulse acquired by the acquisition element.

[0062] In one implementation manner, the intensity of the ranging pulse of each acquisition element in the acquisition element array can be acquired, and the proportional relationship between the intensities of the ranging pulses acquired by each acquisition element can be determined. In one example, the corresponding relationship of the difference degrees of each acquisition element in the acquisition element array can be determined through the proportional relationship between the intensities of the ranging pulses acquired by each acquisition element.

[0063] In the embodiments of the present disclosure, during the process of ranging using a TOF sensor, crosstalk calibration can be performed on one of the acquisition element arrays, and crosstalk calibration can be performed on all other acquisition elements based on the corresponding relationship of the acquisition element reference difference.

[0064] In the TOF sensor calibration method provided by the embodiments of the present disclosure, crosstalk calibration can be performed on the acquisition element array of the TOF sensor based on the corresponding relationship of the acquisition element reference difference.

[0065] In the embodiments of the present disclosure, during the process of ranging at the first calibration distance, crosstalk calibration can be first performed on one of the acquisition element arrays, and then, based on the corresponding relationship of the acquisition element reference difference, the corresponding relationship of the difference between this acquisition element and all other acquisition elements in the acquisition element array can be determined, so as to perform crosstalk calibration on all the acquisition elements in the acquisition element array.

[0066] Figure 5 It is a flowchart of a method for performing crosstalk calibration on an acquisition element array shown according to an exemplary embodiment, as Figure 5 shown, and includes the following steps:

[0067] In step S31, any one of the acquisition elements in the acquisition element array is used as a reference acquisition element, and crosstalk calibration is performed on the reference acquisition element to obtain reference crosstalk calibration parameters.

[0068] In step S32, based on the corresponding relationship of the acquisition element reference difference, the corresponding relationship of the difference between the reference acquisition element and other acquisition elements in the acquisition element array is determined, and based on the corresponding relationship of the difference and the reference calibration parameters, the crosstalk calibration parameters of each acquisition element in other acquisition elements are respectively determined.

[0069] In step S33, the reference crosstalk calibration parameters and the crosstalk calibration parameters of each acquisition element in other acquisition elements are used as the crosstalk calibration parameters of the acquisition element array.

[0070] In one embodiment, during the process of ranging at the first calibration distance, the flight time data of any one of the acquisition elements in the acquisition element array can be obtained, and zero-point offset calibration can be performed through the flight time data, so as to obtain zero-point offset calibration parameters.

[0071] Figure 6 It is a flowchart of a method for performing zero-point offset calibration on an acquisition element array shown according to an exemplary embodiment.

[0072] In step S41, the flight time data of any one of the acquisition elements in the acquisition element array is obtained.

[0073] In step S42, zero-offset calibration is performed based on the time-of-flight data to obtain zero-offset calibration parameters.

[0074] In one example, the ranging value of the TOF sensor can be determined from the collected time-of-flight data, and this ranging value can be compared with the actual value of the TOF sensor at the first calibration distance, thereby determining the zero-offset calibration parameters.

[0075] In an embodiment of the present disclosure, after calibrating the TOF sensor with the crosstalk calibration parameters and the zero-offset calibration parameters, the focusing accuracy of the TOF sensor can be tested and verified. If the accuracy meets the usage requirements, the calibration data of the TOF sensor is stored in the storage chip of the image acquisition device to which the TOF sensor belongs.

[0076] Figure 7 It is a calibration flowchart of a TOF sensor having a rectangular array of acquisition elements shown according to an exemplary embodiment. As Figure 7 shown, the corresponding relationship between the reference difference degrees of the acquisition elements of the TOF sensor is determined in advance. Crosstalk calibration is performed on the TOF sensor to obtain the crosstalk calibration parameters of the TOF sensor. Zero-offset calibration is performed on the TOF sensor to obtain the zero-offset calibration parameters of the TOF sensor. The obtained crosstalk calibration parameters and zero-offset calibration parameters are used to calibrate the TOF sensor to obtain the calibration data of the TOF sensor. After the test and verification are passed, the calibration data of the TOF sensor is stored in the storage chip. When performing ranging with the TOF sensor subsequently, data calibration can be performed based on this calibration data.

