How to judge the quality of TV LCD screen
Author:Kaka Time:2021-10-13 14:40 Browse(590)
1、 Don't be greedy for the cheap
1、 At present, the price of 32 inch LCD TV is below 9000 yuan, but experts point out that the price of 32 inch LCD TV with stable quality is still around 1000 US dollars, and 8999 yuan is absolutely not enough to buy a good LCD TV The mainstream size of this year's LCD TV is 32 inches.
if you want to install LCD TV in your bedroom,
it is most suitable to buy 32 inch or even 23 inch LCD TV. The price of 5000 yuan is more suitable for the consumption level of Chinese consumers.

How to judge the quality of TV LCD screen


3 Pay attention to the technical parameters
the most important technical parameter of LCD TV is the reaction speed.
at present, the best reaction speed is about 8 ms, but the price is high, so it's enough to buy 12 to 15 ms; Secondly, we should pay attention to the resolution, preferably at 1280 × 768 or above; Thirdly, the angle of view of TV is also very important, and the angle of view of the latest LCD TV can reach more than 176 degrees; In addition, color saturation is also an important technical parameter.

4. Find out the screen providers.
although there are not many manufacturers producing LCD screens.
the screens of different manufacturers are quite different, so you should first know the manufacturers of LCD screens when purchasing, and the products of sharp, Samsung Sony and LG Philips are the best.


1 Look at after-sales service guarantee

although LCD screen is not easy to have problems.
but if there is a problem, maintenance is a very troublesome thing.
most manufacturers provide warranty services ranging from 1 to 3 years.
some manufacturers even provide free on-site service and maintenance fee reduction within the warranty period. It's better to ask for these details before purchasing.


2. Judging bad points

the most common problem of LCD screen is "bad points"
although many products claim that their products have "no bad points", different manufacturers have different evaluation standards for bad points. Some manufacturers provide new services as long as they have bad points, and some must judge according to the evaluation standards of camera. How long does it take for a product to have bad points to be considered as a product defect? Or more than a few points are considered bad points? These evaluation criteria should be clear, so as not to damage the rights and interests.
generally, high-quality LCD TVs have strict control over the number of bad points.


3. Screen selection should not be too large.

traditional TV displays are advertised as 17 inches in specifications.
however, there is one inch left and right around the panel, which can not be used for display, The actual visual size is only about 15 inches.
and the LCD screen indicates 15 inches.
the actual visual size is 15 inches.
when buying a machine, consumers should choose the appropriate size according to the size of the room.
to avoid the pressure caused by too large screen.
if the living room area is about 30 square meters.
choose a 32 inch LCD TV.

4 Viewing angle

only for the LCD on the market.
the viewing angle is left-right symmetrical (that is, the angle at which the image on the screen can be seen from the left or right is the same.
for example, the viewing angle on the left is 60 degrees.
the viewing angle on the right must also be 60 degrees).
and the viewing angle on the up and down is usually less than that on the left and right.
from the user's point of view Of course, the larger the viewing angle is, the better.


5. Brightness selection

brightness refers to the brightness of the screen.
2The unit is CD / m2 or nits.
at present, there are two ways to improve the brightness: one is to improve the light transmittance of LCD panel; The other is to increase the brightness of the backlight source.


low brightness is not conducive to the clear display of the video picture.
for some dim scenes, it is even more helpless.
in addition,
the brightness uniformity of the screen is also very important, However, there is no indication in the product specification of LCD TV.
whether the brightness is uniform or not.
and the number of backlight and reflector are closely related to the configuration mode. For better quality TV, the brightness of the picture is uniform, and there is no obvious bright area.
this point.
when the picture is switched to the black screen state, it is easier to capture the uneven brightness.


6 Color selection

the color gamut of LCD is not as wide as that of CRT.
therefore, LCD TV is not as wide as CRT TV from the perspective of real object color.
when purchasing LCD TV.
choosing models with more color adjustment functions is conducive to adjusting images closer to natural colors.


7 Pay attention to the contrast

the screen contrast of the general entry-level models is mostly 300:1.
the medium-level models have 450:1 and 500:1 levels. If you compare the image display ability of the entry-level and high-level models, and have a high contrast screen, the effect of color gradients will be more obvious, and the color performance will be more lively and rich, which mainly depends on the needs of users.


8 The response time should not be more than 16ms

due to the limitation of imaging principle.
the display response time of LCD TV is too long, which is reflected in the image that is prone to residual shadow and trailing of moving image,This is very unfavorable for the film and television programs based on dynamic images.
of course, the smaller the index is, the better.
through the efforts of major LCD manufacturers.
at present, most of the LCD screens used in TV have achieved a response speed of about 16ms, which basically does not constitute a problem for the appreciation of TV programs.


