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UNDERSTANDING THE PANEL / SCREEN LIQUID CRYSTAL DISPLAY (LCD)

Understand Matrix preemptively (LCD, Plasma and Running Text)

Matrix is ​​the arrangement of pixels / dots that make up the LCD screen. A row of LEDs which is almost as running text viewer with LED lights which are also arranged to form a matrix. Examples of running text LED display 6x6 size, it means that in total there are 36 led (6 columns multiplied by 6 rows). Each LED is connected in a matrix by column and row. In the picture, which was given the green color is a column, while the other was given a yellow line.

Matrix can also be found in a series of keyboard keys, the aim is to summarize the number of cables. Examples like in the picture below (is the series of remote control, from the datasheet HT6221), consisting of 4 rows x 8 columns, a total of 32 buttons. You can imagine when one by one the buttons are separate cable, there will be 32 separate cables and this makes it very ineffective (whereas in the figure is only 4 + 8 wires only). In this matrix keyboard, the IC will scan / search buttons are pressed by reading the conditions of the column / row. For example, the IC will select row 1, and then read the column, if no reply is pressed, the IC will shift to the second row, and then read the column, if no reply is pressed, the IC will select rows 3 and so on. If no key is squashed, it must know the keys / pixels which are squeezed by noting "coordinate" her.

Even DOT-MATRIX printer such as EPSON LX-300 + also works based on the matrix consisting of a 9 pin / dot vertical.So technically LCD, LED matrix and matrix keyboard is the same. the key word is the number of pixels / button / dot, columns, rows, and how scanningnya. 
The LCD display is a collection of dots (dots) liquid crystal which forms the matrix of a certain size. Matrix composed of columns and rows, as in math on the matrix. If the analogy with a square, then let's just say the column is the width, while the line is long. While the first point of the elements called pixels. So if there is an LCD with a size of 320x240 pixels, meaning there are 320 dots width multiplied by the length of 240 points, a total of 76 800 dots / pixels. 
Since it is composed of columns and rows, the required control columns and rows. Often referred to as Row and Column Driver Driver. When the column driver problematic, of course, would appear to damage the image of a straight line up / down (in part or in whole). When damage to the row driver, it will show the damage to the line on the left / right (in part or in whole).

Memory also consists Area Structure Matrix

Memory (flash, eeprom, ram, etc), also using the matrix in it. Take for example the datasheet 24C01 eeprom memory capacity of 128 bytes (1 byte = 8 bits) so the total to 8 columns x 128 lines for a total of 1024 bits / point. 8x128 matrix is ​​linked to the Address Decoder (address translator) and Buffer of data, so the memory can be directly accessed the read / write memory contents at a particular address. As well as on the LCD screen, the data received by the t-con will be translated into data column and row, eventually can be displayed. On the panel / LCD screen, the system just writing alone, there should be no readings. Unlike the type of RAM memory that can read and write.

Liquid Crystal Cell (liquid crystal cell)

Unlike LED, incandescent or fluorescent, liquid crystal can not produce their own light. Liquid crystal is a type of crystal / glass rectangle that is mixed with oil and the crystals are nested / stacked.Because of the size of the crystals so small added more oil, then by naked eye closer to the liquid. Physically as the sand is solid, but if the sand is mixed with water, it will be called liquid sand. 
On the LCD monochrome (one color) as in the old calculator screen, the crystals are just open and close the cell. While polariser will feature updates (dark / light) so it appears the effects of light / flame (from external light reflected by the back layer of the LCD. Because the crystals formed have a corner (square box), then the crystal has a polar / polar. To understand how the polar LCD is as follows (does not need to be practiced in the absence of material, quite conceivable only):

1. Take a clear glass with a size of 3x9 cm square with glass thickness of 1 cm.
2. Stand glass with side 3 cm as the base, at eye level.
3. Put a flashlight with widths / large headlights less than 1cm behind the glass, turn on the flashlight. Then easily flashlight will break through the glass.
4. Then turn the glass by turning the glass a little to the left / right, observe light flashlight through the glass. The headlights will follow the direction of the slope of the glass and not more straight forward.
5. Then turn the glass up to the eye straight / flashlight. Then the flashlight will be restrained by the thickness of the glass, translucent hard.

