JP2004271789A - Lens moving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens moving device by which a lens is smoothly moved without looseness. <P>SOLUTION: The lens moving device is equipped with a conversion part 14 converting rotation by a driving means 13 to linear movement by meshing with a feed screw part 11, a lens holding frame 17 coupled with the conversion part, having first and second bearing parts 18 and 19 arranged on both sides and capable of moving while holding the lens 16, and a 1st guide pin (GP) 21 sliding in contact with both guide holes 18HA and 18HB provided separately on the first bearing part and a second GP 22 sliding in contact with the guide hole 19H of the second bearing part. In the lens moving device, the first GP on which the guide hole of the first bearing part slides is formed of magnetic material, a magnet 25 is arranged separately from the first GP at the middle position of both guide holes of the first bearing part and also the inner walls of the guide holes at both ends of the first bearing part are formed of two crossing planes 18A and 18B, and the 1st GP is held to slide on the two planes by the magnetic attractive force of the magnet. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lens moving device in an image recording device such as a video camera and an electronic still camera, and is particularly suitable for moving a lens held in a lens holding frame in the lens optical axis direction without play and vibration. The present invention relates to a lens moving device.
[0002]
[Prior art]
FIG. 6 is a perspective view of a conventional lens moving device.
This lens moving device includes a stepping motor 113 which is a driving means for rotating a drive shaft 112 having a feed screw portion 111 in the forward and reverse directions, and a rotational movement of the drive means 113 which meshes with the feed screw portion 111 of the drive shaft 112. (Conversion unit) 114 that converts the light into linear movement, and two lenses 116 connected to the conversion unit 114 and coaxially arranged on both sides of the lens 116 and in the optical axis direction perpendicular to the lens surface. A lens holding frame 117 having a bearing portion 118 having round holes 118HA and 118HB and a bearing portion 119 having a long hole 119H, and a guide pin having a circular cross section in which the bearing portion 118 having the round holes 118HA and 118HB slides. A guide having a circular cross section disposed in parallel with the guide pin 121, in which the bearing portion 119 formed of the elongated hole 119H slides. It is more configuration and pin 122.
[0003]
In this manner, the lens 116 moves by a predetermined distance along the guide pins 121 and 122 held in the lens holding frame 117 and arranged in parallel with the optical axis direction in order to perform automatic image focus adjustment and image zooming.
Here, the guide pins 121 and 122 are fixedly arranged at predetermined positions on a base (not shown) for fixing the driving means 113.
[0004]
The holes 118HA and 118HB of the bearing portion 118 arranged on the side of the lens holding frame 117 connected to the rack portion 114 shown in FIG. 6 fit with a slight gap with respect to the outer diameter of the inserted guide pin 121. Round holes 118HA and 118HB.
The hole 119H of the bearing 119 disposed on the other side is suitable for the direction between the guide pins 121 and 122 relative to the outer diameter of the guide pin 122 in order to absorb the variation in the distance between the two guide pins 121 and 122. It is a long hole 119H having a large gap.
[0005]
The slight gap provided between the round holes 118HA, 118HB and the guide pin 121 may cause a difference in the thermal expansion coefficient at low temperatures especially when the lens holding frame 117 is formed of a resin material for weight reduction. It is indispensable to avoid that the fitting becomes tight and the sliding is not smooth.
[0006]
Further, with respect to the lens moving device, for example, proposals described in Patent Documents 1 and 2 have been made, but the former has a portion of an elongated hole provided with elasticity, and a guide pin is interposed and slid. In the latter, a permanent magnet is provided in the vicinity of the elongated hole, and the lens is smoothly moved by a magnetic attraction with a guide pin formed of a magnetic material.
[0007]
Further, for example, Patent Document 3 proposes a method of removing play in a direction perpendicular to the optical axis direction by hooking a torsion spring on a lens holding frame from a rack portion side. This is to remove backlash in the right angle direction.
