阅读说明：本技术 一种修正闭环音圈马达磁铁零磁区非线性的方法 (Method for correcting nonlinearity of zero magnetic area of closed-loop voice coil motor magnet ) 是由 陈珍珍 陈君飞 张洪 于 2021-08-26 设计创作，主要内容包括：本发明公开了一种修正闭环音圈马达磁铁零磁区非线性的方法,该方法包含：设置霍尔组件,所述霍尔组件具有一定长度,所述霍尔组件的两端关于磁场中心对称；闭环音圈马达移动时,所述霍尔组件跟随所述闭环音圈马达同步移动；采用所述霍尔组件感应所述闭环音圈马达移动时磁场的变化,当所述闭环音圈马达向正方向移动和负方向移动时,采用处于线性区段的所述霍尔组件感应的磁场作为马达位置信号。其优点是：该方法通过设置两端关于磁场中心对称的霍尔组件,当闭环音圈马达移动时,采用处于线性区段的所述霍尔组件感应的磁场作为马达位置信号,从而使得整个行程中马达位置的线性度更好,提升闭环音圈马达的拍照效果。(The invention discloses a method for correcting the nonlinearity of a zero magnetic area of a closed-loop voice coil motor magnet, which comprises the following steps: arranging a Hall assembly, wherein the Hall assembly has a certain length, and two ends of the Hall assembly are symmetrical about the center of a magnetic field; when the closed-loop voice coil motor moves, the Hall assembly moves synchronously along with the closed-loop voice coil motor; adopt hall subassembly response the change in magnetic field when closed loop voice coil motor removes, when closed loop voice coil motor moves to the positive direction and when the negative direction removes, adopt to be in linear section the magnetic field of hall subassembly response is as motor position signal. The advantages are that: according to the method, the Hall assemblies with two ends symmetrical about the center of the magnetic field are arranged, when the closed-loop voice coil motor moves, the magnetic field induced by the Hall assemblies in the linear section is used as a motor position signal, so that the linearity of the position of the motor in the whole stroke is better, and the photographing effect of the closed-loop voice coil motor is improved.)

1. A method for correcting a zero field nonlinearity of a closed-loop voice coil motor magnet, comprising:

the method comprises the following steps of arranging a Hall assembly, wherein the Hall assembly has a certain length, and the length of the Hall assembly is greater than the length of a zero magnetic area range of a magnetic field;

when the closed-loop voice coil motor moves, the Hall assembly moves synchronously along with the closed-loop voice coil motor;

adopt hall subassembly response the change in magnetic field when closed loop voice coil motor removes, when closed loop voice coil motor moves to the positive direction and when the negative direction removes, adopt to be in linear section the magnetic field of hall subassembly response is as motor position signal.

2. The method of correcting for closed loop voice coil motor magnet null non-linearity of claim 1,

the Hall assembly is a first Hall device, and the first Hall device has a certain length.

3. The method of correcting for closed loop voice coil motor magnet null non-linearity of claim 2,

the first Hall device has a length of 10 μm or 25 μm or 50 μm or 100 μm or 200 μm or 300 μm or 500 μm.

4. The method of correcting for closed loop voice coil motor magnet null nonlinearity of claim 1, wherein said hall element comprises:

the second Hall device and the third Hall device are symmetrically arranged relative to the center of the magnetic field, and the moving speeds of the second Hall device and the third Hall device are the same.

5. The method of correcting for closed loop voice coil motor magnet null non-linearity of claim 4,

the distance between the second Hall device and the third Hall device is adjustable.

6. The method of correcting for closed loop voice coil motor magnet null field nonlinearity of claim 4 or claim 5,

the distance between the second Hall device and the third Hall device is 10 μm or 25 μm or 50 μm or 100 μm or 200 μm or 300 μm or 500 μm.

Technical Field

The invention relates to the technical field of voice coil motor control, in particular to a method for correcting the nonlinearity of a zero magnetic area of a closed-loop voice coil motor magnet.

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 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 the size of the magnetic field induced by the hall device, when the nonlinearity exists between the size and the position of the magnetic field, the nonlinearity also exists in the stroke of the position movement of the motor. 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.

