KR102424581B1 - Actuator device for camera lens autofocusing - Google Patents

Abstract

The present invention relates to an actuator device for camera lens autofocusing. That is, the present invention comprises: a housing which includes a base and a cover having a plurality of bent extension parts extending toward the base, and which is provided with open top and bottom; a carrier having a through-hole installed to be able to move up and down inside the housing and a holding groove accommodating the bent extension parts; an upper spring located between the cover and the carrier and a lower spring interposed between the carrier and the base; a coil wound on an outer circumferential surface of the carrier; a plurality of magnets disposed opposite to each other with the carrier interposed therebetween; and a plurality of magnetic force reaction members which are covered by the coil while being fixed to the outer circumferential surface of the carrier, and which correspond to the magnets on a one-on-one basis with the coil interposed therebetween, wherein the holding groove is filled with a damper that maintains a coupling state of the bending extension parts to the holding groove. Accordingly, the actuator device for camera lens autofocusing of the present invention is capable of quickly and stably implementing an autofocusing function since the time required for the carrier to stop and stabilize at the focused position is short. In addition, since the upper and lower springs supporting the carrier are supported by the damper, there is no damage to or movement of the carrier by external shock. As such, there is no unintentional change in the focal distance.

Description

Actuator device for camera lens autofocusing

The present invention relates to an actuator device for auto focusing of a camera lens, which is applied to the field of auto focusing of a camera lens.

In recent years, not only portable cameras but also mobile communication terminals such as smartphones and tablet PCs are equipped with auto-focusing, that is, auto-focusing cameras. The auto focus adjustment function is a function of moving the lens forward or backward along the optical axis direction so that the image of the subject is clearly formed on the image sensor. do.

Korean Patent Laid-Open Publication No. 10-2011-0055932 discloses an actuator for auto-focusing according to an example of the related art. The actuator advances and retreats the lens barrel by electromagnetic force generated between a coil and a magnet. It has four magnets to increase the forward and backward speed to realize fast autofocusing.

Republic of Korea Patent Publication No. 10-2011-0055932

The present invention was created to solve the above problems, and an object of the present invention is to provide an actuator device for auto-focusing a camera lens that is improved so as to realize a fast and accurate auto-focusing function.

Another object of the present invention is to provide an actuator device for auto-focusing a camera lens that is advantageous in reducing cost and being lightweight and compact.

The actuator device for auto-focusing a camera lens of the present invention as a means of solving the problems for achieving the above object is composed of a base for providing support and a cover coupled to the base, the housing being opened up and down through an opening; a carrier installed in the housing so as to be able to move up and down and having a through hole for accommodating the lens; a coil wound on the outer circumferential surface of the carrier; a plurality of magnets disposed on opposite sides with the carrier interposed therebetween; A plurality of magnetic force reaction members are provided that are fixed to the outer circumferential surface of the carrier and are covered by the coil and correspond to the magnet one-to-one with the coil interposed therebetween.

In addition, the actuator device for camera lens auto-focusing of the present invention as a means of solving the problem for achieving the above object includes a base that provides support and a cover having a plurality of bending extensions coupled to the upper portion of the base but extending toward the base Consisting of, and the housing opened up and down through the opening; a carrier installed in the housing so as to be able to move up and down, a through hole for accommodating the lens, and a holding groove for accommodating the bent extension; Installed inside the housing, elastically supporting the carrier to converge to a reference height, the upper spring positioned between the cover and the carrier and the lower spring interposed between the carrier and the base; a coil wound on the outer circumferential surface of the carrier; a plurality of magnets disposed on opposite sides with the carrier interposed therebetween; It is covered by the coil in a state fixed to the outer circumferential surface of the carrier, and includes a plurality of magnetic force reaction members corresponding to the magnet one-to-one with the coil interposed therebetween. The damper that holds it is filled.

A plurality of lower protrusions are formed on the lower spring, and a lower holding groove for accommodating the lower protrusion is formed in the carrier, and the lower holding groove is filled with a lower damper that maintains the coupling state of the lower protrusion to the lower holding groove. have.

In addition, despite the change in position due to the lifting of the carrier, the geometric center of each of the pair of magnetic force responding members is located above the geometric center of the magnet corresponding to itself, and even when the carrier is maximally raised in the housing, The lower edge of the magnetic force reaction member is configured to be positioned lower than the upper edge of the magnet corresponding to itself.

