KR200370323Y1 - Actuator For Auto Focusing In Camera - Google Patents

Abstract

The present invention is compactly designed to be applied to a small camera mounted in a narrow space such as a mobile phone, and is used for auto focusing of a camera based on a voice coil actuator that can move a relatively short distance precisely without eccentricity. It relates to the actuator. The actuator 1 for auto focusing according to the present invention includes a lens barrel 10 equipped with a focusing lens matching the optical axis, a coil 21 wound in a direction perpendicular to the magnetic flux, and the lens barrel 10 mounted and transported. Carrier 20, which is mounted on both sides of the magnet 31 to face each other to form a magnetic flux of the magnetic flux and to support the yoke 30, the yoke 30 is inserted into the carrier 20 inside the image sensor ( Actuator for automatic camera focusing including a base (40) mounted on the CCD), and an elastic member 50 for restraining the linear movement of the carrier (20), the section formed of the yoke 30 as a closed The magnet 31 to be mounted is characterized in that it is formed in an arc shape.

Description

Actuator For Auto Focusing In Camera

(Technology)

The present invention relates to an actuator for automatic camera focusing. More specifically, the present invention is compactly designed to be applied to a small camera mounted in a narrow space such as a mobile phone, and moves a relatively short distance precisely without eccentricity. The present invention relates to an actuator for auto focusing of a camera based on a voice coil actuator.

(Background)

As an actuator for automatic camera focusing, a mechanical actuator for converting a rotational motion of a motor into a linear motion of a lens through a gear has been widely used.

However, these mechanical actuators were unable to avoid static-dynamic errors due to friction, mechanical deformation, and backlash associated with the operation of the motor and gears, making it impossible to precisely control the motor and gears. Due to its occupied space, it was not suitable for camera miniaturization.

Voice coil actuators have been developed as actuators capable of overcoming the limitations of such mechanical actuators. The voice coil actuator is an actuator that uses the Lorentz force generated by the induced magnetic force of the coil in a linear motion in a static magnetic field formed by a permanent magnet, and is suitable for constructing a system for precisely linearly moving a relatively short distance.

Voicecoil actuators have been used in ultra-precision linear movement systems such as moving pickup heads in hard or optical discs.

12 is a schematic diagram of a voice coil actuator applied to a pickup head of a hard disk. As shown in the drawing, the conventional voice coil actuator 100 includes a bobbin 110 equipped with a focusing lens 111 coinciding with an optical axis, a carrier 120 in which a coil 121 is wound in a direction perpendicular to a magnetic flux, A magnet 131 is mounted to face each other and includes a yoke 130 that forms a closed path of magnetic flux, and an elastic member 140 that restrains linear movement of the carrier 120. The voice coil actuator 100 of this configuration determines the linear motion of the carrier 120 according to the change of the equilibrium state of the Lorentz force by the coil 121 and the magnet 131 and the elastic force of the elastic member 140 to focus. Adjust

However, such a voice coil actuator 100 is mainly used to maintain a short focal displacement, but the size is large for use for a small camera, and the lens axis is distorted and moved during multifocal adjustment, which causes a problem of deterioration of the focusing accuracy. have.

An object of the present invention is to solve the problems in the conventional camera automatic focusing actuator as described above, the camera autofocus compact in size so as to be suitable for small cameras mounted in a narrow space such as a mobile phone It is to provide an actuator for adjustment.

The object of the present invention is to provide a compact size and precisely maintain the positioning of the carrier relative to the base when focusing, thereby preventing deterioration of the focusing accuracy due to the distortion of the lens axis and eccentricity. It is intended to provide an actuator for automatic camera focusing.

1 and 2 are exploded perspective and assembly cross-sectional view of an exemplary automatic focusing actuator of the present invention;

3 is an assembled perspective view of FIG. 1;

4 is a perspective view showing initial point settings of a lens barrel and a carrier;

5 and 6 are exploded perspective and assembly cross-sectional view of another actuator of the present invention,

Figure 7 and Figure 8 is an exploded perspective view and assembly cross-sectional view of another actuator of the present invention,

9 and 10 are exploded perspective view and assembly cross-sectional view of another actuator of the present invention;

11 is a perspective view illustrating a mounting position of an infrared cut filter;

12 is an exploded perspective view of a conventional voice coil actuator.

<Description of Symbols for Main Parts of Drawings>

1: actuator of the present invention 10: lens barrel

11, 23: screw 20: carrier

21: coil 22: guide pin

30: York 31: magnet

40: base 41: opening

42: hole 50: elastic member (plate spring)

51: space 60: board

70: cover 80: infrared cut filter

According to the present invention, a lens barrel equipped with a focusing lens coinciding with an optical axis, a carrier in which a coil is wound in a direction perpendicular to the magnetic flux, and the lens barrel is mounted and transported, and magnets are mounted on both sides so that the magnetic path is closed. And a yoke into which the carrier is inserted therein, a base supporting the yoke and mounted on the image sensor, and an elastic member for restraining linear movement of the carrier.

