laptop lcd panel voltage brands
Monochrome character, graphic and static displays require different input voltages. All the different LCD voltage symbols can be confusing, but believe it or not, there is a system to the madness.
The voltages VCC, VDD, VSS and VEE are used in describing voltages at various common power supply terminals. The differences between these voltages stem from their origins in the transistor circuits they were originally used for.
This LCD voltage terminology originated from the terminals of each type of transistor and their common connections in logic circuits. In other words, VCC is often applied to BJT (Bipolar Junction Transistor) collectors, VEE to BJT emitters, VDD to FET (Field-Effect Transistor) drains and VSS to FET sources. Most CMOS (Complementary metal–oxide–semiconductor) IC data sheets now use VCC and GND to designate the positive and negative supply pins.
In the Pleistocene era (1960’s or earlier), logic was implemented with bipolar transistors. NPN (Negative-Positive-Negative) were used because they were faster. It made sense to call positive supply voltage VCC where the “C” stands for collector. The negative supply was called VEE where “E” stands for emitter.
When FET transistor logic came around a similar naming convention was used, but now positive supply was VDD where “D” stands for drain. The negative supply was called VSS where “S” stands for source. Now that CMOS is the most common logic this makes no sense. The “C” in CMOS is for “complementary” but the naming convention still persists. In practice today VCC/VDD means positive power supply voltage and VEE/VSS is for negative supply or ground.
The convention of VAB means the voltage potential between VA and VB. The convention of using 3 letters was used to show power supply and ground reference voltages as well. In some cases a processor may have both an analog and digital power supply. In this case VCCA/VCCD and VSSA/VSSD are used. Another reason for the 3 letters is in an NPN circuit with a load resister between the collector and VCC. VC would be the collector voltage. In this case VCC is the positive power supply voltage and would be higher than VC.
Pin three (3) is Vo and is the difference in voltage between VDD and VSS. This LCD voltage is adjusted to provide the sharpest contrast. The adjustment can be accomplished through a fixed resistor or a variable potentiometer. Many products have firmware that monitor the temperature and automatically adjust the contrast voltage.
In a Liquid Crystal Display (LCD), V0 is used to vary the screen brightness or contrast. Contrast, simply put is the ratio of the light areas to the dark areas in a LCD. This is usually done in a production setting with values which are optimized for most users. Temperature can have an undesirable effect on the display brightness and for this reason a varying resister or potentiometer is used to accommodate the desires of the user.
Below is a data sheet of a 16x2 Character LCD module that shows various recommended driving voltages. The LCD voltage can range from MIN (minimum) to TYP (Typical) to Max (maximum).
If the supplied LCD voltage drops too low, the display is ‘under-driven’ and will produce segments that are ‘grey’. The lower the LCD voltage falls below the acceptable threshold, the lower the contrast will be.
If the LCD is over-driven, you may see ghosting. This is where segments that should not be ‘on’ are gray. They are not as dark as the segments that should be on, but they can be seen and may cause confusion for the end user.
There are times when a customer needs to replace a display that has been discontinued or EOL (End-Of -Life) by their previous LCD supplier. The previous LCD’s pin-outs may be different than Focus’ standard, off-the-shelf display. This is not a large problem to overcome.
The third option is to pull power from pins one and two. This is the same location from which the LCD is pulling its power. Focus does not recommend this option and can modify the PCB for the customer to connect the backlight from a different location.
Many LCD Modules will require more than one internal voltage/current. This may make it necessary for the customer to supply the needed inputs. They may need to supply 3V, 5V, 9V, -12V etc.
The solution for this is to integrate a charge pump (or booster circuit) into the LCD circuitry. This solution works in most applications, but if the product will be operating in an intrinsic environment, care must be taken with layout of the circuit board.
Intrinsically-safe LCDs are Liquid Crystal Displays that are designed to operate in conditions where an arc or spark can cause an explosion. In these cases, charge pumps cannot be employed. In fact, the total capacitive value of the display needs to be kept to a minimum.
Focus Display Solutions does not build a display that is labeled ‘Intrinsically safe’ but we do design the LCD to meet the requirements of the engineer. In meeting the design engineer’s requirements, the display may need to contain two or three independent inputs. Focus can redesign the PCB and lay out the traces to allow for these additional inputs.
