FERROFLUID IN OPTICAL DISC PICKUP ACTUATORS
Ferrofluidics are becoming increasingly popular for use for actuator
damping in a variety of devices including CD players, Laser Disc
players, CD-ROM drives and, DVD-ROM drives.
actuator in such a device is an electro-mechanical device comprised
of two magnetic circuits and two discreet coils, oriented perpendicular
to each other. The coils and objective lens are mounted on an integral
bobbin/carrier assembly which, in turn, is suspended in the magnetic
air gaps by four strands of Beryllium Copper wire. The suspension
is damped by the presence of silicone rubber at its termination.
In spite of the presence of the silicone rubber
"damper bond", the actuator still exhibits a strong mechanical
resonance which affects its settling time and vibrational characteristics.
This resonance can cause errors in reading information from the
disk, particularly in high speed CD-ROM and DVD-ROM drives.
Ferrofluid is used to dampen vibration in various commercial dampers
as well as in consumer audio loudspeakers and CD/DVD-ROM devices.
Ferrofluid damping is very reliable as the viscosity and retention
capability of the fluid can be easily controlled to meet device
requirements. In addition to the damping benefits in audio loudspeakers,
ferrofluid also provides an efficient heat transfer medium to conduct
heat away from the coil.
In the actuator design, ferrofluid is applied to
the surface of the magnets until the quantity is sufficient to maintain
intimate contact with the bobbin/carrier assembly. The fluid is
retained in the magnetic field and its viscosity provides the desired
mechanical resistance (damping) to the moving assembly. This improves
the actuator's settling time and vibrational characteristics. Access
time is also improved, particularly on warped or eccentric discs.
Developed specifically for optical pickup actuators,
the CF Series of ferrofluids posses the necessary wide temperature
range, colloid stability and low volatility required for long term
performance in these applications. Please call for full specifications
for the CF Series of fluids.
Ferrofluid | Vacuum
Feedthroughs | Thermoelectric Modules
Contract Manufacturing | Literature
Rack | Specialty Seals
Inertia Dampers | Electron