normally white transmissive lcd panel for sale

In theory, a material that perfectly reflects all light energy at every visible wavelength. In practice, a solid white (with known spectral data) that is used as the "reference white" for all measurements of absolute reflectance.

A liquid crystal display structure in which switching transistors or diodes are attached to each pixel to control the on/off voltage. It produces a brighter and sharper display with a broader viewing angle than a passive matrix display. Also known as AMLCD (active matrix liquid crystal display). See TFT (thin film transistor).

A type of flat panel display in which each pixel has it"s own transistor `switch" rather than being activated by it"s address within a matrix of rows and columns. This direct switching radically improves response times enabling full-motion video to be shown without blurring.

The most common type of LCD (Liquid Crystal Display) used in the majority of laptops and most LCD panels and projectors. A typical active matrix TFT display is a single panel of LCD glass that modulates all three primary colors. Most of these offer contrast ratios up to 100:1 for good color dynamics, and just enough speed to handle video and 30fps multimedia with little or barely distinguishable hesitation (jerkiness).

In color reproduction, red, green, and blue. When lights in these colors are combined in equal amounts, they produce the visual sensation of white light. When these are combined at varying intensities, a range of different colors is produced. Combining two primaries at 100% produces a subtractive primary, either cyan, magenta, or yellow. See subtractive primaries.

LCD monitors with an analog interface can accept an analog video signal using standard RGB connectors for personal computers, in the same way as a CRT monitor. The analog signal is then converted into the digital signal used for display on a LCD panel. LCD monitors with only a digital interface require a dedicated graphics adapter and connectors, which come in varied formats.

A treated glass panel that is placed over a monitor screen to reduce glare from light sources. Non-glare CRTs often use a coating baked onto the screen at the time of manufacture, which provides a significant reduction in glare; however, LCD screens may completely eliminate it.

The ratio between the transmissive portion of the pixel and its surrounding electronics, also known as fill factor. Generally, this is a limiting factor for luminance, the higher the aperture ratio; the brighter the luminance.

A special one-touch Auto Adjust button allows users to quickly set the display panel to match their preferences and provides users with excellent front-of-screen performance and minimal set up.

The light source for a transmissive LCD. Basically, two techniques are used in transmissive LCD designs, direct lighting and side lighting. Direct-lit backlights use CCFTs (cold cathode fluorescent tubes) and a diffuser panel directly in back of the LC (liquid crystal) layer. Side-lit backlights use CCFTs and a light pipe on one or more of the edges of the display.

A technique used to make flat-panel displays easier to read in low ambient light conditions. The most commonly used types of backlighting are LED, EL (electro luminescent) or CCFL (Cold Cathode Fluorescent).

Refers to a remote control, or on projector control panel, that has buttons and controls that are illuminated. This is a major asset when using the projector in a darkened or semi-darkened room. Many projectors have backlit remote controls, while the number of projectors with backlit control panels is much smaller. As projectors have gotten brighter, room lights tend to stay on, so while nice, having backlit controls is no longer important to many users.

A metal or plastic frame which fits over the LCD glass to protect the edges of the glass. The bezel acts as a pressure device, compressing the elastomer connector between the LCD glass and PCB.

The dimension of color that is referred to an achromatic scale, ranging from black to white, also called lightness or luminous reflectance. Because of confusion with saturation, the use of this term should be discouraged.

A technique where the alignment layer on the LCD substrate is rubbed in one or more directions. This process aligns the liquid crystal molecules parallel to the buffing direction. See alignment layer.

These are the fluorescent tubes that provide the light for the LCD unit. These tubes are generally very thin, approximately 2 mm in diameter. See fluorescent lamp.

The LCD driver is formatted into an area on the PCB. Electrical connections are made by micro diameter gold wires. The entire area is then covered with epoxy.

In LCD graphic modules, a type of fluorescent backlighting or edge lighting. One or more fluorescent lamps behind the LCD panel that provides the light that is either blocked (black) or passed (white) by the LCD cell. Used in medium to large size graphic LCD modules.

Color matching refers to the process of accurate duplication of colors between the display and either input (like a VGA card) or output (like a printer). An LCD display with color matching stores color-related parameters in special memory called EEPROM, and uses this data for optimization, providing benefits such as WYSIWYG printing and faithful representation of Web graphics.

A measurement of the color of light radiated by an object while it is being heated. This measurement is express in terms of absolute scale, or degrees Kelvin. Lower Kelvin temperatures such as 2400� K are red; higher temperatures such as 9300� K are blue. Neutral temperature is white, at 6504� K.

