Method to Reduce Power Consumption of Compact Disk-Read Only Memory Drive by Using Free Run Braking
Original Publication Date: 1998-Jan-01
Included in the Prior Art Database: 2005-Apr-04
Sawada, Y: AUTHOR [+1]
Disclosed is a method for reducing power consumption for CAV (Continuous Angular Velocity) servo controlled CD-ROM drives.
Method to Reduce Power Consumption of Compact Disk-Read
Drive by Using Free Run Braking
a method for reducing power consumption for CAV
(Continuous Angular Velocity) servo controlled CD-ROM drives.
conventional CD-ROM drives are generally CLV (Continuous
Liner Velocity) servo controlled, so that disk rotation speed needs
to be changed depending on the track being read. To improve access
time and overall data transfer rate in this circumstance, prompt
spin-up and spin-down of spindle motor are required at a cost of
In CAV, this
is no longer required. No spin-ups and
required when continuously reading from tracks that are apart.
However, when a drive completes a Read command and spins down to
enter Standby mode, the disk is often being forced to stop by the
same braking method used in CLV spin down. This is due to the
remainder of CLV method architected in Motor Driver and DSP (Digital
Servo Processor) for CD-ROM drives.
The Figure shows the configuration of the
CD-ROM drive in
accordance with this invention, which reduces power consumption by
using free run braking. The CD-ROM drive's Motor Driver IC
(Integrated Circuit) has a voltage controlled speed control input.
When V-cntr is lower than V-ref the motor reduces speed (braking
takes place), and when V-cntr is higher than Vref, the motor
increases speed. This is controlled by the DSP. In this method,