JPH08223897A - Drive device using linear actuator - Google Patents

Abstract

(57) [Abstract] [Purpose] The magnet is movable and the drive coil is fixed,
Stress is not applied to the electrode of the coil and the electrode wire, and the movement of the magnet is detected by the sensor coil, so that the magnet is driven and shared by the sensor. [Configuration] A magnetic body (magnet) 1 as a movable body,
The magnetic body 1 is covered with a bobbin 4 as a fixed body around which a drive coil 5 is wound. A current is passed through the coil 5 to move the magnetic body 1 inside the bobbin 4. Reciprocate in the direction. The magnetic body 1 has a fulcrum plate 2 that is larger than the diameter of the magnetic body 1 and is supported by the inner wall of the bobbin 4 at both ends or one end thereof, and a resin that extends axially from one end of the magnetic body 1. The shaft 3 is integrally formed. The tip of the shaft 3 has a connecting portion 3a to which a driven object is connected, and the driven object is connected to the connecting portion 3a. The sensor coil 6 detects the movement of the magnetic body 1.

Description

Detailed Description of the Invention

[0001]

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

[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. Currently, a stepping motor is mainly used as a focus lens drive motor, but there is a limit to how fast the focus motor can be in terms of power consumption and noise. Has become.

FIG. 4 is an exploded perspective view of an essential part for explaining an example of a linear motor for a video camera proposed to solve the above problems (Technical Report VOL.
17, No. 5 "Development of linear motors for video cameras")
As shown in the figure, 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, and further, as a speed sensor, a sensor coil 24 is provided on the side of the focus lens which is a movable part, and a sensor coil 24 is provided on the fixed side. A speed detecting magnet 25 different from the lens driving magnet 22 is attached. Reference numerals 26 and 27 denote a main shaft and a guide shaft for slidably holding a movable part, which are drive coils 2
By passing a current through the focus lens 20, the movable part of the focus lens 20 is reciprocated along the shafts 26 and 27 to move the focus length 20 in a straight line. Has been realized.

[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 coil electrode wire. A drive 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 placed so as to wrap the entire focus lens, which makes the entire lens heavy.

[0005]

In order to solve the above-mentioned problems, the present invention provides (1) a magnetic body as a movable body and a drive coil for covering the magnetic body and driving the magnetic body. And a bobbin as a fixed body that is wound, and comprising a linear actuator that causes a current to flow in the coil to drive the magnetic body to reciprocate in the axial direction in the bobbin,
The magnetic body that is the movable body has a fulcrum plate that is larger than the diameter of the magnetic body and that is supported by the inner wall of the bobbin at both ends or one end of the magnetic body. It has integrally a shaft formed of an extending resin or the like, and has a connecting portion at the tip of the shaft to which a driven object is connected, and when the driven object is connected to the connecting portion, The magnetic body is held by the fulcrum plate attached to the end of the magnetic body and the connecting portion attached to the tip of the shaft. Further, (2) In the drive device according to (1), the bobbin further has a detection coil that covers the drive coil, the detection coil detects a change in a magnetic field due to the movement of the magnetic body, and a speed of the magnetic body is detected by the detection signal. Control Is obtained is characterized in that the the.

[0006]

[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.

[0007]

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 an inner wall of the bobbin 4, and is provided with a shaft 3 extending in the axial direction from one of the fulcrum plates. Further, a projection 3a having a shape capable of being joined to a lens portion which is a driven body is formed at the tip of the shaft 3. In addition, 5a is an electrode terminal of the drive coil, 6
Reference symbol a indicates an electrode terminal of the sensor coil 6, and reference symbol 10 indicates 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. This lens support member 11
Has a clamper 13 at one end and a lens 2 at the other end.
A sensor 14 for detecting the movement of 0 is provided. The clamper 13 is coupled with the protrusion 3a of the shaft 3 shown in FIG. 1, so that the actuator 10 shown in FIG. 1 and the lens unit 20 are coupled with each other. Can be told. The movement of the movable magnet 1 is detected by detecting a 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 detection 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 and electrode wire 5
No stress is applied to b and 6b. Although FIG. 2 shows an example of the sensor including the light emitting element 14 and the light receiving element 15 as the sensor for detecting the position of the lens, these are not directly related to the present invention, and thus detailed description thereof will be 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 unit can be driven by using the actuator according to the present invention or the stepping motor, and the lens mechanism can be designed even if the driving source is the actuator or the stepping motor. The mechanical design using the stepping motor and the design using the actuator proposed in the present invention have a merit that they can be largely common to each other.

[0011]

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) The actuator and the lens have different structures, and simply
Since they are connected to each other, they can be designed separately, which makes designing and manufacturing very easy and can reduce the cost. (4) Since the focus lens and the coil for driving the focus lens are provided separately, the lens part that is a movable part can be made lighter, 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.

Claims (2)

[Claims] 1. A magnetic body as a movable body, and a bobbin as a fixed body that covers the magnetic body and around which a drive coil for driving the magnetic body is wound. A linear actuator is provided which drives the magnetic body to reciprocate in the axial direction in the bobbin by passing an electric current. The magnetic body which is the movable body has a diameter larger than the diameter of the magnetic body at both ends or one end thereof. It has a fulcrum plate supported by the inner wall of the bobbin, and integrally has a shaft made of resin or the like that extends axially from one end of the magnetic body, and the tip of the shaft is covered. A connecting part to which a driving object is connected; and when the driven object is connected to the connecting part, the fulcrum plate attached to the end of the magnetic body and the connection attached to the tip of the shaft. And the magnetic body A drive device using a linear actuator that is held. 2. The drive device according to claim 1, wherein the bobbin further has a detection coil covering the drive coil, the change in the magnetic field due to the movement of the magnetic body is detected by the detection coil, and the detection signal is used to detect the change in the magnetic field. A drive device using a linear actuator characterized in that speed control of a magnetic body is performed.