Panasonic Patents Show Work Underway to Boost OLED TV Picture Quality

Panasonic at IFA said it will use “decades" of knowledge in plasma TV picture quality to bring enhancements to the OLED TV panels it sources from LG Display. Demos of a prototype 4K OLED screen at IFA impressed, but Panasonic would give no information on what new tricks it plans for OLED, saying only it will release more information on the subject by winter. Our search through Panasonic patents filed over the past decade unearthed work underway at the company to enhance OLED’s picture quality. Two patents from parent Matsushita (US 2009/0046087 and 2009/0212715) describe how to dim OLEDs, smoothly and without flicker, by driving them with a pulsed voltage, and varying the shape and frequency of the pulse train. A third U.S. filing (2009/0153449) describes advances in OLED screen technology, and related Japanese patents (JP 12359455 and JP 20120014182) name Hitachi and Panasonic as joint applicants. When combined, these patents explain how using thin-film transistors (TFTs) to switch OLED pixels improves light output and makes the screen look brighter. But an unwanted side effect is that TFTs can blur motion because residual picture signals linger in the TFT capacitors so that one picture scan smears into the next, the patents said. Panasonic’s patented solution is to completely quench all the pixels between every scanning line, rather like physically switching off a light, the patents said. The extreme quenching is done by rapidly reversing the voltage after each line scan, they said. The result, they said, is prevention of the blurred edge “phenomenon,” which “greatly improves” motion clarity.