The difference in luminance between a white square centered on the screen and the black surrounding area. A method of measuring the dynamic range. A contrast ratio of 15:1 (passive matrix LCDs), offers washed out colors, little detail and image that can barely survive with significant ambient light. Projectors with active matrix TFTs have ratios to 100:1, DLPs from 125:1 and Poly-Si Liquid Crystal Displays 200:2.By comparison, transparency film (i.e. 35mm slides) have contrast ratios over 500:1.

A row or block of dots, used to indicate the location of the next character or symbol to be entered. Used in dot matrix character and graphic LCD modules.

TFT LCD panels support either 6-bit or 8-bit RGB color output, allowing them to display 262K or 16.7M distinct colors, respectively. Using so-called dithering techniques, an analog-to-digital signal processor can simulate 8-bit RGB color output on an LCD panel that actually supports only 6-bit color.

The smallest active element that forms all text and graphics on the LCD screen. Typically a rectangular active element, when combined together in a matrix, forms a character or symbol.

A passive matrix LCD (Liquid Crystal Display) technology that uses an extra compensating layer to provide a sharper image, sometimes called F-STN or Film Compensated Supertwist.

An enhanced STN passive matrix LCD (Liquid Crystal Display). The screen is divided into halves and each half is scanned simultaneously, thereby doubling the number of lines refreshed per second and providing a sharper appearance. DSTN is widely used on laptops and Point of Sale Terminals.

A type of passive matrix LCD (Liquid Crystal Display) that provides faster refresh rates than conventional passive matrix displays by dividing the screen into two sections that are refreshed simultaneously.Dual scan displays are generally not as sharp or bright as active matrix displays, but they consume less power.

A technology used to produce a very thin display screen, called a flat panel display, used in some portable equipment. An ELD works by sandwiching a thin film of phosphorescent substance between two plates. One plate is coated with vertical wires and the other with horizontal wires, forming a grid.When an electrical current is passed through a horizontal and vertical wire, the phosphorescent film at the intersection glows, creating a point of light or pixel.EL Displays, being an emissive technology (rather than shuttering a light source as per LCDs) are most useful in applications where high visibility in all light conditions is essential.

A strip of silicone rubber made up of sequentially spaced conductive and non-conductive material. This is the most common connection method for LCD modules.

A phenomenon which occurs when excess DC voltage is applied to an LCD. Conductive particles from one piece of glass are transferred through the LC fluid and deposited on the conductive surface of the opposite piece of glass. A conductive spike is created thus causing a dead short.

A space left between the epoxy seals, after assembly on one end of the LCD glass. This space is used to fill the glass with the LC fluid, which is noted by a mound of epoxy on one end of the glass.

A very thin display screen used in portable computers. Nearly all modern flat panel displays use LCD (Liquid Crystal Display) technologies.Most LCD screens are backlit to make them easier to read in bright environments. Another example of a flat panel display is the gas plasma display screen.

A phenomenon occurring when voltage from an energized element leaks to an adjacent OFF element and turns the adjacent element partially ON. Also, the temporary trail left by a moving object on a "slow" LCD panel

An achromatic scale ranging from black through a series of successively lighter grays to white. Such a series may be made up of steps, which appear to be equally distant from one another or may be arranged according to some other criteria such as a geometric progression based on lightness.

A screen that uses one of many methods to collect light and reflect it back to the audience, which dramatically increase the brightness of the image over a white wall or semi-matte screen. Technologies used include curved screens, special metal foil screens (some polarized), and certain glass bead screens. Prices and performance vary tremendously, but attention to the screen can make a big difference, particularly in "tough" environments such as trade shows.

The main attribute of a color that distinguishes it from other colors. For example, a color may have a green, yellow, or purple hue. Colors defined as having hue are known as chromatic colors. White, black, and grays possess no hue.

A liquid crystal technology in which the alignment field is generated from electrodes located on a single substrate rather than on opposite sides like more conventional (TN) panels. The main advantages IPS are greater viewing angles and greater contrast ratio.

Used exclusively on negative image graphic displays (transmissive negative). With EL or cold cathode backlight where the background is energized and the information to be displayed remains static or the same color as the polarizer in the OFF state. This is achieved by inverting the signal of the data lines before going to the LCD module.

A technique of improving the viewing angle of an LCD where the liquid crystal molecules are switched in the plane of the LCD layer rather than vertical to it.

