JPH0486713A - Driving device - Google Patents

Abstract

PURPOSE:To decrease the torque loss at the time of driving a movable member by axially providing plural pieces of coils which are successively switched in impressed voltage on the inner peripheral surface of a hollow cylindrical member and providing magnets in the movable member. CONSTITUTION:Magnetic materials 2, 2' are fixed t the inner peripheral surface of a lens barrel 1 and the coils 3, 3' are so wound thereon that the poles thereof vary respectively. Magnetic materials 20, 20' are similarly fixed thereto in the positions shifted axially from the magnetic materials 2, 2' and the coils 30, 30' are wound around these materials by reversing the winding direction. Plural pieces of the electromagnets consisting of these magnetic materials and the coils are disposed alternately in the axial direction and the movable member 4 is axialy driven on the inner side thereof. The movable member 4 consists of the cylindrical member 5 consisting of the magnetic material and a lens holding member 6 fixed in this member. The N poles and S poles are magnetized alternately around both ends of the cylindrical member 5 so as to vary in the optical axis direction. The movable member comes into contact with the driving part only at the two points and does not generate the surface contact and, therefore, there are no friction losses and the efficient driving is possible.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention comprises a hollow cylindrical member and a movable member disposed concentrically movably inside the cylindrical member. The present invention relates to a drive device configured to be driven in the axial direction, and particularly to a drive device suitable for use in optical devices that require operations such as autofocus and zooming.

[Conventional technology]

Devices for linearly driving a member in the axial direction are used in various fields, and even in optical devices, lens elements are appropriately driven in the optical axis direction.

That is, in conventional optical instruments having at least an optical system for focusing, D is used as a means for driving all or part of the optical system for autofocus and zooming.
A C motor, a step motor, a voice coil motor, etc. are employed, and the driving force of the motor is transmitted via a reduction gear or a timing belt, or directly by a transmission mechanism such as a feed screw mechanism. However, there are problems such as high noise and vibration, high loss torque and backlash, and difficulty in reducing size and weight. In order to solve these problems, JP-A No. 58-16208 provides a lens barrel mechanism equipped with an electric 6n rust guiding mechanism for moving an optical system holding member along the optical axis, and JP-A No. 62-162 No. 118748 provides a magnetic circuit configuration that improves the generated thrust for moving an optical system holding member along the optical axis by a linear motor.

As described above, lens barrel structures have been proposed that include various motors and drive mechanisms for directly moving the lens along the optical axis in the lens barrel.

(Problems to be Solved by the Invention) Conventional moving mechanisms, including the drive device for the optical system as described above, generally use a par-sleeve method or an inner diameter fitting method, so the contact area between the fixed part and the movable part is Because it is large,
The disadvantage is that a large amount of torque loss occurs due to friction in the contact area.

Therefore, an object of the present invention is to provide a drive device with small torque loss when a movable member is driven,
Furthermore, another object of the present invention is to provide a drive device that does not generate noise, vibration, etc., and can also be made smaller and lighter.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a hollow cylindrical member and a movable member that is movably disposed concentrically inside the cylindrical member, On the inner circumferential surface of the hollow cylindrical member, a driving section consisting of a plurality of coils whose applied voltage can be sequentially switched is fixed in a direction perpendicular to the central axis, and on the outer circumferential surface of the DFKI material, A magnet is provided corresponding to the driving member.

[Function] Since the present invention is configured as described above, voltages are sequentially applied to the coils. As a result, the polarity of the drive section also changes sequentially. Therefore, the magnets on the outer peripheral surface of the movable member are also sequentially attracted, and the movable member moves in the axial direction inside the cylindrical member.

In other words, the magnet of the movable member is attracted to and comes into contact with the drive part, but since the drive part is switched sequentially, the contact part also changes sequentially around the central axis, and the movable member is driven in the axial direction while making a spiral motion. Ru.

(Example) Hereinafter, an example will be described in which the hollow cylindrical member is used as a lens barrel of an optical system, and the movable member is used as a lens holding member.

Now, referring to FIG. 1.2, it will be easily understood that this is an example of an optical system in which a lens 7 is disposed inside the lens barrel 1 and the lens moves in the optical axis direction. Ru.

Magnetic materials 2.2° are fixed to the inner circumferential surface of the lens barrel 1, that is, in the X direction as shown in FIG. The coil 33 is wound in the opposite direction. Similarly, in the X direction, the magnetic material 20.20° is fixed by shifting the position in the axial direction from the magnetic material 2.2°, and the coil 30.30' is similarly wound with the winding direction reversed. has been done.

An electromagnet made of these magnetic materials and a coil is
As shown in FIG. 1, a plurality of movable members 4 are arranged alternately in the axial direction, and a movable member 4 is driven in the axial direction inside the movable members 4.

The movable member 4 consists of a hollow cylindrical member 5 made of a magnetic material such as a plastic magnet, and a lens holding member 6 fixed inside this member.
is held by this holding member. As shown in FIG. 3, both ends of the hollow cylindrical member 5 are magnetized with N poles and S poles alternately around the periphery and different in the optical axis direction.

