LQ121S1LG61 Просмотр технического описания (PDF) - Sharp Electronics
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LQ121S1LG61 Datasheet PDF : 20 Pages
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LD18123A-7
7-2. Backlight driving
The backlight system is an edge-lighting type with two CCFT (Cold Cathode Fluorescent Tube).
The characteristics of single lamp are shown in the following table.
Parameter
Symbol Min. Typ. Max. Unit
Remark
Lamp current range
IL
3.0
6.0
6.5 mArms [Note1]
Lamp power consumption PL
-
3.5
-
W [Note2]
Lamp frequency
FL
40
60
70 kHz [Note3]
Kick-off voltage
Vs
-
-
1300 Vrms
Inverter output
[Note4]
-
- (2000) Vrms Transformer output Ta=
at barast capacitor =12pF -30 oC
Lamp life time
LL 50000 -
-
hour IL=6.0 mArms
[Note5]
60000 -
-
hour IL=5.0 mArms
[Note5]
[Note1] Lamp current is measured with current meter for high frequency as shown below.
CN2,3：1pin
Inverter
Module
Ａ
CN2,3：2pin 〜
Inverter
Ｖ 〜 output voltage
Transformer
Ｖ
〜
output voltage
[Note2] Referential data per one CCFT by calculation. (I L × VL)
The data don’t include loss at inverter. ( IL=6.0mArms)
[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 voltage above this value should be applied to the lamp for more than 1 second to start-up.
Otherwise the lamp may not be turned on.
[Note5] Since lamp is consumables, the life time written above is referencial value and it is not guaranteed in
this specification sheet by SHARP.
Above value is applicable when lamp (the long side of LCD module) is placed horizontally.
(Landscape position)
Lamp life time is defined that it applied either ① or ② under this condition
(Continuous turning on at Ta=25 oC, IL=6.0mArms)
① Brightness becomes 50% of the original value under standard condition.
② Kick-off voltage at Ta=-30 oC exceeds maximum value,1300Vrms.
(Lamp lifetime may vary if lamp is in portrait position due to the change of mercury density inside the lamp.)
In case of operating under lower temp environment, the lamp exhaustion is accelerated and the brightness
becomes lower. (Continuous operating 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.
Be sure to use a back light power supply with the safety protection circuit such as the detection circuit
for the excess voltage, excess current and or electric discharge waveform.
Be sure to use the detect circuit by which one side of the CCFT lamps can be controlled independently.
Otherwise, when one side of the CCFT is open, the excess current may possibly be applied to the other
side of the lamp. Recommended inverter is “CXA-0454(TDK)”.
(“CXA-P1212B-WJL(TDK)” is also recommended under general temperature condition.)
[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.
[Note8] Under the environment of 10lx or less, miss-lighting or lighting delay may occur.
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