The popularity of LCD monitors developed rapidly inside the past 5 years. So you can the technology growth the actual planet notebook market has absorbed a number of desktop applications, in the form factor they provide, without taking into account the text of the copy desk is very clear and enormous format CRT display. Now, with the merging of personal computers and multimedia experience, the video reproduction is becoming a key requirement with the technology. The history belonging to the drawbacks of technology, along with several have weakness in color performance in the movie and can not be copied, especially in very bright or very dark picture of the regional details of stains.
In addition to technical problems, the shortcomings of the other liquid crystal display has been the historical cost. If space is not a problem, the current cathode ray tube the cost-effective solutions. Panel prices have declined rapidly, especially where supply has outstripped demand in the second half of this year. This has led many manufacturers to lower prices, although some people also cut production to bring supply / demand curve back.
In this article, we will have a better video reproduction, the use of TFT - LCD's some new technology, and how the strain to take measures to reduce the cost of violations of one's drive.
lcd display module assembly
Figure 1 shows a typical circuit, liquid crystal display module . Both notebook panel, desktop monitor or television applications and design, all of capabilities are required, numerous of the performance of each product are different.
Timing Controller is really a digital IC is really a core member for the panel. It is commonly employed to control the liquid crystal display for controlling data writing mechanism is answerable to regular scans. Unit fitted reset row and column driver did start to write at the top of the monitor as well as the scan data several line in backside of the reveal. The line driver was usually choose which lines are at a specific time to write its data, the facility transmission. Column driver into digital video data in your whole analog voltage input to the display each pixel .
Each LCD panel clearly need an energy supply. The group four main power current. Main power supply (AVDD) provide a high voltage for driving LCD display in analog integrated circuits, including the column used to operate a vehicle to the display itself, the image of the contents of the driver a lot. Although many people in the TFT - LCD monitor as an electronic display, the brightness of each pixel is actually stored by an analog voltage at the pixel level. Pixel RGB filters in-front to make color reproduction. Because dynamics of the display of the simulation, AVDD power supply rails have to provide good load regulation, and supply sufficient current to charge and discharge pixel within the display capacity very quickly. Other items in the display, including products for the digital logic IC supply and a better voltage and negative voltage Von VOFF This is used to display the internal power line car owner. For high-performance video display, which is very important unit high-performance TFT - LCD regulator to relieve the image distortion and smearing. Devices like the EL7585 (Figure 2) includes all these belongings in one IC 4, and also includes power sequencing it is crucial to avoid damage to the LCD display
Fig. three. EL7585 LCD supply voltage generated four
The VCOM amplifier is used to provide a display of pixels are highly stable reference voltage. About 50 % of this supply is often a typical associated with AVDD and also the brightness each pixel through column driver that drives VCOM voltage between the voltage difference determined.
Between pixels from one and ascribed to the light it emits is a nonlinear relationship between voltage relationship. The so-called gamma curve '(Figure 3) is actually an S - curve nature, which can be negative or positive reference to VCOM. In fact, harming the alternate uses of a real panel switch polarity, additional pixels. Arrive at an average DC voltage across screen 0V, burns and other effects in order to prevent the offset related. As each group has a different gamma curve response, the column drivers need a reference curve, so that can correct voltage drive each pixel to obtain the necessary sunshine. These curves are conventional the supply and use gamma buffer and a resistor string can be used to simulate the competitors.
Figure two to three. S-shaped gamma curve, a pixel from among the displayed and applied for the voltage with the light it emits isn't linear.
In our block diagram of closing device is really a LCD backlight lcd vehicle driver. Today, almost all of the LCD panel using CCFL (cold cathode fluorescent lamp) backlight. These types of the LCD panel itself does n't want light, however in fact on or off, from the sunshine source behind the door. The CCFL device needs very high voltage AC waveform to drive them. General notebook computers and monitors can use only one CCFL controller for every panel. However, a large panel, TV monitor which should be a brighter backlight, the impulse for more cold cathode fluorescent lamps, so more drivers. From each individuals CCFL light also must match or brightness on the image along the screen will be different.
Reduce motion blur
Watch video on the LCD screen with one of the biggest is motion blur. This effect comes to the LCD display is very slow to respond, in order to the back of is acceptable of any appearance connected with a smear campaign. Today, LCD technology is 12 ms to 16 ms produced within the response hours. Although much faster than 20ms is 30 milliseconds for a few years ago, this may be fast enough to completely eliminate this artifact. Of course, this has been improvement of key areas and also the LCD at the moment used decrease a connected with technical problems.
LCD panel from top of probably the most obvious option would be to hasten the response of lcd tv material. Present-day materials can improve the response over drive each pixel. However, this still does not produce rapid response is required. Although some companies display and 5 ms (gray to gray) response time of the new materials and gray, black, about 1 millisecond time. Fast gray-black, additionally, they started make successful use of the black insertion (see Figure 4). Fractional treatments is into an image of a black frame in between each frame. However it create intense pulse, much the CRT monitor. A persons brain filters out the flash and automatically generates intermediate snap shots. The technology demonstration at the recent exhibition proved very effective.
Figure eight. Insert an image onto a black frame between each black parcel. This will create a rapid pulse, much the CRT display, the human being brain integration, to effect the motion.
If the LCD isn't available quickly, this effect can be also simulated pulse backlighting. Method also turned out to be be useful. From the top in the final by the Ministry of scanning backlight, and further elimination to move artifacts, can move in very sharp images.
Offset by the LCD panel, the required voltage VCOM is slightly different coming from an ideal one and a half AVDD. In turn, may lead to the appearance from the display whizzes. To eliminate this effect, VCOM frequently adjusted across the panel by the panel of blinking, so that the is removed. This pot is being replaced by machinery of these offsets, the automated adjustment, eliminating the opportunity of human error and bias, through a digital potentiometer. Figure 5a shows the driving EL5111 Intersil's ISL45041 VCOM amplifiers, high power software program.