Introduction
In a past not very distant, to buy a monitor video or a tv was to purchase a device big and heavy, after all, these devices were of the type CRT (Catodic Ray Tube- cathode ray Tube). Today, however, monitors and televisions take up a lot less space and offer the best picture quality. Two technologies is quite popular in this segment are the screens of LCD (Liquid Crystal Display) and Plasma, which can also be employed in devices portable. As if that weren’t enough, these technologies soon they began to share space with screens OLED (Organic Light-Emitting Diode), and AMOLED (Active Matrix Organic Light-Emitting Diode). But, what do these names mean? What is the difference between LCD and Plasma? OLED screens or AMOLED are better in what? The AbbreviationFinder presents the answers to these and other issues below.
What is the LCD?
The technology LCD (Liquid Crystal Display – Crystal displays Net) is not employed only in the monitors or TVs. In the market, it is possible to find devices – portable as consoles games, mobile phones, calculators and digital cameras – whose screens are also the usage of this technology. Laptops, for example, use this type of screen for years.
As its name indicates, the “secret” of the LCD is in a material called liquid crystal, which receives this name because, although this is not exactly a component net, its characteristics do act as such.
In its constitution more simple, molecules liquid crystal are distributed between two transparent blades polarized called substrates. This process is oriented differently in the two blades, so that these form the axes of polarizers perpendicular, as to form an angle of 90°. The roughly, it is as if a blade were to receive horizontal polarization, and the other, vertical polarization, forming a schema of type “lines and columns”.
The molecules of liquid crystal are able to guide the light. When an image is displayed on an LCD monitor, electrical elements present in the blades generate fields magnetic that induces the liquid crystal to “guide” the light from the light source to form the visual content. Always necessary, a different voltage can be applied, causing the molecules of the liquid crystal if to change so as to prevent the passage of light.
On monochrome screens (common in watches and calculators, for example), the molecules assume two states: transparent (light passes through) and opaque (no light passes). For screens that display colors, different voltages, and filters that work about the white light are applied to the molecules.
Active matrix and passive matrix
The LCD screens are divided, basically, into two categories: active matrix (Active Matrix LCD) and passive matrix (Passive Matrix LCD). The first type has as main difference the application of transistors for each pixel (in a few words, pixel it is a point that represents the lower part of the image on a screen), while that, in the passive matrix, the transistors are applied by taking as the basis of the already mentioned scheme of rows and columns.
With this, on the screens of active matrix, each pixel of this can receive an different voltage, allowing, etc., the use of high resolutions. On the other side, its manufacture is so complex that it is not rare to find monitors new that have pixels that does not work, the so – called “dead pixels”.
The screens over passive matrix, in turn, have the constitution more simple. The liquid crystal it is positioned between two substrates, as shown in the illustration follow. Integrated circuits are in charge of controlling the loads that activate the pixels, allowing images to be formed on the screen.
Due to its simplicity, screens, passive matrix are cheaper, but have drawbacks considerable, such as lower response time (learn what this means later). So, currently, its use is common only on devices that do not require such quality, as calculators. In this sense, more sophisticated equipment are built with active matrix.
The simplicity of the screens over passive matrix resides in the fact that application of voltages considering rows and columns does not have the same level of complexity that the fabrication of screens of active matrix. The problem is that when a pixel is triggered from this schema, the application of tension on it can do with that pixels of the rows and columns surrounding will also be affected, making that work, even slightly, impairing the generation of the image as a whole.
In the active matrix, this problem was solved because the application of a control voltage for individual each pixel does not have the “side effect”, that is, not “contaminate” neighboring pixels. Usually, the screens of active matrix use a component called TFT (Thin Film Transistor – something like Transistor Film Thin), whose main characteristic is precisely the application, by means of a layer of transistors specific to each pixel.
