TWI437795B - Voice coil motor - Google Patents

Description

Voice coil motor

The present invention relates to a voice coil motor, and more particularly to a voice coil motor that is miniaturized, has high positioning accuracy, low manufacturing cost, and low power consumption.

With the advancement of technology, cameras installed in mobile phones have been developed in the direction of high image quality, energy saving, low cost and miniaturization, and the actuators that drive the movement of the lens modules affect their products. Key components of quality.

At present, the automatic displacement driving device applied to the small lens module can be roughly divided into two according to the moving direction. The first automatic displacement driving device can provide rotational power, and the rotating axis thereof is parallel to the optical axis of the lens module, and the first Two automatic displacement drives provide translational power and are oriented parallel to the optical axis of the lens module.

The rotational motion of the first automatic displacement drive (eg, a stepper motor) typically requires an additional drive direction shifting mechanism to enable the lens module to move parallel to the optical axis. In the case of such an automatic displacement driving device, it is characterized in that when the lens module reaches the positioning, no additional power is required to maintain the position of the lens module. However, such an automatic displacement driving device has a very large number of constituent parts, and its construction complexity is relatively high, which is disadvantageous in reducing its volume and manufacturing cost.

Second automatic displacement drive (eg voice coil motor, piezoelectric actuation) The device and the liquid lens actuating device can directly apply force to the position adjustment, thereby eliminating the need for an additional transmission direction switching mechanism. Compared to the first automatic displacement drive, the second automatic displacement drive can have fewer components and a smaller volume. However, in the face of future market demand, how to reduce the size and cost of such automatic displacement driving device and improve its accuracy is an important issue.

Referring to Fig. 1, in a conventional lens driving device disclosed in U.S. Patent No. 6,856,469, the magnetic force of the magnetically permeable member 9, 10 and the radially magnetized mover magnet 6 is utilized to cause the coil 8 to be When energized, the mover magnet 6 of the movable member (including the lens 2) is attracted to the magnetic conductive members 9, 10, and is positioned and clamped together with the spring member 50, so that the movable member can be positioned at a specific position. (This is the open loop control mode). However, since the displacement amount due to the magnetic force change between the magnetic elements is nonlinear, the lens driving device has certain difficulty in the positioning control of the lens 2. Further, since the magnetic force between the magnetic conductive element 9 and the mover magnet 6 is very strong, a large current is required to balance the magnetic force, and thus it is more difficult to make the lens drive device energy-saving.

In addition, please refer to Fig. 2, in the voice coil motor device disclosed in the Republic of China Patent No. M305361, which is composed of four magnetic elements 45, 46, 47 (not shown in Fig. 2), 48 with two The magnetic conductive members 61, 62 are used for positioning the lens carrier 20 in multiple stages (this is also an open loop control mode). However, the lens mount 20 can only be fixed at a few specific positions (discontinuous).

In addition, please refer to Fig. 3, in Japanese Patent Publication No. 2005-128405 There is disclosed a conventional lens driving device 1. When the lens driving device 1 performs the auto focus operation, it can be divided into two focusing stages to explain the fixing and positioning mechanism of the movable member. First, when the lens driving device 1 is used to focus on a distant object, the moving portion thereof is abutted against one side of the fixing portion by the pre-pressure of the elastic pieces 9, 11, and the position of the moving portion is set to 0 mm. At this time, if the pre-pressure of the elastic pieces 9, 11 is larger than the weight of the moving part (assuming that the weight of the moving part is 960 mgw), the position of the moving part can be fixed even if the coil 15 of the lens driving device 1 is not supplied with current. At the position 0 mm, without changing with the posture, it is possible to achieve the lens driving device 1 for focusing on distant objects. On the other hand, when the lens driving device 1 is used for focusing on a near object, the moving portion thereof does not still abut against one side of the fixed portion, and the position of the moving portion is set to X mm (X>0). . At this time, the pre-pressure of the elastic pieces 9, 11 is more than 960 mgw, and the larger the X, the larger the pre-stress of the elastic pieces 9, 11. As described above, the coil 15 of the lens driving device 1 must be supplied with current, and the coil 15 and the permanent magnet 13 generate a force parallel to the moving direction of the moving portion in accordance with the principle of the electromagnetic voice coil. Then, by balancing the force with the pre-pressure of the elastic pieces 9, 11, the moving portion can be fixed at the position X mm without changing with the posture. Here, the current intensity of the coil 15 is at least such that the generated force is greater than 1920 mgw (i.e., the weight of the moving portion is doubled), and the larger the X, the current intensity of the coil 15 is The bigger it is. Therefore, the power consumption of the lens driving device 1 when positioning the moving portion can be quite large. In addition, the lens driving device 1 has the disadvantages that the elastic pieces 9, 11 are difficult to manufacture and the production cost is high. More specifically, by The elastic pieces 9 and 11 are easily deformed by the force, so that the design and the manufacturing difficulty of the lens driving device 1 are relatively high, which is disadvantageous for reducing the production cost.

