A test system and test method for a voice coil motor in a camera module

Abstract

The application discloses a kind of camera module in voice coil motor's test system and test method. Host computer will drive the driving instruction of the voice coil motor to be tested to be tested voice coil motor by product driving board transmission;Signal adapter plate will be tested voice coil motor required power signal and the driving signal generated by product driving board are adapted to be tested voice coil motor;Multi-axis laser range finder determines the position of the voice coil motor to be tested in multi-axis coordinate system when the voice coil motor to be tested moves and generates position information;Second MCU on analog signal acquisition board transforms position information and feeds back the transformed position information to host computer, and host computer obtains driving current value and the transformed position information corresponding to driving current value;The counter in second MCU controls the delay time between the start of motion of the mover in the voice coil motor to be tested and the start of position information collection of analog signal acquisition board. The application more accurately tests the voice coil motor to be tested.

Description

Technical Field

[0001] This invention relates to the field of testing technology for voice coil motors in camera modules, and specifically to a testing system and method for voice coil motors in camera modules. Background Technology

[0002] In camera modules, the voice coil motor (VCM) is a precision linear actuator. Its performance testing primarily focuses on electrical parameters, mechanical displacement, dynamic response, and environmental adaptability. Current mainstream testing techniques include open-loop current-displacement methods, closed-loop feedback methods, and dynamic performance testing. However, these techniques often overlook drawbacks such as hysteresis, nonlinear restoring force of springs, temperature drift, or the high cost of the testing systems, hindering widespread adoption. Furthermore, they face significant challenges in VCM testing, including the trade-off between accuracy and testing efficiency, and interference from multi-physics coupling factors. Summary of the Invention

[0003] In view of this, the present invention provides a testing system and method for the voice coil motor in a camera module, which can solve the above-mentioned technical problems.

[0004] To solve the above-mentioned technical problems, the present invention is implemented as follows.

[0005] A testing system for the voice coil motor in a camera module, comprising:

[0006] Non-magnetic stage, multi-axis laser rangefinder, power board, signal adapter board, rangefinder signal output unit, analog signal acquisition board, product driver board and host computer;

[0007] The host computer transmits the drive command to the voice coil motor under test (VCT) via the product driver board to drive the VCT motor to move along a preset motion trajectory within the linear motion area of ​​the VCT motor. The signal adapter board transfers the power signal required by the VCT motor and the drive signal generated by the product driver board to the VCT motor, and the mover of the VCT motor moves along the preset motion trajectory. The multi-axis laser rangefinder determines the position of the VCT motor in the multi-axis coordinate system and generates position information when the VCT motor moves. The second MCU on the analog signal acquisition board transforms the position information and feeds back the transformed position information to the host computer. The host computer obtains the drive current value and the transformed position information corresponding to the drive current value.

[0008] The first MCU deployed on the product driver board obtains the temperature output by the internal temperature sensor of the voice coil motor under test based on the signal adapter board. When the temperature exceeds the preset threshold, the host computer issues an interruption command for the test. The counter in the second MCU controls the delay time between the start of movement of the mover in the voice coil motor under test and the start of position information acquisition by the analog signal acquisition board.

[0009] Preferably, before testing the to-be-tested voice coil motor, the following operations are repeatedly performed several times:

[0010] A step-by-step driving signal from a negative limit to a positive limit is applied to the to-be-tested voice coil motor, so that the to-be-tested voice coil motor moves from the negative limit to the positive limit, and a movement trajectory of the to-be-tested voice coil motor is recorded.

[0011] According to the collected multiple movement trajectories, a linear motion region of the to-be-tested voice coil motor is determined.

[0012] Preferably, the kernel counter in the second MCU acquires the count of the kernel clock, and the delay time between the start of the movement of the to-be-tested voice coil motor driven by the driving signal and the start of the collection of the position information by the analog signal collection board is controlled by the change amount of the kernel clock.