[0077] Embodiments of the present disclosure will hereinafter describe the TOF sensor calibration process involved in the above embodiments in combination with practical applications.

[0078] Figure 8 It is a schematic diagram of a scenario for calibrating a TOF sensor shown according to an exemplary embodiment. As Figure 8As shown, ranging pulses can be emitted by the emitter of the TOF sensor, the ranging pulses emitted by the TOF sensor are reflected by the standard reflector 1 located at the L1 distance (the second calibration distance), and the ranging pulses are received by the receiver of the TOF sensor (the receiver with an array of acquisition elements). Among them, the L1 distance should satisfy that each acquisition element of the receiver with an array of acquisition elements can receive the ranging pulses, and the received ranging pulses do not overlap. The standard reflector 1 should satisfy that it can cover the entire field of view of the TOF sensor (receive and reflect the complete ranging pulses) so that the TOF sensor can receive the complete ranging pulses. In addition, ranging pulses can be emitted by the emitter of the TOF sensor, the ranging pulses emitted by the TOF sensor are reflected by the standard reflector 2 located at the L2 distance (the first calibration distance), and the ranging pulses are received by the receiver of the TOF sensor. Among them, the target reflectivity of the L2 calibration must satisfy that the ranging pulses reflected by the standard reflector 2 to the receiver do not overlap. In one embodiment, if there is partial overlap of the ranging pulses reflected to the receiver, the ranging pulses of the overlapping part can be estimated according to the previously obtained corresponding relationship of the acquisition element reference difference degree.

[0079] In an example, the acquisition element installed on the receiver of the TOF sensor can be a SPAD. The following takes the SPAD array as an example for illustration. In one embodiment, the TOF sensor can be fixed, and the standard card (standard reflector 1) made of a standard reflectivity material can be fixed at a distance L1 from the TOF sensor. At this time, it can be ensured that the plane of the standard card is perpendicular to the pulse emission path of the TOF sensor. The ranging function of the TOF sensor is started, and a set of crosstalk array data (SPAD difference degree corresponding relationship) is obtained through the ranging pulses collected by each SPAD in the SPAD array. The crosstalk array data is collected by using multiple TOF sensors, and the multiple crosstalk array data is averaged to obtain the crosstalk array shape (SPAD reference difference degree corresponding relationship) of the TOF sensor.

[0080] In another embodiment, each TOF sensor can be calibrated during the mass production of a mobile device. In one example, the TOF sensor can be fixed, and a standard card (standard reflector 2) made of a standard reflectivity material can be fixed at a distance L2 from the TOF sensor. The ranging function of the TOF sensor is activated, and the emitted ranging pulses are collected by the SPAD. The crosstalk amplitude collected by the TOF sensor (the intensity of the ranging pulses collected by each SPAD) is used to perform crosstalk calibration on any one SPAD in the SPAD array, and zero-offset calibration is performed using the time-of-flight data collected by any one SPAD. The crosstalk array shape of the SPAD (the corresponding relationship of the SPAD reference difference) is called to perform reference SPAD calibration on the differences between the SPADs in the array (that is, perform crosstalk calibration on all other SPADs except the calibrated SPAD). After the calibration is completed, the TOF sensor is used for ranging to determine the focusing accuracy of the calibrated TOF sensor. And after the calibration data meets the conditions required for focusing, the calibration data is saved to the storage chip.

[0081] In the TOF sensor calibration method provided by the embodiments of the present disclosure, when performing zero-offset calibration on the TOF sensor, the acquisition element array can be used as a whole for zero-offset calibration. In one example, the TOF sensor can be calibrated by using the time-of-flight data collected by the acquisition element.

