What is led display
Author:Gan Tingting Time:2021-06-07 17:59 Browse(865)
LED is light
LED is the abbreviation of light emitting diode, short for LED.

What is led display

it is a display mode by controlling semiconductor light emitting diode.
it is used to display text, graphics, images, animation, market, video, video signals and other information.
LED is a kind of display screenThe technological progress of LED is the biggest driving force to expand the market demand and application.
at the beginning.
LED was only used as a micro indicator light in high-end equipment such as computers, audio and video recorders. With the continuous progress of large-scale integrated circuits and computer technology, LED display is rising rapidly. In recent years, it has gradually expanded to stock market, stock machine, digital camera, video recorder, etc PDA and mobile phone field.
this paper introduces the development trend of PDA and mobile phone fieldLED display integrates microelectronic technology, computer technology and information processing.
with the advantages of bright color, wide dynamic range, high brightness, long service life, stable and reliable operation, it has become the most advantageous new generation of display media. At present, LED display has been widely used in large squares, commercial advertisements, stadiums, information dissemination, news release, securities trading, etc, It can meet the needs of different environments.
theStructure and classification of LED displayThrough proper connection (including series connection and parallel connection) and proper optical structure of LED chips,
the light-emitting segment or light-emitting point of light-emitting display can be formed.
from these light-emitting segments or light-emitting points, digital tube, symbol tube, meter tube, matrix tube, level display tube and so on can be formed.
generally, digital tube, symbol tube The meter tube is called the stroke display.
and the stroke display and the matrix tube are called the character display.
the meter tube is called the stroke display(1) LED display structureThe basic semiconductor nixie tube is composed of seven strip-shaped light-emitting diode chips arranged according to Fig. 12.
the structure of the LED chip is as follows:It can realize the display of 0-9.
its specific structures include "reflective hood", "strip seven segment" and "monolithic integrated multi bit digital"(1) The seven section shell with reflecting cavity is usually made of white plastic.
a single LED is pasted on the printed circuit board opposite to the seven reflecting cavities of the reflecting cover, and the center of the bottom of each reflecting cavity is the LED chip.
before installing the reflecting cover.
connect the chip and the corresponding metal strip on the printed circuit by pressure welding φ thirty μ Epoxy resin was dropped into the reflector, and then the printed circuit board with chip was aligned and bonded with the reflector, and then curedThere are two kinds of packaging methods for reflective cap type digital tube, namely, empty sealing and solid sealing.
the solid sealing method uses epoxy resin with scattering agent and dye.
it is mostly used for one position or two position devices.
the empty sealing method is to cover the filter and uniform film on the top.
in order to improve the reliability of the device, transparent insulating adhesive must be coated on the chip and the bottom plate, This can also improve the optical efficiency.
this method is generally used for digital display (or symbol display) with more than four digits.
this method can also improve the optical efficiency(2) The strip-shaped seven segment digital tube belongs to the mixed packaging form.
it is to divide the gallium phosphide or gallium phosphide wafer into one or several LED light-emitting strips, and then stick the same seven strips on the Japanese "Kovar" frame, connect the inner leads with the pressure welding process, and then wrap them with epoxy resin.
the chip is made of gallium phosphide or gallium phosphide wafer(3) The monolithic integrated multi bit digital display is based on the light-emitting material substrate (large wafer).
a large number of seven segment digital display graphics are produced by using the integrated circuit technology. The qualified chips are selected by scribing, and then pasted on the printed circuit board. The lead wire is drawn out by the pressure welding process, and then the "fisheye lens" shell is covered on the top.
the design of the single chip integrated multi bit digital display is introducedThey are suitable for small digital instruments(4) The production method of symbol tube and meter tube is similar to that of digital tube.
the production method of symbol tube and meter tube is similar to that of digital tube(5) The matrix transistor (LED lattice) can also be fabricated by a process similar to the monolithic integrated multi bit digital display(2) LED display classification(1) High score by word: the minimum word height of stroke display is 1 mm (the word height of monolithic integrated multi digit nixie tube is generally 2-3 mm).
other types of stroke display can reach 12.7 mm (0.5 inch) or even hundreds of mm(2) It can be divided into red, orange, yellow and green according to color(3) According to the structure, there are reflective hood type, single strip seven segment type and single chip integrated type(4) There are two kinds of electrode connection modes in each light emitting section: common anode and common cathode(3) Parameters of LED displaySince LED display is based on LED, its optical and electrical characteristics and limiting parameters are mostly the same as those of LED.
however, LED display contains multiple LEDs.
therefore, the following special parameters are required:1. Luminous intensity ratioBecause the forward current of each section of the nixie tube is not the same when the driving voltage is the same, the luminous intensity of each section is different.
the ratio of the maximum and minimum luminous intensity of all sections is the luminous intensity ratio.
the ratio can be between 1.5 and 2.3.
the maximum luminous intensity can not exceed 2.5.
the maximum luminous intensity of all sections can not exceed 2.52. Pulse forward currentIf the typical forward DC working current of each segment of stroke display is if.
under pulse, the forward current can be much larger than if.
the smaller the pulse duty cycle is.
the higher the pulse duty cycle isThe higher the pulse forward current can be.
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 and so on; 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 levelLED display screen is a display device composed of LED arrays.
it adopts low voltage scanning drive.
it has the following characteristics: low power consumption, long service life, low cost, high brightness, less 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 and buy LCD.
there are several basic indicators: high brightness: the higher the brightness value, the higher the brightness value, The screen is naturally more bright, and will not be foggy.
the unit of brightness is CD / m2.
that is, candlelight per square meter.
the brightness value of low-level LCD is as low as 150 CD / m2,High contrast: the higher the contrast, the more colorful and saturated the color, and the more stereoscopic it will appear.
on the contrary.
low contrast, the poorer the color, and the image will become flat.
the contrast value is quite different.
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, However, CRT display has no such problem.
the faster the signal response time is.
the more convenient the task processing is.
one of the methods of observation is to move the mouse quickly (that is, the mouse continuously downward indicates to the system.
the system continuously responds to the signal to the display),On ordinary low-level LCD displays, when the cursor moves rapidly, 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.
and the response time of ve500's super express signal is as fast as 16ms.
it allows the cursor to move without time difference, and the moving process is clear and easy to see, which does not bring work trouble.
in this way, the cursor can move without time difference
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