Itof camera, calibration method and related devices

Abstract

This invention discloses an ITOF camera, a smart terminal, a calibration method, and a computer-readable storage medium. The ITOF camera includes a transmitter, a collector, a light guide structure connecting the transmitter and the collector, and a control and processor. The control and processor controls a first light source to emit a first light signal and controls a measurement photosensitive unit to collect the reflected first light signal for calculating the distance to a target object. The control and processor also controls a second light source to emit a second light signal to the light guide structure and controls a reference photosensitive unit to collect the second light signal transmitted through the light guide structure to calculate the corresponding first light transmission measurement distance. The error between the first light transmission measurement distance and the actual light transmission distance is calculated as a second global error, and the distance to the target object is corrected based on the second global error. Therefore, the ITOF camera in this invention can both perform distance measurement and calibrate the global error of the ITOF camera in real time.

Description

Technical Field

[0001] This invention relates to the field of camera technology, and more particularly to an ITOF camera, a smart terminal, a calibration method, and a computer-readable storage medium. Background Technology

[0002] Before leaving the factory, ITOF cameras require global offset calibration. This offset includes the electronic signal delay of the ITOF camera itself and the electronic signal delay of the printed circuit board (PCB). Different cameras and different PCBs have different signal delays, meaning different offsets, so each camera needs individual calibration. However, even successfully calibrated ITOF cameras experience changes in signal delay due to the aging of electronic components during long-term use, resulting in altered offsets. Currently, to ensure measurement accuracy, long-used ITOF cameras are typically returned to the factory for offset recalibration, increasing after-sales maintenance costs.

[0003] Therefore, existing technologies still need to be improved and developed to address the aforementioned shortcomings. Summary of the Invention

[0004] The main objective of this invention is to provide an ITOF camera, a smart terminal, a calibration method, and a computer-readable storage medium, aiming to solve the problem in the prior art that ITOF cameras need to be returned to the factory for offset recalibration after long-term use, which increases the cost of after-sales maintenance.

[0005] To achieve the above objectives, a first aspect of the present invention provides an ITOF camera, comprising a transmitter, a collector, a light guide structure connecting the transmitter and the collector, and a control and processor, wherein: the transmitter includes a first light source and a second light source; the collector includes a measurement photosensitive unit and a reference photosensitive unit; the control and processor is used to control the first light source to emit a first light signal to a target object, and to control the measurement photosensitive unit to collect the first light signal reflected by the target object and generate a first electrical signal, and to process the first electrical signal to calculate the distance to the target object; the control and processor is also used to control the second light source to emit a second light signal to the light guide structure, and to control the reference photosensitive unit to collect the second light signal transmitted through the light guide structure and generate a second electrical signal, and to process the second electrical signal to calculate the corresponding first light transmission measurement distance, and to calculate the error between the first light transmission measurement distance and the actual light transmission distance as a second global error; the control and processor is also used to correct the distance to the target object based on the second global error.

[0006] In some embodiments, the transmitter further includes: an optical diffuser, the optical diffuser comprising a microstructure region and a non-microstructure region, wherein the microstructure region is disposed in the transmission optical path of the first light source for modulating the beam emitted by the first light source to project a floodlight beam onto the target object; the non-microstructure region is disposed between the microstructure region and the light guide structure to prevent the beam emitted by the first light source from entering the light guide structure, the light guide structure being an optical fiber or a cavity with a mirrored inner wall.

[0007] A second aspect of the present invention provides a smart terminal, including a processor, a memory, and an ITOF camera as described above, wherein: the processor is used to send a calibration signal to the ITOF camera; the control and processor in the ITOF camera are used to control a second light source to emit a second light signal of a preset frequency, which is incident on a reference photosensitive unit through a light guide structure, and generate a third electrical signal; the control and processor are also used to calculate the corresponding second light transmission measurement distance based on the third electrical signal, calculate the distance error between the second light transmission measurement distance and the actual light transmission distance of the second light signal, calculate the signal delay of a pre-stored second global error and the distance error, and calculate a third global error based on the signal delay and the pre-stored first global error, so as to use the third global error to correct the distance of the target object measured by the ITOF camera.