LCD, an abbreviation of Liquid Crystal Display, is a type of display used in digital watches and many portable devices. LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal, therefore, is like a shutter, either allowing light to pass through or blocking the light.Monochrome LCD images usually appear as blue or dark gray images on top of a grayish-white background. Color Liquid Crystal Displays use two basic techniques for producing color. Passive matrix is the less expensive of the two technologies.The other technology, called thin film transistor (TFT) or active matrix produces color images that are as sharp as traditional CRT displays, but the technology is relatively expensive.Recent passive matrix displays using new CSTN and DSTN technologies produce sharp colors rivaling active matrix displays.Most Liquid Crystal Display screens used in notebook computers are backlit to make them easier to read.

A monitor that uses LCD (Liquid Crystal Display) technologies rather than the conventional CRT technologies used by most desktop monitors.Until recently, LCD panels were used exclusively in notebook computers (laptops) and other portable devices. In 1997, however, several manufacturers began offering full-size Liquid Crystal Display Monitors as alternatives to CRT monitors.The main advantage of LCD displays is that they take up less desk space and are lighter. Currently, however, they are also much more expensive

LCD (Liquid Crystal Display) is the technology used for displays in notebook, smaller computers, portable devices including Mobile Telecoms (Telecommunication) pagers, phones, PDAs, EPOS and other instrumentation monitors. Like light-emitting diode and gas-plasma technologies, LCDs allow displays to be much thinner than cathode ray tube (CRT) technology. Liquid crystal Displays consume much less power than LED and gas displays because they work on the principle of shuttering light rather than emitting it.LCD fluids are selectable for individual display projects, with TN the original technology and HTN, STN and F-STN being developments. Liquid crystal displays are the most popular display medium for applications large and small.An LCD is made with either a passive matrix or an active matrix display grid. The active matrix LCD is also known as a thin film transistor (TFT) display. The passive matrix LCD has a grid of conductors with pixels located at each intersection in the grid. A current is sent across two conductors on the grid to control the light for any pixel. An active matrix has a transistor located at each pixel intersection, requiring less current to control the luminance of a pixel. For this reason, the current in an active matrix display can be switched on and off more frequently, improving the screen refresh time (your mouse will appear to move more smoothly across the screen, for example).A typical liquid crystal display will incorporate the LCD fluid (either TN, STN, HTN or F-STN) in a glass envelope with ITO coatings to the internal glass surfaces. The basic liquid crystal display, either statically driven or multiplexed, is frequently incorporated onto a PCB (Printed Circuit Board) with the LCD display driver hardware and often backlighting, LED EL, or CCFL.Liquid crystal displays do not suffer degradation over time, the LCD fluids always return to their normal state when a voltage is not applied. Temperature does affect liquid crystal displays however, with extreme low temperature causing the LCD to respond very slowly. The required bias voltage across the liquid crystal display also alters with ambient temperature.Some passive matrix liquid crystal displays have dual scanning, meaning that they scan the grid twice with current in the same time that it took for one scan in the original technology. However, active matrix is still a superior technology.Temperature does affect liquid crystal displays, however with extreme low temperature causing the LCD to respond very slowly. The required bias voltage across the liquid crystal display also alters with ambient temperature

Also called a projection panel, it is a data projector that accepts computer output and displays it on a transmissive liquid crystal screen that is placed on top of an overhead projector.Liquid crystal display systems are also available with their own light source. Such units generally provide the best quality, because the light and lenses are fine tuned to the built-in LCD screen.

A form of backlighting for small to medium size LCDs that use surface mount LEDs on a substrate with a light diffuser over the top. In some cases LEDs are placed at each end of the module and light is directed into the center.

The compound found in liquid crystal displays. Liquid crystal reacts predictably when electrically stimulated. This makes it the ideal compound to turn LCD pixels "on" or "off." Liquid crystal is sometimes abbreviated as LC.

(Low Voltage Differential Signalling) A transmission method for sending digital information to a flat panel display. LVDS has been widely used in laptops because it enables fewer wires to be used between the motherboard and the panel. The technology is also used between the image scaler and the panel in many stand-alone flat panel displays.

For LCD Monitors designed in compliance with VESA Standard Physical Mounting Interface Standard (FPMPM), users may choose mounting solutions from professional arm manufacturers.

