Unique qualities of the device
The plasma TV is still quite commonly used today, and have a large market value. However since their development in the 1960s they are one of the newest forms of TV technology. Over the years since its invention it value have fluctuated due to the other types of TV technology which has been developed such as LED.
This primary factor of this type of television technology is that it can be used for multiple purposes, as it can be cut to a very small sizes (1 inch) for specific applications and made huge too (90 inch). It is this feature of the technology which makes plasma TVs stand out from other TVs in today’s market.
Features & Functionality
The plasma screen is made up from a multitude of little gas pockets (cells) which are placed between two sheets of glass. Each cell reacts like a florescent tube which emits ultraviolet light which then is absorbed by multiple phosphorus coats, which make up each pixel. The brightness is modulated by the amount of UV light emitted from the cell tubes to the coats.
The TV is made from millions of cells which are situated in between two panels of glass, with each cell holding a small amount of gas such as mercury vapor. This is then ionized by a voltage across the cell to produce ultra violet light. This UV light then hits the phosphorus pixels and razes the energy levels just like the CRT, producing different colors, by varying this voltage to the mercury cells will produce different colors’ on the screen.
However to ionize the gas in this way requires a large current and voltage, and as the UV light is absorbed by the phosphorus it also heats it up, this is why plasma TVs get hot over long periods of time. There are long strips of these electrodes feeding the voltage to the devices cells, as there is a control module which receives the signal required and alternates these voltages accordingly.
The picture below illustrates this operation:
Each pixel is made from three spate sub pixels each with different covered phosphorous, as these all blend together to form the color required, this serves the same operation as a shadow mask in CRT TVs as this can create billions of colours giving plasma TVs a high contrast ratio.Plasma TVs also use what’s known as pulse width modulation (PWM) to modulate the brightness by varying the current to each of the mercury vapor cells
Inside of monochrome plasma panels the gas is neon, which produces the orange glow, however they function a little differently from today’s plasma TVs as they do not emit UV light, as there is no other cells in front of the tubes of gas, instead it’s just the tubes of gas when ionized which make up the picture.
One main issue with early types of plasma screens (like the CRT monitor) was the burn in issue, where the screen would burn the plasma to the point it would either create a shadow of the image or black when the plasma could no longer illuminate. This made playing games almost impossible as they would damage the screen after a few hours due to static objects upon them.
The picture below shows this burn into an airport TV:
Another problem these plasma TVs exhibit (which can be confused with screen burn in) is when the screen is producing a white or black image, this will eventually cause the pixels used to be either on or off, and will create again a black shadow when the pixels are off or extremely white when the pictures are on rending viewing impossible.
Plasma screens are usually much brighter than most other types of TV, meaning they draw more power than the rest too. They can heat up to 120 degrees if remained on for long periods of time, this heat and power has a liner correlation to what’s being shown on the TV as a pure white screen left on would make the screen hot and use a lot of power. They have an average life expectancy of around 27 years if used for 10 hours a day, while also using a lot of power.
On an average plasma TVs use up to 400-600 watts depending upon their size, but they can also be much thinner and lighter than most TVs. Their thickness can be reduced to only a few cm in today’s market while keeping a huge size. The size of these TVs is its redeeming factor as plasma TVs can go up to and beyond the 90inch mark, making them some of the largest public TVs which can be purchased.
A advantage to this type of TV is it can create better contrast ratios between colours and can out do most other TVs with its ability to produce deep strong colours, however on a sunny day or in a well lit room these TVS suffer glare and loss of colour saturation due to the other lights directly effecting its performance.