Types of LCD
The search for better images, coupled with the processes viable manufacturing has caused the industry to develop several types of LCD. The following are the varieties most frequently found:
– TN (Twisted Nematic): this is one of the most common types, used in devices of low cost. In it, the particles of in the liquid crystal are positioned in such a warped way. The application of electric charge is able to do the crystals rotate up to 90 degrees, according to the voltage level used, determining the passage or not of light. There is also a type called STN (Super TWisted Nematic) which is a kind of the evolution of TN. Their molecules have handling is improved, making the user to be able to see the image on the monitor satisfactorily at angles many times higher than the 160th, a feature not existing panels to TN. There are still other variations, such as Double Layer STN , and Film-compensated STN;
– IPS (In-Plane Switching): this is a technology more sophisticated, mainly applied in the equipments of LCD larger quality. In it, the particles of liquid crystal are the following a horizontal alignment instead of vertical, as is usually the case with panels TN. Thanks to this, IPS screens are able to work with higher refresh rate (concept addressed more to the front), resulting in more visual comfort to the user. IPS panels also offer more clarity and brightness, in addition to display satisfactory even when the screen is looked at from a point side. There are also a variation called S-IPS (Super IPS), able to work with more angles, resolutions the largest and highest rates of pronounced brightness. As they spend more energy mainly due to the use of larger amounts of transistors -, IPS screens are not often employed in portable devices, such as laptops and tablets;
– AFFS (Advanced Fringe Field Switching): similar to the technology IPS, since that also uses alignment horizontal, the specification AFFS is employed in the equipment that offer high image quality, having as differentials the ability to put in a good display in varying angles of observation and offer excellent color fidelity;
– VA (Vertical Alignment): in this type, the particles of the crystal net are in a vertical position in relation to the substrates. Type screens are able to offer good colour reproduction and viewing from multiple angles, but usually have a response time in levels worst in compared to the IPS and AFFS. As with the other types, screens VA also come with variations, the most common being the MVA (Multi-domain Vertical Alignment) and PVA (Patterned Vertical Alignment);
– ASV (Advanced Super View): this is a technology developed by Sharp that is similar to the VA. According to the company, its the main advantage is support for multiple angles vision, can reach 170 degrees. This is because the the molecules of the liquid crystal can be placed in several directions, with movements similar to those which fireworks are to explode;
– Super PSL (Plane-to-Line Switching): being one of the most recent and having Samsung behind its development, the technology PSL is similar to the standard IPS. However, according to the company, a screen of the type is about 10% brighter and has a cost of manufacturing 15% smaller in comparison to this last. Its application is intended for both for monitors and TV sets and for mobile devices.
What is Plasma?
The LCD technology is certainly a breakthrough for the industry screens (displays), but did not come alone: especially in the segment of televisions, the screens of Plasma respond for a good slice of the market.
In fact, this is not a technology necessarily new: the first screens of the type were presented in the 1960’s. However, the technology has undergone improvements significant in recent years.
As you already know, the main component of the LCD is the liquid crystal present between the two blades. In Plasma, the schema is similar, but the material that remains enters the layers is a type of gas that is stored in a set of millions of cells.
This gas, when stimulated electrically, releases light ultraviolet. This, in turn, cause reaction in the atoms of phosphorus, the lining of each cell. The phosphorus is an element that generates lighting when subjected to other light.
In the panels of Plasma, typically each pixel is formed by three cells, each responsible for a color different: red (red), verde (green), and blue (blue). The combination of these is what generates the colors that we see on the screen. The phosphorus present in each cell it receives an intensity of ultraviolet light is different, allowing millions of combinations that result in the range of colors.
Thanks to this, panels of Plasma are able to have their pixels illuminated individually. The result is a screen with excellent levels of brightness and sharpness, even when viewed from positions further apart in relation to the front of the unit.
Which is better: LCD or Plasma?
Depends. It may seem like an answer too evasive, but it is the most appropriate. Is good to know that each technology has its advantages and disadvantages, and that these can be mitigated or pronounced, depending on the product as a whole.