Unlike traditional CRTs that can display multiple resolutions, LCD displays are manufactured to best display a single resolution, known as the native resolution. While it may be possible to change the resolution of an LCD (depending on the video card and software used with the LCD), setting the resolution to something other than the native resolution will result in a stretched image, a blurry image, or no image on the screen at all. This is typically expressed as the number of pixels in a line by the number of lines, e.g. 1024x768. The native resolution may also be expressed in megapixels, which is calculated by multiplying pixels per line by total lines.

A twisted nematic LCD design where the backlight is blocked when pixels are in the unselected state. Therefore, when no voltage is applied, the screen is black.

A twisted nematic LCD design where light is transmitted when pixels are in the unselected state. Therefore, when no voltage is applied, the screen is white.

(On-Screen Display) An on-screen control panel for adjusting monitors and TVs. The OSD is used for contrast, brightness, horizontal and vertical positioning and other monitor adjustments.

The predecessor to today"s projectors, (some are still available) they a thin (under 2") devices typically 10 x 14 inches. All panels are of the LCD variety. They lack their own light source, and instead, sit on top of a overhead projector (OHP). Although panels are light (5-8LB.), even on specially designed, extremely bright, overhead projectors, they produce dim images useable only in darkened rooms on small screens.

Panels survive as the entry level products in every catagory. Typically the most expensive panel in a given resolution, sells for less than the least expensive projector. More expensive panels sell moderately well in SVGA and XGA resolutions due to the tremendous difference in prices between panels and projectors in those resolutions.

A common type of flat panel display consisting of a grid of horizontal and vertical wires. At the intersection of each grid is an LCD (Liquid Crystal Display) element which constitutes a single pixel, either letting light through or blocking it.A higher quality and more expensive type of display, called an active matrix display, uses a transistor to control each pixel. In the mid 1990"s, it appeared that passive matrix displays would eventually become extinct due to the higher quality of active matrix displays. However, the high cost of producing active matrix displays and new technologies such as DSTN, CSTN and HPA that improve passive matrix displays, have caused passive matrix displays to make a surprising comeback.

The original LCDs, these are controlled by a single processing system, for the whole screen, unlike active and poly-si, which have descrete circuits for each "pixel." This results in a panel with terrible color dynamics and contrast (typically 15:1). They are also incredibly slow: On passive laptop computers, the cursor (or anything else) moving on the screen, goes invisible until you stop moving it (submarining) Only one or two projectors use any type of passive matrix display.

Color systems use a red, green and blue dot per pixel, each of which is energized to different intensities, creating a range of colors perceived as the mixture of these dots. Black is all three dots dark, white is all dots light.

Picture element (see Dot/Pixel). Pixels are tiny picture elements comprised of three subpixels (one red, one green, and one blue.) Although a single pixel displays one color, collectively those pixels create a complete image recognizable by the human eye. A single LCD consists of thousands, even millions of pixels.

A pixel anomaly is a pixel that displays only one color (white, black, red, green, or blue.) These are commonly referred to as "stuck" or "void" pixels. If a pixel on an LCD appears to be stuck on one color, it will sometimes come back to life by gently massaging the pixel and the area surrounding it in a circular pattern. (For obvious reasons, pixel massage will not work on a CRT.) A small number of pixel anomalies are considered normal, or at least inevitable, on LCDs. The number of pixel anomalies it takes for a display to be considered defective varies by hardware manufacturer.

A light filter which only allows light waves of a certain rotation through. Polarized material with perpendicular filtering is used in LCDs to enclose the liquid crystal. The liquid crystal is then used as the medium which twists the light waves 90� in order to allow the light to pass through or not.

Are made of a polymer acetate with iodide molecules incorporated in the material. The molecules are arranged to only allow scattered light to enter in one plane/axis. Twisted nematic LCDs require two polarizers, one on the front and one on the back.

The "hot" LCD technology for the top of the line LCD projectors. Poly-Sci is typically 3 separate layers of LCDs, one each for Red, Green and Blue. This results in increased color dynamics, with contrast ratios around 200:1. Poli-Si technology is also a bit faster than the Active Matrix TFT, for smooth video and multimedia.

Active elements, when energized, appear dark in color against a light background (non-energized); i.e., reflective, transflective, transmissive, (positive) inverse image.

A thin (100 microns thick) piece of material laminated to the rear polarizer. Function is to change normal blue colored dots to black. Used on supertwist graphic modules with a CFL light source. Commonly referred to as black and white.

Typically a smooth silver/gray piece of polished aluminum foil bonded to the rear polarizer. Reflects the incoming ambient light. Note: Backlighting can not be used with a reflective type LCD.

