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Principles of industrial display monitor medical monitor repair maintenance repair ct display

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CRT Principles
Imaging the silver screen desktop monitors . Electron gun . Glass shell composition
The electron gun filament. Cathode. Gate . Accelerated pole. Focus pole. High voltage anode. Composition
The heating effect of the cathode filament of the cathode to emit electrons. Filament ends of plus 12 volt DC
The role of the cathode electron emission , the cylindrical shape of the top of the oxide coating is easy to emit electrons
. How much does it emit electrons shade - gate voltage. The higher the voltage , the electrons emitted
Small, low- emission , the more .
The gate is located in front of the cathode from the cathode ( approximately 0.1-0.2 ) in the middle to open holes for the electron transport
Move to provide access . The gate voltage level, can affect the number of electrons emitted by the cathode , if the gate
The higher the voltage , the electron conducive pull the cathode surface , the more electrons emitted by the cathode , trans
The less . The gate is generally grounded, so as long as you can control the level of the cathode voltage control electronics
The emission amount .
Accelerated pole located in front of the gate , the central open holes, generally add more than one hundred volts positive voltage,
Can accelerate electron accelerating voltage is higher, run faster electronics .
Focus very generally made larger diameter cylinder , plus the role of the coarse 0-400 volts electricity
Beam focused to a very fine electron beam , the more detailed , the picture becomes clearer.
Plus about 10 kV high voltage anode DC voltage ( commonly known as hypertension ) role is to further accelerate
Electron beams , high-speed electron beam bombardment on the phosphor screen . It is not introduced in the glass from the pin
The bridal veil cone open mouth ( high pressure nozzle ) is introduced . High voltage anode two parts, part located
In the neck , and the other part is connected to the aluminum film . Aluminum thin, high speed electrons easily
Through .
Glass enclosure includes a neck . Cone. Glass panel of three parts. Within the cone. Coated graphite conductive wall
Layer, the inner conductive layer is connected to the ultor outer conductive layer and the TV "ground " connected. So
About 500 picofarads to form a conductive layer between the inner and outer - the 1000 paper method of capacitance. As the anode voltage of the capacitor
Filter capacitor.
Screen wall painted about 10 microns thick so called phosphor screen .
LCD display principle
( A ) the physical properties of the liquid crystal

Physical properties of the liquid crystal is: When power is turned on , change the orderly arrangement , so that the light easily through ; arrangement confusion is not energized , preventing light to pass through . Let the liquid crystal such as camel barrier or gate to allow light to penetrate . Technically Briefly, the liquid crystal panel includes two relatively fine sodium glass material called Substrates, sandwiched between a layer of liquid crystal . When the light beam passes through this layer of liquid crystal , the crystal itself will stand in rows , or reverse the irregular shape, which block or pass the beam . Most LCD are all organic compounds , the molecular composition of a long rod . In the natural state, which is substantially parallel to the long axis of the rod-like molecules . The LCD into a slotted plane through sophisticated processing , the liquid crystal molecules are arranged along the groove , so if those slots are very parallel , each molecule is completely parallel.

Principle (b ) monochrome LCD display

LCD technology is poured into the liquid crystal between the two columns of the slot plane . Mutually perpendicular grooves on the two planes ( 90 intersect ) . That is , if the molecule to the north-south aligned on a plane , the other plane of the molecule to the arrangement of things , and is located between the planes of the two molecules are forced into a 90 -degree twisted state. Since the molecules are arranged along the propagation direction of the light , so the light through the LCD when it is twisted 90 degrees. But when a voltage is applied to the liquid crystal molecules will be re- arranged vertically , so that the light can be directed out, without any twisting .

LCD is dependent polarization filter ( film ) and the light itself . Natural light in all directions is random divergence . Polarizing filter is actually a series of increasingly fine parallel lines. These lines form a network, blocking all light and these lines are not parallel . The polarizing filter coincides with the first vertical line , it is possible to completely block the light that has been polarized . Only two completely parallel line filter , or the light itself has been reversed to a second polarizing filter to match the light was able to penetrate .

LCD is composed of two such mutually perpendicular polarizing filter , under normal circumstances, it should attempt to penetrate the block all light. However, since nematic liquid crystal is filled between the two filters , the light in the first filter after the piercing , is the liquid crystal molecules is twisted 90 degrees , and finally from the piercing of the second filter . On the other hand , when applying a voltage to the liquid crystal molecules will rearrange and completely parallel , so that light is no longer twisted , so that just the second filter is blocked . In short , power to block the light , no power will make the light emitted .

However , the LCD can change the liquid crystal alignment , so that the light emitted in the power , when the power is not blocked . However, as almost always on the computer screen , so only the " power- blocking the light ," the program in order to achieve the most energy purposes.

From a structural point of view LCD monitor , whether it is a laptop or desktop system, using the LCD screen is made of different parts of the hierarchy. LCD constituted by two glass plates , a thickness of 1mm, during which the liquid crystal containing a uniform 5μm (LC) material spaced intervals . Because the liquid crystal material itself is not light , so both sides have a display lamp as a light source , and in the back there is a backlit LCD display panel ( or even light board ) and the reflective film , backlit panels are composed of a fluorescent substance can emit light, its main function is to provide a uniform background light . Backlight emitted light after passing through the polarizing filter layer into the first layer comprises a liquid crystal layer thousands crystal droplets . Crystal droplets in the liquid crystal layer are included in the small cell structure, one or more cells constituting one pixel on the screen. Between the glass and the liquid crystal material is transparent electrodes is divided into row and column intersection , the row and column , the voltage is changed by changing the optical state of the liquid crystal , the liquid crystal material similar to the role of a small light valve. In the liquid crystal material to control the peripheral portion and the driver circuit is part of the circuit . When the electrodes generate an electric field in the LCD , the liquid crystal molecules is twisted so as to pass through one of the rules for refraction of light , then filtered through the filter layer, the second layer is displayed on the screen.

(C ) color LCD display works

For laptop or desktop LCD displays need to adopt a more sophisticated color displays, but also have to deal specifically with color display color filter layer . Typically , the color LCD panel, each pixel is constituted by the three liquid crystal cells , wherein each cell in front of the respective red, green , or blue filter. Thus, by the light of different cells in different colors can be displayed on the screen .

CRT LCD overcome the huge size, power consumption and flicker shortcomings, but they also bring the cost is too high, not wide viewing angle and color display is not ideal and other issues. A series of selectable resolution CRT display , and can be adjusted according to the requirements of the screen , LCD screen , but only the liquid crystal cell comprising a fixed number of only the use of a full screen display resolution ( each unit is a pixel ) .
Simple to understand is misseng as metaphor .

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