KR100771205B1 - Device to focus automatically in optical lens - Google Patents

Abstract

An automatic focus control device for a camera is provided to increase a rotation force of a rotation object by a magnetic force by generating the magnetic field using a couple of coils to face each other, thereby increasing a straight line reciprocation driving force of a tube. An automatic focus control device for a camera comprises the followings: a base(10) with a cylinder type projection formed in upper surface; a bobbin(20) having multiple electromagnets wound by coils in a separated position by the same angle along an outer circumference; a rotation body(30) having a ring type permanent magnet; a housing(50) with a penetration hole to project light and image; a separation protecting unit(60) for elastically supporting an upper side of a tube in order to prevent the tube from being separated from the housing; and a cap(70) for fixing the separation protecting unit to the upper part of the housing.

Description

Camera focusing device {Device to focus automatically in optical lens}

1 is an exploded cross-sectional view showing an automatic focus control apparatus for a camera according to a first embodiment of the present invention;

2 is a cross-sectional view showing an automatic focusing apparatus for a camera according to the first embodiment of the present invention;

3 is a plan view showing the bobbin shown in FIG.

4 is a bottom view showing the housing shown in FIG. 1, FIG.

FIG. 5 is a plan view illustrating the separation prevention tool shown in FIG. 1;

Figure 6a is a plan view showing another embodiment of the departure prevention tool shown in Figure 5,

FIG. 6B is a schematic side view showing the relationship between the release preventing tool and the barrel shown in FIG. 6A; FIG.

7A to 7B are schematic plan views sequentially showing the operating relationship of the camera auto focusing apparatus according to the first embodiment of the present invention;

8 is a schematic plan view showing an automatic focus control apparatus for a camera according to a second embodiment of the present invention.

* Description of Signs for Main Parts in Drawings *

10: base 20: bobbin

30: rotating body 40: barrel

50: housing 60: release prevention

70: cap

The present invention relates to an automatic focusing apparatus for a camera, and more particularly, to an automatic focusing apparatus for a camera capable of precisely driving a barrel based on a magnetic driving method.

In general, 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 as an actuator for automatic camera focusing. 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 precisely linearly moving a relatively short distance. Such voicecoil actuators have been used in ultra-precision linear movement systems such as moving pickup heads in hard or optical discs. This conventional voice coil actuator automatically adjusts the focus of the lens by moving the barrel installed in the housing forward or backward.

By the way, the barrel is provided so as to maintain the elastic support in the housing by a leaf spring disposed at the top or the top / bottom. However, since the barrel is elastically supported only by the leaf spring without a separate support member, when the autofocus is adjusted, the lens axis is distorted during the forward or backward movement, and the tilting phenomenon occurs in the horizontal state due to the movement. There was a problem that the precision of the focus adjustment is lowered.

In order to solve the above problems, the present invention provides a rigid support for the barrel in the housing, to drive a straight reciprocating in a horizontally balanced state, the automatic focusing device for a camera capable of precise driving of the barrel during automatic focusing The purpose is to provide.

In addition, another object of the present invention to provide an automatic focusing apparatus for a camera that can increase the barrel straight reciprocating driving force.

In order to achieve the above object, the present invention provides an automatic focusing apparatus for linearly reciprocating a barrel installed in a camera, comprising: a base having a cylindrical protrusion fixed in the camera and having a lower portion of the barrel recessed on an upper surface thereof; A bobbin coupled to the cylindrical protrusion of the base and having a plurality of electromagnets each of which coils are wound at positions spaced at the same angle along an outer circumference; A rotating body having a support screw screwed to the outer circumference of the barrel, and a ring-shaped permanent magnet fixedly coupled to an outer side of the support, in which N poles and S poles are alternately magnetized by the same section; A housing detachably coupled to the base and having a space portion including the bobbin, a rotating body, and a barrel in an inner side thereof, and a through hole formed to project light and an image into the barrel on an upper side thereof; A release preventing device disposed above the housing and configured to elastically support an upper side of the barrel to limit a maximum forward driving distance of the barrel and prevent the barrel from being separated from the housing; And a cap detachably coupled to the upper side of the housing and configured to secure the release preventing tool to the upper side of the housing, wherein the rotating body is continuously driven by a pair of electromagnets facing each other among the plurality of electromagnets. It provides an automatic focus control device for a camera, characterized in that for reciprocating driving the barrel in a straight line in the axial direction as it rotates in place by a magnetic field generated in a plurality of electromagnets.

