Almost every single human in the world carries a display that is embedded into such a device called a cellphone or smartphone at this very moment. However, we might have no idea what type of display that is and how the mechanism works behind it. In this article, we are trying to bring the best information about display technology.
What is Display?
A display is an electronic device whose main purpose is an interface to show the reading (information) as the result of a certain process of a computer or electronic circuit. The information could be a text, picture, or video which is a sequence of pictures.
How Does It Work?
The working mechanisms behind the display are different from one another. They all depend on the display types. Even though, they have the same functionality. The engineering methods vary with each type of display. A more detailed mechanism will be explained in the display types section.
The Display Evolution
Every complex thing always starts with simplicity. It all started in the 1920s. The CRT (Cathode Ray Tubes) display was initially used for oscilloscopes. Over the years, then it was developed for tv monitors and computers lastly. In 1934, the German company of Telefunken produced the first commercial CRT TV. The simple TV became the mainstream commercial color CRT produced by Radio Corporation of America (RCA). In the 1970s, Wolfgang Helfridge, a physicist of RCA had the idea to make an electronic display based on the twisted nematic effect phenomena. The first wristwatch called the Gruen Teletime was released featuring the LCD technology in 1972.
Matrix displays were first introduced in the 1990s. The basic principle was to make the LED (Light Emitting Diode) by giving a certain amount of electrical current onto it. On its development, OLED (Organic LED) was then introduced by using the carbon-based molecules to gain that similar effect. The concept of pixels was basically the millions of carbon-based molecules grouped together, formed such a screen, and called a modern OLED screen. Later on, the AMOLED (Active Matrix) display was introduced after the new mechanism of how the LED driver can control one-row pixels at a time at such a rapid speed.
Here comes the most modern type of display that is the multi-touch display. The first introduced was the resistive touch display. In the early 2000s, FingerWorks the multitouch technology developed devices that were mainly aimed at those with wrist injuries and disabilities. The FingerWorks company was later bought by Apple because of its employee who brought the multi-touch device when he was wrist-injured. This technology then became the one that was used by the iPhone in 2007.
The Display Types
You may get the idea of how the display evolution is over the years since its first invention. In this section, the explanation will be based on the display types.
1. Cathode Ray Tubes (CRT)
This type of display has a big size, heavy, and bulky dimension. There is a reason why it is. It consists of the electron gun that works by horizontally beam-firing row by row the electrons into millions of really small red, green, and blue phosphor-coated dots arrays. Eventually, when the beam hit the tiny phosphor dots. They will glow and the illusion of moving pictures can be formed over the rapid beam exposure.
The CRT screen was still the first choice and owned in the 20th era despite being a heavy and bulky dimension.
2. Liquid Crystal Display (LCD)
The working mechanism it has is called the twisted nematic effect principle. The special liquid crystal molecules could be aligned depending on two states (Voltage off and voltage on) by the electric field.
The off-state is when the molecules are twisted and not aligned. In that state, there is no voltage applied to the molecules. On the other side, if the low voltage is applied to the molecules, then it will align the molecules. Basic numbers and letters, later on, can be formed by manipulating this effect. At the time, typical displays required 40v or more to run. However, the LCD types used really low power and became the best for wristwatches and pocket calculators till modern LCDs nowadays.
If you are having a project and looking to consider which LCD best suit your project, you may want to watch the following great video.
3. Matrix Display
It is also known as the LED display of how common people call it. The mechanism used is the same as the twisted pneumatic effect. However, it is applied on a larger scale and different object that is LED in millions of pixel form. The OLED is based on carbon-based molecules using the said similar method.
A question arises of how to manage millions of pixels in a screen. The answer is the transistor as it turns out. The three tiny transistors will control the sub-pixels (red, green, and blue) of each pixel. By controlling it means that the transistors will vary the brightness level of each sub-pixels to represent a single color. The combination of these will make an image. The AMOLED (Active Matrix OLED) display has the mechanism of the rapid speed of how the LED driver (transistors) can control one row at a time.
4. Multi-touch Display
It can be divided into a resistive and capacitive touch display. The resistive touch display technology is the display in which you need to use force in order to get recognized such as ATM screens and early PDAs (Personal Digital Assistant) back then. It made the community pretty skeptical and became hard to use.
On the other side, the capacitive-touch display utilizes the human fingers as the electric conductor. The electrostatic will undergo a change when the fingers touch the screen surface without a force. The change in electrostatic then can be measured and produce more accuracy than the resistive-touch display mechanism.
The Display Specifications
This section gives the common specifications about the available modern displays nowadays. Regardless of your occupation, we wish this section will enrich your knowledge more about the display. Below are the specifications of the displays:
It determines the total number of pixels on the screen. The most common is 1920×1080 that is FullHD or 1080p. On its development, more resolution is introduced such as 2K, 1440p, 4K, even 5K and 8K for professionals.
This is often explained in inch size. Most people use the 22-inch type. The size is measured diagonally just for your information. To keep the image quality sharp and clear, a bigger size display may need a bigger resolution.
3. Aspect Ratio
This is to represent the width to the height. It can be measured from the resolution too. The common aspect ratios are:
- Wide – 16:9
- UltraWide – 21:9
- SuperWide – 32:9
4. Panel Type
This is for the LCD types because they have been longer around than OLED. The types are as the followings:
- TN – Twisted Nematic
- IPS – In-Plane Switching
- VA – Vertical Alignment
5. Refresh Rate
It represents how often a display can update per second (Hertz or Hz). The common refresh rates are 60Hz, 75Hz, 90Hz, 120Hz-Gaming, and 144Hz-Gaming.
6. Response Time
It refers to the time needed for the display to change its color and measured in milliseconds.
7. Synchronization Technology
There are two common types which are:
- G-Sync – the adaptive sync technology developed by Nvidia
- FreeSync – developed by AMD
8. Viewing Angles
It is measured by two numbers such as 160/120 where 160 is the horizontal viewing angle and 120 is the vertical viewing angle. As long as you are in 160 out of 180 degrees horizontally and 120 out 180 degrees, you will still get a clear view.
9. Input Connectors
There are some you may need to know. Those are:
- VGA – Video Graphics Array
- DVI – Digital Visual Interface
- HDMI – High Definition Multimedia Interface
- DisplayPort – developed by PC makers to replace VGA and DVI
- Thunderbolt – developed by Intel and Apple. Thunderbolt 1 and 2 use MiniDisplayPort while Thunderbolt 3 uses USB-C.
It is indicated commonly in the range from 1800R to 4000R. The smaller curvature rating means a more aggressive curvature.
The units used are nits or cd/m2. The adequate standard is about 200-300 nits.
It stands for High Dynamic Range. It is similar to contrast ratio and brightness. If a display is HDR-certified then it means that it is capable of high brightness and contrast which result in the brightest parts and darkest parts of an image.
It refers to a measure of the luminance between the darkest black colors and the brightest white a display can produce. For example, a display with a 1000:1 contrast ratio. The higher contrast is determined by the higher the first number.
14. Color Space
It defines the capability to display the colors. The standards are DCI-P3, sRGB, and Adobe RGB.
15. Color Accuracy
It defines how well the display is capable to produce colors and shades as supposed.
You have an idea of what the display is now. When it comes to digital measuring instruments, the display is one of the most important body parts. It shows the measurement readout and you can take it instantly.
In addition, when it comes to electronic measuring instruments, the display is one important thing to learn besides the microcontroller, ADC, DAC, communication data, power supply, etc. There are three options mentioned we think will suit your project: LCD, Matrix, and Multitouch display. Herewith, this post may give you a little idea of which display between those three display that is ideal for your project.