How does LCD work???
Author:Zheng HuNian Time:2021-07-20 16:50 Browse(888)
Physical properties of liquid crystal
1) The physical properties of liquid crystal are: when the power is on, the liquid crystal turns on.
the arrangement becomes orderly, which makes light easy to pass through; When the power is off, the arrangement is disordered to prevent light from passing through.
let the liquid crystal block or let light pass through like a gate.

How does LCD work???

technically speaking, the liquid crystal panel contains two pieces of rather delicate sodium free glass material, called substrates, with a layer of liquid crystal in the middle.
when the light beam passes through this layer of liquid crystal.
the liquid crystal itself will stand or twist irregularly, Most liquid crystals are organic compounds.
they are made up of long rod-shaped molecules.
in the natural state, the long axes of these rod-shaped molecules are roughly parallel.
the liquid crystals are poured into a well-made slotted plane.
the liquid crystal molecules will be arranged along the grooves, so if those grooves are very parallel, the liquid crystal molecules will be aligned, (2) the principle of monochromatic liquid crystal display.
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LCD technology is to pour liquid crystal between two planes with thin grooves.
the grooves on the two planes are perpendicular to each other (intersecting 90 degrees).
that is to say,
if the molecules on one plane are arranged in the north-south direction, the molecules on the other plane are arranged in the east-west direction, The molecules between the two planes are forced into a state of 90 degree torsion.
because the light propagates along the alignment direction of the molecules,
the light is also twisted by 90 degrees when passing through the liquid crystal.
however, when a voltage is applied to the liquid crystal,
the molecules will rearrange vertically, making the light direct out, However, there is no twist.
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LCD depends on the polarization filter (plate) and the light itself.
The natural light is scattered randomly in all directions.
the polarization filter is actually a series of thinner and thinner parallel lines.
these lines form a net.
block all the light that is not parallel to these lines.
the line of the polarization filter is just perpendicular to the first one.
so it can completely block the polarized light.
only the lines of two filters are completely parallel.
or light The LCD itself has been twisted to match the second polarization filter, so the light can pass through.
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LCD is composed of such two mutually perpendicular polarization filters.
so under normal circumstances, all the light that is trying to pass through should be blocked.
however.
because the two filters are filled with twisted liquid crystal, after the light passes through the first filter, the LCD will be able to pass through the first one, On the other hand,
If a voltage is applied to the liquid crystal, the molecules will be rearranged and completely parallel, so that the light is no longer twisted, so it is just blocked by the second filter.
in a word,
power will block the light line, and no power will make the light emitted.
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however,
the liquid crystal arrangement in the LCD can be changed, However, the computer screen is almost always on.
therefore, only the scheme of "power on to block the light" can achieve the most power saving.
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from the perspective of the structure of LCD.
whether it is a notebook computer or a desktop system, The LCD screen used is a layered structure composed of different parts.
the LCD is composed of two glass plates.
the thickness is about 1 mm, between which there are 5 glass plates containing liquid crystal (LC) material μ M evenly spacedBecause the liquid crystal material itself does not emit light.
there are light tubes as light sources on both sides of the display screen. On the back of the liquid crystal display screen, there is a backlight plate (or uniform plate) and a reflective film. The backlight plate is composed of fluorescent materials, which can emit light, Its main function is to provide a uniform background light source.
the light emitted by the backlight enters the liquid crystal layer containing thousands of crystal droplets after passing through the first layer of polarization filter layer.
the crystal droplets in the liquid crystal layer are contained in a small cell structure.
one or more cells constitute a pixel on the screen.
there is a transparent electric field between the glass plate and the liquid crystal material The electrodes are divided into rows and columns. At the intersection of rows and columns, the optical rotation state of liquid crystal is changed by changing the voltage. The liquid crystal material acts like a small light valve.
around the liquid crystal material are the control circuit and the driving circuit.
when the electrode in the LCD generates an electric field.
the liquid crystal molecules will be distorted, The light passing through it is refracted regularly, (3) the working principle of color LCD.
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for the more complex color displays that need to be used in laptop or desktop LCD.
there should also be a special color filter layer for color display.
usually.
in the color LCD panel, Each pixel is made up of three liquid crystal cells, and each cell has a red, green or blue filter in front of it.
in this way,
light from different cells can display different colors on the screen.
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LCD overcomes the disadvantages of CRT, such as huge volume, power consumption and flicker.
LCD can display different colors on the screenBut at the same time, it also brings some problems, such as high cost, not wide viewing angle and color display is not ideal.
CRT display can choose a series of resolutions.
and it can be adjusted according to the screen requirements, but the LCD screen only contains a fixed number of LCD cells, Only one resolution display can be used on the full screen (each cell is a pixel).
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CRT usually has three electron guns.
the electron flow emitted must be accurately concentrated, However, LCD has no focus problem.
because each LCD unit is switched on and off separately.
this is why the same image is so clear on LCD screen.