[0013] Preferably, the multi-axis laser range finder receives reflected light of a reflector embedded on the to-be-tested voice coil motor, and the reflected light converges to form a light spot in the receiving area of the multi-axis laser range finder; when the to-be-tested voice coil motor moves, the position of the to-be-tested voice coil motor in the multi-axis coordinate system is determined based on the position and size of the light spot, a multi-axis linear analog signal is generated, and the second MCU on the analog signal collection board converts the position information based on the received multi-axis linear analog signal and feeds back the converted position information to the upper computer.

[0014] Preferably, after the test is completed, the upper computer sends a data return instruction to the analog signal collection board, and the analog signal collection board returns all the collected data to the upper computer.

[0015] A testing method for a voice coil motor in a camera module, based on the testing system as described above, the testing method comprising:

[0016] The upper computer sends a coil driving current instruction to the product driving board through a high-speed network port, the product driving board writes the coil driving current instruction into a specified register of the to-be-tested voice coil motor, the to-be-tested voice coil motor generates a constant current, the current flows through the coil of the to-be-tested voice coil motor, the product driving board acquires the voltage value across the coil of the to-be-tested voice coil motor and the current value flowing through the to-be-tested voice coil motor, and then transmits the voltage value and the current value to the upper computer through the high-speed network port, and the upper computer calculates the direct current resistance of the coil of the to-be-tested voice coil motor according to Ohm's law, and archives the direct current resistance.

[0017] A testing method for a voice coil motor in a camera module, based on the testing system as described above, the testing method comprising:

[0018] The host computer preloads a plurality of drive currents for driving the to-be-tested voice coil motor in batches to a product drive board, wherein each drive current has a current value, the current values of different drive currents are different, and one drive current is loaded each time; the product drive board sends the drive currents to the to-be-tested voice coil motor in a serial manner through a fixed frequency, and after sending each drive current, triggers an analog signal acquisition board to obtain the displacement of the to-be-tested voice coil motor in a plurality of axial directions calculated by a multi-axis laser range finder;

[0019] obtain the displacement corresponding to each drive current;

[0020] obtain the current value corresponding to each drive current and the displacement corresponding to the drive current, construct a two-dimensional matrix of the current value corresponding to the drive current and the displacement corresponding to the drive current, discretely differentiate the displacement in the two-dimensional matrix, and obtain the sensitivity value of each discrete point corresponding to each drive current; for each drive current, connect the sensitivity values of the discrete points corresponding to the drive current to form a sensitivity curve corresponding to the drive current; select a plurality of sampling points from the sensitivity curves corresponding to the drive currents to obtain a test result of the stroke test of the to-be-tested voice coil motor.

[0021] A test method of a voice coil motor in a camera module, based on the test system as described above, the test method comprising:

[0022] obtain the initial state of the internal moving components of the to-be-tested voice coil motor, the moving components including a ball and a spring;

[0023] perform a plurality of motion tests on the to-be-tested voice coil motor, each motion test comprising:

[0024] The host computer generates parameters for setting the drive current of the to-be-tested voice coil motor for a cycle test, and sends the parameters to the product drive board. The product drive board generates an IIC communication protocol instruction based on the parameters, sends the IIC communication protocol instruction to the to-be-tested voice coil motor through the signal adapter, drives the to-be-tested voice coil motor to move, and the product drive board reads the position information of the position sensor inside the to-be-tested voice coil motor, thereby determining the stroke of the to-be-tested voice coil motor;

[0025] upload the stroke of the to-be-tested voice coil motor to the host computer, and the host computer determines the maximum stroke and motion smoothness of the to-be-tested voice coil motor;

[0026] obtain the state of the internal moving components of the to-be-tested voice coil motor after the test, and estimate the service life of the to-be-tested voice coil motor based on the test result of the motion test and in combination with automatic optical inspection.

[0027] A test method of a voice coil motor in a camera module, based on the test system as described above, the test method comprising:

[0028] The upper computer outputs a plurality of discrete, fixed-time and fixed-step incremental square wave current digital step signals, and each square wave current digital step signal is:

[0029] The product drive board drives the to-be-tested voice coil motor based on a predetermined time interval specified by the step current instruction, and determines a step response time of the to-be-tested voice coil motor from a driving position to a target position.

[0030] The upper computer determines a maximum displacement amount and a displacement amount difference of each step point based on the light spot.