[0008] A third aspect of the present invention provides a calibration method, comprising: controlling a second light source to emit a second light signal of a preset frequency, which is incident on a reference photosensitive unit through a light guide structure to generate a third electrical signal; calculating a corresponding second light transmission measurement distance based on the third electrical signal; calculating the distance error between the second light transmission measurement distance and the actual light transmission distance; calculating a pre-stored second global error and the distance error to perform a signal delay; and calculating a third global error based on the signal delay and the pre-stored first global error, so as to use the third global error to correct the distance of the target object measured by the ITOF camera.

[0009] A fourth aspect of the present invention provides a computer-readable storage medium storing a calibration program, which, when executed by a processor, implements the steps of the above-described calibration method.

[0010] In summary, in this embodiment, the controller and processor can control the first light source to emit a first light signal to the target object, which is then reflected by the target object to the measuring photosensitive unit for distance measurement. It can also control the second light source to emit a second light signal to the light guide structure, which is then incident on the reference photosensitive unit for second global error calculation. The distance to the target object is then corrected based on this second global error. Therefore, the ITOF camera in this invention can both perform distance measurement and calibrate the global error of the ITOF camera in real time, eliminating the need for terminal manufacturers to perform global error calibration on the production line. This solves the problem of products needing to be returned to the factory for offset recalibration after long-term use to ensure accuracy, thereby reducing after-sales maintenance costs. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art 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 effort.

[0012] Figure 1 This is a system block diagram of the smart terminal according to an embodiment of the present invention;

[0013] Figure 2 This is a system block diagram of an ITOF camera according to an embodiment of the present invention;

[0014] Figure 3 This is a flowchart illustrating the calibration method of an embodiment of the present invention;

[0015] Figure 4 This is a flowchart illustrating a calibration method according to another embodiment of the present invention;

[0016] Figure 5 This is a flowchart illustrating the calibration method of another embodiment of the present invention. Detailed Implementation

[0017] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0018] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0019] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0020] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0021] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrases "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and 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 effort are within the scope of protection of the present invention.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0024] Figure 1The diagram illustrates a system block diagram of a smart terminal, including a processor 20, a memory 30, and an ITOF camera 10 connected to it. As one of the mainstream 3D vision perception technologies, ITOF technology is widely used in smart terminal devices such as mobile phones, tablets, robotic vacuum cleaners, and mobile robots. For example, an ITOF camera can be installed in a robotic vacuum cleaner to collect 3D information about the robot's surrounding environment. This 3D information is then transmitted to the processor in the robotic vacuum cleaner. The processor performs obstacle scene recognition and localization based on the 3D information, and controls the robot to perform obstacle avoidance and path planning based on the processing results. The ITOF camera 10 includes a transmitter 100, a collector 200, and a controller and processor 300. The transmitter 100 emits modulated light signals toward multiple target points in the target scene. The collector 200 collects the light signals reflected by the targets and generates electrical signals. The controller and processor 300 is connected to the transmitter 100 and the collector 200 and controls their synchronous activation, processes the electrical signals output by the collector 200 to calculate the round-trip time of the light signal to the target point, and further calculates the distance to the target point. Those skilled in the art will understand that... Figure 1 The schematic diagram shown is only a partial structural diagram related to the present invention and does not constitute a limitation on the ITOF camera 10 to which the present invention is applied. Specifically, the ITOF camera 10 may include more or fewer components than shown in the figure, or combine some components, or have different component arrangements.

[0025] It should be noted that the control and processor 300 can be the processor 20 in the smart terminal, that is, the processor 20, together with the transmitter 100 and the collector 200, realizes the ranging and calibration functions. Alternatively, the control and processor 300 can also be a separate processor, which together with the transmitter 100 and the collector 200 constitutes the ITOF camera 10 of the present invention.

[0026] Currently, ITOF cameras require system error calibration before leaving the factory. The main calibration contents include temperature drift, depth error (FPPN), distance measurement error (wiggling), and global error (offset). The offset is primarily caused by the electronic signal delay of the ITOF camera itself and the electronic signal delay of the printed circuit board (PCB). Different cameras and different PCB test boards have different signal delays, i.e., different offsets, so each camera needs to be calibrated individually. However, even a successfully calibrated ITOF camera, when matched with different test boards, will introduce additional offset delays. For example, when assembling an ITOF camera into a smart terminal product, the entire device needs to be recalibrated and re-offset, and this calibration process is basically completed on the terminal manufacturer's production line. This increases the development cost for terminal manufacturers using ITOF cameras, reduces the user experience, and is detrimental to the widespread adoption of ITOF cameras. Moreover, even a successfully calibrated ITOF camera, during long-term use, will experience changes in signal delay due to the aging of electronic components, resulting in changes in offset, requiring recalibration. Currently, in order to ensure measurement accuracy, it is usually necessary to return long-term used ITOF cameras to the factory for offset recalibration, which increases the cost of after-sales maintenance.

