Optical image stabilization devices, magnetic field compensation methods, image stabilization control methods, and electronic equipment

Abstract

The application discloses an optical image stabilization device, a magnetic field compensation method thereof, an optical image stabilization control method and an electronic device. The optical image stabilization device comprises a driving module configured to drive a lens to move according to a driving signal. The magnetic field compensation method comprises the following steps: obtaining a preset magnetic field compensation model configured to represent a relationship between a driving current in the driving module and a magnetic field intensity to be compensated; and compensating an initial anti-shake driving signal according to the magnetic field compensation model. The magnetic field compensation method can improve the effect of optical image stabilization control.

Description

Technical Field

[0001] This application relates to the field of optical image stabilization technology, specifically to an optical image stabilization device, a magnetic field compensation method, an image stabilization control method, and an electronic device. Background Technology

[0002] The camera module is the core electronic component for image capture. Smartphones use the camera module to achieve optical imaging and realize functions such as taking photos and videos. The final image quality of the camera module is affected by the focusing effect. Focusing is mainly used to adjust the distance between the lens and the image sensor so that the image focus is on the image sensor, thereby obtaining a clearer image. The final actuator for focusing is the voice coil motor (VCM). Another important application of VCM is optical image stabilization (OIS) in mobile phone camera modules. When using a mobile terminal camera to shoot, there are still problems such as camera shake caused by hand tremors or external bumps, resulting in blurry and unclear images. The principle of OIS is to increase the drive signal to control the voice coil motor (VCM), causing a group of lens elements or photosensitive elements to shift in the opposite direction of the shake, thus counteracting the effects of hand tremors.

[0003] The existing optical image stabilization devices are not very effective and need further improvement. Summary of the Invention

[0004] In view of this, this application provides an optical image stabilization device, a magnetic field compensation method, an image stabilization control method, and an electronic device to further improve the effect of optical image stabilization.

[0005] This application provides a magnetic field compensation method for an optical image stabilization device. The optical image stabilization device includes a driving module, which is used to drive the lens to move according to a driving signal. The magnetic field compensation method includes: acquiring a preset magnetic field compensation model, which is used to characterize the relationship between the driving current in the driving module and the strength of the magnetic field to be compensated; and compensating the initial image stabilization driving signal according to the magnetic field compensation model.

[0006] Optionally, the method for compensating the initial anti-shake drive signal according to the magnetic field compensation model includes: obtaining the current magnetic field strength to be compensated corresponding to the current drive current according to the magnetic field compensation model; obtaining the corresponding compensation signal according to the current magnetic field strength to be compensated; and compensating the initial anti-shake drive signal according to the compensation signal.

[0007] Optionally, the method for compensating the initial image stabilization drive signal according to the compensation signal includes: superimposing the compensation signal with the initial image stabilization drive signal.

[0008] Optionally, it also includes: acquiring a position feedback signal corresponding to the current lens position; and using the position feedback signal to perform negative feedback adjustment on the compensated initial image stabilization drive signal.

[0009] Optionally, the method for compensating the initial image stabilization drive signal according to the compensation signal includes: using the compensation signal to perform negative feedback adjustment on the initial image stabilization drive signal.

[0010] Optionally, it also includes: acquiring a position feedback signal corresponding to the current lens position; the method for compensating the initial image stabilization drive signal according to the compensation signal includes: superimposing the compensation signal onto the position feedback signal to obtain a compensated position feedback signal; and using the compensated position feedback signal to perform negative feedback adjustment on the initial image stabilization drive signal.

[0011] Optionally, the method for determining the magnetic field compensation model includes: sequentially passing multiple driving currents of different magnitudes and directions through the driving module, measuring multiple magnetic field intensities at a fixed position corresponding to each driving current; performing curve fitting on the driving current and the corresponding magnetic field intensities to obtain a fitting curve of driving current-magnetic field intensities, and using the fitting curve as the magnetic field compensation model.

[0012] Optionally, the method for obtaining a curve fitting curve of driving current and corresponding magnetic field strength by curve fitting of the driving current and the corresponding magnetic field strength includes: matching a fitting model with corresponding magnetic field strength distribution characteristics based on multiple driving currents and the distribution characteristics of multiple magnetic field strengths corresponding to each driving current; performing curve fitting of the driving current and the corresponding magnetic field strength based on the fitting model, determining the model parameters of the fitting model, and obtaining the fitting curve.

[0013] Optionally, a Hall position sensor can be used to acquire the position feedback signal corresponding to the current lens position.

[0014] This application also provides a stabilization control method, comprising: compensating an initial stabilization drive signal using a magnetic field compensation method as described above; and controlling the drive module to drive the lens to move using the compensated drive signal.

[0015] This application also provides an optical image stabilization device, comprising: a driving module for driving lens movement according to a driving signal; and a compensation module connected to the driving module for acquiring a preset magnetic field compensation model, wherein the magnetic field compensation model characterizes the relationship between the driving current in the driving module and the strength of the magnetic field to be compensated; and for compensating an initial image stabilization driving signal according to the magnetic field compensation model, and outputting the compensated driving signal to the driving module.

[0016] Optionally, the compensation module is used to: obtain the current magnetic field strength to be compensated corresponding to the current driving current according to the magnetic field compensation model; obtain the corresponding compensation signal according to the current magnetic field strength to be compensated; and compensate the initial anti-shake driving signal according to the compensation signal.