Applicable to CRTs but not LCDs, refresh rate equals the number of times per second that the electron gun redraws the image on the screen. For example, if a CRT"s refresh rate is set to 60 Hz, the screen image will be redrawn 60 times a second. Low refresh rates will cause the image to flicker, resulting in eye strain or other problems. For this reason, refresh rates on CRTs should be set as high as possible

This figure indicates how quickly an LCD panel can display a change in the brightness of the screen image. It is calculated as the sum of the times needed for the image to change from 10% to 90% of its maximum brightness, and from 90% to 10%. Faster response times allow a smoother display of rapidly-changing screen images, such as real-time video.

LCD driver or controller electronics are encapsulated in a thin, hard bubble package, of which the drive leads extend from the bubble package on a thin plastic substrate. The adhesive along the edges is used to attach the TAB to the LCD glass and/or PCB.

Definition 1:Abbreviation of thin film transistor, a type of LCD (Liquid Crystal Display) flat panel display screen, in which each pixel is controlled by, from one to four transistors. The TFT technology provides the best resolution of all the flat penal techniques, but it is also the most expensive. TFT screens are sometimes called active matrix LCDs.Definition 2:This term typically refers to active matrix screens on laptop computers. Active matrix LCD (Liquid Crystal Display) provides a sharper screen display and broader viewing angle than passive matrix screens.

There are two primary technologies used for touch screens and both use a clear glass panel overlaid onto the CRT or LCD screen. The resistive method is completely pressure sensitive. It uses a plastic layer on top of a metallic-coated glass layer, separated by spacers. When pressed, it shunts the current in the glass panel, and the x-y coordinates pick up the location on the screen.

The capacitive method uses a metallic coated glass panel, but without the plastic overlay. It senses the change in current from the charge in the your finger or a stylus. The stylus used with this technique must emit a charge and is thus wired to the computer.

A type of LCD which does not have a reflector or transflector laminated to the rear polarizer. A backlight must be used with this type of LCD configuration. Most common is transmissive negative image.

Today VGA resolution normally refers to a 640 x 480 pixel display, regardless of the number of colors available. Originally VGA was 640 x 480 16 colors. Throughout this website it will refer to 640 x480 resolution.

CRT image size is advertised as the diagonal measure of the glass in the display (15", 17", etc.) However, the viewable area, or the size of the image a monitor can actually display, is usually one to two inches less than the advertised size. LCD image size is usually identical to what is advertised, as the physical picture tube border present on CRTs (the space between the viewable area on the CRT and the plastic chassis) is not present on LCD displays.

The dimensions measured from the inside perimeter of the LCD bezel or LCD glass epoxy seal. The viewing area defines actual area that can be illuminated when the entire screen is turned ON (white).

Same as- Elastomer Connector which is a strip of silicone rubber made up of sequentially spaced conductive and non-conductive material. This is the most common connection method for LCD modules.

Let us start with the basics first; refresh the knowledge about TN and LCD displays in general, later we will talk about TFTs (Thin Film Transistors), how they differ from regular monochrome LCD displays. Then we will go on to the ghosting effect, so we will not only discuss the technology behind the construction of the TFT, but also some phenomena, like the ghosting effect, or grayscale inversion, that are important to understand when using an LCD TFT display.

Next, we will look at different technologies of the TFT LCD displays like TN, IPS, VA, and of course about transmissive and transflective LCD displays, because TFT displays also can be transmissive and transflective. In the last part we will talk about backlight.

Let us start with a short review of the most basic liquid crystal cell, which is the TN (twisted nematic) display. On the picture above, we can see that the light can be transmit through the cell or blocked by the liquid crystal cell using voltage. If you want to learn more about monochrome LCD displays and the basics of LCD displays, follow this link.

What is a TFT LCD display and how it is different from a monochrome LCD display? TFT is called an active display. Active, means we have one or more transistors in every cell, in every pixel and in every subpixel. TFT stands for Thin Film Transistor, transistors that are very small and very thin and are built into the pixel, so they are not somewhere outside in a controller, but they are in the pixel itself. For example, in a 55-inch TV set, the TFT display contains millions of transistors in the pixels. We do not see them, because they are very small and hidden, if we zoom in, however, we can see them in every corner of each pixel, like on the picture below.

