What is led? What's the difference between LCD and LCD?
Author:Xu Jian Time:2021-06-11 08:02 Browse(143)
LED applications can be divided into two categories:
LED applications can be divided into two categories: first, LED single tube applications, including backlight LED, infrared LED, etc; 2、 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.

What is led? What's the difference between LCD and LCD?

in this paper, the design and production technology of LED display in China are introducedThe LED display screen is a display device composed of LED arrays.
it adopts low voltage scanning drive.
it has the following advantages: 1. Low power consumption and long service life; 2. Low cost and high brightness; 3. It has the characteristics of few faults, large viewing angle and long visual distance.
the system has the advantages of high reliability, low cost and low costThe 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: 1. The arrangement becomes orderly when power is on.
it makes light lines easy to pass through; 2. The advantages of LCD are as follows: 1. 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.
2 Choose and buy LCD.
there are several basic indicators: high brightness: the higher the brightness value is, the brighter the picture will be, and there will be no haze.
the unit of brightness is CD / m2.
that is, the candlelight per square meter.
the LCD has several basic indicatorsThe 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.
3. High contrast: the higher the contrast is.
the brighter the color is, the more saturated it will be, and the more stereoscopic it will be.
on the contrary.
with low contrast, the color will be poor, and the image will become flat.
the difference of contrast value is quite large.
as low as 100:1, and as high as 600:1, or even higher.
4 Broad visual range: the visual range refers to the clear range that can be seen in front of the screen.
the larger the visual range is.
naturally, it is easier to see; 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, while CRT traditional CRT displays have no such problem.
the faster the signal response time is.
the faster the signal response time isThe more convenient job 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). On the general low-level LCD display, the cursor will disappear when it moves quickly, and it will not appear again until the mouse is positioned and no longer moved 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 applied.
in the same year, Toshiba developed ingaa1p 573Nm yellow green ultra-high brightness LED, The normal light intensity is up to 2CD.
in 1994, the InGaN 450nm blue (green) ultra-high brightness LED was developed by Japan Asia company.
so far.
the three primary colors of red, green, blue, orange and yellow required for color display have reached candela level luminous intensity,It has realized ultra-high brightness and full-color, making 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, so as to realize three-dimensional animation.
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 color1、 Design principle of outdoor screen systemStructural design principlesBrightness and color matching basisReliability design principleSafety design principleDesign principle of easy management and operability2、 Screen 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, The back-end is the electronic display unit.
the 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 buffer 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 / gray processing subsystem receives 24 bits true color signals from super five twisted pair cables.
the weights are 20, 21, 22, 23, 24, 25, 26, 27 respectively,Each primary color has eight weight components, which are controlled by CPLD to achieve 256 level gray control signal.
anti interference processing is carried out in the video receiving circuit, storage circuit, high speed writing circuit, and display screen control scanning circuit.
and the display screen refresh frequency is 150Hz, which has strong stability and real-time performance, and ensures real 24 bit true color effect. 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 Correction.
after correction, the chromaticity space will be significantly improved.
corresponding to the LED large screen.
the physical brightness is directly proportional to the gray value. If not corrected, it can not meet the requirements of color restoration. Specifically, the display effect is: the low gray level jumps greatly, while the high gray level cannot be distinguished clearly.
as we all know.
the perception of light intensity by human eyes is nonlinear, When the light intensity is doubled, 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 the human eye is less than doubled. Therefore, it is necessary to make a nonlinear transformation of the gray level, so that the time interval is small when the gray level is low, and large when the gray level is high.
in this way, the gray level can be transformed into a non-linear transformationTherefore, in order to ensure the complete restoration of LED large screen color,
it is necessary to carry out anti gamma correction. After correction, its characteristics are similar to those of CRT.
we can clearly see that.
after gray correction, the display screen will appear clear texture, strong sense of hierarchy, soft brightness and smooth transition between light and dark.
true color screen white balance The technical guarantee of color deviation and color richness white balance refers to when each primary color reaches the highest level of brightness.
the white color deviation at 6500k is a phenomenon that the brightness of LED, especially red LED, changes with temperature.
the existence of color deviation indicates a production debugging process at a specific temperature When the display reaches white balance, it will lose balance with the change of working temperature, 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 the true color display screen.
it can effectively ensure the color richness and consistency of the true color display screen.
our company has a comprehensive solution to the problem caused by the color deviation of the true color display screenIntelligent monitoring and protection systemThe intelligent monitoring system consists of all kinds of sensors, monitoring system and control computer.
it is used to monitor the working environment parameters of the display screen, timely control the relevant protection system, ensure the normal operation of the display screen, and ensure that the performance parameters do not deviate greatly.
the protection system includes: heat dissipation system, waterproof system, power distribution system, lightning protection system, etc.
the intelligent monitoring system is composed of all kinds of sensors, monitoring system and control computerControl softwareThe normal operation of the display system.
the display system is in good conditionIt needs the support of related software.
our software designers have created a powerful and easy-to-use software configuration system through careful preparation and combination.
in this software system, we classify them into two categories according to the different functions of software: one is display control software, which mainly completes the playback and switching control of text, animation and video images, They are the basic software of display screen; The other is content editing software, which is mainly used for creative production and graphic editing, which can constantly update and transform the display content.
