JP3420577B2 - Linear actuator and lens driving device using linear actuator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear actuator and a lens driving device using the linear actuator, and more specifically, in an inner focus type zoom mechanism, a zoom motor for a zoom motor is provided so as not to be out of focus during zoom operation. The present invention relates to a zoom mechanism that moves a focus lens along with movement.

[0002]

2. Description of the Related Art In recent home video camera lenses, products using an inner focus system have become mainstream in order to reduce the size and weight. In this inner focus method, since the focus surface moves depending on the zoom position, when moving the zoom lens, it is necessary to move the focus lens as well. Therefore, the zoom speed is affected not only by the limitation of the zoom motor but also by the speed of the focus motor that drives the focus lens. At present, stepping motors are mainly used as focus lens drive motors, but there is a limit to the speed of the focus motor from the viewpoint of power consumption and noise, and a focus motor capable of higher speed is required. Has become.

FIG. 4 is an exploded perspective view of essential parts for explaining an example of a linear motor for a video camera proposed to solve the above problems (Technical Report V of the Institute of Television Engineers of Japan).
OL17, No. 5) "Development of linear motor for video camera"), a drive coil 21, a magnet 22 and a yoke 23 are arranged so as to surround the outer periphery of the focus lens 20 as shown in the figure, and further, a speed sensor is a movable part. A sensor coil 24 is attached to the focus lens side, and a velocity detecting magnet 25 different from the lens driving magnet 22 is attached to the fixed side. 26, 2
Reference numeral 7 denotes a main shaft and a guide shaft that slidably hold the movable portion. By supplying an electric current to the drive coil 21, the focus lens 20 that is the movable portion reciprocates along the shafts 26 and 27, and the focus length 20. The lens drive motor is realized at high speed and with less noise.

[0004]

According to the above-mentioned prior art, it is possible to uniformly apply thrust to the entire lens, but the driving coil and the speed sensor coil are the movable parts of the focus. Since it is on the lens side, it has the following drawbacks.

Stress is applied to the electrode wire of the coil.

A driving magnet and a speed sensor magnet are required separately.

Since the motor and the lens are integrated, the structure is complicated and the manufacturing cost is increased.

The magnet must be arranged so as to wrap the entire focus lens, and the whole lens becomes heavy.

[0009]

The present invention SUMMARY OF THE INVENTION In order to solve the above problems, in the linear actuator of the first aspect of the present invention, covered with the movable magnetic body, the movable magnetic body, for driving said movable magnetic body And a bobbin around which a drive coil for winding is wound, wherein a current flows through the coil to axially reciprocate the movable magnetic body in the bobbin, the bobbin further includes the drive coil. It has a detection coil covering, the driving coil and the detection coil
Is that is fixed to the bobbin.

[0010] The second lens driving device using the linear actuator of the present invention, a movable magnetic body, covering the movable magnetic body, a bobbin driving coil for driving the movable magnetic body is wound The bobbin further has a detection coil covering the drive coil,
Wherein the detection coil is fixed to the bobbin has a linear actuator for reciprocating the movable magnetic body axially within said bobbin by applying a current to the driving coil, the lens supporting member for supporting the lens, the movable A magnetic body is coupled to the lens holding member, and the movable magnetic body drives the lens.

[0011]

[Function] A magnetic body (magnet) is made movable, a shaft for driving a lens is integrated with the movable magnet, and a drive coil for moving the magnet is fixed.
While not applying stress to the electrode and electrode wire of the drive coil, the change of the magnetic field due to the movement of the movable magnet is detected by the coil for the speed sensor, thereby eliminating the need for the magnet for the speed sensor. Further, the lens portion and the lens driving portion can be designed independently by connecting the lens portion to the shaft.

[0012]

1 is a view for explaining an example of an actuator according to the present invention. FIG. 1 (a) is an axial sectional view (a sectional view taken along the line AA of FIG. 1 (b)). Figure 1 (b)
1A is a sectional view taken along the line BB of FIG. 1A, in which 1 is a magnetic body (hereinafter, magnet) that is a movable body, 2 is a fulcrum plate attached to both ends or one end of the magnet 1, and 3 is Support plate 2
A shaft 4 made of resin, for example, attached to one side of the bobbin 4 covers the magnet 1 and has a drive coil 5 for driving the magnet 1 and a sensor coil 6 provided outside the drive coil 5. Is.

The fulcrum plate 2 is formed to have a diameter larger than that of the magnet 1, is supported by the inner wall of the bobbin 4, and has a shaft 3 extending axially from one of the fulcrum plates.
Is provided.

At the tip of the shaft 3, there is formed a projection 3a having a shape capable of being joined to a lens portion which is a driven body.

