JP2022047806A - Lens device and imaging apparatus - Google Patents

Abstract

To provide a lens device which is advantageous, for example, for at least one of the downsizing and the low power consumption of a motor.SOLUTION: The lens device comprises: a first lens barrel; a second lens barrel holding an optical member inside the first lens barrel; an operation ring rotatably held by the first lens barrel outside the first lens barrel; a conversion mechanism converting the rotation of the operation ring to the movement of the second lens barrel in the direction of an optical axis; an elastic member disposed inside the operation ring; and a pressurizing-object member which is pressurized against the outer surface of the first lens barrel by the elastic member.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lens device and an image pickup device having the same.

There is known a lens device in which a driving device for driving an optical system (lens group) in the lens barrel is attached to the outside of the lens barrel. In such a lens device, since there is a backlash between the operating member and the gear in the drive device, the position deviation (deviation with respect to the target position) of the optical system due to the backlash can be excessive. Patent Document 1 discloses a lens device in which a urging member for applying an urging force to a cam ring in a specific rotation direction of the cam ring is provided to reduce backlash in a gear portion regardless of the rotation direction of the cam ring.

Japanese Unexamined Patent Publication No. 2019-49655

In the lens device disclosed in Patent Document 1, since the urging force acts on the cam ring, the operating torque becomes large. Further, since the operating torque changes depending on the length of the spring as the urging member, it may be disadvantageous in terms of the size of the motor and the power consumption.

It is an object of the present invention to provide a lens device that is advantageous in at least one of the small size and low power consumption of a motor, for example.

In order to achieve the above object, the lens apparatus of the present invention includes a first lens barrel, a second lens barrel that holds an optical member inside the first lens barrel, and the first lens barrel outside the first lens barrel. An operating ring rotatably held by one lens barrel, a conversion mechanism that converts the rotation of the operating ring into movement of the second lens barrel in the direction of the optical axis, and an elastic member arranged inside the operating ring. It is characterized by having a pressed member that is pressed against the outer surface of the first lens barrel by the elastic member.

According to the present invention, for example, it is possible to provide a lens device which is advantageous in at least one of the small size and low power consumption of a motor.

It is sectional drawing of the variable magnification adjustment part in the lens apparatus of Example 1. FIG. FIG. 3 is a vertical sectional view of a main part of the lens device of the first embodiment. It is a detailed view of the elastic member of Example 1. FIG. It is a vertical sectional view of the main part of the lens apparatus of Example 2. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the illustrated examples in FIGS. 1 to 4. The description will be centered on the parts related to the present invention, and the parts not directly related to the invention are omitted.

FIG. 1 is a side sectional view of a magnification adjusting unit in a first embodiment of a lens device to which the present invention is applied. The left side of the figure is the subject side, and the right side is connected to an image pickup device (not shown).

A zoom operation ring 5 is arranged on the outer periphery of the fixed cylinder (first lens barrel) 1 of the lens device, and is rotatable with respect to the fixed cylinder 1. On the inner diameter side of the fixed cylinder 1, there is a cam cylinder 3 that rotates around the optical axis integrally with the zoom operation ring 5. A straight groove cylinder 2 fixed to the fixed cylinder 1 is provided on the inner diameter side of the cam cylinder 3. Here, the fixed cylinder 1 may have a configuration that directly holds the optical member, or may have a configuration that does not directly hold the optical member.

Gear teeth for engaging with the drive device 7 are arranged on a part of the outer peripheral surface of the zoom operation ring 5. Further, an index of the subject distance is engraved on a part of the outer peripheral surface of the zoom operation ring 5 (not shown).

Inside the lens device, a moving optical system 4 in which an optical element 41 for adjusting the magnification is held in a moving lens barrel (second lens barrel) 42 is arranged. On the outer peripheral portion of the moving lens barrel 42, three cam pins 43 extending in a direction orthogonal to the optical axis are fixed at a plurality of three locations at equal intervals of 120 ° around the optical axis. The three cam pins 43 are smoothly engaged with both the three pairs of straight grooves 2a provided in the straight groove cylinder 2 extending in the optical axis direction and the cam grooves 3a provided in the inner peripheral portion of the cam cylinder 3, respectively. It is slidable. With the above configuration, the cam pin 43 engages with the straight groove 2a provided in the fixed cylinder 1, thereby restricting the rotation of the moving lens barrel 42 around the optical axis. Therefore, when the photographer holds the zoom operation ring 5 and rotates the zoom operation ring 5 around the optical axis, the cam cylinder 3 rotates integrally with the zoom operation ring 5. As a result, the moving lens barrel 42 moves in the optical axis direction by the engagement between the cam groove 3a provided in the cam cylinder 3 and the cam pin 43 as a guide, and the scaling can be adjusted. That is, the cam cylinder 3 is configured on the inner diameter side of the fixed cylinder 1, has a cam groove 3a, and rotates around the optical axis integrally with the zoom operation ring 5, and is configured on the inner diameter side of the cam cylinder 3 and is configured on the optical axis. It has a straight groove 2a extending in the direction of The cam pin (shaft portion) 43 constitutes a conversion mechanism that converts the rotation of the zoom operation ring 5 into driving in the direction of the optical axis of the moving lens barrel 42.

