AMLCD and AMOLED for Low Power LCD Consumption Factors
09.25.2023
With the increase in display resolution and display area of mobile terminals, the power consumption of displays has become an important part of the overall system power consumption.
AMLCD is a voltage-driven display that can utilize existing a-Si, LTPS and Oxide TFT to achieve coverage from small to large display sizes; and with the conversion of liquid crystal materials, Mini-LED backlight, Dual-cell, QD fluorescence with the development of materials and technologies such as thin film, display quality will continue to improve and power consumption will be further reduced. AMLCD has formed a mature scale manufacturing process and industry chain system, and has certain advantages in product applications.
AMOLED is a current-driven display, which requires complex pixel driving circuits and high requirements for TFT performance. At present, small size AMOLED displays mainly use LTPS TFT, while large size AMOLED displays use oxide TFT. Compared with AMLCD, AMOLED has the advantage of ultra-thin, flexible, and even foldable and curlable, representing the trend of display technology to all-solid-state semiconductor display, which can display a very ideal is black state, is the form of mobile terminal products. The innovation of integration with the function provides a broader space. However, there are still shortcomings such as aging and poor display effect. With the improvement of its mass production technology, AMOLED display will be increasingly used in smart phones, wearable electronics and other mobile terminal products.
The power consumption of the display is mainly divided into two parts: static power consumption and dynamic power consumption. For AMLCD and AMOLED, the dynamic power consumption is mainly the power consumption consumed by the signal written to each pixel during the display refresh process.
The static power consumption of AMLCD mainly comes from the backlight, while the static power consumption of AMOLED comes from the current path formed by driving the TFT and OLED.
As the display resolution increases, dynamic power consumption gradually becomes an important component. In order to reduce dynamic power consumption, the parasitic capacitance in the display pixel array can be reduced, the operating voltage can be lowered, and the refresh frequency can be reduced according to the display content.
To reduce static power consumption, for AMLCD, the efficiency of the backlight and the light utilization efficiency of the whole optical system can be improved, and the use of Mini-LED backlight can be fine-grained dimming according to the display content, which can also effectively reduce static power consumption.
For AMOLED, it is necessary to further improve the efficiency of OLED (including light extraction efficiency) through the design of high-performance materials and devices to reduce the cross-pressure of driving TFTs. However, as the OLED efficiency increases and the pixel size decreases, the required pixel current decreases significantly.
As a result, the driving TFT will operate in the deep sub-threshold region at low grayscale, leading to poor display, difficult grayscale accuracy, regulation and control issues and challenges.