TW201905567A - Closed loop lens driver - Google Patents

Abstract

A closed-loop lens driving device includes a base, a lens holder used for holding a lens, a coil winding around an outer periphery of the lens holder, plural magnets configured at an outer circumference side of the coil, a circuit board fixed on the base, and a sensing element fixed on the circuit board. The sensing element is located in a direction parallel with an optical axis of the lens. As the sensing element is positioned on the circuit board fixed on the base of the closed-loop lens driving device, a position of the lens can be considered/positioned accurately based on a current supplied to the coil and a magnetic field intensity in the lens driving device. A horizontal volume of a camera using the closed-loop lens driving device can by reduced when comparing with a traditional camera, and a wiring difficulty is reduced, too.

Description

Closed-loop lens drive

The present invention relates to the field of lens driving devices, and in particular, to a closed-loop lens driving device.

With the development of science and technology in recent years, various types of mobile devices such as laptops, tablets, mobile phones and even smart watches are equipped with small cameras. Today's cameras are basically equipped with autofocus. Focusing is generally achieved by a motor (lens driving device) driving the lens movement. In order to focus accurately and quickly, current closed-loop motors need to add a position detection device to detect the position of the lens, so that the movement of the lens can be controlled more accurately. In the existing technology, a position detection magnet is generally provided in a coil connected to the lens, and an inductor is provided at a position of the outer peripheral side of the coil opposite to the position detection magnet. The position of the position detection magnet is sensed by the sensor, so that The position of the lens in the direction of the optical axis can be known, for example, a lens driving device disclosed in US2014 / 0177056A1 with a publication date of June 26, 2014. However, the circuit board of the driving device is mostly located at the bottom, and the sensor generally needs to be fixed on the side of the casing of the driving device, which not only increases the lateral size of the camera, but also increases the difficulty of wiring. At present, all kinds of mobile devices are moving towards miniaturization and thinness, and higher requirements are also placed on cameras.

In view of this, our inventors are concentrating on further research and proceeding with research and development and improvement, with a better design to solve the above problems, and the invention came out after continuous testing and modification.

In view of this, it is necessary to provide a closed-loop lens driving device with a small size and a low wiring difficulty.

A closed-loop lens driving device for driving a lens includes a base, a lens holder for carrying the lens, a coil wound around the lens holder around an optical axis of the lens, and a coil provided on the outer peripheral side of the coil and the winding side of the coil A plurality of opposing magnets in a space; a frame connected to the base and used to fix the plurality of magnets; connected between the frame and the lens holder for supporting the lens holder suspension inside the frame and allowing the lens holder to move in the direction of the optical axis A plate spring; a circuit board fixed on the base; and a sensing element disposed on the circuit board and located in a direction parallel to the optical axis.

Further, viewed from the direction of the optical axis, the induction element is located on the inner peripheral side of the coil.

Further, the above-mentioned closed-loop lens driving device further includes a plurality of soft magnets arranged on the lens holder and located inside the coil.

As an implementation manner, the magnet is two pieces, which are respectively fixed at a set of opposite sides of the frame; the soft magnet is four pieces, which are symmetrically fixed on the inner peripheral side of the coil, and are opposite to the four corners of the frame.

As another implementation manner, the magnet is four pieces, which are respectively fixed at four sides of the frame; the soft magnet is four pieces, which are symmetrically fixed on the inner peripheral side of the coil, and are opposite to the four corners of the frame.

As another embodiment, the magnet is four pieces, which are respectively fixed at the four corners of the frame; the soft magnet is four pieces, which are symmetrically fixed on the inner peripheral side of the coil, and correspond to the middle positions of the four sides of the frame.

Preferably, the inductive element is disposed in one of the following manners: in the first manner, four inductive elements are disposed on the circuit board at positions corresponding to the four soft magnets one by one; in the second manner, the circuit board is provided Two induction elements are provided at positions corresponding to one of the four soft magnets in a one-to-one correspondence; in a third manner, an induction is disposed at a position corresponding to one of the four soft magnets on the circuit board element.

Further, the lens holder is provided with a plurality of slots for accommodating the plurality of soft magnets from the side close to the photographed object toward the base. The plurality of soft magnets are sheet-shaped and are opposite to the coil through the side wall forming the slot. A through hole for accommodating the lens is provided in the middle, and a plurality of slots for installing soft magnets are provided around the through hole.

