Ask professionals, the difference between LED screen and LCD screen?
Author:Chen Hong Time:2021-06-08 13:35 Browse(790)
LED is light emitting diode
LED is the abbreviation of light emitting diodeLED applications can be divided into two categories: one is led single tube applications.
including backlight LED, infrared LED, etc; At present, there is still a certain gap between China and the world in the manufacturing of LED basic materials, but as far as LED display is concerned, China's design and production technology level is basically in line with the international level.

Ask professionals, the difference between LED screen and LCD screen?

in addition, there is a gap between China and the world in the manufacturing of LED basic materialsLED display is a display device composed of LED arrays.
it is driven by low voltage scanning.
it has the following characteristics: low power consumption, long service life, low cost, high brightness, few faults, large viewing angle, long viewing distance, etc.
it has the advantages of low power consumption, long service life, low cost, high brightness, less faults, long viewing distance, etcThe original text of LCD is liquid crystal display.
it is composed of the first letter of each word, which is often called "liquid crystal flat panel display" or "liquid crystal display" in Chinese.
its working principle is to make use of the physical characteristics of liquid crystal: the arrangement becomes orderly when power is on.
it makes light easy to pass through; The advantages of LCD are: compared with CRT display.
the advantages of LCD mainly include zero radiation, low power consumption, small heat dissipation, small volume, accurate image restoration, sharp character display, etc.
choose LCD.
there are several basic indicators: high brightness: the higher the brightness value, the higher the brightness value, The brightness unit is CD / m2.
that is, candlelight per square meter.
the brightness value of low-level LCD is as low as 150 CD / m2, while that of high-level display is as high as 250 CD / m2.
the brightness value of low-level LCD is as low as 150 CD / m2High contrast: the higher the contrast is.
the brighter the color is, the more saturated it will be, and the more three-dimensional it will be.
on the contrary.
if the contrast is low, the color will be poor, and the image will become flat.
the contrast value is quite different.
there are as low as 100:1 and as high as 600:1, Even higher.
wide visual range: simply speaking,
refers to the clear range that can be seen in front of the screen.
the larger the visual range, the easier it will be; The smaller the value is, the clearer the picture will be if the viewer changes the viewing position a little.
the algorithm of visual range is from the middle of the picture.
the clear angle range of the picture is from the top, bottom, left and right directions.
the larger the value is.
the wider the range is naturally, but the range of the four directions is not necessarily symmetrical.
some manufacturers will add the angle values on both sides and mark them as horizontal: 160 °; Vertical: 160 °; It may also be labeled left / right separately: ± eighty °; Up / down: ± eighty °. signal response is very important for animation and mouse movement.
generally speaking, this phenomenon only occurs on LCD, The faster the signal response time is, the more convenient the task processing is.
one of the ways to observe is to move the mouse quickly (that is, the mouse keeps moving down to indicate to the system.
the system keeps responding to the signal to the display),When the cursor moves quickly, it will disappear in the process. It will not appear again until the mouse is positioned and no longer moves for a short period of time; When moving at normal speed, you can also see the trace of mouse movement clearly.
while the response time of ve500's ultrafast signal is as fast as 16ms.
it makes the cursor move without time difference, and the moving process is clear and easy to see, which does not bring any work trouble.
this paper introduces a method of moving the cursor at normal speedCharacteristics of LEDUltra high brightness materials should be used in LED.
brightness height (uhB) refers to the LED whose luminous intensity reaches or exceeds 100mcd, also known as candela (CD) led.
the development of high brightness a1gainp and InGaN LED is very rapid.
it has reached the standard of conventional materials GaAlAs, GaAsP, InGaN led In 1991, Toshiba and HP developed ingaa1p 620nm orange ultra-high brightness LED.
in 1992, ingaa1p590nm yellow ultra-high brightness LED was put into practice.
in the same year, Toshiba developed ingaa1p 573Nm yellow green ultra-high brightness LED, The normal light intensity is up to 2CD.
in 1994, Japan Nippon Yat Sen company developed InGaN 450nm blue (green) ultra-high brightness LED.
so far.
the three primary colors of red, green, blue, orange and yellow LED for color display have reached candela level luminous intensity, realizing ultra-high brightness and full color, It makes the outdoor full-color display of LED become a reality.
the luminous brightness has been higher than 1000mcd.