[0027] To address the aforementioned issues, this application provides an ITOF camera with a calibration system and a calibration method for installing the ITOF camera in a smart terminal device. This method allows for real-time offset calibration of the ITOF camera without requiring terminal manufacturers to perform offset calibration on the production line. Furthermore, this ITOF system solves the problem of products needing to be returned to the factory for offset recalibration after long-term use to ensure accuracy, thereby reducing after-sales maintenance costs.

[0028] Figure 2This application illustrates an ITOF camera 10, which includes a transmitter 100, a collector 200, a controller and processor 300, and a light guide structure 400 connecting the transmitter 100 and the collector 200. The transmitter 100 includes a first light source 101 and a second light source 102. The collector 200 includes a reference photosensitive unit 201 and a measurement photosensitive unit 202. The controller and processor 300 is used to control the first light source 101 to emit a first light signal to the target object, and to control the measurement photosensitive unit 202 to collect the first light signal reflected by the target object and generate a first electrical signal, and to process the first electrical signal to calculate the distance of the target object. The controller and processor 300 is also used to control the second light source 102 to emit a second light signal to the light guide structure 400, and to control the reference photosensitive unit 201 to collect the second light signal transmitted through the light guide structure 400 and generate a second electrical signal, and to process the second electrical signal to calculate the first light transmission measurement distance of the second light signal, and to calculate the error between the first light transmission measurement distance and the actual light transmission distance as a second global error, and to correct the distance of the target object according to the second global error, thereby realizing the ranging function and offset calibration function of the ITOF camera 10.

[0029] In some embodiments, the first light source 101 and the second light source 102 can be light sources such as light-emitting diodes (LEDs), edge-emitting lasers (EELs), and vertical-cavity surface-emitting lasers (VCSELs), or they can be light source arrays composed of multiple light sources. The emitted light beams have the same modulation frequency and wavelength, and the emitted light beams can be visible light, infrared light, ultraviolet light, etc. In one embodiment, the first light source 101 is a light source array composed of multiple vertical-cavity surface-emitting lasers, used to emit a speckled pattern light beam toward the target object. The second light source 102 is a single-point light source, which can be any one of LEDs, EELs, and VCSELs. Preferably, the second light source 102 is a single-point VCSEL, used to emit a speckled light beam with a very small divergence angle incident on the light guide structure. In one embodiment, the emitter 100 includes a light source array composed of multiple light sources, and the light source array is configured to be partitioned and controlled to form the first light source 101 and the second light source 102. The number of light sources in the first light source 101 is greater than the number of light sources in the second light source 102, and the field of view of the light beam emitted by the first light source 101 is greater than the field of view of the light beam emitted by the second light source 102. It should be noted that the working modes of the first light source 101 and the second light source 102 can be adjusted according to the actual application, that is, the first light source 101 and the second light source 102 can work independently at different times, which is not limited here.

[0030] In some embodiments, such as Figure 2As shown, the emitter 100 also includes an optical diffuser 500, which comprises a microstructure region and a non-microstructure region. The microstructure region is disposed in the transmission optical path of the first light source 101 and is used to modulate the light beam emitted by the first light source 101 to project a floodlight beam onto the target object. The non-microstructure region is correspondingly disposed between the microstructure region and the light guide structure to prevent the light beam emitted by the first light source 101 from incident into the light guide structure. Specifically, the optical diffuser can be a diffuser or a soft-focus lens.

