Fixed support for voice coil motor

Details Fixed support for voice coil motor Fixed support for voice coil motor

2000-01-20

2001-10-16

Ramirez, Nestor (Department: 2834)

Freight accommodation on freight carrier

Particular article accommodation

Wheeled vehicle

C360S265700

Reexamination Certificate

active

06302626

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a Voice Coil Motor (VCM), and more particularly to a fixed support for voice coil motor.
BACKGROUND OF THE INVENTION
A fixed support of voice coil motor is a base for winding coil thereon. One conventional fixed support is shaped like a plate, from which several pins extrude for receiving winded coil. For a better rigidity, the plate of fixed support is usually machined in a relatively great thickness. However a fixed support with thick plate will reduce the density of magnetic flux through the plate, which is generated by pairs of permanent magnets at each side of the plate, thereby lowering output power of the voice coil motor adopting the fixed support. Even if the thickness of the plate was simply thinned out, the rigidity of the plate would be degraded, thus making this change unlikely. Another fixed support is formed together with coil by an injection mold. Through the fixed support could be machined much thinner than the forgoing one, it suffers financial burden due to the high cost of the injection mold. In many cases, when cost turns to a crucial issue, the fixed support manufactured by injection mold will not be a cost efficient one anymore. Thus, there is a huge need to provide a fixed support with a plate as thin as possible, while maintaining its cost competitiveness.
FIG. 1
shows a conventional fixed support of voice coil motor, which includes a plate
30
, several pins
10
extruding from the plate
30
, and coil
20
winded around the pins
10
. As a result of the wide thickness of the plate
30
of fixed support, the magnetic flux density, which is generated by pairs of permanent magnets from each side of the plate
30
, is relatively low, therefore, reducing output torque of the voice coil motor adopting the fixed support. Moreover, as the mass distribution along the transverse direction of plate
30
remains asymmetric, the fixed support would likely vibrate fiercely when the voice coil motor rotates.
FIG. 2
shows another conventional design for fixed support
40
of voice coil motor. The fixed support
40
is fabricated much thinner than the above mentioned one through an injection mold. The Coil
50
is winded inner the fixed support
40
, so as to ensure the fixed support to remain in a thin thickness and a relatively balanced mass distribution. Although the fixed support
40
provides better performance for voice coil motor than the above one does, its exists several shortcomings. Owing to the high cost of injection mold and complication of winding coils for various shaped fixed supports, the fixed support
50
will hard to be cost efficient unless manufacturing it in mass production.
SUMMARY OF THE INVENTION
This invention discloses a fixed support for voice coil motor comprising a coil, hollow plate, opening, structural reinforcement beam, and a plurality of pins. The pins extruding from the hollow plate allows the coil to wind around them, and the structural reinforcement beam improves stiffness of the fixed support. In addition, all the pins and structural reinforcement beam are carved out form the hollow plate. The opening, which locates on the center of the hollow plate, distributes stress concentration around the center.
For many voice coil motors, the present fixed support provides the following advantages such as, an improved stiffness, better heat release efficiency, easier manufacturing process, and decreased cost. Therefore, this invention would successfully overcome the aforementioned disadvantages caused by conventional fixed supports.


REFERENCES:
patent: 6061206 (2000-05-01), Foisy et al.

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