9 Image resolution

the resolution of LCD TV is fixed.
please remember this! Not like a computer LCD, The resolution can be adjusted.
the fixed resolution of LCD TV is also its best resolution.
high resolution can be easily compatible with HDTV.
for any video signal that is not the best resolution of LCD screen.
LCD TV needs to convert the image resolution before display conversion.


for LCD TV,
resolution is one of the important parameters.
the resolution of LCD TV can be adjusted The resolution supported by traditional CRT TV is more flexible.
however, the pixel spacing of LCD TV has been fixed, so it does not support as many display modes as CRT TV.
the best resolution of LCD TV.
also known as the maximum resolution, LCD TV can show the best image.


when LCD TV presents the display mode with low resolution.
there are two ways to display.
the first one is the center display: for example, in XGA 1024 × The SVGA 800 is displayed on the screen of the 768 × 600.
only 800 in the middle of the screen × At present, this method is rarely used.
another method is called extended display: when displaying a picture with a resolution lower than the best resolution.
this method is used to display a picture with a resolution lower than the best resolutionAt present, there are mainly 800 LCD TVs × 600、1280 × 768 and 1366 × 768 and other common resolutions.


10, screen refresh rate

for LCD display,
high or low refresh rate will not make the picture flicker.
when the refresh rate is 60Hz.
LCD can get a good picture.
in LCD display,
each pixel will continue to light up until the non luminous signal is sent to the controller, Therefore, LCD display will not flicker due to continuous charging and discharging.


11 The service life is no less than 50000 hours.

some low-cost LCD TVs also have short service life.
therefore, special attention should be paid to the service life of backlight.
generally, the service life of backlight of LCD TVs is more than 50000 hours.
that is to say.
if you use LCD TVs for an average of 5 hours a day, The life of that 50000 hours is equal to 27 years that you can use the LCD TV.
the working principle of LCD is that the backlight irradiates the liquid crystal molecules and transmits light.
generally, the number of gray-scale digits that can be displayed on each color channel is used to describe the number of color digits on the panel.
if each color channel can display 256 (2 to the 8th power), it is called 8bit panel, That is true color panel; Similarly, if it can only display 64 (2 to the sixth power) gray scale, it is called a 6-bit panel, that is, a pseudo true color panel.
most of the LCD panels that can display 16.2M (actually only 0.26M) colors in the market need to enhance the color effect of the panel through software technology (that is, the "famous" software interpolation).
in this paper, the color effect of the LCD panel is analyzedThat is, 6bit panel; The LCD with 16.7M color is the real 8bit panel.

LCD response time

let's talk about the response time.
generally, the so-called response time refers to the total time required for a pure black or white pixel to disappear from display.
this time includes two periods of "up" and "down"; Because most of the display images are not pure black or white, but color. It is composed of different shades of sub-pixel of RGB primary color, and the variation of the shade of each sub-pixel, The so-called "gray scale" (gtog).
the concept of gray-scale response time has been ignored for a long time, and then it is proposed again.
in the past, the gray-scale response time of many displays with nominal 16ms response time actually exceeds 16ms.
for response time test, you can quickly move the mouse pointer under the black background.
or drag the file window to observe the shadowing phenomenon.
in order to reflect the reality The gray-scale response ability of LCD.
it can quickly convert different background colors and move color blocks to comprehensively check the response time of different color conversion.
if possible, it can play European and American movies of racing car class.
it can test whether the video playback is clear and whether there is drag shadow.


the best way to detect LCD highlights is to use professional test software.
it is necessary to use professional test software For example, monitors matter check screen can't be detected by testing software when purchasing LCD. At the same time, the merchants will display various gorgeous pictures to the consumers, and they can't see the bright spots at all. So, in the process of purchasing LCD,What is a good way to detect the bright spot of LCD? Methods to detect whether LCD has bright spots: one is to adjust the desktop background to all white or all black or other solid color observation, the other is to detect through WordPad.


1. Adjust the desktop background: take Windows XP system as an example.
right click "properties" on the desktop, first select the "desktop" tab, select "None", then select the "appearance" tab, and click "advanced", Select "desktop" from the drop-down menu of "project" in the interface, and then click various colors such as white, black, blue and red in the drop-down selection of "color", and then click "application" to produce the effect, Then use the "win d" shortcut key to switch to the desktop and carefully observe whether there are bright spots.


2. WordPad detection: open "run" in the "start" menu.
Enter "WordPad" in it to open the WordPad, and then slowly drag the WordPad on the desktop with the mouse. Try to drag every piece as far as possible, and carefully observe the dragged place, The principle of this method is to use the white background of the WordPad to check the LCD display.
at the same time, you can also check whether the LCD has color bias, especially in the four corners.
however.
this method must have a premise, that is, the LCD must be adjusted to a higher resolution, such as 1024 for a 15 inch LCD × 768.


the refresh rate of LCD

because of the working principle of LCD (described above).
no matter what the refresh rate is, there will be no flicker. For LCD, the refresh rate of 60Hz can meet the needs,Of course, if your LCD supports adjusting to a higher 75Hz, it will not have much impact on the display effect; Because the working principle of LCD depends on the service life of backlight, it is not necessary to set the screen saver when using LCD. It is recommended to turn off the display directly after n minutes of idle.
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