[0082] In the embodiments of the present disclosure, multiple time-of-flight (TOF) sensors each having an acquisition element array can be controlled to measure the distance to a second calibration distance. During the distance measurement by the multiple TOF sensors, ranging pulses of each acquisition element in the acquisition element array of each TOF sensor can be acquired. Based on the ranging pulses of each acquisition element, a difference degree correspondence relationship of each acquisition element in the acquisition array can be determined, thereby obtaining a difference degree correspondence relationship of the acquisition elements of multiple TOF sensors. In one example, the difference degree correspondence relationship of the acquisition elements can be determined based on the intensity of the ranging pulses of the acquisition elements. After determining the difference degree correspondence relationship of the acquisition elements, normalization processing can be performed on the obtained difference degree correspondence relationship of the acquisition elements of multiple TOF sensors to obtain a reference difference degree correspondence relationship of the acquisition elements. The reference difference degree correspondence relationship of the acquisition elements can be used for crosstalk calibration of a TOF sensor having an acquisition element array. In one implementation, during the process of using a TOF sensor for distance measurement, an acquisition element in the acquisition element array is first selected as a reference acquisition element. Crosstalk calibration is performed on the reference acquisition element to obtain crosstalk calibration parameters of the reference acquisition element. Based on the crosstalk calibration parameters of the reference acquisition element and the pre-determined reference difference degree correspondence relationship of the acquisition elements, crosstalk calibration parameters of all other acquisition elements in the acquisition element array except the reference acquisition element are determined, thereby obtaining crosstalk calibration parameters of the acquisition element array. In addition, zero-offset calibration can be performed on the time-of-flight data acquired by any one acquisition element in the acquisition element array to obtain zero-offset calibration parameters. The TOF sensor is calibrated by using the obtained crosstalk calibration parameters and zero-offset calibration parameters. Through the present disclosure, calibration of a TOF sensor having a rectangular array of acquisition elements can be achieved.

[0083] Based on the same concept, embodiments of the present disclosure further provide a TOF sensor calibration device.

[0084] It can be understood that, in order to implement the above functions, the TOF sensor calibration device provided in the embodiments of the present disclosure includes corresponding hardware structures and / or software modules for executing each function. Combining the units and algorithm steps of each example disclosed in the embodiments of the present disclosure, the embodiments of the present disclosure can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the technical solution of the embodiments of the present disclosure.

[0085] Figure 9 is a block diagram of a TOF sensor calibration device shown according to an exemplary embodiment. Referring to Figure 9 , the device 100 includes a control unit 101 and a calibration unit 102.

[0086] A control unit 101 is configured to control the TOF sensor to measure the distance to a first calibration distance. A calibration unit 102 is configured to perform crosstalk calibration on each acquisition element in the acquisition element array respectively during the process of measuring the first calibration distance, to obtain the crosstalk calibration parameters of the acquisition element array, and to perform zero-offset calibration on the acquisition element array to obtain the zero-offset calibration parameters. Based on the crosstalk calibration parameters and the zero-offset calibration parameters, the TOF sensor is calibrated.

[0087] In one implementation, the calibration unit 102 performs crosstalk calibration on each acquisition element in the acquisition element array in the following manner: Any one acquisition element in the acquisition element array is used as a reference acquisition element, and crosstalk calibration is performed on the reference acquisition element to obtain the reference crosstalk calibration parameters. Based on the corresponding relationship of the acquisition element reference difference degrees, the difference degree corresponding relationship between the reference acquisition element and other acquisition elements in the acquisition element array is determined, and based on the difference degree corresponding relationship and the reference crosstalk calibration parameters, the crosstalk calibration parameters of each acquisition element in the other acquisition elements are determined respectively. The reference crosstalk calibration parameters and the crosstalk calibration parameters of each acquisition element in the other acquisition elements are used as the crosstalk calibration parameters of the acquisition element array.

[0088] In one implementation, the calibration unit 102 determines the corresponding relationship of the acquisition element reference difference degrees in the following manner: Control a plurality of TOF sensors having an acquisition element array to measure the distance to a second calibration distance. During the process of the plurality of TOF sensors measuring the second calibration distance, measure the ranging pulses of each acquisition element in the acquisition element array of each TOF sensor. For each TOF sensor among the plurality of TOF sensors, based on the difference degrees between the ranging pulses of each acquisition element respectively, determine the difference degree corresponding relationship of each acquisition element in the acquisition element array, and obtain the acquisition element difference degree corresponding relationships of the plurality of TOF sensors. Normalize the acquisition element difference degree corresponding relationships of the plurality of TOF sensors to obtain the corresponding relationship of the acquisition element reference difference degrees.