By default, we can say that the LCD has the following disadvantages: less brightness, doesn’t display the color black “deep” with fidelity, the possibility of one or more pixels do not work correctly (the already mentioned one dead pixel), there may be more limitations in the variety of resolutions available.
Plasma screens, in turn, are susceptible to a problem called burn-in, which consists of marks left on the panel when certain images are displayed for a long time in the device, such as, for example, the logo of a TV station in the corner of the screen. In addition, they are more expensive and, often, more fragile.
But, as you saw in the topic about types of LCD, the the industry works tirelessly on ways to improve the technologies, therefore, not infrequently, the problems associated with the each pattern can be lessened or even eliminated.
For this reason, faced with the dilemma of choosing between a product and an LCD another Plasma, it is certainly more appropriate to observe the specifications for each device. The topic following discusses the most common features.
The characteristics of the screens
In choosing a video monitor or even a TV, independent of technology, it is important to note some aspects to make a good acquisition. The following are the the main features to be observed.
Response time
The response time is an important feature, mainly those who want to use the monitor or the TV for games or high-definition videos. This is because these are apps that require changes fast of visual content. If the monitor or the TV is not able to keep up with these changes, that is, have a response time bad, will cause unwanted effects, how to “phantom objects” in the image or shadow on movements.
The lower the response time, the better the update image. To the current standards, it is recommended that a equipment that have this measure in time of less than 10 ms.
Refresh rate
The update rate (refresh rate) indicates the amount of times the screen is refreshed per second. Your measure it is done in Hertz (Hz). If a monitor works with 75 Hz, for example, this means that the image is refreshed 75 times per second on the screen.
In general terms, the higher the refresh rate, more visual comfort, the user will have, especially in video streams quite busy. The minimum recommended is 60 Hz.
Worth mentioning, however, that this aspect was very important to us devices CRT, since these use a beam of light that sweeps all of the screen. Thus, the higher the refresh rate, but quickly the beam finishes a scan and begins another.
On the screens today, whether they be LCD, Plasma or OLED, the rate of update is not so important thus, since the pixels remain active until a image change make change of condition.
Screen size and resolution
When LCD monitors started to become popular, it was common find screens with size of 14, 15 and 17 inches. Today, the size minimum most common for monitors 19 inch, not being rare monitors with screens 20, 21, 23 or even more inch. The Televisions of the most common vary between 20 and 50 inch, being that Plasma screens are generally applied more commonly in the larger models.
It is also interesting to note that, currently, virtually all monitors and tvs are widescreen. This indicates that your screens are wider, making them a great option for viewing movies or for to view more information on the screen.
As a rule, a monitor can be considered to be widescreen when you have a aspect ratio greater than 4:3. This means that the aspect ratio of the screen is a unit of measure greater in the width for each three units of measurement in height. For the purposes comparative, would show a screen having aspect ratio of 4:4 (or 1:1) to be considered square. The monitor seen below has aspect ratio of 16:9, therefore, is widescreen:
Worth mentioning that if a screen has, for example, the size of 19 inches and widescreen format, it does not mean that the device it is, necessarily, larger than a monitor of 19 “normal”. What happens on wide screens is that, roughly speaking, their the sides are more distant, but the distance between the the upper and lower ends do not increase in the same proportion.
In relation to the resolution, monitors and televisions are currently working with rates that are satisfactory. When we talk about this aspect, we are referring to the set of pixels that form horizontal and vertical lines on the screen. Let’s take as an example a resolution of 1600×900. This value indicates that there is 1600 pixels horizontally and 900 pixels vertically, as exemplifies the image:
Still on the resolution, you can find terms as 720p and 1080p. As explained by this article on HDMI, these classifications indicate the amount of pixels supported by the device, in addition to the use of progressive scan or interlaced scan. In progressive scan, all lines of pixels of the screen are updated simultaneously. In turn, in the mode the interlaced scan, the first lines pairs receive update, and then the odd lines, or is, it is a schema of type “other line”. In general, the mode progressive scan provides better image quality.