LED is the abbreviation of light emitting diode.
LED applications can be divided into two categories: one is led single tube applications.
including backlight LED, infrared LED, etc; 2、 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.
in this paper, the design and production technology of LED display in China are introducedThe LED display screen is a display device composed of LED arrays.
it adopts low voltage scanning drive.
it has the following advantages: 1. Low power consumption and long service life; 2. Low cost and high brightness; 3. It has the characteristics of few faults, large viewing angle and long visual distance.
the system has the advantages of high reliability, low cost and low costThe 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 properties of liquid crystal: 1Make light easy to pass through; 2. The advantages of LCD are as follows: 1. 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.
2 Choose and buy LCD.
there are several basic indicators: high brightness: the higher the brightness value is, the brighter the picture will be, and there will be no haze.
the unit of brightness is CD / m2.
that is, candlelight per square meter.
low level LCD brightness value is as low as 150 CD / m2, while high-level display can be as high as 250 CD / m2.
3. High contrast: the higher the contrast is.
the more colorful and saturated, On the contrary,
the contrast is low, the color is poor, and the image will become flat.
the contrast value is quite different.
there are as low as 100:1, or as high as 600:1, or even higher.
4. Wide visual range: in short,
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 wider the range is, but the range of the four directions is not necessarily symmetrical.
when the upper, lower, left and right directions are symmetrical.
when the upper, lower, left and right directions are symmetricalSome 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). On a low-level LCD display, the cursor will disappear when it moves quickly, Until the mouse positioning, no longer move after a short period of time, will appear again; 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.
the 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 performance level that conventional materials such as GaAlAs, GaAsP and gap can not achieve.
the research and development of high brightness a1gainp and InGaN LED is very rapidIn 1991, + + Toshiba and HP developed ingaa1p 620nm orange ultra-high brightness LED.
in 1992, ingaa1p590nm yellow ultra-high brightness LED was applied.
in the same year,
Toshiba developed ingaa1p 573Nm yellow green ultra-high brightness LED, The normal light intensity is up to 2CD.
in 1994, the InGaN 450nm blue (green) ultra-high brightness LED was developed by Japan Asia company.
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 use LED color large screen to show the sky and ocean, and realize three-dimensional animation.
the new generation of red, green and blue ultra-high brightness LED has achieved unprecedented performance.
this paper introduces a new generation of red, green and blue ultra-high brightness LEDAt 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 color1、 Design principle of outdoor screen systemStructural design principlesBrightness and color matching basisReliability design principleSafety design principleDesign principle of easy management and operability2、 Screen installation modeΔ wall mounted: that is, the display screen is back to the wall.
the display screen is wall mountedAnd fixed on the wall.
this method is a common way.
and it is easy to realize.
this method is easy to realizeDelta 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, The back-end is the electronic display unit.
the 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 buffer 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 channel of super class 5 twisted pair,
the super class 5 twisted pair realizes the connection between the acquisition / sending subsystem and the receiving / gray processing subsystem.
the signal transmission is completed.
without relay.
the data transmission is completedThe longest transmission distance can reach 300 meters.
the maximum transmission distance can reach 300 metersGray 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 physical brightness is proportional to the gray value,If it is not corrected, it obviously can not meet the requirements of color restoration, specifically in the display effect is: the low-level gray jump is very big, and the high-level gray is not clear.
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 after gray correction will appear clear texture, strong sense of hierarchy, soft brightness and smooth transition between light and dark.
true color screen white balance The technical guarantee of color deviation and color richness white balance refers to when each primary color reaches the highest level of brightness.
the white color deviation at 6500k is a phenomenon that the brightness of LED, especially red LED, changes with temperature.
the existence of color deviation indicates a production debugging process at a specific temperature When the display reaches white balance, it will lose balance with the change of working temperature, 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 the true color display screen.
it can effectively ensure the color richness and consistency of the true color display screen.
our company has a comprehensive solution to the problem caused by the color deviation of the true color display screenIntelligent monitoring and protection systemThe intelligent monitoring system consists of various sensors, monitoring system and control computerIt is used to monitor the working environment parameters of the display screen, timely control the relevant protection system, and ensure the normal operation of the display screen, without large deviation of performance parameters.
the protection system includes: heat dissipation system, waterproof system, power distribution system, lightning protection system, etc.
it is used to monitor the working environment parameters of the display screen, timely control the relevant protection system, and ensure the normal operation of the display screenControl softwareThe 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. They can constantly update and transform the display content.
.
one is SD, the other is Hd! The resolution is also different
.
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