[0031] The step response of the to-be-tested voice coil motor corresponding to the square wave current digital step signal is determined based on the step response time, the maximum displacement amount and the displacement amount difference of each step point.

[0032] A testing method of a voice coil motor in a camera module is based on the testing system as described above, and the testing method comprises the following steps:

[0033] A plurality of discrete driving currents with equal current values are set.

[0034] For each discrete driving current:

[0035] The upper computer outputs the discrete driving current to the product drive board, and the product drive board drives the to-be-tested voice coil motor based on the discrete driving current; after the discrete driving current is completed, the corresponding position of the to-be-tested voice coil motor is determined based on the light spot.

[0036] The upper computer determines a position peak value and a mean square error corresponding to all positions based on the corresponding positions of the to-be-tested voice coil motor, and determines the stability of the testing system based on the position peak value and the mean square error.

[0037] A computer readable storage medium is provided, and a plurality of instructions are stored in the storage medium; the plurality of instructions are used for loading and executing the method as described above by a processor.

[0038] An electronic device is provided, and the electronic device comprises:

[0039] A processor is used for executing a plurality of instructions.

[0040] A memory is used for storing a plurality of instructions.

[0041] The plurality of instructions are stored in the memory and loaded and executed by the processor.

[0042] Advantages:

[0043] (1) The analog signal acquisition board and the product driving board have high-precision controllable signal delay, and the delay between driving triggering and acquisition can be controlled within 1us. Under the driving trajectory of rapid change, the motion trajectory of the measured object can be captured more accurately, and the real motion state of the measured voice coil motor can be more accurately reflected.

[0044] (2) The present application uses only two MCUs as the main control unit to complete complex process control and large data transmission, and the hardware cost is low. The first MCU is mainly used for data transmission between the upper computer and the measured object; the second MCU is mainly used for multi-axis position transformation information, and transmits the data to the upper computer.

[0045] (3) The present application uses mainstream MCU as the main control unit, the development data is more perfect, the development cycle is short, and the requirement for the developer is relatively low, which can reduce the development time and labor cost.

[0046] (4) The present application can complete non-standard customization through embedded programming, has strong flexibility, and can quickly develop and verify for customer verification. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 The present application is a test system structure diagram of a voice coil motor in a camera module. DETAILED DESCRIPTION

[0048] The present application will be described in detail below in combination with the drawings and examples.

[0049] As shown in Figure 1 , the present application proposes a test system of a voice coil motor in a camera module, which comprises:

[0050] a non-magnetic platform, a multi-axis laser range finder, a power board, a signal adapter board, a range finder signal output unit, an analog signal acquisition board, a product driving board and an upper computer;

[0051] The upper computer transmits the driving instruction of driving the measured voice coil motor to move along the preset motion trajectory in the motion linear region of the measured voice coil motor to the measured voice coil motor through the product driving board; the signal adapter board transmits the power supply signal required by the measured voice coil motor and the driving signal generated by the product driving board to the measured voice coil motor, and the rotor of the measured voice coil motor moves along the preset motion trajectory; the multi-axis laser range finder determines the position of the measured voice coil motor in the multi-axis coordinate system when the measured voice coil motor moves and generates position information; the second MCU on the analog signal acquisition board transforms the position information and feeds back the transformed position information to the upper computer, and the upper computer obtains the driving current value and the corresponding transformed position information of the driving current value;

[0052] The first MCU disposed on the product driving board acquires the temperature output by the internal temperature sensor of the voice coil motor to be tested based on the signal adapter board, and the host computer sends an interrupt test instruction when the temperature exceeds a preset threshold value; the counter in the second MCU controls the delay time between the start of movement of the moving element in the voice coil motor to be tested and the start of position information acquisition by the analog signal acquisition board.

[0053] Further, after the test is completed, the host computer sends a data return instruction to the analog signal acquisition board, and the analog signal acquisition board returns all the acquired data to the host computer.

