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5-4-2(B) FUNCTIONS OF PULSES
! Y rising ramp pulse
When an external voltage of about 390V~400V is applied on the Y electrode during the Y Rising Ramp
time and each gap voltage reaches the discharge sparkover voltage, a weak discharge begins. While
the weak discharge is maintained, negative wall charges are accumulated on the Y electrode and posi-
tive wall charges are accumulated on the X and address electrodes, respectively.
@ Y Fallimg ramp pulse
During Y rising ramp period, weak-discharge begins when external voltage of about 390V~400V is
impressed to Y electrode, and each gap voltage is equal to discharge start voltage. Sustaining the
weak-discharge, positive wall charge is accumulated in X electrode and address electrode, and nega-
tive wall charge is accumulated in Y electrode of the entire panel.
# Y Scan Pulse
Also referred to as Beam Pulse. Selects the Y electrodes line by line. During this process, the Vscan is
called Scan Bias Voltage. About 70V are applied to the electrode line to which Vscan voltage was
applied, and the 0V (GND) voltage is applied to the other electrodes. However, since all negative
charges are accumulated on the Y electrodes due to the application of ramp pulses and positive wall
charges are accumulated on the address electrodes, the cells to which address pulses (70V~75V)
are applied have more voltage than the discharge sparkover voltage and thus generate address dis-
charges. Since the beam pulse and the data pulse should be applied one line at a time, the PDP
address time is therefore very long.
$ 1st Sustain Pulse
The Sustain Pulse always starts from the Y electrode, because positive wall charges are formed on the
Y electrodes when an address discharge occurs. Since the wall charge formed by an address discharge
is usually less than the wall charge formed by a sustain discharge, the first discharges have a low
strength and are stabilized after 5~6 discharges, though it may differ depending on the structure of the
electrodes and the environmental conditions. Hence, the reason to maintain the first sustain-pulses for
a long time is to form a stabilized first discharge and generate as many wall charges as it possibly can.
Samsung Electronics
Circuit Operation Description
5-25
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