In addition, the width of the magnetic force reaction member is 1/25 to 1/4 of the width of the magnet, the magnet and the magnetic force reaction member take the shape of a rectangular plate, and the horizontal length of the magnetic force reaction member is the horizontal length of the magnet 1/5 to 1/2, and the longitudinal length of the magnetic force reaction member is 1/10 to 1/2 of the longitudinal length of the magnet.

In addition, the magnetic force reaction member is made of stainless steel (stainless steel).

In addition, a seating groove is formed on the outer circumferential surface of the carrier, and the magnetic force reaction member is configured to be seated in the seating groove.

In addition, it elastically pressurizes the carrier to converge to a reference height within the housing, and further includes an upper spring interposed between the cover and the carrier, and a lower spring interposed between the base and the carrier.

The actuator device for auto-focusing a camera lens of the present invention made as described above has a short period of time until the carrier stops at a focused position and stabilizes, so that a fast and stable auto-focusing function can be implemented.

In addition, since the upper and lower springs supporting the carrier are supported by the damper, there is no damage or movement of the carrier due to an external impact, so that an unintentional change in focal length does not occur.

1 and 2 are a perspective view and an exploded perspective view of an actuator device for auto-focusing a camera lens according to an embodiment of the present invention.
3 is a longitudinal cross-sectional view of FIG. 1 taken along line III-III.
4 is an exploded perspective view illustrating the carrier, the magnet, the winding coil, and the magnetic force reaction member of FIG. 1 .
FIG. 5 is a front view showing only the magnet and the magnetic force reaction member in the actuator device for auto-focusing the camera lens of FIG. 2 to be overlapped.
Figure 6a is a graph showing the test results regarding the stabilization time (settling time) of the conventional actuator device for auto-focusing a camera lens, Figure 6b is a stabilization time of the actuator device for auto-focusing a camera lens according to an embodiment of the present invention This is a graph showing the test results.
7 is an exploded perspective view illustrating a modified example of an actuator device for auto-focusing according to an embodiment of the present invention.
FIG. 8 is a view for explaining a connection method of the bent extension part to the holding groove shown in FIG. 7 .

Hereinafter, one embodiment according to the present invention will be described in more detail with reference to the accompanying drawings.

Hereinafter, an actuator device for auto-focusing a camera lens according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Terms used in this specification are terms used to properly express preferred embodiments of the present invention, which may vary depending on the intention of a user or operator or customs in the field to which the present invention belongs. Accordingly, definitions of these terms should be made based on the content throughout this specification.

1 and 2 are perspective and exploded perspective views of an actuator device for auto-focusing a camera lens according to an embodiment of the present invention, FIG. 3 is a longitudinal cross-sectional view of FIG. 1 taken along line III-III, and FIG. It is an exploded perspective view showing the carrier, the magnet, the winding coil, and the magnetic force reaction member. 1 to 4 together, the actuator device 10 for auto-focusing a camera lens according to an embodiment of the present invention includes a housing 11 including a base 12 and a cover 16, a frame (frame) 20, carrier (carrier) 30, coil (coil) 41, a pair of magnets 45, a pair of magnetic force reaction member 50, upper spring 25, and lower spring (27) is provided.

The base 12 is a member having a substantially rectangular shape in plan view, and includes a substantially rectangular plate having an opening 13 formed in the center thereof, and four pillars protruding upward from the four corners of the rectangular plate. (15) is provided. A plurality of step surfaces are formed on the inner circumferential surface defining the opening 13 , and an image sensor (not shown) and at least one type of optical filter (not shown) are fitted to the inner circumferential surface and mounted on the base 12 . The image sensor and the optical filter are arranged in an optical axis alignment with a lens (not shown) mounted on the carrier 30 .

The cover 16 has an upper side of the rectangle and four sidewalls 18 that are bent downwardly and extend from the four corners of the upper side of the rectangle. An opening 17 is formed in the upper surface of the cover 16 so that light is received from the upper side of the cover 16 to the inside of the housing 11 . The cover 16 is made of a metal material, and the sidewall 18 of the cover 16 functions as a yoke to limit the magnetic field of the pair of magnets 45 from being dispersed out of the housing 11 . .