Next, the operation of the above embodiment will be explained with reference to FIG. FIG. 3 is a schematic diagram of a lens barrel using the lens driving device of the first embodiment. First, the A-phase coil and the opposite A-phase coil are excited and assume the state shown in FIG. 3(a). Both ends of the movable part are attracted to different T magnets in the direction perpendicular to the optical axis.

Next, the B-phase coil and the opposite B-phase coil are energized, as shown in Figure 3 (
Take the state b). Parts rotated by 90° around the optical axis from the parts that were attracted in the previous state (FIG. 3(a)) are attracted to the electromagnets B and B. Similarly (c) =
In the order of (d)-(a), the movable part moves in the optical axis direction while changing the attraction.

FIG. 4 shows an example of a coil excitation sequence. The excitation sequence can be implemented by one-phase excitation, two-phase excitation, 1-2-phase excitation, microstep excitation, etc. similarly to known stepping motors.

As mentioned above, there are only a few moving parts at both ends! It contacts the magnet part and moves in the optical axis direction by changing the contact part around the optical axis. In other words, it moves in a spiral. Due to this spiral movement, the movable part of the IT electromagnet always has two contact points, and the friction becomes almost zero. Therefore, there is no loss of thrust generated due to sliding between the electromagnet part and the movable part, resulting in an efficient lens driving device.

In the second embodiment, a driving device is used in a lens barrel, and a fixed portion coil is wound around the optical axis.This embodiment will be explained using FIGS. 51 and 6.

FIG. 5 is a sectional view of a lens barrel using the lens driving device of the second embodiment. FIG. 6 is a perspective view of the coil and stator yoke, which are fixed parts. A fixing part 21 is fixed to the inner peripheral surface of the lens barrel 20. The fixed part 21 consists of a stator yoke 2223, a bobbin 24, and a coil 25, and the coil 25 is attached to the hobbin 24 as shown in FIG. and fix the stator yokes 22 and 23 so as to surround the coils. The salient pole portions 31 and 32 of the stator yoke 2223 are offset by exactly 180° so that they face each other on the inner peripheral side of the coil 25. At least two fixing parts 21 are provided on the inner peripheral surface of the lens barrel 20 in the optical axis direction so that the stator yoke salient pole parts 31 and 32 are deviated by 90 degrees around the optical axis. On the other hand, the movable part 26 is the same as that in the first embodiment, and consists of a hollow cylindrical member 27, an optical system holding member 28, and a lens 29. Reference numeral 27 denotes a hollow cylindrical member made of a magnetic material such as a plastic magnet, and both ends thereof are magnetized around the optical axis with S and N poles. The poles magnetized at both ends are different in the optical axis direction. Optical system holding member 2 is mounted on the inner periphery of hollow cylindrical member 27.
8 is fixed by adhesive or the like. The optical system holding member 28 does not have to be provided all around. The lens 29 is held by the optical system holding member 28.

It is clear that the driving device of the second embodiment operates in the same manner as the device of the first embodiment by energizing the coil. According to this embodiment, the number of coils is half that of the first embodiment, which is suitable for miniaturization. Also, like the first embodiment, the fixed part can be fixed due to the spiral movement! There are always two contact points in section a, and the friction is almost zero.

Therefore, there is no loss of thrust generated due to sliding between the fixed part and the movable part, resulting in an efficient lens driving device.

(Effects of the Invention) As explained above, according to the present invention, a plurality of coils whose applied voltages are sequentially switched are provided in the axial direction on the inner peripheral surface of the hollow cylindrical member, and a magnet is provided in the movable member. When the coils are sequentially energized, the movable member moves in the axial direction while making a spiral motion, and at this time, the movable member contacts the driving part, which is an electromagnet consisting of a coil, at only two points on the palm. Since surface contact does not occur, when the movable member is driven in the axial direction, there is no friction loss due to sliding as in the conventional case, and efficient driving can be achieved.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view showing a first embodiment in which the present invention is applied to a lens driving device, Fig. 2 is a cross-sectional view thereof, and Fig. 3 fa)
- (d) are schematic cross-sectional views showing the effects of the first embodiment;
The figure shows an example of a coil excitation sequence, FIG. 5 is a longitudinal sectional view similar to FIG. 1 showing the second embodiment, and FIG. 6 is an exploded perspective view of the coil and stator yoke that are the fixed parts thereof. . 1... Lens barrel 2... 6n material 3...
Coil 4...Movable member 5...Hollow cylindrical member 7...Lens 22.23...Stator yoke 24...Bobbin 25...Coil No. Figure 2' No. (a) (C) /4 (5) , -1 A phase/S pole, A phase: N pole B phase, B phase 0FF A phase: N pole A phase: S pole B phase, B phase: 0FF (b) (d) Δ phase, A phase: 0FF B phase, N pole, B phase, S pole A phase, A phase 0FF B phase, S pole, B phase: N pole

Claims (1)

[Claims] 1 Consisting of a hollow cylindrical member and a movable member movably arranged concentrically inside the cylindrical member, the inner peripheral surface of the hollow cylindrical member is capable of sequentially switching applied voltages. A drive device, characterized in that a drive unit including a plurality of coils is fixed in a direction perpendicular to a central axis, and a magnet is provided on an outer peripheral surface of the movable member in correspondence with the drive member.