Design Of The Driving Scheme Of 7 Inch LTPS AM-OLED

Polycrystalline silicon has the advantage of high carrier mobility, and it is used as the material of TFT of AM-OLED (Active Matrix Organic Light Emitting Display). However, its non-uniformity of characteristic may cause non-uniformed brightness, which finally results in imprecise gray scale of the panel. Conventional driving schemes can't solve the problem. So it's very meaningful to make a driving scheme that can solve this problem.In this paper, a driving scheme of 7 inch 16,000,000 color AM-OLED is contrived, the design is made as the follows: First, a 3-TFT AM-OLED pixel circuit is designed. The parameters are confirmed by related rules and simulation is carried out by Hspice. Results show the ability of compensating for shift of TFT threshold-voltage, as well as good linearity. Layout is drawn and aperture ratio is calculated. Error-rate is also discussed. This pixel circuit has the advantage of high aperture ratio and easy driving timing. Then, as large scale AM-OLED driver IC is still unavailable today, a PM-OLED driver IC, CLARE MXED101 is chosen to drive 7 inch AM-OLED. It provides current output, and can achieve 64-level gray scale. The video interface circuit is designed and HDMI interface is chosen. Pictures are transmitted by digital signals to avoid losing image details. At last, a combined scheme is used to increase the gray scale level at 4 times and 16,000,000 colors are obtained. The combined scheme is used in the 5 inch 4bit (16-level gray scale) AM-OLED driving system, and 61-level gray scale is successfully obtained, which testifies our method.A feasible scheme for the National 863 plans projects, 7 inch AM-OLED driving technology, is provided.