JP3349808B2 - Optical element drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element driving apparatus, and more particularly to an optical element driving apparatus for driving an optical element holding member forward and backward by an electromagnetic actuator.

[0002]

2. Description of the Related Art Conventionally, various proposals have been made for a lens barrel incorporating an optical element driving device for driving a lens as an optical element or an image pickup element using an electromagnetic actuator such as a VCM (voice coil motor) as a driving source. Have been. For example, a lens barrel disclosed in Japanese Patent Application Laid-Open No. 4-86714 has a fixed portion provided inside the barrel for driving a lens, and a movable portion which is a part of a lens holding frame, and is formed of a magnetic material. The drive source is a VCM including the yoke portion and the coil portion. It also has a built-in position detection sensor for detecting the lens position.

As another conventional example, a lens barrel for focusing by moving an image pickup device in the optical axis direction has already been proposed. In this lens barrel, the sleeve of the imaging element holding frame is fitted into the shaft, and the holding frame is slidably held. In addition, a flexible circuit board (hereinafter, referred to as FPC) is applied as an electrical connection to a movable side for driving the imaging element of the lens barrel.

[0004]

In the above-mentioned conventional optical element driving device, etc., the magnet serving as a thrust generating source is arranged substantially vertically and horizontally symmetrically with respect to the optical axis. The center of the driving thrust is located at the center of the optical axis of the lens. However, since the lens holding member is driven with the sleeve fitted on the guide shaft serving as a fulcrum, the distance between the point of application and the fulcrum is large, and the fulcrum occurs at the fulcrum.

[0005] When there is play in the shaft and sleeve, V
The thrust of the CM causes the movable frame of the holding member to tilt about the axis. The amount of displacement in the fc (focus adjustment) direction due to this inclination differs between the center of the optical axis and the position detection sensor unit, causing hysteresis in the drive characteristics.

Further, in a conventional lens barrel that performs focusing by moving the image sensor in the optical axis direction, if the image sensor holding frame is tilted due to backlash between the shaft and the sleeve, the image pick-up caused by the tilt is generated. The eccentricity of the imaging plane of the element directly appears as image fluctuation.

Further, in the above-mentioned conventional example, when the FPC is used to make an electrical connection with the image pickup device, a smooth driving of the image pickup device is hindered by the force generated by the bending of the FPC, and in particular, the direction in which the force acts depending on the direction of movement. However, the accuracy of the forward / backward position is reduced.

[0008] The present invention was made to solve the problem described above, and its object is as much as possible to reduce the resistance to driving thrust of the optical element driving device is driven forward and backward by an electromagnetic actuator It is to provide a device capable of.

[0009]

[0010]

SUMMARY OF THE INVENTION The optical element of the present invention
The child drive device includes an optical element holding member, and an optical element holding member.
And a guide member for slidably supporting the guide in the optical axis direction.
Around the fulcrum of the optical element holding member supported by the member
To generate the opposite moment to the moment
Thrust is adjusted and the optical element holding member is electromagnetically driven.
And an electromagnetic actuator for sliding.
Optical element supported by guide member by magnetic actuator
The child holding member is driven forward and backward.

[0011]

[0012]

[0013]

[0014]

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are exploded perspective views of a lens barrel applied to the image pickup apparatus according to the first embodiment of the present invention. FIG.
FIG. 2 is a longitudinal sectional view of the lens barrel. The lens barrel of the image pickup apparatus according to the present embodiment is a zoom lens barrel having a four-group configuration, and zooming is performed by a stepper (stepping motor).
Is rotated by driving the cam ring 3 to move each lens group holding frame forward and backward. Focusing is performed by a CCD holder 14 for holding a CCD as an image pickup device.
It is performed by driving itself forward and backward by a VCM (voice coil motor) which is an electromagnetic actuator.

The lens barrel is constructed by the above-described perspective view,
As shown in a cross-sectional view and the like, an outer fixed frame 1 that is fixed to the camera main body mainly through respective fixed frames described below,
And the cam ring 3 is held via the three cam followers 22a.
A first group frame 2, which is one of lens holding frames having a so-called three-row suspension structure, which can move forward and backward by the cam grooves 3a, and cam grooves 3a, 3b, 3c, 3d for driving the respective holding frames. A rotatable cam ring 3 provided, a wave washer 4 for biasing the cam ring, and an inner fixed frame 5 fixed to the outer fixed frame 1.
And

