JP2016173509A - Rack mechanism and lens drive unit having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rack mechanism rarely causing tooth jump or biting and a lens drive unit having the same.SOLUTION: The rack mechanism has a rack member which engages with a feed screw and a facing teeth member which faces to the rack member being interposed by the feed screw which is displaceable with respect to the rack member. The rack member has a shaft part which is connected to a holding member for holding a lens. The facing teeth member has an engagement part which engages with the shaft part. The rack member and the facing teeth member are rotatable on the shaft part.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a rack mechanism and a lens driving device having the same.

  2. Description of the Related Art Conventionally, a lens driving device in an electronic camera typified by a video camera or a digital still camera using an image sensor has a motor with a feed screw (lead screw) whose longitudinal direction is directed to the optical axis direction and a feed screw. And a meshing rack mechanism. As the feed screw rotates, the rack mechanism moves in the longitudinal direction (optical axis direction) of the feed screw, so that the holding member that holds the lens and is engaged with the rack mechanism is linearly driven in the optical axis direction. It is common.

  Patent Document 1 discloses a structure in which two rack members that are urged by a feed screw constituting a rack mechanism are urged so as to sandwich the feed screw.

JP-A-4-240609

  In the structure disclosed in Patent Document 1, when the lens driving device receives an impact, a so-called tooth skipping (hereinafter referred to as “tooth skipping”) in which the meshing position of the rack mechanism and the feed screw is displaced may occur. Also, the rack member may bite into the feed screw, so-called biting (hereinafter referred to as “biting”). When the tooth jump occurs, the position on the feed screw of the rack mechanism shifts, and when the bite occurs, a load is applied to the feed screw, causing a malfunction.

  An object of the present invention is to provide a rack mechanism that hardly causes tooth skipping and biting and a lens driving device having the rack mechanism.

  To achieve the object of the present invention, the present invention provides a rack member that meshes with a feed screw, a first elastic member that biases the rack member against the feed screw, and the feed screw with respect to the rack member. A rack mechanism having opposed tooth members that are opposed to each other and are displaceable with respect to the rack member, and a second elastic member that urges the opposed tooth members in a direction approaching the feed screw, The rack member has a shaft portion connected to a holding member that holds a lens, the counter tooth member has a fitting portion into which the shaft portion is fitted, and the rack member and the counter tooth member are It is possible to rotate around the axis of the shaft portion.

  According to the present invention, it is possible to provide a rack mechanism that hardly causes tooth skipping and biting and a lens driving device having the rack mechanism.

1 is a block diagram of an image pickup apparatus in Embodiment 1. FIG. 1 is a perspective view of a lens driving device and the like in Embodiment 1. FIG. The side view of a feed screw and a rack mechanism in Example 1. The side view of the rack mechanism in Example 1. FIG. FIG. 3 is a perspective view of a rack mechanism in the first embodiment. FIG. 3 is a perspective view of a rack mechanism in the first embodiment. FIG. 3 is an exploded perspective view of the rack mechanism in the first embodiment. FIG. 3 is an exploded perspective view of the rack mechanism in the first embodiment. 1 is a perspective view of a lens driving device and the like in Embodiment 1. FIG. The side view of the rack mechanism in Example 2. FIG. The perspective view of the rack mechanism in Example 2. FIG. The perspective view of the rack mechanism in Example 2. FIG. FIG. 6 is an exploded perspective view of a rack mechanism in Embodiment 2. FIG. 6 is an exploded perspective view of a rack mechanism in Embodiment 2.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram of an imaging apparatus according to an embodiment of the present invention.

  Hereinafter, with reference to FIG. 1, an image pickup apparatus (optical apparatus) having a lens driving device in Embodiment 1 of the present invention will be described.

  FIG. 1 is a block diagram of the imaging apparatus of the present embodiment.

  L1 is a first lens unit having a fixed positive refractive power. L2 is a second lens unit (magnification lens) having a negative refractive power that performs a magnification operation by moving in the optical axis direction. L3 is a third lens unit having a fixed positive refractive power. L4 is a fourth lens group (focus lens) having a positive refractive power that performs focusing (focusing operation) by moving in the optical axis direction.

