阅读说明：本技术 一种提取误差法修正闭环音圈马达磁场两端非线性的方法 (Method for correcting nonlinearity of two ends of magnetic field of closed-loop voice coil motor by extraction error method ) 是由 陈珍珍 陈君飞 张洪 于 2021-08-26 设计创作，主要内容包括：本发明公开了一种提取误差法修正闭环音圈马达磁场两端非线性的装置和方法,该方法包含：提取所述霍尔组件在所述磁铁所产生的磁场中感应到的磁场强度的非线性误差；根据提取的非线性误差对所述霍尔组件在所述磁铁所产生的磁场中感应到的磁场强度进行修正。本发明提供的霍尔器件磁场非线性修正的方法,能很好地修正磁场两端的非线性度,从使马达具有很好的线性行程,进而可以提高手机相机的拍照质量。(The invention discloses a device and a method for correcting nonlinearity of two ends of a magnetic field of a closed-loop voice coil motor by an extraction error method, wherein the method comprises the following steps: extracting a non-linear error of a magnetic field strength induced by the hall assembly in a magnetic field generated by the magnet; and correcting the magnetic field intensity induced by the Hall assembly in the magnetic field generated by the magnet according to the extracted nonlinear error. The method for correcting the nonlinearity of the magnetic field of the Hall device can well correct the nonlinearity of two ends of the magnetic field, so that the motor has good linear stroke, and further the photographing quality of a mobile phone camera can be improved.)

1. An apparatus for correcting nonlinearity at two ends of a magnetic field of a closed-loop voice coil motor by an extraction error method, comprising:

a magnet comprising a magnetic south pole and a magnetic north pole;

a hall assembly positioned in the magnetic field generated by the magnet, comprising:

the first Hall device is used for sensing the magnetic field intensity of the position where the first Hall device is located; and

the second Hall device is arranged at a distance from the first Hall device and used for sensing the magnetic field intensity of the position where the second Hall device is located;

wherein the first Hall device and the second Hall device are located on the same side of the magnet; the output end of the voice coil motor can drive the magnet or the Hall assembly to move; and in the moving process, the distance between the first Hall device and the second Hall device is always kept unchanged.

2. The apparatus of claim 1, wherein the output of the vcm is configured to move the magnet or the hall element in a first direction within a first section; the direction from the first Hall device to the second Hall device is parallel to or coincided with the first direction; in an initial position where the voice coil motor is not activated, both end points of the first section are symmetrically disposed about a middle position of the magnet.

3. The apparatus for error extraction based correction of nonlinearity across a closed-loop vcm magnetic field of claim 2, wherein said first segment has a length of 400 μm.

4. A method for applying the method of any one of claims 1 to 3 to an apparatus for correcting nonlinearity across a magnetic field of a closed-loop vcm, comprising:

extracting a non-linear error of a magnetic field strength induced by the hall assembly in a magnetic field generated by the magnet;

and correcting the magnetic field intensity induced by the Hall assembly in the magnetic field generated by the magnet according to the extracted nonlinear error.

5. The method of claim 4, wherein extracting the non-linear error in the magnetic field strength induced by the Hall assembly in the magnetic field generated by the magnet comprises:

acquiring a characteristic curve of an added value of the magnetic field intensity of the Hall assembly in a linear magnetic field;

acquiring a characteristic curve of an added value of the magnetic field intensity of the Hall assembly in a nonlinear magnetic field generated by the magnet;

and calculating to obtain the nonlinear error of the magnetic field intensity induced by the Hall assembly in the nonlinear magnetic field generated by the magnet according to the characteristic curve of the added value of the magnetic field intensity of the Hall assembly in the linear magnetic field and the characteristic curve of the added value of the magnetic field intensity of the Hall assembly in the nonlinear magnetic field generated by the magnet.