it can meet the needs of outdoor all-weather and full-color display, and the sky and ocean can be represented by LED color large screen,Three dimensional animation is realized.
the new generation of red, green and blue ultra-high brightness LED has achieved unprecedented performance.
the new generation of red, green and blue ultra-high brightness LED has achieved unprecedented performanceAt present, the outdoor screen pixels are composed of several single LED tubes of red / Green / blue primary colors.
the commonly used finished products are pixel tube and pixel module.
the pixel size is mostly 12-26mm.
the pixels are composed of: 2R / 3R / 4R for monochrome, 1r2yg / 1r3yg / 1r4yg for pseudo color and 2R1G1B for true colorDesign principle of outdoor screen systemStructural design principlesBrightness and color matching basisReliability design principleSafety design principleDesign principle of easy management and operabilityScreen installation modeΔ wall mounted: that is, the display screen is back to the wall.
and fixed on the wall.
this is a common way.
and the calibration is easy to realize.
this method is simple to useDelta vertical: that is, the display screen is sitting on the platform.
this mode is the easiest to realize.
this installation mode should be preferred when conditions permitDelta inlay: that is, the display screen is inlaid in a wall frame.
this method is rare.
if the concave depth of the wall is not enough, its maintainability should be considered.
if the concave depth of the wall is not enoughΔ side hanging type: the display screen is stressed on both sides.
it is hung between two buildings or columns.
this method is often used for hanging the screen in open space.
the two columns are built according to the hanging requirements of the screen.
the display screen is suspended in open spaceDisplay control systemDacheng display control system is composed of acquisition / sending subsystem and receiving / gray processing subsystem.
its front end is VGA feature output interface of computer or multimedia card with digital component output, and its transmission is realized by CATV twisted pair, and its back end is electronic display unit.
Dacheng display control system is composed of acquisition / sending subsystem and receiving / gray processing subsystemThe acquisition / transmission subsystem collects 24 bits true color signals at a frame rate of no less than 60 frames per second.
and writes them into the built-in display cache smoothly in the way of dual memory alternate operation, and completes the gray weight conversion under the control of the central processing unit, Through LVDS differential to the super five twisted pair channel.
the super five twisted pair realizes the connection between the acquisition / sending subsystem and the receiving / gray processing subsystem.
the signal transmission is completed.
without relay.
the longest transmission distance can reach 300 meters.
the transmission of the super five twisted pair is realizedGray level realization descriptionDacheng receiving / grayscale processing subsystem receives 24 bits true color signals from super five twisted pair cables.
the weights are 20, 21, 22, memory 23, 24, 25, 26 and 27 respectively, and each primary color has eight weight components, which are controlled by CPLD to realize 256 level grayscale control signals.
in the video receiving circuit, storage circuit, high-speed writing circuit, high-speed writing circuit, high-speed writing circuit, high-speed writing circuit, high-speed recording circuit, high-speed recording circuit, high-speed recording circuit, high-speed recording circuit, high-speed recording circuit, high-speed The anti-interference processing is carried out in the display screen control scanning circuit.
and the display screen refresh frequency is 150Hz, so it has strong stability and real-time performance, and ensures the real 24 bit true color effect.
the display screen control scanning circuit has high stability and real-time performanceThe number of colors that can be produced by different combination of 256 gray levels of red, green and blue is 256 × two hundred and fifty-six × 256=16777216 colors (i.e. 16m colors)Nonlinearity γ correctingThe video signal is designed to meet the luminous and electrical characteristics of TV.
it can be played on TV or monitor.
if the TV signal is not corrected, serious color distortion will occur.
therefore, the front end of the input video signal must be non-linear γ After correction, the chromaticity space will be significantly improved.
corresponding to the LED large screen.
the color space of LED large screen will be improvedThe physical brightness is directly proportional to the gray value. If it is not corrected, it obviously can not meet the requirements of color restoration. The specific display effect is: the low-level gray jump is very big, and the high-level gray can not be distinguished clearly.
as we all know.
the perception of light intensity by human eyes is nonlinear. When the light is weak, the light intensity is doubled, and the enhancement felt by human eyes is more than doubled; When the light intensity is strong, the light intensity is doubled, and the enhancement felt by human eyes is less than doubled. Therefore, it is necessary to make nonlinear transformation of gray level, so that the time interval is small when the gray level is low, and the time interval is large when the gray level is high.
therefore, in order to ensure the complete restoration of LED large screen color.
anti gamma correction must be carried out, We can clearly see that the display screen after gray correction will appear clear texture, strong sense of hierarchy, soft brightness and smooth transition between light and dark.