  Reference numeral 1 denotes a front lens barrel that holds the first lens unit L1, 2 denotes a first holding member (holding member) that holds the second lens unit L2, and 3 denotes a fixing member that holds the third lens unit L3. It is. Reference numeral 4 denotes a second holding member (holding member) that holds the fourth lens unit L4.

  Reference numeral 30 denotes an image pickup means including an image pickup element such as a CCD or CMOS, or a filter such as a low-pass filter or an infrared cut filter. The imaging means 30 is held by a rear barrel (not shown). Reference numeral 31 denotes a camera signal processing circuit. The camera signal processing circuit 31 performs predetermined amplification, gamma correction, and the like on the output of the imaging unit 30. 32 is a microcomputer. The microcomputer 32 takes in many signals and performs signal processing. Further, the microcomputer 32 outputs a large number of signals in accordance with the input signal, and controls the optical device.

  Reference numeral 33 denotes recording means. The recording unit 33 records the image signal processed by the microcomputer 32 and other recording conditions.

  Reference numeral 50 denotes a zoom switch capable of instructing zooming. Reference numeral 51 denotes a focus switch capable of instructing a focusing operation by manual operation. 52 is a power switch.

  The first holding member 2 is supported by guide bars 101 and 102 (FIG. 2) so as to be movable in the optical axis direction. The second holding member 4 is supported by two guide bars (not shown) so as to be movable in the optical axis direction.

  Reference numeral 5 denotes an aperture device that changes the aperture diameter of the optical system. The aperture device 5 is a so-called guillotine type aperture device in which the aperture diameter is changed by moving two aperture blades in opposite directions by the drive unit 6.

  Reference numeral 34 denotes an aperture sensor circuit. The aperture sensor circuit 34 detects the rotational position of the drive magnet of the aperture drive unit 6 with a Hall element.

  The imaging signal is output to the camera signal processing circuit 31 by the imaging means 30. A signal subjected to predetermined amplification, gamma correction, and the like by the camera signal processing circuit 31 is output to the microcomputer 32. The microcomputer 32 outputs an aperture drive signal to the aperture drive circuit 37 in accordance with the input signal from the camera signal processing circuit 31 and the input signal such as the rotation amount of the aperture drive unit from the aperture sensor circuit 34 to adjust the light amount. .

  Reference numeral 8 denotes a zoom motor as an actuator (driving means) that rotationally drives the feed screw 8a around the axis in the longitudinal direction of the feed screw 8a. The feed screw 8a is coaxial with the rotor of the zoom motor and is arranged in parallel with the optical axis (so that the longitudinal direction coincides with the optical axis direction). A rack member 7 connected to the first holding member 2 is engaged with the feed screw 8a, whereby the first holding member 2 is moved in the longitudinal direction of the feed screw 8a (optical axis) by the rotation of the feed screw 8a. Direction).

  Reference numeral 9 denotes a zoom initial position sensor (photo interrupter). The zoom initial position sensor 9 electrically detects the switching between light shielding and light transmission due to movement of a light shielding portion (not shown) formed on the first holding member 2 in the optical axis direction. The optical axis direction reference position is detected.

  When the power switch 52 is turned on, the zoom motor 8 receives a drive signal from the zoom drive circuit 35 based on a signal from the microcomputer 32. The zoom initial position sensor 9 detects the initial position, and the first holding member 2 moves to a predetermined position and stands by. The zoom motor 8 is subjected to position control corresponding to the operation of the zoom switch 50 by the number of steps from the detected initial position. When the zoom switch 50 is operated, the microcomputer 32 determines in which direction the movement direction is operated, and the zoom operation is performed.

  Reference numeral 11 denotes a focus motor as an actuator which is a driving means for moving the fourth lens unit L4 in the optical axis direction to perform a focusing operation. The feed screw 11a meshes with a rack member 10 installed on a second holding member 4 that is guided and held so as to freely move in the optical axis direction. The rotation of the rotor causes the second holding member 4 to move to the optical axis. Move in the direction. The feed screw 11a is arranged coaxially with the rotating rotor constituting the focus motor and parallel to the optical axis.

