Always-On Display Voltage Control for Luminance and Power
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Solution Overview
Problem
Conventional always-on display modes suffer from low luminance issues in bright environments, making displayed information difficult to recognize, and high power consumption, which is not optimized for varying ambient light conditions.
Innovation Solution
A display device that includes a DC-DC converter and a display panel driver, which adjust the power supply voltage to pixels based on ambient illuminance, switching between high and low voltage levels to maintain visibility and minimize power consumption, with the DC-DC converter enabled in bright conditions and disabled in low-light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the DC-DC converter supplies high voltage to pixels in always on display mode, then visibility in bright environments is improved, but power consumption increases
Solution Approach 1:
The system dynamically switches between two power supply modes based on ambient illuminance conditions. In bright environments, the DC-DC converter supplies high voltage to ensure visibility. In low-light environments, the display panel driver supplies low voltage to reduce power consumption. This dynamic adaptation resolves the contradiction by adjusting luminance according to actual viewing conditions.
Solution Approach 2:
The patent changes the voltage level parameter supplied to pixels based on illuminance conditions. By switching between high voltage (from DC-DC converter) and low voltage (from display panel driver), the system optimizes the balance between luminance and power consumption for different ambient light conditions.
2Use of energy by moving object
If the display panel driver supplies low voltage to pixels, then power consumption is reduced, but visibility in bright environments deteriorates
Solution Approach 1:
The system dynamically selects the appropriate power supply source based on ambient illuminance. The illuminance sensor detects environmental light conditions and triggers the controller to switch between low-voltage mode (display panel driver) for power savings and high-voltage mode (DC-DC converter) for visibility, resolving the contradiction adaptively.
Solution Approach 2:
The illuminance sensor acts as an intermediary that detects ambient light conditions and provides feedback to the controller. This intermediary mechanism enables the system to automatically determine when to prioritize power savings versus visibility, resolving the contradiction through environment-based decision making.
3Illumination intensity
If the DC-DC converter is always enabled in always on display mode, then luminance is maintained, but power consumption increases
Solution Approach 1:
The patent segments the power supply function into two separate paths: one through the DC-DC converter for high-voltage operation and another through the display panel driver for low-voltage operation. This segmentation allows selective activation based on illuminance conditions, maintaining luminance when needed while reducing power consumption during low-light periods.
Solution Approach 2:
The display panel driver is designed with multi-functionality, serving both as a control unit and as a power supply source in low-light conditions. This universal design eliminates the need for continuous DC-DC converter operation, reducing power consumption while maintaining display functionality across different lighting environments.
Data Source
AI summary
A display device including: a display panel including a plurality of pixels configured to be driven in a normal mode or an always on display mode; an illuminance sensor configured to detect illuminance of ambient light; a direct current (DC)-DC converter configured to supply a power supply voltage having a first voltage level to the pixels through a power supply line when the illuminance is greater than a predetermined reference value in the always on display mode; and a display panel driver configured to supply a power supply voltage having a second voltage level to the pixels through the power supply line when the illuminance is less than or equal to the predetermined reference value in the always on display mode.