[0017] Optionally, the compensation module is used to receive the initial image stabilization drive signal and superimpose the compensation signal with the initial image stabilization drive signal to compensate the initial image stabilization drive signal; or, the compensation module is used to perform negative feedback adjustment on the initial image stabilization drive signal to compensate the initial image stabilization drive signal.

[0018] Optionally, a feedback module is also included, which is used to acquire a position feedback signal corresponding to the current lens position and use the position feedback signal to perform negative feedback adjustment on the compensated initial image stabilization drive signal.

[0019] Optionally, it also includes a feedback module for acquiring a position feedback signal corresponding to the current lens position; the compensation module is connected to the feedback module for superimposing the compensation signal onto the position feedback signal to obtain a compensated position feedback signal; and the compensated position feedback signal is used to perform negative feedback adjustment on the initial image stabilization drive signal to achieve compensation of the initial image stabilization drive signal.

[0020] Optionally, the feedback module includes a Hall position sensor for detecting the position of the lens and outputting a corresponding position feedback signal.

[0021] Optionally, it includes: a configuration module connected to the compensation module, wherein the configuration module stores multiple preset magnetic field compensation models, each magnetic field compensation model corresponding to a driving module with different characteristics; the configuration module is used to configure the corresponding magnetic field compensation model for the compensation module according to the characteristics of the driving module of the current optical image stabilization device.

[0022] This application also provides an electronic device capable of the image stabilization control method described above; or including an optical image stabilization device as described in any of the above claims.

[0023] The magnetic field compensation method of this application compensates the initial anti-shake drive signal through the magnetic field compensation model, which can eliminate the influence of the interference magnetic field generated by the drive current on position detection, so that the drive signal after compensation of the initial anti-shake drive signal can perform anti-shake control more accurately and improve the optical image stabilization effect.

[0024] Furthermore, the aforementioned magnetic field compensation method requires no external devices and maintains the unchanged structure of the drive module. Magnetic field compensation can be achieved through software or digital circuits by calculating based on the magnetic field compensation model. The algorithm is simple to implement and highly flexible. For different optical image stabilization devices, only the corresponding magnetic field compensation model needs to be adjusted, making it highly versatile. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1a This is a partial structural schematic diagram of an optical image stabilization module according to an embodiment of this application;

[0027] Figure 1b This is a schematic diagram of the structure of the magnet and drive coil in the optical image stabilization module according to an embodiment of this application;

[0028] Figure 1c This is a schematic diagram of the structure of a Hall position sensor placed inside a drive coil according to an embodiment of this application;

[0029] Figure 2 This is a schematic flowchart of a magnetic field compensation method according to an embodiment of this application;

[0030] Figure 3 This is a schematic flowchart of a method for compensating the initial anti-shake drive signal according to an embodiment of this application;

[0031] Figure 4 This is a flowchart illustrating a method for determining a magnetic field compensation model according to an embodiment of this application;

[0032] Figures 5a to 5c This is a schematic diagram of a typical current-magnetic field intensity characteristic curve;

[0033] Figure 6 This is a schematic diagram of the structure of an optical image stabilization device according to an embodiment of this application;

[0034] Figure 7 This is a schematic diagram of the structure of an optical image stabilization device according to another embodiment of this application;

[0035] Figure 8 This is a schematic diagram of the structure of an optical image stabilization device according to another embodiment of this application;

[0036] Figure 9 This is a schematic diagram of the structure of an optical image stabilization device according to another embodiment of this application. Detailed Implementation

[0037] As described in the prior art, current optical image stabilization is not effective and needs further improvement.

[0038] To achieve image stabilization, a position closed-loop control algorithm can be introduced as needed. This involves using position feedback, where a Hall effect position sensor detects changes in the magnetic field to measure the position, and then adjusting the drive signal using negative feedback to achieve image stabilization. However, in existing technologies, the position measured by the Hall effect position sensor often deviates, causing deviations in the drive signal's control of the motor's image stabilization, ultimately affecting the effectiveness of optical image stabilization.

[0039] Further research by the inventors revealed that the deviation in the position information fed back by the Hall position sensor was mainly caused by the presence of interfering magnetic fields in the magnetic field sensed by the Hall position sensor.

[0040] Please refer to Figure 1a This is a partial structural schematic diagram of an optical image stabilization module according to an embodiment of this application.

[0041] Figure 1a This is a simplified structural diagram of a voice coil motor (VCM) in an OIS device. It is a simplified VCM with X-axis and Y-axis drive capability. As can be seen from the diagram, it has four drive magnets 101 at the top and four drive coils 102 below the corresponding magnets.