[0031] In some embodiments, the collector 200 includes an image sensor composed of multiple pixels, which may be an image sensor composed of a charge-coupled device (CCD), complementary metal-oxide-semiconductor (CMOS), avalanche diode (AD), single-photon avalanche diode (SPAD), etc., and the array size represents the resolution of the depth camera, such as 320x240. Generally, a readout circuit (not shown) composed of one or more of the following devices is also connected to the image sensor 121: a signal amplifier, a time-to-digital converter (TDC), an analog-to-digital converter (ADC), etc. Generally, the image sensor 121 includes at least one pixel, and each pixel includes multiple taps (used to store and read or discharge charge signals generated by incident photons under the control of corresponding electrodes), such as three taps, for reading charge signal data.

[0032] In one embodiment, the image sensor in the collector 200 is divided into two regions, including a measurement photosensitive unit 202 and a reference photosensitive unit 201. For example, a row, a column, or several pixels can be selected as the reference photosensitive unit 201, while the remaining pixels in the image sensor are the measurement photosensitive units 202. The reference photosensitive unit 201 corresponds to the light guide structure and is used to receive the second optical signal transmitted through the light guide structure to generate a second electrical signal for calibration. In some embodiments, the collector 200 further includes a receiving lens 600 and a filter 700. Preferably, the filter 700 is adapted to the measurement photosensitive unit 202. For example, the filter 700 can be attached to the surface of the measurement photosensitive unit 202. The light signal reflected back by the target object is incident on the measurement photosensitive unit 202 through the receiving lens 600 to generate a first electrical signal for ranging. The filter 700 needs to be a narrowband filter that matches the wavelength of the second light source to suppress ambient light in other bands and avoid interference from ambient light.

[0033] In some embodiments, the light guide structure 400 is an optical fiber or a cavity with a mirrored inner wall. Specifically, the light guide tube can be a single-mode optical fiber, a multimode optical fiber, or a mirror reflector.

[0034] In some embodiments, the controller and processor 300 may be a separate dedicated circuit, such as a dedicated SOC chip, FPGA chip, ASIC chip, etc., comprising a CPU, memory, bus, etc., or it may include general-purpose processing circuitry. For example, after the ITOF camera is integrated into a smart terminal, the processor in the smart terminal can serve as at least a part of the controller and processor 300. For ease of description, the two will be described separately below, but this does not limit the scope of protection of the present invention.

[0035] In one embodiment, the controller and processor 300 processes the first electrical signal to calculate the phase delay of the reflected first optical signal relative to the emitted first optical signal. Further based on phase delay Calculate the distance to the target ,Right now: , Let C be the modulation frequency of the first optical signal and C be the speed of light.

[0036] The ITOF camera provided in this application has its own calibration system, which requires offset calibration before leaving the factory. Specifically, a fixed distance is set between the camera and the ITOF camera. The calibration plate is controlled by the controller and processor 300. The first light source 101 emits a third light signal towards the calibration plate at a preset distance. The third light signal reflected by the calibration plate is incident on the measurement photosensitive unit 202 and generates a fourth electrical signal. The controller and processor 300 also processes the fourth electrical signal to calculate the distance to the calibration plate. The calculated distance The measurement distance of the calibration board is affected by the delay in electronic signal transmission. Distance from reality There is a deviation; the calculated error is: , This is the offset value that needs to be calibrated during regular offset calibration. This data is stored in the camera as the first global error. When actually measuring the target distance, this calibration offset value is used to correct the measured value of the target to obtain a more accurate measured distance value.

[0037] In some embodiments, the controller and processor 300 processes the second electrical signal to calculate the phase delay of the second optical signal received by the reference photosensitive unit 201 relative to the emitted second optical signal. Further based on phase delay Calculate the flight distance corresponding to the second light signal ,Right now: , The modulation frequency of the second optical signal.

[0038] Secondly, before leaving the factory, the controller and processor 300 controls the second light source 102 to emit a second light signal to the light guide structure 400. The second light signal transmitted through the light guide structure 400 is incident on the reference photosensitive unit 201 to generate a second electrical signal. The controller and processor 300 is also used to process the second electrical signal to calculate the corresponding first light transmission measurement distance. The measurement distance is affected by the delay in electronic signals. Actual distance of light transmission ( There is a deviation; the calculated error is: ,in, This indicates the distance from the second light source 102 to the light guide structure 400. Indicates the length of the light guide structure 400. This indicates the distance from the light guide structure 400 to the reference photosensitive unit 201; This refers to the offset value that needs to be calibrated during conventional offset calibration. This data is stored in the camera as a pre-stored second global error. When the ITOF camera actually measures the target distance, this calibrated offset value is used to correct the measured value of the target object, resulting in a more accurate measured distance value. It can be understood that when the ITOF camera measures distance, it can choose to use either the first or second global error to correct the distance value. Because a calibration system is built into the ITOF camera, the camera's offset can be calibrated in real time during application, or after a period of use, reducing new errors caused by the aging of electronic components. Furthermore, to address the different delays caused by different circuits in the terminal application, this application proposes a calibrated ITOF camera that also requires secondary calibration.