[0008]
[Patent Document 1]
Japanese Utility Model Application Laid-Open No. 60-120413 (FIG. 4-5)
[Patent Document 2]
Japanese Utility Model Registration No. 2522108 (FIG. 2)
[Patent Document 3]
JP-A-7-140368 (FIG. 1)
[0009]
[Problems to be solved by the invention]
In order to move the lens 116 in the optical axis direction, the stepping motor 113 is driven to rotate the drive shaft 112 having the feed screw portion 111, and the rack (conversion portion) 114 connected to the lens holding frame 117 is linearly moved. At this time, the minute vibration of the feed screw portion 111 causes the lens holding frame 117 having a slight gap between the round holes 118HA, 118HB and the guide pin 121 to rattle or vibrate through the rack portion 114. Therefore, there has been a problem that the captured image fluctuates during automatic image focus adjustment or image zooming.
The looseness and vibration of the lens holding frame 117 can be reduced as the gap between the guide pin 121 and the round holes 118HA and 118HB is reduced. However, there is a problem that there is a limit in reducing the gap.
On the other hand, as the size of an image sensor (not shown) is reduced and the size of a movie provided with the image sensor is reduced, the slight vibration of the lens holding frame 117, which has not been a problem, is relatively enlarged. There was a problem that it became more noticeable as the shaking.
[0010]
Also, in the proposals described in the above-mentioned Patent Documents 1 and 2, the backlash is also absorbed, but any of them is to absorb backlash or vibration in a direction perpendicular to the optical axis direction. Since the sliding resistance between the round hole provided on the driving side bearing and the guide pin and the sliding resistance between the long hole provided on the non-driving side bearing and the guide pin become unbalanced, the lens holding frame is formed. Is not smoothly moved in the direction of the optical axis.
Further, in Japanese Patent Application Laid-Open No. H11-163, the torsion spring is pressed against the lens holding frame from the rack portion side to remove the backlash in the direction perpendicular to the moving direction of the lens holding frame. There has been a problem that the holding frame is not smoothly moved in the optical axis direction.
[0011]
Accordingly, the present invention has been made in view of such a problem, and in a lens moving device mounted on an image recording device such as a video camera, vibration of a lens held in a lens holding frame is prevented, and the lens is moved in the optical axis direction. It is an object of the present invention to provide a lens moving device capable of moving smoothly without rattling, thereby making it possible to eliminate shaking of a photographed image.
[0012]
[Means for Solving the Problems]
So, in order to solve the above problem,
The present invention
Driving means 13 for rotating a driving shaft 12 having a feed screw portion 11,
A conversion unit 14 that meshes with the feed screw unit and converts rotational movement by the driving unit into linear movement;
A lens holding frame 17 having first and second bearings 18 and 19 which are coupled to the conversion unit 14 and hold the lens 16 and are disposed on both sides thereof, and which can be moved in the optical axis direction by the driving means; ,
A first guide pin 21 having a circular cross section which slides on two guide holes 18HA, 18HB provided coaxially at a distance from the first bearing portion 18 and a guide hole 19H provided at the second bearing portion 19 is provided. And a second guide pin 22 having a circular cross section that slides in contact with the first guide pin 21 and moving the lens holding frame 17 along the first and second guide pins 21 and 22. In a lens moving device that moves the lens 16 in the optical axis direction,
The first guide pin 21 is formed of a magnetic material, and the permanent magnet 25 is disposed at an intermediate position between the two guide holes 18HA, 18HB of the first bearing portion, spaced apart from the first guide pin, and the first The inner wall portions of the guide holes to which the guide pins slide are formed by two planes 18A and 18B intersecting each other, so that the first guide pins 21 are attracted by the permanent magnet 25 and slidably contact the two planes. A lens moving device is provided.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the lens moving device in the image recording apparatus according to the present invention will be described below with reference to the drawings using a preferred embodiment.
[0014]
<Example>
FIG. 1 is a perspective view of an embodiment of the lens moving device of the present invention.
FIG. 2 is a top view of the embodiment of the lens moving device of the present invention shown in FIG. 1, FIG. 3 is a sectional view of a first bearing portion 18 of a lens holding frame 17, and FIG. 2A is a cross-sectional view of a portion AA, FIG. 2B is a cross-sectional view of a portion BB of FIG. 2, and FIG. 2C is a cross-sectional view of a portion CC of FIG.
