Kenwood DP-1100 B Service Manual page 11

D P - 1 1 0 0 B II
1-7 C O M P A C T D I S C ( C D )
1 . T h e r e are m a n y kinds of D A D s y s t e m s : C D , M D a n d
A H D . (Refer t o Fig. 1.10)
2 . D P - 1 1 0 0 B / I I a d o p t s t h e CD s y s t e m . T h e CD system is
also c a l l e d " a light s y s t e m " . A
s e m i c o n d u c t o r laser is c o n v e r g e d w i t h an objective lens
t o hit pits inside a disc for using their reflected light.
3 . T h e r e are no g r o o v e in t h e CD s y s t e m hit pits.
Size of Pit: W i d t h
D e p t h : 0 . 1 /im
4 . Laser b e a m is hit t h r o u g h a t r a n s p a r e n t disc layer t o read
o u t d a t a . (See Fig. 1.11)
5. C o n s t r u c t i o n of disc. (See Fig. 1.11)
6 . Disc baseplates are usually m a d e of PC ( p o l y c a r b o n a t e ) ,
P M M A (acryl) is superior f o r a disc baseplate, b u t its
Reflecting Surface
1 4
II. FUNDAMENTALS
light b e a m f r o m a
0 . 5 fim, L e n g t h : 0 . 9 t o 3 . 3 / i m ,
1.5 /tm
Protective Surface
1.2
mm
Approx. 1 mm0
CD System
Fig.
Laser Beam
1 mm0
m o i s t u r e a b s o r p t i o n c a u s i n g b e n d is a big d e f e c t . (Refer
t o p r e c a u t i o n s o n h a n d l i n g t h e disc.)
7. Playback t i m e is 6 0 m i n u t e s w i t h a 1 2 0 m m disc.
D i m e n s i o n s are given in Fig. 1 . 1 2 .
8. T h e rotating s p e e d of t h e disc is n o t c o n s t a n t . Because of
a c o n s t a n t linear v e l o c i t y system e m p l o y e d , the rotating
s p e e d is varied b e t w e e n a r o u n d 5 0 0 t o 2 0 0
( c o u n t e r c l o c k w i s e )
c a p s t a n drive t y p e t a p e r e c o r d e r C A V ( c o n s t a n t a n g u l a r
v e l o c i t y ) : rim drive t y p e t a p e r e c o r d e r .
9. PL) (pickup) d o e s n o t c o n t a c t a disc surface b u t t r a c e s a
t r a c k m o v i n g f r o m inner radius t o outer radius.
1 0 . H o w m u c h effectively d o e s it use a laser beam?
It d e p e n d s u p o n the t r a n s m i s s i o n f a c t o r , reflection f a c t o r
a n d d o u b l e r e f r a c t i o n .
0 . 9 - 3 . 3 nm
Pit
nm
0.4
Reproduction Light Spot
Transparent Plastic
Objective Lens
1 . 1 0
1.6 /tm
Fig. 1-11
CLV ( c o n s t a n t linear
nm
0.11
Disc Baseplate (Polycarbonate)
Reflecting Film (Aluminium)
Protective Film
r . p . m .
v e l o c i t y ) :