Thus, the letter ‘p’ existing in 720p, 1080p and other resolutions indicates that the mode used is progressive scan. If it is used for interlaced scan, the letter used is ‘i’ (for example, 1080i). The number, in turn, indicates the amount of rows of pixels in the vertical. This means that the 1080p resolution, for example, with 1080 lines vertical, and works with progressive scan. Here are some common resolutions:
- 480i = 640×480 pixels with interlaced scan;
- 480p = 640×480 pixels with progressive scan;
- 720i = 1280×720 pixels with interlaced scan;
- 720p = 1280×720 pixels, with progressive scan;
- 1080i = 1920×1080 pixels with interlaced scan;
- 1080p = 1920×1080 pixels with progressive scan.
You must have already heard of the term Full HD (High Definition). This expression, whose interpretation would be something like “High-Definition” the Maximum, it indicates that the screen work in the maximum resolution, that is 1080p. This means that the device will be able to run in the highest quality videos from a disc , Blu-ray, for example – ready for this level of resolution.
Are emerging in the market tv sets more sophisticated able working with 4K, a resolution that is so high that its use is not rare in cinemas. This measure indicates that the the instrument is capable of providing images up to 4096×2160 pixels. Amazing, isn’t it? To get an idea of the the “power” of 4K resolution, a video of a few seconds can require several gigabytes in size to take advantage of all its potential.
It is also possible to find equipment that working with resolutions of 2K (2048×1080 pixels) and 8K(7680×4320 pixels).
You can learn more about resolutions 1080p, 4K and the like here even in the AbbreviationFinder.
Contrast and brightness
The contrast is another important characteristic in the choice monitors and televisions. This is a measurement of the difference of brightness between the white more strong, and the black more the dark. The higher this value is, the more faithful will be the display of the colors of the image. This happens because this rate, when in greater number, it indicates that the screen is able to to represent the differences between colors. To the minimum of fidelity, it is recommended the use of screens with contrast of at least 500:1 or, if the manufacturer states this measure as being “dynamic contrast”, of 10,000:1.
In relation to the brightness, the ideal is the use of the screen that to have this rate in, at least, 250 cd/m2 (candela per meter square).
Angle of view
The easiest way to view the content displayed in the the screen is well ahead of her. But, in the room of a house with several people, for example, someone always you will be in a lateral position in relation to the TV. Therefore, it is important to choose a monitor or a tv with support angles view more “generous”.
The ideal is to choose a device that offers angle of view maximum the nearest possible to 180 degrees. Note that some manufacturers may announce this measure as being, for example, 170H/150V. The letter ‘H’ indicates the angle in the horizontal, while ‘V’ does considering the vertical, that is, the visualization from many degrees up and down.
OLED and AMOLED
The technologies that LCD and Plasma represent a milestone for the industry screens, but they are not alone. More recently, the technology OLED (Organic Light Emitting Diode) and AMOLED (Active Matrix OLED) began to take space in this segment.
Before we proceed, it is important to note that many of the devices they have LCD screens with LED backlight (while others do it with special lamps). This means that the panel has a set of LEDs responsible for illuminating each segment of the LCD. With this, the manufacturer promotes the device with being a “LED monitor” or an “LED TV”, but it is important to let of course, these devices are not OLED or AMOLED.
In time, LED (Light Emitting Diode) consists, as the name indicates, in a diode (semiconductor material) capable of emitting light when energized. This is a component with wide use by the industry for being cheap and more durable. It is possible to find it in electronics of various types,even in flashlights, cars.
OLED
The OLED has a certain similarity with the LED, but differs in its composition: it is a material formed by diodes organic (that is to say, constituted with carbon) generate light when they receive the electric charge. These diodes can be quite small, allowing every pixel of the screen to receive this material to be illuminated individually.
