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LED display effect can improve really

With almost all manufacturers started to promote and support led strip lights , LED instead of traditional tube type backlighting (CCFL) has become the inevitable trend. But with LED from the beginning of this year began to officially enters the large-scale mass production stage, so using LED back light on the market of product display relatively the proportion of the still is not very big, the traditional CCFL back light display products still occupy the mainstream market position, considering the backlight factory is still the certain scale CCFL backlighting capacity, so CCFL back light also won't immediately be eliminated.

LED backlit display is also a kind of LCD

When each big manufacturers LED this concept launched, we see a lot of users and consumers for this concept still exist some misunderstanding, will be LED LCD completely confused and get that in the BBS put forward in "now I should buy LED display or LCD". In fact, we usually say here LED refers to the liquid crystal display is the back light, it is by the multiple LED light emitting diode particles of composition, belong to LCD part of a used instead of the traditional CCFl back light (similar to our common fluorescent tubes), therefore LED and LCD belong to affiliate relationship, not parallel relationship.

Really have LED backlighting than CCFL better?

It is because of LED backlighting became strong enough, and manufacturers of the publicity, let a lot of LED back light don't know much about consumers feel very confused, didn't know whether they actually need to spend 200 to 300 yuan to choose and buy a LED back light products, or have been questioned: best led light bulbs as each big display will really as good as manufacturers of publicity, its colour effect as well as to monitor all aspects of the performance will improve? If really had increased, mainly in what place do better?

LED backlighting will improve LCD benchmark performance?

Below we will through the specialized equipment to the CCFL back light respectively, and LED the back light of liquid crystal display detailed test. In order to let the test results is more contrast value, we select the low-end respectively from the market and high-end products LED backlighting, come and the back light a CCFL high-end LCD products are compared. We come down into the performance test of the parts, use of the instrument is Topcon BM-7 A brightness chromaticity instrument.

Benchmark test items and instructions

Topcon BM-7 A brightness chromaticity apparatus is liquid crystal display to do the benchmark instrument. In testing before, we will take the test every one of the LCD monitor back to the factory model, and close the dynamic contrast functions and all color enhancement technology. At the same time, in the testing before we let art zhuo FX2431 LCD monitor normal work continuously a hour. In order to ensure the accuracy of the data, we test environment for not pervious to light the darkroom, and manual shut down each of the display of the indicator. Moreover, given the different video card to each type of display may affect the results of the final product, so we all use exactly the same host to as a test platform. And the color test different is, benchmark test reflects the LCD monitor the most basic performance and quality, and we learn language similar to the "basic common sense", then for everyone a way introduced four big test project:

1, brightness not uniformity

Because of various points display screen is not the same brightness actual, according to monitor product is different, every section type screen brightness difference between each area also will be different, we usually use "brightness not uniformity" this value to quantify the difference and the calculation method is monitor center around the average of the brightness divided by brightness, namely "the center/corner", this ratio more close to 1, the screen brightness difference that each part of the smaller, shows the better the results. Test the brightness of the liquid crystal display uniformity numerical still and average brightness, on the screen take 17 points, respectively in all white test the picture brightness, finally calculated the center/corner of values.

2, black screen not uniformity

And brightness not uniformity of similar is, black screen not uniformity is in full display said black picture each area brightness difference, and it can also be very accurate show LCD monitor control the ability of the row, the ratio, the bigger the row that control the uneven. Test black screen not uniformity of the method and the same round of test, but will all white picture perfect replacement black screen, same its numerical is closer to 1, the better.

3, chroma not uniformity

In addition to the outside brightness difference, and the screen each area will also have the shade of the difference. And the brightness on uniformity test the same is in testing chromaticity inhomogeneity will still take out when the screen 17 points, use BM-7 A are tested each point chromaticity coordinates (x and y values), and finally calculated the center chroma value/corner chromaticity of the values of the results, this ratio data smaller may be more beautiful.

4, NTSC color threshold

I believe we have the numerical has very understand, here we will no longer do too much in the paper. The test method is the use of BM-7 A test respectively, red, green, and blue chromaticity coordinates of brightness and value, and chromaticity coordinates according to calculate three primary colors point as determined the triangle area, its and NTSC 100% of the ratio of the triangle area is the NTSC color threshold. Color gamut that the higher the value of this display to show more rich color. The next three group is the test displays graphical results.

In my of publicity, part of the display manufacturers will ever LED back lighting source distribution more uniform as a selling point and the special features of publicity. But through our practical contrast, can see the CCFL LCD backlighting high-end and high-end LED backlighting of liquid crystal in distributing basically can achieve tied, both sides of the brightness distribution uniformity of basic quite, but the economy model in this aspect LED backlighting basic no advantage, the distribution of the apparent brightness as the other two of end products.

Next we come to see more benchmark performance comparison test results.

But in the corresponding black screen uniformity, the liquid crystal in high-end LED backlighting the link in the test showed a good effect, the picture is all black picture when the brightness of the distribution to more uniform. And the economy LED backlighting and high-end CCFL LCD backlighting LCD uniformity in a basic level. Below we to the contrast of color uniformity.

And in color uniformity, from the diagram above can see high-end LED backlighting chromaticity uniformity of liquid crystal in has very good expression, the whole color part is almost a plane, and the other two have more or less convex, especially the economy LED backlighting uniformity, the chroma of the performance than the high-end CCFL back light products.

NTSC color contrast threshold

Next we is to use BM-7 A brightness chromaticity instrument to test this in A few different types of LCD NTSC color threshold.