[0042] The principle of the voice coil motor's operation is as follows: Figure 1b As shown, the dashed lines with arrows represent the distribution of magnetic field lines, and the thinner solid lines with arrows below represent the direction of the current in the coil. According to the left-hand rule, the left side of the drive coil 102 experiences a magnetic force F1, as shown in the diagram, while the right side experiences a magnetic force F0, also as shown in the diagram. F0 and F1 are in the same direction. If the drive coil 102 is fixed as the stator, the drive magnet 101 will move in the opposite direction of F0 due to the reaction force from the drive coil 102. If the lens and drive magnet 101 are fixed together as the mover, the lens can be moved back and forth by the reaction force from the drive coil 102. The distance moved is directly proportional to the magnitude of the force, which is also directly proportional to the magnitude of the current in the drive coil 102; the direction of movement is related to the direction of the current. This is the principle behind lens-based image stabilization. If the driving magnet 101 and the lens are fixed together as the stator, and the driving coil 102 and the CMOS sensor are fixed together as the mover, the driving coil 102, under the force of the magnet, will drive the CMOS sensor to move back and forth. This is the principle of sensor displacement image stabilization. Figure 1a and Figure 1b As shown, two-axis anti-shake control can be achieved by placing the magnet and coil in pairs along the X-axis and Y-axis respectively.

[0043] To achieve precise anti-shake control of the OIS module, a position closed-loop control algorithm is typically introduced. This algorithm requires position feedback, using Hall position sensors for position measurement. Typically, one position sensor is placed on each of the X and Y axes. To reduce size and efficiently utilize the module's internal space, the Hall position sensors are usually placed at the center of the drive coil 102, as shown in 1c. Alternatively, the Hall position sensors can be placed in the middle of one coil 102 on each of the X and Y axes, effectively saving module space. When the magnet 101 moves back and forth along the X-axis, the relative position of the Hall position sensor and the drive magnet 101 changes, causing a corresponding change in the induced magnetic field. This alters the magnitude of the electrical signal output by the Hall position sensor, allowing the determination of the displacement and thus the position measurement. However, since the current-carrying wire also generates a magnetic field, the magnitude of which is related to the magnitude of the current in the drive coil 102. The direction of the magnetic field generated by the current-carrying wire is determined by the right-hand rule. This magnetic field will be superimposed on the magnetic field of the drive magnet 101 and act together on the Hall position sensor, thereby causing the position measured by the Hall position sensor to deviate, ultimately resulting in poor optical image stabilization.

[0044] Even if the Hall position sensor is not located inside the drive coil 102, but outside the drive coil 102, it will still be affected by the interference magnetic field generated by the drive coil 102.

[0045] Without altering the design principles of current optical image stabilization modules, the generation of an interfering magnetic field by the drive coil 102 is unavoidable. To eliminate the influence of this interfering magnetic field, superimposing a reverse compensating magnetic field is a readily conceivable solution. The generation of the compensating magnetic field relies on a structure capable of generating a magnetic field, such as a compensating coil or a compensating magnet, to counteract the interfering magnetic field. However, the inventors discovered that this approach requires adding hardware structures, complicating the image stabilization device and contradicting the initial goal of reducing module complexity and size. Furthermore, the design and implementation of hardware compensation are limited by manufacturing processes, requiring different hardware compensation structures for different structures, making mass production difficult. It also suffers from poor versatility and adaptability, with the compensation effect easily affected by ambient temperature and circuit structure, resulting in poor consistency and hindering production line yield, significantly increasing production costs and reducing economic efficiency.

[0046] Based on the above research, after ruling out various hardware improvement solutions, the inventors creatively proposed a computational method to calculate the magnitude of the interfering magnetic field and compensate for it, thereby eliminating its influence and improving the optical image stabilization effect. To this end, the applicant proposed a new magnetic field compensation method for optical image stabilization modules. This method uses an algorithmic model to compensate for the magnetic field generated by the coil, thus offsetting its impact on the position detection of the Hall position sensor, improving the accuracy of the Hall position sensor's position measurement, and ultimately solving the problem of poor optical image stabilization performance.

[0047] The technical solutions in the embodiments of this application 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 this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In the absence of conflict, the following embodiments and their technical features can be combined with each other.

[0048] Please refer to Figure 2 This is a flowchart illustrating a magnetic field compensation method for an optical image stabilization device according to an embodiment of this application.

[0049] The optical image stabilization device includes a drive module, which is controlled by a drive signal. The drive signal controls the magnitude of the drive current within the drive module, thereby controlling the displacement of the lens driven by the drive module.

[0050] The drive module can be a voice coil motor, such as... Figures 1a to 1c As shown, the system includes a drive coil and a magnet. A drive signal controls the drive current flowing through the drive coil, thereby controlling the relative position between the magnet and the drive coil. In other embodiments, the drive module may have other structures, similarly using a drive signal to drive the magnitude of the drive current within the module to drive the displacement of the lens. The drive current flowing through the conductor not only causes the coil to experience electromagnetic force within the magnetic field but also causes the coil itself to generate a magnetic field. When using a Hall effect position sensor to detect lens displacement by detecting changes in the magnetic field, a portion of the magnetic field actually received by the Hall effect position sensor is generated by the coil, interfering with the detection results and requiring compensation for this portion of the magnetic field.

[0051] In this embodiment, the magnetic field compensation method includes the following steps:

[0052] Step S101: Obtain a preset magnetic field compensation model, which is used to characterize the relationship between the driving current in the driving module and the strength of the magnetic field to be compensated.

[0053] There is a certain relationship between the interference magnetic field generated by the driving current and the magnetic field strength to be compensated. Due to the different structures of the driving modules used in different optical image stabilization devices, such as the different shapes, magnetization methods and magnetization amounts of magnets; the different shapes and number of turns of the driving coils; and the different placement of the Hall position sensors used to detect the magnetic field, the final relationship between the magnetic field strength to be compensated and the driving current also varies.

