CD Player Control

1
CD Player Control Tracking

• Ece-e 443
• Kai Chung Wong

2
Overall construction of a CD

• 120mm diameter disk of polycarbonate plastic
• Active Data starts at 46mm, ends at 117mm
• Pits and Lands represent the data
• Data is circling from inside to outside
• Each track is approximate 0.5um wide, with 1.6um
  separating each track

3
Tracking System of CD

• Spindle motor
• Radial tracking drive
• Focusing actuator

4

• Spindle motor
• Control speed of rotating disc. Speed is
  regulated, mainly to maintain a linear reading
  speed.
• Two Mode
• Constant Linear Velocity(CLV)
• V constant
• Motor must rotate slower as the laser moves
  towards the outside edge of disc
• Constant Reading Velocity
• Constant Angular Velocity(CAV)
• W constant
• Motor speed constant
• Data transfer rate is higher in outer tracks then
  inner tracks

5

• Radial Tracking Motor
• Move the focus lens to different distances
  radially along the disc to read different tracks.
• Move slowly radially outwards as the disc
  progresses from start to finish

6

• Focusing Actuator
• Made by coil of wires, very low torque
• Moves the focus lens up and down in order for the
  light to maintain a steady focus on the tracks.

7
(No Transcript)
8
Misalignment Detection
9
Main Bean
10
(No Transcript)
11

• Questions?

12
Reference

• http//www.andrew.cmu.edu/user/cchao/resume/2_theC
  Dsystem.htm
• http//www.bcae1.com/cdplayer.htm
• http//www.howstuffworks.com./cd.htm/printable
• http//dutch.phys.strath.ac.uk/CommPhys2001Exam/Al
  lison_Rice/CD.htm
• http//www.ee.washington.edu/conselec/CE/kuhn/labs
  /lab4a.htm