Further, the base includes a square substrate and four column-shaped bearing portions extending vertically from four corners of the substrate, and a hole is formed on the substrate for light passing through the lens to pass through; the frame includes a square square The frame and the support feet extending from the four corners of the frame toward the load-bearing portion. The magnet is fixed between two adjacent load-bearing portions and is also located between the two support feet.

As an embodiment, the leaf spring is two pieces, including an upper leaf spring and a lower leaf spring; the upper leaf spring includes an inner connecting portion connected to an upper end of the lens base, an outer connecting portion connected to a frame, and an inner connecting portion. An elastic wrist portion connected to the outer connection portion; the lower plate spring includes an inner connection portion connected to the lower end of the lens base, an outer connection portion connected to the base, and an elastic wrist portion connected to the inner connection portion and the outer connection portion; The leaf spring is divided into two independent L-shaped reeds, which are electrically connected to the coil and the circuit board, and are used as a power supply path for the coil. A plurality of positioning holes are provided on the outer connection portion of the lower leaf spring. A positioning pin matching the positioning through hole is provided at the corresponding position of the hole.

A magnetic induction element is provided on the circuit board of the base of the closed-loop lens driving device. When the coil is energized (focusing by the lens driving device), the magnetic poles of the generated magnetic field are located at both ends in the direction of the optical axis, so that the induction element is on the circuit board of the base The magnetic field generated by the coil can be sensed, and the position of the coil can be determined based on the changed magnetic field and the current output to the coil, and the position of the mirror base can be adjusted accurately. Because the sensing element is located at the bottom of the lens holder, compared with the traditional method, the lateral volume of the camera is reduced, and the wiring difficulty is reduced.

Regarding the technical means of our inventors, several preferred embodiments are described in detail below in conjunction with the drawings, for the purpose of understanding and agreeing with the present invention.

The present invention will be described in further detail below with reference to specific embodiments and drawings.

The present invention provides a closed-loop lens driving device for driving a lens (not shown) to move in the direction of the optical axis of the lens. In the following, for convenience of description, the side closer to the subject is forward (upper, upper) in the direction of the optical axis, and the side farther from the subject is rearward (down, bottom) in the direction of the optical axis. As shown in FIGS. 1 to 6, the closed-loop lens driving device includes a base 1 and a housing 2 mounted on the base. An upper surface of the housing 2 is provided with an opening 21 as a light entrance, and a circular shape is also formed in the middle of the base 1. The through hole 14 is used as a light exit. When the casing is mounted on the base, a receiving space is formed between the casing 2 and the base 1 for receiving other components of the lens driving device. The closed-loop lens driving device further includes a lens holder 3 for fixing the lens, a driving coil 31, a magnet 5, a soft magnet 4, a circuit board 6, a plate spring 8, and a frame 9.

In this embodiment, the base 1 mainly includes a substantially square substrate 13 and four column-shaped bearing portions 12 extending vertically from four corners of the substrate 13 toward the front of the optical axis, and the through hole 14 is formed in the middle of the substrate 13 . An edge of the through hole 14 extends toward the front of the optical axis to form a ring-shaped retaining wall 15 for limiting the lens holder 3 and preventing dust.

The lens holder 3 is generally in a square column shape. The coil 31 is wound around the optical axis on the outer peripheral side of the lens holder 3. A through hole 32 for mounting a lens is provided in the middle of the lens holder. The diameter of the through hole 32 is larger than the outer diameter of the retaining wall 15. On the end surface of the lens holder 3 located in front of the optical axis direction, near the four corners are formed four slots 33 extending rearward (in the direction of the base) in the optical axis direction, and a soft magnet 4 is fixed in each slot 33. Each soft magnet 4 is in the shape of a square sheet, and is inserted into the slot 33 in parallel with the optical axis. Therefore, the soft magnet 4 and the coil 31 are disposed opposite to each other at a side wall forming the slot 33, and the slot 33 surrounds the through hole 32.