[0054] In embodiments of the present invention, a matching magnetic field compensation model is pre-set for a specific optical image stabilization device. This model accurately reflects the relationship between the driving current and the strength of the magnetic field to be compensated. Based on this model, the strength of the magnetic field to be compensated can be obtained under a specific driving current. The pre-set magnetic field compensation model can be obtained in advance through testing or simulation. Different magnetic field compensation models can be configured for different optical image stabilization devices. For the same optical image stabilization device, only one modeling is needed to obtain the corresponding magnetic field compensation model, which is universal for the same optical image stabilization device.

[0055] Step S102: Compensate the initial anti-shake drive signal according to the magnetic field compensation model.

[0056] When lens position shake is detected, the electronic device containing the optical image stabilization (OIS) sends a corresponding initial drive signal to the OIS based on the shake condition for image stabilization control. During the operation of the OIS, as the drive current changes, the initial OIS drive signal can be compensated in real time or at a set compensation frequency using a magnetic field compensation model. If necessary, the compensated initial OIS drive signal can undergo further processing, such as filtering, gain adjustment, and negative feedback adjustment, before being input to the drive module.

[0057] The magnetic field compensation method of this embodiment compensates the initial anti-shake drive signal through the magnetic field compensation model, which can eliminate the influence of the interference magnetic field generated by the drive current on position detection, so that the drive signal after compensation of the initial anti-shake drive signal can perform anti-shake control more accurately and improve the optical image stabilization effect.

[0058] The aforementioned magnetic field compensation method requires no external devices and maintains the unchanged structure of the drive module. Magnetic field compensation can be achieved through software or digital circuits based on a magnetic field compensation model. The algorithm is simple to implement and highly flexible. For different optical image stabilization devices, only the corresponding magnetic field compensation model needs to be adjusted, making it highly versatile.

[0059] Please refer to Figure 3 This is a schematic diagram of a method for compensating the initial anti-shake drive signal in one embodiment of the present invention.

[0060] In this embodiment, the method for compensating the initial anti-shake drive signal in step S102 specifically includes the following steps:

[0061] Step S201: Obtain the current magnetic field strength to be compensated corresponding to the current driving current according to the magnetic field compensation model.

[0062] Since the magnetic field compensation model characterizes the relationship between the driving current and the magnetic field strength to be compensated, the corresponding current interference magnetic field strength that needs to be compensated, i.e. the magnetic field strength to be compensated, can be calculated based on the current driving current.

[0063] Step S202: Obtain the corresponding compensation signal based on the current magnetic field strength to be compensated.

[0064] The compensation signal can be an electrical signal corresponding to the magnitude of the magnetic field strength to be compensated, such as a voltage or current signal.

[0065] Step S203: Compensate the initial anti-shake drive signal according to the compensation signal.

[0066] In some embodiments, a Hall position sensor is typically used to detect changes in the magnetic field caused by position changes. The Hall position sensor detects the magnetic field and outputs a Hall voltage corresponding to the magnetic field, and the voltage signal represents the detected position information. Therefore, in step S202, the same conversion relationship between magnetic field strength and voltage signal of the Hall position sensor can be used to convert the current magnetic field strength to be compensated into a corresponding voltage signal, which is then used as the compensation signal. In other embodiments, the correspondence between the magnetic field strength to be compensated and the compensation signal can be adjusted and calibrated according to the actual compensation effect to maximize the compensation effect of the compensation signal.

[0067] In some embodiments, in step S203, the compensation signal can be directly superimposed with the initial anti-shake drive signal to achieve the compensation.

[0068] To achieve the superposition, the compensation signal and the initial image stabilization drive signal are of the same type. For ease of calculation, both the compensation signal and the initial image stabilization drive signal can be digital signals. In other embodiments, they can also be analog signals.

[0069] In some embodiments, the initial image stabilization drive signal is typically a voltage signal, and the corresponding compensation signal is also a voltage signal. The compensation signal can be superimposed on the initial image stabilization drive signal to achieve compensation. In other embodiments, the initial image stabilization drive signal can also be a current signal, and the corresponding compensation signal can also be a current signal, to facilitate signal superposition.

[0070] In step S203, since the driving current generates different magnetic field directions under different current directions, if the direction of the generated interference magnetic field is consistent with the direction of the effective magnetic field for position detection, the value of the compensation signal needs to be subtracted from the initial anti-shake driving signal. If the direction of the generated interference magnetic field is opposite to the direction of the effective magnetic field for position detection, the value of the compensation signal needs to be added to the initial anti-shake driving signal. Therefore, the superposition can be either numerical addition or numerical subtraction.

[0071] In some embodiments, the compensation signal may have a positive or negative sign to indicate the direction of the magnetic field to be compensated. In this case, the compensation signal can be directly added to the initial anti-shake drive signal with a sign to achieve compensation. In other embodiments, the compensation signal may be unsigned. Depending on the direction of the magnetic field to be compensated, the "superposition" during the compensation process is set to add (if the interfering magnetic field and the effective magnetic field are in the same direction) or subtract (if the interfering magnetic field and the effective magnetic field are in opposite directions) the value of the compensation signal. The value is the absolute magnitude of the signal.

