JP2841679B2 - Lens moving device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lens moving device used for a video camera or the like.

2. Description of the Related Art In recent years, as a lens of a video camera, an inner focus method in which focusing is performed by a lens other than the front lens such as a master lens instead of a focusing method using a front lens has been proposed.

Hereinafter, an example of the above-described conventional lens moving device will be described with reference to the drawings.

FIG. 3 is a sectional view of a main part of a conventional lens moving device. In FIG. 3, the outer cylinder 1 is a master lens group 2
Is held with a ball bearing 4 interposed so as to be slidable in the optical axis direction 10. A motor 5 having a feed screw formed on a shaft 6 is fixed to a motor mount 8 fixed to the outer cylinder 1, and one end of the shaft 6 is held by a bearing mounted on the motor mount 8. The feed screw portion 6a of the shaft 6 includes:
The moving piece 7 having a screw is screwed together, and the driving piece 9 and the inner cylinder 3 are connected by the connecting arm 9. At this time,
The outer cylinder 1 is provided with an elongated hole 9a in the optical axis direction that enables the arm 9 to move in the optical axis direction.

With the above configuration, the moving piece 7, the arm 9, and the inner cylinder 3 linearly move in the optical axis direction by rotating the shaft 6 of the motor 5, and the master lens group 2 fixed to the inner cylinder 3 is focused. I have.

Problems to be Solved by the Invention However, in the above-described configuration, it is necessary to apply grease or the like to the screw in order to improve the slidability between the feed screw and the moving piece. If it is in contact, the load on the motor will increase due to the viscosity of grease, and a high-torque motor will be required to deteriorate the temperature characteristics at low temperatures. Power consumption, weight, There was a problem that both volumes increased. In addition, there is a clearance for sliding between the feed screw and the moving piece, and this clearance causes hysteresis in the moving distance of the master lens group with respect to the rotation of the motor shaft, resulting in unstable focusing operation. There was also the problem of becoming. Further, there is a problem that noise is generated.

In view of the above problems, the present invention reduces the load and prevents the occurrence of hysteresis by pressing a notched nut screwed into the feed screw of the motor shaft at 180 ° or less around the circumference of the feed screw to reduce the load, and An object of the present invention is to provide a quiet lens moving device without noise.

Means for Solving the Problems In order to solve the above problems, a lens frame holding the lens moving lens of the present invention and two guide poles holding the lens frame so as to be movable in the optical axis direction. A driving means integral with a motor shaft having a feed screw, a notch nut screwed into the feed screw of the drive shaft with a circumference of 180 ° or less; A second guide means comprising a single guide pole disposed on a motor mounting body that slides and holds rotatably in parallel to an axis, wherein the driving piece is A pressing means for pressing the drive shaft is provided between the drive piece and the lens frame, the drive piece and the lens frame are inserted and engaged without a gap in the optical axis direction, and the drive piece is rotated by the drive to rotate the drive piece. Driving in the optical axis direction This is a lens moving device that moves a lens by driving a lens frame.

Operation With the above-described configuration, the notched nut has a reduced contact area due to thread engagement with the feed screw, and can prevent an increase in load due to the viscosity of grease, so that a low-torque motor can be used, and low power consumption is achieved. Size and weight reduction can be achieved. In addition, the pressing means presses and urges the notch nut to the feed screw, thereby eliminating backlash due to screwing of the feed screw and the notch nut, reducing hysteresis of the moving distance, and achieving accurate focusing operation. It can be carried out. Further, by pressing the notch nut against the drive shaft, lateral pressure is applied to the drive shaft, so that clearance noise generated between the drive shaft and the bearing can be eliminated, and a quiet lens moving device can be realized.

Embodiment Hereinafter, a lens moving device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a main part showing a configuration of a lens moving device according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of a main part of FIG. 1 and 2, the master lenses 11 and 12 are held on a resin lens frame 13 by means such as caulking by heating.
Are slidably held in the optical axis direction 17 by first guide poles 15 and 16 disposed inside. Also, the lens frame
At the top of 13, a feed screw 21a formed on the shaft of the motor 20
Is provided with a groove 13a for inserting a drive piece 18 formed of a notch nut 18a screwed into the circumference of 120 °. The groove 13b has no gap in the optical axis direction when the driving piece 18 is inserted, and has a slight gap in the direction perpendicular to the optical axis.