The frame 20 includes a rectangular plate in which an opening 21 corresponding to the opening 17 of the cover 16 is formed in the center, and four plates protruding downward from the four corners of the plate. It has legs 22 and is fixedly disposed in the inner space of the housing 11 . Specifically, the four legs 22 of the frame 20 overlap the four posts 15 of the base 12 , and the lower end of each leg 22 is the four corners of the square plate of the base 12 . is supported on

The carrier 30 is a ring-shaped member in which the through hole 31 opened in the vertical direction is formed in the center, and is disposed so as to be able to move up and down inside the housing 11 . A lens barrel (not shown) for fixing and supporting a lens (not shown) is inserted and fixedly mounted on the inner circumferential surface 32 of the carrier 30 serving as the boundary of the through hole 31 . A coil 41 is wound on the outer circumferential surface 33 of the carrier 30 . At the upper end and lower end of the carrier 30, an upper flange 35 and a lower flange 36 that prevent the wound coil 41 from falling off from the outer circumferential surface 33 of the carrier 30 are radially formed.

A pair of magnets 45 are disposed in opposite directions with the carrier 30 interposed therebetween in the housing 11 , and are disposed inside the housing 11 so as to face the inner surface of the cover side wall 18 and face each other. is fixed Specifically, each magnet 45 has a rectangular plate shape, and when the base 12 and the frame 20 are combined, a pair of adjacent legs 22 of the frame 20 and the frame 20 One corner of the square plate and one edge of the square plate of the base 12 are fitted and fixed in a rectangular window defined by the (window). However, the shape of each magnet 45 is not necessarily limited to a rectangular plate shape.

In this case, when the inner surface of the housing 11 has a rectangular shape in which the first, second, third, and fourth surfaces are continuously connected, the magnet 45 is disposed on the first and third surfaces of the housing 11 and , the magnet 45 is not disposed on the second and fourth surfaces.

That is, in the present invention, the number of magnets 45 is reduced compared to the prior art. Through this, there is an advantage in that the manufacturing cost is reduced. The weakening of electromagnetic force that may occur due to the decrease in the number of the magnets 45 can be supplemented by a pair of magnetic force response members 50 to be described later.

In the housing 11, the upper spring 25 is interposed between the cover 16 and the carrier 30, specifically, between the rectangular plate of the frame 20 and the upper flange 35 of the carrier 30, and the lower The spring 27 is interposed between the base 12 and the carrier 30 , specifically, between the rectangular plate of the base 12 and the lower flange 36 of the carrier 30 . The upper spring 25 and the lower spring 27 restrict the carrier 30 from flowing inside the housing 11 due to unintentional impact or vibration, and the carrier 30 within the housing 11 It is elastically pressed to converge to the reference height. The reference height of the carrier 30 may be, for example, the height of the carrier 30 when the lower end of the carrier 30 is supported in contact with at least a portion of the base 12 .

That is, when a current flows in the coil 41 , the carrier 30 is moved within the housing 11 by the electromagnetic force between the magnet 45 and the coil 41 despite the elastic force of the upper and lower springs 25 and 27 . It rises and moves to the height where the lens is in focus. The height of the carrier 30 at which the lens is focused is a position where the electromagnetic force applied to the coil 41 and the elastic force of the upper and lower springs 25 and 27 are balanced. On the other hand, when the current flowing in the coil 41 is cut off, the carrier 30 is lowered to the reference height by the elastic force of the upper and lower springs 25 and 27 to maintain a stopped state.

The lower spring 27 is formed with a terminal 29 bent downward and exposed to the outside of the base 12 . In addition, although not clearly shown in the drawings, the lower spring 27 maintains energizable contact with the coil 41 . Accordingly, power may be supplied from the outside of the housing 11 to the coil 41 through the lower spring 27 .

The pair of magnetic force reaction members 50 are fixedly coupled to the outer circumferential surface 33 of the carrier 30 so as not to be exposed and covered by the coil 41 wound around the carrier 30 . The pair of magnetic force response members 50 correspond one-to-one with the pair of magnets 45 and are disposed to face the magnets 45 corresponding to themselves with the coil 41 interposed therebetween. Specifically, a seating groove 37 is formed on the outer circumferential surface 33 of the carrier 30 , and the magnetic force reaction members 50 are mounted one by one in the seating groove 37 . In the illustrated embodiment, each magnetic force reaction member 50 has a smaller square plate shape than the magnet 45 , but the shape of the magnetic force reaction member 50 is not necessarily limited to a square plate shape. The magnetic force reaction member 50 may be made of stainless steel, which is a metal strong against oxidation, but is not necessarily limited thereto.