Contained in the LCD cell is like a glass on top, a few pieces of crystal rods are stacked with a very small size that can be rotated electrically, so that the light from the backlight (back light) can be set in intensity and angle, total translucent or closed. When the cells LCD turned on, then the light backlight will be translucent total, when the die / off then it will shut down the light background, and this happens in cells / dot LCD. 
Because cell LCD is composed of liquid and crystal, then electrically These cells act as capacitors, has the ability to keep the voltage. As well as regular capacitors that require the process of charging / discharging and charging / discharging cargo. 
Examples of symbolic image pixel matrix LCD cells (from an outside source):

Active Components LCD Cells

The above-mentioned that the crystal must be arranged angular, twisted around by electrical conditions. The active components in the form of transistors or FETs. To move one cell / pixel means need one set transistor / fet for filling and emptying the cargo in the LCD cell. Often referred to as TFT (Thin Flat Transistor) because the glass LCD screen consists of a matrix arrangement of very thin transistor for each cell. For example LCD with a size of 320x240 pixels, meaning there are 76 800 sets of tiny transistors and thin embedded in the screen / glass. 
Excess than FET transistor is its resilience. The transistors have a low input impedance so it is not easily disturbed signals wild, but it took a great power (wasteful), so the track should be wide. Another shortcoming is the frequency of the switching transistor is low and poor linearity. So that the driving transistor LCD with fewer producing color, as well as a narrow angle it looks like on the screen / panel old types.Because using the path and a fairly large size, display / TFT panel becomes tend to be more durable. While based FET, more color, high speed, but the high-impedance so easily distracted and of course the track is smaller because more power efficient than the transistor-based. 
Figure movers cells and block cell / pixel LCD, the picture wearing a type FET and note the relationship column / row.(image from another source)

P0.0, P1.0, P1.1 and so is pixel / cell.Medium C-LC and C-ST in the picture is liquidnya (or the crystal liquid) which form a capacitor. VCOM and FET / TR will actively and mendischarge charging the capacitor. 
The voltage VCOM (Source) is a DC, being Drain voltage of the column driver is DC temodulasi digital (pulse) at high speed depending on the image that would be displayed.

The photo above is the LCD TV panel with a broken condition, the total thickness of the glass panels of less than 3 mm, is quite risky and easily broken / cracked. Inside the panel there is a smooth track and these pathways are not as flexible as the cable in open space.

Polariser and Gamma

As has been alluded to and practiced the above, the crystal is glass that will continue when the rays right angle. These crystals are rotated / controlled in accordance with the drawings, when the black color means the crystals in a position at the side (not transparent), the inclination or the degree of rotation of these crystals is regulated by gamma-degree rotation these crystals called polarity / poles. 
Polariser is a layer consisting of several layers the colors are arranged to collide with the slope of each color is different from a certain angle. For example there is a polariser layer with 3 colors red, green and blue. Polariser are organized in the order of red color at an angle of 45 degrees, green at an angle of 90 degrees and blue at an angle of 135 degrees.When the crystals in the LCD cell tilted 45 degrees, then the lights are passed will fall squarely on the polariser red color so it appears the red dot on the front of the screen / panel. When crystals tilted 90 degrees then the light will fall on the layer of green so green appear on the screen, and so on. When the light is forwarded incorrect or turn, then there is a rainbow of colors, for displaying multiple colors at once. 
Or another example of technology polariser is a picture of children's toys which, when viewed from the front display cat, when viewed from a 45-degree left turn into pictures of tigers and 45 degrees when viewed from the right side of the picture of a lion. 
the setting angle of rotation crystals in LCD regulated by gamma ie a voltage berjangkah stages from small to a certain size (degrees greyscale). Degree rotation regulated by gamma crystals. The more the number of voltage gammanya the resulting color will be. 
Because gamma plays an important role in generating the number of colors, then the damage can be predicted gamma clear, namely color defects. Work gamma governed by the color data from timing control (T-CON), so if the format of the color is not right, it is also inaccurate gamma producing color. 
On some products, the gamma reference voltage can be programmed or stored.Use to set White Balance, such as white balance settings on a CRT TV.