6. The method of claim 5, wherein obtaining a characteristic curve of an added value of a magnetic field strength of the Hall assembly in a nonlinear magnetic field generated by the magnet comprises:

the position of the Hall assembly is controlled through the voice coil motor, so that the magnetic field intensity sensed by the first Hall assembly and the second Hall assembly when the Hall assembly is at different positions is obtained;

and adding the magnetic field strengths sensed by the first Hall assembly and the second Hall assembly when the Hall assemblies are at different positions to obtain a characteristic curve of the added value of the magnetic field strengths of the Hall assemblies in the nonlinear magnetic field generated by the magnet.

7. The method of claim 6, wherein extracting the non-linear error in the magnetic field strength induced by the hall assembly in the magnetic field generated by the magnet comprises:

acquiring a characteristic curve of a subtraction value of the magnetic field intensity of the Hall assembly in a linear magnetic field;

acquiring a characteristic curve of a subtraction value of the magnetic field intensity of the Hall assembly in a nonlinear magnetic field generated by the magnet;

and calculating to obtain the nonlinear error of the magnetic field intensity induced by the Hall assembly in the nonlinear magnetic field generated by the magnet according to the characteristic curve of the subtraction value of the magnetic field intensity of the Hall assembly in the linear magnetic field and the characteristic curve of the subtraction value of the magnetic field intensity of the Hall assembly in the nonlinear magnetic field generated by the magnet.

8. The method of claim 7, wherein obtaining a characteristic curve of a subtracted value of a magnetic field strength of the hall assembly in a nonlinear magnetic field generated by the magnet comprises:

the position of the Hall assembly is controlled through the voice coil motor, so that the magnetic field intensity sensed by the first Hall assembly and the second Hall assembly when the Hall assembly is at different positions is obtained;

and subtracting the magnetic field strengths sensed by the first Hall assembly and the second Hall assembly when the Hall assemblies are at different positions to obtain a characteristic curve of a subtraction value of the magnetic field strengths of the Hall assemblies in the nonlinear magnetic field generated by the magnet.

9. The method of claim 5, wherein correcting the magnetic field strength induced by the Hall assembly in the magnetic field generated by the magnet based on the extracted non-linear error comprises:

when the voice coil motor is in a nonlinear magnetic field, setting a magnetic field intensity subtraction value induced by the first Hall device and the second Hall device at an initial position as a magnetic field subtraction value induced by two Hall devices of the linear magnetic field;

when the voice coil motor moves, taking a magnetic field subtraction value or an addition value sensed by two Hall devices in a linear magnetic field as a reference, and taking the change quantity of the magnetic field intensity subtraction value sensed by the first Hall device and the second Hall device as a nonlinear error;

when the voice coil motor moves, the nonlinear error is subtracted from the added value of the magnetic field strengths sensed by the first Hall device and the second Hall device, and the correction of the magnetic field strength sensed by the Hall assembly in the magnetic field generated by the magnet is completed.

10. The method of claim 5, wherein correcting the magnetic field strength induced by the Hall assembly in the magnetic field generated by the magnet based on the extracted non-linear error comprises:

when the voice coil motor is in a nonlinear magnetic field, setting the magnetic field intensity added value induced by the first Hall device and the second Hall device at the initial position as the magnetic field added value induced by the two Hall devices in the linear magnetic field;

when the voice coil motor moves, the variation of the added magnetic field intensity values sensed by the first Hall device and the second Hall device is obtained by taking the added magnetic field values sensed by the two Hall devices in the linear magnetic field as a reference, and the variation is used as a nonlinear error;

when the voice coil motor moves, the nonlinear error is subtracted from the subtraction value of the magnetic field intensity sensed by the first Hall device and the second Hall device, and the correction of the magnetic field intensity sensed by the Hall assembly in the nonlinear magnetic field generated by the magnet is completed.

Technical Field

The invention relates to the technical field of voice coil motor control, in particular to a method for correcting nonlinearity of two ends of a magnetic field of a closed-loop voice coil motor by an extraction error method.

