Display Driver Power Gating for Monochromatic Display Modes
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Solution Overview
Problem
Portable information terminals, such as smartphones, face challenges in reducing power consumption due to increased demands from high-definition, high-gradation, and high-speed display requirements, particularly in display drivers that drive liquid crystal or organic EL display panels.
Innovation Solution
A display driver system that includes gradation reference voltage generating circuits, DA conversion circuits, amplifiers, and a switch circuit, which selectively operates based on display mode signals to minimize power consumption by stopping unnecessary components during monochromatic displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-definition, high-gradation, and high-speed display requirements are implemented, then image quality is improved, but power consumption increases
Solution Approach 1:
The display driver dynamically adjusts its operation mode based on the display content. When monochromatic display is detected, the system transitions to a power-saving mode where amplifiers and gradation reference voltage generating circuits are stopped, while maintaining basic display functionality through the switch circuit and remaining DA conversion circuits
Solution Approach 2:
Instead of fully operating all amplifiers and gradation reference voltage generating circuits for every display mode, the system applies partial action by selectively operating only the necessary components for monochromatic display, thereby reducing overall power consumption while maintaining adequate image quality for the specific display mode
2Reliability
If all amplifiers and gradation reference voltage generating circuits operate continuously, then normal display quality is maintained, but power consumption cannot be reduced
Solution Approach 1:
The display driver is segmented into functionally independent components (amplifiers, gradation reference voltage generating circuits, switch circuit, DA conversion circuits). This segmentation allows the system to selectively operate only the necessary segments for monochromatic display, reducing power consumption while maintaining display quality through proper control of each segment's operation
Solution Approach 2:
The system changes operational parameters by switching between different display modes (normal display vs. monochromatic display). This parameter change enables the system to adjust the operational state of amplifiers and gradation reference voltage generating circuits, stopping them during monochromatic display to reduce power consumption while maintaining quality through optimized control
Data Source
AI summary
A display driver includes a plurality of DA conversion circuits, amplifiers, and a switch circuit. Each of the DA conversion circuits outputs a gradation reference voltage in a gradation reference voltage group generated by one of gradation reference voltage generating circuits as a gradation voltage. The amplifiers each output a voltage output a voltage obtained by amplifying each gradation voltage as an output voltage. The switch circuit receives an output voltage group output from the amplifiers and a gradation voltage group generated by the respective DA conversion circuits coupled to a specific gradation reference voltage generating circuit. The switch circuit outputs the output voltage group to the display panel when a normal display mode while outputting the gradation voltage group to the display panel when a monochromatic display mode. At this time, when the monochromatic display mode, operation of the amplifiers and each gradation reference voltage generating circuit excluding the specific gradation reference voltage generating circuit is stopped.