【正文】 m、Φ 16mm、Φ 19mm、Φ 20mm、Φ 21mm、Φ 22mm、Φ 26mm 。雙基色顯示屏：紅和綠雙基色， 256 級灰度、可以顯示 65536 種顏色。 LED 顯示屏分為圖文顯示屏和視頻顯示屏，均由 LED 矩陣塊組成。藍(lán)光 LED 基片安裝在碗形反射腔中，覆蓋以混有 YAG 的樹脂薄層，約 200500nm。以 12 英寸的紅色交通信號燈為例，在美國本來是采用長壽命、低光效的 140 瓦白熾燈作為光源，它產(chǎn)生 2020 流明的白光。 LED 歷 史 50 年前人們已經(jīng)了解半導(dǎo)體材料可產(chǎn)生光線的基本知識，第一個商用二極管產(chǎn)生于 1960 年。s and other public places. The LED display can display the change of digital image。但這兩種半導(dǎo)體連接起來的時候，它們之間就形成一個“ PN 結(jié)”。這種利用注入式電致發(fā)光原理制作的二極管叫發(fā)光二極管，通稱 LED。 1998 年白光的 LED 開發(fā)成功。當(dāng) 時研制的 LED，所用的材料是 GaASP，其發(fā)光顏色為紅色。這些優(yōu)點概括起來是：亮度高、工作電壓低、功耗小、小型化、壽命長、耐沖 擊和性能穩(wěn)定。 按使用場合分類，室內(nèi)顯示屏：發(fā)光點較小，一般Φ 3mmΦ 8mm，顯示面積一般幾至十幾平方米。 LED 顯示屏檢驗方法，一看屏體規(guī)格，外觀，平整度，屏內(nèi)的連線等。 缺點： 混色效果不佳，視角不大，水平方向左右觀看有色差。另外， AT89C52 可降至 0Hz靜態(tài)邏輯操作，支持 2 種軟件可選擇節(jié)電模式。 ALE/ PROG ： 地址鎖存控制信號（ ALE）是訪問外部程序存儲器時，鎖存低 8 位地址的輸出脈沖。 PSEN :外部程序存儲器選通信號（ PSEN ）是外部程序存儲器選通信號。 存儲器結(jié)構(gòu) :MCS51器件有單獨的程序存儲器和數(shù)據(jù)存儲器。對于 AT89C52， 。然而，定時器 2的標(biāo)志位 TF2在計數(shù)溢出的那個周期的S2P2被置位，在同一個周期被電路捕捉下來。它們?yōu)?AT89系列新產(chǎn)品預(yù)留。 程序存儲器： 如果 EA 引腳接地，程序讀取只從外部存儲器開始。 EA /VPP:訪問外部程序存儲器控制信號。 在一般情況下， ALE 以晶振六分之一的固定頻率輸出脈沖，可用來作為外部定時器或時鐘使用。掉電保護方式下， RAM 內(nèi)容被保存，振蕩器被凍結(jié)，單片機一切工作停止，直到下一個中斷或硬件復(fù)位為止。實際像素分辨率做到 10000 點以上較難。 技術(shù)優(yōu)勢評述。 按發(fā)光點直徑分類，室內(nèi)屏：Φ 3mm、Φ 、Φ 5mm。 LED 顯示屏的分類 按顏色基色可以分為 ，單基色顯示屏 :單一顏色（紅色或綠色）。然而照明需用的白色光 LED 僅在近年才發(fā)展起來，這里向讀者介紹有關(guān)照明用白光。 GaN 芯片發(fā)藍(lán)光（λ p=465nm，Wd=30nm），高溫?zé)Y(jié)制成的含 Ce3+的 YAG 熒光粉受此藍(lán)光激發(fā)后發(fā)出黃 色光射，峰值550nm。 最初 LED 用作儀器儀表的指示光源，后來各種光色的 LED 在交通信號燈和大面積顯示屏中得到了廣泛應(yīng)用，產(chǎn)生了很好的經(jīng)濟效益和社會效益。而光的波長也就是光的顏色，是由形成 PN結(jié)的材料決定的。 1 Based on AT89C52 LED overview LED (Light Emitting Diode), lightemitting diode, is a solid state semiconductor devices, which can be directly converted into electricity to light. LED is the heart of a semiconductor chip, the chip is attached to one end of a stent, is the negative side, the other end of the power of the cathode, the entire chip package to be epoxy resin. Semiconductor chip is posed of two parts, part of the Ptype semiconductor, it inside the holedominated, the other side is the Ntype semiconductor, here is mainly electronic. But linking the two semiconductors, among them the formation of a PN junction. When the current through the wires role in this chip, will be pushing eP, P zone in the hole with electronic posite, and then to be issued in the form of photon energy, and this is the principle of LED luminescence. The wavelength of light that is the color of light, is formed by the PN junction of the decisions of the material. LED history 50 years ago, people have to understand semiconductor materials can produce light of the basic knowledge, the first mercial diodes in 1960. English is the LED light emitting diode (LED) acronym, and its basic structure is an electroluminescent semiconductor materials, placed in a wire rack, then sealed with epoxy resin around, that is, solid package, Therefore, the protection of the internal batteries can play the role of line, so the seismic performance LED good. LED is the core of the Ptype semiconductor and ponents of the Ntype semiconductor chips, the Ptype semiconductor and Ntype semiconductor between a transition layer, called the PN junction. In some semiconductor materials in the PN junction, the injection of a small number of carriercarrier and the majority of the extra time will be in the form of light energy to release, thus the power to direct conversion of solar energy. PN junction on reverse voltage, a few hardcarrier injection, it is not luminous. This use of injection electroluminescent diodes is produced by the principle of lightemitting diodes, monly known as LED. When it in a positive state of the work (that is, at both ends with forward voltage), the current flows from the LED anode, cathode, semiconductor crystals on the issue from the ultraviolet to infrared light of different colors, light a