The frame 9 includes a substantially square frame 92 and support legs 91 extending from four corners of the frame 92 toward the load-bearing portion 12. The support leg 91 and the end of the load bearing portion 12 are formed with a structure capable of being engaged with each other or limiting the position, so as to prevent the support leg 91 and the load bearing portion 12 from being displaced when the closed-loop lens driving device is shaken. After the supporting leg 91 and the bearing portion 12 are connected, a magnet fixing frame for fixing the magnet 5 is enclosed with the edge portion of the frame 92 and the edge portion of the base plate 13 of the base 1. In this embodiment, two flat magnets are used, and are relatively fixed on the frame 9 and the base 1. The frame 9 is provided on the outer peripheral side of the lens holder 3, and the outer side of the coil 31 and the magnet 5 are opposed to each other with space. The casing 2 covers the outside of the frame 9.

The leaf spring 8 is used to support the suspension of the lens holder 3 in the upper part of the magnet fixing frame composed of the frame 9 and the base 1, and to make the lens holder 3 move along the optical axis direction. In this embodiment, the leaf spring 8 is two pieces and includes an upper leaf spring 81 and a lower leaf spring 82. The upper plate spring 81 includes an inner connecting portion 811 connected to the upper end of the mirror base 3, an outer connecting portion 812 connected to the frame, and an elastic wrist portion connecting the inner connecting portion 811 and the outer connecting portion 812. Specifically, the outer connecting portion 812 is connected to the rear end (the end surface located rearward of the optical axis direction) of the frame 92 of the frame 9. The lower plate spring 82 includes an inner connecting portion 821 connected to the lower end of the lens holder, an outer connecting portion 822 connected to the base 1, and an elastic wrist portion connecting the inner connecting portion 821 and the outer connecting portion 822. Specifically, the outer connecting portion 822 is connected to the front end (end surface located forward of the optical axis direction) of the substrate 13 of the base 1. The upper plate spring 81 has a single piece shape. The lower leaf spring 82 is divided into two independent L-shaped reeds, the two L-shaped reeds are not in contact with each other, and are separated into a reed having a shape of approximately a square on the outer circumference and a shape of a circular shape on the inner circumference, and two L The reed is electrically connected between the coil 31 and the circuit board 6 as a power supply path of the coil 31.

In addition, a plurality of positioning holes 823 are also provided on the outer connecting portion 822 of the lower plate spring 82, and a plurality of positioning pins 11 matching the positioning holes 823 are provided on the base 1 corresponding to the positioning holes 823.

The circuit board 6 is fixed on the base 1 and is located outside the retaining wall 15. An induction element 7 corresponding to the soft magnet 4 is provided on the circuit board 6. The sensing element 7 in this embodiment is a magnetoresistive (MR) element, and only one sensing element 7 is provided. Viewed from the direction of the coil winding axis (that is, the optical axis), the induction element is located on the inner peripheral side of the coil, and the induction element 7 and one of the four soft magnets 4 are spaced opposite each other. The intensity of the magnetic field generated in the rear. In specific implementation, the magnetoresistive (MR) element may be a Giant Magneto-Resistive (GMR) sensor or a Tunneling Magnetoresistance (TMR) sensor. When the circuit board 6 energizes the coil 31, the soft magnet 4 and the coil 31 form an electromagnet with magnetic poles located at both ends of the optical axis (front of the optical axis and rear of the optical axis), and the magnetic field generated by the magnetic field will be reluctance located behind the optical axis ( MR) element detected. When the amount of current applied to the coil 31 is different, the magnetic field intensity sensed by the magnetoresistive (MR) element is different. When the lens holder moves, the magnetic field intensity sensed by the magnetoresistive (MR) element will further change. The magnitude of the current and the magnetic field strength detected by the magnetoresistive (MR) element determine the specific position of the lens holder (lens) in the direction of the optical axis, and then determine whether the lens is accurately focused.

During specific work, the lens is installed at the through hole of the lens holder. When the coil around the lens holder is energized, a Lorentz force is generated under the action of the magnet, which pushes the lens holder to move. At the same time, the electromagnet composed of the coil and the soft magnets inside it also generates a magnetic field with magnetic poles located at both ends of the optical axis. , So that you can determine the current position of the coil, that is, the current position of the lens holder. The control system can accurately adjust the position of the lens holder by comparing the data with the current position of the lens holder.