On the picture above we can see subpixels, that are basic RGB (Red, Green, Blue) colors and a black part, with the transistors and electronic circuits. We just need to know that we have pixels, and subpixels, and each subpixel has transistors. This makes the display active, and thus is called  the TFT display. TFT displays are usually color displays, but there are also monochrome TFT displays, that are active, and have transistors, but have no colors. The colors in the TFT LCD display are typically added by color filters on each subpixel. Usually the filters are RGB, but we also have RGBW (Red, Green, Blue, White) LCD displays with added subpixels without the filter (White) to make the display brighter.

What is interesting, the white part of the RGB and RGBW screen will look exactly the same from a distance, because the lights are mixed and generate white light, but when we come closer to the screen, we will not see white light at all.

Going a little bit deeper, into the TFT cell, there is a part inside well known to us from the monochrome LCD display Riverdi University lecture. We have a cell, liquid crystal, polarizers, an ITO (Indium Tin Oxide) layer for the electrodes, and additionally an electronic circuit. Usually, the electronic circuit consists of one transistor and some capacitors to sustain the pixel state when we switch the pixel OFF and ON. In a TFT LCD display the pixels are much more complicated because apart from building the liquid crystal part, we also need to build an electronic part.

That is why TFT LCD display technologies are very expensive to manufacture. If you are familiar with electronics, you know that the transistor is a kind of switch, and it allows us to switch the pixel ON and OFF. Because it is built into the pixel itself, it can be done very quickly and be very well controlled. We can control the exact state of every pixel not only the ON and OFF states, but also all the states in between. We can switch the light of the cells ON and OFF in several steps. Usually for TFT LCD displays it will be 8-bit steps per color, so we have 256 steps of brightness for every color, and every subpixel. Because we have three subpixels, we have a 24-bit color range, that means over 16 million combinations, we can, at least theoretically, show on our TFT LCD display over 16 million distinct colors using RGB pixels.

Now that we know how the TFT LCD display works, we can now learn some practical things one of which is LCD TFT ghosting. We know how the image is created, but what happens when we have the image on the screen for a prolonged time, and how to prevent it. In LCD displays we have something called LCD ghosting. We do not see it very often, but in some displays this phenomenon still exists.

Another issue present in TFT displays, especially TN LCD displays, is grayscale inversion. This is a phenomenon that changes the colors of the screen according to the viewing angle, and it is only one-sided. When buying a TFT LCD display, first we need to check what kind of technology it is. If it is an IPS display, like the Riverdi IPS display line, then we do not need to worry about the grayscale inversion because all the viewing angles will be the same and all of them will be very high, like 80, 85, or 89 degrees. But if you buy a more common or older display technology type, like the TN (twisted nematic) display, you need to think where it will be used, because one viewing angle will be out. It may be sometimes confusing, and you need to be careful as most factories define viewing direction of the screen and mistake this with the greyscale inversion side.

On the picture above, you can see further explanation of the grayscale inversion from Wikipedia. It says that some early panels and also nowadays TN displays, have grayscale inversion not necessary up-down, but it can be any angle, you need to check in the datasheet. The reason technologies like IPS (In-Plane Switching), used in the latest Riverdi displays, or VA, were developed, was to avoid this phenomenon. Also, we do not want to brag, but the Wikipedia definition references our website.

We know already that TN (twisted nematic) displays, suffer from grayscale inversion, which means the display has one viewing side, where the image color suddenly changes. It is tricky, and you need to be careful. On the picture above there is a part of the LCD TFT specification of a TN (twisted nematic) display, that has grayscale inversion, and if we go to this table, we can see the viewing angles. They are defined at 70, 70, 60 and 70 degrees, that is the maximum viewing angle, at which the user can see the image. Normally we may think that 70 degrees is better, so we will choose left and right side to be 70 degrees, and then up and down, and if we do not know the grayscale inversion phenomena, we may put our user on the bottom side which is also 70 degrees. The viewing direction will be then like a 6 o’clock direction, so we call it a 6 o’clock display. But you need to be careful! Looking at the specification, we can see that this display was defined as a 12 o’clock display, so it is best for it to be seen from a 12 o’clock direction. But we can find that the 12 o’clock has a lower viewing angle – 60 degrees. What does it mean? It means that on this side there will be no grayscale inversion. If we go to 40, 50, 60 degrees and even a little bit more, probably we will still see the image properly. Maybe with lower contrast, but the colors will not change. If we go from the bottom, from a 6 o’clock direction where we have the grayscale inversion, after 70 degrees or lower we will see a sudden color change, and of course this is something we want to avoid.