Magnets are usually made up of a magnetic south pole (S pole) and a magnetic north pole (N pole), and when the magnet is manufactured, there is often a null magnetic region between the magnetic south pole and the magnetic north pole, which is neither a south pole nor a north pole. The existence of the zero magnetic region can cause the linearity of the magnetic field strength around the magnet in relation to the position in the vicinity of the zero magnetic region, namely, the nonlinearity of the position-magnetic field strength relation occurs, and the nonlinearity can cause the nonlinearity of the stroke of the voice coil motor.

Disclosure of Invention

The invention aims to provide a method for correcting the nonlinearity of a zero magnetic area of a closed-loop voice coil motor magnet, which comprises the steps that a Hall assembly with two ends symmetrical about the center of a magnetic field is arranged, and when the closed-loop voice coil motor moves, the Hall assembly moves synchronously along with the closed-loop voice coil motor; adopt hall subassembly response the change in magnetic field when closed loop voice coil motor removes, when closed loop voice coil motor moves to the positive direction and when the negative direction removes, adopt to be in linear section the magnetic field of hall subassembly response is as motor position signal. In whole removal in-process, the magnetic field that the hall subassembly of inductive position was located all has better linearity to make the linearity of motor position better in the whole stroke, promote the effect of shooing of closed loop voice coil motor.

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

a method for correcting a zero field nonlinearity of a closed-loop voice coil motor magnet, comprising:

the method comprises the following steps of arranging a Hall assembly, wherein the Hall assembly has a certain length, and the length of the Hall assembly is greater than the length of a zero magnetic area range of a magnetic field;

when the closed-loop voice coil motor moves, the Hall assembly moves synchronously along with the closed-loop voice coil motor;

adopt hall subassembly response the change in magnetic field when closed loop voice coil motor removes, when closed loop voice coil motor moves to the positive direction and when the negative direction removes, adopt to be in linear section the magnetic field of hall subassembly response is as motor position signal.

Optionally, the hall assembly is a first hall device, and the first hall device has a certain length.

Optionally, the length of the first hall device is 10 μm or 25 μm or 50 μm or 100 μm or 200 μm or 300 μm or 500 μm.

Optionally, the hall element includes:

the second Hall device and the third Hall device are symmetrically arranged relative to the center of the magnetic field, and the moving speeds of the second Hall device and the third Hall device are the same.

Optionally, a distance between the second hall device and the third hall device is adjustable.

Optionally, a distance between the second hall device and the third hall device is 10 μm or 25 μm or 50 μm or 100 μm or 200 μm or 300 μm or 500 μm.

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

according to the method for correcting the nonlinearity of the zero magnetic area of the closed-loop voice coil motor magnet, the Hall assembly with two ends symmetrical about the center of a magnetic field is arranged, and when the closed-loop voice coil motor moves, the Hall assembly moves synchronously along with the closed-loop voice coil motor; adopt hall subassembly response the change in magnetic field when closed loop voice coil motor removes, when closed loop voice coil motor moves to the positive direction and when the negative direction removes, adopt to be in linear section the magnetic field of hall subassembly response is as motor position signal. During the whole moving process, the magnetic field of the Hall assembly at the induction position has better linearity, so that the linearity of the position of the motor in the whole stroke is better.

Furthermore, in the method for correcting the nonlinearity of the zero magnetic area of the closed-loop voice coil motor magnet, the Hall assembly is a single Hall device (a first Hall device) or two Hall devices (a second Hall device and a third Hall device) are combined, so that the nonlinearity of the stroke of the voice coil motor caused by the zero magnetic area of the magnet can be effectively corrected, the stroke linearity of the motor is improved, and the photographing effect of the closed-loop voice coil motor is further improved.

Drawings

FIG. 1 is a schematic diagram of a method for correcting the zero field nonlinearity of a closed-loop voice coil motor magnet according to the present invention;

FIG. 2 is a schematic diagram showing the relationship between the magnetic field strength around the magnet and the position under ideal conditions provided by the embodiment of the present invention;

FIG. 3 is a schematic diagram showing the relationship between the magnetic field strength around the magnet and the position in the practical case in the theory provided by the embodiment of the present invention;

FIG. 4 is a schematic diagram of the relationship between the magnetic field strength around the magnet and the position under actual test provided by the embodiment of the present invention;