[0054] Before testing the voice coil motor to be tested, the following operations are repeatedly performed several times to overcome the problem of ignoring the nonlinear restoring force of the spring piece in the traditional method:

[0055] A step-by-step driving signal from the negative limit to the positive limit is applied to the voice coil motor to be tested, so that the voice coil motor to be tested moves from the negative limit to the positive limit, and the movement trajectory of the voice coil motor to be tested is recorded.

[0056] According to the plurality of movement trajectories acquired, the linear region of the voice coil motor to be tested is determined, so that the voice coil motor to be tested works in the linear region in actual use, and the nonlinear spring rebound force region of the spring piece is avoided.

[0057] The material of the object in the space within the radius of 30 CM around the non-magnetic platform is copper. Since copper has no magnetism and poor magnetic conductivity, the material of the platform and the mechanism around the platform is made of copper, so that the magnetic flux in the space within the radius of 30 CM around the platform can be strictly controlled, thereby reducing the influence of the external magnetic field on the voice coil motor to be tested and reducing the magnetic hysteresis.

[0058] Further, the kernel counter in the second MCU acquires the count of the kernel clock, and the delay time between the start of movement of the moving element in the voice coil motor to be tested driven by the driving signal and the start of position information acquisition by the analog signal acquisition board is controlled by the change amount of the kernel clock. The delay time is equal to the change amount of the kernel clock multiplied by the count period.

[0059] In the present application, the first MCU and the second MCU complete the triggering and receiving of signals through the high-speed synchronous module integrated on the circuit board, and the kernel counter CNT on the MCU of the analog signal acquisition board is used to control the precise delay time, so that the delay time between triggering and acquisition can be strictly controlled within 1us.

[0060] The multi-axis laser range finder receives reflected light rays of a mirror embedded on a rotor of the voice coil motor to be tested, and the reflected light rays converge to form a light spot in a receiving area of the multi-axis laser range finder; when the voice coil motor to be tested moves, the position of the voice coil motor to be tested in a multi-axis coordinate system is determined based on the position and size of the light spot, a multi-axis linear analog signal is generated, and a second MCU on the analog signal acquisition board converts the received multi-axis linear analog signal to position information and feeds back the converted position information to the host computer.

[0061] The application monitors the temperature of the voice coil motor to be tested at all times during the entire test process, strictly monitors the temperature change during the test of the voice coil motor to be tested, and interrupts the test if the temperature exceeds a reasonable range.

[0062] The host computer generates a batch of discrete driving information based on a preset motion trajectory to form a driving instruction set.

[0063] The host computer sends the driving instruction set to the product driving board at one time, and the product driving board temporarily stores the driving instruction set in the memory, and then sends each driving instruction to the voice coil motor to be tested at a certain driving frequency through the timer in the MCU on the product driving board to make the rotor of the voice coil motor to be tested move. After each driving instruction is sent to the voice coil motor to be tested, the product driving board triggers the analog signal acquisition board through the high-speed synchronization module for acquisition, and the product driving board and the analog signal acquisition board communicate with each other through a private handshake protocol. The power board provides multiple working power required by the voice coil motor to be tested through the signal adapter board.

[0064] In the application, the test system includes a multi-axis laser range finder with high resolution (16.67mv / um) and high precision, which can simultaneously obtain micron-level motion of the object to be tested in X / Y / Z / Tx / Ty five axes; in addition, the test system is equipped with a multi-channel synchronous acquisition board with a sampling rate of 1MSPS and high resolution (20bit) and a high-speed (1MHz) IIC bus communication driving board, which enables the entire system to quickly respond and quickly capture the response. In order to facilitate various complex calculations on a large amount of raw data, the analog signal acquisition board and the product driving board of the test system are both equipped with a 100M Ethernet port for communication with the host computer, which greatly speeds up the data interaction between the host computer test software and the test board.

[0065] In addition, the test system has high synchronization characteristics in addition to fast closed-loop driving and acquisition. In order to keep the forward driving and the response acquisition of the object to be tested highly synchronized, the test system adds a high-speed synchronization module, and a private handshake protocol is added between the product driving board and the acquisition board, so that the time difference between triggering and acquisition is controlled within 1 microsecond. In order to prevent false triggering caused by interference in the industrial control environment, a precise delay software is added to the CNT counter in the MCU kernel during design to ensure the stability of the system.