[0089] In one implementation, the second calibration distance is such that each acquisition element in the acquisition element arrays of the plurality of TOF sensors receives a ranging pulse, and the received ranging pulses do not overlap.

[0090] In one implementation, the calibration unit 102 determines the difference degree corresponding relationship of each acquisition element in the acquisition element array based on the difference degrees between the ranging pulses of each acquisition element in the following manner: Obtain the ranging pulse intensities of each acquisition element in the acquisition element array, and determine the proportional relationship between the ranging pulse intensities. Based on the proportional relationship between the ranging pulse intensities, determine the difference degree corresponding relationship of each acquisition element in the acquisition element array.

[0091] In one implementation, the calibration unit 102 calibrates the zero offset of the acquisition element array in the following manner to obtain zero offset calibration parameters: Obtain the time-of-flight data of any one acquisition element in the acquisition element array. Based on the time-of-flight data, perform zero offset calibration to obtain zero offset calibration parameters.

[0092] In one implementation, the calibration unit 102 controls the TOF sensor to measure the distance to the first calibration distance in the following manner: Fix a standard card with a standard reflectivity material at the first calibration distance position. Control the TOF sensor to emit a ranging pulse towards the standard card, and perform ranging based on the ranging pulse reflected from the standard card to the acquisition element array. Wherein, the standard reflectivity satisfies that the ranging pulses reflected from the standard card to the acquisition elements do not overlap.

[0093] Regarding the device in the above embodiments, the specific manners in which each module performs operations have been described in detail in the embodiments related to the method, and will not be elaborated herein.

[0094] Figure 10 FIG. is a block diagram of a device 200 for calibrating a time-of-flight sensor according to an exemplary embodiment. For example, the device 200 may be a mobile phone, a computer, a digital broadcast terminal, a messaging device, a game console, a tablet device, a medical device, a fitness device, a personal digital assistant, etc.

[0095] Referring to Figure 10 , the device 200 may include one or more of the following components: a processing component 202, a memory 204, a power component 206, a multimedia component 208, an audio component 210, an input / output (I / O) interface 212, a sensor component 214, and a communication component 216.

[0096] The processing component 202 generally controls the overall operation of the device 200, such as operations associated with display, telephone call, data communication, camera operation, and recording operation. The processing component 202 may include one or more processors 220 to execute instructions to complete all or part of the steps of the above method. In addition, the processing component 202 may include one or more modules to facilitate the interaction between the processing component 202 and other components. For example, the processing component 202 may include a multimedia module to facilitate the interaction between the multimedia component 208 and the processing component 202.

[0097] The memory 204 is configured to store various types of data to support the operation of the device 200. Examples of such data include instructions for any application or method operating on the device 200, contact data, phone book data, messages, pictures, videos, and the like. The memory 204 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk, or optical disk.

[0098] The power component 206 provides power for various components of the device 200. The power component 206 may include a power management system, one or more power sources, and other components associated with generating, managing, and distributing power for the device 200.

[0099] The multimedia component 208 includes a screen that provides an output interface between the device 200 and the user. In some embodiments, the screen may include a liquid crystal display (LCD) and a touch panel (TP). If the screen includes a touch panel, the screen can be implemented as a touch screen to receive input signals from the user. The touch panel includes one or more touch sensors to sense touches, swipes, and gestures on the touch panel. The touch sensors can not only sense the boundaries of touch or swipe actions, but also detect the duration and pressure associated with the touch or swipe operation. In some embodiments, the multimedia component 208 includes a front camera and / or a rear camera. When the device 200 is in an operating mode, such as a shooting mode or a video mode, the front camera and / or the rear camera can receive external multimedia data. Each of the front camera and the rear camera can be a fixed optical lens system or have a focal length and optical zoom capabilities.

