Programming instructions

LD-14304-6
6-2. Backlight driving
The backlight system is an edge-lighting type with twin CCFT (Cold Cathode Fluorescent Tube).
The characteristics of single lamp are shown in the following table.
Ta=25℃
Parameter Symbol Min. Typ. Max. Unit Remark
Lamp current
I
L
3.5 6.0 7.0 mArms
【Note1】
Lamp power consumption
P
L
－
2.8
－Ｗ 【Note2】
Lamp frequency
F
L
40 60 70 KHz
【Note3】
Kick-off voltage
Vs
－－
1000 Vrms
Ta=25℃
－－
1300 Vrms
Ta =0℃【Note4】
－－
1450 Vrms
Ta =-10℃
L
L
50000
－－
hour
【Note5】I
L
=6.0mA
Lamp life time
L
L
30000
－－
hour
【Note5】I
L=
7.0mA
【Note1】 Lamp current is measured with current meter for high frequency as shown below.
【Note2】 At the condition of Y
L
=350cd/m
2
【Note3】Lamp frequency may produce interference with horizontal synchronous frequency, and this may cause
beat on the display. Therefore lamp frequency shall be detached as much as possible from the horizontal
synchronous frequency and from the harmonics of horizontal synchronous to avoid interference.
【Note4】The open output voltage of the inverter shall be maintained for more than 1sec; otherwise the lamp
may not be turned on.
【Note5】Since lamp is consumables, the life time written above is referential value and it is not guaranteed in this
specification sheet by SHARP.
Lamp life time is defined that it applied either ① or ② under this condition.
(Continuous turning on at Ta=25℃, IL=6 or 7mArms)
① Brightness becomes 50% of the original value under standard condition.
② Kick-off voltage at Ta= -10℃ exceeds maximum value, 1450 Vrms.
In case of operating under lower temp environment, the lamp exhaustion is accelerated and the brightness
becomes lower.
(Continuous operating under for around 1 month under lower temp condition may reduce the brightness to
half of the original brightness.)
In case of such usage under lower temp environment, periodical lamp exchange is recommended.
【Note6】The performance of the backlight, for example life time or brightness, is much influenced by the
characteristics of the DC-AC inverter for the lamp. When you design or order the inverter, please make
sure that a poor lighting caused by the mismatch of the backlight and the inverter (miss-lighting, flicker,
etc.) never occur. when you confirm it, the module should be operated in the same condition as it is
installed in your instrument.
【
Note7
】
It is required to have the inverter designed so that to allow the impedance deviation of the two CCFT
lamps and the capacity deviation of barast capacitor.
Module
Inverter
Ａ
～
* 3
p
in is V
LOW
１
3
１
3
Ａ
～
05-Oct-2005