In the present invention, a soft magnet is provided inside the coil of the closed-loop lens driving device, and an induction element is provided on the circuit board of the base. The induction element can determine the position of the coil by the strength of the magnetic field generated after the induction coil is energized, thereby accurately adjusting the position of the lens holder. Position to better achieve the camera's focus function. On the other hand, the sensing element is located at the bottom and the soft magnet is very thin. Compared with the traditional method, it reduces the lateral volume of the camera and reduces the difficulty of wiring.

In the above embodiment, the outer periphery of the frame and the lens holder is square, the magnets are two pieces, which are respectively fixed at a set of opposite sides of the frame, and the soft magnets are four, which are symmetrically fixed on the outer peripheral side of the lens holder, and are aligned with the four corners of the frame. relatively. In other embodiments, the outer periphery of the frame and the mirror base may be circular. Correspondingly, the magnet and the soft magnet are arc-shaped, and the magnets are fixed on the frame and are oppositely disposed (circularly symmetrical). The soft magnets are also circularly symmetrically fixed on the inner periphery of the coil. Side, as long as the soft magnet and the magnet are disposed staggered from each other in the lens radial direction. In other embodiments, in addition to the square and the circle, the frame may also be other polygons, such as a hexagon or an octagon.

In the above embodiment, a soft magnet is used to enhance the magnetic field when the coil is energized. In other embodiments, the soft magnet may be omitted, and the position of the lens may be determined by directly inducing the magnetic field when the coil is energized by the induction element.

In other embodiments, the outer periphery of the frame is square, the magnets are four pieces and can be fixed at the four corners of the frame, and the soft magnets can correspond to the middle positions of the four sides of the frame, so that the soft magnets and the magnets are staggered in the radial direction of the lens. Settings.

In other embodiments, four magnets may be provided, and the four sides of the frame may be provided respectively. When the frame is circular, the four magnets can be evenly and symmetrically distributed, and are staggered with the soft magnets in the radial direction of the lens.

In other embodiments, the number of the soft magnets may be two pieces, and the soft magnets are staggered with the magnets in the radial direction of the lens.

In the above embodiment, only one magnetic induction element is provided on the circuit board. In other embodiments, one induction element is provided at all positions on the circuit board corresponding to all the soft magnets, so as to achieve more accurate lens position positioning. Alternatively, two induction elements are disposed on the circuit board at positions corresponding to one of the four soft magnets in a one-to-one correspondence.

In the above embodiments, the sensing element is disposed inside the coil in the optical axis direction. In other embodiments, the sensing element may overlap the position of the coil in the optical axis direction.

In summary, the technical means disclosed in the present invention can effectively solve problems such as knowledge, and achieve the intended purpose and effect. It has not been published in publications before application, has not been publicly used, and has long-term progress. The invention referred to in the Patent Law is correct, and he filed an application in accordance with the law. He earnestly hopes that Jun will give him a detailed review and grant a patent for the invention.

However, the above are only a few preferred embodiments of the present invention. When the scope of implementation of the present invention cannot be limited in this way, that is, equivalent changes and modifications made according to the scope of the patent application and the content of the invention specification of the present invention are It should still fall within the scope of the invention patent.

〔this invention〕

1‧‧‧ base

11‧‧‧ positioning pin

12‧‧‧bearing department

13‧‧‧ substrate

14‧‧‧through hole

15‧‧‧ retaining wall

2‧‧‧ shell

21‧‧‧ opening

3‧‧‧ mirror mount

31‧‧‧Drive coil

32‧‧‧through hole

33‧‧‧slot

4‧‧‧ soft magnet

5‧‧‧magnet

6‧‧‧Circuit Board

7‧‧‧ sensor element

8‧‧‧ leaf spring

81‧‧‧ Upper leaf spring

811‧‧‧ inside connection

812‧‧‧outside connection

82‧‧‧ Lower leaf spring

821‧‧‧Inside connecting part

822‧‧‧outer connection

823‧‧‧ Positioning hole

9‧‧‧ frame

91‧‧‧ support feet

92‧‧‧box

FIG. 1 is a schematic structural diagram of an embodiment of a battery-attachment sensing structure of a closed-loop lens driving device provided by the present invention. FIG. 2 is a schematic structural diagram of a lens holder of this embodiment. FIG. 3 is a schematic structural diagram of a base and a circuit board portion of this embodiment. FIG. 4 is a schematic structural diagram of an upper plate spring in this embodiment. FIG. 5 is a schematic structural diagram of a lower leaf spring of this embodiment. FIG. 6 is a schematic structural diagram of a frame of this embodiment.