Further, the lens barrel holds guide shafts 7, 8 for supporting the respective lens frames other than the first group frame 2 and the CCD holder 14 so as to be able to move forward and backward, and a second group lens 42. 2 is a movable lens holding frame supported by 8
Holding the group frame 9 and the third group lens 43, the guide shaft 7,
3 group frame 1 which is a movable lens holding frame supported by 8
The fourth group frame 11 is a lens holding frame that holds the 0 and 4th lens groups 44 and is supported by the guide shafts 7 and 8 so as to be able to move forward and backward.
A yoke 12 constituting a VCM which is an electromagnetic actuator for driving the CCD, the guide shafts 7 and 8, a rear fixed frame 13 supporting the yoke 12, and the guide shafts 7 and 8.
The CCD is slidably supported, holds the CCD 55 and the LPF 54, has attached thereto an LED 61 which is a light emitting element for detecting the forward / backward position, and is wound around a drive coil 14b constituting a VCM for driving itself forward / backward. A holder 14,
The LPF 54, the CCD 55, the rear cover 15 for regulating the guide shafts 7 and 8 in the axial direction, and a cam ring driving unit for driving the rotation of the cam ring and using the stepper 51 as a driving source. And a position detecting means for detecting the advancing / retreating position of the CCD holder 14, supported by the rear fixed frame 13, receiving light from the LED 61, and detecting a position of the PSD 62.

The outer fixed frame 1, the inner fixed frame 5, and the rear fixed frame 1
Reference numeral 3 denotes that the components described below are assembled and fixed integrally with screws via the respective mounting holes 1a and 5a ', 5a and 13a. The relative positioning of the frames 1 and 13 in the rotational direction during the fixing is performed by fitting the positioning pins 1b and 13b into the positioning holes 5b of the inner fixed frame 5.

The first group frame 2 is inserted into the outer fixed frame 1 such that the first group frame 2 is movable forward and backward with the rotation thereof restricted.
The rotation is regulated by a boss 23 provided coaxially with the pin 22 of the first group frame 2 in a straight guide groove 1j provided on the inner peripheral portion of the outer fixed frame 1 to restrict the rotation. Is done. Here, a roller may be supported by the pin 22 instead of the boss 23, and this may be fitted into the straight guide groove 1j. The first group frame 2 is moved forward and backward during zooming by rotating a cam ring 3 described later.

On the inner peripheral portion of the outer fixed frame 1, convex portions 1d and 1e serving as linear reference guide portions downward along the advancing and retreating directions are provided.
However, linear convex portions 1f and 1g are provided above. Further, a leaf spring 21 as an urging member is screwed to the mounting portion 1h in the upper opening 1i in the center. Even if the first group frame 2 is fitted into the projections 1d, 1e, 1f, 1g in a state where there is a fitting play required mechanically or in terms of component accuracy, the first group frame 2 is still lower. And the outer periphery thereof comes into contact with the convex portions 1d and 1e. During the zooming operation, the first group frame 2 moves forward and backward in this state, and in the normal photographing state, this contact state is always maintained, and no tilt of the first group lens 41 with respect to the lens barrel optical axis O occurs. become. When an upward external force acts on the first group frame 2, the outer periphery of the first group frame 2 has convex portions 1 f and 1 f.
It only moves slightly until it touches g.

The cam ring 3 is rotatably fitted to the inner peripheral portion of the first group frame 2, and the inner fixed frame 5 is further fitted to the inner peripheral portion of the cam ring 3. However, a corrugated washer 4 is inserted into the outer periphery of the inner fixed frame 5, and the corrugated washer 4 connects the flange 3 h of the cam ring 3 to the flange 1 c of the outer fixed frame 1.
Press so as to contact Due to this pressing force, the above 1
The group frame 2 is positioned relative to the inner and outer fixed frames 5 and 1 in the optical axis direction. Further, since the wave washer 4 is inserted in a state where the groove 4a provided on the inner periphery thereof is fitted into the convex portion 5e of the inner fixed frame 5, its rotation is regulated.

A gear portion 3i is provided along the outer periphery of the flange portion of the cam ring 3, and a drive gear 34a of a cam ring drive portion described later meshes with the gear portion 3i through a groove 1m of the fixed frame 1. And the cam ring 3 is driven by the driving unit.
Is rotated from the wide position to the tele position.

The wide position is detected by a PI (photo interrupter) 53 provided at a turning position corresponding to the wide position on the turning locus of the shielding leaf portion 3j provided on the flange portion. You. Positioning of each zooming position is performed based on the wide position. Projecting stopper 3k provided on the flange portion of cam ring 3
Is a groove 1k provided on the flange 1c of the outer fixed frame 1.
And functions as a rotation stopper at the wide end or the tele end of the cam ring 3.