[0015]
As shown in FIG. 1, the lens moving device of the present embodiment
A stepping motor (drive means) 13 for rotating a drive shaft 12 having a feed screw portion 11 in forward and reverse directions;
A rack section (converting section) 14 that meshes with the feed screw section 11 of the drive shaft 12 to convert the rotational movement of the driving means 13 into a linear movement;
A first bearing portion 18 coupled to the conversion portion 14, having a through portion 18C provided at the center and two-sided intersecting guide holes 18HA and 18HB provided on both sides thereof;
A lens holding frame 17 including a lens 16 and a second bearing 19 having the first bearing 18 and a long guide hole 19H on both sides of the lens 16;
A first guide pin 21 having a circular cross section disposed in parallel with the optical axis direction and slidably in contact with the two-surface crossing guide holes 18HA and 18HB of the first bearing portion 18;
A second guide pin 22 having a circular cross section disposed in parallel with the first guide pin 21 and slidably in contact with a long guide hole 19H of the second bearing portion 19;
A permanent magnet 25 with a back yoke 27 magnetically attracts the first guide pin 21 formed of a magnetic material, and moves the lens holding frame 17 along the first and second guide pins 21 and 22. Thus, the lens 16 is moved in the optical axis direction.
Here, the first and second guide pins 21 and 22 are fixedly arranged at predetermined positions on a base (not shown) for fixing the driving means 13.
[0016]
The feature of the lens moving device of the present embodiment is that the first guide pin 21 in which the coaxial two-sided intersecting guide holes 18HA and 18HB disposed on both sides of the through portion 18C provided in the center of the first bearing portion 18 slides is magnetic. A permanent magnet 25 formed of a material and attracting the first guide pin 21 is disposed at a position of the penetrating portion 18C of the first bearing portion 18 so as to be separated from the first guide pin 21 and the first guide pin 21 is formed. 21 is formed by two planes 18A and 18B intersecting the inner wall portions of the two-faced intersecting guide holes 18HA and 18HB at both ends of the first bearing portion 18 where the first bearing portion 18 slides.
[0017]
The rack section (converting section) 14 is engaged with the feed screw section 11 of the drive shaft 12, and converts rotational movement (movement) in two forward and reverse directions by the stepping motor (drive means) 13 into linear movement.
[0018]
Of the two-sided intersecting guide holes 18HA, 18HB and the long guide holes 19H provided in the first and second bearing portions 18, 19 on both sides of the lens holding frame 17 connected to the rack portion 14, the first bearing portion 18 is coaxial. The two-faced intersecting guide holes 18HA and 18HB are provided on the first guide pin 21 having a circular cross section arranged in parallel with the optical axis direction, and the long guide hole 19H provided in the second bearing portion 19 is provided with the first guide pin 21H. Each of the guide pins 21 slides on a second guide pin 22 having a circular cross section arranged in parallel with the guide pin 21.
[0019]
In this way, the lens 16 held by the lens holding frame 17 moves a predetermined distance in the optical axis direction along the first and second guide pins 21 and 22 for performing automatic image focus adjustment and image zooming.
This embodiment is provided at an intermediate position between the concave coupling portion 14A of the rack portion (converting portion) 14 and the two-face intersection guide holes 18HA, 18HB at both ends of the first bearing portion 18 of the lens holding frame 17. It is used in a state where it is connected (coupled) with a convex coupling part (not shown).
[0020]
Next, the two-face crossing guide holes 18HA and 18HB of the first bearing portion 18 will be described with reference to FIGS.
As shown in the cross-sectional views of the two-sided intersecting guide holes 18HB and 18HA in FIGS. 3A and 3C, respectively, the first bearing portion on the side connected to the rack portion (conversion portion) 14 of the lens holding frame 17 is provided. Two coplanar surfaces 18A and 18B which intersect at a substantially right angle are formed on the inner walls of the coaxial two-surface intersecting guide holes 18HA and 18HB.
The two-sided intersecting guide holes 18HA and 18HB are large enough to insert the guide pins 21.
Here, by bringing the first guide pin 21 into contact with the two planes 18A and 18B, the first guide pin 21 can be stably held.