5a is an electrode terminal of the drive coil, 6a
Is the electrode terminal of the sensor coil 6, and 10 is the entire actuator configured as described above.

FIG. 2 is a diagram for explaining the coupling between the actuator 10 and the lens portion constructed as described above.
First, the lens 20 is supported by the lens supporting member 11, and the lens supporting member 11 is supported by the shaft 12 so as to be movable in the arrow A direction.

The lens support member 11 is provided with a clamper 13 at one end and a sensor 14 for detecting the movement of the lens 20 at the other end.

The clamper 13 is connected by the projection 3a of the shaft 3 shown in FIG. 1, whereby the actuator 10 shown in FIG. 1 and the lens portion 20 are connected,
Thereby, the movement of the movable magnet 1 can be transmitted to the lens 20.

The movement of the movable magnet 1 is detected by detecting the change in the magnetic field due to the movement by the sensor coil 6, and the detection output thereof controls the drive current applied to the drive coil 5 to cause the movement of the movable magnet 1.
The speed of is controlled.

The electrodes 5a, 6a of the drive coil 5 and the speed detecting coil 6 shown in FIG. 1 can be taken out from the outer surface of the actuator 10, and since the coil portion is fixed, these electrodes 5a, 6a can be taken out. 5a, 6a and electrode wire 5
No stress is applied to b and 6b.

Although FIG. 2 shows an example of a sensor composed of the light emitting element 14 and the light receiving element 15 as a sensor for detecting the position of the lens, these are not directly related to the present invention, and therefore detailed description will be given. Is omitted.

FIG. 3 shows an actuator 10 according to the present invention.
2 is a diagram illustrating an example of a case where the stepping motor 30 is used to drive the lens unit having the configuration illustrated in FIG. 2. As illustrated, the rotation of the stepping motor 30 is screwed off. The rotation of the shaft 31 is transmitted to the clamper 13 when the rotation of the shaft 31 is screwed with the screw of the shaft 31, and the lens 20 is moved in the arrow A direction.

As described above, the lens portion can be driven by using the actuator according to the present invention or the stepping motor, and the lens can be driven even if the driving source is the actuator or the stepping motor. The mechanism can be the same as in the case of FIG. 1, and there is an advantage that the mechanical design using the stepping motor and the design using the actuator proposed in the present invention can be largely shared.

[0024]

As is apparent from the above description, according to the present invention, (1) since the drive coil and the speed detection coil can be arranged on the fixed side, stress is not applied to the electrodes of these coils. In addition, there are few failures and the life can be extended.

(2) Since the driving magnet and the speed detecting magnet can be shared, the structure is simplified and the manufacturing cost can be reduced.

(3) Since the actuator and the lens have different structures and are simply connected to each other, they can be designed separately, which makes designing and manufacturing very easy and low cost. You can

(4) Since the focus lens and the coil for driving the focus lens are provided separately, the weight of the movable lens part can be reduced and the lens can be moved more smoothly. And so on.

[Brief description of drawings]

FIG. 1 is a main part configuration diagram for explaining an embodiment of an actuator according to the present invention.

FIG. 2 is a diagram for explaining an example of driving a focus lens using the actuator shown in FIG.

FIG. 3 is a diagram illustrating an example of a case where a focus lens is driven by using a stepping motor.

FIG. 4 is a diagram for explaining an example of a conventional focus lens drive mechanism.

[Explanation of symbols]

1 ... Movable magnet, 2 ... Support plate, 3 ... Shaft, 4 ...
Bobbin, 5 ... Drive coil, 6 ... Speed detection coil, 10 ...
Actuator, 11 ... Lens support member, 12 ... Lens moving shaft, 13 ... Clamper, 14, 15 ... Lens position sensor, 20 ... Lens, 30 ... Stepping motor, 31 ... Screw shaft.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02K 33/16 G02B 7/04

Claims (2)

(57) [Claims] 1. A cover and the movable magnetic body, the movable magnetic body, said
And a bobbin around which a drive coil for driving the movable magnetic body is wound, and a current is passed through the coil to reciprocate the movable magnetic body in the bobbin in the axial direction. in the bobbin have a detection coil to cover the driving coil, the driving coil and the
Linear actuator detection coil characterized that you have been fixed to the bobbin. 2. A cover and the movable magnetic body, the movable magnetic body, said
And a bobbin in which the driving coil for driving the movable magnetic member is wound, said bobbin having a detection coil to cover the driving coil, the driving coil and the detecting co
Yl is fixed to the bobbin has a linear actuator for reciprocating axially the movable magnetic member within said bobbin by applying a current to the driving coil, the lens supporting member for supporting the lens, the movable magnetic body Is coupled to the lens holding member, and the movable magnetic body drives the lens. A lens drive device using a linear actuator.