Background

With the increasing requirements for the camera quality of mobile phones, in recent years, more and more products adopt a voice coil motor for closed-loop control as a lens driving motor of a mobile phone camera.

In a closed-loop control voice coil motor, the position of the motor is determined by the magnitude of a hall sensor (hall sensor) induced magnetic field in a magnetic field. The motor can drive one device of the Hall and the magnet to move, and the other device of the Hall and the magnet can be fixed on the bracket; when the motor moves, the relative position of the Hall and the magnet can be changed, so that the size of a magnetic field sensed by the Hall is changed; the closed-loop control voice coil motor determines different positions of the motor according to different magnetic fields sensed by the Hall sensor.

Since the closed-loop control voice coil motor determines the position of the motor by sensing the magnitude of the magnetic field through the hall device, when there is nonlinearity between the magnitude and the position of the magnetic field, there will also be nonlinearity in the stroke of the motor position movement. The existence of non-linearity can affect the accuracy of the position of the voice coil motor, thereby affecting the focusing accuracy and further affecting the quality of the photographed image.

The magnet is composed of a magnetic south pole and a magnetic north pole, and the change trend of the magnetic field around the magnet is approximate to a sine curve in the process of moving from the magnetic south pole to the magnetic north pole. From the shape of the sinusoidal curve, the non-linearity of the curve becomes more and more pronounced moving from the middle to the two sides. To ensure good linearity of the closed-loop control voice coil motor movement, the middle portion of the sinusoid corresponding to the magnetic field strength is typically taken as the motor stroke.

This selection requires a compromise between linearity and maximum stroke, the greater the maximum stroke, the worse the linearity, and conversely, the better the linearity, the shorter the maximum stroke. Meanwhile, due to the characteristics of the sine curve, no matter how small the stroke is taken, nonlinearity is inevitably introduced.

Disclosure of Invention

In order to improve the problem of nonlinearity at two ends of the stroke of a closed-loop control voice coil motor, the invention provides a mode capable of correcting nonlinearity at two ends of a magnetic field, and the method compensates nonlinearity of the magnetic field sensed by a Hall sensor by extracting the nonlinearity error between the magnetic field and a position; the method can effectively correct the nonlinearity of the strokes of the two ends of the motor and improve the linearity of the motor stroke, thereby improving the photographing effect of the closed-loop voice coil motor.

In order to achieve the purpose, the invention is realized by the following technical scheme:

an apparatus for correcting nonlinearity of two ends of a magnetic field of a closed-loop voice coil motor by an extraction error method, comprising:

a magnet comprising a magnetic south pole and a magnetic north pole;

a voice coil motor having an output; and

a hall assembly positioned in the magnetic field generated by the magnet, comprising:

the first Hall device is used for sensing the magnetic field intensity of the position where the first Hall device is located; and

the second Hall device is arranged at a distance from the first Hall device and used for sensing the magnetic field intensity of the position where the second Hall device is located;

the first Hall device and the second Hall device are located on the same side of the magnet, the output end of the voice coil motor can drive the magnet or the Hall assembly to move, and in the moving process, the distance between the first Hall device and the second Hall device is always kept unchanged.

Optionally, the output end of the voice coil motor may drive the magnet or the hall assembly to move along a first direction; the first direction is parallel to a direction from the first hall device to the second hall device.

Optionally, the output end of the voice coil motor may drive the magnet or the hall element to move in the first section along the first direction; in an initial position where the voice coil motor is not activated, both end points of the first section are symmetrically disposed about a middle position of the magnet.

Optionally, the length of the first segment is 400 μm.

On the other hand, the invention also discloses a method for applying the device for correcting the nonlinearity of the two ends of the magnetic field of the closed-loop voice coil motor by the extraction error method, which comprises the following steps:

extracting a non-linear error of a magnetic field strength induced by the hall assembly in a magnetic field generated by the magnet;

and correcting the magnetic field intensity induced by the Hall assembly in the magnetic field generated by the magnet according to the extracted nonlinear error.

