JP2019215387A - Optical device and imaging apparatus - Google Patents

Abstract

To reduce the load of a driving part when moving an optical element by using a cam plate.SOLUTION: An optical device 100 includes an optical element 2 which can be moved in a first direction Z, a cam member 20 which is moved in a second direction Y orthogonal to the first direction, to move the optical element in the first direction, a guide member 21 which guides the cam member in the second direction, a driving part 16 which moves the cam member in the second direction, and an energizing member 19 which energizes the cam member. The energizing member is provided so as to energize the cam member upward, when the second direction is a vertical direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical device for moving a movable optical element by using a cam member (cam plate) that moves straight in a direction orthogonal to the moving direction of the optical element.

  In such an optical device as described above, a general configuration is such that a cam plate is supported by a guide mechanism that guides the cam plate in the direction of linear movement, and an end of the cam plate is engaged with a driving unit that drives the cam plate. Patent Literature 1 discloses that a straight movement of a cam plate is guided by engaging three cam grooves provided on a cam plate for moving a lens with three cam pins provided on a fixed portion, and furthermore, the cam plate has A structure for engaging the end with the drive is disclosed.

JP 2008-26827 A

  However, in the structure disclosed in Patent Literature 1, the cam plate and the lens are engaged at a position apart from the engagement portion between the cam plate and the drive unit. Is big. For this reason, the load on the driving unit increases, and as a result, the driving unit increases in size, and as a result, the optical device increases in size.

  The present invention provides a small-sized optical device that reduces the load on a driving unit when moving an optical element using a cam plate.

  An optical device according to one aspect of the present invention moves an optical element in a first direction by moving in an optical element movable in a first direction and in a second direction orthogonal to the first direction. A cam member, a guide member for guiding the cam member in the second direction, a drive unit for moving the cam member in the second direction, and an urging member for urging the cam member are provided. The urging member is provided so as to urge the cam member upward in a state where the second direction is the vertical direction.

  Note that an imaging device having the above-described optical device and imaging device also constitutes another aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the load of the drive part of the optical device using the cam member which moves in the direction orthogonal to the moving direction of the optical element can be reduced, and the miniaturization of the optical device can be realized.

FIG. 2 is a sectional view of a lens barrel according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a lens driving mechanism of a lens barrel (normal posture) according to the embodiment. FIG. 4 is a diagram illustrating a lens driving mechanism of a lens barrel (WIDE end) of the embodiment. FIG. 4 is a diagram showing a lens driving mechanism of a lens barrel (TELE end) of the embodiment. FIG. 4 is a diagram illustrating a lens driving mechanism of a lens barrel (a depression angle posture) according to the embodiment. FIG. 4 is a diagram illustrating a lens driving mechanism of a lens barrel (downward posture) according to the embodiment. FIG. 2 is a front perspective view of the lens barrel (normal posture) of the embodiment. FIG. 4 is a rear front perspective view of the lens barrel (normal posture) of the embodiment. FIG. 7 is a diagram illustrating a lens driving mechanism in a lens barrel (normal posture and depression posture) as a comparative example. FIG. 8 is a diagram illustrating a lens driving mechanism in a lens barrel (downward posture) as the comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIGS. 1, 7, and 8 show the configuration of an image pickup apparatus including a lens barrel 100 as an optical apparatus according to an embodiment of the present invention. The lens barrel 100 has an imaging optical system. The imaging optical system includes a first lens 1, a second lens (optical element) 2, and a third lens in order from the object side to the image side in an optical axis direction (first direction) Z in which the optical axis A extends. 3 and a fourth lens 4. The imaging optical system focuses light from an object (subject) (not shown) on the image sensor 5 disposed closer to the image than the imaging optical system.

  The imaging element 5 captures (photoelectric conversion) an object image as an optical image formed on the imaging surface. The video processing unit (not shown) generates a video signal by performing various types of video processing on the imaging signal output from the imaging element 5, and outputs the video signal to the outside of the imaging device. The imaging device 5 is fixed to the housing 11 of the lens barrel 100 via the imaging device holding member 12.