  Reference numeral 12 denotes a focus initial position sensor (photo interrupter). The zoom initial position sensor 12 electrically detects the switching between light shielding and light transmission due to movement in the optical axis direction of a light shielding portion (not shown) formed on the second holding member 4, and the second holding member 4 The optical axis direction reference position is detected.

  When the power switch 52 is turned on, the focus motor 11 receives a drive signal from the focus drive circuit 36 by a signal from the microcomputer 32. Then, the initial position is detected by the focus initial position sensor 12, and the second holding member 4 moves to a predetermined position and stands by. The focus motor 11 is subjected to position control corresponding to the operation of the zoom switch 50 and the focus switch 51 by the number of steps from the initial position.

  In the auto focus control, the focus drive circuit 36 energizes the focus motor 11 in accordance with an input signal from the microcomputer 32, and the fourth lens group L4 is driven in the optical axis direction.

  Next, the rack mechanism according to the first embodiment of the present invention will be described with reference to FIGS. As will be described later, the rack mechanism includes a rack member 7, a counter tooth portion 40, a first elastic member 41, a second elastic member 42, and a third elastic member 44.

  The first holding member 2 that holds the second lens group L2 is supported by the sleeve portion 2a, the anti-rotation engaging recess 2b, and the guide bars 101 and 102 so as to be movable in the optical axis direction (FIG. 2).

  7 is a rack member provided with a meshing portion 7a that meshes with the feed screw 8a (FIG. 3). 40 is a tooth skip suppression tooth member (opposite tooth member) provided with a tooth skip suppression tooth (opposite tooth portion) 40a for suppressing tooth skip due to impact (FIG. 3). Reference numeral 41 denotes a first member attached to a cylindrical portion (shaft portion) 7c whose axis is an XX axis of the rack member 7 (an axis connecting the shaft hole portions 2c and 2d, which is preferably parallel to the optical axis). 1 is a torsion coil spring as an elastic member (FIG. 4).

  Reference numeral 42 denotes a torsion coil spring as a second elastic member attached to a cylindrical portion (shaft portion) 7d having the XX axis as an axis of the rack member 7 (FIG. 4). Reference numeral 44 denotes a coil spring as a third elastic member attached to a cylindrical portion (shaft portion) 7c and a rectangular column portion 7e with the XX axis as an axis of the rack member 7 (FIG. 4). The cylindrical portion (shaft portion) 7 c of the rack member 7 is fitted with the shaft hole portion (fitting portion) 40 c of the opposing tooth member 40, and the opposing tooth member 40 is XX with respect to the rack member 7. It engages so as to be rotatable (displaceable) around the axis (FIGS. 4 and 7).

  Tapered portions (shaft portions) 7b and square pillar portions (shaft portions) 7e of the rack member 7 are fitted in the shaft hole portions 2c and 2d of the first holding member 2, and the rack member 7 is the first member. The holding member 2 is engaged with the holding member 2 so as to be rotatable around the XX axis (FIGS. 5 and 7).

  The rack member 7 and the opposing tooth member 40 can rotate around the shafts 7b, 7c, 7d, and 7e (FIGS. 4 to 7).

  The third elastic member 44 (FIG. 4) applies an urging force (optical axis urging force) 44a in the optical axis direction (FIG. 5). Thereby, the contact part (second contact part) 40e (FIG. 8) of the opposing tooth member 40 in the optical axis direction and the contact part (first part of the rack member 7 in the optical axis direction) that can contact each other. 7h (FIG. 7) abuts in the optical axis direction. Thereby, the phase shift of the main tooth part (meshing part) 7a and the opposing tooth part 40a due to impact is suppressed.

  The urging force 44 a in the optical axis direction is also used when the taper portion (shaft portion) 7 b of the rack member 7 is urged toward the shaft hole portion 2 c of the first holding member 2. Thereby, backlash when the first holding member 2 moves in the optical axis direction is suppressed (FIG. 5).

  The opposing tooth member 40 generates an urging force (axial urging force) 42 b (FIG. 6) around the XX axis by the second elastic member 42. Thereby, the contact portion (sixth contact portion) 40b (FIG. 8) around the XX axis of the opposing tooth member 40 and the contact portion (fifth contact) around the XX axis of the rack member 7 are obtained. 7f (FIG. 7) abuts around the XX axis. Thereby, in the normal state which does not receive an impact, the opposing tooth part 40a can be made into a non-contact state to the feed screw 8a (FIG. 3).