The permanent magnets of the rotating body have 8 poles magnetized by alternating N and S poles, and six electromagnets of the bobbin are formed, and the initial positions of the rotating bodies face each other around the bobbin among the six electromagnets. The centers of the pair of electromagnets are set at positions pivoted to one side with an angle of 15 ° with respect to the centers of the same magnetic poles facing each other.

In addition, the permanent magnet of the rotor is the N pole and the S pole alternately six magnetized, the bobbin electromagnet consists of four, the initial position of the rotor is centered on the bobbin of all four magnets It is of course also possible that the centers of the pair of electromagnets facing each other are set at a position pivoted to one side by 30 ° with respect to the center of the same magnetic poles facing each other.

The release prevention unit is a leaf spring portion is fixed to the upper end of the barrel; And a ring-shaped body extending downward in the periphery of the leaf spring part and fixed to the upper end of the fixing part.

In addition, the separation prevention portion is a disk portion formed with a through hole in the center; And at least two guide holes spaced apart from the disc portion, the plurality of guide holes being respectively inserted into the guide holes on the upper surface of the barrel so as to prevent rotation of the barrel during linear reciprocation of the barrel. It is also possible to provide a guide protrusion of.

The housing may have a plurality of coil indentation grooves formed at intervals such that the coils of the plurality of electromagnets are partially recessed to prevent rotation of the bobbin on an inner circumferential surface thereof.

The rotor is rotatably disposed between the upper end of the cylindrical protrusion of the base and the upper bottom of the housing, and the lubricant is provided on the upper end of the cylindrical protrusion of the base that contacts the bottom of the permanent magnet of the rotor. A first lube for receiving oil is formed, and a second lube oil receiving groove into which lubricant is charged may be formed on an upper surface of the support of the rotating body contacting the upper bottom surface of the housing.

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration of the automatic focus control apparatus for a camera according to a first embodiment of the present invention.

1 and 2 are an exploded cross-sectional view and a combined cross-sectional view showing an automatic focusing apparatus for a camera according to a first embodiment of the present invention, Figure 3 is a plan view showing a bobbin, Figure 4 is a bottom view showing a housing, Figure 5 6A is a plan view showing a release prevention tool, FIG. 6A is a plan view showing another embodiment of the release prevention tool, and FIG. 6B is a schematic side view showing a relationship between the release prevention tool and the barrel shown in FIG. 6A.

The automatic focusing device according to the first embodiment of the present invention for linearly driving the barrel 40 installed in the camera (not shown), the base 10, the bobbin 20, The rotor 30, the housing 50, the separation prevention 60 and the cap 70 is included.

The base 10 is fixed to a predetermined position in a camera (not shown), for example, a CCD (not shown) installed in the camera through a plurality of fixing parts 13 protruding from the bottom. The base 10 forms a see-through window 12 in the center so that light and an image projected through the barrel 40 are transferred to a CCD (not shown), and a cylindrical portion having a lower portion of the barrel 40 recessed on the upper surface thereof. The protrusion 11 is formed. In this case, the upper end of the cylindrical protrusion 11 is a region which is slid with the bottom of the permanent magnet 37 to be described later to minimize the frictional force with the permanent magnet 37 to smooth the rotation of the rotating body 30 to be described later Along the upper end of the cylindrical protrusion 11, the first lubricant receiving groove 15 is filled with the lubricant.

