Television sets better known as t.v as used by mass media to broadcast programs for entertainment, enlightenment & information by means of transmitted visual images and sound.
Through the years there has been a technological advancement from past television to the screens we have today.It is therefore deemed necessary to outline and explain the types of televisions.
TYPES OF TELEVISION
- Cathode ray tube Television – this are the antique almost obsolete types of televisions. It consists of the oldest form of television like the black and white television to the later colored ones.An antenna, satellite dish brings the signal from a broadcasting station to the television set, the motherboard steps up the voltage by a flyback to power the cathode ray tube. it also selects the signal to be processed to the circuit base at the back of the projector gun. The projector gun then fires negatively charged electrons from projector gun which shoots red, blue, green signals to the screen upfront which holds positively charged anode.A deflection yoke is used to guide the beams on to every corner or desired area of screen. The screen is coated in phosphor which recreates transmitted the signal picture when shot with electrons through a shadow mask with holes for each color.
above is a black and white ancient cathode ray tube television and the next picture is a cathode ray tube color screen.
- Projection Television – they are either rear or front projection televisions. rear are lit from the back by projectors while front are lit from the front by projectors. Both are best viewed from in dark rooms. A front projector t.v uses a separate projector and a screen. in rear the projector is located at the back inside the t.v set. above is an example of a rear projection television set
- Liquid crystal display televisions – they were the first type of television to be made in smaller profile i.e thinner displays with better picture quality. They are also known as LCD and in modern technological advancement after an addition of a transistor a thin film transistor liquid crystal display i.e TFT. LCD monitor consists of six layers i.e a back light, a sheet of polarized glass i.e polarizer, TFT glass, a layer of liquid crystal solution, color filter or glass and a second polarized sheet of glass. There’s a Cold Cathode Fluorescent Lamp light source better known as the back light. This light is shined from the back of the panels and it passes through the 1st of 2 polarizer filters i.e the 1st polarizer only allows light passing through horizontal plane to pass through while the second only allows light passing through vertical plane to pass through it.Then the polarized light later passes
through a layer that contains many liquid crystals arrayed in tiny cells. at the very front there are many pixels which are just like in the cathode ray tube red, blue or green on each pixel. when electricity is passed the liquid crystals tend to untwist and align themselves either vertically or horizontally. by adjusting amount of electricity we can vary the light to the screen hence determining the color seen hence signal processed.
- DLP Television – Digital light processing television. A DMD i.e a Digital Micro-mirror Device is a chip made up of tiny tilt-able mirrors which forms the core of the DLP television. The video image is put on display on the DMD chip while the micro mirrors on the chip tilt very rapidly as the image changes. It should be noted that each pixel is one micro mirror, therefore it processes the gray scale image. there after color is added as light passes a high speed color wheel and is reflected off the micro mirrors on the DLD chip which rapidly tilt towards or away from the light source.light is amplified and bounced off the micro mirrors and sent through the lens reflected off the large single mirror right onto the screen.
- Plasma Television – Plasma screens are made of 2 sheets of glass with a mixtures of gases i.e neon and zenon stored between the layers which when charged to form plasma. its made of tiny cells and electrodes criss-crossing one another although charged neon and xenon only produce ultra-violet light invisible to human eye but in order to get the signal seen each cell has a phosphor red, blue and green in it. so if u vary the amount of current u can vary the colors hence create desired view.
- 3D capable televisions – in 3d TV view the moving images are produced separate,one image is sent to the viewer’s left eye and the other to the right. This gives proper illusion of three dimension, the left eye’s image must not be seen by the right eye, while the right eye’s image must not be seen by the left i.e stereopsis. This is why 3d glasses are used well besides the problem of having a distorted view without glasses. U can also use anaglyph glasses which are basically colored glasses with red on one side and cyan on the other. This allows for one eye to process the red colors and the other blue and green colors as projected on the RGB pixels. Basically a TV that can transmit two different images falls in this category.
- L.E.D Televisions – light emitting diode televisions. This are actually liquid crystal displays that are lit by Light emitting diodes instead of Cold Cathode Fluorescent Lamps as shown above. There are two types of l.e.d televisions; i.e Direct l.e.d – in this the l.e.d’s are set directly behind the screen while in Edge-lit l.e.d’s – in this the l.e.d’s are set around the television frame enhancing the screen to even be thinner.
- O.L.E.D Televisions – This stands for organic light emitting diode televisions. it uses organic materials i.e carbon to create light when supplied with an electric current. it is super thin because it is not back-lit. This have the capability of being curved and is self-emitting.
- Q.L.E.D Televisions – means Quantum dot light emitting diodes television technology which has semi-conductor nano-scale crystals which are used for back lighting only used in Samsung televisions.
COMMONLY USED TELEVISION & ACCESSORY TERMINOLOGY
- Contrast Ratio – This is the difference between the brightest whites and the darkest black colors the screen can display.
- Composite – yellow video cable that connects former analog signal into the TV.
- Refresh Rate– it details how often the display will refresh the image made on the screen.
- Component: this refers to cable connection splitting video into three signals. it is also known as RCA cable, phono connector or Cinch connector.
- HDMI – High definition multimedia interface. used to view perfect picture quality.
- HDTV – High definition television.
- DVI -Digital visual interface. i.e used to process digital signal.
N.B – Most of this TV’s above can be used as computer monitors or the same technology can be used to build a computer monitor or oscilloscope.