[0072] In other embodiments, the gain of the compensation signal can be further adjusted to compensate the initial anti-shake drive signal according to a certain ratio. The ratio can be less than 1 or greater than 1, and can be adjusted according to the actual compensation effect.

[0073] In the above embodiment, in step S203, compensation is achieved by directly superimposing the compensation signal and the initial anti-shake drive signal, and then the compensated drive signal is adjusted by negative feedback or otherwise processed. On the one hand, directly superimposing the compensation signal and the initial anti-shake drive signal can avoid affecting other signal paths, such as feedback loops. On the other hand, since the initial anti-shake drive signal is located at the input end of the optical image stabilization device, and the input signal frequency is usually low; and the frequency of the interfering magnetic field is also usually low, using a lower frequency compensation signal to compensate the initial anti-shake drive signal at the input end results in a compensation frequency that is closer to the interference frequency of the interfering magnetic field, leading to a better compensation effect.

[0074] In some other embodiments, in step S203, the compensation signal can be used to compensate the initial anti-shake drive signal in the form of negative feedback adjustment through a feedback loop.

[0075] In some embodiments, the magnetic field compensation method further includes: acquiring a position feedback signal corresponding to the current lens position; and using the position feedback signal to perform negative feedback adjustment on the compensated initial image stabilization drive signal. Through negative feedback adjustment, the error between the lens position and the target position is reduced, ultimately allowing the lens position to reach the target position, achieving stable closed-loop control of the lens position. In some embodiments, a Hall position sensor is used to acquire the position feedback signal corresponding to the current lens position.

[0076] Specifically, in some embodiments, a position feedback signal corresponding to the current lens position can be obtained; the compensation signal is superimposed on the position feedback signal to obtain a compensated position feedback signal; and the compensated position feedback signal is used to perform negative feedback adjustment on the initial image stabilization drive signal. The specific method of superimposing the compensation signal on the position feedback signal can refer to the analysis of superimposing the compensation signal on the initial shake drive signal in the aforementioned embodiments. During the process of superimposing the compensation signal on the position feedback signal, the relationship between the direction of the interfering magnetic field and the effective magnetic field used for position detection should also be considered. A signed addition should be performed, or, depending on whether the directions are the same or different, the value of the compensation signal should be added (if the interfering magnetic field is in the opposite direction to the effective magnetic field) or subtracted (if the interfering magnetic field is in the same direction as the effective magnetic field) to the position feedback signal to reduce the influence of the interfering magnetic field on the accuracy of the position feedback signal, thereby improving the accuracy of the final negative feedback adjustment.

[0077] In some embodiments, the initial anti-shake control can also be directly adjusted using the compensation signal to achieve the compensation. Since the compensation signal is generated by the interfering magnetic field, when the interfering magnetic field and the effective magnetic field are in opposite directions, a positive compensation signal value is used for negative feedback adjustment; when the interfering magnetic field and the effective magnetic field are in the same direction, a negative compensation signal value is used for negative feedback adjustment.

[0078] In this application, the positive and negative values ​​of the compensation signal used in the compensation process can be set according to the direction of the interfering magnetic field during the formation of the compensation signal, or the sign can be set according to the direction of the interfering magnetic field after the compensation signal is formed.

[0079] In the above embodiment, in step S203, the initial anti-shake drive signal is compensated through a negative feedback loop. Since the signal frequency of the negative feedback loop is usually high, the frequency of the compensation signal needs to be adjusted to the signal frequency of the negative feedback loop. This can increase the update frequency of the compensation signal, reduce latency, and improve the compensation effect.

[0080] Embodiments of the present invention also provide Figure 2 The method for determining the preset magnetic field compensation model used in step S101.

[0081] Please refer to Figure 4 The following is a flowchart illustrating a method for determining a magnetic field compensation model according to an embodiment of the present invention, comprising the following steps:

[0082] Step S301: Pass multiple driving currents of different magnitudes and directions through the driving module in sequence, and measure the multiple magnetic field strengths at a fixed position corresponding to each driving current.

[0083] Because different drive modules employ different structures—such as different magnet shapes, magnetization methods, and magnetization amounts; different coil shapes and number of turns; and different placement of Hall position sensors—the resulting magnetic field interference also varies. Therefore, it is necessary to first identify the distribution characteristics of the magnetic field generated by the target drive module when a drive current is applied, and then set a targeted magnetic field compensation model to eliminate the influence of interfering magnetic fields to the greatest extent. Currents of different magnitudes and directions are applied to the drive module, and the magnetic field strength at a fixed position is observed and recorded to obtain multiple sets of current-magnetic field strength data.

[0084] Step S302: Perform curve fitting on the driving current and the corresponding magnetic field strength to obtain the fitting curve of driving current-magnetic field strength, and use the fitting curve as the magnetic field compensation model.

[0085] Based on the multiple driving currents applied and the measured distribution characteristics of multiple magnetic field strengths corresponding to each driving current, a fitting model with the corresponding magnetic field strength distribution characteristics is matched. Specifically, a curve is plotted with the driving current as the abscissa and the magnetic field strength as the ordinate, using the data recorded in step S301. The current-magnetic field strength distribution characteristics can be roughly determined from the curve, and the corresponding fitting model can be matched accordingly. This determination process can be achieved through direct observation or software calculation.