The photo above is the damaged panel polariser layer (wrinkles). This damage is caused because the temperature is too high when operating or in storage. Solutions with a new replacement or take polariser polariser traces of the other panel is damaged. If no polariser at all, then the image is very faint or greyscale (black-white) even if from the front almost invisible.

Resolution / Image size LCD and Refresh Rate

Resolution LCD screen has a fixed size, it means the amount of data displayed is always the same. For example if the RGB panel with 1366x768 matrix size means there 1366x768 = 1,049,088 RGB point.When the transistor-based, meaning there is an active transistor number of the screen. When the FET-based means no active fet the number of screen / panel. 
With the amount of 1,049,088 pixels, means any period of the appearance of images, the screen will load / display the digital data of 1,049,088 bit RGB (in one period). Because of the size of the fixed screen and the size of the fixed data, the data size of the coordinates of the screen is stored in the firmware, if the change or do not match, then the image will appear smaller or fragmented (due to the size of the image data is larger than the screen size). 
Technically in the process of LCD TVs, the image data captured by antenna / other sources, its size will be resized (adjusted) in advance to screen size before the data is sent across the screen.When the original image size is smaller than the screen, the zoom and larger when it is minimized. Pemrosesnya block called a scaler. Scaler and CPU needs RAM to this process. 
The refresh rate is the number of times the screen is removed and drawn again in a second. This speed depends on the quality of the screen and the picture quality to be displayed. The faster the refresh rate, the more did not blink. But rather wasteful power. In the PAL system, put on a 50Hz refresh rate, which means that every second image is deleted and drawn 25 times.

The photo above is the type of damage caused by the incompatibility between the data panel panel data set in the firmware with the size or specification panel. Images look truncated and not exactly one full screen.

Digital Viewer system (TV LCD, Plasma) and Scaler

Overview of technology viewer analog (TV / monitor CRT). Tube or CRT color / RGB only has three cathodes (R, G, B). This is a function cathode electron gun or call it the tip of a pencil that has 3 colors. While the front of the CRT is the canvas / paper drawing. Yoke (deflection yoke) is hand painted (for yoke serves as pembelok electrons). Meaning if no yoke / hand, the tip of a pencil will be silent amid the canvas so that only painted one point rgb alone. 
In the video system PAL format, speed painting is 25 fps (frames-per-second, which is a canvas full of painted within a trillionth of two five seconds or canvas is removed and then painted back as much 25kali every second. Early or movement pelukisannya can be progressive or interlace. Take the easiest, which starts from the top row of the left side, then pencil the way to the right (moving column) up until the very end, then pencil slide to the second row down from the leftmost column and then the road to the right until the end and so on. When you come to the last row and the last column, the canvas will be replaced by new (blank) along with the migration tip of a pencil into the top line column / most point of the left and so on until get 25 pictures per second [PAL format]. 
in the description above, the yoke will shift and paint horizontally and vertically, and therefore horizontal and vertical output amplifier is used to control yoke.When proper synchronization, the yoke will paint pictures correctly (precise coordinates, because the movement of the yoke according to the source image, synchronized). 
On TV Projector, technically the same as the CRT, the difference is the use of a CRT to a single color. When RGB, then took 3 separate CRTs. Rays coming out of the three CRT is mixed at the reflector (or the front of the screen). TV projector is the solution to CRT big screen up to 100 inches, because it is not very effective when there CRT RGB intact in a size of 100 inches. 
Depiction image on a CRT does not require digital data, pure analog controlled by the synchronization signal and chrominance / color in the signal video to be displayed. Remember, CVBS is a composite video signal, meaning the video signal is present H + V synchronization signal and the signal color (chroma). Or when observing jack input of the monitor will consist of signals R, G, B, H and V (when five of these signals are combined into one, then it could be a signal CVBS). 
While the System Viewer Digital (as that applied in LCD TVs and Plasma ), is very much different from the analog system.That happened in the renderer process digital images are summarily as follows:

1. All analog signals will be processed first translated into digital data (ADC, analog to digital). Analog signal for example video and audio, or even IF output signal of the tuner.For example here is the image signal / video for which will be reviewed here on digital video viewer system.
2. CPU will take a sample and check the format and measure how the resolution / size of the images contained in the digital data ADC result. For example readable format is PAL 25fps, means the CPU will take one picture / frame (or image / data along seperdualima second).Because the PAL format, it is known that the image size is 720 x 576 (720 columns x 576 lines).
3. Then CPU will adjust size (resize) image data taken earlier to match the screen size / panel. Tool / part size regulator is called scaler. So, for example, the panel LCD / Plasma Spoken size of 1366x768 pixels, then the CPU will command section Scaler to resize an image of 720x576 pixels into 1366x768 pixels (so do not be surprised if some say the picture so it looks short and fat) ,
4. Once the image data is completed resize, then the image data that are appropriate to the size of the screen / panel are then sent to the panel / screen to be displayed.
5. Processes 1 to 4 above, in PAL format, done within seperdualima seconds to 1 frame / images, so that in one second can process as many as 25 pictures / frames. Due to the above already explained that one pixel is equal to 1 bit, then the screen / panel will receive data at 1366x768 bit as much as 25 times per second. Which when totaled to around 25Mbps (25 megabitper-second), 25fps for PAL format.

Frames-per-second is a roll of film theaters that screened and highlighted by a lamp and the light that passes through the film was dropped onto the screen. 1 images in the film roll is 1 frame, was for a duration of 1 second is composed of 25 images, "which looks" at all. There also are 30 images / sec or another frame rate, for example, to record a grenade explosion required speed camera to record up to 300 fps (300 frames-per-second), meaning that events could terrekam sepertigaratus seconds.

Timing Control (T-CON)

In general, the output data of the mainboard TV / LCD Monitor has a level LVDS (Low-voltage Differential Signalling) with serial data. Said differential means pairing between data Plus and Minus.LVDS technology makes it possible to transmit high-speed data transfer. As more and more pair / pairs then transfer speed will be faster. Several types of configuration LVDS cable on LCD TVs, among others:

1. 6-bit Single Channel, consists of 1 pair cable 3 pairs Clock and Data Cable (ClkP, ClkN, Rx0P, Rx0N, Rx1P, Rx1N, Rx2P, Rx2N).
2. 6-bit Dual Channel, consisting of one pair of wires Clock is even, one pair of wires Clock odd, three pairs of data cables even, three pairs of data cables odd (OClkP, OClkN, ORx0P, ORx0N, ORx1P, ORx1N, ORx2P, ORx2N, EClkP, EClkN , ERx0P, ERx0N, ERx1P, ERx1N, ERx2P, ERx2N).
3. 8-bit Single Channel, consisting of one pair of wires CLK and 4 pairs of wires Data (ClkP, ClkN, Rx0P, Rx0N, Rx1P, Rx1N, Rx2P, Rx2N, Rx3P, Rx3N).
4. 8-bit Dual Channel, consists of 1 pair Clock is even, 1 pair Clock odd, four pairs of data is even, and 4 pairs of data is odd (OClkP, OClkN, ORx0P, ORx0N, ORx1P, ORx1N, ORx2P, ORx2N, ORx3P, ORx3N, EClkP, EClkN , ERx0P, ERx0N, ERx1P, ERx1N, ERx2P, ERx2N, ERx3P, ERx3N).
5. 10-bit Single Channel.
6. 10-bit Dual Channel. And others.

