JPH0331929Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of the Invention) The present invention relates to a lens barrel, and in particular an ultrasonic motor that obtains a rotational action by utilizing the electrostrictive action of a piezoelectric element and controls the movement of a lens using this rotational action. This invention relates to a lens barrel incorporating a vibration motor such as the above.

(Prior Art) Conventionally, a motor is built into a lens barrel for focusing and variable magnification of a focus lens or zoom lens, and the motor is driven by an electric signal from a focus detection means or a zoom control means. Many lens barrels are known. Conventional motors installed in lens barrels are motors with coils wound around an iron core, called iron core motors, coreless motors, and brushless motors.
A so-called solid type motor has a structure in which the rotating shaft is fixed to an iron core, or a structure in which the rotating shaft is fixed to a permanent magnet and a coreless coil is wound around the permanent magnet, or the present applicant's previous application ( Jitsugan No. 59-2198, 59-2199)
A hollow type motor is known in which a rotor portion and a stator portion of the motor have a hollow structure. Furthermore, stepping motors are also known as hollow motors.

(Problems to be Solved) The previously used solid type motors and hollow type motors have a structure that utilizes rotational motion based on electromagnetic action, and have various problems in the rotation of the rotor.

One of the problems is vibration when the rotor rotates.
In the case of lens barrels and lenses for single-lens reflex cameras, and lens barrels for shutter cameras, the vibrations cause camera shake and cause blurring of focus.

Further, the vibrations are accompanied by vibration sounds, and the vibration sounds give a feeling of discomfort to the photographer.

Furthermore, the electromagnetic motor described above requires a reduction gear train to control the rotational speed and rotational torque of the rotor for driving the lens, and in order to incorporate the reduction gear train into the lens barrel, the lens barrel structure becomes complicated and parts are required. This has led to an increase in the number of parts and the complexity of the assembly process, which has a significant impact on costs.

(Means for Solving the Problem) The present invention uses a vibration motor such as an ultrasonic motor as a drive source to move the movable lens in the optical axis direction, thereby solving the problems encountered when using a conventional type of motor. be.

In addition, the present invention appropriately deals with the spring biasing force of the spring member provided in the vibration motor,
Furthermore, it provides a compact lens barrel.

This invention consists of a cylindrical fixed tube, a movable lens,
a cylindrical moving ring that is disposed at an inner diameter position of the fixed barrel and moves the movable lens in the optical axis direction as the movable lens moves in the optical axis direction; and a cylindrical moving ring that is disposed between the fixed barrel and the movable ring. a bearing having a rotary ring installed at an outer diameter position of the movable ring that receives a bearing ball and rotates; a stator; It has a rotating body that rotates around the optical axis due to vibration,
a vibration motor disposed in a radial space formed by the bearing, the rotating body rotates a rotating ring that constitutes a part of the bearing, and the inner diameter surface of the rotating ring is rotated by the rotating body. and an outer diameter surface of the movable ring, the movable ring is moved in the optical axis direction by rotation of the rotary ring, and constitutes a part of the rotating body and the bearing. The rotating ring is in contact with the rotating ring in the optical axis direction, and the spring biasing force of the spring member in the vibration motor is received in the optical axis direction on one side in the optical axis direction by the fixed cylinder and on the other side in the optical axis direction. It features a lens barrel.

(Embodiment of the present invention) FIG. 1 shows a sectional view of an example of a lens barrel of the present invention. In the figure, reference numeral 1 denotes a fixed cylinder, and a bayonet ring 2 is fixed to the rear end with screws 4.

2a indicates a bayonet claw of the bayonet ring 2. Reference numeral 6 denotes a mount lid member, in which a cylindrical portion 6b is integrally molded from the inner diameter of the disk portion 6a by resin molding.

The mount lid member 6 is integrally formed with a plurality of engagement claws 6c that protrude rearward from the outer periphery of the disc portion 6a, and these engagement claws 6c are connected to the bayonet ring 2.
The elasticity of the resin is used to fit and fix it into the engagement groove or hole provided in the.

8 is a rotating ring with a helicoid 8 on the inner peripheral surface of the cylinder.
a, and a ring-shaped protrusion 8c on the outer periphery of which a ball race 8b on which the bearing ball 10 rotates is formed.

Ball holding rings 14 and 16 hold the balls 10 and form a bearing section together with the ring-shaped protrusion 8c of the rotary ring 8.

The ball retaining ring 14 has an engagement groove or hole on its outer circumference that engages with the protrusion 1a formed on the inner circumference of the fixed cylinder 1, and has an inclined surface for holding the ball 10 on its inner diameter surface.

The ball retaining ring 16 is provided with a threaded portion 16a on its outer periphery to be screwed into the threaded portion 1b formed on the inner periphery of the fixed cylinder 1, and an inclined surface for holding the ball 10.
Reference numeral 18 indicated by a two-dot chain line indicates the arrangement position of the movement amount detection device. An ultrasonic motor 20 for rotationally driving the rotating ring 8 is provided between the rotating ring 8 and the fixed cylinder 1.
Allocate.