[0086] When the lens position is detected by a Hall position sensor, the influence of interfering magnetic fields mainly affects the detection results of the Hall position sensor. In some embodiments, in step S301, the magnetic field strength of the drive current at the actual placement position of the Hall position sensor (e.g., inside or outside the drive coil) can be measured according to the actual placement relationship between the Hall position sensor and the drive current (i.e., the drive coil) in the optical image stabilization device. This results in a more accurate compensation effect for the model constructed from the detected data.

[0087] In other embodiments, the magnetic field strength can also be measured at a fixed location near the drive current. For example, if the Hall position sensor is located at the center of the drive coil, since there will be a certain positional deviation between the Hall position sensor and the center of the drive coil in the vertical position, the magnetic field strength at a distance above or below the center of the drive coil plane can be detected. The accuracy of the model can then be improved through subsequent calibration.

[0088] In step S302, based on the distribution characteristics of the measured driving current and magnetic field strength, the corresponding model function can be used for fitting. Figures 5a-5c Here are some typical examples of current-magnetic field strength characteristic curves.

[0089] Please refer to Figure 5aThe current-magnetic field intensity curve is a first-order linear characteristic curve.

[0090] The magnitude of the magnetic field strength generated by the coil after a driving current I is applied satisfies:

[0091] Mag_coil=k·I+b

[0092] Where Mag_coil is the magnitude of the magnetic field strength generated by the coil after a current I is passed through it, and k and b are fitting coefficients.

[0093] Please refer to Figure 5b The current-magnetic field intensity curve is a high-order linear characteristic curve.

[0094] The magnitude of the magnetic field strength generated by the coil after a driving current I is applied satisfies:

[0095]

[0096] Where Mag_coil represents the magnitude of the magnetic field strength generated by the coil after a current I is passed through it, A0, A1, ..., A n is the fitting coefficient, and n is the order.

[0097] Please refer to Figure 5c The current-magnetic field intensity curve is a piecewise linear characteristic, with three segments as an example.

[0098] The magnitude of the magnetic field strength generated by the coil after a driving current I is applied satisfies:

[0099]

[0100] In the formula, Mag_coil represents the magnitude of the magnetic field strength generated after the coil is energized with current I, and k0, k1, k2, b0, b1, and b2 are all fitting coefficients.

[0101] After selecting the fitting model, the data of driving current and magnetic field strength recorded in step S301 are used to perform curve fitting, and the fitting coefficients in the corresponding model are calculated to determine the model parameters (i.e. fitting coefficients) of the fitting model, so as to obtain a specific fitting curve, and the fitting curve is used as the magnetic field compensation model.

[0102] By judging the fitting error, we can determine whether the fitted curve is suitable. If the fitting error is too large, we need to replace the fitting model and refit until the fitting error requirement is met. The fitting error can be set according to the adjustment accuracy of the lens position, so that the deviation of the fitting error value from the position adjustment is less than the adjustment accuracy of the lens position.

[0103] The distribution characteristic curves listed above are merely examples. In reality, the magnetic field distribution of the interference magnetic field generated by the driving current may be more complex. In such cases, the driving current-magnetic field strength can be piecewise fitted based on the distribution characteristics, and a suitable fitting model can be matched to each segment of the distribution curve. Specifically, the segmentation can be performed manually by observing the recorded current-magnetic field strength data distribution characteristics, or it can be done by a computer. For example, by calculating the rate of change of the second derivative at each location; if the rate of change of the second derivative is too large, that point is used as the segmentation point.

[0104] The above embodiments test the target optical image stabilization device by pre-setting a matching magnetic field compensation model for use in actual image stabilization control. This process can be achieved simply through a fitting algorithm and basic testing, without requiring any modification to the structure of the optical image stabilization device, making it easy to implement and cost-effective. Once the model is determined, the same magnetic field compensation model can be used for the same optical image stabilization device. Even considering deviations in ambient temperature, manufacturing process, etc., which may result in slight differences in compensation effects, only the model parameters in the magnetic field compensation model need to be adjusted to adjust the compensation effect.

[0105] Embodiments of the present invention also provide a method for controlling the image stabilization of an optical image stabilization device. The initial image stabilization drive signal is compensated using the magnetic field compensation method described in any of the above embodiments; then, the compensated drive signal is used to control the drive module within the optical image stabilization device to drive the lens movement. Since the compensated drive signal eliminates the influence of the interfering magnetic field generated by the drive current, the image stabilization control can be more accurate.

[0106] Embodiments of the present invention also provide an optical image stabilization device.

[0107] Please refer to Figure 6 This is a schematic diagram of the structure of an optical image stabilization device according to an embodiment of this application.

[0108] The optical image stabilization device includes a drive module 501 and a compensation module 502.

[0109] The drive module 501 is used to drive the lens to move according to the drive signal.

[0110] The compensation module 502 is connected to the drive module 501 and is used to obtain a preset magnetic field compensation model. The magnetic field compensation model is used to characterize the relationship between the drive current in the drive module 501 and the strength of the magnetic field to be compensated. According to the magnetic field compensation model, the initial anti-shake drive signal Target is compensated, and the compensated drive signal Target_C is output to the drive module 501.

