Infrared thermography as evaluation method of a faulty status of a LED LCD TV

Abstract

The paper presents the application of infrared thermography in the detection of anomalies (hotspots) that may lead to defects of the backlight unit, which are not yet noticeable in the visible part of the electromagnetic spectrum. It is shown on a practical example of an LED LCD TV how hotspots at the maximum level of brightness led to the failure of one element of the LED backlight segments in 2 years time. Once the faulty element was detected, brightness was reduced in order to preserve the remaining LED elements. Infrared thermographic analysis of the faulty state was repeated and compared with measurements of photometric values. The thermal analysis results, before and after failure, are displayed in line at the area of the LED elements and in 3D on the screen surface. The photometric analysis was done on the full-screen area in each of the RGB channels and then followed with in-detail measurements on 200 points. As most photons emitted from the diode are dispersed to the sides of the display due to the lens mounted on top of each LED and other optical elements, data obtained by photometric means are not as precise in the positioning of faulty LEDs, as ones obtained by thermal inspection.

The Dangers of Analyzing Thermographic Radiometric Data as Images

“…In a similar manner, the method is used in material science for testing components. Next, IRT is used to search high-voltage nets, electrical installations and small-scale electronics for potentially dangerous hotspots that could lead to catastrophic failures, as detailed in [8]. Moreover, power plants are monitored by means of the IRT for optimal production, and wide geographic areas are monitored with IR cameras from an aerial point of view to detect geological properties or environmental damages.…”