O and E above abbreviation of Odd and Even (odd and even). LVDS technology is the development of a LAN cable that consists of four wires that TXP (green and white), TXN (green), RXP (blue and white) and rxn (blue) are arranged in pairs (twisted one pair consists of two wires).With such arrangement, the transfer speed of 100Mbps LAN reached quite easily realized if the exposed wire with a diameter of 0.5 mm were twisted by certain rules (ma'af not the author discussed here about the advantages of cord twisted). 
While the data format sent from the mainboard / controller TV / LCD Monitor is Normal LVDS and JEIDA. In TCON, often found the facility to change the format of the data reception, JEIDA Normal or LVDS (see datasheet panel / screen for more details). 
Function TCON is receiving image data and then translate the results of the CPU in the form of digital RGB image data sent via LVDS. Digital RGB image data is then translated into a pixel data comprising:

1. Data row (ROW) and data column (COLUMN) RGB (LVDATA-RGB).
2. Signals / pulses synchronization control consisting of STV (vertical / blanking / erase), OE (output enable), CPV (clock) and others.Data synchronization is made to control the driver ic ic-panel / screen so images can be shown / painted properly.
3. Color data in reference tables list greyscale (which is generally stored in eeprom), the result is a Gamma voltage.
4. Other control signals, such as power supply control panel, blanking, test patern and others.

To be able to work, TCON must have a clock. Most TCON use of LVDS clock, there also has its own clock generator.TCON also uses RAM to buffer data when the decoding process. Damage RAM on TCON cause interference signals generated by TCON TCON work even failure itself (hang).

Photos of some form of physical blocks Timing Control (T-CON)

Because the TCON is "drafts" or the controller clock / time, then it must be with speed and accuracy is quite high. If there are data errors or translation errors (decoding), the picture may not appear or appear deformed, speckled randomized, split, color defects, no precise coordinates of the pixel and others. 
In sum, TCON generates the signals necessary to display an image to the matrix at the same driver / controller matrix. TCON block is generally equipped with a power supply circuit that provides DC to DC supply voltage for the panel and TCON itself (the discussion of this power supply in other parts). 
Data line is the data transferred to the row driver or often referred to as a gate driver. While the column data is data that is sent to the column driver or often referred to as a data driver. Data column in the form of RGB data which terdekode data greyscale / gamma so the LCD can display color images. Greyscale is a reference color scale consisting of colors from white to black is divided into several steps / step. A gamma voltage, representing a greyscale color scale. As an illustration, the color produced by black and white CRT is greyscale.

The photo above is a damage to the LCD on the block TCON, data and signals from the T-CON impaired, so that the folded picture (slide) due to loss of synchronization, as well as the color of damaged / not normal.

Panel Regular / Conventional (Row / Column Gate Driver and Driver)

Conventional LCD viewer consists of a liquid crystal matrix panel, row driver (often referred to ear, because the shape of COF or embedded) and column driver (often mistakenly called COF). Matrix / LCD cell area in the picture illustrated by color pink / magenta. Row driver produces a signal ON / OFF for each line matrix (signal Gate ON / OFF). While the column driver generates a signal / color for each column of the matrix. Here is a simple chart of conventional panel:

Row driver in the form of IC (chip-on film, COF) that is located next to the matrix and the output is connected directly with each row of the matrix (with GATE fet foot drive in the crystal matrix). While the column driver also in the form of IC (chip-on film, COF) located on the top / bottom of the matrix and the output is connected directly to each column of the matrix (foot Source fet driver of crystals in the matrix).
Data column of TCON sent to the column driver cascade to the column matrix driver more than 1. in its technical, TCON will fill the first driver column of data, when it is full then the first driver column of data will tell the next driver through COL_FLAG_OUT column and so on until all the column drivers terset / filled. 
Data line of TCON sent to the row / gate driver in cascade to the matrix with row driver more than 1. in its technical, TCON will fill the first driver row of data, when it is full then the first row driver will tell the next driver through ROW_FLAG_OUT row and so on until all the row driver terset / filled. 
for LVDATA required transmission signal and the signal CLOCK STATUS / control.The data is sent to a serial or parallel. In the LCD panel controller, is often found in the form of RGB LVDATA parallel to the column. While the data lines often found in serial form (due to the location of the row drivers are on the side of the matrix so that the area is very limited). Serial data transmission requires CLOCK signal (CKV), SET / RST / STV, OE, and DATA.Sometimes the data is amalgamated with the signal CKV. Row in the matrix are arranged vertically, meaning that if all row drivers are fully charged, then the data will be deleted, and then filled again from the first row again and so on. One-time data entry period all these lines are often called STV time or start Vertical (one period of the pulse STV). 
Large gate voltage is close to or the same as when the OFF condition VGL and VGH close to or the same as when the condition ON. So the row driver requires a voltage VGH / VON and VGL / Voff to move the gate. Therefore, the voltage VGL and VGH inserted directly into Row Driver,
VCOM voltage or supply voltage source together is a matrix. VCOM voltage is DC.This voltage is inserted directly into the matrix via the column driver. Because this voltage used together in a group matrix, the brightness can be tuned by adjusting the voltage large matrices. 
To facilitate the grouping of cells, the number of the cell area divided by the number of COF attached. Eg a panel with 4 COF column driver, means that the column of the screen is divided into 4 sections. So if there is one COF is not working (broken / dead) then it will be a quarter of the column blank screen.Likewise with COF row / gate driver.

Panel type in-Plane

When compared to conventional panel types above, there are clear differences in the configuration row driver (or gate driver). Disadvantages of conventional panels, is using ICs COF to row drivers that could lead to the failure of contacts, easy to corrosion and more work. This deficiency in terms of producers will increase production costs. To cover this, the producers make ic row so the driver directly on the panel and made simultaneously when the panel / matrix made (IC row / gate driver is made to stick and inside the glass panel). Because it is made into one screen, it is often referred to as in-plane technology.Coincided with this technology, also developed improved image quality by altering the shape of the cell so that the viewing angle lcd wider (made conical cells, the cells no longer flat as before).Here is a simple block diagram panel in-Plane (with one set CKV, CKVB only):

Inserting the VGH voltage directly to the IC row / gate driver is planted in the panel is very risky and have high failure, due to the size and specifications of IC is made ​​very small. To overcome this, they invented the system clock and the data of its own processing voltages VGH and VGL to be sent to the ic row / gate driver in panel. 
Block processor voltage VGH and VGL into data clock and data gate is called Gate Clock Generator, which generates a signal / pulse STVP (start vertical sync), CKV (clock), CKVB (clock bar or row of data) and VSS (minus, slightly larger than the VGL, about -7V5). Signals from these generators should really synchronized with the image to be displayed. 
IC which functions as a clock gate generator often seen separately from the power supply there is also the one with ic power supply panel for example BD8193 (panel brand Samsung). 
Because the level signal from the gate clock generator under voltage VON / Voff for normal cells, then made ​​IC row / gate driver flanking matrix, to the right and dikiri matrix. The goal was to make the cells can be perfect ON and OFF for parallel gate supplied from the right and left of the screen. 
It is often found in-Plane several panels that use more than one set of clock and data signals gate. For example wearing 3 pairs CKV & CKVB (CKV1, CKV2, CKV3, CKVB1, CKVB2, CKVB3). Clock and data on a single gate, each line / gate to get the drive of the first row ic / gate driver.While the three pairs of clock and data using three ic row gate / gate driver (mean 3 ic on the right, and 3 ic in the left panel). The first IC will mendrive gate / line 1, 4, 7, 10, 13, and so on. The second IC will mendrive lines 2, 5, 8, 11, 14, and so on. And third IC will mendrive lines 3, 6, 9, 12, 15, and so on. Working sixth gate driver IC is really to be synchronized.When the full screen is already envisaged, then the signal STVP will clear the screen and start drawing / new scanning. STVP voltage is approximately minus -11V pulse, it takes a high level because STVP also used to clear a full screen of each scanning period.