  The first lens 1 is held by a first lens frame 7, and the first lens frame 7 is fixed to a housing 11. The second lens 2 is a lens that moves in the optical axis direction Z to change the magnification, and is held by the second lens frame 8. The second lens frame 8 is movably engaged with the second lens guide bar 13a in the optical axis direction Z to be guided in the optical axis direction Z, and is also moved in the optical axis direction Z by the second lens rotation stopper bar 13b. As a result, rotation about the second lens guide bar 13a is prevented. In the following description, the second lens 2 and the second lens frame 8 are collectively referred to as a second lens unit 80.

  The third lens 3 is a lens that moves in the optical axis direction Z to perform focus adjustment, and is held by the third lens frame 9. The third lens frame 9 is movably engaged with the third lens guide bar 14a in the optical axis direction Z to be guided in the optical axis direction Z, and is also moved in the optical axis direction Z by the third lens rotation stopper bar 14b. As a result, the rotation around the third lens guide bar 14a is prevented.

  Like the second lens 2, the fourth lens 4 is a lens that moves in the optical axis direction Z to change the magnification, and is held by the fourth lens frame 10. The fourth lens frame 10 is movably engaged with the fourth lens guide bar 15a in the optical axis direction Z to be guided in the optical axis direction Z, and is also moved in the optical axis direction Z by the fourth lens rotation stopper bar 15b. As a result, rotation about the fourth lens guide bar 15a is prevented. In the following description, the fourth lens 4 and the fourth lens frame 10 are collectively referred to as a fourth lens unit 90.

  The imaging optical system further includes an aperture unit 6. The aperture unit 6 adjusts the amount of light passing through the imaging optical system by changing the aperture diameter. The aperture unit 6 is held by the second lens frame 8 and moves in the optical axis direction Z integrally with the second lens frame 8 during zooming.

  The imaging element 5 has a rectangular imaging surface having a long side and a short side. As shown in FIGS. 1, 7 and 8, the orientation of the imaging device (lens barrel 100) is such that the short side of the imaging element (imaging surface) 5 extends in the vertical direction Y and the long side extends in the horizontal direction X That. The vertical direction (second direction) Y and the horizontal direction X are directions orthogonal to the optical axis direction Z, respectively.

  2, 7, and 8 show the lens driving mechanism of the lens barrel 100 in the normal posture. Here, the configuration of the lens driving mechanism in the normal posture will be described. The object side and the image side in the optical axis direction Z are referred to as a front side and a rear side, respectively.

  The lens driving mechanism includes a cam plate 20 as a cam member, a cam plate guide bar 21 as a guide member, a cam plate rotation stop bar 22, a driving unit 16, and a torsion spring 19 as an urging member.

  The cam plate 20 has a cam groove (cam portion) to be described later that moves the second and fourth lens units 80 and 90 in the optical axis direction Z by moving in the vertical direction Y. A guided engagement portion (sleeve portion) 203 provided at the rear end of the cam plate 20 is engaged with the cam plate guide bar 21 so as to be movable in the vertical direction Y, whereby the cam plate 20 moves in the vertical direction Y. Guided. Further, the rotation stop engaging portion 204 provided at the front end of the cam plate 20 is engaged with the cam plate rotation stop bar 22 so as to be movable in the up-down direction Y, thereby connecting the cam plate guide bar 21 of the cam plate 20. Rotation about the center is prevented.

  The driving unit 16 includes an actuator that generates a driving force for moving the cam plate 20 in the vertical direction Y, and a driving circuit thereof. In this embodiment, a linear actuator is used as the actuator. Specifically, the vibration type linear actuator is constituted by a moving member 16a including a vibrator vibrated by a piezoelectric element and a stator member 16b extending in the vertical direction Y and contacting the moving member 16a. However, the cam plate 20 may be driven in the vertical direction Y using an actuator other than a linear actuator such as a rotating motor. The drive unit 16 is disposed between the guided engagement portion 203 of the cam plate 20 and the rotation stop engagement portion 204 in the optical axis direction Z.

  The drive section 16 has a rack member 17 and a rack spring 18 as its output section. The rack member 17 is engaged with a rack engaging portion 205 provided on the cam plate 20 by the urging force of the rack spring 18. The cam plate 20 is driven in the vertical direction Y by the driving force of the linear actuator transmitted through the rack member 17.