That is, as described above, if the magnet 45 is disposed on the first and third surfaces of the housing 11 , the magnetic force reaction member 50 is also disposed to face the first and third surfaces of the housing 11 . . In this case, it is preferable that the magnet 45 is not disposed to face the second and fourth surfaces of the housing 11 .

FIG. 5 is a front view showing only the magnet and the magnetic force reaction member in the actuator device for auto-focusing of the camera lens of FIG. 2 to be overlapped. 3 to 5 , the size and shape of the pair of magnetic force responding members 50 are the same, and the horizontal length SW of the magnetic force responding member 50 is the horizontal length of the corresponding magnet 45 . It is 1/5 to 1/2 of (MW), and the longitudinal length SH of the magnetic force reaction member 50 is 1/10 to 1/2 of the longitudinal length MH of the corresponding magnet 45 . Alternatively, the width of the magnetic force reaction member 50 is 1/25 to 1/4 of the width of the corresponding magnet 45 . When the size of the magnetic force reaction member 50 is smaller than the above-mentioned range, the magnetic attraction enhancement effect between the pair of magnets 45 and the pair of magnetic force reaction members 50 is insufficient, making it difficult to quickly adjust the focus of the lens. On the other hand, if the size of the magnetic force reaction member 50 is larger than the above-mentioned range, the magnetic attraction between the pair of magnets 45 and the pair of magnetic force reaction members 50 is excessive, so that precise lens focus adjustment is difficult. lose

On the other hand, inside the housing 11, the carrier 30 is spaced apart from the base 12 from the reference height in contact with the base 12, as shown in FIG. The geometrical centers SC_D and SC_U of each magnetic force reaction member 50 are located above the geometrical centers MC of the magnets 45 corresponding thereto. In FIG. 5, SC_D indicates the position of the geometrical center of the magnetic force responding member 50 when the carrier 30 is at the reference height, and SC_U is the magnetic force responding member when the carrier 30 is maximally raised in the housing 11 ( 50) represents the location of the geometric center. In addition, a rectangle shown by a two-dot chain line in FIG. 5 indicates the magnetic force reaction member 50 when the carrier 30 is maximally raised in the housing 11 .

When the carrier 30 is at the reference height in the housing 11, the upper edge 51 of the magnetic force reaction member 50 is positioned lower than the upper edge 46 of the magnet 45 corresponding to itself, and the magnetic force reaction The lower edge 52 of the member 50 is positioned higher than the lower edge 47 of the magnet 45 corresponding thereto. On the other hand, even when the carrier 30 is raised to the maximum in the housing 11, the lower edge 52 of the magnetic force reaction member 50 is located lower than the upper edge 46 of the magnet 45 corresponding to itself. At this time, the upper edge 51 of the magnetic force reaction member 50 may be positioned higher or lower than the upper edge 46 of the magnet 45 corresponding thereto.

If the above-described limit for the height of the magnetic force reaction member 50 is exceeded, the magnetic force reaction member 50 is positioned too low with respect to the magnet 45 corresponding thereto, so that the carrier 30 is moved to the housing 11 . It is strongly pulled downward by a strong attractive force with the magnet 45 when rising from the inside, which makes precise control of lens focus adjustment difficult.

Figure 6a is a graph showing the test results regarding the stabilization time (settling time) of the conventional actuator device for auto-focusing a camera lens, Figure 6b is a stabilization time of the actuator device for auto-focusing a camera lens according to an embodiment of the present invention This is a graph showing the test results.

Referring to FIG. 6A , in the conventional actuator device for camera lens auto-focusing having two pairs of magnets and not having a magnetic force reaction member, when the current input to the coil rises to 56 mA, the stroke of the carrier is 101.7 The settling time is 247.5 ms until it is stabilized at μm, and the overshoot is 10.28%.

However, referring to Figure 6b, the actuator device for camera lens auto-focusing according to an embodiment of the present invention having a pair of magnets and a pair of magnetic force reaction members, when the current input to the coil rises to 56mA of the carrier The settling time is 151.5 ms until the stroke is stabilized at 102.3 μm, and the overshoot is 0.27%.

Comparing FIGS. 6A and 6B, it can be seen that the actuator device for autofocusing a camera lens according to an embodiment of the present invention has a shorter stabilization time than that of the conventional one, and similar results can be obtained through several repeated tests.

According to the present invention, the stabilization time can be shortened when the magnet 45 and the magnetic force reaction member 50 are pulled to each other and stopped at the focus position. Accordingly, there is an effect that the focusing speed can be shortened.