As will be described later, the first guide pin 21 formed of a magnetic material is slid by the magnetic attraction of the permanent magnet 25 on each of the flat surfaces 18A, 18B of the two-faced intersecting guide holes 18HA, 18HB at both ends of the first bearing portion 18. In contact.
[0021]
Next, the permanent magnet 25 arranged on the first bearing portion 18 will be described with reference to FIG.
As shown in the cross-sectional view of FIG. 3B, the permanent magnet 25 with the back yoke 27 is detachably disposed on the first bearing portion 18 while being separated from the first guide pin 21.
The penetrating portion 18C is formed so as not to come into contact with the first guide pin 21 when the first guide pin 21 is inserted and arranged in the two-sided intersecting guide holes 18HA, 18HB.
[0022]
The position of the permanent magnet 25 arranged in the first bearing portion 18 is an intermediate position of the through portion 18C provided at the center of the first bearing portion 18 (the position of the portion BB in FIG. 2). The permanent magnet 25 is disposed on the side of the two plane intersecting guide holes 18HA, 18HB where the two planes 18A, 18B intersect.
[0023]
Since the first guide pin 21 is made of a magnetic material, the first guide pin 21 is slid in contact with each of the two planes 18A, 18B of the two-sided intersecting guide holes 18HA, 18HB by the magnetic attraction of the permanent magnet 25. You. The permanent magnet 25 constantly attracts the first guide pin 21 in a non-contact manner at a position (penetration portion 18C) between the two two-sided intersecting guide holes 18HA and 18HB.
The first guide pins 21 are in close contact with the two flat surfaces 18A, 18B of the two-surface intersecting guide holes 18HA, 18HB, respectively, and are in uniform sliding contact with each other.
[0024]
By adjusting the attraction force of the permanent magnet 25, the first guide pin 21 slides uniformly on the two flat surfaces 18A, 18B of the two-surface intersecting guide holes 18HA, 18HB with an appropriate pressure without any gap (FIG. 3A). , (C)).
[0025]
A method of sandwiching the first guide pin 21 with an elastic body (not shown) instead of the permanent magnet 25 is also conceivable, but sliding with the elastic body increases sliding resistance due to movement. Also, if a resin leaf spring is used to reduce the sliding resistance with the elastic body, the pressure force changes due to a temperature change.
[0026]
As described above, the permanent magnet 25 disposed in the through portion 18C of the first bearing portion 18 into which the first guide pin 21 is fitted replaces the round hole of the conventional bearing portion with the two-sided intersecting guide holes 18HA and 18HB. The first guide pin 21 made of a material is sucked in a state in which the first guide pin 21 is separated from the first guide pin 21, and intersected planes 18 A and 18 B formed on both inner walls of the two-sided intersecting guide holes 18 HA and 18 HB. Always in sliding contact.
[0027]
Next, the movement in the movement direction of the lens holding frame 17 moving along the first guide pin 21 will be described.
When the stepping motor 13 as a driving means is rotationally driven, the rack portion (conversion portion) 14 moves linearly, and the lens holding frame 17 having the first bearing portion 18 interlocked with the rack portion 14 is provided with a first guide pin 21. Move linearly along.
[0028]
As a countermeasure against the backlash in the rotation direction about the first guide pin 21 on the rack portion 14 side, it is possible to use a technique devised in the past together. No vibration occurs due to the balance.
Each of the planes 18A, 18B of the two-sided intersecting guide holes 18HA, 18HB of the first bearing portion 18 and the first guide pin 21 is viewed in a cross section orthogonal to the moving direction of the lens holding frame 17, as shown in FIGS. As shown in ()), the two orthogonal straight lines and the circle come into contact with each other, so that the two-surface intersecting guide holes 18HA, 18HB and the first guide pin 21 can be brought into close contact with each other.
[0029]
As a result, there is no gap at the time of crimping between the two-sided intersecting guide holes 18HA, 18HB of the first bearing portion 18 on the driving side and the first guide pin 21, and the lens holding frame 17 having the two-sided intersecting guide holes 18HA, 18HB is formed. Since the play in the moving direction can be eliminated, the positional accuracy can be further improved, and the movement of the lens holding frame 17 holding the lens 16 at the time of movement becomes smooth, and the rattling and vibration of the lens holding frame 17 can be reduced. Can be prevented.