[0066] The test items of the VCM (voice coil motor) need to cover its electrical characteristics, mechanical performance, dynamic response, function verification, etc.

[0067] Further, the application provides a test method for a voice coil motor in a camera module, based on the test system as described above, the test method comprising:

[0068] The host computer sends a coil driving current instruction to the product driving board through a high-speed network interface, the product driving board writes the coil driving current instruction into a specified register of the voice coil motor to be tested, the voice coil motor to be tested generates a constant current, the current flows through the coil of the voice coil motor to be tested, the product driving board acquires the voltage value across the coil of the voice coil motor to be tested and the current value flowing through the voice coil motor to be tested, and then transmits the voltage value and the current value to the host computer through the high-speed network interface, and the host computer calculates the direct current resistance of the coil of the voice coil motor to be tested according to Ohm's law and archives the direct current resistance.

[0069] The method completes the test of the electrical characteristics of the voice coil motor in the camera module.

[0070] The application provides a test method for a voice coil motor in a camera module, based on the test system as described above, the test method comprising:

[0071] The host computer preloads a plurality of driving currents for driving the voice coil motor to be tested to the product driving board in batches, wherein each driving current has a current value, the current values of different driving currents are different, and one driving current is loaded each time; the product driving board sends the driving currents to the voice coil motor to be tested in a serial manner through a fixed frequency, and after each driving current is sent, triggers the analog signal acquisition board to acquire the displacement of the voice coil motor to be tested in a plurality of axial directions calculated by the multi-axis laser range finder;

[0072] The displacement corresponding to each driving current is acquired.

[0073] The current value corresponding to each driving current and the displacement corresponding to the driving current are acquired, a two-dimensional matrix of the current value corresponding to the driving current and the displacement corresponding to the driving current is constructed, the displacement in the two-dimensional matrix is discretely differentiated to obtain the sensitivity value of each discrete point corresponding to each driving current, the sensitivity values of each discrete point corresponding to each driving current are connected to form a sensitivity curve corresponding to the driving current, a plurality of sampling points are selected from the sensitivity curves corresponding to the driving currents to obtain the test result of the stroke test of the voice coil motor to be tested.

[0074] In the application, since the two ends of the to-be-tested voice coil motor are in the non-linear region of the elastic sheet, and the position amount of the to-be-tested voice coil motor changes little when the driving current is increased, the sensitivity curve is in the shape of a Chinese character 'ji'. The relatively flat part of the upper part of the Chinese character 'ji' is the linear part of the to-be-tested voice coil motor, and the difference in the position amount corresponding to the linear part is taken as the maximum displacement amount of the to-be-tested voice coil motor. The specific calculation method is to take the sensitivity value at 0 mA driving current as A, find the first point at which the sensitivity is greater than 0.7*A in the data of the driving current less than 0 mA, mark the displacement value of the point as B1, find the last point at which the sensitivity is greater than A / 2 in the data of the driving current greater than 0 mA, mark the displacement value of the point as B2, and take the difference between B2 and B1 as the test result of the stroke test. In the application, the driving current of the voice coil motor is a symmetrical bipolar current when the driving current is 0 mA. The moving part of the voice coil motor is generally located at the center position of the to-be-tested voice coil motor when the moving part is stationary, and the bipolar current corresponds to the movement of the voice coil motor in opposite directions along a single axis.

[0075] The method completes the stroke test in the mechanical performance of the voice coil motor in the camera module.

[0076] The application provides a test method for a voice coil motor in a camera module, based on the test system as described above, and the test method comprises the following steps.

[0077] An initial state of an internal moving part of the to-be-tested voice coil motor is obtained, and the moving part comprises a ball and an elastic sheet.

[0078] Multiple motion tests are performed on the to-be-tested voice coil motor, and each motion test comprises the following steps.

[0079] The host computer generates a parameter for setting the driving current of the to-be-tested voice coil motor for cyclic testing, and sends the parameter to the product driving board, the product driving board generates an IIC communication protocol instruction based on the parameter, sends the IIC communication protocol instruction to the to-be-tested voice coil motor through the signal adapter, drives the to-be-tested voice coil motor to move, and the product driving board reads the position information of the position sensor inside the to-be-tested voice coil motor, so as to determine the stroke of the to-be-tested voice coil motor.