We will talk now about the other TFT technologies, that allow us to have wider viewing angles and more vivid colors. The most basic technology for monochrome and TFT LCD displays is twisted nematic (TN). As we already know, this kind of displays have a problem with grayscale inversion. On one side we have a higher retardation and will not get a clear image. That is why we have other technologies like VA (Vertical Alignment), where the liquid crystal is differently organized, and another variation of the TFT technology – IPS which is In-Plane Switching. The VA and IPS LCD displays do not have a problem with the viewing angles, you can see a clear image from all sides.

Apart from the different organization of the liquid crystals, we also organize subpixels a little bit differently in a VA and IPS LCD displays. When we look closer at the TN display, we will just see the subpixels with color filters. If we look at the VA or IPS display they will have subpixels of subpixels. The subpixels are divided into smaller parts. In this way we can achieve even wider viewing angles and better colors for the user, but of course, it is more complicated and more expensive to do.

The picture above presents the TN display and grayscale inversion. For IPS or VA technology there is no such effect. The picture will be the same from all the sides we look so these technologies are popular where we need wide viewing angles, and TN is popular where we don’t need that, like in monitors. Other advantages of IPS LCD displays are they give accurate colors, and wide viewing angles. What is also important in practice, in our projects, is that the IPS LCD displays are less susceptible to mechanical force. When we apply mechanical force to the screen, and have an optically bonded touch screen, we push the display as well as squeeze the cells. When we have a TN display, every push on the cell changes the image suddenly, with the IPS LCD displays with in-plane switching, different liquid crystals organization, this effect is lesser. It is not completely removed but it is much less distinct. That is another reason IPS displays are very popular for smartphones, tablets, when we have the touchscreens usually optically bonded.

If we wanted to talk about disadvantages, there is a question mark over it, as some of them may be true, some of them do not rely on real cases, what kind of display, what kind of technology is it. Sometimes the IPS displays can have higher power consumption than others, in many cases however, not. They can be more expensive, but not necessarily. The new IPS panels can cost like TN panels, but IPS panels definitely have a longer response time. Again, it is not a rule, you can make IPS panels that are very fast, faster than TN panels, but if you want the fastest possible display, probably the TN panel will be the fastest. That is why the TN technology is still popular on the gaming market. Of course, you can find a lot of discussions on the internet, which technology is better, but it really depends on what you want to achieve.

Now, let us look at the backlight types. As we see here, on the picture above, we have four distinct types of backlight possible. The most common, 95 or 99 per cent of the TFT LCD displays on the market are the transmissive LCD display type, where we need the backlight from the back. If you remember from our Monochrome LCD Displays lecture, for transmissive LCD displays you need the backlight to be always on. If you switch the backlight off, you will not see anything. The same as for monochrome LCD displays, but less popular for TFT displays, we have the transflective LCD display type. They are not popular because usually for transflective TFT displays, the colors lack in brightness, and the displays are not very practical to use. You can see the screen, but the application is limited. Some transflective LCD displays are used by military, in applications where power consumption is paramount; where you can switch the backlight off and you agree to have lower image quality but still see the image. Power consumption and saving energy is most important in some kind of applications and you can use transflective LCD displays there. The reflective type of LCD displays are almost never used in TFT. There is one technology called Low Power Reflective Displays (LPRD) that is used in TFT but it is not popular. Lastly, we have a variation of reflective displays with frontlight, where we add frontlight to the reflective display and have the image even without external light.

Just a few words about Low Power Reflective Displays (LPRD). This kind of display uses environmental light, ambient light to reflect, and produce some colors. The colors are not perfect, not perfectly clear, but this technology is becoming increasingly popular because it allows to have color displays in battery powered applications. For example, a smartwatch would be a case for that technology, or an electrical bike or scooter, where we can not only have a standard monochrome LCD display but also a TFT LCD color display without the backlight; we can see the image even in

strong sunlight and not need backlight at all. So, this kind of TFL LCD display technology is getting more and more popular when we have outdoor LCD displays and need a low power consumption.

On the picture above, we have some examples of how transmissive and reflective LCD displays work in the sunlight. If we have a simple image, like a black and white pattern, then on a transmissive LCD display, even with 1000 candela brightness, the image probably will be lower quality than for a reflective LCD display; if we have sunlight, we have very strong light reflections on the surface of the screen. We have talked about contrast in more detail in the lecture Sunlight Readable Displays. So, reflective LCD displays are a better solution for outdoor applications than transmissive LCD displays, where you need a really strong backlight, 1000 candela or more, to be really seen outdoors.

