- published: 14 May 2016
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A backlight is a form of illumination used in liquid crystal displays (LCDs). As LCDs do not produce light by themselves (unlike for example Cathode ray tube (CRT) displays), they need illumination (ambient light or a special light source) to produce a visible image. Backlights illuminate the LCD from the side or back of the display panel, unlike frontlights, which are placed in front of the LCD. Backlights are used in small displays to increase readability in low light conditions such as in wristwatches, and are used in computer displays and LCD televisions to produce light in a manner similar to a CRT display. A review of some early backlighting schemes for LCDs is given in a report by Peter J. Wild IEEE First-Hand History under its section Backlit LCDs.
Simple types of LCD displays such as in digital watches are built without an internal light source, requiring external light sources to convey the display image to the user. Most LCD screens, however, are built with an internal light source. Such LCD screens consist of several layers. The backlight is usually the first layer from the back. But in order to create screen images, a mechanism is needed to regulate the light intensity of the screen's pixels. For this, light valves are used that vary the amount of light reaching the target by blocking its passage in some way. The most common element is a polarizing filter to polarize the light from the source in one of two transverse directions and then passing it through a switching polarizing filter, to block the path of undesirable light.
Liquid-crystal-display televisions (LCD TV) are television sets that use LCD display technology to produce images. LCD televisions are thinner and lighter than cathode ray tube (CRTs) of similar display size, and are available in much larger sizes. When manufacturing costs fell, this combination of features made LCDs practical for television receivers.
In 2007, LCD televisions surpassed sales of CRT-based televisions worldwide for the first time, and their sales figures relative to other technologies are accelerating. LCD TVs are quickly displacing the only major competitors in the large-screen market, the plasma display panel and rear-projection television. LCDs are, by far, the most widely produced and sold television display type.
LCDs also have a variety of disadvantages. Other technologies address these weaknesses, including organic light-emitting diodes (OLED), FED and SED, but as of 2014 none of these have entered widespread production for TV displays.
A light-emitting diode (LED) is a two-lead semiconductor light source. It is a p–n junction diode, which emits light when activated. When a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light (corresponding to the energy of the photon) is determined by the energy band gap of the semiconductor.
An LED is often small in area (less than 1 mm2) and integrated optical components may be used to shape its radiation pattern.
Appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared light. Infrared LEDs are still frequently used as transmitting elements in remote-control circuits, such as those in remote controls for a wide variety of consumer electronics. The first visible-light LEDs were also of low intensity, and limited to red. Modern LEDs are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness.
An LED-backlit LCD is a flat panel display which uses LED backlighting instead of the cold cathode fluorescent (CCFL) backlighting used by most other LCDs. LED-backlit LCD TVs use the same TFT LCD (thin film transistor liquid crystal display) technologies as CCFL-backlit LCD TVs. Picture quality is primarily based on TFT LCD technology, independent of backlight type. While not an LED display, a television using this display is called an “LED TV” by some manufacturers and suppliers. In the UK, the Advertising Standards Authority has made it clear in correspondence that it does not object to the use of the term “LED TV”, but requires it to be explained in advertising.
Three types of LED may be used:
How do different types of display backlights work, and how do they affect image quality? Audible message: Thanks to Audible for supporting our channel. Get a free 30 day trial at http://www.audible.com/techquickie. Thanks to Tyler Pruitt from SpectraCal for assisting us with this episode, and for the spectral measurement graphs. Follow: http://twitter.com/linustech Join the community: http://linustechtips.com License for image used in this video: https://creativecommons.org/licenses/by/2.0/legalcode
How to fix LED LCD TV, Vizio and LG backlight TV repair, this is full backlight repair guide, full disassemble, testing, ordering parts, fix, assemble of the Vizio or LG LED TVs, factory reset won't fix tv, LED backlight repair kit here-http://bit.ly/2a2njb6 and Back-light tester http://bit.ly/2alOhXu The repair guide also works on Samsung TVs, Sony, LG, Vizio LED TVs that have dark image black or no picture but audio sound. "TV has sound but no picture" Part 1 how to troubleshoot LED LCD TV no picture black screen dark image but OK audio sound volume http://bit.ly/29TDbL1 backcover is screwed & clipped on, use flathead driver, wedge in cover edges & twist to pop off cover. Tester was given to me for a howto video. thanks shopjimmy.com
Want to help the subjects of your videos stand out? Try backlighting. Learn about different types of backlighting in this tutorial. Watch the follow-up movies at http://www.lynda.com/Video-Shooting-Video-tutorials/Pro-Video-Tips/129017-2.html?utm_campaign=Flg_x935MCY&utm;_medium=social&utm;_source=youtube-earned. This specific tutorial is from the Pro Video Tips series presented by lynda.com author Anthony Q. Artis. Pro Video Tips offers a new video tip every week, on topics like shooting techniques, storytelling, audio, and miking.
