Document Type

Thesis

Date of Award

5-31-1988

Degree Name

Master of Science in Electrical Engineering - (M.S.)

Department

Electrical Engineering

First Advisor

Raj Pratap Misra

Second Advisor

Mauro Zambuto

Abstract

This thesis deals with the recent study of reliability of liquid crystal displays. This study determined the effects of high temperature on LCD reliability. To accomplish this, reliability life testing was done on different kinds of LCD samples under different operating conditions. The tests were carried out on the samples of two different vendors at two different temperatures. No humidity was added in any test.

Vendor No. 1

1. 120 units at 77° ± l° C.

2. 80 units at 85° ± 1° C.

Vendor No. 2

1. 60 hard and 60 soft glass units at 77° ± 1°C.

2. 40 hard and 40 soft glass units at 85° ± 1°C.

Data on units from start of life test every 1000 hours or 2000 hours is reported here in. Measurements were made when the units had stablized at room temperature. Leakage current was measured at 5.00 V D.C.

Generally it had been observed that the failure rate due to leakage current of samples of Vendor NO. 1 was high and the samples from Vendor No. 2 showed no failure. In general failure modes such as leakage current, peeling of seal, degradation of polarizers and segmental failure were observed in Vendor No. 1 under different rating of temperature. It was observed that most failures occured due to the distruction of molecular orientation with the penetration of moisture inside LCD.

Also it had been observed that improper sealing was a cause of failure in LCD's. Generally LCD's with hard glass end plates (borosilicate glass) showed less leakage current as compared to the LCD's with soft glass plates (sodalime glass), indicating their higher reliability.

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