JP2559097Y2 - Drive - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small moving coil type actuator, for example, a drive device for performing fine focusing of a CD pickup, and more particularly to an improvement of a rare earth sintered magnet for excitation incorporated in the drive device. .

[0002]

2. Description of the Related Art FIG. 1 is a perspective view of a main part of a CD pickup device. In FIG. 1, reference numeral 1 denotes an opposing magnet for excitation, 2 a focus coil for operating the lens 4 in a vertical direction in a magnetic field generated by the magnet 1 for excitation, and 3 a lens 4 in a magnetic field generated by the magnet 1 for excitation. The tracking coils 5 operating in the front-rear direction are current supply wires, and support the focus coil 2 and the tracking coil 3. Excitation magnet 1 and current supply wire 5
Is usually as narrow as about 0.5 to 1.0 mm. Conventionally, a high performance rare earth sintered magnet has been used as the excitation magnet 1. In particular, rare earth / iron / boron magnets, which are inexpensive and have high magnetic properties, have been used recently. These rare earth / iron / boron magnets are inexpensive and have high magnetic properties, but they are easily rusted, so they have been used with a highly conductive metal coating such as Ni plating.

[0003]

When the rare earth magnet whose surface is covered with a conductive film is used as the magnet for excitation, the following problems occur. That is, the interval between the exciting magnet 1 and the current supply wire 5 is usually 0.5 to
Since it is as narrow as about 1.0 mm, the excitation magnet 1 may come into contact with the current supply wire 5 due to external vibration, excessive amplitude of the coil, and the like. At this time, an overcurrent may flow through a coil driving power supply (not shown) to damage the element or cause malfunction of the apparatus, for example, a reading error may occur. Therefore, an object of the present invention is to provide a drive device that does not cause a malfunction of the device even when external vibrations or the like occur, for example, a reading error.

[0004]

SUMMARY OF THE INVENTION The present invention provides a conductor having both a power supply function and a support function, a movable coil supported by the conductor, and a rare earth permanent magnet for exciting the movable coil when the movable coil is energized. In a driving device having a magnet, the above-mentioned problem is solved by forming an electrically insulating coating on the outer periphery of the rare earth permanent magnet for excitation. That is,
It is difficult to mechanically prevent the contact between the current supply wire and the excitation permanent magnet due to vibration or the like, because it causes an increase in the size of the device or the like. This problem was solved by electrically insulating the surface of the permanent magnet so as not to cause any trouble.

[0005]

The structure can be applied to a small device by using a high performance rare earth magnet, and has a structure in which short-circuit current does not flow even when the power supply line and the permanent magnet are in contact with each other due to the insulation resistance of the coating material. This prevents an overload from being applied to the coil driving current source, and prevents a failure from occurring. It is desirable that the thickness of the electrical insulating film is 1 μm or more to ensure reliability.

[0006]

1 and 2 are schematic views of a CD pickup device according to the present invention. FIG. 1 is a perspective view and FIG. 2 is a side view thereof. 1 and 2, reference numeral 1 denotes an opposing exciting magnet, 2 denotes a focus coil that operates a lens 4 in a vertical direction in a magnetic field generated by the exciting magnet 1, and 3 denotes a lens in a magnetic field generated by the exciting magnet 1. Reference numeral 4 denotes a tracking coil which operates in the front-rear direction, and reference numeral 5 denotes a current supply wire, which supports the focus coil 2 and the tracking coil 3. In this embodiment, the excitation magnet 1 is used.
The resin was vacuum-deposited (Parylene coating) on the surface. The thickness of the resin on the surface is 2 to 5 μm, but the insulation strength is 250 V DC, 100 MΩ or more. By using the above magnet, the equipment failure due to the short wire could be eliminated. The same effect was obtained regardless of the material of the magnet, whether samarium / cobalt or neodymium / iron. In addition, even when the surface was electrodeposited with an epoxy resin (8 to 20 μm), the insulation was DC 250 V, 100 MΩ or more, and the same effect was obtained. Further, these coatings had sufficient adhesion strength and corrosion resistance.

[0007]

According to the present invention, electrical insulation on the surface of the rare earth magnet is ensured, and the reliability of rare earth magnet applied equipment can be expected to be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a CD pickup device according to the present invention.

FIG. 2 is a side view of the CD pickup device according to the present invention.

[Explanation of symbols]

1 magnet for excitation 2 focus coil 3 tracking coil 4 lens 5 current supply wire

Claims (2)

(57) [Scope of request for utility model registration] 1. A drive device comprising: a conductor having both a power supply function and a support function; a movable coil supported by the conductor; and an exciting rare earth permanent magnet for driving the movable coil when the movable coil is energized. A drive device, wherein an electrical insulating film is formed on a surface of the exciting rare earth permanent magnet. 2. The driving device according to claim 1, wherein the electric insulating film has a thickness of 1 μm or more.