Why can liquid crystal display?
Author:Liu Yanlan Time:2021-08-05 14:38 Browse(728)
Liquid crystal display
Liquid crystal display (LCD).

Why can liquid crystal display?

or liquid crystal display (LCD) is a flat and ultra-thin display device, which consists of a certain number of color or black-and-white pixels and is placed in front of the light source or reflector.
the power consumption of LCD is very low.
therefore, it is favored by engineers, Each pixel consists of the following parts: a column of liquid crystal molecules suspended between two transparent electrodes (indium tin oxide).
if there is no liquid crystal between two electrodes, light will be blocked by the other, The polarization direction of light passing through one filter is rotated by the liquid crystal, so that it can pass through another.
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the liquid crystal molecule itself has charge.
If a small amount of charge is added to the transparent electrode of each pixel or sub pixel, the liquid crystal molecule will be rotated by electrostatic force, and the light passing through will also be rotated, changing a certain angle, Before the charge is added to the transparent electrode.
the liquid crystal molecules are in an unconstrained state, and the charge on the molecules makes these molecules form a spiral or ring (crystal). In some LCDs, the chemical surface of the electrode can be used as the seed of the crystal, so the molecules crystallize according to the required angle, The light passing through one filter rotates after passing through the liquid chip, so that the light can pass through the other polarizer. A small part of the light is absorbed by the polarizer, but the rest of the devices are transparent.
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after the charge is added to the transparent electrode.
The liquid crystal molecules will be arranged along the direction of the electric field, thus limiting the rotation of the polarization direction of the light passing through. If the liquid crystal molecules are completely dispersed, the polarization direction of the light passing through will be completely perpendicular to the second polarizer, so it will be completely blocked by the light. At this time, the pixels will not emit light. By controlling the rotation direction of the liquid crystal in each pixel, we can control the light illuminating the pixels, More or less.
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many LCDs turn black under the action of alternating current.
alternating current destroys the spiral effect of the liquid crystal, and when the current is turned off, the LCD will become bright or transparent.
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in order to save power.
in the multiplexing mode, the electrodes at one end are connected in groups, and each group of electrodes is connected to a power supply, The electrodes at the other end are also connected in groups, and each group is connected to the other end of the power supply. The grouping design ensures that each pixel is controlled by an independent power supply. The electronic equipment or the software driving the electronic equipment controls the on / off sequence of the power supply, In order to control the pixel display.
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the indicators of LCD display include the following important aspects: display size.
reaction time (synchronization rate), array type (active and passive), viewing angle, supported color, brightness and contrast, resolution and aspect ratio of screen, And input interfaces (such as visual interface and video display array).
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brief history.
the first operable LCD is based on dynamic scattering mode.
a team led by George Hellman of RCA company developed this kind of LCD.
Hellman founded opal company.
this company developed a series of LCDs based on this technology.
this company has developed a series of LCDs based on this technologyIn December 1970,
the spin nematic field effect of liquid crystal was patented in Switzerland by the Central Laboratory of schent and herfrisch Hoffman lerock.
in 1969,
James fogson discovered the spin nematic field effect of liquid crystal at Ohio University, Ohio, USA, and registered the same patent in the United States in February 1971.
in 1971, his company (IL Ixco) produced the first LCD based on this characteristic.
soon replaced the DSM LCD with poor performance.
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display principle.
without voltage,
light will advance along the gap of liquid crystal molecules and turn 90 degrees, so light can pass through.
but with voltage,
light will advance along the gap of liquid crystal molecules, Therefore, the light is blocked by the filter.
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liquid crystal is a material with flowing characteristics.
therefore, only a very small force is needed to make the liquid crystal molecules move. Take the most common nematic liquid crystal as an example, the liquid crystal molecules can easily make the liquid crystal molecules turn by the action of electric field. Because the optical axis of the liquid crystal is quite consistent with its molecular axis, it can produce optical effect, When the electric field applied to the liquid crystal is removed and disappeared, the liquid crystal will return to its original state very quickly by virtue of its elasticity and viscosity.