As shown in FIG. 2, a drive device 7 is fixed to the fixed cylinder 1 on the outer peripheral portion of the lens barrel. A zoom gear 71 connected to a zoom motor (drive unit) 72 inside the drive device 7 projects from the drive device 7 toward the lens barrel. By attaching the drive device 7 to the lens barrel, the gears of the zoom operation ring 5 and the zoom gear 71 are engaged with each other, and the zoom operation ring 5 can be electrically driven.

Although not shown here, each operation ring of the focus and the iris can be electrically driven by connecting the gears in the same manner as the zoom.

A position detection mechanism 73 is configured in the drive device 7, and the rotation angle of the zoom operation ring 5 can be detected by engaging the gear teeth of the zoom operation ring 5 and the position detection mechanism 73 with each other. It will be possible. The backlash of the zoom operation ring 5 and the zoom gear 71 is determined by fixing the drive device 7 to the fixed cylinder 1.

On the other hand, inside the zoom operation ring 5, a brake mechanism 6 for suppressing the backlash of the optical system due to the backlash of the zoom operation ring 5 and the zoom gear 71 is provided. FIG. 3 shows a vertical cross-sectional view of the brake mechanism 6 with respect to the fixed cylinder 1.

An elastic member 61 is fixed to the inner diameter side of the zoom operation ring 5 with a screw, and a sliding member (pressed member) 62 is attached to the inside in the radial direction on the other end side of the elastic member 61. The sliding member 62 is always urged by the elastic member 61 to the outer surface of the fixed cylinder 1 on the inner diameter side of the zoom operating ring 5. Here, a member having a high coefficient of friction may be attached to the sliding surface of the sliding member 62 with the fixed cylinder 1. In this embodiment, an example in which a leaf spring is used as the elastic member 61 is shown, but the present invention is not limited thereto. As the elastic member 61, one end may be fixed to the zoom operation ring 5, and the other end may be an elastic member that presses the sliding member 62 against the outer peripheral surface of the fixed cylinder 1, and may be composed of a coil spring, an air spring, or the like. ..

Further, a gap is formed between the inner diameter of the zoom operation ring 5 and the elastic member 61 so that the elastic member 61 does not interfere with the zoom operation ring 5 even when the elastic member 61 is deformed.

The gear play suppressing mechanism action of the mobile optical system 4 in this embodiment configured as described above will be described below.

First, consider a case where the brake mechanism 6 of the zoom operation ring 5 is located on the lower side in the vertical direction of the lens barrel in a posture in which the optical axis is horizontal. At this time, the force that tries to move by its own weight does not act on the moving optical system 4 in either the moving direction of the subject side or the image side.

Further, the sliding member 62 is pressed against the fixed cylinder 1 by the elastic member 61 fixed inside the zoom operation ring 5, and a urging force is always applied. However, since the force of the own weight of the sliding member 62 of the brake mechanism 6 acts in the direction opposite to the direction of the urging force of the elastic member 61, the force applied to the fixed cylinder 1 slides from the urging force of the elastic member 61. The force is obtained by subtracting the own weight of the member 62. Further, since the zoom operation ring 5 is rotated by the scaling adjustment, the brake mechanism 6 is also rotated accordingly. Therefore, the direction of the own weight acting on the brake mechanism 6 changes depending on the rotation position, and the spring force of the elastic member 61 is increased. Depending on the balance, the urging force against the fixed cylinder 1 also changes. However, in a state where the zoom operation ring 5 is not rotating no matter where the rotation position of the zoom operation ring 5 is, the elastic member 61 and the sliding member are always exerted by the elastic member 61 against the fixed cylinder 1. 62 is configured.
Next, the operation of the gear backlash suppressing mechanism when the variable magnification adjustment is performed by the drive device 7 will be described.