The present invention basically employs the features detailed below in order to solve the above problems. That is, the present invention is applicable to autofocus of a lens module, and includes a fixing base; at least one guiding rod is connected to the fixing base; a coil is connected to the fixing base; and a magnetic conductive component is connected to the a mounting seat that is movably disposed over the guiding rod; and a magnetic member coupled to the mounting seat and corresponding to the magnetically conductive member along a direction of movement thereof, wherein the magnetic portion The magnetization direction of the component is parallel to the movement direction of the mounting seat and the magnetic component, the magnetic component has two opposite magnetic poles, one of the magnetic poles is surrounded by the coil, and the coil system interacts with the magnetic component to generate a voice coil force for driving the mount and the magnetic component relative to the mount, and the magnetic component interacting with the magnetic component to generate a magnetic force for assisting in positioning the mount and the Magnetic component.

Meanwhile, according to the voice coil motor of the present invention, the guide rod is made of a non-magnetic material.

In the present invention, a position sensor is further included, which is coupled to the fixing base and is opposite to the magnetic component for sensing the movement of the magnetic component.

Also in the present invention, the position sensor is a magnetic sensing element.

Also in the present invention, the magnetic sensing element comprises a Hall element.

In still another aspect of the invention, the magnetic sensing element includes a magnetoresistive sensing element.

In the present invention, the position sensor is a light sensing element.

In still another aspect of the invention, the light sensing element comprises a photointerrupter.

Also in the present invention, the position sensor includes an inductance measuring element.

The above described objects, features and advantages of the present invention will become more apparent from the description of the appended claims.

The preferred embodiment of the invention is described in conjunction with the drawings.

Referring to FIG. 4 and FIG. 5 , the voice coil motor 100 of the present embodiment can be applied to drive a lens module of a camera to perform auto focus, and mainly includes a fixing base 110 , two guiding rods 120 , and a coil 130 . A magnetic conductive component 140, a position sensor 150, a circuit board 160, a mounting base 170 and a magnetic component 180. Here, the fixing base 110, the guiding rod 120, the coil 130, the magnetic conductive element 140, the position sensor 150 and the circuit board 160 can be regarded as fixed parts of the voice coil motor 100, and the mounting seat 170 and the magnetic element 180 can be regarded as sound. The moving parts of the ring motor 100.

Both guiding rods 120 are connected to the fixing base 110. Here, both guiding rods 120 are made of a non-magnetic material.

The coil 130 is connected to the fixing base 110.

The magnetically conductive element 140 is coupled to the mount 110. More specifically, as shown in FIGS. 6 and 7, the magnetic conductive element 140 is fixed to one of the bottom faces 111 of the mount 110. In addition, although the magnetic conductive element 140 of the embodiment has There is a ring structure, but it is not limited to this. In other words, the magnetically permeable element 140 can also have a rectangular or other shape configuration depending on the actual application requirements.

As shown in FIGS. 4, 5, 6, and 7, the position sensor 150 is coupled to the mount 110. In this embodiment, the position sensor 150 can be a magnetic sensing component, a light sensing component, or an electrical sensing component. When the position sensor 150 is a magnetic sensing element, it can include a Hall element or a magnetoresistive sensing element. When position sensor 150 is a light sensing element, it can include a photointerrupter.

The circuit board 160 is also connected to the fixed base 110, and the circuit board 160 is electrically connected to the position sensor 150 and a positioning controller (not shown).

The mounting seat 170 is disposed on the two guiding rods 120 in a moving manner. In more detail, as shown in FIG. 4, the mounting seat 170 has a plurality of through holes 171, and the two guiding rods 120 are respectively disposed in the plurality of through holes 171. That is to say, the mounting seat 170 is disposed on the two guiding rods 120 by a plurality of through holes 171 thereof. In addition, the mount 170 can be used to mount or carry a lens module L (as shown in Figures 5, 6, and 7).