[0100] The audio component 210 is configured to output and / or input audio signals. For example, the audio component 210 includes a microphone (MIC) that is configured to receive external audio signals when the device 200 is in an operating mode, such as a call mode, a recording mode, and a voice recognition mode. The received audio signals can be further stored in the memory 204 or transmitted via the communication component 216. In some embodiments, the audio component 210 further includes a speaker for outputting audio signals.

[0101] The I / O interface 212 provides an interface between the processing component 202 and a peripheral interface module, which can be a keyboard, a click wheel, buttons, etc. These buttons can include, but are not limited to: a home button, a volume button, a power-on button, and a lock button.

[0102] The sensor assembly 214 includes one or more sensors for providing a status assessment of various aspects of the device 200. For example, the sensor assembly 214 can detect the on / off state of the device 200, the relative positioning of components, such as the display and keypad of the device 200. The sensor assembly 214 can also detect a change in the position of the device 200 or a component of the device 200, the presence or absence of user contact with the device 200, the orientation or acceleration / deceleration of the device 200, and the temperature change of the device 200. The sensor assembly 214 can include a proximity sensor configured to detect the presence of nearby objects without any physical contact. The sensor assembly 214 can also include a light sensor, such as a CMOS or CCD image sensor, for use in imaging applications. In some embodiments, the sensor assembly 214 can also include an acceleration sensor, a gyroscope sensor, a magnetic sensor, a pressure sensor, or a temperature sensor.

[0103] The communication component 216 is configured to facilitate communication between the device 200 and other devices in a wired or wireless manner. The device 200 can access a wireless network based on communication standards, such as WiFi, 2G, or 3G, or a combination thereof. In an exemplary embodiment, the communication component 216 receives a broadcast signal or broadcast-related information from an external broadcast management system via a broadcast channel. In an exemplary embodiment, the communication component 216 further includes a near field communication (NFC) module to facilitate short-range communication. For example, the NFC module can be implemented based on radio frequency identification (RFID) technology, infrared data association (IrDA) technology, ultra-wideband (UWB) technology, Bluetooth (BT) technology, and other technologies.

[0104] In an exemplary embodiment, the device 200 can be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components for performing the above-described method.

[0105] In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions, such as the memory 204 including instructions, is also provided. The above instructions can be executed by the processor 220 of the device 200 to complete the above-described method. For example, the non-transitory computer-readable storage medium can be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device, etc.

[0106] It will be understood that in the present disclosure, "a plurality of" means two or more, and other quantifiers are similar thereto. "And / or" describes the associated relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. The singular forms of "a", "the", and "said" are also intended to include the plural forms unless the context clearly indicates otherwise.

[0107] It can be further understood that the terms "first", "second", etc. are used to describe various information, but such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other, and do not represent a specific order or degree of importance. In fact, the expressions such as "first" and "second" can be used interchangeably. For example, without departing from the scope of the present disclosure, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information.

[0108] It can be further understood that unless otherwise specified, "connection" includes direct connection without other components between the two, and also includes indirect connection with other elements between the two.

[0109] It can be further understood that although the operations are described in a specific order in the drawings in the embodiments of the present disclosure, it should not be understood that these operations are required to be performed in the specific order shown or in a serial order, or that all the operations shown are required to obtain the desired result. In a specific environment, multitasking and parallel processing may be advantageous.

[0110] Those skilled in the art will readily conceive of other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure, which follow the general principles of the present disclosure and include well-known common general knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the following claims.

[0111] It should be understood that the present disclosure is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present disclosure is only limited by the appended claims.

Claims

1. A calibration method for a time-of-flight sensor, characterized in that, an acquisition element array for acquiring ranging pulses is installed in a receiver of the time-of-flight sensor, and the calibration method for the time-of-flight sensor includes: controlling the time-of-flight sensor to measure the distance of a first calibration distance; during the process of measuring the first calibration distance, based on the corresponding relationship of the acquisition element reference difference degrees, respectively performing crosstalk calibration on each acquisition element in the acquisition element array to obtain the crosstalk calibration parameters of the acquisition element array, and performing zero-offset calibration on the acquisition element array to obtain zero-offset calibration parameters, wherein the corresponding relationship of the acquisition element reference difference degrees represents the difference degrees between the ranging pulses of each acquisition element in the acquisition element array; calibrating the time-of-flight sensor based on the crosstalk calibration parameters and the zero-offset calibration parameters.