http://www.adorama.com Just because there’s harsh midday light doesn’t mean you need to put your camera down or get out an arsenal of strobes and reflectors to try to save the day. In fact, by simply learning how to work with backlight, you will have a tool that will allow you to continue working from sunup to sundown. In this Tech Tip, photographer and director Corey Rich works with a trail runner in the Sierra Nevada Mountains to show why backlighting works midday. He creates compelling, beautiful images by exposing for the shadows, using a shallow depth of field, and creating a natural rim light that separates his subject from the background. Learn to make any light work to your advantage by shooting backlight. Related Products at Adorama: Nikon D4s DSLR Camera Body http://www.ador...
👉 Check out our new LIVE channel where we livestream board repair https://www.youtube.com/channel/UC6nZlvfz4YWoBWbjiaYJA3g ▶ On newer Retina Macbook Pros, there are new elements to the backlight circuit that must be part of our MAIN diagnostic checklist. Please add these routines to yours! ✖ TOOLS SUGGESTED: ● Soldering Iron: http://amzn.to/2cKkMyO ● Preferred tip: http://amzn.to/2d5MgPn ● Micro Soldering Pencil: http://amzn.to/2d5MWUP ● Micro soldering tip: http://amzn.to/2qUSFDh ● Hot Air station: http://amzn.to/2d5M7Lw ● Microscope & LED light: http://amzn.to/2iLrE16 http://amzn.to/2nzfPT2 ● CHEAP Microscope: http://amzn.to/2rTlHbj ● Flux: http://bit.ly/2cYIx7t ● Solder paste: http://bit.ly/2epK1JE ● Tweezers: http://amzn.to/2d5NBpi ● On-Screen multimeter: http://amzn.to/2qG0Bse Setu...
EASY LED LCD TV FIX - LED backlight strip repair kit fixes TVs no brightness no picture black screen no video image, NOTE if 1 LED is burnt out then the TV backlight circuit won't turn on, How to fix LED LCD TV no backlight- https://www.youtube.com/watch?v=YgaL6X6eSaU LED backlight strip work station- http://bit.ly/2dlsWOB TV backlight tester- http://bit.ly/2alOhXu 12 LEDs & Diffuse Lens for LG LED strips- http://bit.ly/2d9SHnd LG / Vizio LED Strips- http://bit.ly/2a2njb6 this is "easy tv repair" i believe anyone can do, this show "how to use a meter" and replace LEDs on the backlight strip.
How to Test LED Backlighting CLICK HERE to Purchase: http://www.shopjimmy.com/sid-gj2c-led-tv-backlight-tester.htm?utm_source=youtube&utm;_medium=sid-gj2c-led&utm;_campaign=sid-gj2c-led Here we have the SID GJ2C LED TV backlight tester. This tester uses AC power and comes with two test probes. There are multiple tests that can be run using this device. You can test the cable running to the LEDs in your TV. You can test and individual LED strip. And also you can test individual LEDs. One great thing for TV repair, is if you have the symptom of no backlights in your LED TV, you can use this device to help determine if the problem is the LED backlights or the power supply/LED driver board, by directly testing the backlights. The first test we will show, is how to test the cable runni...
Instructional video explaining easy way to test individual LEDs on a strip from a TV backlight.
Watch more How to Take Portraits videos: http://www.howcast.com/videos/514388-How-to-Backlight-a-Photo-Portrait-Photography Hi, I'm Joe. I teach photography at the school of visual arts in New York. Today, we're going to talk about how to deal with a back lit subject. The problem with a back lit subject is that all of your light is coming from behind which makes this side of your subject a shadow and what you normally get for that is a silhouette. That's where your camera's going to kind of inclined to give you and the first and easiest way to deal with that is to just take your camera's exposure reading and open up one or two stops from what it says to do, so that the camera's going to indicate that you're over exposed by one or stops, but that over exposure is what's going to open up ...
Sometimes TVs are just not economical to repair.
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