JPH0197157A - Voice coil type actuator - Google Patents

Abstract

PURPOSE:To reduce leakage flux, to improve field efficiency and to make driving performance better, by clamping a magnet oriented in the radial direction with columnar two internal yokes in the position facing a driving coil. CONSTITUTION:A cylindrical magnet 8 oriented in the radial direction is clamped on its up- and downward surfaces with columnar internal yokes 9a and 9b in a cylinder holder 1 and arranged in the position facing a driving magnet 5. The flux 10 excited from the magnet 8 in the radial direction is perpendicularly intersected and it penetrates the driving coil 5. It passes from a projection 4a to an external yoke 4 and returns to the magnet 8 again through internal yokes 9a and 9b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a voice coil type actuator that controls the position of a photodetector, etc. in an optical disc playback device. [Prior Art] Fig. 2 is an internal configuration diagram of a conventional voice coil type actuator. It is supported by an external yoke 4 by a spring member 3 disposed vertically symmetrically in the axial direction. Reference numeral 5 denotes a drive coil wound around the outer peripheral surface of the cylindrical holder 1, and is arranged at a position facing the protrusion 4a of the external yoke 4. 6a and 6b are magnets arranged along the central axis of the cylindrical holder l;
Both magnets 6a and 6bFi have the same polarity facing each other, and an internal yoke 7 is located between the tips of the magnets 6a and 6b, facing the drive coil 5.

In the voice coil type actuator configured as described above, the magnetic flux lO excited in the axial direction from the magnets 6a and 6b repel each other in the internal yoke 7, so that it is converted to the radial direction and causes the drive coil 5 to be perpendicular to the winding direction. It becomes a magnetic path that passes through the external yoke 4 and returns to the magnets 6a and 6b again.

Thus, when a current is passed through the drive coil 5, the cylindrical holder l around which the coil 5 is wound receives a force in its axial direction, and the driven object 2 is Can be driven. The position of the driven object 2 can be controlled by changing the amount and direction of the current to the coil 5.

[Problem that the invention seeks to solve]

Since the conventional voice coil type actuator is configured as described above, the two opposing magnets 6a, 6
Since the magnetic flux excited in the axial direction from b forms a repulsive magnetic field, it must be forcibly bent in the radial direction and then perpendicular to the drive coil 5, which causes leakage of magnetic flux and reduces the efficiency of the magnetic field. There was a problem.

This invention was made in order to solve the above-mentioned problems, and is a voice fill type that forms a magnetic path where the magnetic flux excited from the magnet flows naturally without being forced to bend, thereby eliminating the generation of leakage magnetic flux. The purpose is to obtain an actuator.

[Means for solving problems]

The voice coil actuator according to the present invention has a radially oriented magnet sandwiched between two cylindrical internal yokes in a cylindrical holder, and the magnet is disposed at a position facing five drive coils.

[Effect]

In this invention, by sandwiching the magnet T oriented in the radial direction between two cylindrical internal yokes, the magnetic flux excited from the magnet is not forcibly bent and passes through the drive coil smoothly. A magnetic path can be formed.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is an internal configuration diagram of the voice coil type actuator according to the present invention, and since numerals 1 to 5 are the same as the conventional example explained in FIG. 2, their explanation will be omitted. Reference numeral 8 denotes a cylindrical magnet oriented in the radial direction.
is arranged at a position facing the drive coil 5.

The voice coil type actuator configured as described above has a magnetic flux 10 excited in the radial direction from the magnet 8.
passes orthogonally through the drive coil 5, forming a magnetic path from the protrusion 4a, through the outer yoke 4, through the inner yokes 9a and 9b, and back to the magnet 8. That is, in this invention, by adopting a configuration in which the magnet 8 oriented in the radial direction is sandwiched between the internal yokes 9a and 9b, a smooth magnetic flux is formed that transmits from the magnet 8 to the drive coil 5, and therefore there is less leakage magnetic flux. Become something. When current is applied to the drive coil 5 in this state, the cylindrical holder l around which the coil 5 is wound will receive a force in the axial direction due to Fleming's left-hand rule from the relationship with the magnetic flux 10 perpendicular to the coil, and the driven object will receive a force in the axial direction. Drive 2.

Note that by shielding the actuator according to the present invention with a magnetic material except for the minimum necessary opening of the outlet (not shown) for the driven object 2, magnetic disturbance to external equipment can be prevented.

〔Effect of the invention〕

As explained above, according to the present invention, the radially oriented magnet is sandwiched between two cylindrical internal yokes at a position facing the drive coil, so that smooth magnetic flux from the magnet to the drive coil is achieved. Nasi,
This results in a voice coil type actuator with less leakage magnetic flux, improved magnetic field efficiency, and good drive performance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an internal configuration diagram of a voice coil type actuator according to the present invention, and FIG. 2 is an internal configuration diagram of a conventional ZI coil type actuator. l... Cylindrical holder, 2... Driven object, 3... Spring member, 4... External yoke, 5... Drive coil, 8...
...Magnet, 9a, 9b...Internal yoke. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) A cylindrical internal yoke, a cylindrical holder that holds a driven object and has a drive coil wound around its outer periphery, and an external yoke are arranged in a circular shape, and the internal yoke is held by a magnet, A voice coil type actuator in which the holder is supported by a spring member, wherein the magnet is oriented in a radial direction and is held by an internal yoke at a position facing a drive coil. (2) The voice coil type actuator according to claim 1, characterized in that the spring members are vertically symmetrically arranged with respect to the center line direction of the cylindrical holder. (3) The voice coil type actuator according to claim 1, wherein the voice coil actuator is shielded with a magnetic material except for the minimum necessary opening of the outlet for the driven object.