[0030]
Further, since the two-surface crossing guide holes 18HA, 18HB and the first guide pin 21 can be brought into close contact with each other, the vibration rigidity (damping force) can be increased, and the lens holding the lens 16 of the lens moving device can be obtained. Resonance inherent to the holding frame 17 can be prevented.
[0031]
With respect to the vibration in the direction perpendicular to the moving direction of the lens holding frame 17, the first guide pin 21 is provided with a gap in each of the two planes 18A, 18B of the two-faced intersecting guide holes 18HA, 18HB at both ends of the first bearing portion 18. Therefore, even if there is a slight gap or play between the long guide hole 19H of the second bearing portion 19 and the second guide pin 22, the gap is centered on the first guide pin 21 due to the play. The movement and vibration of the lens holding frame 17 can be reduced to half the distance from the first guide pin 21 to the center of the lens 16 which is half the distance to the long guide hole 19H.
[0032]
Next, the magnetization of the permanent magnet 25 and its arrangement will be described with reference to the drawings.
FIG. 4 is a perspective view of a permanent magnet in the embodiment of the lens moving device of the present invention, and FIG. 5 is a diagram showing an arrangement relationship between a magnetized state of the permanent magnet and a guide pin in the embodiment of the lens moving device of the present invention. 5A is a diagram in which NS2 poles are arranged in the moving direction of the first bearing portion, and FIG. 5B is a diagram in which NS2 poles are arranged perpendicular to the moving direction of the first bearing portion.
As shown in FIG. 5A, the permanent magnet 25 is magnetized with two poles of NS in the moving direction of the first bearing portion 18 that moves along the first guide pin 21 made of a magnetic material.
[0033]
Due to the magnetic attraction between the permanent magnet 25 and the first guide pin 21, the first guide pin 21 is pressed against the two planes 18A and 18B with a uniform pressing force. In this embodiment, a permanent magnet 25 having a back yoke 27 on the back as shown in FIG. 4 is used.
[0034]
The permanent magnet 25 may be arranged so that two poles of NS are magnetized perpendicularly to the moving direction of the first bearing portion 18 (see FIG. 5B).
However, the arrangement shown in FIG. 5A in which the magnetic flux is formed in the first guide pin 21 in parallel with the moving direction of the first bearing portion 18 is better than the arrangement shown in FIG. 5B. Therefore, the first guide pin 21 can be efficiently attracted by the small permanent magnet 25. As a result, the size of the first bearing portion 18 having the permanent magnet 25 can be reduced.
[0035]
The back yoke 27 having the permanent magnet 25 is configured to be detachably fitted to the first bearing portion 18 as shown in FIG.
[0036]
As described above, the effect of the lens moving device of this embodiment is that when the lens holding frame 17 is guided by the first and second guide pins 21 and 22 and slides in the optical axis direction of the lens 16, The guide pin 21 is attracted by the permanent magnet 25, and is stably held by two intersecting planes provided in the two-face intersecting guide holes 18HA and 18HB at both ends of the first bearing portion 18 on the driving side of the lens holding frame 17. Since the lens 16 slides in a well-balanced manner in both the upper, lower, left, and right directions, the posture of the lens holding frame 17 holding the lens 16 can always be stably held. Therefore, it is possible to operate stably without the optical axis passing through the lens 16 of the lens holding frame 17 being slightly inclined or swinging back and forth and right and left during sliding.
[0037]
In addition, the lens holding frame 17 may generate resonance and generate noise due to the influence of the rotational vibration of the stepping motor 13, but in this embodiment, the two bearings of the first bearing portion 18 of the lens holding frame 17 are used. Since the guide pin 21 is slid by the suction force on the two intersecting planes 18A and 18B provided in the guide hole with a constant pressing force, resonance inherent in the lens holding frame 17 holding the lens 16 can be suppressed. I can do it.
As described above, the present embodiment can provide a lens moving device suitable for miniaturization of an image recording apparatus to be mounted, because it does not use expensive materials and components, is low cost, and does not take up space.