Claims (10)

A closed-loop lens driving device for driving a lens. The improvement includes: a base; a lens holder for carrying the lens; a coil wound around the periphery of the lens holder around an optical axis of the lens; A plurality of opposite magnets wound on the side space; a frame connected to the base and used to fix the plurality of magnets; connected between the frame and the lens holder for supporting the lens holder suspension inside the frame and allowing the lens holder to follow the light A plate spring moving in the axial direction; a circuit board fixed on the base; and a sensing element disposed on the circuit board and positioned in a direction parallel to the optical axis. The closed-loop lens driving device according to item 1 of the patent application scope, wherein the sensing element is located on the inner peripheral side of the coil as viewed from the direction of the optical axis. The closed-loop lens driving device according to item 1 of the scope of patent application, further comprising a plurality of soft magnets arranged on the lens holder and located inside the coil. The closed-loop lens driving device according to item 3 of the scope of patent application, wherein the magnet is two pieces, which are respectively fixed at a set of opposite sides of the frame; the soft magnet is four pieces, which are symmetrically fixed on the inner peripheral side of the coil, and The four corners of the frame are opposite. The closed-loop lens driving device according to item 3 of the scope of patent application, wherein the magnet is four pieces, which are respectively fixed at the four sides of the frame; the soft magnet is four pieces, which are symmetrically fixed at the inner peripheral side of the coil, and are connected to the four corners of the frame relatively. The closed-loop lens driving device according to item 3 of the scope of patent application, wherein the magnet is four pieces, which are respectively fixed at the four corners of the frame; the soft magnet is four pieces, which are symmetrically fixed on the inner peripheral side of the coil, and are connected to the four sides of the frame Corresponds to the middle position. The closed-loop lens driving device according to item 4 of the scope of patent application, wherein the way of setting the sensing element is one of the following ways: way one, the circuit board is provided with positions corresponding to the four soft magnets on a one-to-one basis. Four sensing elements; mode two, two sensing elements are provided on the circuit board at positions corresponding to one of the four pieces of the soft magnets opposite one another; mode three, the circuit board is connected to the four pieces An inductive element is provided at a corresponding position in the soft magnet. The closed-loop lens driving device according to item 7 of the scope of patent application, wherein the lens holder is provided with a plurality of slots for accommodating the plurality of soft magnets from the side close to the object to be photographed to the base, and the plurality of soft magnets are in pieces In the middle, a through hole for accommodating a lens is provided in the middle opposite to the coil through a side wall forming the slot, and a plurality of slots for installing soft magnets are provided around the through hole. The closed-loop lens driving device according to item 7 of the scope of patent application, wherein the base includes a square substrate and four column-shaped bearing portions extending vertically from four corners of the substrate, and the substrate is formed with a lens for passing through the lens. A hole through which light passes; the frame includes a square box and supporting feet extending from the four corners of the box toward the bearing section, and the magnet is fixed between two adjacent bearing sections and is also located on the two supporting feet between. The closed-loop lens driving device according to item 9 of the scope of patent application, wherein the leaf spring is two pieces, including an upper leaf spring and a lower leaf spring; the upper leaf spring includes an inner connecting portion connected to the upper end of the lens base, and is connected to An outer connecting portion of the frame and an elastic wrist connecting the inner connecting portion and the outer connecting portion; the lower plate spring includes an inner connecting portion connected to a lower end of the lens base, an outer connecting portion connected to the base, and the inner connecting portion An elastic wrist part connected to the outer side; the lower plate spring is divided into two independent L-shaped reeds, which are electrically connected to the coil and the circuit board, and are used as a power supply path for the coil; the outer connection part of the lower plate spring A plurality of positioning holes are provided on the base, and positioning pins matching the positioning through holes are provided at corresponding positions of the base and the positioning holes.