As the OLED is capable of generating light, the screen does not need backlight. Because of this, the industry can create screens thinner and they generate less costs manufacturing, as this process alsoit is more simple. The thickness of OLED panel is so tiny that it is even possible to even the manufacture of flexible fabrics, already in test by several manufacturers.
The advantages don’t end there: OLED screens also spend less energy; generate colors more vivid, including black, since there are no layers that may decrease the intensity of illumination; support larger angle vision; and offer less response time.
Because of this, OLED screens are mainly used in mobile devices that need screens but thinner for because of its small size and also less consumption of energy, since they are only connected to the outlets to recharge the battery.
AMOLED
There is a variation of the OLED display called AMOLED. The the main difference between both is that screens composed with this latest technology are of type active matrix. Is a situation similar to that existing in the LCD: screens OLED display with passive matrix are oriented with a scheme transistors arranged in rows and columns; in AMOLED screens, the transistors are applied by considering each pixel.
For this to be possible, the AMOLED screens, such as LCD, also use a layer of the TFT, which leaves your manufacturing a little more complex. But, this process there are many advantages, such as screens with response time still smaller and more vivid colors.
It is possible to find more variations of OLED technology. One of them, presented by Samsung, is called by the company’s Super AMOLED. Its development is the fruit of the dispute companies for the manufacture of the finer screen: AMOLED “common” is, essentially, composed of layers with the cathode, the organic material and the TFT inserted in between blades of glass. In Super AMOLED, one of these blades is deleted, as well as the space between the layers is decreased, allowing the formation of a the screen more thin.
Screens Super AMOLED can soften a problem of the AMOLED, already that also has the lowest amount of reflective material: the difficulty of viewing the screen in situations of exposure to sunlight, problem that also occurs with LCD screens, and Plasma, but usually with less intensity. If we take into account that OLED screens and AMOLED are applied mainly in devices mobile, therefore, with more chances of being exposed to the Sun, it is an advantage and so much!
Touch screens
Touch screens (touchscreen) there are no times, but only in recent years became popular, especially with the emergence of smartphones and tablets. The idea is very simple: with the use of a special pen (stylus) or with the tips of the fingers, the user performs determinations and actions on the screen by means of taps.
There are several technologies for this type of application, such as the screens that use sensors infrared or acoustic waves from surfaces. In however, the technologies the most common are the screens resistive and capacitive.
Screens resistive
Screens resistive arrived first to the market and are used mainly with a stylus, although they can also be triggered with the tip of the fingers. Your operation is, essentially, the following way: the screen has two blades quite thin overlapping, and there is a very small space between them. When a touch is performed on the screen, the two blades touch at that point, causing a change in the current electrical that goes through there. This change is identified and its coordinates are passed to the the device itself, that will perform the related task.
Screens resistive are manufacturing the most simple and components less costly, therefore, are cheaper. By the other hand, have significant disadvantages: for to start, their blades leave the screen darker; in addition, they may not work very well with touch the from the tip of the fingers; finally, applications that require two or more simultaneous touches that usually do not work as expected with this type of screen.
Screens capacitive
Screens capacitive are more sophisticated and, consequently, more expensive, but offer a much better experience to the user. It is the type of touch screen found in the lines of iPhone and iPad of Apple, for example.
The screens capacitive have a blade that receives load electrical. When the user touches the screen, the load electric existing in the tip of the fingers causes a change in the electric field present there. With so, the device is able to identify the points that are being touched and run the action required.
Screens capacitive are the most advantageous: the user not need, necessarily, exert a pressure on the screen, such as occurs on the screens-resistive, simply by the touch; it is possible to use multiple simultaneous touches; the screen has layers that make it considerably more dark.
On the other hand, the user may have some difficulty to use the screen if you are using gloves, for example. In addition, applications that require a stylus need this the device has at its tip a material able to change the field electric screen.
Screens 3D
Not too long ago, that the example of the theatres, the the industry began to have screens capable of generating images 3D. In a nutshell, this means that a person is able to view certain content on the screen with a depth perception sharp, causing it to have the printing of the image in focus is, indeed, the in front of her.