To show you how the backlight of LCD displays is built, we took the picture above. You can see the edge backlight there, where we have LEDs here on the small PCB on the edge, and we have a diffuser that distributes the light to the whole surface of LCD screen.

In addition to the backlight, we have something that is called a frontlight. It is similar to backlight, it also uses the LEDs to put the light into it, but the frontlight needs to be transparent as we have the display behind. On the example on the picture above we can see an e-paper display. The e-paper display is also a TFT display variation, but it is not LCD (liquid crystal), it is a different technology, but the back of the display is the same and it is reflective. The example you see is the Kindle 4 eBook reader. It uses an e-paper display and a frontlight as well, so you can read eBooks even during the night.

WF0283ATDAJDNN0 is a 2.83 inch portrait mode Transflective TFT-LCD display module, made of resolution 240x320 pixels. WF0283A module built in with HX8367-A driver IC, it supports MCU/SPI/RGB interface; View Direction 3 o"clock, Gray Scale Inversion Direction 9 o"clock, Aspect Ratio 3:4, brightness 500 nits (typical value), Glare surface panel. This TFT module can be operating at temperatures from -20℃ to +70℃; its storage temperatures range from -30℃ to +80℃.

WF0283A is a Transflective TFT-LCD display; it is characterized by very good readability in bright environments and direct sunlight. Transflective TFT display featured a transparent reflector in front of the backlight. The incoming light is reflected and used to illuminate the TFT display. Therefore, the readability of the content in very bright light is perfect even without any backlight. Customers using a transflective TFT module can save power by reducing or turning off the display’s backlight during bright environments.

WF24LTYAJDNN0 is a 2.4 inch IPS TFT-LCD display module; made of resolution 240 x 320 pixels. WF24L module built in with ILI9341V controller IC, it supports MCU8080 and SPI interface, it featured with IPS panel which is having the advantages of wider viewing angle of Left:80 / Right:80 / Up:80 / Down:80 degree (typical), contrast ratio 800 (typical value), brightness 500 nits (typical value), Glare surface panel. WF24L is having Resistive Touch Panel (RTP) available for option.

This 2.4 inch TFT- LCD display is portrait mode; it integrated controller IC ILI9341V on module, Supply Voltage for Analog (VCI) from 2.5V to 3.3V. This TFT module can be operating at temperatures from -20℃ to +70℃; its storage temperatures range from -30 to +80 ℃.

Winstar OLED WEF012864H is made of 128x64 pixels, diagonal size 2.42 inch. This graphic display is built-in SSD1309ZC controller IC and it communicates via 6800/8080 8-bit parallel, I2C and 4-wire serial interface. WEF012864H is having the same OLED panel as existing WEO012864G and featured with a bezel (frame) on module. WEF012864H is using a low resistance OLED Panel, and the FPC pin assignment has been defined as the same as WEF012864Q (30 pins).

The new version thin 0.91" WEO012832D is also built-in SSD1306BZ driver IC; it communicates via 4-wire serial SPI interface only. WEO012832D OLED module can be operating at temperatures from -40℃ to +80℃; its storage temperatures range from -40℃ to +85℃. Adopting thinner OLED panel is a market trend; please adopt the thinner one for new design projects. If customers would like to use the new thinner one to replace the existing one, please contact Winstar sales reps for more details.

“I use a 32-inch LCD TV for my home office display, connected to my PC using HDMI. I also use it for my PS3 and Wii to prevent a Shining ‘all work and no play’-type incident, so it gets quite a lot of use every day. I left town over the weekend and unthinkingly left a fixed image on the display. When I got back, I found that the image had burned in. I thought LCD displays wouldn’t do that, but I was clearly mistaken. The ocean image that was displayed left shadows of the waves across the display. Is there a way to get rid of this problem, or at least minimize it?”

It was a widespread myth for a while that transmissive displays like LCDs weren’t subject to image persistence (a.k.a. burn-in), but it is more accurate to say that they are less subject to burn-in than phosphor-based displays such as CRTs and color plasma. The good news is that on an LCD it can usually be reversed but on a CRT it is usually permanent.

To start, power-down your display for at least 48 hours. If the image is still persistent, try this tip from Lifehacker, which involves using an all-white screen to overwrite the first burn. You could also display static on your screen instead, or make a screensaver that alternates between black and white images.

The theory here is that the rapidly cycling white/black essentially resets the offending parts of the display with stuck pixels. It may take a long time—perhaps a few days—to fade the persistent image away, but it should improve. However, please note that this is not a guaranteed fix.