[0080] The stroke of the to-be-tested voice coil motor is uploaded to the host computer, and the host computer determines the maximum stroke and the smoothness of the to-be-tested voice coil motor.

[0081] An initial state of an internal moving part of the to-be-tested voice coil motor is obtained, and the moving part comprises a ball and an elastic sheet.

[0082] The method completes the mechanical durability test in the mechanical performance of the voice coil motor in the camera module.

[0083] The application provides a test method for a voice coil motor in a camera module, based on the test system as described above, and the test method comprises the following steps.

[0084] The host computer outputs a plurality of discrete, fixed-time, fixed-step incremental square wave current digital step signals, and for each square wave current digital step signal:

[0085] The product drive board drives the to-be-tested voice coil motor based on the predetermined time interval specified by the step current instruction, and determines the step response time of the to-be-tested voice coil motor from the driving position to the target position.

[0086] Based on the light spot, the host computer determines the maximum displacement and displacement difference of each step point.

[0087] Based on the step response time, the maximum displacement and displacement difference of each step point, the step response of the to-be-tested voice coil motor corresponding to the square wave current digital step signal is determined.

[0088] The method completes the step response test in the dynamic response of the voice coil motor in the camera module.

[0089] The present application provides a test method for a voice coil motor in a camera module, based on the test system as described above, the test method comprising:

[0090] The driving current signal is set, which has 2n driving current points, the first n driving current points correspond to 0mA, and the last n driving current points correspond to 20mA;

[0091] The host computer outputs the driving current signal set to the product drive board, and the product drive board drives the to-be-tested voice coil motor based on each driving current signal point, determines the corresponding position of the to-be-tested voice coil motor at each driving point based on the light spot, and determines the corresponding frequency of each driving point through calculation; the positions corresponding to each driving point form a position set.

[0092] The host computer performs discrete Fourier transform on the position set to obtain an amplitude-frequency characteristic value set, each element in the amplitude-frequency characteristic value set corresponding to each element in the position set; the direct current component is removed from the amplitude-frequency characteristic value set, and then the maximum value is determined from the remaining elements, and the frequency corresponding to the maximum value is the resonance frequency of the to-be-tested voice coil motor.

[0093] In the present application, all position information is transmitted to the host computer for algorithm calculation. Since the excitation current in the first half of the excitation signal remains unchanged, the measured voice coil motor will remain relatively prohibited; when the driving current occurs step mutation, the measured voice coil motor also moves. The moving part of the measured voice coil motor carries a mirror that oscillates under the interaction of the excitation current and the spring piece. Similarly, since the excitation current in the second half remains unchanged, the measured voice coil motor slowly tends to be relatively stationary. The position information of the measured voice coil motor is collected at a fixed frequency during the entire excitation process, and the discrete motion trajectory of the measured voice coil motor is obtained. The collected position set is returned to the host computer for calculation. The host computer performs discrete Fourier transform on the above-mentioned position information set to obtain a set of amplitude-frequency characteristic values of the position information. After removing the direct current component, the maximum amplitude point is obtained, and the frequency value corresponding to the driving point is recorded. Since the object vibrates with the maximum amplitude at the resonance frequency, the above-mentioned frequency point is the resonance frequency of the measured voice coil motor.

[0094] The present application completes the frequency response test in the dynamic response of the voice coil motor in the camera module.

[0095] The present application provides a test method for a voice coil motor in a camera module, based on the test system as described above, the test method comprising:

[0096] setting a plurality of discrete driving currents with equal current values;

[0097] for each discrete driving current:

[0098] the host computer outputs the discrete driving current to the product drive board, and the product drive board drives the measured voice coil motor based on the discrete driving current. After the driving of the discrete driving current is completed, the corresponding position of the measured voice coil motor is determined based on the light spot;

[0099] the host computer determines the position peak value and the mean square error corresponding to all positions based on each position of the measured voice coil motor, and determines the stability of the test system based on the position peak value and the mean square error.