Just like televisions, laptop displays start to flicker too after a few years. You may sometimes also notice the display turning blank even when the laptop is on. Alternatively, you might find some white lines running down the display.
This doesn’t necessarily mean that there is an issue with the motherboard. If your laptop keeps turning off every few minutes and doesn’t turn on, there is a high chance that the AC adapter has malfunctioned. You can get help from a professional to confirm and get the AC adapter replaced, if required. There is also a possibility that the DC power jack may have broken. A DC connector (or DC plug) is an electrical connector that supplies steady power to the device.
If you ever notice multi-coloured or single-coloured vertical lines on your laptop screen, it may be a result of a hardware failure or due to damage to the screen. To try fixing it yourself, first unplug your laptop, hold the power button for 30 seconds and restart the laptop. If you continue to see coloured lines, the issue is probably with the LCD screen, which will need to be replaced from the brand’s service center. To be sure about the LCD screen problem, try connecting your laptop to another monitor and see if the issue persists. If it does, the issue is certainly in the LCD panel.
On turning on the laptop when you see the lights blinking and hear the fan working but if the laptop screen is blank and doesn’t display anything, this is again an indication of a faulty motherboard. The first thing to do is to transfer all the data to another drive to make sure your data is safe. Before going ahead and getting the motherboard repaired or replaced, you could try performing a hard reset (also known as a factory reset), which can mostly help in resolving the blank display issue.
Firstly, check if your laptop’s brightness level is set to maximum. If the display is still dim, try restarting the device. This could just be a system error that can be resolved by restarting the device. Also, check if the AC adapter cord is loose and firmly connect it to the outlet and laptop. If the issue still persists, it is mostly due to a failure of the LCD. Behind the LCD, there is an inverter board and backlight bulb which control the picture.
The inverter board converts the low voltage your laptop uses, into higher voltage required by the long bulb that lights up the LCD screen. If the inverter board or bulb fail, you will experience the problem of a dimmed display. Even if one of these two components fail, the screen will need to be replaced, unless the service center can help by just replacing the bulb. We wouldn’t recommend you try resolving it yourself, as this is more complex and you could end up damaging the circuit board and the backlight lamp. So, it’s best to leave this job to an expert.
Laptops are fragile and can easily break, especially with more and more thinner and lighter models being launched now. Some of the most common ways how a laptop is damaged include: when it accidentally falls and the screen cracks, when it’s held at an awkward angle or if you unknowingly placed something heavy on the laptop. Remember, a cracked laptop screen can affect the overall functioning of the device in some cases.
Since brands do not cover the laptop screen, it’s best to get your device covered with a protection plan in advance. Screen replacements are expensive and can cost you anywhere up to Rs. 15,000 but if you have the
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IPS (in-plane switching) is a screen technology for liquid-crystal displays (LCDs). In IPS, a layer of liquid crystals is sandwiched between two glass surfaces. The liquid crystal molecules are aligned parallel to those surfaces in predetermined directions (in-plane). The molecules are reoriented by an applied electric field, whilst remaining essentially parallel to the surfaces to produce an image. It was designed to solve the strong viewing angle dependence and low-quality color reproduction of the twisted nematic field effect (TN) matrix LCDs prevalent in the late 1980s.
The TN method was the only viable technology for active matrix TFT LCDs in the late 1980s and early 1990s. Early panels showed grayscale inversion from up to down,Vertical Alignment (VA)—that could resolve these weaknesses and were applied to large computer monitor panels.
Shortly thereafter, Hitachi of Japan filed patents to improve this technology. A leader in this field was Katsumi Kondo, who worked at the Hitachi Research Center.thin-film transistor array as a matrix and to avoid undesirable stray fields in between pixels.Super IPS). NEC and Hitachi became early manufacturers of active-matrix addressed LCDs based on the IPS technology. This is a milestone for implementing large-screen LCDs having acceptable visual performance for flat-panel computer monitors and television screens. In 1996, Samsung developed the optical patterning technique that enables multi-domain LCD. Multi-domain and in-plane switching subsequently remain the dominant LCD designs through 2006.
IPS technology is widely used in panels for TVs, tablet computers, and smartphones. In particular, most IBM products was marketed as CCFL backlighting, and all Apple Inc. products marketed with the label backlighting since 2010.