  The cam plate 20 is provided with a second lens cam groove 20a and a fourth lens cam groove 20b as the cam grooves described above. A second lens cam follower 8a provided on the second lens frame 8 is engaged with the second lens cam groove 20a, and a fourth lens cam follower 10a provided on the fourth lens frame 10 is engaged with the fourth lens cam groove 20b. are doing. When the cam plate 20 moves in the vertical direction Y, the second lens frame 8 (the second lens unit 80) and the fourth lens frame 10 (the fourth lens unit 90) are lifted by the second lens cam groove 20a and the fourth lens cam groove 20b. Is moved in the optical axis direction Z.

  The second lens cam groove 20a moves the second lens unit 80 forward when the cam plate 20 moves downward, and moves the second lens unit 80 rearward when the cam plate 20 moves upward. It has a shape to make it. The second lens cam groove 20a has a linear shape in which the inclination direction with respect to the optical axis direction Z is constant and the inclination angle with respect to the optical axis direction Z is constant.

  On the other hand, the fourth lens cam groove portion 20b changes the moving direction of the fourth lens unit 80 when the cam plate 20 moves in the upward direction and the downward direction (moves the lens unit 80 once to the rear side and then to the front side). ) Shape.

  Here, the force (moment) acting on the cam plate 20 in the normal posture will be described. As can be seen from FIG. 1, of the second and fourth lenses 2 and 4 moved by the cam plate 20, the mass of the second lens 2 is larger than the mass of the fourth lens 100. In the cam plate 20, the position where the second lens cam follower 8a engages with the second lens cam groove 20a and the guided engagement portion (guided portion) 203 which engages with the cam plate guide bar 21 are in the optical axis direction. Z are located on opposite sides of the drive unit 16.

  At this time, as shown in FIG. 2, a moment Ma generated by a force applied from the rack member 17 of the drive unit 16 to the rack engaging portion 205 acts on the cam plate 20 with the guided engaging portion 203 as a fulcrum. Further, a moment M2 generated by a force applied to the second lens cam groove 20a from the second lens unit 80 via the second lens cam follower 8a acts on the cam plate 20 with the guided engagement portion 203 also as a fulcrum.

  When the driving unit 16 drives the cam plate 20 in the downward direction, the own weight of the second lens unit 80 does not become a load on the driving unit 16 because the directions of the moment Ma and the moment M2 match each other. However, when the drive unit 16 drives the cam plate 20 in the upward direction, the directions of the moments Ma and M2 are opposite to each other, and the weight of the second lens unit 80 becomes a load on the drive unit 16. In particular, when the second lens unit 80 is located in the optical axis direction Z at a position (front side) apart from the drive unit 16 and the guided engagement part 203 of the cam plate 20, compared to a case where the second lens unit 80 is at a close position (rear side). The value of the moment M2 increases, and the load on the drive unit 16 increases. In the present embodiment, the urging force generated by the torsion spring 19 is used to reduce the load on the drive unit 16.

  The torsion spring 19 is held by a coil holding portion 19c by a spring holding portion 23 as a fixing member. The spring holder 23 will be described later. The first arm portion 19a of the torsion spring 19 extending from the coil portion 19c abuts a first spring receiving portion 201 provided on the cam plate 20, and applies an urging force Fs1 to the cam plate 20. The urging force Fs1 always urges the cam plate 20 guided in the vertical direction Y by the cam plate guide bar 21 in the normal posture (regardless of the position of the cam plate 20 in the vertical direction Y). The first spring receiving portion 201 is provided on the opposite side of the driving portion 16 from the cam plate guide bar 21 in the optical axis direction Z.

  The second arm portion 19b extending from the coil portion 19c abuts on a second spring receiving portion 202 provided on the cam plate 20, and applies an urging force Fs2 to the cam plate 20. The urging force Fs2 always urges the cam plate 20 backward (regardless of the position of the cam plate 20 in the vertical direction Y) in the normal posture. The second spring receiving portion 202 is provided at a position where the second arm portion 19b extending downward from the coil portion 19c held by the spring holding portion 23 abuts.

  The resultant force of the urging forces Fs1 and Fs2 exerts a moment Ms on the cam plate 20. The moment Ms is a moment opposite to the moment M2 and acts so as to cancel the moment M2, so that the load on the drive unit 16 due to the moment M2 is reduced. The angle formed between the first arm 19a and the second arm 19b of the torsion spring 19 (hereinafter, referred to as a spring angle) is θ.

