LCD monochrome only need voltage regulator ON, OFF course and intensity which means only need 3 voltage conditions, i.e. the voltage ON, OFF and COMmon (brightness), such as on the LCD calculators (often also found type LCD without VCOM). While on a color LCD, many types of voltage is needed. To understand the voltages in LCD color, we recommend that you first reviewed the terms frequently encountered/voltage used. Among other things:
- VCC supply voltage is Colector, his opponent is a VEE. C and E stands for Colector and Emitter which means active components on the circuit of the Transistor is a disupply/igbt. While the supply voltage is VDD Drain, his opponent is VSS. D and S stands for Drain and Source which means the active components in a series of disupply is FET/MOSFET.
- GND is neutral, not VEE or VSS, although often encountered VEE or VSS GND in one line strung. An example is on the set of OCL amplifier, the output is the emitter, is supply each at the collector of the transistor. So this supply could be called input VCC + VCC-, medium and neutral is the GND/0.
- VREF is the reference voltage, this voltage is used to reference the regulation/settings.
- AVDD is Analog supply voltage, DVDD is the supply voltage while the digital. So too with the term and SEMESTER DATES DVCC. The difference is in the active component.
- HVDD voltage supply is for the IC column and row drivers (when worn).
- VGH is positive/high gate voltage (Voltage of the High Gate), whereas VGL was the negative/low gate voltage (Voltage of the Low Gate). While the GATE is the name of one of the legs of FETs/MOSFETs, it means that supplyed by the VGH and VGL have component active-type FETS/MOSFETs.
- VCOM Voltage stands for Common or shared voltage. At the beginning it has been mentioned that there are thousands even millions of active components in the LCD screen, the active component of this joint called VCOM voltage.
- VGAMMA Voltage is gamma. Often abbreviated as VGMA or VGM.
All Voltage to supply panels most of the supplyed of the DC to DC converter regulators, some small supplyed with regulator LDO. Description of the LDO is on this blog as well. Power supply panel area often encountered into one circuit TCON. This power supply input voltage 1 generally use only (PVDD) that supplyed of the mainboard or the PSU, then voltage is converted into a voltage for consumption among other panel voltage VREF, VCOM, VGH, VGL, AVDD, HVDD and VDDC.
The following is an example of IC and schematic power supply ic panel using CM501 and TPS65161.
In the schema, the input voltage panel of mainboard/psu is 12V. On some types of layer/panels use 3V3 and 5V input voltage. following each major voltage measured on the basis of standard panels (not closing the possibility of voltage can be different, depending on the manufacturer/type of panel):
- AVDD COF ic supply voltage, i.e. the COF panel, about 15V.
- HVDD COF ic supply voltage, i.e. the COF panel, about 8v.
- DVDD or VDDC voltage supply ic, namely the COF panel and TCON/controller ic, with about 3,3v, there are also supply TCON wearing 1,2v.
- VGL or VOFF, i.e. the voltage gate OFF, usually around -6V5 (minus 6V5). This regulation results from voltage voltage VGL initially around -12V.
- VGH or VON, i.e. the voltage gate ON, depending on the size of the inch/large panel, at 32in about 27V, the larger the size of the screen then the greater the VGH voltage as well.
- VGHM is the VGH voltage managed voltage, meaning here censored/protected and can be-on/off.
- VCOM voltage is common, this voltage as a reference about 28V, because VCOM is large, then the brightness control voltage VCOM can vary. There is also a large voltage is fixed.
- VREF is the reference voltage for the reference of the regulator/converter.
Generally, the ic power supply panel equipped with pin control, among others protection OVP and OCP, on/off, power good and input voltage detector. Here are some examples of pin power supply control panel:
- OVP is more voltage protection on outputs, when detected, then the ic will be OFF.
- OCP is overload protection, e.g. output short or overloaded, then the ic will be OFF.
- Power good signal/output voltage is that tells/sign that ic work well.
- On/OFF is the power control ic, so ic can be controlled from the outside, for example from ic TCON.
- Input voltage detector (I VDET), will detect whether or not enough voltage input.
More about the workings of the DC to DC can be learned in an article about power supply and about regulators.
VGH and VGL
A little offensive about VGH and VGL, why high voltage, VGH VGL are even below 0 (a minus). The reason/purpose is:
- The LCD cell is a capacitor dicharge and discharge by active components FET/TR.
- The nature of the capacitor is storing a voltage. When the capacitor voltage is filled and then removed then the voltage in the capacitor will gradually decrease until the missing/empty charge.
- VGH is made to charge capacitors (through the gate) along with the signal on/off of the column driver, consequently cells/capacitor is fully charged, so that the dead cells. If the gate/VGH removed, then the flame will gradually light. Or it could be said to leave a trace, because this is the nature of capacitors.
- In order not to leave traces, the capacitor must be didischarge/emptied quickly. The most practical way is to fill the transistor with reverse voltage (reversed polarity), i.e. with VGL.
- Because the active components in the form of 1 FET/TR, then the same with the polarity Inverter circuit, meaning that when the gate ON then the cells will die, when the gate OFF then it will turn on.
Voltage Common (VCOM)
VCOM voltage are used together in all components of the active cell in the matrix of the supplying distance Source (Emitter on TFT), medium Drain (collector) in the supply by the column drivers (COF) so that the voltage level/large VCOM can be used to set the brightness of the LCD picture.
When disorder VCOM, then brightening of the image can be changed. In general lines VCOM insert each COF column drivers, then allow the dark image in part (e.g., the existence of the line VCOM on COF the problematic because of corrosion or cracking).
When troubled VCOM at the base (in the section VCOM voltage source), it means there will be a disruption of brightness at full screen but not blank (because there is a small leakage of VGL on screen).
==
تم النشر يوم
السبت، 19 أغسطس 2017 ' الساعة
ليست هناك تعليقات:
إرسال تعليق