Most panels also support true 8-bit-per-channel colour. These improvements came at the cost of a lower response time, initially about 50 ms. IPS panels were also extremely expensive.
In this case, both linear polarizing filters P and A have their axes of transmission in the same direction. To obtain the 90 degree twisted nematic structure of the LC layer between the two glass plates without an applied electric field (OFF state), the inner surfaces of the glass plates are treated to align the bordering LC molecules at a right angle. This molecular structure is practically the same as in TN LCDs. However, the arrangement of the electrodes e1 and e2 is different. Because they are in the same plane and on a single glass plate, they generate an electric field essentially parallel to this plate. The diagram is not to scale: the LC layer is only a few micrometers thick and so is very small compared with the distance between the electrodes.
The LC molecules have a positive dielectric anisotropy and align themselves with their long axis parallel to an applied electrical field. In the OFF state (shown on the left), entering light L1 becomes linearly polarized by polarizer P. The twisted nematic LC layer rotates the polarization axis of the passing light by 90 degrees, so that ideally no light passes through polarizer A. In the ON state, a sufficient voltage is applied between electrodes and a corresponding electrical field E is generated that realigns the LC molecules as shown on the right of the diagram. Here, light L2 can pass through polarizer A.
Unlike TN LCDs, IPS panels do not lighten or show tailing when touched. This is important for touch-screen devices, such as smartphones and tablet computers.
Toward the end of 2010 Samsung Electronics introduced Super PLS (Plane-to-Line Switching) with the intent of providing an alternative to the popular IPS technology which is primarily manufactured by LG Display. It is an "IPS-type" panel technology, and is very similar in performance features, specs and characteristics to LG Display"s offering. Samsung adopted PLS panels instead of AMOLED panels, because in the past AMOLED panels had difficulties in realizing full HD resolution on mobile devices. PLS technology was Samsung"s wide-viewing angle LCD technology, similar to LG Display"s IPS technology.
In 2012 AU Optronics began investment in their own IPS-type technology, dubbed AHVA. This should not be confused with their long standing AMVA technology (which is a VA-type technology). Performance and specs remained very similar to LG Display"s IPS and Samsung"s PLS offerings. The first 144 Hz compatible IPS-type panels were produced in late 2014 (used first in early 2015) by AUO, beating Samsung and LG Display to providing high refresh rate IPS-type panels.
Baker, Simon (30 April 2011). "Panel Technologies: TN Film, MVA, PVA and IPS Explained". Tftcentral.co.uk. Archived from the original on 29 June 2017. Retrieved 13 January 2012.
A plasma display panel (PDP) is a type of flat panel display that uses small cells containing plasma: ionized gas that responds to electric fields. Plasma televisions were the first large (over 32 inches diagonal) flat panel displays to be released to the public.
Until about 2007, plasma displays were commonly used in large televisions (30 inches (76 cm) and larger). By 2013, they had lost nearly all market share due to competition from low-cost LCDs and more expensive but high-contrast OLED flat-panel displays. Manufacturing of plasma displays for the United States retail market ended in 2014,
Plasma displays are bright (1,000 lux or higher for the display module), have a wide color gamut, and can be produced in fairly large sizes—up to 3.8 metres (150 in) diagonally. They had a very low luminance "dark-room" black level compared with the lighter grey of the unilluminated parts of an LCD screen. (As plasma panels are locally lit and do not require a back light, blacks are blacker on plasma and grayer on LCD"s.)LED-backlit LCD televisions have been developed to reduce this distinction. The display panel itself is about 6 cm (2.4 in) thick, generally allowing the device"s total thickness (including electronics) to be less than 10 cm (3.9 in). Power consumption varies greatly with picture content, with bright scenes drawing significantly more power than darker ones – this is also true for CRTs as well as modern LCDs where LED backlight brightness is adjusted dynamically. The plasma that illuminates the screen can reach a temperature of at least 1200 °C (2200 °F). Typical power consumption is 400 watts for a 127 cm (50 in) screen. Most screens are set to "vivid" mode by default in the factory (which maximizes the brightness and raises the contrast so the image on the screen looks good under the extremely bright lights that are common in big box stores), which draws at least twice the power (around 500–700 watts) of a "home" setting of less extreme brightness.
