REV.-A
2.2.4 Main Switching Circuit
This circuit uses a ringing choke converter
AC input switching power circuit. This system has the
merits of using fewer parts and a smaller
and is often used when a smaller power supply is
required.
2.2.4.1 Circuit Operation
Figure 2-14 shows the main switching
When the power is applied, drive current flows to the base
of switching transistor
via starting resistor R14. Diodes D20, D21, D22 on the secondary side of TI
prevent current flow in the secondary side. Therefore, as shown in Figure 2-15, collector current from Q1
reaches the same level of current which flows in the coils, and starts from O [A] so that a small base
current can switch
on.
is turned on, the primary side of transformer coil
receives an input
voltage which induces voltages in windings 1-11-8 and T9-10 (represented by
and
respectively).
releases current in the direction which
the gate of the
(Refer to 2.2.3) to conduct, and
releases base current in the direction which causes
to remain on. The value of is constant as
shown in the following formula :
/
V
I N
+
(1 +
Therefore, when collector current increases as shown in Figure 2-16, the relationship between and DC
current amplification rate
can be expressed by the
x
=
where is fixed and
insufficient because of carrier saturation so
is turned off. As a result, the voltage at
and
drops and base current runs out, and QI is
switched off.
When QI is switched
off,
back electromotive force which has the opposite polarity from the previous
momentarily flows through the windings of the transformer. Since the amount of energy P [W] is equal to
that stored in the transformer before
is turned off, P is :
:
of
: Peak
Of
2-20
Summary of Contents for LQ-1060
Page 1: ...EPSON TERMINAL PRINTER L Q 8 6 0 1 0 6 0 TECHNICAL MANUAL ...
Page 5: ...REVISION TABLE REVISION DATE ISSUED I CHANGE DOCUMENT I I 1st issue I v ...
Page 68: ...cc o REV A N N n 1 cc b I al cc u co n4 2 1 Figure 2 14 Main Switching 2 21 ...
Page 79: ...REV A Table 2 20 State of Module 1 1 I W stay E H H L H d O s H H 4 2 32 ...
Page 203: ...Figure 5 6 MONPS MONPSE Board Voltage Waveforms 5 17 ...
Page 204: ...REV A Fiaure 5 6 MONPS MONPSE Board Voltage Waveforms z L 5 18 ...
Page 205: ...Figure 5 6 MONPS MONPSE Board Voltage Waveforms 5 19 ...
Page 248: ...REV A A 3 DRAWINGS 3 J32 J TI g 4 Figure A 27 MONPS Board Component Layout A 34 ...
Page 250: ... 2 1 1 1 1 I A b 2 Ozaz 1202 C O ZZH Z UOEE vu I 1 Figure A 29 MONPS Board Circuit Diagram ...
Page 252: ...L t g Figure A 31 JUNMM Board Component Layout A 38 ...