In addition, when the horizontal and vertical sizes of the magnetic force response member 50 are adjusted, the preload and the slope, which are the driving performance of the actuator, can be adjusted by the attractive force of the magnet and the yoke. Accordingly, power consumption can be reduced.

7 is an exploded perspective view showing a modified example of the actuator device 10 for auto-focusing according to an embodiment of the present invention, and FIG. 8 is an excerpt showing a state in which the bending extension shown in FIG. It is a drawing.

Hereinafter, the same reference numerals as the above reference numerals refer to the same members having the same functions.

Referring to the drawings, it can be seen that the cover 16 is provided with four bent extension portions 16a , and holding grooves 34 are provided at four corners of the upper surface of the carrier 30 .

The bent extension portion 16a is a portion extending downwardly toward the base 12 and has four equal intervals. That is, when the bent extension portions 16a positioned opposite to each other in the radial direction are connected with a virtual straight line, the virtual straight line intersects at a right angle. The width and length of the bent extension portion 16a may vary as needed.

Further, the holding groove 34 is a groove corresponding to the bent extension portion 16a one-to-one, and a damper 38 is filled therein. The damper 38 serves to further shorten the stabilization time of the carrier 30 . That is, the stabilization time when the carrier 30 stops at the focusing position is further shortened. In other words, the focusing speed can be reduced by applying the damper 38 . As long as the stabilization time can be shortened, the type of material applied to the holding groove 34 may vary, and a liquid damper may be applied.

Although the present invention has been described with reference to the embodiments shown in the drawings, which are merely exemplary, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the true scope of protection of the present invention should be defined only by the appended claims.

10: actuator device 11: housing 12: base
13: Opening 15: Pillar 16: Cover
16a: bending extension 17: opening 18: side wall
20: Frame 21: Opening 22: Leg
25: upper spring 26: upper protrusion 27: lower spring
28: lower protrusion 29: terminal 30: carrier
31: through hole 32: inner circumference 33: outer circumference
34: holding groove 35: upper flange 36: lower flange
37: seating groove 38: damper 41: coil
45: magnet 50: magnetic force reaction member 51: upper edge
52: lower edge

Claims (8)

delete A housing comprising: a base providing support; a cover coupled to the upper portion of the base but having a plurality of bent extensions extending toward the base, the housing being opened up and down through an opening;
a carrier installed in the housing to be elevated and provided with a through hole for accommodating the lens and a holding groove for accommodating the bent extension;
Installed inside the housing, elastically supporting the carrier to converge to a reference height, the upper spring positioned between the cover and the carrier and the lower spring interposed between the carrier and the base;
a coil wound on the outer circumferential surface of the carrier;
a plurality of magnets disposed on opposite sides with the carrier interposed therebetween;
It is covered by the coil in a state fixed to the outer circumferential surface of the carrier, and includes a plurality of magnetic force reaction members corresponding to the magnet one-to-one with the coil interposed therebetween,
The cover does not move up and down, the carrier is elevating and lowering,
The holding groove is filled with a damper for maintaining the coupling state of the bent extension part of the cover with respect to the holding groove,
wherein the damper reduces the focusing speed so as to quickly stabilize when the carrier stops in the focusing position.
Actuator device for camera lens autofocusing. 3. The method of claim 2,
Despite the change in position due to the lifting of the carrier, the geometric center of each of the plurality of magnetic force responding members is located above the geometric center of the magnet corresponding to itself,
Even when the carrier is maximally raised in the housing, the lower edge of the magnetic force reaction member is configured to be positioned lower than the upper edge of the magnet corresponding to itself,
Actuator device for camera lens autofocusing. 3. The method of claim 2,
The width of the magnetic force reaction member is 1/25 to 1/4 of the width of the magnet,
Actuator device for camera lens autofocusing. 3. The method of claim 2,
The magnet and the magnetic force reaction member take the shape of a rectangular plate,
The horizontal length of the magnetic force responding member is 1/5 to 1/2 of the horizontal length of the magnet, and the vertical length of the magnetic force responding member is 1/10 to 1/2 of the vertical length of the magnet,
Actuator device for camera lens autofocusing. 3. The method of claim 2,
The magnetic force reaction member is made of stainless steel (stainless steel),
Actuator device for camera lens autofocusing. 3. The method of claim 2,
A seating groove is formed on the outer circumferential surface of the carrier,
The magnetic force reaction member is configured to be seated in the seating groove,
Actuator device for camera lens autofocusing. delete

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