Plasma screens are made out of glass, which may result in glare on the screen from nearby light sources. Plasma display panels cannot be economically manufactured in screen sizes smaller than 82 centimetres (32 in).enhanced-definition televisions (EDTV) this small, even fewer have made 32 inch plasma HDTVs. With the trend toward large-screen television technology, the 32 inch screen size is rapidly disappearing. Though considered bulky and thick compared with their LCD counterparts, some sets such as Panasonic"s Z1 and Samsung"s B860 series are as slim as 2.5 cm (1 in) thick making them comparable to LCDs in this respect.
Wider viewing angles than those of LCD; images do not suffer from degradation at less than straight ahead angles like LCDs. LCDs using IPS technology have the widest angles, but they do not equal the range of plasma primarily due to "IPS glow", a generally whitish haze that appears due to the nature of the IPS pixel design.
Superior uniformity. LCD panel backlights nearly always produce uneven brightness levels, although this is not always noticeable. High-end computer monitors have technologies to try to compensate for the uniformity problem.
Unaffected by clouding from the polishing process. Some LCD panel types, like IPS, require a polishing process that can introduce a haze usually referred to as "clouding".
Uses more electrical power, on average, than an LCD TV using a LED backlight. Older CCFL backlights for LCD panels used quite a bit more power, and older plasma TVs used quite a bit more power than recent models.
Fixed-pixel displays such as plasma TVs scale the video image of each incoming signal to the native resolution of the display panel. The most common native resolutions for plasma display panels are 852×480 (EDTV), 1,366×768 and 1920×1080 (HDTV). As a result, picture quality varies depending on the performance of the video scaling processor and the upscaling and downscaling algorithms used by each display manufacturer.
Early high-definition (HD) plasma displays had a resolution of 1024x1024 and were alternate lighting of surfaces (ALiS) panels made by Fujitsu and Hitachi.
A panel of a plasma display typically comprises millions of tiny compartments in between two panels of glass. These compartments, or "bulbs" or "cells", hold a mixture of noble gases and a minuscule amount of another gas (e.g., mercury vapor). Just as in the fluorescent lamps over an office desk, when a high voltage is applied across the cell, the gas in the cells forms a plasma. With flow of electricity (electrons), some of the electrons strike mercury particles as the electrons move through the plasma, momentarily increasing the energy level of the atom until the excess energy is shed. Mercury sheds the energy as ultraviolet (UV) photons. The UV photons then strike phosphor that is painted on the inside of the cell. When the UV photon strikes a phosphor molecule, it momentarily raises the energy level of an outer orbit electron in the phosphor molecule, moving the electron from a stable to an unstable state; the electron then sheds the excess energy as a photon at a lower energy level than UV light; the lower energy photons are mostly in the infrared range but about 40% are in the visible light range. Thus the input energy is converted to mostly infrared but also as visible light. The screen heats up to between 30 and 41 °C (86 and 106 °F) during operation. Depending on the phosphors used, different colors of visible light can be achieved. Each pixel in a plasma display is made up of three cells comprising the primary colors of visible light. Varying the voltage of the signals to the cells thus allows different perceived colors.
Control circuitry charges the electrodes that cross paths at a cell, creating a voltage difference between front and back. Some of the atoms in the gas of a cell then lose electrons and become ionized, which creates an electrically conducting plasma of atoms, free electrons, and ions. The collisions of the flowing electrons in the plasma with the inert gas atoms leads to light emission; such light-emitting plasmas are known as glow discharges.
In a monochrome plasma panel, the gas is mostly neon, and the color is the characteristic orange of a neon-filled lamp (or sign). Once a glow discharge has been initiated in a cell, it can be maintained by applying a low-level voltage between all the horizontal and vertical electrodes–even after the ionizing voltage is removed. To erase a cell all voltage is removed from a pair of electrodes. This type of panel has inherent memory. A small amount of nitrogen is added to the neon to increase hysteresis.phosphor. The ultraviolet photons emitted by the plasma excite these phosphors, which give off visible light with colors determined by the phosphor materials. This aspect is comparable to fluorescent lamps and to the neon signs that use colored phosphors.