  The around-axis biasing force 42b is set so as to be larger than the impact force 43 in the direction away from the feed screw 8a, which is applied to the opposing tooth member 40 by an impact (first impact) of a predetermined impact force or less.

  As a result, the meshing portion 7a of the rack member 7 is moved around the XX axis so as to be separated from the feed screw 8a due to a load generated in the longitudinal direction (optical axis direction) of the feed screw 8a in response to the first impact. In this case, the opposing tooth portion 40a meshes with the feed screw 8a. Thereby, the position shift by tooth skip is suppressed. Further, when the impact force 43 in the direction away from the feed screw 8a applied to the opposing tooth member 40 by an impact (second impact) larger than a predetermined impact force is larger than the axial biasing force 42b, the opposing teeth The member 40 also moves around the XX axis so as to be separated from the feed screw 8a. Thereby, the biting to the feed screw 8a of the opposing tooth part 40a and the meshing part 7a is suppressed.

  In response to the second impact, a force opposite to the optical axis direction biasing force 44 a may be applied to the opposing tooth member 40. At this time, the opposing tooth member 40 tends to separate in the direction of the force opposite to the optical axis direction biasing force 44a in the longitudinal direction (optical axis direction) of the feed screw 8a. However, the optical axis direction contact portion (fourth contact portion) 40f of the opposing tooth member 40 contacts the optical axis direction contact portion (third contact portion) 7i of the rack member 7. Thereby, the phase shift of the meshing part 7a and the opposing tooth part 40a is suppressed. The distance between the third contact part 7i and the fourth contact part 40f in the state of being biased by the optical axis direction biasing force 44a is preferably narrower than the thread spacing of the feed screw 8a. The third contact part 7i and the fourth contact part 40f can be prevented before the opposing tooth part a of the opposing tooth member 40 exceeds the thread when receiving the second impact, thereby preventing phase shift. Because.

  In the temporarily assembled state of the first holding member 2, an urging force (axis urging force) 41 b around the XX axis is generated in the rack member 7 by the first elastic member 41. Thereby, the rotation restricting portion 7g of the rack member 7 is brought into contact with the stopper portion 2e of the first holding member 2 (FIG. 9).

  When the zoom motor 8 is incorporated, the meshing portion 7a meshes with the feed screw 8a, and the rotation restricting portion 7g of the rack member 7 is detached from the stopper portion 2e. As a result, the engaging portion 7a is urged by the urging force 41b around the shaft so as to engage with the feed screw 8a (FIG. 9).

  The first elastic member 41 that generates the urging force 41b around the axis and the second elastic member 42 that generates the urging force 42b around the axis by making the rotation axis of the rack member 7 coincide with the rotation axis of the opposing tooth member 40. As described above, the same type of elastic member having different elastic force can be used. Therefore, it is easy to set the amount of movement of the meshing portion 7a away from the feed screw 8a and the amount of movement of the opposing tooth portion 40a approaching the feed screw 8a when receiving an impact, and it is difficult to cause tooth skipping and biting.

  The same type of elastic member is preferably a torsion coil spring having the same diameter. When a leaf spring is used as the elastic member, the spring constant needs to be set by the length and thickness of the leaf spring. Therefore, an error is likely to occur in the urging force around the axis 42b, and it becomes difficult to set the tooth skipping strength (indicating an impact that does not cause tooth skipping). Further, it is necessary to separately provide a plate spring fixing member, which increases the number of parts in the rack mechanism and increases the size of the rack mechanism.

  When the torsion coil spring is used as in the first embodiment, the second elastic member 42 and the first elastic member 41 can be attached to the cylindrical portions 7d and 40d with the XX axis as an axis, respectively. Therefore, it is not necessary to provide a fixing member, and the rack mechanism is not increased in size. Moreover, it becomes easy to set the spring constant, and the shape and dimensions do not change greatly by changing the spring constant. Therefore, setting of the tooth skipping strength is relatively easy.

