Knowledges about LCD

Q.	Why I can't see any data on the LCD?
A.	Please follow the spec; use a POT to adjust the VEE ( VO ) voltage to turn on the LCD.

Q.	How to turn on the 4.5 volt LCD with the 3-volt VDD?
A.	You need provide -1.5 volt to the VO. We recommend you to use a DC to DC voltage converter IC, such as SCI7661, HT7660 or equivalent if you don't have a -1.5 volt on your power system.

Q.	How to turn on the LED back light?
A.	Please check the spec with the LED forward voltage and current. Generally, one LED forward voltage is 2.05 V and current is 10 mA. For the 3-volt power system, there are many LED arranged in parallel. For the 5-volt power system, 2 LED arranged in a string, it forward voltage is 4.1 volt; current is 10 mA and many in parallel. Both LED back light, need current limit resistor either on our board or yours, for drop your system power to meet LED forward current spec.

Q.	How to turn on the EL panel back light?
A.	To turn on an EL panel, typically need about 100 Vrms @ 400 HZ and it current consumption is about 0.12 mA per CM square. The EL driver IC that we often use and recommend is IMP and SIPEX.

Q.	What is function of the M signal?
A.	AC signal for LCD driver output. Alternate signal input pin for LCD driving. Normal frame inversion signal is input in to this pin. If lacks the M signal, can create the liquid crystal the polarization, the demonstration effect unusual difference.

Q.	What is function of the /DISPOFF signal?
A.	Display off control. Control input pin to fix the driver output to V0 level, during "Low" value input. LCD becomes non-selected by V0 level output from every output of segment drivers and every output of common drivers. Protects LCD the liquid crystal in does not use the screen the time closure demonstration.

Q.	Why when CCFL back light LCM light, the picture demonstrates can have the water ripple? How eliminates?
A.	The water ripple occurs is the result of the LCD drive signal by the CCFL high voltage disturbs, bezel connect to GND may isolate the disturbance causes LCD to drive signal stable, elimination picture demonstration water ripple phenomenon.

Q.	When customer use LCM, must pay attention to these.
A.	1. Connection Cable must as far as possible short. 2. TFT module bezel have to connect to GND. 3. Mechanism design must pay attention TFT-LCD angle of view. 4. Opens CCFL the Inverter easiest to use entire system goes. 5. Avoids contacting the corrodent. 6. Avoids receiving the external force extrudes and hits. 7. LCD surface like has the dust must use the quite soft cloth gently to clean. 8. LCD surface adds the transparent protection piece, protects the piece must have the enough degree of hardness. 9. Attention use temperature and environment. 10. Avoids demonstrating identical picture excessively long 11.Response time and the temperature related.

Q.	Module with quality problem and need replacement.
A.	Please take a picture of defect phenomenon firstly and we shall provide technical support directly by seeing photo. If defect reason can not be judged by photo and please send it back to DI for replacement.

Q.	How to choose a CCFL INVERTER ?
A.	1. Inverter output current must be equal to CCFL lamp current. 2. Inverter output frequency must be equal to CCFL lamp frequency. 3. Inverter open lamp voltage must be higher than CCFL 0℃ startup voltage. 4. It would be best that there is a CCFL controller IC on inverter. 5. Inverter strike time must more than 1 second.