[0039] This application provides a smart terminal, including an ITOF camera 10, a processor 20, and a memory 30. After integrating the ITOF camera 10 into the smart terminal, the PCB board in the terminal device introduces additional optical signal delay errors, i.e., offset errors, requiring offset calibration of the entire device. However, since the ITOF camera 10 has a built-in calibration system, no additional calibration equipment or environment is needed; it can be completed using online software and algorithms. Specifically, in the terminal device, the processor 20 sends a calibration signal to the ITOF camera 10. The controller and processor 300 in the ITOF camera 10 control the second light source 102 to emit a second light signal of a preset frequency, which is incident on the reference photosensitive unit 201 through the light guide structure 400 to generate a third electrical signal. The corresponding second light transmission measurement distance is calculated based on the third electrical signal. The second light transmission measurement distance Actual distance of light transmission ( Perform distance error calculation: Furthermore, due to the additional signal delay caused by the electronic circuitry on the PCB board, the controller and processor 300 also uses the pre-stored second global error... With distance error Perform signal delay calculation: To calibrate the global error, the controller and processor 300 is also used to store the pre-stored first global error. With signal delay Perform global error calculation: This serves as the third global error and stores the final offset value. To calibrate the real-time global error, the third global error is stored in the camera. When actually measuring the target distance, this value is used to correct the measurement value to obtain a more accurate measured distance value for the target.

[0040] In summary, in this embodiment, the controller and processor 300 can control the first light source 101 to emit a first light signal to the target object, which is then reflected by the target object to the measuring photosensitive unit 202 for distance measurement. It can also control the second light source 102 to emit a second light signal to the light guide structure 400, which is then incident on the reference photosensitive unit 201 for global error calibration. Therefore, the ITOF camera in this invention can both perform distance measurement and calibrate the global error of the ITOF camera in real time, eliminating the need for terminal manufacturers to perform global error calibration on the production line. This solves the problem of products needing to be returned to the factory for offset calibration after long-term use to ensure accuracy, thereby reducing after-sales maintenance costs.

[0041] like Figure 3 As shown, the present invention also provides a calibration method for calibrating the global error of the ITOF camera 10 in the above embodiment after the ITOF camera is integrated into a smart terminal.

[0042] The calibration method is performed by the control and processor 300 in the ITOF camera, or by a smart terminal with an ITOF camera 10, and includes the following steps:

[0043] In step S301, the second light source 102 is controlled to emit a second light signal of a preset frequency, which is incident on the reference photosensitive unit 201 through the light guide structure 400 to generate a third electrical signal.

[0044] Step S302: Calculate the corresponding second optical transmission measurement distance based on the third electrical signal.

[0045] Step S303: Calculate the second optical transmission measurement distance. Actual distance of light transmission The distance error was calculated. Among them, the actual distance of optical transmission ,in, This indicates the distance from the second light source 102 to the light guide structure 400. Indicates the length of the light guide structure 400. This indicates the distance from the light guide structure 400 to the reference photosensitive unit 201.

[0046] Step S304: Calculate the pre-stored second global error. With distance error The signal delay meter calculates the .

[0047] Step S305, based on signal delay Compared with the pre-stored first global error Perform the third global error calculation to calculate This allows for the use of a third global error to correct the distance to the target object measured by the ITOF camera.

[0048] In some embodiments, the controller and processor 300, or a smart terminal with an ITOF camera 10, performs the following steps to obtain a pre-stored first global error, such as... Figure 4 As shown, it includes:

[0049] In step S401, the first light source 101 is controlled to emit a third light signal to the calibration plate at a preset measurement distance. The third light signal reflected by the calibration plate is incident on the measurement photosensitive unit 202 to generate a fourth electrical signal.