The photo above is the type of panel damage in-Plane, when one row ic / gate driver in panel damage a short-circuit, the data on the gate driver ic will be disrupted. Eg gate driver output quota to 10 filling lines will move fill / mendrive other line. A short-circuit between lines due to corrosion or due to moisture can also lead to disruption of the data output gate driver. There are 2 blocks ic gate driver on the right and left of the panel, it is possible only one gate driver IC are broken.

Supply voltages Screen / LCD panel

Monochrome LCD only requires a voltage regulator ON, OFF and intensity are meant only need three voltage conditions, ie voltage ON, OFF and COMMON (brightness), such as the LCD calculator (often also found types of LCDs without VCOM). While the color LCD, many types of voltage is needed. To understand the voltages in LCD color, preferably for reviews first voltage terms are often found / used. Among others:

1. VCC is the supply voltage Colector, the opposite is VEE. C and E stands Colector and emitter, which means the active components in the circuit is supplied is a transistor / IGBT.While VDD is the supply voltage Drain, his opponent is VSS. D and S stands Drain and Source which means that the active components in the circuit is supplied by FET / MOSFET.
2. GND is neutral and not VEE or VSS, although often encountered VEE or VSS is rolled into the GND lines. An example is the OCL amplifier circuit, the output is the emitter, while supply respectively at the collector transistor. So-called input can supplynya VCC- VCC + and, being neutral is GND / 0.
3. VREF is the reference voltage, this voltage is used for reference regulatory / settings.
4. Is AVDD Analog supply voltage, while DVDD is the digital supply voltage. Likewise with the terms AVCC and DVCC. The difference is in the active components.
5. HVDD is the supply voltage to the IC column driver and the row driver (when used).
6. VGH is a positive gate voltage / high (Voltage of Gate High), while VGL is a negative gate voltage / low (Low Voltage of Gate). While GATE is the name of one of the legs of the fet / mosfet, it means that supplied by VGH and VGL active berkomponen manifold FET / MOSFET.
7. Stands for Common Voltage VCOM voltage or shared. At the beginning we mentioned that there are thousands and even millions of active components in the LCD screen, the active component requires joint called VCOM voltage.
8. VGAMMA is a gamma voltage.Often referred to as VGMA or VGM.

Voltages to supply panels mostly supplied from a DC to DC converter regulator, patches supplied by the LDO regulator. Description of the LDO in this blog as well. Block power supply panel often found together with a circuit TCON.Power supply is commonly used input 1 voltage only (PVDD) is supplied from the mainboard or PSU, then the voltage is converted into a voltage to the consumption of the panel include voltage VREF, VCOM, VGH, VGL, AVDD, HVDD and VDDC. 
Here are examples of IC and scheme panel power supply using ic CM501 and TPS65161.

In the scheme, the input voltage panel of mainboard / psu is 12V. In some types of layer / panel there is a use 3V3 and 5V input voltage. The following were each large voltage is measured by the standard panel (not rule out the voltage could be different, depending on the manufacturer / type of panel) By Imran Ashraf

1. AVDD COF, COF ic ie supply voltage panel, approximately 15V.
2. HVDD COF, COF ic ie supply voltage panel, approximately 8V.
3. DVDD or VDDC, ie supply voltage and ic ic COF TCON panel / controller, around 3V3, there is also supply TCON taking 1V2.
4. VGL or Voff, the OFF gate voltage, typically around -6V5 (minus 6V5).This voltage regulation results from the first VGL voltages around 12V.
5. VGH or VON, the gate voltage ON, depending inch size / large panels, the 32in approximately 27V, the larger the screen size, the greater the voltage VGH.
6. VGHM is that termanaged VGH voltage, voltage means here censored / diprotek and can be on / off.
7. VCOM is a common voltage, this voltage as a reference about 8V, because VCOM is a brightness regulator, then great VCOM voltage can vary. There is also a large voltage is fixed.
8. VREF is the reference voltage to the reference regulator / converter.