Optionally, extracting a non-linear error of a magnetic field strength induced by the hall assembly in the magnetic field generated by the magnet comprises:

acquiring a characteristic curve of an added value of the magnetic field intensity of the Hall assembly in a linear magnetic field;

acquiring a characteristic curve of an added value of the magnetic field intensity of the Hall assembly in a nonlinear magnetic field generated by the magnet;

and calculating to obtain the nonlinear error of the magnetic field intensity induced by the Hall assembly in the nonlinear magnetic field generated by the magnet according to the characteristic curve of the added value of the magnetic field intensity of the Hall assembly in the linear magnetic field and the characteristic curve of the added value of the magnetic field intensity of the Hall assembly in the nonlinear magnetic field generated by the magnet.

Optionally, obtaining a characteristic curve of an added value of the magnetic field strength of the hall assembly in the nonlinear magnetic field generated by the magnet comprises:

the position of the Hall assembly is controlled through the voice coil motor, so that the magnetic field intensity sensed by the first Hall assembly and the second Hall assembly when the Hall assembly is at different positions is obtained;

and adding the magnetic field strengths sensed by the first Hall assembly and the second Hall assembly when the Hall assemblies are at different positions to obtain a characteristic curve of the added value of the magnetic field strengths of the Hall assemblies in the nonlinear magnetic field generated by the magnet.

Optionally, extracting a non-linear error of a magnetic field strength induced by the hall assembly in the magnetic field generated by the magnet comprises:

acquiring a characteristic curve of a subtraction value of the magnetic field intensity of the Hall assembly in a linear magnetic field;

acquiring a characteristic curve of a subtraction value of the magnetic field intensity of the Hall assembly in a nonlinear magnetic field generated by the magnet;

and calculating to obtain the nonlinear error of the magnetic field intensity induced by the Hall assembly in the nonlinear magnetic field generated by the magnet according to the characteristic curve of the subtraction value of the magnetic field intensity of the Hall assembly in the linear magnetic field and the characteristic curve of the subtraction value of the magnetic field intensity of the Hall assembly in the nonlinear magnetic field generated by the magnet.

Optionally, obtaining a characteristic curve of a subtracted value of the magnetic field strength of the hall assembly in the nonlinear magnetic field generated by the magnet comprises:

the position of the Hall assembly is controlled through the voice coil motor, so that the magnetic field intensity sensed by the first Hall assembly and the second Hall assembly when the Hall assembly is at different positions is obtained;

and subtracting the magnetic field strengths sensed by the first Hall assembly and the second Hall assembly when the Hall assemblies are at different positions to obtain a characteristic curve of a subtraction value of the magnetic field strengths of the Hall assemblies in the nonlinear magnetic field generated by the magnet.

Optionally, the correcting the magnetic field strength induced by the hall element in the magnetic field generated by the magnet according to the extracted non-linear error comprises:

when the voice coil motor is in a nonlinear magnetic field, setting a magnetic field intensity subtraction value induced by the first Hall device and the second Hall device at an initial position as a magnetic field subtraction value induced by two Hall devices of the linear magnetic field;

when the voice coil motor moves, the change quantity of the subtraction value of the magnetic field intensity sensed by the first Hall device and the second Hall device is used as a nonlinear error;

when the voice coil motor moves, the nonlinear error is subtracted from the added value of the magnetic field strengths sensed by the first Hall device and the second Hall device, and the correction of the magnetic field strength sensed by the Hall assembly in the magnetic field generated by the magnet is completed.

