OLED display field analysis

Organic light-emitting diode (OLED) displays are becoming more and more popular, and are most prominent in products such as cell phones, media players, and small entry-level TVs. Unlike standard liquid crystal displays, OLED pixels are driven by a current source. To understand how and why OLED power supplies affect display quality, you must first understand OLED display technology and power supply requirements. This article will explain the latest OLED display technologies and explore key power supply requirements and solutions, as well as an innovative power supply architecture for OLED power supply needs. Backplane technology for flexible displays High-resolution color active matrix organic light-emitting diode (AMOLED) displays require an active matrix backplane that uses active switches for switching individual pixels. At present, the liquid crystal (LC) display amorphous silicon process has matured, and it can supply a low-cost active matrix backplane and can be used for OLED . Many companies are currently developing organic thin-film transistor (OTFT) backplane processes for flexible displays, which can also be used in OLED displays to enable the introduction of full-color flexible displays. Both standard and soft OLEDs require the same power supply and drive technology. To understand the OLED technology, its capabilities, and its interaction with the power supply, you must delve into the technology itself. The OLED display is a self-illuminating display technology that does not require any backlight at all. The material used in OLED is an organic material suitable for chemical structure. OLED technology requires a current-controlled driving method. OLEDs have electrical characteristics that are quite similar to standard light-emitting diodes (LEDs) , and the brightness is dependent on the LED current. To turn the OLED on and off and control the OLED current, a thin film transistor (TFT) control circuit is required. The advanced energy-saving mode achieves the highest efficiency and is the same as any battery-powered device. Only when the converter operates at the highest efficiency of the overall load current range can a long battery standby time be achieved, which is especially important for OLED displays. The OLED display consumes the most power when it is completely white, and the current is relatively small for any other display color, because only white requires all red, green, and blue sub-pixels to be fully lit. For example, a 2.7 -inch display requires 80 mA of current to render an all-white image, but only 5 mA is needed to display other icons or graphics. Therefore, OLED power supplies need to achieve high converter efficiency for all load currents. In order to achieve such efficiency, advanced energy-saving mode technology is needed to reduce the load current to reduce the converter switching frequency. Since this is done through a voltage controlled oscillator (VCO) , it is possible to minimize possible EMI problems and to control the lowest switching frequency outside the normal 40 kHz audio range, which avoids noise from ceramic input or output capacitors. . This is especially important when using such devices in mobile applications, and it simplifies the design process.