CD Player Control & TrackingOverall construction of a CDTracking System of CDSlide 4Slide 5Slide 6Slide 7Misalignment DetectionSlide 9Slide 10Slide 11ReferenceCD Player Control & TrackingCD Player Control & TrackingEce-e 443Ece-e 443Kai Chung WongKai Chung WongOverall construction of a CDOverall construction of a CD120mm diameter disk of polycarbonate 120mm diameter disk of polycarbonate plasticplasticActive Data starts at 46mm, ends at 117mmActive Data starts at 46mm, ends at 117mm““Pits” and “Lands” represent the dataPits” and “Lands” represent the dataData is circling from inside to outsideData is circling from inside to outsideEach track is approximate 0.5um wide, with Each track is approximate 0.5um wide, with 1.6um separating each track1.6um separating each trackTracking System of CDTracking System of CD •Spindle motorSpindle motor•Radial tracking driveRadial tracking drive•Focusing actuatorFocusing actuatorSpindle motor:Spindle motor:Control speed of rotating disc. Speed is Control speed of rotating disc. Speed is regulated, mainly to maintain a linear reading regulated, mainly to maintain a linear reading speed.speed.Two ModeTwo ModeConstant Linear Velocity(CLV)Constant Linear Velocity(CLV)V constantV constantMotor must rotate slower as the laser Motor must rotate slower as the laser moves towards the outside edge of discmoves towards the outside edge of discConstant Reading VelocityConstant Reading VelocityConstant Angular Velocity(CAV)Constant Angular Velocity(CAV)W constantW constantMotor speed constantMotor speed constantData transfer rate is higher in outer tracks Data transfer rate is higher in outer tracks then inner tracksthen inner tracksV r Radial Tracking Motor:Radial Tracking Motor:Move the focus lens to different distances Move the focus lens to different distances radially along the disc to read different radially along the disc to read different tracks.tracks.Move slowly radially outwards as the disc Move slowly radially outwards as the disc progresses from start to finishprogresses from start to finishFocusing Actuator:Focusing Actuator:Made by coil of wires, very low torqueMade by coil of wires, very low torqueMoves the focus lens up and down in order for Moves the focus lens up and down in order for the light to maintain a steady focus on the tracks. the light to maintain a steady focus on the tracks.MisalignmentMisalignment Detection DetectionMain