The actuator for auto focusing of the camera according to the present invention is characterized in that the closing section of the yoke and the magnet mounted thereon are formed in an arc shape.

Preferably, the lens barrel is screwed with the carrier to set an initial point of the lens barrel.

Preferably, the elastic member is composed of two leaf springs used in combination as a terminal required for the operation of the actuator.

Preferably, the open side of the yoke is mediated to block magnetic line leakage.

Hereinafter, with reference to the accompanying drawings will be described in detail the automatic focusing actuator for a camera according to the present invention. The following embodiments are merely illustrative of the auto focusing actuator for a camera according to the present invention, and are not intended to limit the scope of the present invention.

1 and 2 are an exploded perspective view and an assembly cross-sectional view of an exemplary automatic focusing actuator of the present invention, Figure 3 is an assembled perspective view of Figure 1, Figure 4 is a perspective view showing the initial setting of the lens barrel and the carrier, Figure 5 and Figure 6 is an exploded perspective view and an assembly cross-sectional view of another actuator of the present invention, Figures 7 and 8 are an exploded perspective view and an assembly cross-sectional view of another actuator of the present invention, Figure 9 and Figure 10 is an exploded perspective view of another actuator of the present invention 11 is a perspective view illustrating a mounting position of the infrared cut filter.

As shown in Figures 1 to 11, the camera autofocus adjustment actuator 1 according to the present invention, the lens barrel 10, the carrier 20, the yoke 30, the base, like the conventional voice coil actuator 40, and the elastic member 50 is basically included.

As is known, the lens barrel 10 is equipped with focusing lenses so as to coincide with the optical axis, and is inserted into the carrier 20 linearly moving to adjust the focus by linearly moving with the carrier 20.

In the periphery of the carrier 20, a coil 21 for generating a Lorentz force by interacting with the magnet 31 to form an induced electromotive force is wound in a direction perpendicular to the magnetic flux.

Since setting the initial point so that the distance between the subject and the image sensor is constant, moving the lens by the displacement of the distance is an operation of autofocusing, the tolerance of the BFL should be kept below 10 μm, for example. It is difficult to keep the distance constant due to tolerances and UV adhesive tolerances.

In order to overcome this problem, in the present invention, as shown in FIG. 4, the lens barrel 10 and the carrier 20 are always coupled by setting the initial point of the lens barrel 10 by combining the screws 11 and 23. It is possible to set the initial point to the same position, which enables more accurate autofocus.

The carrier 20 is inserted into the yoke 30 and the permanent magnets 31 are mounted on both sides of the yoke 30 so as to face each other. As a result, an induction magnetic force of the coil is generated in the magnetic field formed by the permanent magnet 31 to cause the linear motion of the carrier 20.

According to a feature of the present invention, the yoke 30 is formed as a closed portion of the side in which the magnet 31 is inserted, and the magnet 31 mounted thereto is formed in an arc shape. Of course, as the yoke 30 and the magnet 31 are arcuate, the carrier 20 and the plate 60 to be described later are also formed in a corresponding shape.

As the yoke 30 and the magnet 31 are formed in an arc shape as described above, an area of the lungs can be formed relatively larger than that of only the rectangular parallelepiped shape, thereby increasing the force of the actuator and the lens. As the yoke 30 and the magnet 31 are formed with the same curvature as the barrel 10, the relative occupied space is reduced, which is advantageous in miniaturization, and the uniformity to the waste is further improved.

The yoke 30 is supported by the base 40, and the base 40 is mounted on an image sensor (eg, CCD: not shown) which is an image memory device. In the illustrated embodiments, an approximately C-shaped base 40 having a central opening 41 in communication with the image sensor is illustrated, but is not limited thereto.

As shown, the open side of the yoke 30 may be mediated to the plate 60 to eliminate the loss to the waste formed in the yoke 30 and to uniform the magnetic flux density in the yoke 30.

Since the strength of the magnetic field is the number of lines of magnetic force per unit area, applying the plate 60 to block the lines of magnetic force out of the yoke improves the uniformity of the magnetic flux density, increases the force in the optical axis direction, and helps to block the eccentricity of the lens. .

The elastic member 50 restrains linear movement of the carrier 20 by pressing the carrier 20 against the base 40. That is, when a current is applied to the coil 21, Lorentz force is generated by interaction with the permanent magnet 31, and the carrier 120 moves linearly according to the Lorentz force and the magnitude of the elastic force of the elastic member 50. It is controlled.

The elastic member 50 is not particularly limited as long as it can pressurize the carrier 20 with an appropriate modulus of elasticity, and as shown, a leaf spring can be preferably used. The leaf spring 50 may be disposed with a space 51 interposed above the carrier 20 as shown in FIGS. 1 and 5, and the carrier 20 as shown in FIGS. 7 and 9. It can also be arranged up and down around.