  Hereinafter, the rack mechanism according to the second embodiment of the present invention will be described with reference to FIGS. As will be described later, the rack mechanism includes a rack member 7, a counter tooth portion 40, a first elastic member 41, and a second elastic member 42.

  In the first embodiment, the biasing force 41b around the axis is applied by the first elastic member 41, and the biasing force 44a in the optical axis direction is applied by the third elastic member 44. On the other hand, in Example 2, both the urging force around the axis and the urging force in the optical axis direction are applied by the first elastic member 41. That is, the first elastic member 41 of the second embodiment also serves as the function (biasing in the optical axis direction) of the third elastic member 44 of the first embodiment.

  The first elastic member 41 (FIG. 10) applies a biasing force (optical axis biasing force) 41a in the optical axis direction (FIG. 11). Thereby, the contact portion (second contact portion) 40e (FIG. 14) of the opposing tooth member 40 in the optical axis direction and the contact portion (first contact portion) 7h of the rack member 7 in the optical axis direction are formed. (FIG. 13) contact each other in the optical axis direction. Thereby, the phase shift of the meshing part 7a and the opposing tooth part 40a by an impact is suppressed.

  The optical axis direction biasing force 41 a is also used when the taper portion (shaft portion) 7 b of the rack member 7 is biased to the shaft hole portion 2 c of the first holding member 2. Thereby, backlash when the first holding member 2 moves in the optical axis direction is suppressed (FIG. 11).

  In the second embodiment, the function of the third elastic member 44 of the first embodiment is also used. However, the second elastic member 42 may also have the function of the third elastic member 44 of the first embodiment.

  In the first and second embodiments, the torsion coil spring is used as the first elastic member 41 and the second elastic member 42, but other springs (plate springs or the like) may be used.

  In the first and second embodiments, the retracting structure of the rack mechanism in the driving unit of the variable power lens has been described.

  As mentioned above, although the preferable Example of this invention was described, this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary.

7, 10 Rack member 7a This tooth part (meshing part)
7h Optical axis direction contact portion (first contact portion)
7i Optical axis direction contact portion (third contact portion)
40 Tooth skip suppression tooth member (opposite tooth member)
40a Tooth skip suppression tooth (opposite tooth)
40e Optical axis direction contact portion (second contact portion)
40f Optical axis direction contact portion (fourth contact portion)
41 1st elastic member 42 2nd elastic member

Claims (9)

A rack member meshing with the feed screw;
A first elastic member for urging the rack member against the feed screw;
Opposing tooth members that face the rack member with the feed screw interposed therebetween and are displaceable with respect to the rack member;
A rack mechanism having a second elastic member that urges the opposing tooth member in a direction approaching the feed screw,
The rack member has a shaft portion connected to a holding member that holds a lens,
The opposed tooth member has a fitting portion into which the shaft portion is fitted,
The rack mechanism, wherein the rack member and the opposing tooth member are rotatable around the axis of the shaft portion.   The rack member has a first abutting portion and a third abutting portion in the longitudinal direction of the feed screw, and the opposing tooth portion is arranged in the longitudinal direction of the feed screw. 2. The rack mechanism according to claim 1, further comprising: a second abutting portion capable of abutting against the first abutting portion; and a fourth abutting portion capable of abutting against the third abutting portion.   The rack mechanism according to claim 1 or 2, wherein the counter tooth member contacts the feed screw when the rack member does not contact the feed screw.   The rack member and the opposing tooth member are in contact with each other so that the opposing tooth member does not contact the feed screw when the rack member abuts on the feed screw. The rack mechanism according to any one of claims 1 to 3, further comprising a contact portion.   In the first contact portion and the second contact portion, or the third contact portion and the fourth contact portion, the rack member does not contact the feed screw, and the opposing tooth member The rack mechanism according to any one of claims 1 to 4, wherein the rack mechanism is brought into contact with the feed screw.   The rack mechanism according to claim 2, further comprising a third elastic member that urges the rack member and the opposing tooth member in a longitudinal direction of the feed screw.   The rack mechanism according to claim 6, wherein the first elastic member and the second elastic member are torsion coil springs, and the third elastic member is a coil spring.   A lens driving device comprising the rack mechanism according to claim 1.   An optical apparatus comprising the lens driving device according to claim 8.

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