Technical guarantee for white balance, color deviation and color richness of true color screenWhite balance refers to when each primary color reaches the highest level of brightness.
the white color deviation of 6500k is a phenomenon that the brightness of LED, especially red LED, changes with temperature.
the existence of color deviation indicates that a display screen with white balance can be produced and debugged at a specific temperature, With the change of working temperature, it will lose balance, or because of the uneven temperature distribution in the screen, the whole display screen will appear "Hualian" phenomenon after playing for a period of time.
our company has a comprehensive solution to the problem caused by the color deviation of true color display screen.
it can effectively ensure the color richness and consistency of true color display screenIntelligent monitoring and protection systemThe intelligent monitoring system is composed of various sensors, monitoring system and control computer.
it is used to monitor the working environment parameters of the display screen,The relevant protection system should be timely controlled to ensure that the display screen works normally and the performance parameters do not deviate greatly.
the protection system includes: heat dissipation system, waterproof system, power distribution system, lightning protection system, etc.
the protection system is composed of three partscontrol software The normal operation of the display system requires the support of relevant software.
our company's software designers have created a powerful and easy-to-use software configuration system through careful preparation and combination.
in this software system.
according to the different functions of the software, we classify them into two categories: one is the display control software, which mainly completes the text, the other is the display control software Animation and video image play and switch control, they are the basic software of the screen work; The other is content editing software, which is mainly used for creative production and graphic editing, and can constantly update and transform the display content of the display screen.
the first type is content editing softwareLCD is divided into STN, TFT, TFD, etc1. What is STN?STN (super twisted nematic) is to change the arrangement of liquid crystal molecules twisted by more than 180 degrees with electric field, so as to change the optical rotation state.
the applied electric field changes the electric field by scanning line by line. In the process of electric field changing the voltage repeatedly, the recovery process of each point is slow, The two biggest differences between STN and TFT are that the performance of TFT is better than that of STN.
however, STN saves more power than TFT.
the results show that STN is more efficient than TFT2. What is TFT?TFT (thin film transistor) refers to thin film transistor.
it means that each liquid crystal pixel is driven by a thin film transistor integrated behind the pixel, which can display screen information with high speed, high brightness and high contrast. It is one of the best LCD color display devices at present,Its effect is close to CRT display, and it is the mainstream display device on notebook computers and desktop computers.
every pixel of TFT is controlled by the TFT integrated on itself.
it is an active pixel.
therefore.
not only the speed can be greatly improved, but also the contrast and brightness can be greatly improved, and the resolution can also reach a very high level.
in this paper, the design of TFT is introduced3. What is TFD?The progress of mobile phones continues.
in this case, people have higher requirements for LCD performance. The following are the important performance characteristics of color LCD for mobile phones in the future: (1) high image quality; 2) Low power consumption( 3) Be able to process active images; 4) Compact structure; Epson has been commercializing an active dot matrix lcd-d-tfd (Digital thin film diode) and has become one of the leading manufacturers of digital cameras.
one of the important reasons is that low power consumption (the characteristics of d-tfd) and high image quality / high response speed (the characteristics of active dot matrix LCD) meet the requirements of digital cameras.
by integrating high image quality, low power consumption (the characteristics of d-tfd) and high image quality / high response speed (the characteristics of active dot matrix LCD) The new technology of low power consumption and more compact structure has been applied to this kind of d-tfd.
we have achieved the above four requirements for the next generation mobile phone at a high level.
this kind of LCD is called "md-tfd"
in this paper, we introduce the new technology of low power consumption and more compact structure4. What is the difference between TFT, STN and TFD LCD?There are STN mode, TFD mode and TFT mode for mobile phones.
the TFT mode has the best image quality.
most of the displays used in notebook computers are of this type.
however, although the TFT has a beautiful picture,
it consumes a lot of power, so it has the disadvantage of not durable battery for mobile phones.
in this paper, the design of TFT is introducedAlthough STN has the worst image quality,
it has the advantages of low power consumption and low cost.
TFD is just located in the middle of TFT and STN.
although the image quality is slightly inferior to TFT.
but the power consumption is less than TFT.
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STN has the advantages of low power consumption and low cost
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