The bobbin 20 is detachably coupled to the cylindrical protrusion 11 of the base 10 through the through hole 21 formed in the middle term. In addition, as shown in FIG. 3, the six windings 24 are vertically formed at positions spaced at the same angle along the outer circumference, as shown in FIG. 3, and each of the plurality of windings 24 has a coil 23. The windings are formed, and the restricting protrusions 24 protrude to both sides of the upper end of the winding part 24 to prevent the coil 23 from being separated from the winding part 24 at the upper ends of the plurality of winding parts 24. The coil 23 and the winding 24 form one electromagnet 22 that forms a magnetic field when a current is applied. In the present embodiment, when a current is applied to the electromagnet, as the magnetic field is formed simultaneously in a pair of electromagnets facing each other, the driving force for rotating the rotating body 30, which will be described later, may be doubled as compared to the conventional art. In order to prevent tilting during rotation of the rotating body 30, the barrel 40 may be linearly reciprocated in a horizontally balanced state, thereby allowing the barrel 40 to be precisely moved.

The rotating body 30 includes a support 31 and a permanent magnet 37. The support 31 is formed with a screw portion 33 along the inner circumferential surface so as to be rotatably screwed to the screw portion 43 formed on the outer circumference of the barrel 40, the flange portion 32 is formed along the upper outer circumference. In this case, the upper surface of the flange portion 32 is an area that slides with the bottom surface of the protruding jaw 59 of the housing 50, which will be described later, to minimize the frictional force with this area plan to smoothly rotate the rotating body 30 Along the upper surface of the branch portion 32, a second lubricating oil receiving groove 35 having a predetermined width into which lubricating oil is charged is formed. The permanent magnet 37 formed in a ring shape is fixedly coupled to the inner circumferential surface and the upper surface to the outer surface of the support 31 and the bottom surface of the flange portion 32, respectively, and the N pole and the S pole are alternately arranged by the same section. The stimulus is magnetized. On the other hand, the rotor 30 is positioned so that the permanent magnet 37 is disposed at the upper side with a predetermined interval of the plurality of electromagnets 22.

The housing 50 has a predetermined space portion including a bobbin 20, a rotating body 30, and a barrel 40 therein, and a lower end thereof is detachably coupled to the base 10. In addition, the housing 50 has a through hole 53 formed on the upper side thereof so that external light and an image can be projected onto a lens (not shown) of the barrel 40, and the outer circumference of the through hole 53 is formed. Accordingly, the fixing projections 51 to which the separation preventing device 60, which will be described later, is fixed to protrude vertically. Furthermore, the housing 50 is formed with a plurality of coil indentation grooves 57 (see FIG. 4) in which a plurality of coils 23 wound around the bobbin 20 are partially recessed along the inner circumference. The bobbin 20 may be stably fixed to the base 10 to prevent rotation by the plurality of coil inlet grooves 57.

The release preventing device 60 includes a leaf spring portion 61 and a ring-shaped body (63). 5, the fixing protrusion 41 of the barrel 40 is inserted into the center of the leaf spring portion 61, and a fixing hole 65 for preventing rotation of the barrel 40 is formed, and the barrel 40 is formed. A plurality of cutouts 67 of a predetermined width and length are arranged to support the upper side of the elastic member. The ring-shaped body 63 is bent downward along the outer circumference of the leaf spring portion 61 and detachably coupled to the fixing protrusion 51 of the housing 50. On the other hand, the departure prevention tool 60 is stably gripped by the upper end of the fixing protrusion 51 of the housing 50 and the upper bottom of the cap 70. In addition, the departure prevention tool 60 serves to limit the maximum moving distance of the barrel 40 and prevent the barrel 40 from being separated from the housing 60. On the other hand, the departure prevention tool 20 is provided with a disc portion 160a made of a disc shape and a pair of guide holes (161, 163) as shown in Figs. 6a and 6b. In order to prevent rotation of the separation prevention tool 160, the pair of guide protrusions 141 and 143 inserted into the pair of guide holes 161 and 163 are formed on the upper end of the barrel 40. Accordingly, since a separate elastic force is not applied to the barrel 40 during the straight reciprocation of the barrel 40, the driving force of the barrel 40 can be more smoothly performed.