There are three cam grooves 3a for the first group frame provided on the outer peripheral portion of the cam ring 3, and the cam followers 22a of the first group frame 2 are slidably fitted into each of them. The first group frame 2
The rotation of the cam ring 3 is restricted, and when the cam ring 3 rotates, it moves forward and backward in the optical axis O direction.

Further, cam grooves 3b, 3c, 3d for the second, third, and fourth group frames are provided on the inner peripheral portion of the cam ring 3, and the second, third, and fourth group frames 9, 10, 11 are provided respectively. The cam followers 9c, 10c, and 11c fixed to the slidably fit. When the cam ring 3 rotates, each of the holding frames is moved to the optical axis O.
It will move forward and backward in the direction.

The cam ring drive unit uses a stepper 51 as a drive source. The rotation of the output gear is transmitted to a drive gear 34a via a gear train, and further transmitted to a gear unit 3i of the cam ring 3. Is done.

The support structure for the guide shafts 7 and 8 includes:
In front of the guide shafts 7 and 8 (subject side) on the inner fixed frame 5
Support holes 5f and 5g for supporting the ends of
The ends of the guide shafts 7 and 8 are inserted therein, the radial direction is determined, and the optical axis direction in the subject side is regulated.

A substantially intermediate portion between the guide shafts 7 and 8 is supported by the shaft holes 13f and 13g of the rear fixing frame 13 in a state where positioning in the radial direction is performed. The positions of the shaft hole 13f and the shaft hole 13g in the optical axis direction are shifted in a convenient manner on the support structure of the lens holding frame and the CCD holder as described later, and the shaft hole 13g is set at a higher position. Forward,
That is, it is located on the subject side. After the CCD holder 14 is inserted, the rear ends (CCD side) of the guide shafts 7 and 8 are connected to the optical axis by the bottomed holes 15f and 15g of the rear cover 15 fixed to the rear fixing frame 13. The direction is regulated and held down.

The guide shafts 7, 8 slidably support the second group frame 9, the third group frame 10, and the fourth group frame 11 between the inner fixed frame 5 and the rear fixed frame 13. That is, the guide shaft 7 has a forked portion 9 f of the second group frame 9, a third group frame 10, and a shaft hole 10 of the fourth group frame 11.
f, 11f are fitted. The guide shaft 8 has a shaft hole 9g of the second group frame 9 and two forked portions 10g, 11 of the third group frame 10 and the fourth group frame 11.
g is fitted, and the frames 9, 10, 11 are slidably supported in a state of being housed inside the inner fixed frame 5.

The cam followers 9c, 1 fixed to the second, third, fourth group frames 9, 10, 11 as described above.
0c and 11c are connected to openings 5c and 5d (described later) of the inner fixed frame 5.
And slidably fit into the cam grooves 3b, 3c, 3d of the cam ring 3. Escape of the followers 9c, 10c, 11c, and the guide shafts 7, 8 and the 2, 3, 4 group frames 9,
The inner fixing frame 5 is provided with the openings 5c and 5d along the optical axis O for escape of the shaft holes 10 and 11 and the bifurcated portion. The guide shafts 7 and 8 supported by the shaft holes 13f and 13g of the frame 13 are inserted from the opposite side of the subject, that is, the CCD side, and slidably fitted. In the fitted state, the drive coil 14b
Is inserted forward through the opening 13h, and the yoke 12
Is located at a portion surrounded by the inner peripheral portion 12 b and the magnet 16. Thereafter, a rear cover 15 is attached to the rear of the rear fixed frame 13, and the guide shafts 7 and 8 are moved by the rear cover 15.
The position is restricted in the optical axis direction.

On the other hand, as described above, the fourth group frame 11 is mounted on the subject side of the rear fixed frame 13, that is, on the front side, and the length of the fourth group frame 11 in the optical axis direction is provided on the guide shaft 7 side. A relatively long shaft hole 11f and a forked portion 11g of the fourth group frame 11 having a relatively short length in the optical axis direction are fitted on the guide shaft 8 side. In addition, the shaft holes 13f of the rear fixed frame 13,
As described above, the disposition position of the shaft 13g is the shaft hole 13f in which the guide shaft 7 is inserted and the shaft hole 1f in which the guide shaft 8 is inserted.
It is located behind 3g along the optical axis direction.

When the CCD holder 14 is mounted on the guide shafts 7 and 8, the length of the holder 14 in the optical axis direction may be relatively short for holding accuracy.
f, and the shaft hole 14g, whose length in the optical axis direction needs to be relatively long for holding accuracy,
The guide shaft 8 is inserted through the guide shaft 8 supported by 3 g.