Optionally, the correcting the magnetic field strength induced by the hall element in the magnetic field generated by the magnet according to the extracted non-linear error comprises:

when the voice coil motor is in a nonlinear magnetic field, setting the magnetic field intensity added value induced by the first Hall device and the second Hall device at the initial position as the magnetic field added value induced by the two Hall devices in the linear magnetic field;

when the voice coil motor moves, the variation of the added magnetic field intensity values sensed by the first Hall device and the second Hall device is obtained by taking the added magnetic field values sensed by the two Hall devices in the linear magnetic field as a reference, and the variation is used as a nonlinear error;

when the voice coil motor moves, the nonlinear error is subtracted from the magnetic field intensity subtraction value induced by the first Hall device and the second Hall device, the magnetic field intensity induced by the Hall assembly in the nonlinear magnetic field generated by the magnet is corrected, and the relation between the magnetic field with better linearity and the position is obtained.

Compared with the prior art, the invention has the following advantages:

the invention provides a method for nonlinear correction of a magnetic field of a Hall device, which can well correct the nonlinearity of two ends of the magnetic field, so that a motor has a good linear stroke, and further the photographing quality of a mobile phone camera can be improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention patent, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

FIG. 1A is a schematic diagram of a magnet and Hall assembly according to an embodiment of the present invention;

FIG. 1B is a graph of magnetic field strength around a magnet versus position in accordance with an embodiment of the present invention;

FIG. 2 is a plot of magnetic field strength versus position for a selected region of FIG. 1B;

FIG. 3 is a diagram illustrating a positional relationship between a first Hall device and a second Hall device in an embodiment of the present invention;

FIG. 4 is a graph of magnetic field strength versus position for an ideal linear magnetic field;

FIG. 5A is a characteristic curve of the added value of the magnetic field strength of the Hall element in an ideal linear magnetic field according to an embodiment of the present invention;

FIG. 5B is a graph illustrating a subtraction value of magnetic field strength of a Hall element in an ideal linear magnetic field according to an embodiment of the present invention;

FIG. 6A is a characteristic curve of the added value of the magnetic field strength of the Hall element in the nonlinear magnetic field generated by the magnet according to one embodiment of the present invention;

FIG. 6B is a characteristic curve of a subtracted value of magnetic field strength of a Hall element in a non-linear magnetic field generated by the magnet according to an embodiment of the present invention;

FIG. 7 is a graph of additive and subtractive non-linear error versus position in accordance with an embodiment of the present invention;

FIG. 8A is a graph of magnetic field strength versus position sensed by a single Hall device;

FIG. 8B is a graph of non-linear error in magnetic field strength versus position sensed by a single Hall device;

FIG. 9A is a graph of the relationship between the summed and corrected magnetic field strength and position sensed by the Hall element, in accordance with an embodiment of the present invention;

FIG. 9B is a graph illustrating the relationship between the nonlinear error and the position of the Hall device according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. It is to be noted that the drawings are in a very simplified form and are all used in a non-precise scale for the purpose of facilitating and distinctly aiding in the description of the embodiments of the present invention. To make the objects, features and advantages of the present invention comprehensible, reference is made to the accompanying drawings. It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the implementation conditions of the present invention, so that the present invention has no technical significance, and any structural modification, ratio relationship change or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

Referring to fig. 1B, fig. 1B is a graph showing a relationship between magnetic field strength around a magnet and a position in the present embodiment. Wherein the abscissa represents position (position) in μm and the ordinate represents magnetic field strength (magnetic) in mT.

It is noted that "around the magnet" refers to the section from the magnetic south pole of the magnet to the magnetic north pole of the magnet.

As can be seen from fig. 1B, in an ideal case, the relationship between the magnetic field intensity around the magnet and the position is approximated to a sinusoidal curve, and the linear characteristic of the curve becomes worse from the middle position of the sinusoidal curve (the middle position of the sinusoidal curve corresponds to the middle position of the magnet) to both ends.