The cap 70 has a through hole 73 having a diameter larger than the diameter of the barrel 40 so that the upper portion of the barrel 40 can penetrate at the center thereof, and is detachably coupled to the upper side of the housing 50.

Referring to Figures 7a to 7c the operation sequence of the automatic focusing apparatus according to the first embodiment of the present invention configured as described above is as follows.

First, the initial position of the rotating body 30 is the S pole which is the same magnetic pole facing the center of a pair of electromagnets 22a, 22b facing each other around the bobbin 20 among the six electromagnets 22a-22f. It is set at a position distorted at an angle of 15 ° to one side with respect to the center.

In this initial state, in order to linearly drive the barrel 40 in one direction by rotating the rotating body 30 screwed with the barrel 40, a current is generated to generate a magnetic field of N poles in the pair of electromagnets 22a and 22b. When applied, the center of the S pole of the permanent magnet 37 spaced apart from the pair of electromagnets 22a and 22b by 15 ° in the counterclockwise direction rotates 15 ° in the clockwise direction, and as shown in FIG. 7B, the pair of electromagnets 22a , 22b).

Subsequently, when the current applied to the pair of electromagnets 22a and 22b is interrupted and the current is applied to the other pair of electromagnets 22c and 22d adjacent to the pair of electromagnets 22a and 22b to generate a S-pole magnetic field, Again, the center of the N pole of the permanent magnet 37 is turned 15 degrees clockwise, and as shown in Fig. 7C, it is positioned at the center of the pair of electromagnets 22c and 22d.

In this state, when the current is interrupted by the pair of electromagnets 22c and 22d and the current is applied to the pair of electromagnets 22e and 22f to generate the N pole magnetic field, the permanent magnet 37 The center of the S pole is rotated 15 degrees clockwise, and as shown in FIG. 7A, it is positioned at the center of the pair of electromagnets 22e and 22f.

In this way, when a pair of currents are sequentially applied to the six electromagnets 22a to 22f, the barrel 40 is linearly driven in one direction along the axial direction of the barrel 40 by the rotating body 30 rotating in one direction. do. On the other hand, the operation of driving the barrel 40 in the reverse direction can be implemented by applying a current to the six electromagnets 22a to 22f to rotate the rotating body 30 counterclockwise.

In the above, the initial state has been described as being set at a position that is rotated at an angle of 15 ° to one side with respect to the center of the S pole of the permanent magnet 37 which is the same magnetic pole facing each other with the centers of the pair of electromagnets 22a and 22b. In the initial state as shown in FIG. 7A, when a current is applied to the pair of electromagnets 22c and 22d to form a magnetic field first, the center of the pair of electromagnets 22c and 22d is N of the permanent magnet 37. As it is set at a position that is twisted with the center of the pole by 30 °, the electromagnets 22c, 22d; 22a, 22b; 22e, 22f are rotated by applying a current sequentially to form the same magnetic pole, that is, the S pole in this embodiment. It is of course also possible to continuously rotate the whole 30 by 30 °.

8 is a schematic plan view showing an automatic focus control apparatus for a camera according to a second embodiment of the present invention.

In the second embodiment of the present invention, the configuration of the first embodiment is the same, but as shown in FIG. 8, the permanent magnet 137 of the rotating body alternates with the north pole and the south pole, so that six poles are magnetized, and bobbins are used. There are four electromagnets 122a to 122d arranged to be spaced apart by the same angle.

Also in this case, as in the first embodiment, the initial position of the rotating body is set to 30 with respect to the center of the same magnetic pole facing each other by the center of the pair of electromagnets facing each other around the bobbin among the four electromagnets 122a to 122d. It is set at a position turned to one side at an angle, and the driving operation of the barrel 40 is made as described in the above-described first embodiment.

As in the present invention described above, the linear reciprocating driving force of the barrel can be increased by increasing the rotational force of the rotating body by the magnetic force formed by simultaneously generating a magnetic field by a pair of coils facing each other.