The yoke 12 constituting the VCM is formed of a magnetic material, and is fixed to the subject side of the rear fixed frame 13 through mounting holes 12a through mounting holes 13c and 13d. It is sectional drawing around the yoke part of FIG.
(A) is a cross-sectional view orthogonal to the optical axis, and (B) is the CC thereof.
It is sectional drawing. As shown in the figure, the yoke 12 has a yoke inner peripheral portion 12b, and four magnets 16 are mounted on the upper, lower, left and right opposite to the inner peripheral portion 12b. Those magnets 1
The width of 6 is about 3/5 of one side of the inner peripheral portion 12b of the yoke. However, the width is not particularly limited to this and may be an appropriate dimension that satisfies various conditions.

The upper and lower magnets 16 are attached along the horizontal scanning direction of the CCD 55,
The magnets 16 disposed on the left and right are CCDs.
55 are attached along the vertical scanning direction. Further, the magnet 16 arranged in the horizontal direction is attached to the right with respect to the optical axis O, and the magnet 16 arranged in the vertical direction is attached to the lower part with respect to the optical axis O. In this embodiment, the four magnets 16 are connected to the inner peripheral portion 1 of the yoke 12.
They are arranged symmetrically about a substantially diagonal line Lc passing through the optical axis O of 2b. The disposition state of such a magnet 16 is determined in relation to the positions of the shaft hole 14g and the forked part 14f of the holder 14 as described later. Therefore, the four magnets 16
Is not necessarily limited to the above-described arrangement.

As shown in FIG. 5 and the like, an LPF (low-pass filter) 54 and a CCD 55 are mounted on the CCD holder 14 from the rear, that is, from the CCD side. Further, the C
A drive coil 14b is provided around the outer periphery of the cylindrical portion of the CD holder 14 outside the LPF 54 mounting portion so as to surround the LPF 54.
It is wound around the bobbin of the CD holder 14.

FIG. 6A is a cross-sectional view of the vicinity of the yoke portion, showing a relative arrangement positional relationship between the yoke 12 and the guide shafts 8, 7 as viewed from the CCD side. As shown in this drawing, the fitting shaft hole 14g portion for the guide shaft 8 of the holder 14 and the forked portion 14f portion for supporting the guide shaft 7 are located in the gap at the position where the magnet 16 is provided, and the light of the yoke 12 portion is provided. It is at a lower right position and an upper left position on a substantially diagonal line Lc passing through the axis O. Therefore, the center line connecting the guide shafts 8 and 7 substantially coincides with the diagonal line Lc on the inner periphery of the yoke.

The LED 61 of the light emitting element and the PS of the light receiving element which constitute the forward / backward position detecting section (position detecting means) of the CCD 55
As shown in FIGS. 7 and 8, the arrangement state of the D (light position detecting element) 62 is arranged on the side of the center line Lc connecting the guide shafts 7 and 8, which will be described later in detail. In addition, the above CCD
The relationship between the holder 14 and the CCD 55 in the optical axis direction is shown in FIG.
As shown in a sectional view in the optical axis direction around the CCD holder in FIG. 11, on a vertical line passing through the center point 14i of the length of the sleeve 14h of the shaft hole 14g for the guide shaft of the CCD holder 14,
Generally, it is arranged so that the imaging surface 55a of the CCD 55 is located.

Further, as shown in the sectional view of FIG. 11, an FPC 56 for electrical signal connection, one end of which is fixed to the CCD 55, is mounted so as to extend in a direction substantially perpendicular to the optical axis O, and is fixed to the rear frame. It is led out from the opening 13i of 13 and is fixed near the opening 13i. then,
With the FPC 56 bent, the CCD holder 14 is
A pressing force FF for pressing in the optical axis direction is always given.

In the lens barrel of the present embodiment having the above-described structure, in particular, the optical element driving unit is further described.
The configuration, operation, and the like will be described in detail. First, a state in which thrust acts on the CCD holder 14 will be described. Since the CCD holder 14 is supported by the guide shafts 7 and 8 so as to be able to advance and retreat as described above,
The current flowing through the drive coil 14b constituting M
Thrust F on the D holder 14 in the optical axis direction (see FIG. 6B)
Occurs. The thrust F allows the CCD holder 14, and thus the CCD 55, to move forward and backward.

The point P1 where the thrust F acting as the resultant of the driving forces acting on the CCD holder 14 acts is determined by the magnet 16 shown in FIG.
As described in (A), it is arranged to be offset to the lower right with respect to the optical axis O. In addition, since they are disposed symmetrically with respect to the diagonal line Lc, the action point P1 is located on the substantially diagonal line Lc and near the fitting shaft hole 14g for the guide shaft 8 from the optical axis O. Become.