Typically, the voice coil motor will select a section of the sinusoidal curve with good linearity at the middle position as the stroke of the motor movement, such as the section defined by two dashed lines perpendicular to the abscissa in fig. 1B. Fig. 2 is a graph of magnetic field strength versus position for a selected region of fig. 1B, and it can be seen from fig. 2 that due to the inherent nature of the sinusoidal curve, no matter how small a motor stroke is selected, a certain non-linear error is introduced.

The embodiment provides a device for correcting nonlinearity of two ends of a magnetic field of a closed-loop voice coil motor by an extraction error method, which comprises a magnet and a Hall assembly. The hall assembly is disposed in the nonlinear magnetic field generated by the magnet, and the positional relationship between the magnet and the hall assembly is shown in fig. 1A.

One of the magnet and the hall assembly is mounted on the output end of the voice coil motor, and the other is fixed on any one of the brackets (not shown in the drawing). After the voice coil motor is started, the output end of the voice coil motor can drive the magnet or the Hall assembly to move, so that the relative position of the magnet and the Hall assembly is changed.

In the present embodiment, the above-described holder is not particularly limited as long as the holder can function to fix the magnet or the hall element.

Referring to fig. 1A, the magnet in this embodiment is horizontally disposed, and "S" and "N" on the magnet respectively represent a magnetic south pole and a magnetic north pole of the magnet, and the middle position of the magnet is located at the middle of the magnetic south pole and the magnetic north pole.

Referring to fig. 1A, the Hall assembly includes a first Hall device (Hall L) and a second Hall device (Hall R) that are disposed at an interval, the first Hall device and the second Hall device are located on the same side of the magnet, and the first Hall device and the second Hall device are respectively used for sensing the magnetic field strength of the respective positions of the first Hall device and the second Hall device. Based on the driving of the voice coil motor, the first Hall device and the second Hall device move back and forth along a first direction (the first direction refers to the direction from the magnetic south pole to the magnetic north pole of the magnet) relative to the magnet, and the distance between the first Hall device and the second Hall device is kept unchanged during the movement. For simplicity of description, the first hall device and the second hall device are hereinafter referred to as hall assemblies, and when the hall assemblies are moved to any position, the first hall assembly and the second hall assembly are both symmetrically disposed about the position.

In this embodiment, the number of hall devices in the hall assembly and the relative position between the hall devices are not specifically limited, and the number of hall devices in the hall assembly is merely two, and the illustrated relative position between the hall devices is merely exemplified.

Referring to fig. 3, a position "0 μm" in fig. 3 indicates a middle position of the magnetic field, that is, a middle position of the first hall device and the second hall device in the initial position.

In this embodiment, the output end of the voice coil motor can drive the magnet or the hall element to move in the first section along the first direction; the two end points of the first section are symmetrically arranged about the middle position of the magnet.

In this embodiment, the length of the first segment is 400 μm. The length of the first segment is not particularly limited, and is exemplified by the length of the first segment being 400 μm.

Based on the same inventive concept, the present embodiment further provides a method for applying the apparatus for correcting nonlinearity at two ends of a magnetic field of a closed-loop voice coil motor by using the error extraction method, where the method includes:

s1, extracting the nonlinear error of the magnetic field intensity induced by the Hall assembly in the magnetic field generated by the magnet;

and S2, correcting the magnetic field intensity induced by the Hall assembly in the magnetic field generated by the magnet according to the extracted nonlinear error.

In this embodiment, extracting a non-linear error of a magnetic field strength induced by the hall element in the magnetic field generated by the magnet includes:

s101, acquiring a characteristic curve of an added value of the magnetic field intensity of the Hall assembly in an ideal linear magnetic field;

the field strength versus position of an ideal linear magnetic field is shown in fig. 4, with the abscissa representing position in μm and the ordinate representing field strength in mT;

referring to fig. 5A, it can be seen that when the magnetic field is linear, the characteristic curves of the added values of the magnetic field strength sensed by the first hall device and the second hall device versus the position are also linear.