First, when the gears of the zoom operation ring 5 and the zoom gear 71 are not in contact with each other due to backlash and there is a gap between the gear teeth, when the movement starts, until the gear teeth of the zoom gear 71 come into contact with the gear teeth of the zoom operation ring 5. , The zoom gear 71 rotates (idles). Since the speed is low when the vehicle starts to move, the centrifugal force applied to the sliding member 62 of the brake mechanism 6 in the radial direction is small. Therefore, the fraudulent force for pressing the outer peripheral surface of the fixed cylinder 1 from the zoom operation ring 5 is not significantly reduced. In the low-speed drive region, the motor can generate a large torque, and stable rotational drive (starting) becomes possible. When the rotation drive is continued, the gear teeth of the zoom operation ring 5 and the zoom gear 71 come into contact with each other, and the position detection mechanism 73 engaged with the zoom operation ring 5 starts to rotate and the position starts to be detected. 4 can control the movement to a desired target position.

Further, considering the case where the scaling adjustment is performed significantly, the amount of movement of the moving optical system 4 becomes large, and the operating rotation angle of the zoom operating ring 5 also becomes large. Since it is desired to adjust the magnification in a short time at the time of shooting, it is necessary to move the moving optical system at high speed at the time of large magnification adjustment, and it is necessary to rotate the zoom operation ring 5 at high speed. Therefore, when the zoom operation ring 5 that has been driven at a low speed and started to move gradually increases the rotation speed, the centrifugal force in the radial direction increases due to the effect of the sliding member 62 configured in the brake mechanism 6. When this happens, the urging force of the elastic member 61 applied to the fixed cylinder 1 from the zoom operating ring 5 is gradually canceled, the pressing force of the sliding member 62 on the fixed cylinder 1 is reduced, and the rotational torque of the zoom operating ring 5 is increased. It gets smaller. As a result, it is not necessary to use a motor having higher torque characteristics in the high speed region while applying a braking force to the rotation of the zoom operation ring 5 in the low speed region, and the motor does not need to be increased in size. It is possible to realize the desired rotation drive control of the zoom operation ring 5. Depending on the weight of the sliding member 62, the centrifugal force acting in the direction away from the outer peripheral surface of the fixed cylinder 1 that acts against the elastic force of the elastic member 61 during the rotation of the zoom operating ring 5 changes. Therefore, the diameter of the zoom operation ring 5, the operation range / operation speed of the zoom operation ring 5, the elastic modulus of the elastic member 61, the weight of the moving member such as the moving lens barrel 42 by the operation of the zoom operation ring 5, and the profile of the curved cam. It is preferable that the weight of the sliding member 62 is set based on the above.

Up to this point, the explanation has been made on the assumption that the lens barrel is in a horizontal state, but the gear play suppressing mechanism action when the lens barrel is greatly tilted will be described.
When the subject side of the lens barrel is tilted downward, a force that tends to move toward the subject side acts on the moving optical system 4 due to its own weight. Here, the magnitude of the force that the moving optical system 4 tries to move by its own weight is substantially proportional to the sine and cosine of the tilt angle of the optical axis of the lens barrel with respect to the horizontal direction. That is, a force that tries to rotate arbitrarily with a torque substantially proportional to the sine and cosine of the tilt angle of the optical axis of the lens device acts on the zoom operation ring 5 due to its own weight.

Consider the urging force of the brake mechanism 6 at this time. In the elastic member 61, when the optical axis is horizontal, the sliding member (pressed member) 62 is placed on the outer surface of the fixed cylinder 1 in the direction opposite to the direction of gravity acting on the elastic member 61. Pressing. When the brake mechanism 6 is located on the lower side in the vertical direction of the lens barrel, the weight applied to the brake mechanism 6 is the direction of the force that the elastic member 61 urges the fixed cylinder 1 by the angle at which the lens device is tilted. It shifts. Therefore, the self-weight component in the direction of canceling the urging force of the elastic member 61 is a sine of the tilt angle of the optical axis of the lens barrel with respect to the horizontal direction, and becomes smaller as the tilt angle of the lens barrel is larger. On the other hand, when the brake mechanism 6 is located on the upper side in the vertical direction of the lens barrel, the self-weight component in the direction of increasing the urging force of the elastic member 61 increases as the tilt angle of the lens barrel increases (in the optical axis direction and in the horizontal plane). The larger the angle, the smaller the angle. That is, the more the subject side of the lens barrel is tilted downward, the smaller the influence of the rotational position of the zoom operation ring 5 on the urging force of the elastic member 61. Therefore, when the brake mechanism 6 is located on the lower side in the vertical direction of the lens barrel, the more the subject side of the lens device is tilted downward, the more the urging force that presses the sliding member 62 acting on the fixed cylinder 1 is. To increase. Therefore, by configuring the gear play suppressing mechanism, it is possible to prevent the moving optical system 4 from moving due to its own weight in the tilted posture of the lens device.