2. The calibration method for a time-of-flight sensor according to claim 1, characterized in that, the step of respectively performing crosstalk calibration on each acquisition element in the acquisition element array includes: taking any one acquisition element in the acquisition element array as a reference acquisition element, and performing crosstalk calibration on the reference acquisition element to obtain reference crosstalk calibration parameters; based on the corresponding relationship of the acquisition element reference difference degrees, determining the difference degree corresponding relationship between the reference acquisition element and other acquisition elements in the acquisition element array, and respectively determining the crosstalk calibration parameters of each acquisition element in the other acquisition elements based on the difference degree corresponding relationship and the reference crosstalk calibration parameters; taking the reference crosstalk calibration parameters and the crosstalk calibration parameters of each acquisition element in the other acquisition elements as the crosstalk calibration parameters of the acquisition element array.

3. The calibration method for a time-of-flight sensor according to claim 2, characterized in that, the corresponding relationship of the acquisition element reference difference degrees is determined in the following manner: controlling a plurality of time-of-flight sensors having the acquisition element array to measure the distance of a second calibration distance; during the process of the plurality of time-of-flight sensors measuring the second calibration distance, acquiring the ranging pulses of each acquisition element in the acquisition element array of each time-of-flight sensor; for each time-of-flight sensor in the plurality of time-of-flight sensors, respectively determining the difference degree corresponding relationship of each acquisition element in the acquisition element array based on the difference degrees between the ranging pulses of the respective acquisition elements, to obtain the acquisition element difference degree corresponding relationships of the plurality of time-of-flight sensors; performing normalization processing on the acquisition element difference degree corresponding relationships of the plurality of time-of-flight sensors to obtain the corresponding relationship of the acquisition element reference difference degrees.

4. The calibration method for a time-of-flight sensor according to claim 3, characterized in that, the second calibration distance satisfies that each acquisition element in the acquisition element array of the plurality of time-of-flight sensors receives a ranging pulse, and the received ranging pulses do not overlap.

5. The calibration method for a time-of-flight sensor according to claim 3, characterized in that, Determining the difference degree correspondence relationship of each acquisition element in the acquisition element array based on the difference degree between the ranging pulses of each acquisition element includes: Obtaining the ranging pulse intensities of each acquisition element in the acquisition element array and determining the proportional relationship between the ranging pulse intensities; Based on the proportional relationship between the ranging pulse intensities, determining the difference degree correspondence relationship of each acquisition element in the acquisition element array.

6. The time-of-flight sensor calibration method according to claim 1, characterized in that Performing zero-offset calibration on the acquisition element array to obtain zero-offset calibration parameters, including: Obtaining the time-of-flight data of any one acquisition element in the acquisition element array; Performing zero-offset calibration based on the time-of-flight data to obtain zero-offset calibration parameters.

7. The time-of-flight sensor calibration method according to claim 1, characterized in that Controlling the time-of-flight sensor to measure the distance to a first calibration distance includes: Fixing a standard card with a standard reflectivity material at the first calibration distance position; Controlling the time-of-flight sensor to emit a ranging pulse to the standard card and performing ranging based on the ranging pulse reflected by the standard card to the acquisition element array; Wherein, the standard reflectivity is such that the ranging pulses reflected by the standard card to the acquisition elements do not overlap.

8. A time-of-flight sensor calibration device, characterized in that A single-photon avalanche diode acquisition element array is installed in the receiver of the time-of-flight sensor, and the time-of-flight sensor calibration device includes: A control unit for controlling the time-of-flight sensor to measure the distance to a first calibration distance; A calibration unit for, during the process of measuring the distance to the first calibration distance, respectively performing crosstalk calibration on each acquisition element in the acquisition element array based on the acquisition element reference difference degree correspondence relationship to obtain the crosstalk calibration parameters of the acquisition element array, and performing zero-offset calibration on the acquisition element array to obtain zero-offset calibration parameters, wherein the acquisition element reference difference degree correspondence relationship characterizes the difference degree between the ranging pulses of each acquisition element in the acquisition element array; Calibrating the time-of-flight sensor based on the crosstalk calibration parameters and the zero-offset calibration parameters.