S102, acquiring a characteristic curve of an added value of the magnetic field intensity of the Hall assembly in a nonlinear magnetic field generated by the magnet;

referring to fig. 6A, it can be seen that, when the magnetic field is non-linear, the characteristic curves of the added values of the magnetic field strength sensed by the first hall device and the second hall device and the position also have non-linearity.

And S103, subtracting the characteristic curve of the position and the added value of the magnetic field strength of the Hall assembly in the ideal linear magnetic field from the characteristic curve of the position and the added value of the magnetic field strength of the Hall assembly in the nonlinear magnetic field generated by the magnet in the FIG. 6A, and calculating to obtain the nonlinear error of the added value of the magnetic field strength induced by the Hall assembly in the nonlinear magnetic field generated by the magnet.

The method for acquiring the characteristic curve of the added value of the magnetic field intensity of the Hall assembly in the nonlinear magnetic field comprises the following steps:

s1011, controlling the position of the Hall assembly through the voice coil motor to obtain the magnetic field intensity sensed by the first Hall assembly and the second Hall assembly when the Hall assembly is at different positions;

and S1012, adding the magnetic field strengths sensed by the first Hall assembly and the second Hall assembly when the Hall assemblies are at different positions to obtain a characteristic curve of the added value of the magnetic field strengths of the Hall assemblies in the nonlinear magnetic field generated by the magnet and the positions.

In this embodiment, extracting a non-linear error of a magnetic field strength induced by the hall element in a magnetic field generated by the magnet further includes:

s111, acquiring a characteristic curve of a subtraction value of the magnetic field intensity of the Hall assembly in an ideal linear magnetic field;

the field strength versus position of an ideal linear magnetic field is shown in fig. 4, with the abscissa in μm and the ordinate in mT;

the "subtraction value" herein may refer to a magnetic field strength induced by the first hall device minus a magnetic field strength induced by the second hall device, or may refer to a magnetic field strength induced by the second hall device minus a magnetic field strength induced by the first hall device, which is not specifically limited in this embodiment.

Referring to fig. 5B, it can be seen that when the magnetic field is linear, the subtracted value of the magnetic field strength sensed by the first hall device and the subtracted value of the magnetic field strength sensed by the second hall device are kept constant, which is a characteristic of the subtracted value of the magnetic field strength sensed by two hall devices with fixed spacing in the linear magnetic field.

S112, acquiring a characteristic curve of a subtraction value of the magnetic field intensity of the Hall assembly in the nonlinear magnetic field generated by the magnet;

referring to fig. 6B, it can be seen that when the magnetic field is non-linear, the subtraction value of the magnetic field strength sensed by the first hall device and the second hall device varies with the non-linearity of the magnetic field.

S113, subtracting the characteristic curve of the subtraction value of the magnetic field strength of the hall element in fig. 5B in the ideal linear magnetic field from the characteristic curve of the subtraction value of the magnetic field strength of the hall element in fig. 6B in the nonlinear magnetic field generated by the magnet, and calculating to obtain the nonlinear error of the subtraction value of the magnetic field strength induced by the hall element in the nonlinear magnetic field generated by the magnet.

Wherein, the characteristic curve of the subtraction value of the magnetic field intensity of the Hall assembly in the nonlinear magnetic field generated by the magnet is obtained, and comprises the following steps:

s1111, controlling the position of the Hall assembly through the voice coil motor to acquire the magnetic field intensity sensed by the first Hall assembly and the second Hall assembly when the Hall assembly is at different positions;

and S1112, subtracting the magnetic field strengths sensed by the first Hall assembly and the second Hall assembly when the Hall assemblies are at different positions to obtain a characteristic curve of the subtraction value of the magnetic field strength of the Hall assemblies in the nonlinear magnetic field generated by the magnet and the position.

