Display Technologies Demystified

Display Technologies Demystified:

Display screens have invaded our lives & become ubiquitous in our worlds in all forms and sizes right from something as small as a digital (LCD) watch to something as big as a billboard.

display_devices

The evolution of flat screens and intense competition between major players have led to a slew of technologies like LCD, LED and more. The application & impact has been quite significant in the smartphone industry where advertisements bombard potential customers with acronyms like TFT, IPS, OLED, AMOLED along with marketing terms like Retina, Super clear, PenTile and resolutions like HD, Full HD, qHD, WVGA etc, leaving an uninformed customer utterly clueless and confused.

One can always read 1-2 line definitions of each technology and feel “equipped” while choosing a smartphone but as most of us would agree, half-knowledge is more dangerous than no-knowledge and hence the best approach would be to really understand the science behind these technologies.

salesman

This series of articles is an attempt to explain these display technologies using simple & practical analogies to help the reader understand the underlying concepts so that he/she can take better decisions in future. i.e Having a solid foundation of anything always helps in understanding one’s own requirement and hence choose the right technology product offering and avoid falling for any marketing propaganda. There is really no pre-requisite necessary here because all the explanations are simple, informal & can be understood even by a high school student.

Necessity is the mother of invention. I am always of the opinion that one can understand and appreciate something by going back in time and finding out how a problem had led to application of an invention, leading to its solution & evolution over time. So, here we begin with the display technologies.
america_early_20_centuryRewind back to the early 20th century America. Motor cars had become mainstream, citizens were on a spending spree & business was booming but at the same time, competition was thriving. One of the ways for a B2C business entity like a restaurant, pub, showroom etc to out-compete its rivals was through marketing and what better way than to present itself attractively to a customer? A restaurant on a highway with attractive signboards illuminated during night would make its presence felt and rake in all the cash. But how does one come up with such attractive signboards? This is where Edison’s 1878 invention came to the rescue.

edison_bulb

Incandescent bulbs had become mainstream by the early 20th century and one enthusiastic restaurant owner thought of experimenting with several such light bulbs by aligning them in the form of beautiful illuminated signboard and placed it in front of the restaurant. Bingo. That evening, they witnessed 200% increase in customers and this marketing technique went viral. Within few years, almost all the business outlets in America installed customized illuminated signboards.

light_bulb_boards

Over time, neon lights were also added for more decoration and some of the enterprising engineers even designed programmable display boards using vacuum tubes in which different sets of bulbs (or neon tubes) would glow at different times in a pre-determined pattern to give it some sort of video/animation effect. Those were some of the earliest “programmed” digital display technologies.

skipping_girl

Skipping Girl animated signboard built during 1930s.

In the mid 20th century, some of the most talented engineers in the world came together to build the world’s first computer (ENIAC) and guess what was the display used for this computer? Just a bunch of bulbs!! Everytime after intensively processing for several minutes, ENIAC would finally display the result by lighting specific bulbs corresponding to certain digits.

eniac_excerpt

ENIAC_bulbs

It was one of the earliest known “Matrix Displays”.
Now, what is a matrix?
It is a collection of elements arranged in the form of rows & columns. The advantage of having it in matrix form is that each element can easily be addressed using row & column number. In fact, this concept is used in townplanning as well where each layout or block is like a matrix having several mains (columns) & crosses (rows).

layout_map

Postal department uses the concept of main & cross to locate an address and is called “addressing mechanism”. In display technology also, each element can be accessed using the row & column number because a picture is also no different from a layout and is made up of several elements arranged in rows & columns and each such element is called a “picture element” or “picture cell”. Over time, scientists & engineers shortened the term “picture cell” to “pic cell” which eventually was shortened to “pixel”.

bird_megapixel_zoom

Each picture is made of several pixels.

Hence, pixel can be defined as the most basic (and smallest) element in a picture (or display screen). In print industry, every picture has certain dimension in the form of width by height. For example, a photographic print can have 6 inch by 4 inch dimension. Similarly, a digital picture also must have some dimension and this is represented by “resolution” of the picture which is basically the number of rows of the pixels and number of columns of the pixels. So, when somebody says a picture’s resolution is 1024 by 768, it means that picture has 1024 columns & 768 rows of pixels.

Coming back to our ENIAC which had a bunch of bulbs for display, since each bulb was the smallest element of its display, we can say that 1 bulb of ENIAC was 1 pixel. Since it had a matrix display of 10 by 10 bulbs (pixels), its resolution was 10×10.

These concepts of “Matrix Display”, “Pixel” & “Resolution” became the foundation over which future technologies like LCD were developed.

In the next part, we shall find out how digital displays evolved in 1960s.

UPDATE:
Next part:
http://guruprasad.net/posts/display-technologies-demystified-led-calculators-led-watches/

To receive updates & notifications of subsequent parts of this series, subscribe to the portal by entering your email ID and confirming it from your inbox.

  • Enter your email id

, ,