Golden View Display wants you to make an informed choice among our LCD products. The tech center provides you with most of the information you will need to understand liquid crystal displays.
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 |
|
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.