As shown in FIGS. 6 and 7, the magnetic member 180 is coupled to the mount 170, and the magnetic member 180 corresponds to the magnetic conductive member 140 along its moving direction. In the present embodiment, the magnetic element 180 has an annular configuration, and the magnetization direction of the magnetic element 180 is parallel to the direction of movement of the mount 170 and the magnetic element 180 (ie, the magnetic element 180 is axially charged). magnetic). In addition, the magnetic element 180 has two opposing magnetic poles 181, 182, and the magnetic pole 181 is surrounded by the coil 130 (ie, the magnetic pole 181 is located at the coil 130). The radially inner side), while the magnetic pole 182 is not surrounded by the coil 130 (i.e., the magnetic pole 182 is located axially outside the coil 130). In more detail, as shown in Fig. 7, the bottom of the coil 130 is spaced apart from the bottom of the magnetic element 180 by a distance δ, such that the magnetic pole 181 (e.g., N pole) is located radially inward of the coil 130 and the magnetic pole 182 (e.g. The S pole is located on the axial outer side of the coil 130. Therefore, the magnetic flux path of the magnetic element 180 passes through the coil 130 vertically through the arrangement of the coil 130 and the magnetic element 180. Further, the magnetic member 180 is not limited to a configuration having a ring shape. In other words, the magnetic element 180 can also have other configurations depending on the actual application requirements (eg, the shape of the magnetic conductive element 140).

As described above, when the coil 130 is energized, according to the principle of the electromagnetic voice coil, the coil 130 interacts with the magnetic element 180 to generate a voice coil force F ₁ , and the voice coil force F ₁ can drive the installation. The seat 170 and the magnetic element 180 move relative to the mount 110 (or along one of the optical axes of the lens module L).

In another aspect, the magnetic element 180 will interact with the magnetic member 140 generates a magnetic attractive force F _2, which may be used to assist in positioning the mount 170 and the magnetic element 180 (this part into the operating mode will be described in the following description) .

In addition, in order to improve the positioning accuracy, the function of the closed loop positioning control can be achieved by combining the position sensor 150, the circuit board 160 and the positioning controller in the voice coil motor 100. For example, when the position sensor 150 is a Hall element or a magnetoresistive sensing element in a magnetic sensing element, the Hall element or the magnetoresistive sensing element senses a fixed point in the voice coil motor 100. The (leakage) magnetic field strength of the magnetic element 180. Here, the magnetic point at a certain fixed point The (drain) magnetic field strength of element 180 has a certain relationship with the displacement of magnetic element 180. Therefore, by combining the position sensor 150 and the positioning controller, the closed loop positioning control can be performed, thereby controlling the movement position of the mount 170 and the magnetic member 180 (or the relative relationship between the mount 170 and the mount 110). position). Since the above method of closed loop positioning control is a conventional technique, it will not be described here.

When the voice coil motor 100 is applied to the auto focusing of the lens module L, it can be divided into two focusing stages to explain the fixing and positioning mechanism of the moving parts (the mount 170 and the magnetic element 180).

First, when the voice coil motor 100 is used to focus on a distant object, the mount 170 carrying the lens module L is abutted against the mount 110 as shown in FIG. Meanwhile, as shown in Fig. 8, the distance between the magnetic conductive member 140 and the magnetic member 180 is δ ₀ . Here, the position of the moving member at this time can be set to 0 mm. It is to be noted that, assuming that the magnetic attraction force F ₂ between the magnetic conductive member 140 and the magnetic member 180 is just greater than the weight of the moving member (assuming 960 mgw), the moving member can be used even if the coil 130 is not energized. It is fixed at the position 0 mm without changing with the posture of the voice coil motor 100. As described above, when the voice coil motor 100 is used to focus on a distant object, the coil 130 can be operated without an electric current, and thus the power saving effect can be achieved.

Then, when the voice coil motor 100 is used to focus on a near object, the mount 170 carrying the lens module L does not abut against the mount 110. At this time, as shown in Fig. 9, the distance between the magnetic conductive element 140 and the magnetic element 180 is δ ₁ and δ ₁ > δ ₀ . Here, as shown in Fig. 9, the position of the moving member at this time can be set to X mm, and X = δ ₁ - δ ₀ > Notably, when the magnetic attractive force F between the magnetic member 180 and magnetic member 140 will be less than ₂ 960mgw (X because the greater the magnetic attraction between the magnetic elements 180 and 140 will be smaller magnetic element ₂ F This is a conventional physical principle. As a result, the coil 130 must be energized, and the coil 130 and the magnetic element 180 generate a voice coil force F ₁ due to the principle of the electromagnetic voice coil. Through the closed loop positioning control described above, the moving member can be positioned at the position X mm, and the positioning position of the moving member does not change with the posture of the voice coil motor 100. It is worth noting that the current intensity of the coil 130 is maximized so that the voice coil force F _{1 is} greater than 1920 mgw (i.e., the weight of the moving parts is doubled). Here, the current intensity of the coil 130 is reduced as X increases. As described above, when the voice coil motor 100 is used to focus on a near object, the current intensity of the coil 130 is reduced as the moving distance of the moving member increases, and thus the power saving effect can be achieved.

