Display Panel Frequency Control for Power Savings
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Solution Overview
Problem
Display devices consume excessive power, particularly when displaying still images, due to continuous operation of the graphic processing unit, and existing power-saving methods like Panel Self Refresh (PSR) mode increase power consumption with the addition of frame memory.
Innovation Solution
A display device and driving method that alternates between two frequencies, with a higher frequency for motion pictures and a lower frequency for still images, reducing power consumption and preventing flicker by using a frame memory to store image data and controlling clock signals and vertical blank periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Panel Self Refresh (PSR) mode is used to store image data in frame memory, then power consumption is reduced by deactivating the graphic processing unit, but the addition of frame memory increases power consumption
Solution Approach 1:
The patent dynamically adjusts the driving frequency of the display panel based on content type: using a first (lower) frequency for still images to save power, and a second (higher) frequency for motion pictures to maintain image quality. This dynamic frequency adjustment resolves the contradiction by optimizing power consumption without requiring additional frame memory hardware.
Solution Approach 2:
The patent changes the operating parameter (driving frequency) of the display panel according to the displayed content. By switching between two frequency modes, the system achieves power savings for still images while maintaining performance for motion pictures, eliminating the need for PSR mode and its associated frame memory overhead.
2Use of energy by moving object
If the display panel is driven at a lower frequency to reduce power consumption, then energy savings are achieved, but flicker and afterimage issues occur
Solution Approach 1:
The system dynamically switches between two driving frequencies based on content type. For still images, it uses the first frequency with extended vertical blank periods to reduce power consumption. For motion pictures, it switches to the second frequency to prevent flicker and afterimage effects. This dynamic adaptation resolves the contradiction between power savings and visual quality.
Solution Approach 2:
The patent implements periodic action by alternating between two frequency modes and adjusting vertical blank periods. The extended vertical blank periods at lower frequency provide sufficient time for liquid crystal relaxation, preventing afterimage effects while maintaining power savings. This periodic structure allows the system to achieve both low power consumption and flicker-free display.
3Use of energy by moving object
If the display panel is driven at alternating frequencies for still images, then power consumption is reduced and flicker is minimized, but liquid crystal deterioration may occur due to extended vertical blank periods
Solution Approach 1:
The patent applies preliminary anti-action by introducing dummy data enable signals during the extended vertical blank periods. These dummy signals prevent liquid crystal molecules from remaining in a stressed state too long, counteracting the potential deterioration caused by extended blank periods at lower frequencies. This allows the system to maintain both power savings and liquid crystal reliability.
Solution Approach 2:
The dummy data enable signals act as an intermediary mechanism during the vertical blank periods. They mediate between the power-saving low-frequency operation and the protection of liquid crystal durability by ensuring proper signal timing and preventing excessive stress accumulation in the liquid crystal material.
Data Source
AI summary
The present invention relates to a display device capable of reducing power consumption and preventing flicker, as well as a driving method thereof. An exemplary display device includes: a display panel configured for display of a still image and a motion picture; a signal controller programmed to transmit control signals for driving the display panel; and a graphic processing unit transmitting input image data to the signal controller. The signal controller includes a frame memory storing the input image data, and the display panel is driven at a first frequency when the motion picture is displayed and alternatingly driven at the first frequency and a second frequency when the still image is displayed, the second frequency being lower than the first frequency.