9. The time-of-flight sensor calibration device according to claim 8, characterized in that The calibration unit performs crosstalk calibration on each acquisition element in the acquisition element array in the following manner: Taking any one acquisition element in the acquisition element array as a reference acquisition element and performing crosstalk calibration on the reference acquisition element to obtain reference crosstalk calibration parameters; Based on the acquisition element reference difference degree correspondence relationship, determining the difference degree correspondence relationship between the reference acquisition element and other acquisition elements in the acquisition element array, and based on the difference degree correspondence relationship and the reference crosstalk calibration parameters, respectively determining the crosstalk calibration parameters of each acquisition element in the other acquisition elements; Taking the reference crosstalk calibration parameters and the crosstalk calibration parameters of each acquisition element in the other acquisition elements as the crosstalk calibration parameters of the acquisition element array.

10. The time-of-flight sensor calibration device according to claim 9, wherein, the calibration unit determines the corresponding relationship of the reference difference degree of the acquisition elements in the following manner: Controlling a plurality of time-of-flight sensors having the acquisition element array to measure the distance to a second calibration distance; During the process of the plurality of time-of-flight sensors measuring the second calibration distance, collecting the ranging pulses of each acquisition element in the acquisition element array of each time-of-flight sensor; For each time-of-flight sensor among the plurality of time-of-flight sensors, respectively determining the corresponding relationship of the difference degree of each acquisition element in the acquisition element array based on the difference degree between the ranging pulses of the respective acquisition elements, and obtaining the corresponding relationship of the difference degree of the acquisition elements of the plurality of time-of-flight sensors; Normalizing the corresponding relationship of the difference degree of the acquisition elements of the plurality of time-of-flight sensors to obtain the corresponding relationship of the reference difference degree of the acquisition elements.

11. The time-of-flight sensor calibration device according to claim 10, wherein, the second calibration distance satisfies that each acquisition element in the acquisition element array of the plurality of time-of-flight sensors receives a ranging pulse, and the received ranging pulses do not overlap.

12. The time-of-flight sensor calibration device according to claim 10, wherein, the calibration unit determines the corresponding relationship of the difference degree of each acquisition element in the acquisition element array based on the difference degree between the ranging pulses of the respective acquisition elements in the following manner: Obtaining the ranging pulse intensity of each acquisition element in the acquisition element array and determining the proportional relationship between the ranging pulse intensities; Based on the proportional relationship between the ranging pulse intensities, determining the corresponding relationship of the difference degree of each acquisition element in the acquisition element array.

13. The time-of-flight sensor calibration device according to claim 8, wherein, the calibration unit calibrates the zero-point offset of the acquisition element array in the following manner to obtain zero-point offset calibration parameters: Obtaining the time-of-flight data of any one acquisition element in the acquisition element array; Based on the time-of-flight data, performing zero-point offset calibration to obtain zero-point offset calibration parameters.

14. The time-of-flight sensor calibration device according to claim 8, wherein, the calibration unit controls the time-of-flight sensor to measure the distance to a first calibration distance in the following manner: Fixing a standard card with a standard reflectivity material at the first calibration distance position; Controlling the time-of-flight sensor to emit a ranging pulse to the standard card and performing ranging based on the ranging pulse reflected by the standard card to the acquisition element array; wherein, the standard reflectivity satisfies that the ranging pulses reflected by the standard card to the acquisition elements do not overlap.

15. A time-of-flight sensor calibration device, wherein, comprising: a processor; a memory for storing instructions executable by the processor; wherein, the processor is configured to: execute the time-of-flight sensor calibration method according to any one of claims 1 to 7.

16. A storage medium, wherein, Instructions are stored in the storage medium, and when the instructions in the storage medium are executed by a processor, the processor is enabled to execute the time-of-flight sensor calibration method according to any one of claims 1 to 7.

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