Toshiba CN27E90 Technical Training Manual page 72

3-2. Drive System
3-2-1. ON drive system
When the drive transistor is on, the horizontal output transistor
also turns on.
Merit:
• The base current can be precisely controlled without
being affected by variation of pulse width which is
caused by the horizontal oscillator circuit and the drive
circuit.
Demerit:
• It is difficult to flow a reverse bias current to the horizontal
output transistor to eliminate its storage carrier for transient
period of on to off period for the horizontal output
transistor.
H driver
H OSC
ON
(OFF)
H output
ON
+B
(OFF)
Fig. 11-3
3-2-2. OFF drive system
When the drive transistor is on, the horizontal output transistor
is off.
Merit:
• Energy balance between on and off periods of the drive
circuit is better, and the circuit can be simplified.
• Reverse base current of the horizontal output transistor
can be controlled easily.
Demerit:
• Base-emitter forward current flowing into the horizontal
output transistor is susceptible to on-period variation of
the drive transistor.
H driver
H OSC
72
H output
ON
ON +B
(OFF)
(OFF)
Fig. 11-4