[0100] This test also eliminates the influence of test environment and hardware system abnormalities on other tests.

[0101] The present application provides a multi-channel stable and low-ripple power supply for the measured voice coil motor, and simultaneously supports 1MHz high-speed IIC communication with the measured voice coil motor, so as to obtain the information of the measured voice coil motor and issue relevant parameter instructions to the measured voice coil motor. A synchronization signal is added between the external drive board and the collection board to enhance the synchronization of the internal position data of the measured voice coil motor and the position data of the external multi-axis laser range finder. The internal and external data are quickly transmitted to the host computer through the 100M Ethernet, and the relevant parameters of the measured voice coil motor are calculated by the host computer, which greatly shortens the entire test time of the measured voice coil motor and relieves the contradiction between test precision and production efficiency.

[0102] The above specific embodiments only describe the design principles of the present application, and the shapes and names of the components in the description can be different and are not limited. Therefore, those skilled in the art of the present application can modify or equivalently replace the technical solutions described in the foregoing embodiments; and these modifications and replacements do not deviate from the purpose and technical solutions of the present application, and should all belong to the protection scope of the present application.

Claims

1. A test system of a voice coil motor in a camera module, characterized in that, The test device comprises a non-magnetic platform, a multi-axis laser range finder, a power board, a signal conversion board, a range finder signal output unit, an analog signal acquisition board, a product driving board and an upper computer. The upper computer transmits a driving instruction for driving the voice coil motor to be tested to move along a preset motion track in a linear motion region of the voice coil motor to be tested to the voice coil motor to be tested via the product driving board; the signal conversion board converts a power signal required by the voice coil motor to be tested and a driving signal generated by the product driving board to the voice coil motor to be tested, and a mover of the voice coil motor to be tested moves along the preset motion track; the multi-axis laser range finder determines a position of the voice coil motor to be tested in a multi-axis coordinate system when the voice coil motor to be tested moves and generates position information. The second MCU on the analog signal acquisition board transforms the position information and feeds back the transformed position information to the upper computer, and the upper computer acquires a driving current value and the transformed position information corresponding to the driving current value. The first MCU deployed on the product driving board acquires a temperature output by an internal temperature sensor of the voice coil motor to be tested based on the signal conversion board, and the upper computer issues an instruction for interrupting the test when the temperature exceeds a preset threshold value; a counter in the second MCU controls a delay time between the start of the motion of the mover in the voice coil motor to be tested and the start of the acquisition of the position information by the analog signal acquisition board. Before testing the voice coil motor to be tested, the following operations are repeatedly performed for several times:

2. The test system of claim 1, wherein, A step driving signal from a negative limit to a positive limit is applied to the voice coil motor to be tested, so that the voice coil motor to be tested moves from the negative limit to the positive limit, and a motion track of the voice coil motor to be tested is recorded. The linear motion region of the voice coil motor to be tested is determined according to the plurality of motion tracks acquired. The kernel counter in the second MCU acquires the count of the kernel clock, and controls the delay time between the start of the motion of the mover in the voice coil motor to be tested and the start of the acquisition of the position information by the analog signal acquisition board through the change amount of the kernel clock.

3. The test system of any of claims 1-2, wherein, The multi-axis laser range finder receives reflected light of a reflecting mirror embedded on the mover of the voice coil motor to be tested, and the reflected light converges to form a light spot in a receiving area of the multi-axis laser range finder; when the voice coil motor to be tested moves, the position and size of the light spot are used to determine the position of the voice coil motor to be tested in the multi-axis coordinate system, a multi-axis linear analog signal is generated, and the second MCU on the analog signal acquisition board transforms the position information based on the received multi-axis linear analog signal and feeds back the transformed position information to the upper computer.

4. The test system of any of claims 1-2, wherein, After the test is completed, the upper computer sends a data back transmission instruction to the analog signal acquisition board, and the analog signal acquisition board transmits all the data acquired to the upper computer.

