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Troubleshooting

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Troubleshooting

Troubleshooting

In this chapter, we provide our customer with a tool to troubleshoot during the sample stage. I would hereby emphasize this is very important to shorten the delivering time of our customer’s sample to the market. 

As we all know, your approval of our sample is prerequisite for your product to be delivered to the market, but in many case, a bad communication between the two sides takes a lot of time. To be specific, an inaccurate description of the problem leads to such an undesireable situation, actually, the problem is simple as picking up an object under your feet. In this sense, we strongly recommend you read this article carefully, because which is most helpful to realize our philosophy: shorten the time to the market.

We hope a quick approval of our sample as well as your sample by your customer with the help of this paper. So we list below most problems you will meet in the sample stage, based on our past experience.
Problems Phenomenon Potential reasons Solutions
Lower 
contrast 		The characters
are hazy in 
the range of 
promised view 
cone.
1)The operation voltage is
lower than the desired one.
2)The Vth of LCD is higher than the desired one.
3)The steepness (V90/V10)
is higher than the desired one.
4)The retardation of LC 
layer is not suitable.
5)The driving method 
doesn’t match the LCD.
1)Increase the 
operation voltage.
2)Decrease the 
Vth of LCD.
3)Decrease the 
steepness of LCD.
4)Adjust the 
retardation of LCD.

5)Adjust the bias circuit or driving 
frequency.

Ghosting 
(cross-talk) 		The off-segments 
are visible in the 
range of promised 
view cone
1)The operation voltage is 
too higher.
2)The Vth of LCD is too 
lower.
3)The steepness of LCD
is too higher.
4)The view cone of LCD
is too smaller.
5)The LC is 
contaminated.
6)The driving doesn't 
match the LCD.
1)Decrease the 
operation voltage.
2)Increase the 
Vth of LCD.
3)Decrease the 
steepness of LCD.
4)Enlarge the view 
cone of LCD.
5)More strict control on LC and LC filling 
process.
6)Adjust the driving
circuit.
 
Uneven
contrast 		The displayed 
characters are 
uneven.
1)The LC is contaminated.

2)The alignment layer of 
LCD has some problem.
3)The dopant content 
isn't suitable.
4)The driving frequency 
is too higher.
5)The contacting- resistance
of the according segments
is too higher.
1)More strict control on LC and LC filling
process.
2)The more strict 
control on PI curing,
and rubbing process.
3)Adjust the dopant 
content.
4)Decrease the 
driving frequency.
5) Improve the 
connections of 
electrodes.
Flicker The displayed 
characters or 
pictures are 
flickering
1)The driving frequency 
is too  low
2)The response time 
is too fast of LCD.
1)Increase the 
driving frequency.
2)Increase the 
response time.
Over 
power 		The power 
consumption 
is too high.
1)The driving voltage is
too high.
2)The driving frequency
is too high.
3)The capacitance of 
LCD is too high.
4)The ion content is too
high in the LC.
5)There are shorts between
some electrodes.
1)Decrease the 
driving voltage.
2)Decrease the 
driving frequency.
3)Decrease the 
capacitance of LCD.
4)Decrease the ion
content in LCD.
5)Check the electrodes to find
out what happened.
Small 
view 
cone 		The character 
can’t be seen
clearly when 
beyond some 
angle
1)The retardation of LC 
isn't suitable.
2)The steepness is 
too high.
3)The driving circuit 
settings isn't perfect.
1)Adjust the 
Retardation of LC
layer.
2)Increase the 
twist angle of 
LC layer.
3)Optimize the 
driving circuit 
settings.
The 
background
of LCD isn't 
desirable 		The color of 
LCD is different
with the desired
one.
1)The polarizer property
isn't the desired one.
2)The ITO glass isn't 
suitable.
3)The PI property and 
thickness isn't suitable.
4)The △n of LC isn't 
suitable.
1)Change to the
suitable polarizer.
2)Change to the 
suitable ITO glass.
3)Change to the 
suitable PI film.
4)Select the 
suitable △n  of  LC. 
Too strong 
parallax 		The color changes
too much when
side-view the 
LCD in off-state
1)The d of LCD cell
is too big.
2)The polarizer setting 
isn't suitable.
1)Decrease the 
cell gap of LCD.
2)Adjust the 
polarizer setting.
Trailing There is trail 
when displaying
a moving picture.
1)Too slowly switch 
off of LCD.
2)Too high driving 
voltage.
1)Decrease the 
cell gap.
2)Decrease the 
twist angle.
3)Decrease the 
driving voltage.
Narrow 
operation 
temperature 		The LCD can't 
normally operate 
at higher or lower
temperature.
1)The temperature 
coefficient of LC is 
too big.
2)The steepness is
too big of LCD.
3)The driving circuit 
setting unreasonable.
1)Select a LC with
smaller temperature
coefficient.
2)Decrease the 
steepness of 
LC layer.
3)Add temperature-
compensation circuit
if necessary.
Cold 
bubble 		The LCD appear
bubbles in a cold
circumstance 		1) Higher tension or
less flexibility with
the LCD cell. 		1) Optimize the
cell-making process
of LCD.
Imagine 
retention 		The undesired 
off-segment or 
parts displayed 
when the LCD 
addressed for 
a long time.
1)There is DC component
in the driving signals.
2)There are too many ions
in the LC.
1)Decrease the DC component in the
driving signals.
2)More strict control on the LC and LC 
filling process.
3)Select the PI with less polar-groups.
Lower 
Resistance 
to Electrical-
Magnetic 
interference. 		The LCD is 
susceptible 
to the electrical-
magnetic field. 		There is no electrical- magnetic shield in 
the application circuits. 		Add the grounded
circuits.
Lower 
resistance 
to the 
outside force. 		The displayed 
character would
move when a 
outside force 
applied. 		Too flexible of the
LCD structure. 		1) Add the spacer density and pressing after filling process.
Remark: The harder the LCD cell, the narrower the range of LCD storage and operation temperature range. That is the trade-off.



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