Type screens are more sophisticated and, consequently, more guys. A good part of them requires the use of special glasses for viewing three-dimensional content, although the market is already count with devices that dispense the use of these devices. An example is console handheld games Nintendo 3DS.
Basically, the 3D content is formed by the simultaneous display of two images the same, but displaced slightly in the horizontal. Each image is captured of an individual way for each eye. This entire process generates the the perception of depth. Note that, with this, people that have a eye committed to end up not been able to “join up” (converge) the images to view the material as being 3D.
In the cinemas, the glasses used are passive. The type of glasses which the most popular is the one that uses a lens in the color blue and the other red in color. The lenses red can you “undo” the tones of this same color from the image. The blue lens does the same with its tones. This scheme is able to generate a sense of depth.
However, it is more common to find in theaters glasses type polarized. These have lenses that filter light to pass the from certain angles. This type of glasses became common because it displays the colors more faithful.
In the case of 3D TVs, it is more common to use active glasses. These are usually formed by lenses that make use of the technology LCD or even Plasma that are transparent and opaque of according to the 3D content displayed, so that the right eye to be without reception of the lights when you images to the eye left are shown, and vice-versa. This happens way extremely fast. In addition, the glasses if communicate with the TV for some wireless technology (usually, infrared or Bluetooth) to “know” the the moment of enabling or disabling the passage of light to each eye.
In the case of equipment that does not require 3D glasses, there are several “tricks” that can be employed, however, it is more common to use screens that have a layer of lenses extremely small, where part of the directs the image to the eye left and the other to the right eye. Such lenses are arranged interleaved. The problem is that the 3D content needs to be available compatible with this scheme for the three-dimensional effect work.
Screens 3D may be offered by the technologies discussed here, being more common, in the case of televisions, LCD panels and Plasma. Note that it is not any equipment of the type that can display three-dimensional images; it is necessary that the device to be prepared for that. In addition, the content – like a movie – also need to be compatible.
Note that the brain ends up having to work more to be able to to focus and converge the images, so, not seldom, a the person may tire more quickly when viewing 3D content.
Gorilla Glass
The technology Gorilla Glass is one of the items that differed the iPhone in your release. It has so much importance to this line that the the history of its use was even told in the biography of Steve Jobs, since the executive was directly involved with its adoption.
Jobs wanted the iPhone screen using glass, instead of the other through the transparent material. The problem is that glass is a component that can suffer scratches or breaks with relative ease. On account of this, went to look for some technology of glass highly scratch-resistant.
Does not take long for Jobs to find Wendell Weeks, who ran the company Corning Class. Jobs explained that the type of glass looking for it and, to his happiness, Weeks revealed that his company has developed a technology in the mid-1960s that could fit your need.
Wendell Weeks was talking about a type of glass made with a process chemical that made him quite tough, therefore, with chances as well smaller to be broken or scratched. The problem is that this type material not found application in market, making the Corning Glass stop producing it.
So it was that the Gorilla Glass appeared as a new technology. Jobs only had to convince Weeks to manufacture the power to the iPhone. In spite of the uncertainties in the leader of Corning Class, the first batch was delivered after six months, approximately.
Currently, it is possible to find the technology Gorilla Glass being used in smartphones, TVs, tablets, and other devices produced by various manufacturers.
As the technology Gorilla Glass is not expensive so significant products, acquire a device that use can really be worth it.
Ending
You saw in the text that the industry has shown tireless in the search for screens that can offer excellent image quality, lower power consumption and reduced costs manufacturing. But, point which technology is the best depends on the circumstances.
So, regardless of what you are thinking of buying, the the ideal is to test, if possible. In a store, you can compare the images of LCD televisions or Plasma specifications like, for example. The same goes for smartphones or tablets – the test screen and note if you can use it without difficulty and if the images are satisfactory to you. In shopping over the Internet, a good the idea is to search for opinions about the product.
