OLED and AMOLED
LCD and Plasma technologies represent a milestone for the screen industry, but they are not alone. More recently, OLED (Organic Light Emitting Diode) and AMOLED (Active Matrix OLED) technologies have started to have a place in this segment. See abbreviationfinder for more acronyms other than OLED.
Before proceeding, it is important to note that many devices have LCD screens with LED backlighting (while others do it with special lamps). This means that the panel has a set of LEDs responsible for illuminating each section of the LCD. With that, the manufacturer promotes the device as an “LED monitor” or an “LED TV”, but it is important to make it clear that these devices are not OLED or AMOLED.
In time, LED (Light Emitting Diode) consists, as the name implies, of a diode (semiconductor material) capable of emitting light when energized. It is a component widely used by the industry because it is cheap and more durable. You can find it in electronics of the most varied types, even in car headlights.
OLED has a certain resemblance to LED, but it differs in its composition: it is a material formed by organic diodes (that is, constituted with carbon) that generate light when they receive electric charge. These diodes can be quite small, allowing each pixel on the screen to receive this material in order to be illuminated individually.
As the OLED is capable of generating light, the screen does not need a backlight. Because of this, the industry can create thinner screens that generate less manufacturing costs, as this process is also simpler. The thickness of OLED panels is so minuscule that it is even possible to manufacture flexible screens, which are already being tested by several manufacturers.
The advantages do not end there: OLED screens also use less energy; they generate sharper colors, including black, since there are no layers that can decrease the intensity of illumination; support greater viewing angle; and offer less response time.
Because of this, OLED screens are used mainly in mobile devices, which need thinner screens because of their small size and also with less energy consumption, since they are only connected to the sockets for recharging the battery.
There is a variation of OLED called AMOLED. The main difference between both is that screens composed with this latest technology are of the active matrix type. It is similar to the situation on the LCD: OLED screens with passive matrix are oriented with a scheme of transistors organized in rows and columns; on AMOLED screens, transistors are applied considering each pixel.
To make this possible, AMOLED screens, like the LCD, also use a TFT layer, which makes their manufacture a little more complex. However, several advantages arise from this process, such as screens with even shorter response times and more vivid colors.
More variations of OLED technology can be found. One, presented by Samsung, is called by the company Super AMOLED . Its development is the result of companies’ dispute for the manufacture of the finest screen: the “common” AMOLED is essentially composed of layers with cathode, organic material and TFT inserted between glass sheets. In Super AMOLED, one of these blades is eliminated, as well as the space between layers is reduced, allowing the formation of a thinner screen.
Super AMOLED screens are able to alleviate an AMOLED problem, since it also has less reflective material: the difficulty of viewing the screen in situations of exposure to sunlight, a problem that also occurs with LCD and Plasma screens, but generally with less intensity. If we take into account that OLED and AMOLED screens are mainly applied to mobile devices, therefore, with more chances of being exposed to the Sun, it is quite an advantage!
Touch screens (touchscreen) exist for some time, but only in recent years become 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 executes certain actions on the screen through touch.
There are several technologies for this type of application, such as screens that use infrared sensors or acoustic waves from surfaces. However, the most common technologies are resistive and capacitive screens.
Resistive screens first hit the market and are used mainly with stylus, although they can also be operated with your fingertips. Its operation occurs, essentially, as follows: the screen has two very thin layers overlapping, with a very small space between them. When a touch is made on the screen, the two blades touch each other at that point, causing a change in the electrical current that passes through there. This change is identified and its coordinates are passed on to the device itself, which will perform the related task.
Resistive screens have simpler fabrication and less costly components, so they are cheaper. On the other hand, they have considerable disadvantages: their blades make the screen darker to begin with; in addition, they may not work very well with touch from your fingertips; finally, applications that require two or more simultaneous taps generally do not work as expected with this type of screen.
Capacitive screens are more sophisticated and, consequently, more expensive, but offer a much better user experience. It is the type of touchscreen found on Apple’s iPhone and iPad lines, for example.
Capacitive screens have a blade that receives an electric charge. When the user touches the screen, the electric charge at the fingertips causes a change in the electric field present there. With this, the device is able to identify the points being touched and perform the necessary action.
Capacitive screens are more advantageous: the user does not necessarily need to exert pressure on the screen, as is the case with resistive screens, with just a touch; it is possible to use multiple simultaneous touches; the canvas has no layers that make it considerably darker.
On the other hand, the user may have some difficulty using the screen if he is wearing gloves, for example. In addition, applications that require a stylus need this device to have at its tip some material capable of altering the electric field of the screen.