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1. CIRCUIT DESCRIPTION
1 - 5 - 3 L A S E R O N O P E R A T I O N
Fig. 1 - 5 - 3 - 2 T i m i n g diagram for L A S E R O N T I M E .
Fig. 1-5-3-1
1 . W h e n a s i g n a l t o a c t i v a t e t h e laser is a p p l i e d t o pin 2 4 t o
2 7 of I C 1 5 ( T C 1 5 G or T 7 0 0 1 ) f r o m t h e s y s t e m c o n t r o l
m i c r o p r o c e s s o r , t h e level at pin 11 c h a n g e s f r o m " L " t o
" H " a n d t h e level at pin 3 of I C 1 6 also s w i t c h e s f r o m " L "
t o " H " .
2 . IC16 o u t p u t b e c o m e s + 5 V ( p o w e r s u p p l y v o l t a g e of
I C 1 6 : y
DD
) at pin 1 3 , w h e n i n p u t pin 3 is at " L " level.
W h e n t h e i n p u t is " H " level, t h e o u t p u t b e c o m e s o p e n .
T h e o u t p u t at pin 1 3 , h o w e v e r , b e c o m e s — 1 2 V , since it
is c o n n e c t e d w i t h a - 1 2 V line t h r o u g h R 2 3 0 .
3 . W h e n t h e v o l t a g e at pin 1 3 of I C 1 6 c h a n g e s f r o m + 5 V
t o - 1 2 V , Q 1 0 5 t u r n s O N . ( + 1 2 V is d i v i d e d by R 1 2 9
a n d R 1 3 0 t o p r o v i d e t h e e m i t t e r of Q 1 0 5 w i t h a b o u t 3 V .
W h e n t h e base v o l t a g e d r o p s b e l o w 3 V + 0 . 6 V , it m a k e s
Q 1 0 5 t u r n O N . ) Q 1 0 6 also t u r n s O N .
4 . W h e n Q 1 0 6 t u r n s O N , a v o l t a g e is d e v e l o p e d a c r o s s
R 1 3 5 c o n n e c t e d t o t h e c o l l e c t o r . Q 1 0 7 s w i t c h e s O N a n d
it d r a w s a c u r r e n t t h r o u g h t h e laser d i o d e t o e m i t laser
b e a m . W h e n t h e d i o d e e m i t s laser b e a m , a m o n i t o r d i o d e
p r o v i d e d in t h e p i c k u p a s s e m b l y w a t c h e s t h e laser e m i s
s i o n . T h e e m i s s i o n c a n be h e l d c o n s t a n t by c o n t r o l l i n g t h e
c u r r e n t t h r o u g h Q 1 0 7 w i t h a h e l p o f t h e m o n i t o r d i o d e .
5. Q 1 0 6 c o n s i s t s of t w o t r a n s i s t o r s w i t h t h e i d e n t i c a l
c h a r a c t e r i s t i c s , b e i n g u s e d u n d e r t h e s a m e c o n d i t i o n s
( s a m e e m i t t e r v o l t a g e a n d c u r r e n t ) . T h e r e f o r e , it f u n c t i o n s
t o p r o d u c e t h e s a m e base v o l t a g e . W h e n laser c u r r e n t
c o n t r o l R 1 2 8 is a d j u s t e d , t h e base v o l t a g e o f t h e o t h e r
t r a n s i s t o r is also a f f e c t e d (the v o l t a g e is d e t e r m i n e d by
R 1 2 3 , R 1 2 4 a n d t h e laser m o n i t o r d i o d e . )
T h e v a l u e s of R 1 2 3 a n d R 1 2 4 are p r o p e r l y s e l e c t e d
d e p e n d i n g o n t h e p i c k u p u s e d .
6. W h e n a v o l t a g e is i n c r e a s e d a c r o s s R 1 3 5 p l a c e d in the
c o l l e c t o r of Q 1 0 6 , it p r o v i d e s t h e base of Q 1 0 7 w i t h a
v o l t a g e in a c c o r d a n c e w i t h t h i s c o l l e c t o r v o l t a g e . T h e c o l
l e c t o r c u r r e n t of Q 1 0 7 c h a n g e s a c c o r d i n g l y , t h e r e b y c o n
t r o l l i n g t h e o u t p u t of t h e laser d i o d e .
7. W h e n t h e o u t p u t of t h e laser d i o d e i n c r e a s e s , t h e internal
resistance of t h e laser m o n i t o r d i o d e b e c o m e s s m a l l . T h e
base v o l t a g e of Q 1 0 6 g e t s h i g h e r , t h e r e b y r e d u c i n g the
c u r r e n t t h r o u g h Q 1 0 6 . T h e v o l t a g e a c r o s s R 1 3 5 in t h e
c o l l e c t o r c i r c u i t d r o p s a n d it p r o v i d e s t h e base of Q 1 0 7
w i t h a l o w e r v o l t a g e . Its c o l l e c t o r c u r r e n t is r e d u c e d t o p r o
d u c e less o u t p u t f r o m t h e laser d i o d e .
Summary of Contents for DP-1100 B
Page 3: ...D P 1 1 0 0 B II D P 1 1 0 0 B II I BLOCK DIAGRAM ...
Page 32: ...D P 1 1 0 0 B II 1 CIRCUIT DESCRIPTION Disc Scratch Dust RFES D C O N D O C K Fig 1 2A 3 5 ...
Page 112: ...2 IC OPERATION OF EACH CIRCUIT AND D P 1 1 0 0 B II PIN DESCRIPTION Fig 2 4 1 G 1 ...
Page 117: ...DP 1100B II I OPERATION OF MAIN MICROPROCESSOR Fig 3 1D Q data reading flow chart ...