FIG. 5 is a schematic diagram illustrating an approximate relationship between magnetic field strength and position in a selected magnet middle region according to an embodiment of the present invention;

FIG. 6 is a schematic diagram illustrating a position of a Hall assembly in a magnetic field according to an embodiment of the present invention;

FIG. 7 illustrates a Hall device that is small enough to sense the relationship between magnetic field and position provided by embodiments of the present invention;

fig. 8 is a relationship between equivalent magnetic fields and positions sensed by the first hall devices of respective lengths according to an embodiment of the present invention;

fig. 9 is a relationship between the equivalent magnetic field nonlinearity sensed by the first hall device of each length and the length of the hall device according to the embodiment of the present invention;

fig. 10 is a diagram illustrating a relationship between equivalent magnetic fields induced by different distances between hall devices and positions according to an embodiment of the present invention;

fig. 11 is a diagram illustrating a relationship between equivalent magnetic field nonlinearity induced by different hall device spacings and hall device spacings according to an embodiment of the present invention.

Detailed Description

The present invention will now be further described by way of the following detailed description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings.

The following describes a method for correcting nonlinearity of two ends of a magnetic field of a closed-loop voice coil motor according to the present invention in further detail with reference to the accompanying drawings and the following detailed description. The advantages and features of the present invention will become more apparent from the following description. 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.

As shown in fig. 1, a method for correcting the zero field nonlinearity of a closed-loop vcm magnet according to the present invention includes: the method comprises the following steps that a Hall assembly is arranged, the Hall assembly has a certain length, and the length is larger than the zero magnetic area position of a magnetic field, namely the length of the Hall assembly is larger than the zero magnetic area range length of the magnetic field, so that one end of the Hall assembly is always in a linear section when a motor moves; when the closed-loop voice coil motor moves, the Hall assembly moves synchronously along with the closed-loop voice coil motor; adopt hall subassembly response the change in magnetic field when closed loop voice coil motor removes, when closed loop voice coil motor moves to the positive direction and when the negative direction removes, adopt to be in linear section the magnetic field of hall subassembly response is as motor position signal.

As shown in fig. 2, the relationship between the magnetic field strength around the magnet and the position is ideal. The rectangles in FIG. 2 represent magnets, N represents magnetic north poles, and S represents magnetic south poles; the lower curve of fig. 2 shows the correspondence between the position around the magnet and the magnetic field strength, where the abscissa shows the position and the ordinate shows the magnetic field strength.

Specifically, as shown in fig. 2, ideally, the magnetic field around the magnet is approximately sinusoidal (sine wave) from the position. In general, a voice coil motor (abbreviated as a motor) with closed-loop control takes a part of a region with good linearity in the middle of a sine curve as a stroke of the motor movement, for example, a region defined by two dotted lines perpendicular to an abscissa in fig. 2, so as to ensure good linearity of the motor stroke.

In practice, however, there will be a null between the magnetic south and north poles of the magnet, the presence of which will cause poor linearity at the mid-position of the magnet, as shown in fig. 3.

The rectangles in FIG. 3 represent magnets, N represents magnetic north poles, and S represents magnetic south poles; the lower curve of fig. 3 shows the correspondence between the position around the magnet and the magnetic field strength, where the abscissa shows the position and the ordinate shows the magnetic field strength.

As can be seen from fig. 3, there is a distance near the location where the magnetic south pole and the magnetic north pole of the magnet are connected, where the magnetic field strength varies little with location, and the magnetic field strength does not match the magnetic field strength of other areas near the location by a factor of the change in position, i.e., there is a non-linearity between the magnetic field strength and the location in the area.

The nonlinearity of the area can cause nonlinearity between an actual position and an input target position when the motor moves, namely the nonlinearity occurs in the motor stroke; this non-linearity can affect the accuracy of the motor's movement position, affect the accuracy of the focus, and thus affect the image quality.

As shown in fig. 4, the relationship between the magnetic field strength and the hall position obtained for the actual motor test is shown. In fig. 4, the abscissa represents the hall position and the ordinate represents the magnetic field strength. As can be seen from fig. 4, at the intermediate position, there is a non-linearity in the magnetic field strength as a function of position. To study the field non-linearity near the null region of the magnet in fig. 3 and 4, the middle field curve of the magnet was taken and is approximated by fig. 5. In fig. 5, the abscissa indicates the position around the magnet in μm, and the ordinate indicates the magnetic field strength at the corresponding position in mT. As can be seen from FIG. 5, between-50 μm and 50 μm, there is a non-linearity between the magnetic field and the position, and everywhere else is a linearity between the magnetic field and the position.