Here, the action point P1 of the driving thrust F of the VCM is specifically determined. As a conventional general example, FIG.
As shown in FIG. 3, when a magnet 16A having a length a of one side is symmetrically disposed around the optical axis O around the inner circumference 12a of the yoke, the thrust in the four directions is determined by the action point in FIG. Work on Q0 (distance b). The resultant of the four thrusts coincides with the optical axis O. Let the coordinates be (0,0). Assuming that the thrust acting at each point b at that time is f / 4, the resultant of the thrusts is f.

On the other hand, when examining the action point P1 of the resultant force F of the thrust acting on the VCM in the CDD holder 14 of the present embodiment, as shown in the magnet arrangement diagram of FIG. Assuming that the width of the yoke inner circumference 12a is a and that a × 3/5, thrusts in four directions act on the action point Q1 in the figure, and the distance is given by b or a / 5.

The coordinates of the optical axis O are (0, 0), and the center position P1 of the resultant force of each thrust is the coordinates (x, y). Considering the moment balance, the following equation is established. That is, x
Regarding the direction, (f / 4) × (3/5) × ((a / 3) −x) + (f / 4) × (3/5) × (b−x) + (f / 4) × ( 3/5) × ((a / 5) −x) = (f / 4) × (3/5) × (b + x) Therefore, the value of x is x = a / 10.

In the y direction, (f / 4) × (3/5) × (y + b) = (f / 4) × (3/5) × ((a / 5) -y) + (f / 4) × (3/5) × (by) + (f / 4) × (3/5) × (a / 5-y) Therefore, similarly, the value of y is y = a / 1.
It becomes 0.

Therefore, the displacement OP1 of the point of action of the thrust F from the optical axis O in the direction of the guide shaft 8 is the dimension a = 10 mm, b
= 6.8 mm, the shift amount OP1 = 1.6 mm.

Since the thrust F is located near the fitting shaft hole 14g as described above, compared with the arrangement structure of the magnet 16A which is not offset with respect to the optical axis O as shown in FIG.
The rotational moment acting on the shaft hole 14g serving as the fulcrum of the holder 13 is further reduced. Thus, the CCD holder 1
If the rotational moment acting on the shaft 4 is small, the "torsion" phenomenon that occurs in the guide shaft 8 and the shaft hole 14g of the holder 14 is less likely to occur, and a smooth thrust can be achieved with a small thrust.

Next, the light emitting element 61 and the PSD which constitute the forward / backward position detecting section (position detecting means) of the CCD 55 of this embodiment are used.
The arrangement state and operation of 62 will be described in detail. FIG.
FIG. 8 is a perspective view showing an arrangement state of the CCD holder 14 and the forward / backward position detecting unit. FIG. 8 is a view of the periphery of the CCD holder 14 and the forward / backward position detecting unit viewed from the CCD side. As shown in this figure, the PSD 62 has its light receiving surface 62a supported by the rear fixed frame 13 in a state where it is positioned on a line passing through the optical axis 0 and orthogonal to a line Lc connecting the centers of the guide shafts 7 and 8. ing. Although the CCD holder 14 does not necessarily need to be integrally formed, in the present embodiment, an integrally formed slit 14i is provided at a position facing the PSD 62, and furthermore, an end portion of the slit 14i is provided. LED
Reference numeral 61 is provided to be supported by the CCD holder 14.

By arranging the position detecting section as in the above-described embodiment, when the CCD holder 14 moves forward and backward with the above-described thrust F along the optical axis O, the CCD holder 14
As shown in FIG. 9, even if the CCD 55 falls down in the optical axis direction along the center line Lc by the gap of the guide shaft hole 14g, the movement amount D0 in the optical axis direction of the optical axis center of the CCD 55 due to the fall is PS
The same movement amount is detected by D62. Therefore,
The PSD 62 can accurately detect the amount of advance / retreat movement of the center of the optical axis including the amount of movement due to the tilt of the CCD holder 14.

As shown in FIG. 18, if the PSD 62A and the LED 61A of the position detecting section are disposed on the upper portion of the CCD holder 14, as shown in the sectional view of FIG.
The D holder 14 is driven by the thrust F to form a guide shaft shaft hole 14g.
When the camera falls down by the amount of backlash, the center of the optical axis 5
5a fluctuates by the movement amount D0, but the PSD of the position detector
At the position 62A, it is detected as a change in the amplified amount D1, and the position detection accuracy is reduced.