[0050] Step S402: Calculate the measurement distance of the calibration plate based on the fourth electrical signal; that is, control and processor 300 processes the fourth electrical signal to calculate the phase delay of the reflected third light signal relative to the emitted third light signal. Further based on phase delay Calculate the distance to the target ,Right now: , The modulation frequency of the third optical signal.

[0051] Step S403: Calculate the error between the preset distance and the measured distance of the calibration plate, and store it as the first global error in the pre-stored data. .

[0052] In some embodiments, the controller and processor 300, or a smart terminal with an ITOF camera 10, performs the following steps to obtain a pre-stored second global error, such as... Figure 5 As shown, it includes:

[0053] In step S501, the second light source 102 is controlled to emit a second light signal to the light guide structure 400, which then enters the reference photosensitive unit 201 through the light guide structure 400 to generate a second electrical signal.

[0054] Step S502: Calculate the corresponding first optical transmission measurement distance based on the second electrical signal, i.e., control and processor 300 processes the second electrical signal to calculate the phase delay of the second optical signal received by the reference photosensitive unit 201 relative to the emitted second optical signal. Further based on phase delay Calculate the flight distance corresponding to the second light signal ,Right now: , The modulation frequency of the second optical signal.

[0055] Step S503: Calculate the error between the first measured optical transmission distance and the actual optical transmission distance, and store it as a pre-stored second global error. Among them, the actual distance of optical transmission ( ),in, This indicates the distance from the second light source 102 to the light guide structure 400. Indicates the length of the light guide structure 400. This indicates the distance from the light guide structure 400 to the reference photosensitive unit 201.

[0056] In summary, in this calibration method, the second light source 102 is controlled to emit a second light signal of a preset frequency to the light guide structure 400, which then enters the reference photosensitive unit 201 through the light guide structure 400, generating a third electrical signal. The corresponding second light transmission measurement distance is calculated based on the third electrical signal, and the distance error is calculated between the second light transmission measurement distance and the actual light transmission distance. The pre-stored second global error and the distance error are used to calculate the signal delay. The signal delay and the pre-stored first global error are used to calculate the third global error, which is then used to correct the distance measured by the ITOF camera. Therefore, this calibration method allows for real-time calibration of the global error of the ITOF camera without requiring the terminal manufacturer to perform global error calibration on the production line. This solves the problem of needing to return the product to the factory for offset calibration after long-term use to ensure accuracy, thereby reducing after-sales maintenance costs.

[0057] Based on the above embodiments, the memory 30 of the smart terminal stores a calibration program that can run on the processor 20. When the calibration program is executed by the processor 20, it implements the steps of the above calibration method.

[0058] In some embodiments, when the calibration program is executed by the processor 20, the following operation instructions are performed: controlling the second light source 102 to emit a second light signal that passes through the light guide structure 400 and is incident on the reference photosensitive unit 201 to generate a second electrical signal; processing the second electrical signal to calculate the corresponding second light transmission measurement distance; calculating the distance error between the second light transmission measurement distance and the actual light transmission distance; calculating the signal delay of the pre-stored second global error and the distance error; and calculating a third global error based on the signal delay and the pre-stored first global error, so as to use the third global error to correct the distance measured by the ITOF camera.

[0059] This invention also provides a computer-readable storage medium storing a calibration program, which, when executed by a processor, implements the steps of the calibration method described above.

[0060] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0061] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the above device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this invention. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0062] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0063] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software 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 implementations should not be considered beyond the scope of this invention.

[0064] In the embodiments provided by this invention, it should be understood that the disclosed apparatus / terminal devices and methods can be implemented in other ways. For example, the apparatus / terminal device embodiments described above are merely illustrative. For instance, the division of the above modules or units is merely a logical functional division, and in actual implementation, it can be divided in other ways. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0065] If the integrated modules / units described above are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction.