In addition, as the driving force of the barrel increases, the barrel is moved in a horizontal state in a balanced state without tilting when the barrel is moved, thereby enabling precise movement of the barrel. Providing a condition has the advantage of taking a good image.

While the invention has been shown and described with respect to preferred embodiments for illustrating the principles of the invention, the invention is not limited to the construction and operation as shown and described. Rather, those skilled in the art will appreciate that changes and modifications can be made to the present invention without departing from the spirit and scope of the appended claims. Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

Claims (8)

In the automatic focus control device for driving a straight reciprocating barrel installed in the camera, A base fixed in the camera and having a cylindrical protrusion formed on the upper surface of which the lower portion of the barrel is recessed; A bobbin coupled to the cylindrical protrusion of the base and having a plurality of electromagnets each of which coils are wound at positions spaced at the same angle along an outer circumference; A rotating body having a support screw screwed to the outer circumference of the barrel, and a ring-shaped permanent magnet fixedly coupled to an outer side of the support, in which N poles and S poles are alternately magnetized by the same section; A housing detachably coupled to the base and having a space portion including the bobbin, a rotating body, and a barrel in an inner side thereof, and a through hole formed to project light and an image into the barrel on an upper side thereof; A release preventing device disposed above the housing and configured to elastically support an upper side of the barrel to limit a maximum forward driving distance of the barrel and prevent the barrel from being separated from the housing; And a cap detachably coupled to the upper side of the housing, and configured to fix the release preventing opening to the upper side of the housing. The rotating body is characterized in that when the pair of electromagnets facing each other of the plurality of electromagnets are successively driven in pairs, the barrel is reciprocally driven in a straight line in the axial direction as it rotates in place by a magnetic field generated in the plurality of electromagnets. Auto focusing device for the camera. The method of claim 1, The permanent magnet of the rotating body is the N pole and the S pole alternately 8 magnetized, the bobbin consists of six electromagnets, The initial position of the rotating body is set at a position in which the centers of the pair of electromagnets facing each other with respect to the bobbin among the six electromagnets are turned to one side with a 15 ° angle with respect to the center of the same magnetic pole facing each other. Automatic focusing device. The method of claim 1, The permanent magnet of the rotating body is the N pole and the S pole alternately 8 magnetized, the bobbin consists of six electromagnets, The initial position of the rotating body is set at a position in which the centers of the pair of electromagnets facing each other around the bobbin among the six electromagnets are turned to one side at a 30 ° angle with respect to the center of the same magnetic pole facing each other Automatic focusing device. The method of claim 1, The permanent magnet of the rotating body is the six poles are magnetized by alternating the N pole and the S pole, the electromagnet of the bobbin is made of four, The initial position of the rotating body is set at a position in which the centers of the pair of electromagnets facing each other with respect to the bobbin among the four electromagnets are turned to one side at a 30 ° angle with respect to the center of the same magnetic pole facing each other. Automatic focusing device. The method of claim 1, wherein the release prevention tool A leaf spring portion at which an upper end of the barrel is fixed; And, And a ring-shaped body extending downward in the periphery of the leaf spring portion and fixed to the upper end of the leaf spring portion. The method of claim 1, wherein the release prevention tool A disc portion having a through hole formed in the center thereof; And, And at least two guide holes formed at intervals in the disc portion. And a plurality of guide protrusions respectively inserted into the guide holes on the upper surface of the barrel to prevent rotation of the barrel when the straight reciprocating driving of the barrel is performed. The method of claim 1, The housing is an autofocus control device, characterized in that a plurality of coil indentation grooves are formed at intervals so that the coil of the plurality of electromagnets respectively recessed to prevent the rotation of the bobbin on the inner peripheral surface. The method of claim 1, The rotating body is rotatably disposed in contact with an upper end of the cylindrical projection of the base and the upper bottom of the housing, The upper end of the cylindrical projection of the base in contact with the bottom surface of the permanent magnet of the rotating body is formed with a first lube for lubricating oil is charged, And a second lubricating oil receiving groove in which lubricating oil is charged on an upper surface of the support of the rotating body in contact with the upper bottom of the housing.

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