In the structure of the present embodiment, as described above, the magnet 16 is disposed substantially symmetrically with respect to the center line Lc connecting the guide shafts, and the driving thrust F acts on the center line Lc. It is considered that the CCD holder 14 rarely tilts in the direction around the line Lc. Therefore, the CCD holder 1
The falling direction of 4 is likely to fall in the direction of the optical axis along the center line Lc, and highly accurate detection is performed by arranging the position detection unit as described above. The appropriate arrangement position of the position detection unit in consideration of a force other than the driving thrust F acting on the CCD holder 14 will be described later as a modified example.

Further, in the CCD holder 14 of this embodiment, as shown in FIGS.
The center 55a of the imaging surface of the CCD 55 is located on an extension line passing through the center 14i of the 4g sleeve portion 14h in the longitudinal direction and orthogonal to the axis. When the gap between the shaft hole 14g and the shaft is d and the sleeve portion 14h is backlashed by the driving thrust F by the gap, the center 5 of the imaging plane of the CCD 55
The deviation amount δ0 between 5a and the optical axis O of the photographing lens system has a maximum value of d / 2, and is minimum in principle. The shift amount δ0 from the optical axis O has a great influence on the shake of the image screen, and in this embodiment, the shake of the image screen is suppressed.

If the CCD as shown in the state diagram of FIG.
The center 55a of the imaging plane 55 is centered on the center 14 of the sleeve 14h.
When it is disposed at a position deviated from i, the deviation δ between the center 55a of the imaging plane and the optical axis O of the photographing lens system is, when tilted in one direction, the deviation δ2 of FIG. As shown in FIG. 20, when it is inclined in the other direction, as shown in FIG. 20B, a considerably large amount .delta.1 is given, and the image shake becomes large. Further, as shown in FIG. 20D, the center 55a of the imaging plane of the CCD 55 is
Is significantly shifted from the center 14i of the
Becomes even larger.

The above-described support structure for the optical element holding member is particularly effective in a photographing element holding member. This is because in the case of holding the lens, the amount of tilt with respect to the optical axis itself has an adverse effect on coma, and therefore there is a situation that the length of the sleeve portion needs to be increased as much as possible. This is because there is no occurrence of such an aberration, and a countermeasure against screen shake may be considered as a top priority. Further, as in this embodiment, when the holding member is easily inclined with respect to the optical axis during driving,
Furthermore, it is effective.

In this embodiment, an electric signal connection FPC 56 fixed to the CCD 55 is provided so as to extend upward in a direction perpendicular to the optical axis as shown in FIG. And the pressing force F along the extension direction
Since F is given to the CCD holder 14, the shaft hole 14g of the CCD holder 14 keeps its upper surface unilaterally in contact with the guide shaft 8, as shown in FIG. Therefore,
Hysteresis of the force applied to the holder 14 as the CCD 55 moves in the optical axis direction can be reduced. In addition, as shown in FIG.
In other words, the image plane No. 5 hardly tilts with respect to the optical axis O direction.

If the FPC for electric signal connection fixed to the CCD 55 like the conventional connection structure shown in FIG.
56A is folded back into a U-shape and mounted, and the rear cover-1
If a mounting structure that secures to 5 is taken, CC
A forward pressing force always acts on the D holder 14 via the FPC 56A. And the shaft hole 1 of the CCD holder 14
4g is held inclined as shown in FIG.
In this case, the inclination accuracy of the image plane 5 with respect to the optical axis O is degraded.

The driving operation of the present lens barrel incorporating the optical element driving device described above will be described. First, when a power switch (not shown) is turned on, the stepper 51 is driven, and the cam ring 3 rotates to the wide end position which is the reset position, and the first, second, third and fourth group frames 2, 9, and 1 are rotated.
0 and 11 are each moved to the wide end position. When performing zooming, the stepper 51 is driven from the above state, the cam ring 3 is rotated, and the 1, 2, 3, 4 group frames 2, 9, 1
0 and 11 are respectively moved with zooming. Then, the drive coil 1 of the VCM which is an electromagnetic actuator
4b, the CCD holder 14 is controlled.
The CCD 55 is moved to a zoom tracking position, which is a focus position corresponding to the zooming position. That is, the CCD 55 moves every hour according to the zooming operation to maintain the in-focus state. When performing focusing, the CCD holder 14 is controlled by VCM.
To move the CCD 55 to the in-focus position.