When the Hall and the magnet move relatively, the magnetic fields sensed by the Hall correspond to the positions of the Hall, and the nonlinearity of the magnetic fields is completely reflected, so that the strokes of the motors show the same nonlinearity.

In a closed-loop control voice coil motor, in order to provide a good linearity of the motor stroke while having a large stroke, the motor is generally bi-directional and can move from the middle to both sides.

If the Hall sensor is always in the linear region of the magnetic field or the region with better linearity of the magnetic field and cannot move to the region with poor linearity at the two ends of the magnetic field in the moving process of the motor, the magnetic field induced by the Hall sensor is linear with the position, so that the motor is ensured to have better linear stroke.

In the present invention, as shown in fig. 6, a hall element is provided to sense the change in magnetic field as the closed loop voice coil motor moves. Specifically, the middle position in fig. 6 corresponds to the middle position of the magnetic field, the hall element has a certain length, and both ends of the hall element are symmetrical with respect to the center of the magnetic field.

When the closed-loop voice coil motor moves, the Hall assembly moves synchronously along with the closed-loop voice coil motor. Adopt hall subassembly response the change in magnetic field when closed loop voice coil motor removes, when closed loop voice coil motor moves to the positive direction and when the negative direction removes, adopt to be in linear section the magnetic field of hall subassembly response is as motor position signal. In the whole moving process, the magnetic field of the Hall device at the induction position has better linearity, so that the linearity of the position of the motor in the whole stroke is better.

In this embodiment, the hall assembly is a first hall device, and is a single hall system, and the first hall device has a certain length.

In a single hall system, because the first hall device has a size, in a magnetic field that varies with position, the magnetic field strengths sensed at different places of the first hall device are different, so the final output voltage of the first hall device should be the average of all the magnetic fields sensed on the first hall device, and the average magnetic field can be regarded as the magnetic field strengths at different positions on the first hall device are integrated and then divided by the whole area of the first hall device.

When the area of the first hall device is small enough to be considered as a point, the relationship of the induced magnetic field to the position is as shown in fig. 7. The light black line in fig. 7 indicates the magnitude of the magnetic field to which the point hall device is moved at a position of ± 200 μm, where the abscissa indicates the position in μm and the ordinate indicates the magnetic field induced by the hall in mT. As can be seen from comparing fig. 7 and 5, when the hall device area is sufficiently small, the hall device can completely reflect the characteristics of the magnetic field. When the hall has a certain size, the equivalent magnetic field above the hall is the average of the magnetic field sensed on the whole hall surface, so the magnetic field has an average effect. Therefore, the magnetic field induced by the first Hall device with a certain length and size has better linearity, so that the linearity of the position of the motor in the whole stroke is better.

Optionally, the length of the first hall device is 10 μm or 25 μm or 50 μm or 100 μm or 200 μm or 300 μm or 500 μm. Illustratively, moving the first hall device within a range of ± 200 μm simulates the relationship between the equivalent magnetic field and the position sensed by the first hall device of each length as shown in fig. 8. The 0 μm position here is the alignment of the first hall device midpoint with the magnetic field midpoint.

In fig. 8, the abscissa indicates the position of the first hall device, and the ordinate indicates the equivalent magnetic field induced by the first hall device. As can be seen from fig. 8, as the size of the first hall device increases, the nonlinearity of the equivalent magnetic field sensed by the first hall device gradually decreases.

FIG. 9 is a graph illustrating the maximum non-linear error of the sensed magnetic field when the first Hall devices of different sizes are moved at the + -200 μm position. The abscissa in fig. 9 represents the size of the first hall device, and the ordinate represents the nonlinearity of the induced magnetic field.

As can also be seen from fig. 9, as the size of the first hall device increases, the non-linear error of the magnetic field sensed by the first hall device gradually decreases; when the size of the first Hall device is increased to 500 μm, the non-linear error of the induced magnetic field is reduced to zero.