  Next, a change in the force (moment) applied to the cam plate 20 when the cam plate 20 moves in the vertical direction Y, that is, when the second lens unit 80 moves in the optical axis direction Z will be described. When the second lens unit 80 is located at the rear end of the movable range in the optical axis direction Z, the imaging optical system is in a WIDE (wide angle) end state, and when the second lens unit 80 is located at the front end of the movable range, the imaging optical system is TELE ( (Telephoto) end state.

  FIG. 3 shows the lens driving mechanism in the WIDE end state. The moment Ms in the WIDE end state is represented by Msw, and the moment M2 is represented by M2w. The spring angle θ of the torsion spring 19 in the WIDE end state is represented by θw. FIG. 4 shows the lens driving mechanism in the telephoto end state. The moment Ms in the TELE end state is represented by Mst, and the moment M2 is represented by M2t. The spring angle θ of the torsion spring 19 in the TELE end state is represented by θt.

  In zooming from the WIDE end state to the TELE end state, the second lens unit 80 moves in a direction (forward) away from the guided engagement portion 203 of the cam plate 20 which is a fulcrum of each moment, so that the moment M2 The value increases. Therefore, M2w <M2t holds.

  At this time, the cam plate 20 moves downward from the upper end position to the lower end position. Accordingly, the position of the first spring receiving portion 201 of the cam plate 20 also moves downward, so that the first arm portion 19a is pushed in a direction in which the spring angle θ decreases. Similarly, the position of the second spring receiving portion 202 of the cam plate 20 also moves downward, but the position of the second arm portion 19b originally extending downward hardly changes. Therefore, the spring angle θ decreases toward the TELE end state, and θw> θt holds. Since the biasing force generated by the torsion spring 19 changes depending on the spring angle θ, the value of the moment Ms increases as the TELE end state is approached (as the second lens unit 80 moves further forward from the drive unit 16), and Msw <Msw < Mst holds.

  With such a configuration, the resultant force of the moment M2 and the moment Ms does not greatly change according to the zooming state (zoom position) from the WIDE end state to the TELE end state. It is possible to suppress (reduce the load).

  Next, the influence of the tilt posture of the imaging device (the lens barrel 100) on the above-described moment will be described. As shown in FIG. 7, the lens barrel 100 can be tilted (rotated) in the vertical direction Y about the tilt shaft serving as the spring holder 23 described above. FIG. 5 shows a lens driving mechanism in the lens barrel 100 in a depression angle posture (a posture looking down from above), which is one of the tilt postures of the lens barrel 100.

  When the attitude of the lens barrel 100 changes from the normal attitude to the depression angle attitude, the value of the moment M2 changes from the value at the time of the normal attitude, and the value after the change is the inclination angle of the second lens cam groove 20a with respect to the optical axis direction Z. It is determined by the tilt angle (depression angle) of the lens barrel 100. Assuming that the mass of the second lens unit 80 is m and the gravitational acceleration is g, the distance in the optical axis direction Z between the guided engagement portion 203 of the cam plate 20 and the second lens cam follower 8a of the second lens unit 80. Is L. The angle of inclination of the second lens cam groove 20a of the cam plate 20 with respect to the optical axis direction Z is α, and the tilt angle of the lens barrel 100 is β. At this time, the moment M2 is represented by the following equation (1).

M2 = m · g · L · cos α / cos (α−β) (1)
The moment M2 in the depression angle posture shown in FIG. 5 is represented as M2m. FIG. 6 shows the lens driving mechanism when the lens barrel 100 is in a downward posture, which is one of the tilt postures. The value of the moment M2 in this downward posture is represented as M2b.

  As a comparative example, as shown in FIG. 9A, the inclination direction of the second lens cam groove 20a 'is opposite to that of this embodiment (when the cam plate 20' moves downward in the normal posture, the second lens cam groove 20a 'moves downward). When the unit 80 moves rearward), an inflection point occurs in which the direction of the moment M2 changes while the lens barrel changes from the normal posture to the downward posture.

  FIG. 9A shows the moment acting on the lens driving mechanism when the lens barrel of the comparative example is in the normal posture. The moment Msm corresponds to the moment Ms in the embodiment. The moment M2a is a moment M2 generated by a force applied to the second lens cam groove 20a 'from the second lens unit 80 via the second lens cam follower 8a in the normal posture.

