Scan Driver Multi-Frequency Driving for Partial Region Power Reduction
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Solution Overview
Problem
In display devices, especially in portable devices like smartphones and tablets, reducing power consumption is crucial, but existing low frequency driving techniques fail to minimize power usage when displaying still images on partial regions of the display panel, as the entire panel is often driven at normal frequency, leading to inefficiency.
Innovation Solution
A scan driver capable of multi-frequency driving (MFD) is introduced, which includes first and second stages that output intermediate and scan signals respectively, with masking transistors controlling the output based on a masking signal, allowing different driving frequencies for various panel regions, thereby optimizing power usage by selectively applying scan signals during hold periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low frequency driving technique is applied to reduce power consumption, then power consumption is reduced, but the entire display panel must be driven at normal frequency when still images are displayed only in partial regions, preventing power savings
Solution Approach 1:
The display panel is divided into multiple regions (first region and second region) that can be driven at different frequencies. The scan driver generates scan signals at different frequencies for different regions, allowing the first region to operate at normal frequency while the second region operates at low frequency when displaying still images, thus reducing overall power consumption while maintaining adaptability to various display content types
Solution Approach 2:
Different regions of the display panel are assigned different driving frequencies based on their content requirements. The first region displays moving images at normal frequency while the second region displays still images at low frequency. This local differentiation allows each region to operate optimally for its specific content, reducing overall power consumption while maintaining display quality where needed
2Reliability
If the entire display panel is driven at normal frequency, then display quality is maintained, but power consumption cannot be reduced even when only partial regions display still images
Solution Approach 1:
The display panel is segmented into multiple regions with independent frequency control. The scan driver generates scan signals at different frequencies for different regions, allowing the first region to operate at normal frequency while the second region operates at low frequency when displaying still images, thus reducing overall power consumption while maintaining adaptability to various display content types
Solution Approach 2:
The driving frequency of each region is dynamically adjusted based on the displayed content. When still images are displayed in the second region, the frequency is reduced to save power. When moving images are displayed, the frequency returns to normal to maintain display quality. This dynamic adjustment allows the system to optimize between power consumption and display quality in real-time
Data Source
AI summary
A scan driver includes: a plurality of first stages configured to sequentially output a plurality of intermediate scan signals based on a scan start signal; a plurality of masking transistors respectively connected to a plurality of output terminals of the plurality of first stages, and configured to selectively transfer the plurality of intermediate scan signals in response to a masking signal, respectively; and a plurality of second stages including a plurality of input terminals respectively connected to the plurality of masking transistors, and configured to selectively output a plurality of scan signals based on the plurality of intermediate scan signals selectively transferred by the plurality of masking transistors.