5. The test system of claim 4, wherein, The test method comprises: 6.A method for testing a voice coil motor in a camera module based on the testing system of any one of claims 1-5. The upper computer transmits a coil driving current instruction to the product driving board through a high-speed network port, the product driving board writes the coil driving current instruction into a specified register of the voice coil motor to be tested, the voice coil motor to be tested generates a constant current, the current flows through the coil of the voice coil motor to be tested, the product driving board acquires a voltage value across the coil of the voice coil motor to be tested and a current value flowing through the voice coil motor to be tested, and then transmits the voltage value and the current value to the upper computer through the high-speed network port, and the upper computer calculates a direct current resistance of the coil of the voice coil motor to be tested according to Ohm's law and archives the direct current resistance. The test method comprises:

7. A method for testing a voice coil motor in a camera module based on the testing system of any one of claims 1-5. ​ The host computer preloads a plurality of drive currents for driving the voice coil motor to be tested to a product drive board in batches, wherein each drive current has a current value, the current values of different drive currents are different, and one drive current is loaded each time; the product drive board sends the drive currents to the voice coil motor to be tested in a serial manner through a fixed frequency, and triggers an analog signal acquisition board to obtain the displacement of the voice coil motor to be tested in a plurality of axial directions calculated by a multi-axis laser range finder after each drive current is sent; obtain the displacement corresponding to each drive current; obtain the current value corresponding to each drive current and the displacement corresponding to the drive current, construct a two-dimensional matrix of the current value corresponding to the drive current and the displacement corresponding to the drive current, discretely differentiate the displacement in the two-dimensional matrix, and obtain the sensitivity value of each discrete point corresponding to each drive current; for each drive current, connect the sensitivity values of the discrete points corresponding to the drive current to form a sensitivity curve corresponding to the drive current; select a plurality of sampling points from the sensitivity curves corresponding to each drive current to obtain the test result of the stroke test of the voice coil motor to be tested. 8.A method for testing a voice coil motor in a camera module based on the testing system of any one of claims 1-5. The test method comprises: obtaining the initial state of the internal moving parts of the voice coil motor to be tested, the moving parts including balls and elastic sheets; performing a plurality of motion tests on the voice coil motor to be tested, each motion test comprising: The host computer generates parameters for setting the drive current of the voice coil motor to be tested for cyclic test, and sends the parameters to the product drive board. The product drive board generates IIC communication protocol instructions based on the parameters, sends the IIC communication protocol instructions to the voice coil motor to be tested through the signal adapter, drives the voice coil motor to be tested to move, and the product drive board reads the position information of the position sensor inside the voice coil motor to be tested, thereby determining the stroke of the voice coil motor to be tested; uploading the stroke of the voice coil motor to be tested to the host computer, and the host computer determining the maximum stroke and motion smoothness of the voice coil motor to be tested; obtaining the state of the internal moving parts of the voice coil motor to be tested after the test, and estimating the service life of the voice coil motor to be tested based on the test result of the motion test and in combination with automatic optical inspection. 9.A method for testing a voice coil motor in a camera module based on the testing system of any one of claims 1-5. The test method comprises: The host computer outputs a plurality of discrete, fixed-time, fixed-step incremental square wave current digital step signals. For each square wave current digital step signal: The product drive board drives the voice coil motor to be tested based on the predetermined time interval specified by the step current instruction, and determines the step response time of the voice coil motor to be tested from the driving position to the target position; Based on the light spot, the position of the voice coil motor to be tested is obtained, and the host computer determines the maximum displacement and displacement difference of each step point; Based on the step response time, the maximum displacement and displacement difference of each step point, the step response of the voice coil motor to be tested corresponding to the square wave current digital step signal is determined. 10.A method for testing a voice coil motor in a camera module based on the testing system of any one of claims 1-5, wherein, The test method comprises: a plurality of discrete drive currents with equal current values are set; for each discrete drive current: The host computer outputs the discrete drive current to the product drive board, and the product drive board drives the voice coil motor to be tested based on the discrete drive current. After the discrete drive current is driven, the position corresponding to the voice coil motor to be tested is determined based on the light spot; The host computer determines the position peak value and mean square deviation corresponding to all positions based on each position corresponding to the voice coil motor to be tested, and determines the stability of the test system based on the position peak value and the mean square deviation.

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