[0111] In some embodiments, the compensation module 502 is used to obtain the current magnetic field strength to be compensated corresponding to the current driving current according to the magnetic field compensation model; obtain the corresponding compensation signal according to the current magnetic field strength to be compensated; and compensate the initial anti-shake driving signal Target according to the compensation signal.

[0112] In some embodiments, the compensation module 502 is used to receive the initial compensation signal Target, and superimpose the compensation signal with the initial anti-shake drive signal Target to achieve compensation of the initial anti-shake drive signal, and output the compensated drive signal Target_C.

[0113] In other embodiments, the compensation module 502 may also be disposed in the feedback loop and used to perform negative feedback adjustment on the initial anti-shake drive signal Target through the compensation signal to achieve compensation of the initial anti-shake drive signal.

[0114] Please refer to Figure 7 This is a schematic diagram of the structure of an optical image stabilization device according to another embodiment of this application.

[0115] In this embodiment, Figure 6 Based on the embodiment shown, the optical image stabilization device further includes a feedback module 701.

[0116] The feedback module 701 is used to acquire a position feedback signal corresponding to the current lens position, and to use the position feedback signal to perform negative feedback adjustment on the compensated initial image stabilization drive signal. In some embodiments, the feedback module 701 may include a Hall position sensor, which detects changes in the magnetic field within the drive module 501 to detect the position of the lens and outputs a corresponding position feedback signal FB.

[0117] Please refer to Figure 8 This is a schematic diagram of the structure of an optical image stabilization device according to another embodiment of this application.

[0118] In this embodiment, the optical image stabilization device also includes a feedback module 701, which is used to acquire a position feedback signal corresponding to the current lens position.

[0119] In this embodiment, the compensation module 702 is connected to the feedback module 502 and compensates the initial anti-shake drive signal in the feedback loop. Specifically, the feedback module 502 is used to superimpose the compensation signal onto the position feedback signal to obtain a compensated position feedback signal FB_C; and to use the compensated position feedback signal FB_C to perform negative feedback adjustment on the initial anti-shake drive signal Target, so as to achieve compensation of the initial anti-shake drive signal and obtain a compensated drive signal Target_FC.

[0120] Of course, in other embodiments, the compensation signal output by the compensation module can also be used to directly adjust the initial anti-shake drive signal using negative feedback. The negative feedback adjustment using the compensation signal can be performed simultaneously or sequentially with the negative feedback adjustment of the position feedback signal.

[0121] The above embodiments provide two methods for compensation: setting the compensation module in the input path and the feedback loop. Those skilled in the art can reasonably set the specific position of the compensation module and the signal connection relationship according to the actual circuit of the optical image stabilization device based on these two design ideas, all of which are within the protection scope of this application.

[0122] Please refer to Figure 9 This is a schematic diagram of the structure of an optical image stabilization device according to another embodiment of this application.

[0123] In this embodiment, the optical image stabilization module further includes a configuration module 901, which is connected to the compensation module 502. The configuration module 901 stores multiple preset magnetic field compensation models, each corresponding to a driving module with different characteristics. The configuration module 901 is used to configure the corresponding magnetic field compensation model for the compensation module 501 according to the characteristics of the driving module 501 of the current optical image stabilization device, so as to achieve the best compensation effect. Figure 9 Other modules are not shown.

[0124] The method for determining the multiple preset magnetic field compensation models can be referred to the foregoing embodiments, and will not be repeated here.

[0125] The configuration module 901 can be a register with storage capacity. The compensation module 501 includes at least digital circuitry for calculating the magnetic field strength to be compensated based on the magnetic field compensation model and converting it into a compensation signal through a suitable conversion relationship. The configuration module 901 can configure the operational logic of the digital circuitry to configure the matching magnetic field compensation model to the compensation module 501. The configuration module 901 is also used to modify the model parameters of the magnetic field compensation model to correct the model. The configuration module 901 is also used to configure the compensation module 801 to be located on the input path or the feedback path by modifying the connection relationship of the circuits within the compensation module 801, for example, connecting the output terminal of the compensation signal of the compensation module 801 to the input terminal of the initial anti-shake drive signal, or connecting the output terminal of the compensation signal to the feedback signal output terminal of the feedback loop, etc.

[0126] Embodiments of this application also provide an electronic device capable of executing the image stabilization control method as described in any of the above embodiments; or including the optical image stabilization device as described in any of the above embodiments. The electronic device may be a smartphone, tablet computer, handheld camera, handheld camcorder, or other electronic device requiring image stabilization for shooting.

[0127] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, such as the combination of technical features between embodiments, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A magnetic field compensation method of an optical image stabilization device, the optical image stabilization device comprising a driving module for driving a lens to move according to a driving signal, characterized in that, The magnetic field compensation method comprises: obtaining a preset magnetic field compensation model, the magnetic field compensation model being used to represent a relationship between a driving current in the driving module and a magnetic field intensity to be compensated; compensating an initial anti-shake driving signal according to the magnetic field compensation model; The method for determining the magnetic field compensation model comprises: sequentially inputting a plurality of driving currents with different sizes and directions into the driving module, and measuring a plurality of magnetic field intensities corresponding to the driving currents at a fixed position; performing curve fitting on the driving currents and the corresponding magnetic field intensities, and obtaining a fitting curve of the driving current-magnetic field intensity, so as to obtain the magnetic field compensation model.

