HOW TV MADE

8/3/2019 HOW TV MADE

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first plasma prototype appeared back in 1964.

use a matrix of tiny gas plasma bubbles coatedby phosphor and charged by precise electricalvoltages to create a picture.

Can display 68 billion (236 ) vs LCDs 16.7million (224) colors


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twisted nematic (TN) is the most common type liquidcrystal used in display applications

crystal reacts to electric currents in predictable ways,such as untwisting to varying degrees depending onthe voltage of the current to which it is exposed

main difference between plasma and LCD technologyis that LCD pixels dont emit light

LCD displays need white backlighting.

The light emitted by the backlighting passes throughthe liquid crystal and is then colored by a filter.

Each subpixel has the same characteristics; only thecolor of the filter changes depending on the pixel.


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The liquid crystal of each subpixel can be controlledelectrically like a valve; the amount of light allowed to passthrough the crystal governs how much red, green and blueis emitted for each pixel.

Active matrix LCDs employ thin film transistors (TFTs),m ortiny switching transistors and capacitors arranged in amatrix on a glass substrate, to direct electric charges downcolumns to reach a particular pixel.

In turn, this causes the liquid crystals to untwist and displaya predetermined amount of light generated by the lightsource usually a fluorescent bulb located in back of them.By exploiting a combination of red, green, and bluesubpixels of various intensities (or gray scales), a singlepixel triad can reproduce approximately 16.8 million colors.


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OLED is a solid-state semiconductor devicethat is 100 to 500 nanometers thick or about 200times smaller than a human hair.

OLEDs can have either two layers or threelayers of organic material; in the latter design,the third layer helps transport electrons fromthe cathode to the emissive layer


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Substrate (clear plastic, glass, foil) - The substrate supportsthe OLED

Anode (transparent) - The anode removes electrons (addselectron "holes") when a current flows through the device

Organic layers - These layers are made of organic moleculesor polymers. Conductinglayer - This layer is made of organic plastic molecules

that transport "holes" from the anode. One conducting polymerused in OLEDs is polyaniline

Emissive layer - This layer is made of organic plastic molecules(different ones from the conducting layer) that transport electrons

from the cathode; this is where light is made. One polymer used inthe emissive layer is polyfluorene

Cathode (may or may not be transparent depending on thetype of OLED) - The cathode injects electrons when acurrent flows through the device


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The color of the light depends on the type oforganic molecule in the emissive layer.Manufacturers place several types of organic

films on the same OLED to make colordisplays.

The intensity or brightness of the light dependson the amount of electrical current applied: themore current, the brighter the light.


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PMOLEDs have strips of cathode, organic layersand strips of anode.

The anode strips are arranged perpendicular to the

cathode strips. The intersections of the cathode andanode make up the pixels where light is emitted.

External circuitry applies current to selected stripsof anode and cathode, determining which pixels

get turned on and which pixels remain off. Again,the brightness of each pixel is proportional to theamount of applied current.


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Active-matrixOLED (AMOLED)AMOLEDs have full layers of cathode, organicmolecules and anode, but the anode layer

overlays a thin film transistor (TFT) array thatforms a matrix.

The TFT array itself is the circuitry thatdetermines which pixels get turned on to forman image.


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TransparentOLEDTransparentOLEDs have only transparentcomponents (substrate, cathode and anode)

and, when turned off, are up to 85 percent astransparent as their substrate. When atransparentOLED display is turned on, itallows light to pass in both directions. A

transparentOLED display can be either active-or passive-matrix. This technology can be usedfor heads-up displays.


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Top-emittingOLEDs have a substrate that iseither opaque or reflective. They are best suitedto active-matrix design. Manufacturers may

use top-emittingOLED displays in smart cards


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Foldable OLEDs have substrates made of veryflexible metallic foils or plastics.

Foldable OLEDs are very lightweight and durable.

Their use in devices such as cell phones and PDAscan reduce breakage, a major cause for return orrepair.

Potentially, foldable OLED displays can be

attached to fabrics to create "smart" clothing, suchas outdoor survival clothing with an integratedcomputer chip, cell phone, GPS receiver and OLEDdisplay sewn into it.


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WhiteOLEDs emit white light that is brighter,more uniform and more energy efficient thanthat emitted by fluorescent lights.

WhiteOLEDs also have the true-color qualitiesof incandescent lighting.

BecauseOLEDs can be made in large sheets,they can replace fluorescent lights that arecurrently used in homes and buildings. Theiruse could potentially reduce energy costs forlighting.

HOW TV MADE

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