Every pixel is made up of three separate subpixel cells, each with different colored phosphors. One subpixel has a red light phosphor, one subpixel has a green light phosphor and one subpixel has a blue light phosphor. These colors blend together to create the overall color of the pixel, the same as a triad of a shadow mask CRT or color LCD. Plasma panels use pulse-width modulation (PWM) to control brightness: by varying the pulses of current flowing through the different cells thousands of times per second, the control system can increase or decrease the intensity of each subpixel color to create billions of different combinations of red, green and blue. In this way, the control system can produce most of the visible colors. Plasma displays use the same phosphors as CRTs, which accounts for the extremely accurate color reproduction when viewing television or computer video images (which use an RGB color system designed for CRT displays).
Plasma displays are different from liquid crystal displays (LCDs), another lightweight flat-screen display using very different technology. LCDs may use one or two large fluorescent lamps as a backlight source, but the different colors are controlled by LCD units, which in effect behave as gates that allow or block light through red, green, or blue filters on the front of the LCD panel.
To produce light, the cells need to be driven at a relatively high voltage (~300 volts) and the pressure of the gases inside the cell needs to be low (~500 torr).
Each cell on a plasma display must be precharged before it is lit, otherwise the cell would not respond quickly enough. Precharging normally increases power consumption, so energy recovery mechanisms may be in place to avoid an increase in power consumption.LED illumination can automatically reduce the backlighting on darker scenes, though this method cannot be used in high-contrast scenes, leaving some light showing from black parts of an image with bright parts, such as (at the extreme) a solid black screen with one fine intense bright line. This is called a "halo" effect which has been minimized on newer LED-backlit LCDs with local dimming. Edgelit models cannot compete with this as the light is reflected via a light guide to distribute the light behind the panel.
Image burn-in occurs on CRTs and plasma panels when the same picture is displayed for long periods. This causes the phosphors to overheat, losing some of their luminosity and producing a "shadow" image that is visible with the power off. Burn-in is especially a problem on plasma panels because they run hotter than CRTs. Early plasma televisions were plagued by burn-in, making it impossible to use video games or anything else that displayed static images.
In 1983, IBM introduced a 19-inch (48 cm) orange-on-black monochrome display (Model 3290 Information Panel) which was able to show up to four simultaneous IBM 3270 terminal sessions. By the end of the decade, orange monochrome plasma displays were used in a number of high-end AC-powered portable computers, such as the Compaq Portable 386 (1987) and the IBM P75 (1990). Plasma displays had a better contrast ratio, viewability angle, and less motion blur than the LCDs that were available at the time, and were used until the introduction of active-matrix color LCD displays in 1992.
Due to heavy competition from monochrome LCDs used in laptops and the high costs of plasma display technology, in 1987 IBM planned to shut down its factory in Kingston, New York, the largest plasma plant in the world, in favor of manufacturing mainframe computers, which would have left development to Japanese companies.Larry F. Weber, a University of Illinois ECE PhD (in plasma display research) and staff scientist working at CERL (home of the PLATO System), co-founded Plasmaco with Stephen Globus and IBM plant manager James Kehoe, and bought the plant from IBM for US$50,000. Weber stayed in Urbana as CTO until 1990, then moved to upstate New York to work at Plasmaco.
In 1995, Fujitsu introduced the first 42-inch (107 cm) plasma display panel;Philips introduced the first large commercially available flat-panel TV, using the Fujitsu panels. It was available at four Sears locations in the US for $14,999, including in-home installation. Pioneer also began selling plasma televisions that year, and other manufacturers followed. By the year 2000 prices had dropped to $10,000.
In late 2006, analysts noted that LCDs had overtaken plasmas, particularly in the 40-inch (100 cm) and above segment where plasma had previously gained market share.
Until the early 2000s, plasma displays were the most popular choice for HDTV flat panel display as they had many benefits over LCDs. Beyond plasma"s deeper blacks, increased contrast, faster response time, greater color spectrum, and wider viewing angle; they were also much bigger than LCDs, and it was believed that LCDs were suited only to smaller sized televisions. However, improvements in VLSI fabrication narrowed the technological gap. The increased size, lower weight, falling prices, and often lower electrical power consumption of LCDs made them competitive with plasma television sets.
At the 2010 Consumer Electronics Show in Las Vegas, Panasonic introduced their 152" 2160p 3D plasma. In 2010, Panasonic shipped 19.1 million plasma TV panels.