In the case of applying two leaf springs as the elastic member 50, the related parts can be reduced by using these leaf springs as signal terminals and ground terminals necessary for the operation of the actuator 1 of the present invention.

In addition, when the general coil spring is used as the elastic member 50, the spring must be fixed to two points on the outer side of the carrier, and a guide must be installed to improve safety. It is useful for preventing eccentricity and miniaturization by uniform elasticity because it has a small footprint and is in surface contact.

Reference numeral 70 denotes the base 40 of the base 40 so that the elastic modulus of the elastic member 50 remains constant after the carrier 20, the lens barrel 10, the yoke 30, and the elastic member 50 are mounted as a cover. It is fixed at the specified height.

Preferably, the guide pin 22 and the hole 42 may be formed in the carrier 20 and the base 40, respectively, so that the guide pins 22 and the holes 42 may be pin-hole bonded to each other. The position of the carrier 20 relative to 40 is kept in place.

As described above, the conventional voice coil actuator is mainly used for a hard disk pickup head, and is mainly used for short focus, not multifocal, and is large in size for use in a small camera module, and the lens axis is twisted and moved during multifocal adjustment. Although there is a problem in that the precision of adjustment is lowered, the present invention prevents the shaft distortion or the unintentional movement of the lens because the carrier 20 is held in the pin-hole coupling to the base 40.

In the present invention, an infrared cut filter (IR CUT FILTER) widely applied to a camera is attached to the base 40 instead of the lens barrel 10. As shown in FIG. 11, when the infrared cut filter 80 is applied to the lens barrel 10, the filter wafer must be processed into a circular shape requiring round cutting, so that the defect rate of the particles is high and the lens is damaged during assembly. Particles may fall on the lens), but when applied to the base 40, since the rectangular processing is not circular, the processing defect rate is low and there is no fear of lens damage.

5 and 7 are embodiments in which the yoke 30 is inverted by 180 degrees in comparison with the embodiments of FIGS. 1 and 9, and the actuator 1 of the present invention is provided with a yoke (relative to the base 40). 30 shows that it can also be assembled upside down.

When the yoke 30 is inverted and assembled as shown in FIG. 5, the plate 60 is positioned on the opposite side of the yoke 30 with the carrier 20 interposed to block the open side of the yoke 30.

The actuator for auto focusing camera 1 according to the present invention described above has the following effects.

First, by forming the closing section of the yoke 30 and the magnet 31 in the shape of an arc, the relative occupied space is reduced to meet the miniaturization of the camera, the force increases in the optical axis direction, and the uniformity to the lung is improved.

Second, by screwing the lens barrel 10 and the carrier 20, the initial point of the lens barrel 10 can be precisely and easily set.

Third, by using the leaf spring as the elastic member 50, it is possible to maintain the uniformity of the elasticity with a small occupied area, which is useful for miniaturization of the camera and prevention of eccentricity, and also by using the leaf spring as a terminal to reduce related parts Can be.

Fourth, by mediating the plate 60 which blocks the leakage of magnetic force lines on the open side of the yoke 30, the uniformity of the magnetic flux density is improved and the eccentricity of the lens is effectively blocked.

Fifth, by realizing the positioning of the carrier 20 with respect to the base 40 by pin-hole coupling of the guide pin 22 and the hole 42, magnetic flux imbalance due to the movement of the carrier during shaft distortion or initial point adjustment occurs. The focusing of the camera can be precisely realized without eccentricity.

Sixth, the infrared cut filter is attached to the base 40 instead of the lens barrel 10, thereby reducing the possibility of lens damage by particles.

Seventh, there is a convenience that can be assembled upside down yoke 180 degrees.

Claims (4)

A lens barrel 10 equipped with a focusing lens coinciding with the optical axis, a coil 20 wound around the magnetic flux in a direction perpendicular to the magnetic flux, and a carrier 20 in which the lens barrel 10 is mounted and transported, and magnets 31 on both sides. It is mounted facing each other to form a waste path of the magnetic flux and the yoke 30 is inserted into the carrier 20 therein, the base 40 supporting the yoke 30 and mounted on the image sensor (CCD), and the In the actuator for the automatic focus control of the camera comprising an elastic member 50 for restraining the linear movement of the carrier 20, Actuator for the automatic focus control of the camera, characterized in that the section formed by the closing of the yoke (30) and the magnet (31) attached thereto is formed in an arc shape. The actuator of claim 1, wherein the lens barrel (10) is coupled to the carrier (20) with screws (11, 23) to set an initial point of the lens barrel (10). The actuator of claim 1, wherein the elastic member is composed of two leaf springs which are used as a terminal required for the operation of the actuator. The actuator for camera autofocus control according to claim 1, characterized in that the open side of the yoke (30) is interposed with a plate (60) for blocking magnetic lines leakage.