In general, ic power supply panel is equipped with a pin-pin control, among others, OVP and OCP protection, on / off, power good and input voltage detector.Here are some examples of pin-pin power supply control panel:

1. OVP is overvoltage protection at the output, if detected, the ic will be OFF.
2. OCP is the overload protection, output short-circuit or overload eg load, the ic will be OFF.
3. Power good is the signal / output voltage that is to say / sign that ic works well.
4. ON / OFF is a power control ic, ic so it can be controlled from the outside, for example from ic TCON.
5. 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 the power supply and on the regulator.

VGH and VGL

Slightly offensive about VGH and VGL, why high voltage VGH, VGL was even below 0 (minus). The reason / purpose is:

1. LCD cell capacitor is charged and the active component didischarge by FET / TR.
2. The nature of the capacitor is storing a voltage. When the voltage of the capacitor is charged and then released it in a capacitor voltage will gradually decline to missing / empty cargo.
3. VGH is made to charge the capacitor (via gate) in conjunction with the signal on / off from the column driver, consequently cell / capacitor is fully charged, so that the cells die. When the gate / VGH is removed, then the flame will gradually light. Or it could be said to leave a trail, because this is the nature of the capacitor.
4. In order not to leave a mark, the capacitor must didischarge / emptied quickly. The most practical way is to fill the transistor with a reverse voltage (reverse polarity), by VGL.
5. Because the active component in the form of one FET / TR, the same as the polarity inverting circuit, meaning that when the gate ON then the cells will die, when the gate OFF will light up.

Common voltage (VCOM)

VCOM voltage is jointly used in all active components of the cell in the matrix that supply the legs Source (Emitter on TFT), is being Drain (collector) in supply by the column driver (COF) so that the level / large voltage VCOM can be used to adjust brightness LCD image. 
When VCOM interference, then the image brightness can be changed. In general lines VCOM inserted in each COF column driver, then allow the dark image portion (eg, the path VCOM on COF problematic because of corrosion or cracking). 
When VCOM troubled at the base (at the voltage source VCOM), meaning there will be interference brightness on a single screen but not blank (since there was a small leak in one of VGL screen).

The pictures Collection Examples Damage LCD Screen

Panel damaged COF not working, broken or "disappeared". Because of the lost / damaged one cof, then the image will be clipped on line COF damage only and precisely because ¼ display panel in the image above using the 4 COF column driver.

Panel damaged data across two drives (row / col gate driver and driver), can also be due to the row of clock driver lost TCON.

Thin vertical lines for the output of existing Column Driver is cut off, being visible image zoom can be due to disruption of the data TCON and frimware on the mainboard is not right.

Figure double, the explanation is over (at the panel discussion in-Plane).

COF Column Driver corrosion

The signaling pathway towards the row / gate driver inplane corrosion in the glass / panel.

Corrosion in the glass / panel (gate signal line driver)

RGB data (LVDATA) is disturbed.

RGB data (LVDATA) interrupted, are not synchronized.

Data path to the row / gate driver left midway panel.

Panel tompelen, crystal cells leak to the side (to other cells) so that the polarization can no longer be displayed.

VCOM voltage disorder that can be caused VCOM lines on COF problematic because of corrosion or cracking).

Voltage VGH or VGL less, there may be ngorupsi in the middle of the road.

Voltage VGH or VGL less, there may be ngorupsi in the middle of the road.

Pronounced thanks to friends of the author who has contributed photographs of damage to the LCD as a supporter of this article.

By Imran Ashraf 
lcdledebooks@gmail.com
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