2. The magnetic field compensation method of claim 1, wherein, The method for compensating the initial anti-shake driving signal according to the magnetic field compensation model comprises: obtaining a current magnetic field intensity to be compensated corresponding to a current driving current according to the magnetic field compensation model; obtaining a corresponding compensation signal according to the current magnetic field intensity to be compensated; and compensating the initial anti-shake driving signal according to the compensation signal.

3. The magnetic field compensation method of claim 2, wherein, The method for compensating the initial anti-shake driving signal according to the compensation signal comprises: superimposing the compensation signal and the initial anti-shake driving signal.

4. The magnetic field compensation method of claim 3, wherein, Further comprising: obtaining a position feedback signal corresponding to a current lens position; and performing negative feedback adjustment on the initial anti-shake driving signal after compensation by using the position feedback signal.

5. The magnetic field compensation method of claim 2, wherein, The method for compensating the initial anti-shake driving signal according to the compensation signal comprises: performing negative feedback adjustment on the initial anti-shake driving signal by using the compensation signal.

6. The magnetic field compensation method according to claim 5, characterized in that, Further comprising: obtaining a position feedback signal corresponding to a current lens position; The method for compensating the initial anti-shake driving signal according to the compensation signal comprises: superimposing the compensation signal to the position feedback signal to obtain a position feedback signal after compensation; and performing negative feedback adjustment on the initial anti-shake driving signal by using the position feedback signal after compensation. The method for performing curve fitting on the driving currents and the corresponding magnetic field intensities to obtain a fitting curve of the driving current-magnetic field intensity comprises: matching a fitting model with a corresponding magnetic field intensity distribution characteristic according to the plurality of driving currents input and the distribution characteristics of the plurality of magnetic field intensities corresponding to the driving currents; and performing curve fitting on the driving currents and the corresponding magnetic field intensities according to the fitting model, and determining model parameters of the fitting model to obtain the fitting curve.

7. The magnetic field compensation method of claim 1, wherein, The position feedback signal corresponding to the current lens position is obtained by using a Hall position sensor.

8. The magnetic field compensation method according to any one of claims 4 or 6, characterized in that, The method comprises:

9. A method of anti-shake control, characterized by, compensating an initial anti-shake driving signal by using the magnetic field compensation method in any one of claims 1 to 8; controlling the driving module to drive the lens to move by using the driving signal after compensation. The method comprises:

10. An optical image stabilizer apparatus characterized by comprising: a driving module, which is used to drive the lens to move according to a driving signal; a compensation module, which is connected to the driving module and is used to obtain a preset magnetic field compensation model, the magnetic field compensation model being used to represent a relationship between a driving current in the driving module and a magnetic field intensity to be compensated; compensate an initial anti-shake driving signal according to the magnetic field compensation model, and output the driving signal after compensation to the driving module. ​ The method for determining the magnetic field compensation model comprises: sequentially inputting a plurality of driving currents with different sizes and directions into the driving module, and measuring a plurality of magnetic field strengths at a fixed position corresponding to each driving current; performing curve fitting on the driving current and the corresponding magnetic field strength to obtain a fitting curve of the driving current-magnetic field strength, and taking the fitting curve as the magnetic field compensation model.

11. The optical image stabilization apparatus according to claim 10, wherein Comprise: The compensation module is configured to obtain a current to-be-compensated magnetic field strength corresponding to a current driving current according to the magnetic field compensation model; According to the current to-be-compensated magnetic field strength, a corresponding compensation signal is obtained; and the initial anti-shake driving signal is compensated according to the compensation signal.

12. The optical image stabilizer according to claim 11, characterized by The compensation module is configured to receive the initial anti-shake driving signal, and superimpose the compensation signal on the initial anti-shake driving signal to compensate the initial anti-shake driving signal; or the compensation module is configured to perform negative feedback adjustment on the initial anti-shake driving signal to compensate the initial anti-shake driving signal.

13. The optical image stabilizer according to claim 12, wherein Further comprising a feedback module configured to obtain a position feedback signal corresponding to a current lens position, and perform negative feedback adjustment on the compensated initial anti-shake driving signal using the position feedback signal. 14.The optical image stabilization apparatus according to claim 12, wherein Further comprising a feedback module configured to obtain a position feedback signal corresponding to a current lens position; the compensation module is connected to the feedback module and configured to superimpose the compensation signal on the position feedback signal to obtain a compensated position feedback signal; and perform negative feedback adjustment on the initial anti-shake driving signal using the compensated position feedback signal to compensate the initial anti-shake driving signal.

15. The optical image stabilisation apparatus according to claim 13 or 14, wherein, The feedback module comprises a Hall position sensor configured to detect the position of the lens and output a corresponding position feedback signal.

16. The optical image stabilization apparatus according to claim 10, wherein Comprise: A configuration module connected to the compensation module, wherein a plurality of preset magnetic field compensation models are stored in the configuration module, and each magnetic field compensation model corresponds to a driving module with different characteristics; The configuration module is configured to configure a corresponding magnetic field compensation model for the compensation module according to the characteristics of the driving module of the current optical image stabilization device.

17. An electronic device, comprising: Can execute the anti-shake control method as claimed in claim 9; or comprise the optical image stabilization device as claimed in any one of claims 10 to 16.

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