The ordinary CCFL back light of liquid crystal displays and CRT display of color gamut value in about 72% of all, and from the above form, can see the white LED back light LCD color gamut value and in this numerical nearby, so it won't to display color gamut value play the role of any improvement. And with a special CCFL back light (such as join phosphorus powder material) later, its color gamut value will be increased to 92% or higher, and so far we don't have a method in white LED back light through the method of adding special material to improve color threshold, only in three color LED back light display products (such as samsung, to XL20 VLED221wm), have wide gamut properties.

Benchmark performance comparison test analysis

From the above the benchmark results, can see and not all using LED back light products can obtain very good test results. In a number of tests, CCFL LCD backlighting high-end LED backlighting and liquid crystal basically can tied, even if lost, also won't have too big gap. And the low end of liquid crystal displays LED backlighting is relative to both before at a distance. That LED backlighting and is not everything, in the benchmark test, also is not as simple as using LED backlighting products, the effect will be well.

The guide LED back light reflex the light uniformity to play a very important role

And any products are all the same, the LED back light quality also is divided into high quality, ordinary and low-end several level. Those who USES the high quality LED back light monitor product, while in the price to be much higher, but the quality and performance of natural also can be guaranteed. And it also shows that the test, low LED back light although cheaper, but the actual performance and effect may not even traditional CCFL back light.

The cost of the factors, the present market condition most liquid crystal displays using LED back light all belong to the white light side buy type LED, in the dismantling of the article before, we will also be able to see the true colors looming (such as above). The so-called side LED is all buy type LED all in the up and down the particles on both sides, so that the display brightness, chroma totally depends on the uniformity of the panels and light the stand or fall of membrane filtration. After excellent craft treated guided panels can be a LED light even covering the entire display screen, such as in the chromaticity uniformity tests, high-end LED LCD is made very perfect result; Cheap and setting is still can let the uneven distribution of light, than CCFL back light monitor product worse performance, so the quality of the sun also decides display brightness and color uniformity final stand or fall.

LED backlighting on the colors will improve?

In the above the benchmark test, we can see a white LED is not the color gamut displays has any effect, its NTSC color gamut value still keep at about 72%, nothing has changed. So in the characteristics of color, with the average white LED CCFL back light will have what different?

Most LED back light (white closed curve to the yellow special rendering

It is our brand, the same series based on the same two of liquid crystal displays (just back light type different) of the ICC documents color characteristic analysis of the results. One of the white closed curve model for LED backlighting, and red for CCFL LCD backlighting. From the diagram above, we can see the yellow liquid crystal main LED backlighting to part of the color is more special rendering, namely in the display yellow part, its than CCFL LCD backlighting more bright-coloured and exaggerated. This is not only the a brand appear such phenomenon, we test LED backlighting display of all have this feature. But because the color gamut value is the same, so in yellow start exaggerating the rendering while, also let the green and blue can appear some saturation relative enough.

Color reduction at the top of the list of the accuracy by using wide Angle of the panel display primarily

And in color accuracy reduction from above, we see row in front of the more widely used in perspective of the panel display products, and wide Angle panel and LED back light description of the same part is not, so can see decided to display color reduction of accuracy is more factors the type of the LCD panel, and displays of IC chips of ability, to the display is using LED back light correlation is not great.

From the above tests, we can see LED back light is not the accuracy of liquid crystal display color reduction have little impact on the part of the LCD panel type and to this part of IC chips much more influence. And in color characteristics, most LED back light will make the display to highlight the yellow part, but the green and blue relative lack of CCFL slightly, but we can't say who must be more strong, can only say that both the present a different style.

Conclusion: the choose and buy don't listen to JS blind persuasion

Because for most consumers LED is still a new thing, and the is not very understand, so many dealers sales staff will to each consumer "vigorously" promotion LED back light products. The so-called "vigorously", it is to point to some good dealer with many people on the characteristics of half a solution has been LED to some of the characteristics of the propaganda greatly exaggerated, to lure more customers to buy the LED backlighting display products.

Not all of the display has LED backlighting "magical effect"

In the BBS and page message, we often can see many net friend in whether twisted should buy the products LED backlighting. After all, this is the mainstream market and the trend, and also some dealers with "persuasion," said LED back light how to how good a great improvement on the color such as exaggerated propaganda. And through this paper professional test, we can see for the high quality LED the back light liquid crystal display is concerned, its benchmark performance can be achieved really pretty good effect, and in individual test will be slightly better, but drew back "a large gap". And to some prices look very attractive three lines, even as inferior brand display, consider the cost factors they may not be using the excellent quality of the products LED backlighting, and after our test, can see these cheap products both in LED backlighting benchmark testing, or in colour characteristics are not any relative CCFL backlighting advantage, and may have even than CCFL backlighting effect more poor.

And in color characteristics and the accuracy of the color reduction, this paper we have detailed introduction on the accuracy of the panel type and more with the IC chip, this effect LED backlighting is not much; And in characteristics, most LED back light will be part of yellow exaggerated performance, but because of its overall color gamut not any better, so the yellow exaggerated after the performance, on the green and blue saturation also declined, show different color style, but can't say who actually can better than who.

Finally in energy saving, we in the previous articles have used in many test had LED back light in low power consumption of obvious advantages, like samsung, LG, LG such LED backlighting product, its 23 or 24 inches of LED LCD, power consumption value can control in about 20 W, than CCFL backlit widescreen 19 of the lower power consumption, so in energy saving, has LED backlighting victory.

So everybody in the choice of liquid crystal displays when don't listen to the dealer disorderly persuasion, also have LED Tube grades, only is excellent products LED backlighting, will make some advantage, and not all LED backlighting is "good goods", the excellent CCFL backlighting product is worth the same choose and buy. But if you pursue more energy efficient, LED backlighting is still the best choice.