[0038]
【The invention's effect】
As described above, according to the lens moving device of the present invention, the first guide pin is formed of a magnetic material, and the permanent magnet is positioned at an intermediate position between two guide holes provided separately from the first bearing portion. The first guide pin is disposed at a distance from the first guide pin, and the inner wall portions of the guide holes with which the first guide pin slides are formed on two planes intersecting each other, and the first guide pin is attracted by the permanent magnet. So that the two planes intersecting each other are slid in contact with each other, so that in a lens moving device mounted on an image recording device such as a video camera or an electronic still camera, vibration of the lens held by the lens holding frame is prevented. The lens can be moved smoothly without rattling in the direction of the optical axis, thereby providing an effect of providing a lens moving device in which the captured image is not shaken.
[0039]
Further, according to the lens moving device of the present invention, there is an effect that resonance inherent to the lens holding frame holding the lens of the lens moving device can be prevented.
Further, according to the lens moving device of the present invention, each of two intersecting planes of the two guide holes provided separately from each other in the first bearing portion is slidably contacted with the first guide pin with an equal pressing force. This has the effect that the sliding of the lens holding frame in the moving direction can be made smooth.
[0040]
In addition, an image recording device such as a video camera or an electronic still camera equipped with the lens moving device of the present invention can prevent the vibration of the lens held in the lens holding frame, so that the shake of the captured image due to the occurrence of rattling vibration of the lens can be reduced. There is an effect that it can be made inconspicuous.
[0041]
Further, according to the lens moving device of the present invention, it is possible to provide a lens moving device suitable for miniaturization of an image recording apparatus to be mounted, since it is low cost without using expensive materials and parts and does not take up space.
[Brief description of the drawings]
FIG. 1 is a perspective view of an embodiment of a lens moving device according to the present invention.
FIG. 2 is a top view of the embodiment of the lens moving device of the present invention shown in FIG.
3A and 3B are cross-sectional views of a first bearing portion of the lens holding frame. FIG. 3A is a cross-sectional view of a portion AA in FIG. 2, and FIG. 3B is a cross-sectional view of a portion BB in FIG. FIG. 2C and FIG. 2C are cross-sectional views taken along the line CC of FIG.
FIG. 4 is a perspective view of a permanent magnet in the embodiment of the lens moving device of the present invention.
FIGS. 5A and 5B are diagrams showing the relationship between the magnetized state of the permanent magnet and the arrangement of the guide pins in the embodiment of the lens moving device of the present invention. FIG. 5A shows NS2 poles in the moving direction of the first bearing. FIG. 2B is a diagram in which NS2 poles are arranged perpendicular to the moving direction of the first bearing.
FIG. 6 is a perspective view of a conventional lens moving device.
[Explanation of symbols]
11 feed screw part 12 drive shaft 13 drive means (stepping motor)
14 conversion part (rack part)
14A Concave type coupling part 16 Lens 17 Lens holding frame 18 First bearing part 18A, 18B Plane 18C forming the inner wall of each two-sided intersecting guide hole 18HA, 18HB Penetrating parts 18HA, 18HB Guide hole (two-sided intersecting guide hole)
19 Second bearing 19H Guide hole (long guide hole)
21 1st guide pin (magnetic material)
22 second guide pin 25 permanent magnet 27 back yoke

Claims (1)

Drive means for rotating a drive shaft having a feed screw portion,
A conversion unit that meshes with the feed screw unit and converts rotational movement by the driving unit into linear movement;
A lens holding frame coupled to the conversion unit, holding first and second bearings arranged on both sides while holding the lens, and movable in the optical axis direction by the driving unit;
A first guide pin having a circular cross section which slides on two guide holes provided coaxially spaced apart from the first bearing portion and a circular cross section which slides on a guide hole provided on the second bearing portion. A second guide pin parallel to the first guide pin, and a lens moving device that moves the lens in the optical axis direction by moving the lens holding frame along the first and second guide pins.
The first guide pin is formed of a magnetic material, and a permanent magnet is arranged at an intermediate position between the two guide holes of the first bearing portion so as to be separated from the first guide pin, and the first guide pin slides. An inner wall portion of the guide hole is formed by two planes intersecting each other, and the first guide pin is attracted by the permanent magnet and slidably contacts the two planes.

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