In the lens barrel according to the present embodiment, when the point of action of the driving force F of the VCM is brought closer to the guide shaft 8, the CCD holder 14 generated between the shaft 8 and the shaft hole 14g of the holder 14 is moved. It is possible to reduce the resistance force due to the twisting and to make the driving thrust F act effectively. Further, even if the CCD holder 14 is slightly tilted when the CCD holder 14 moves forward and backward, the position detecting unit including the tilted state can be detected by the position detecting unit, and highly accurate CCD driving can be performed.

Further, the shaking of the imaging surface of the CCD 55 due to the backlash of the guide shaft shaft hole 14g of the CCD holder 14 can be reduced as much as possible. Further, the configuration is such that the load fluctuation due to the bending of the FPC 56 acting when the CCD 55 moves forward and backward is small, and the CCD holder 14 is stably supported by the guide shaft 8.

Next, the point of action of the driving thrust F in the VCM of the optical element driving device incorporated in the lens barrel of the present embodiment can be brought closer to the guide shaft 8 side than that of the above embodiment. Modification 1 will be described. FIG.
FIG. 5 is a cross-sectional view of a cross section orthogonal to the optical axis around the yoke in the VCM of the first modification. As shown in the figure, two magnets 16B are mounted on the lower and right sides facing the inner peripheral portion 12b of the yoke. The width of the magnets 16 is set to be equal to the width of the yoke inner peripheral portion 12b. The two magnets 16B are connected to the optical axis O of the inner peripheral portion 12b of the yoke 12.
It is not always necessary to arrange them symmetrically with respect to a substantially diagonal line Lc passing through the dashed line, but in this embodiment, they are arranged symmetrically.
Other structures are the same as those in the above-described embodiment.

In the VCM constructed as described above, the point of action P2 of the driving thrust is located closer to the guide shaft 8 than in the case of the above-described embodiment.
The increase in sliding resistance due to twisting during forward / backward drive of No. 4 is small, and smooth forward / backward drive is performed.

A second modified example of another VCM described below has two magnets 16C and a direction opposite to the magnets 16C so that the point of action P3 of the driving thrust is located at the center of the guide shaft 8. The two magnets 16 </ b> D magnetized are arranged on the yoke 12. FIG. 16 is a cross-sectional view of a cross section orthogonal to the optical axis around the yoke portion in the VCM of the above modification. FIG. 17 is an action diagram of thrust when FIG. 16 is viewed from a plane along the diagonal line Lc. The above two magnets 16
C has the same size, magnetizing direction, and mounting position as the magnet 16B applied in the first modified example, but the other two magnets 16D have narrow widths and are magnetized as described above. The direction is opposite to that of the magnet 16C. Also, one of the mounting positions is mounted on the upper left side in FIG. 16, and the other is mounted on the upper left side.

Accordingly, the thrusts F1 and F2 generated by the magnets 16C and 16D, respectively, as shown in FIG.
Distance L1 from the guide shaft 8 and distance L longer than L1
Act in two ways, but in alternate directions. The moment generated by the thrusts F1 and F2 is applied to the guide shaft 8.
The distances L1 and L2 and the thrusts F1 and F2 are set so as to balance the above. That is, the distance and the thrust are set so that F1 × L1 = F2 × L2 holds. In this case, the thrust F acting on the CCD 14 is represented by F = F1-F2.

According to this modified example, the moment for tilting the CCD holder 14 around the guide shaft 8 caused by the thrusts F1 and F2 generated in the VCM becomes zero.
"Kink" does not occur in the sleeve 14h, which is the shaft support portion of the CCD holder 14, and smooth advance / retreat driving with less sliding resistance is possible.

Next, C of the optical element driving device of this embodiment is
A modified example of the CD advance / retreat position detection unit (position detection means) will be described. In the above embodiment, the driving thrust F of the VCM
Only acts on the guide axis center line Lc, and the CCD holder 1
4 is tilted in the optical axis direction along the center line Lc. However, in practice, the bending force is not always required due to the bending force of the FPC 56, the frictional force of the shaft sleeve portion 14h of the CCD holder 14, or the loose fit. It cannot be limited that the vehicle falls down along the center line Lc.

In view of this, the advance / retreat position detecting section of this modification takes into account the manner in which the CCD holder
When the position of the optical axis 55 in the optical axis direction is displaced in the direction along the guide axis, a PSD which is a light position detecting element is provided at a portion opposed to a position on the CCD holder 14 which gives a displacement amount substantially the same as the displacement amount. It is to be arranged. In this case, the arrangement position of the PSD passes through the optical axis O as in the above embodiment, but is not necessarily located on an extension line orthogonal to the center line Lc. According to this modification, the amount of movement of the CCD 55 in the optical axis direction about the optical axis center is more accurately detected by the PSD with little influence of the holder 14 falling down.