From the foregoing, increasing the size of the first hall device can reduce the non-linearity of the magnetic field at the null region of the magnetic field. In actual work, the size of the first Hall device can be selected to be suitable for application according to needs and actual application scenes.

In another embodiment, on the other hand, the hall assembly comprises a second hall device and a third hall device. The second Hall device and the third Hall device are symmetrically arranged around the center of the magnetic field, and the moving speeds of the second Hall device and the third Hall device are the same.

The magnetic field induced by the two Hall devices is equivalent to the magnetic field induced by a large-area Hall device, and the size of the applied Hall device can be effectively reduced by the method, so that the area consumed by correcting the nonlinearity of the zero magnetic area is reduced. Specifically, when two hall devices are used to sense the magnetic field, an equivalent magnetic field strength can be obtained after the magnetic fields sensed by the two hall devices are summed and averaged.

Further, the distance between the second Hall device and the third Hall device is adjustable. In practical application, the size of the magnetic field where the two Hall devices are located at the same time can be changed by changing the distance between the two Hall devices, so that the characteristics of the induced equivalent magnetic field are changed.

For example, when the distances between the second hall device and the third hall device are set to 10 μm, 25 μm, 50 μm, 100 μm, 200 μm, 300 μm, and 500 μm, respectively, the two hall devices are moved within ± 200 μm, and it can be simulated that the equivalent magnetic fields induced by the two hall devices are as shown in fig. 10. The 0 μm position here is the alignment of the midpoints of the two hall devices with the midpoint of the magnetic field.

In fig. 10, the abscissa represents the moving position of the hall device in μm, and the ordinate represents the equivalent magnetic field sensed by the hall device in mT.

As can be seen from fig. 10, when the distance between the second hall device and the third hall device is small, the equivalent magnetic field induced at the middle position of the zero magnetic area has nonlinearity; along with the gradual increase of the distance between the two Hall devices, the nonlinearity at the middle position is gradually improved; when the distance between the two Hall devices is increased to a certain position, the nonlinearity of the magnetic field at the middle position of the zero magnetic area disappears, and the nonlinearity of the equivalent magnetic field induced at the two side positions exists. Further, as can be seen from fig. 10, as the size between the two hall devices gradually increases, the nonlinearity of the equivalent magnetic field induced between the two hall devices gradually decreases.

As shown in fig. 11, the magnitude of the nonlinear error in sensing the equivalent magnetic field when the distances between the two hall devices are different is counted. As can be seen from fig. 11, as the distance between the two hall devices increases, the overall tendency of the induced equivalent magnetic field to be nonlinear decreases; when the distance between the two hall devices is 500 μm, the equivalent magnetic field nonlinearity induced by the hall element decreases to 0.

Therefore, the Hall assembly can also correct the nonlinearity of the magnetic field in the zero magnetic area by adopting the two Hall devices, and the nonlinearity of the magnetic field in the zero magnetic area can be reduced to an ideal value by reasonably designing the distance between the two Hall devices; when the distance between the two Hall devices is pulled, circuits which do not influence the Hall performance can be placed in the space between the two Hall devices, so that the area is fully utilized.

In summary, in the method for correcting the nonlinearity of the zero magnetic area of the closed-loop voice coil motor magnet, the hall assemblies with two ends symmetrical with respect to the center of the magnetic field are arranged, and when the closed-loop voice coil motor moves, the hall assemblies move synchronously along with the closed-loop voice coil motor; adopt hall subassembly response the change in magnetic field when closed loop voice coil motor removes, when closed loop voice coil motor moves to the positive direction and when the negative direction removes, adopt to be in linear section the magnetic field of hall subassembly response is as motor position signal. During the whole moving process, the magnetic field of the Hall assembly at the induction position has better linearity, so that the linearity of the position of the motor in the whole stroke is better.

Furthermore, in the method for correcting the nonlinearity of the zero magnetic area of the closed-loop voice coil motor magnet, the Hall assembly is a single Hall device (a first Hall device) or a mode of combining two Hall devices (a second Hall device and a third Hall device), so that the nonlinearity of the stroke of the voice coil motor caused by the zero magnetic area of the magnet can be effectively corrected, the stroke linearity of the motor is improved, and the photographing effect of the closed-loop voice coil motor is further improved.

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. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

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.