LED测试及控制的自动化.PDF

Automated LED Testing and Control LED 測試與控制的自動化測試與控制的自動化 測試與控制的自動化測試與控制的自動化 作者 (David Johnson, Cypress Semiconductor Corp.) Executive Summary Light Emitting Diodes (LEDs) are used in most applications. The problem is that unlike most modern ICs there is not a simple way to test in manufacturing that they have been assembled properly. The majority of system manufacturers test LEDs by visual inspection. This is highly prone to error since it is entirely dependent on the individual operator to detect the failure in a highly repetitive environment. These primary failures manifest as opens or shorts and can be tested automatically through electrical measurements of the actual LED. A basic method for electrical testing will be described showing how discrete components can be used to take voltage measurements across an energized LED and then used to determine if it is electrically “good”. Basically this will take a voltage measurement across an energized LED and compare it against a “good” value to determine any problem LEDs. The primary limitation of this approach is the component count which is required to implement the design for high LED count boards. This article will illustrate how to automate testing of LEDs under multiple configurations, including an approach requiring only a single component testing multiple LEDs without requiring additional discrete elements. This provides designers with the capability to not only automate the testing of LEDs, but also test at any time simply by repeating the measurements. 發光二極體(LED)常被用於各種現代電子設計與系統中 ，以提供影像顯示與狀態檢視的功能。在機板日趨 複雜之際 ，廠商紛紛尋求更多的測試功能 ，來檢驗每個元件。而這將會使得邊界掃瞄測試(Boundary Scan Test, BST)演進到加入具備完整功能的內建自我測試(Build-in Self Test, BIST)技術。業者面臨的挑 戰在於至今仍有一些元件的自動測試功能有限 ，必須依賴人工測試或目測來偵測故障狀況。這類 LED 可 製造出 1 美元成本的零組件 ，應用在售價達 1 萬美元的線路卡或系統中 ，因此，零組件品質的優劣會直 接影響顧客滿意度 ，以及他們對整體產品品質的觀