The ultrasonic motor 20 consists of a rotor part and a stator part, and the stator part includes a vibrating body 20a, a piezoelectric element 20b fixed to the vibrating body 20a, a felt 20c, a felt holding member 20c ₁ , and a spring member 2.
0d, the rotor portion includes a friction member 20e, and a rotating body 20g that is a connecting member with the rotating ring 8.
The stator part consists of a fixed cylinder 1
The ball retaining ring 14 is fitted into the inner periphery of the rotor part with a clearance, and the rotor part and the rotating ring 8 are fitted into the ball retaining ring 14,
By screwing the ball retaining ring 16 into the threaded portion 1b of the fixed tube 1 via the ball 10, the ultrasonic motor 20 is held by the spring member 20d being pressed against the surface of the collar-like protrusion 1c of the fixed tube 1.

22 indicates a movable cylinder. As shown in FIG. 1, the movable cylinder 22 includes a cylinder part 22a, a helicoid part 22b screwed into the helicoid 8a of the rotating ring 8, and a lens L.
The lens holding frame portion 22c that holds the lens holding frame portion 22c, the wall portion 22d that connects the tube portion 22a and the lens holding frame portion 22c, and the tube portion 2
A key groove 22e provided in the cylindrical part extending toward the camera body 2a, and a cylindrical part extending from the cylindrical part 22a toward the subject, protruding in the radial direction with respect to the optical axis _O1 , and a mounting part for attaching accessories such as a filter. It has 22f. A lens holding ring 24 holds the lens groups L ₁ to _{L 3} and is fixed to the helicoid tube 22 .

26 is a known aperture unit, 26a is an aperture blade opening/closing ring, and rotor 28a of an electromagnetic motor 28.
are integrally combined with. 28b is the rotor 28a
The diaphragm unit and motor 28 are fixed to the helicoid tube 22 with screws 23 as a stay for driving the diaphragm unit and the motor 28.

Next, the operation of the lens barrel configured in FIG. 1 will be explained.

When the lens barrel shown in Figure 1 is attached to the camera,
The autofocus device on the camera side operates and drives the ultrasonic motor 20. The rotation of the rotating body 20g of the motor 20 causes the rotating ring 8 connected to the rotating body 20g to rotate around the optical axis. The rotary ring 8 is screwed into the cylinder 22, and the key member 30 fixed to the fixed cylinder 1 is engaged in the key groove 22e of the cylinder 22, so that the cylinder 22 is connected to the lens L ₁ -
Focus control is performed by holding L ₆ and moving in the direction parallel to the optical axis by rotating it by 20 g.

On the other hand, for exposure control, when the exposure control device on the camera side is activated and the stator 28b is energized,
As the rotor 28a rotates, the integrally connected aperture blade opening/closing ring also rotates, and the known aperture blades are controlled to an appropriate exposure aperture value.

(Effects of the present invention) By arranging the vibration motor in the radial space formed by the bearing, the present invention makes it possible to provide a lens barrel with a cylindrical outer shape without increasing the diameter. did it. Furthermore, by using a bearing to receive the spring biasing force of the spring member for press-contacting the stator and the rotating body in the vibration motor in the optical axis direction, a large load can be prevented from being generated. Furthermore, the rotation of the vibration motor is transmitted to a rotating ring that constitutes a part of the bearing, and the moving ring is moved in the optical axis direction by a helicoid mechanism between the inner diameter surface of this rotating ring and the outer diameter surface of the moving ring. Since the movable lens is moved, the number of parts can be reduced and a compact lens barrel can be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the lens barrel. Explanation of the symbols representing the main parts: 1 is a fixed cylinder;
8 is a rotating ring, 20 is an ultrasonic motor, 20a
is a vibrating body, 20b is a piezoelectric element, 20g is a rotating body,
22 is a helicoid tube, 26 is an aperture unit, 28
is an electromagnetic motor.

Claims (1)

[Claims for Utility Model Registration] A cylindrical fixed tube, a movable lens, and a cylinder that is disposed at an inner diameter position of the fixed tube and that moves the movable lens in the optical axis direction as it moves in the optical axis direction. a bearing disposed between the fixed cylinder and the movable ring and having a rotary ring at an outer diameter position of the movable ring that rotates while receiving a bearing ball; a stator; On the other hand, it has a rotating body that is spring-biased in the optical axis direction by a spring member and rotates around the optical axis due to vibration of the stator, and the rotating body is provided in a radial space formed by the bearing. a vibration motor arranged therein, wherein a rotating ring forming a part of the bearing is rotated by the rotating body, and a vibration motor is formed between an inner diameter surface of the rotating ring and an outer diameter surface of the movable ring. The movable ring is moved in the optical axis direction by the rotation of the rotating ring by the helicoid mechanism, and the rotating body and the rotating ring forming a part of the bearing are brought into contact in the optical axis direction, and the vibration motor A lens barrel characterized in that the spring biasing force of the spring member is received in the optical axis direction by the fixed barrel on one side in the optical axis direction and by the bearing on the other side.