FIG. 4 is a vertical cross-sectional view of a main part of the scaling adjustment unit in the second embodiment of the lens device to which the present invention is applied. The same reference numerals as those in the first embodiment indicate the same members. Hereinafter, the points where the configuration is different from that of the first embodiment will be described.

In this implementation system, the brake mechanism 6 for suppressing the backlash of the optical system due to the backlash of the zoom operation ring 8 and the zoom gear 71 is equally separated from each other in the circumferential direction about the center of the optical axis inside the zoom operation ring 8. It is arranged at a plurality of three places. As a result, the center of gravity of the zoom operation ring 8 and the center of rotation are substantially aligned with each other, and it is possible to reduce the rotational torque unevenness when the zoom operation ring 8 is rotated. Further, the amount of change in the braking force with respect to the rotation of the zoom operation ring 8 due to the pressing of the sliding member 62 acting on the fixed cylinder 1 due to the rotation position of the zoom operation ring 8 becomes small. In this embodiment, the number of brake mechanisms 6 is three, but the number of brake mechanisms 6 does not matter as long as the center of gravity of the zoom operation ring 8 and the center of rotation are substantially the same. Other than this, since it is the same as that of the first embodiment, the description thereof will be omitted.

In the embodiment, the configuration relating to the zoom operation for operating the drive of the zoom optical system has been described, but the present invention is not limited thereto. The same can be applied to a configuration related to a focus optical system for operating the drive of the focus optical system and a configuration for operating the drive of the aperture stop, and the same effect can be enjoyed.

By configuring an image pickup device having the illustrated lens device and an image pickup device that captures an image formed by the lens device, it is possible to provide an image pickup device that can enjoy the effects of the present invention. Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and modifications can be made within the scope of the gist thereof.

1: Fixed cylinder (first lens barrel)
2: Straight groove cylinder (conversion mechanism)
2a: Straight groove (conversion mechanism)
3: Cam cylinder (conversion mechanism)
3a: Cam groove (conversion mechanism)
4: Mobile optical system (optical member)
5,8: Zoom operation ring 6: Brake mechanism 41: Optical element (optical member)
42: Moving lens barrel (second lens barrel)
61: Elastic member 62: Sliding member (pressed member)

Claims (11)

With the first lens barrel,
A second lens barrel that holds the optical member inside the first lens barrel, and
An operation ring rotatably held by the first lens barrel on the outside of the first lens barrel,
A conversion mechanism that converts the rotation of the operating ring into the movement of the second lens barrel in the direction of the optical axis.
An elastic member arranged inside the operating ring and
A lens device having a pressed member pressed against the outer surface of the first lens barrel by the elastic member. The lens device according to claim 1, wherein the conversion mechanism is arranged inside the first lens barrel and has a cam cylinder that rotates around the optical axis together with the operation ring. The lens device according to claim 1 or 2, wherein the elastic member presses the pressed member against the outer surface in a direction orthogonal to the optical axis. The claim is characterized in that the elastic member presses the pressed member against the outer surface in a direction opposite to the direction of gravity acting on the elastic member in a state where the optical axis is horizontal. The lens device according to any one of items 1 to 3. The lens device according to any one of claims 1 to 4, wherein the elastic member and the pressed member are arranged at a plurality of separated locations around the optical axis. The lens device according to any one of claims 1 to 5, wherein the elastic member includes at least one of a leaf spring, a coil spring, and an air spring. The lens device according to any one of claims 1 to 6, wherein the force of the pressed member pressing the outer surface decreases as the rotation speed of the operating ring increases. The lens device according to any one of claims 1 to 7, wherein the lens device has a drive unit that engages with the operation ring to rotationally drive the operation ring. The lens device according to any one of claims 1 to 8, wherein the optical member includes at least one of a lens and an aperture diaphragm. The lens device according to any one of claims 1 to 9, wherein the elastic member is fixed to the operation ring. An image pickup apparatus comprising the lens apparatus according to any one of claims 1 to 10 and an image pickup element for taking an image formed by the lens apparatus.

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