In this embodiment, the two calculated nonlinear errors (the nonlinear errors of the added value and the subtracted value) are shown in fig. 7, and two curves in fig. 7 represent the nonlinear error of the added value of the magnetic field strength sensed by the two hall devices and the nonlinear error of the subtracted value of the magnetic field strength sensed by the two hall devices, respectively, and the two curves are very close to each other. Because the coincidence degree of the two curves is high, after the voice coil motor is driven, one nonlinear error (the change quantity of the addition value or the subtraction value) can be used for correcting the corresponding other magnetic field strength value (the subtraction value or the addition value), and a good linear relation can be obtained. That is, the magnetic field strength of the added value may be corrected by the amount of change in the added value, or the magnetic field strength of the added value may be corrected by the amount of change in the subtracted value.

In this embodiment, the correcting the magnetic field strength induced by the hall element in the magnetic field generated by the magnet according to the extracted nonlinear error includes:

s201, when the voice coil motor is in a nonlinear magnetic field, setting magnetic field intensity subtraction values sensed by the first Hall device and the second Hall device at initial positions as magnetic field subtraction values sensed by the two Hall devices in the linear magnetic field;

s202, when the voice coil motor moves, taking a magnetic field subtraction value sensed by two Hall devices in a linear magnetic field as a reference, and acquiring a change quantity of the magnetic field subtraction value sensed by the first Hall device and the second Hall device, and taking the change quantity as a nonlinear error;

and S203, when the voice coil motor moves, subtracting the nonlinear error from the sum of the magnetic field strengths induced by the first Hall device and the second Hall device, completing the correction of the magnetic field strength induced by the Hall assembly in the nonlinear magnetic field generated by the magnet, and obtaining a relationship between the magnetic field with better linearity and the position.

In another embodiment, modifying the magnetic field strength induced by the hall element in the magnetic field generated by the magnet based on the extracted non-linearity error comprises:

s201, when the voice coil motor is in a nonlinear magnetic field, setting the added value of the magnetic field intensities induced by the first Hall device and the second Hall device at the initial position as the added value of the magnetic fields induced by the two Hall devices in the linear magnetic field;

s202, when the voice coil motor moves, taking a magnetic field addition value sensed by two Hall devices in a linear magnetic field as a reference, acquiring the variation of the magnetic field addition value sensed by the first Hall device and the second Hall device, and taking the variation as a nonlinear error;

and S203, when the voice coil motor moves, subtracting the nonlinear error from the subtraction value of the magnetic field intensity induced by the first Hall device and the second Hall device, finishing the correction of the magnetic field intensity induced by the Hall assembly in the nonlinear magnetic field generated by the magnet, and obtaining a relation between the magnetic field with better linearity and the position.

The relationship between the hall-induced magnetic field and the position obtained by the above-described correction method is shown in fig. 9A, in which the abscissa represents the unit μm of the position, and the ordinate represents the magnetic field intensity in unit mT after the two hall-induced magnetic fields are added and corrected.

The two curves in fig. 9A represent an ideal linear curve and an actual sensed curve, respectively, with the two curves substantially coinciding. Referring to fig. 9B, the abscissa in fig. 9B represents the position in μm, and the ordinate represents the nonlinear error after the sum is corrected, which is sensed by the two hall devices, in%.

As can be seen from fig. 9B, the maximum nonlinear error is about ± 0.7% at both ends of the magnetic field.

If the correction is not performed in the above manner, the obtained relationship graph of the magnetic field and the position is shown in fig. 8A, and fig. 8A shows the relationship between the magnetic field strength sensed by the hall device and the position when the single hall device is used for sensing the magnetic field strength.

As can be seen from fig. 8B, the non-linearity error is large at both ends of the magnetic field, reaching ± 3% or more.

As can be seen from fig. 8A, 8B, 9A, and 9B, the method for nonlinear correction of a magnetic field of a hall device according to this embodiment can well correct the nonlinearity at both ends of the magnetic field, so that a voice coil abuse object has a good linear stroke, and the photographing quality of a mobile phone camera can be improved.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.