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transmission and reflection display.
LCD can transmit display.
also can reflect display, It depends on where the light source is placed.
transmission LCD is illuminated by the light source on the back of one screen.
while viewing is on the other side of the screen (front).
this type of LCD is often used in applications requiring high brightness display.
this type of LCD is mainly used in applications requiring high brightness displayFor example, in computer monitors, PDAs and mobile phones.
the power consumption of lighting devices used to illuminate LCDs is often higher than that of LCDs themselves.
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reflective LCDs are commonly used in electronic clocks and computers, and (sometimes) the external light is reflected back to illuminate the screen by the backscattered reflecting surface.
this type of LCD has high contrast.
because the light has to pass through the LCD twice, So it was cut twice.
without lighting, the power consumption was significantly reduced.
therefore, the batteries of devices using batteries were used longer.
because the power consumption of small reflective LCD was very low.
even the photocell was enough to power it, Therefore, it is commonly used in pocket calculators.
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semi penetrating reflective LCD can be used as transmission type.
it can also be used as reflection type.
when the external light is sufficient.
the LCD works as reflection type, and when the external light is insufficient, it can be used as transmission type.
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color display.
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in color LCD,
each pixel is divided into three units, Or subpixel, with additional filters marked in red, Green and blue.
the three sub pixels can be controlled independently.
the corresponding pixels produce thousands or even millions of colors.
the old CRT uses the same method to display colors.
according to the needs.
color components are arranged according to different pixel geometry principles.
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common LCD point distance.
common LCD point distance table:
12.1 Inch (800 × 600) - 0.308 mm.
12.1 in (1024 × 240 mm.
014.1 in. (1024 × 768) - 0.279 mm.
14.1 in (1400 mm) × 1050) - 0.204 mm.
15 inches (1024 × 768) - 0.297 mm.
15 inches (1400 mm) × 1050) - 0.218 mm.
15 inches (1600 mm) × 1200) - 0.190 mm.
16 inches (1280 mm) × 1024) - 0.248 mm.
17 inches (1280 mm) × 1024) - 0.264 mm.
17 inch widescreen (1280 mm) × 768) - 0.2895 mm.
17.4 in (1280.5 mm) × 1024) - 0.27 mm.
18 inches (1280 × 1024) - 0.281 mm.
19 inches (1280 × 1024) - 0.294 mm.
19 inches (1600 mm) × 1 200) - 0.242 mm.
19 inch widescreen (1440 × 900) - 0.283 mm.
19 inch widescreen (1680 mm) × 1050) - 0.243 mm.
20 inch wide screen (1680 mm) × 1050) - 0.258 mm.
20.1 inch (1200 mm) × 1024) - 0.312 mm.
20.1 in. (1600 mm) × 1200) - 0.255 mm.
20.1 in. (2560 × 2048) - 0.156 mm.
20.8 in. (2048) × 207 mm.
021.3 in. (1600 × 1200) - 0.27 mm.
21.3 in (2048 × 1536) - 0.21 mm.
22 inch widescreen (1600 × 1024) - 0.294 mm.
22.2 in (3840 × 2400) - 0.1245mm.
23 inch wide screen (1920 × 1200) - 0.258 mm.
23.1 in. (1600) × 1200) - 0.294 mm.
24 inch wide screen (1920 × 1200) - 0.27 mm.
26 inch widescreen (1920 ×
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it's not only 20 inch LCD.
most of the 17 inch, 23 inch and 24 inch LCD displays have the problem of too small text.
the displays suitable for Internet access and word processing include 15 inch, 19 inch, 19 inch, 22 inch and 26 inch LCD screens.
their point spacing is large, The size of the text display is appropriate.
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the LCD is a special liquid.
it has good fluidity and high definition, giving people a real feeling.
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the LCD is a special liquid
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