LCD does not need to care about refresh rate and flicker.
LCD unit is either on or off, Therefore, the image displayed at a low refresh rate of 40-60hz will not flicker more than the image displayed at 75Hz.
however,
the LCD unit of the LCD screen will be prone to defects.
for 1024 × 768.
each pixel is composed of three units, which are respectively responsible for the display of red, green and blue, so a total of about 2.4 million units (1024 × seven hundred and sixty-eight × 3=2359296).
it is difficult to ensure that all these units are intact.
most likely, some of them have been short circuited (a "bright spot"), Or open circuit (appear "black dot").
so.
not so expensive display products will not appear defects.
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LCD display contains some things that have not been used in CRT technology.
the fluorescent tube coiled behind the screen is the light source for the screen.
sometimes.
the light source for the screen is the fluorescent tubeSome bright lines may appear in a certain part of the screen.
some indecent stripes may also appear.
a special light or dark image will affect the adjacent display area.
in addition.
some fairly precise patterns (such as dithered images) may appear unsightly ripples or interference stripes on the LCD screen.
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now.
it is almost impossible Some LCDs used in notebook or desktop systems use thin film transistors (TFTs) to activate the cells in the liquid crystal layer.
TFT LCD technology can display more clear and bright images.
early LCDs are non active light emitting devices.
due to low speed, low efficiency and low contrast, although they can display clear text, they often produce shadows when they display images quickly, Nowadays, it is only used in palm computers, pagers or mobile phones that need black-and-white display.
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with the rapid development of technology,
LCD technology is also in continuous development and progress.
at present, major LCD manufacturers are increasing the R & D cost of LCD.
strive to break through the technical bottleneck of LCD, and further accelerate the industrialization process of LCD display Reduce production costs, (4) new technology of application and LCD.
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(1) TFT active elements are used for driving.
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in order to create better picture structure.
the new technology uses unique TFT active elements for driving.
we all know.
the most important part of the extremely complex LCD screen is liquid crystal Beyond the crystal,The backlight screen which is directly related to the brightness of the LCD and the color filter which is responsible for producing the color.
the active element is added to each LCD pixel for point-to-point control.
compared with the whole CRT display screen, the display precision of this control mode is much higher than that of the previous control mode, Therefore, poor image quality, color penetration and jitter will appear on CRT display screen, However, when viewed on the LCD screen with new technology, the picture quality is quite pleasing.
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(2) create a colorful picture by using the color filter manufacturing process.
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before the color filter body is made into shape.
dye the main material, This process requires a very high level of manufacturing.
however, compared with other ordinary LCD displays.
the LCD manufactured with this type of technology, no matter in terms of resolution, color characteristics or service life, (3) low reflection liquid crystal display technology.
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as we all know.
the external light has a great interference on the liquid crystal display screen. When the external light is strong, some LCD screens produce reflection because of the glass plate on their surface, However, it interferes with its normal display.
therefore, when it is used in some bright outdoor public places, its performance and observability will be greatly reduced.
at present, many LCD displays, even if the resolution is higher.
their reflection technology is not handled well, so it is not practical for practical work.
the application of LCD displays is not practicalWith some pure data,
in fact, it is a biased behavior to guide users.
the "low reflection liquid crystal display screen" technology adopted by the new LCD display is to apply ar coat on the outermost layer of the LCD screen.
with this layer of coating, the glossiness of the LCD screen, the light transmittance of the LCD screen itself, the The resolution and anti reflection of LCD screen have been improved better.
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(4) advanced "continuous boundary crystalline silicon" LCD display mode.
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in some LCD products.
there will be picture delay when watching motion pictures, This is due to the insufficient pixel response speed of the whole LCD screen.
in order to improve the pixel response speed.
the new technology LCD adopts the most advanced Si TFT LCD display mode, which has a pixel response speed 600 times faster than the old LCD screen, The effect is really different.
the advanced "continuous material boundary crystalline silicon" technology uses a special manufacturing method.
the original amorphous transparent silicon electrode is moved at a speed of 600 times the normal speed, which greatly speeds up the pixel reaction speed of the LCD screen and reduces the delay phenomenon of the picture.
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now.
low temperature polysilicon technology The research of reflective liquid crystal materials has entered the application stage, which will also make the development of LCD enter a new era.
with the continuous development of liquid crystal displays.
other flat panel displays are also in progress, such as plasma display panel (PDP), liquid crystal display (LCD) and so on The technology of electroluminescent array display (FED) and light-emitting polymer display (LEP) will set off a new wave of flat panel display in the future.
in this paper, the development trend of flat panel display is introducedHowever, it can be concluded that LCD technology has entered a new era, as another new force of display products, They are likely to replace CRT displays.
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go.
go http://www.yesky.com/Hardware/72624955006648320/20010625/186935.shtml.
Take a look.
I can't send some pictures.
resources: http://www.yesky.com/Hardware/72624955006648320/20010625/186935.shtml.
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