  FIG. 9B shows a moment Msm acting on the lens driving mechanism when the lens barrel is in the depression angle posture. At this time, since the second lens cam groove 20a 'extends substantially in the vertical direction, the moment M2 hardly occurs.

  FIG. 9C shows the moment Msm and the moment M2c acting on the lens driving mechanism when the lens barrel is in the downward posture. The moment M2c is the moment M2 in the downward posture, and is opposite in direction to the moment M2a. That is, the direction of the moment M2 changes between the normal posture side and the downward posture side with the depression angle posture as an inflection point.

  In this case, as shown in FIG. 9C, when the lens barrel is tilted so that the angle of depression is further increased than the inflection point, the directions of the moments Ms (Msm) and M2 (M2c) match, so that the lens mirror The load on the drive unit 16 when the magnification of the cylinder is changed from the TELE end state to the WIDE end state is increased.

  On the other hand, if the inclination direction of the second lens cam groove 20a is set so that the second lens unit 80 moves forward when the cam plate 20 moves downward in the normal posture as in the present embodiment. , The inflection point does not occur. Therefore, the moment M2m and the moment M2b have different absolute values, but have the same directions. Therefore, the load on the drive unit 16 can be reduced by the urging force of the torsion spring 19 regardless of the tilt posture of the lens barrel 100.

  The moment generated by the fourth lens unit 100 will be described. Since the fourth lens cam follower 10a where the fourth lens unit 100 and the cam plate 20 are engaged is located at a position close to the guided engagement portion 203 serving as the fulcrum of the moment, the moment is also reduced. For this reason, the moment generated by the fourth lens unit 100 hardly affects the load on the drive unit 16.

  As described above, according to the present embodiment, the driving unit 16 of the lens barrel 100 using the cam plate 20 that moves in the direction (Y) orthogonal to the moving direction (Z) of the second lens unit 80. The load can be reduced. As a result, downsizing of the lens barrel 100 (imaging device) can be realized.

  The second lens cam groove 20a does not necessarily have to have a linear shape as in the above embodiment, but has a non-linear shape in which the inclination angle with respect to the optical axis direction Z changes between the TELE end state and the WIDE end state. You may.

  Further, the configuration of the imaging optical system is not limited to that described in the above embodiment, and the lens moved by the cam plate is not for zooming, but may be for focus adjustment.

  Each of the embodiments described above is merely a representative example, and various modifications and changes can be made to each embodiment in practicing the present invention.

2 Second lens 16 Drive unit 19 Torsion spring 20 Cam plate 21 Cam plate guide bar

Claims (9)

An optical element movable in a first direction;
A cam member that moves the optical element in the first direction by moving in a second direction orthogonal to the first direction;
A guide member for guiding the cam member in the second direction;
A drive unit for moving the cam member in the second direction;
An urging member for urging the cam member,
The optical device, wherein the urging member is provided so as to urge the cam member upward in a state where the second direction is a vertical direction.   The urging member is provided such that the urging force acting on the cam member from the urging member increases as the optical element moves in a direction away from the driving unit in the first direction. The optical device according to claim 1, wherein: In a state where the second direction is the vertical direction,
The first direction includes an object side and an image side,
The optical element moves to the object side by the cam member moving downward,
The optical device according to claim 1, wherein the optical element moves to the image side when the cam member moves upward.   The optical device according to any one of claims 1 to 3, wherein the optical element has a larger mass than other optical elements moved by the cam member. The urging member is a torsion spring having a coil portion held by a spring holding portion, a first arm portion and a second arm portion extending from the coil portion,
The first arm portion contacts a first spring receiving portion provided on the cam member,
The optical device according to claim 1, wherein the second arm portion contacts a second spring receiving portion provided on the cam member.   In the cam member, the first spring receiving portion is provided on a side opposite to the guided portion guided by the guide member with respect to the driving portion in the first direction. The optical device according to claim 5, wherein   The optical device according to claim 5, wherein the spring holding portion is a shaft portion serving as a center of the tilt of the optical device in the vertical direction. An optical device according to claim 1,
An image pickup device for picking up an object image formed by light passing through the optical element. The imaging device has an imaging surface having a long side and a short side,
The imaging device according to claim 8, wherein the second direction is oriented in the up-down direction when the short side is oriented in the up-down direction.