The drive piece 18 having the notch nut 18a is held so that one end thereof is slidable and rotatable by a second guide pole 24 provided on the motor mount 23 in parallel with the drive shaft 21. And a coil spring 19 disposed between the lens frame 13 and
With the second guide pole 24 as a fulcrum, the drive shaft 21
The notch nut 18a and the feed screw 21a are screwed together without any gap. The drive shaft 2
The pressing force between 1 and the driving piece 18 is larger than the holding force between the lens piece 13 and the driving piece 18.

The operation of the lens moving device configured as described above will be described below.

A drive shaft 21 having a feed screw 21a when the motor 20 rotates
The driving piece 18 having the notch nut 18a screwed with a small clearance slides on the second guide pole 24 and moves in the optical axis direction, so that the lens frame engaged with the driving piece 18 The reference numeral 13 correctly obtains a predetermined moving distance with respect to the rotation angle of the motor 20, and performs the focusing operation of the master lenses 11, 12.
At this time, the notch nut 18a screwed to the feed screw 21a is
The contact portion with the feed screw 21a is only 120 ° with respect to the circumferential direction, thereby reducing the resistance loss due to the contact. Further, since the lateral pressure pressed by the drive piece 18 is applied to the drive shaft 21, noise due to the clearance between the drive shaft 21 and the bearing 22 can be suppressed.

As described above, according to this embodiment, the driving piece having the notch nut in which the lens frame is engaged with the driving shaft of the motor is pressed, the load for driving the lens is reduced by this driving piece, and the low torque motor is used. An object of the present invention is to provide a high-precision, low-noise lens moving device which can be used, prevents hysteresis, and prevents clearance noise.

Effect of the Invention As described above, the present invention provides a lens frame for holding a lens and a first frame for holding the lens frame movably in the optical axis direction.
A drive shaft of a motor having a feed screw portion, a drive piece having a notched nut screwed into the feed screw of the drive shaft, a second guide means for holding the drive piece, The contact area between the feed screw portion and the notched nut is reduced by providing a pressing means for pressing and pressing the notched nut to the drive shaft, and an increase in load due to the viscosity of grease can be prevented. It can be used, and low power consumption and small size and light weight can be achieved. In addition, since the nut is pressed against the feed screw portion, the hysteresis of the movement of the lens frame with respect to the rotation of the motor is reduced, and a side pressure is applied to the motor shaft by the notched nut pressing the drive shaft of the motor. Therefore, an excellent effect that a quiet and accurate focusing operation without clearance noise can be performed can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a principal part showing a configuration of a lens moving device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of main parts of FIG. 1, and FIG. 3 is a principal part of a conventional lens moving device. It is sectional drawing. 11,12 …… Master lens, 13 …… Lens frame, 15,16 ……
1st guide pole, 18 ... drive piece, 18a ... drive piece with a notched nut, 19 ... coil spring, 20 ... motor, 21 ... drive shaft, 21a ... feed screw, 24 ... second Guide pole.

Claims (1)

(57) [Claims] 1. A lens frame for holding a lens, a first guide means comprising two guide poles for holding the lens frame movably in an optical axis direction, and a motor shaft having a feed screw. Drive shaft and the circumference of the feed screw of this drive shaft
A drive piece having a notched nut screwed to 180 ° or less,
A second guide means comprising a single guide pole provided on a motor mount for holding the drive piece slidably and rotatably in parallel with the drive shaft. Pressing means for pressing the drive piece against the drive shaft is provided between the drive piece and the lens frame, and the drive piece and the lens frame are inserted and engaged without a gap in the optical axis direction; A lens moving device that drives the driving piece in the optical axis direction by rotating the lens, and moves the lens by driving the lens frame.