[0066]

As described above, the optical element driving device of the present invention is a device for driving the optical element forward and backward by the electromagnetic actuator, and the optical element holding member slidably supported by the guide member has a sliding resistance. The electromagnetic actuator can be driven smoothly in a state of low retraction and the required thrust of the electromagnetic actuator can be suppressed low.In addition, by arranging the optical element advance / retreat position detecting means at an appropriate position, accurate It is possible to detect the forward / backward position and perform highly accurate forward / backward drive.

[Brief description of the drawings]

FIG. 1 is a part of an exploded perspective view of a lens barrel having a built-in optical element driving device according to an embodiment of the present invention.

FIG. 2 is a part of an exploded perspective view of the lens barrel shown in FIG. 1;

FIG. 3 is a part of an exploded perspective view of the lens barrel shown in FIG. 1;

FIG. 4 is a part of an exploded perspective view of the lens barrel shown in FIG. 1;

FIG. 5 is a longitudinal sectional view along the optical axis of the lens barrel of FIG. 1;

FIG. 6 is a view showing V of the optical element driving device of the lens barrel shown in FIG. 1;
It is sectional drawing around the yoke of CM, (A) is sectional drawing of the surface orthogonal to an optical axis, (B) is sectional drawing along an optical axis.

FIG. 7 is a perspective view of a position detecting unit of the optical element driving device for the lens barrel shown in FIG. 1;

FIG. 8 is a view of a position detection unit of the optical element driving device of the lens barrel in FIG. 1 as viewed from a CCD side.

FIG. 9 is a diagram illustrating a C of the optical element driving device of the lens barrel in FIG. 1;
FIG. 9 is a diagram illustrating a CCD displacement when the CD holder is tilted down by a play and a position detection state of the position detection unit PSD.

FIG. 10 is a diagram showing a displacement of an image forming surface of the CCD when the CCD holder of the optical element driving device for the lens barrel in FIG. 1 falls down.

FIG. 11 is a cross-sectional view around a CCD holder of the optical element driving device of the lens barrel in FIG. 1;

FIG. 12 is a sectional view showing an operation state of a guide shaft supporting portion of a CCD holder of the optical element driving device of the lens barrel in FIG. 1;

FIG. 13 is a diagram showing a state in which a magnet is mounted on a yoke in a VCM of a general optical element driving device.

FIG. 14 is a diagram showing a state in which a magnet of a VCM is mounted on a yoke of the optical element driving device for the lens barrel in FIG. 1;

FIG. 15 is a diagram showing a relative positional relationship between a magnet and a guide shaft showing a modification of the VCM of the optical element driving device for the lens barrel shown in FIG. 1;

FIG. 16 is a diagram showing a relative positional relationship between a magnet and a guide shaft showing another modified example of the VCM of the optical element driving device for the lens barrel shown in FIG. 1;

FIG. 17 is a diagram showing an operation state of the thrust of the VCM according to the modification of FIG. 16;

FIG. 18 is a view from the optical axis direction of a position detection unit in a conventional optical element driving device.

FIG. 19 is a view showing a difference between a displacement amount of the CCD and a detection amount of the position detection unit when the CCD holder in the optical element driving device of FIG.

20 (A), (B), (C), and (D) show the state of swinging of the CCD imaging surface when the CCD holder in the conventional optical element driving device falls down by the amount of backlash.

FIG. 21 is a longitudinal sectional view of a CCD holder in a conventional optical element driving device.

FIG. 22 is a diagram showing a state of the guide shaft support portion in a state where the CCD holder of the optical element driving device is tilted down by a play.

[Explanation of symbols]

 8 ... guide shaft (guide member) 12 ... yoke (electromagnetic actuator) 13 ... rear fixed frame (fixed mirror frame) 14 ... … CCD holder (optical element holding member) 16… Magnet (electromagnetic actuator) 16B… Magnet (electromagnetic actuator) 16C… Magnet (electromagnetic actuator) 55… ... CCD (optical element) 56 FPC (flexible circuit board) 61 LED (light-emitting element, position detecting means) 62 PSD Light receiving element, position detecting means)

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G02B 7/04 G02B 7/00 G02B 7/09

Claims (1)

(57) [Claims] An optical element holding member, a guide member that slidably supports the optical element holding member in an optical axis direction, and a moment generated around a fulcrum of the optical element holding member supported by the guide member. An optical element driving device, comprising: an electromagnetic actuator whose thrust is adjusted so as to generate a moment, and which slides an optical element holding member by electromagnetic driving.