Epson TM200 - Page 24

TM200 Service Manual
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CP U per i p heral l o gi c ci rcu i t s
RA M (128K byte )
R A M i s used f o r t e mpor ary stor ag e of th e f o ll owi n g:
 Data recei v e d fr om the i n t e rface ( r ecei v e b u ffer )
 Pa tt ern d a t a pr int e d b y the pri n t head uni t (p ri nter b u ff er )
 Da ta used f o r CPU r out ine s ( f l a gs, poi n ter s , et c.)
Fla s h memo ry (2M or 8M bit s )
A p r i n ter cont ro l p r ogram an d cha rac t er gener at or d a t a i s wri tt en int o fl ash memory.
The
co ntr o l pro gra m contr o l s b a sic p r i n ter op erat io ns, and all CPU cont rol is
perfo r med in ac cord anc e wit h th is p r og ram. Another flash m e mor y wor k s as a
sub
- memor y for such i t ems as e x p a nding char a ct er g enera t or d a ta.
R S - 232C in t e rf ace s p e c i f i c ati o ns
Sel ect ion b e t w een t w o si gnal s (pi n 6 (DSR) or pi n 25 (INI T)) i s possi b l e.
TM200 Co ntrol Circuit
Ther ma l he ad d r ive r cir c uit
T he pr int head of t he r eceip t p r i n te r mechan i sm is a ther mal typ e pr in t hea d wi th 576
d
o t s per li n e . A l l p r i nt h e a d c o nt r o l is p e rfo r m e d vi a a g a te a rr a y . A dr iv e r is b u ilt in t o
t h e pr in t he a d , an d send ing of p r i n t si gnal DATA-IN, wh ich i s sync hroni z ed wit h t he
CLOCK
sign al, to t he d r i v er sets t he pr int / non-p r i n t st atu s of each d o t . Da ta is
co
nf i r med by l a tch sig n al #LATCH . Pr int t i me con tro l is p e rfo r m e d b y # STROBE 1 a n d
#
STROBE 2, w h il e e n e r g i z i n g ti m e is c o n t r o lle d by th e ga t e a r ra y .
Changes i n head te m p erat ur e cau s e s f l uctuat io n of t he resistan ce v a lu e of th e
ther
mist or bui l t i nto t he hea d, whi ch i s o u tp ut as temperature sig n al THERMISTOR .
Pap e r f e ed m o to r dr iver c i rc uit
T he pa per feed mot o r is co nstant -current d riv en by a speci al - p ur pose I C. Th e
ener
giz i ng d i r ecti o n swi t c h ing sig n als (PH1,PH2,PH3 and PH 4) fr om the CPU . T he
spec
ial - pur p o s e IC c o n t r o ls th e p a pe r f ee d m o to r i n ac c o rd a n ce w i th th e s e si gn a l s
u s i n g Q 1, Q 2 , Q 3 , an d Q 4 s i gnal s .
A ut o c ut te r drive r c i rcuit
T he auto c ut ter d r i v e r use MOSFET to control DC motor .
De tec to r ci r c ui ts
Pa per e n d se nsor ci rcu i t
T he the r mal pr int e r mecha nism i s equi pped wi th a pap e r end senso r , whi ch i s
conne
cted v i a swi t ch cir c ui t boar d a ssem b l y to the m a in c i r c uit boar d u n it . The pap e r
en
d sign al FP_Sensor i s i n put t o th e DSP’s p o rt .
C o ver ope n se nsor c i rc ui t