In summary, the voice coil motor disclosed in the present invention performs continuous positioning and clamping operations on its moving parts by an innovative magnetic circuit structure and closed loop positioning control, thereby achieving the purpose of saving power consumption.

Although the present invention has been disclosed in its preferred embodiments, it is not intended to limit the present invention, and it is possible to make some modifications and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

1‧‧‧Lens driver

2‧‧‧Lens module

6‧‧‧ mover magnet

8, 15‧‧‧ coil

9‧‧‧Magnetic elements, shrapnel

10‧‧‧Magnetic components

11‧‧‧Shrap

13‧‧‧ permanent magnet

20‧‧‧Lens carrier

45, 46, 47, 48‧‧‧ magnetic components

50‧‧‧Spring elements

61, 62‧‧‧ magnetically conductive parts

100‧‧‧ voice coil motor

110‧‧‧ fixed seat

111‧‧‧ bottom

120‧‧‧ Guide rod

130‧‧‧ coil

140‧‧‧Magnetic components

150‧‧‧ position sensor

160‧‧‧ boards

170‧‧‧ Mounting

171‧‧‧through hole

180‧‧‧Magnetic components

181, 182‧‧ ‧ magnetic pole

F ₁ ‧‧‧ voice coil force

F ₂ ‧‧‧Magnetic attraction

L‧‧‧ lens module

δ, δ ₀ , δ ₁ ‧‧‧ distance

1 is a perspective view showing a part of a conventional lens driving device; FIG. 2 is a perspective exploded view showing a conventional voice coil motor device; and FIG. 3 is a schematic cross-sectional view showing another conventional lens driving device; 4 is a perspective exploded view showing the voice coil motor of the present invention; FIG. 5 is a perspective view showing a three-dimensional combination of the voice coil motor and a lens module of the present invention; and FIG. 6 is a perspective sectional view showing the same according to FIG. 5; Figure 7 is a schematic cross-sectional view showing a portion of the voice coil motor of the present invention; and Figure 9 is a cross-sectional view showing a portion of the voice coil motor of the present invention; and Figure 9 is a view showing another portion of the voice coil motor of the present invention. Schematic diagram of the structure.

110‧‧‧ fixed seat

111‧‧‧ bottom

120‧‧‧ Guide rod

130‧‧‧ coil

140‧‧‧Magnetic components

150‧‧‧ position sensor

160‧‧‧ boards

170‧‧‧ Mounting

180‧‧‧Magnetic components

181, 182‧‧ ‧ magnetic pole

L‧‧‧ lens module

Claims (9)

A voice coil motor includes: a fixing base; at least one guiding rod connected to the fixing base, wherein the guiding rod is made of a non-magnetic material; a coil is connected to the fixing seat; a magnetic component connected to the fixing base; a mounting seat disposed on the guiding rod in a moving manner; and a magnetic component coupled to the mounting seat and corresponding to the magnetic conductive direction along a moving direction thereof An element, wherein the magnetic element interacts with the magnetically conductive element to generate a magnetic attraction for assisting in positioning the mount and the magnetic element. The voice coil motor of claim 1, further comprising a position sensor coupled to the mount and configured to sense movement of the magnetic member relative to the magnetic member. The voice coil motor of claim 2, wherein the position sensor is a magnetic sensing element. The voice coil motor of claim 3, wherein the magnetic sensing element comprises a Hall element. The voice coil motor of claim 3, wherein the magnetic sensing component comprises a magnetoresistive sensing component. The voice coil motor of claim 2, wherein the position sensor is a light sensing element. The voice coil motor of claim 6, wherein the light sensing element comprises a photointerrupter. The voice coil motor of claim 2, wherein the position sensor is an electrical sensing component. The voice coil motor of claim 1, wherein the magnetic component has a magnetization direction parallel to the mounting seat and the moving direction of the magnetic component, the magnetic component having two opposing magnetic poles, one of the magnetic poles Surrounded by the coil, and the coil system interacts with the magnetic element to generate a voice coil force for driving the mount and the magnetic element relative to the mount.