Display Driver Still Image Detection Frequency Adaptation
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Solution Overview
Problem
Display devices in portable devices, such as smartphones and tablets, face challenges in reducing power consumption when decoding compressed image bitstreams, as they often operate at input frame frequencies that do not align with the lower driving frequencies used to reduce power consumption.
Innovation Solution
A display device with a still image detector and a variable frequency decoder that compares compressed image bitstreams between frames to determine if a still image is present, adjusting the output frame frequency to either match the input frame frequency for moving images or reduce it for still images, thereby optimizing power usage by decoding at a lower frequency when still images are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the display panel is driven at a frequency lower than the input frame frequency to reduce power consumption, then power consumption is reduced, but the compressed image bitstream must be decoded at the higher input frame frequency which consumes additional power
Solution Approach 1:
The decoder dynamically adjusts its operating frequency based on the detected image type. For still images, the decoder operates at the lower display driving frequency, while for moving images, it operates at the higher input frame frequency. This dynamic adaptation eliminates the mismatch between display frequency and decoding frequency, reducing unnecessary power consumption in the decoding process.
Solution Approach 2:
The system changes the operating parameter (decoding frequency) of the decoder based on the detected image characteristics. By detecting whether the input image is a still image or moving image, the system adjusts the decoder's working frequency to match the actual requirements, thereby optimizing power consumption while maintaining image quality.
2Reliability
If the decoder operates at the input frame frequency to decode compressed image bitstreams, then image quality is maintained, but power consumption increases
Solution Approach 1:
The decoder's operating frequency parameter is dynamically adjusted based on image type detection. For still images, the decoder operates at the lower display driving frequency, which is sufficient to maintain image quality since no temporal changes need to be captured. For moving images, the decoder operates at the higher input frame frequency to preserve motion details. This selective parameter adjustment maintains image quality while reducing power consumption for still images.
Solution Approach 2:
The system transitions from a static decoding frequency (always at input frame frequency) to a dynamic decoding frequency that adapts to the content being displayed. This dynamic adjustment allows the system to use the minimum necessary decoding frequency for each frame type, optimizing the balance between image quality and power consumption.
Data Source
AI summary
A display driver includes a still image detector configured to receive a compressed image bitstream at an input frame frequency from a host processor, and to detect a still image by comparing the compressed image bitstream of a current frame and the compressed image bitstream of a previous frame, a driving frequency changer configured to output the compressed image bitstream at a first output frame frequency equal to the input frame frequency when the still image is not detected, and to output the compressed image bitstream at a second output frame frequency lower than the input frame frequency when the still image is detected, and a decoder configured to generate original image data at the first output frame frequency and the second output frame frequency.