[0066] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not mean that the essence of the corresponding technical solutions deviates from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. An ITOF camera characterized by, The ITOF camera comprises a transmitter, a collector, a light guide structure connecting the transmitter and the collector, and a control and processor, wherein The transmitter comprises a first light source and a second light source; The collector comprises a measurement photosensitive unit and a reference photosensitive unit; The control and processor is configured to control the first light source to emit a first light signal to a target object, control the measurement photosensitive unit to collect the first light signal reflected by the target object and generate a first electric signal, and process the first electric signal to calculate the distance of the target object; The control and processor is further configured to control the second light source to emit a second light signal to the light guide structure, control the reference photosensitive unit to collect the second light signal transmitted by the light guide structure and generate a second electric signal, and process the second electric signal to calculate a corresponding first light transmission measurement distance and an error between the first light transmission measurement distance and an actual light transmission distance as a second global error; The control and processor is further configured to correct the distance of the target object according to the second global error.

2. The ITOF camera of claim 1, wherein, The transmitter further comprises an optical diffuser, the optical diffuser comprises a microstructure region and a non-microstructure region, wherein the microstructure region is arranged on the transmission light path of the first light source and is configured to modulate the light beam emitted by the first light source to project a floodlight beam to the target object; and the non-microstructure region is arranged between the microstructure region and the light guide structure to avoid the light beam emitted by the first light source from being incident into the light guide structure.

3. The ITOF camera of claim 1, wherein, The light guide structure is an optical fiber or a cavity with a boundary surface.

4. The ITOF camera of claim 1, wherein, The control and processor is further configured to process the first electric signal to calculate the phase delay of the reflected first light signal relative to the emitted first light signal; and the control and processor is further configured to calculate the distance of the target object according to the phase delay.

5. The ITOF camera of claim 1, wherein, The control and processor is further configured to control the first light source to emit a third light signal to a calibration board at a preset distance, control the measurement photosensitive unit to generate a fourth electric signal by being incident to the measurement photosensitive unit with the third light signal reflected by the calibration board, process the fourth electric signal to calculate the measurement distance of the calibration board, and calculate the error between the preset distance and the measurement distance of the calibration board as a first global error.

6. A smart terminal, characterized by The ITOF camera comprises a processor, a memory, and an ITOF camera as claimed in claim 5, wherein The processor is configured to start a calibration signal to the ITOF camera; The control and processor is configured to control the second light source to emit a second light signal at a preset frequency through the light guide structure to be incident to the reference photosensitive unit and generate a third electric signal; The control and processor is further configured to calculate a corresponding second light transmission measurement distance according to the third electric signal, calculate the distance error between the second light transmission measurement distance and the actual light transmission distance, calculate the signal delay between the pre-stored second global error and the distance error, and perform third global error calculation according to the signal delay and the pre-stored first global error, so as to correct the distance of the target object measured by the ITOF camera by using the third global error; The formula for calculating the signal delay of the pre-stored second global error and the distance error is: ; is the signal delay; is the distance error; is the pre-stored second global error.

7. A method for calibrating an ITOF camera, applied to the intelligent terminal of claim 6, characterized in that, The calibration method comprises: controlling the second light source to emit a second light signal of a preset frequency to the light guide structure to be incident on the reference photosensitive unit, and generating a third electric signal; calculating a corresponding second light transmission measurement distance according to the third electric signal; calculating a distance error between the second light transmission measurement distance and an actual light transmission distance; calculating a signal delay of the distance error and a pre-stored second global error; performing third global error calculation according to the signal delay and the pre-stored first global error, and correcting a distance of a target object measured by the ITOF camera by using the third global error; The formula for calculating the signal delay of the pre-stored second global error and the distance error is: ; is the signal delay; is the distance error; is the pre-stored second global error.

8. The calibration method of claim 7, wherein, the calibration method further comprises: controlling the first light source to emit a third light signal to a calibration board at a preset distance, and generating a fourth electric signal by the third light signal reflected by the calibration board and incident on the measurement photosensitive unit; calculating a measurement distance of the calibration board according to the fourth electric signal; calculating an error between the preset distance and the measurement distance of the calibration board as a pre-stored first global error.

9. The calibration method of claim 7, wherein, the calibration method further comprises: controlling the second light source to emit a second light signal to the light guide structure to be incident on the reference photosensitive unit and generating a second electric signal; calculating a corresponding first light transmission measurement distance according to the second electric signal; calculating an error between the first light transmission measurement distance and an actual light transmission distance as a pre-stored second global error.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a calibration program, and the calibration program is executed by the processor to implement the steps of the calibration method according to any one of claims 7-9.

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