PWM Pixel Circuit Charging Control for Lower Static Power
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Solution Overview
Problem
Existing display devices face challenges in reducing static power consumption, particularly in pixel driving circuits where analog circuits continuously consume power regardless of display mode or screen requirements.
Innovation Solution
A pixel driving circuit is designed with a video memory to store video data, sub-pixel driving units with capacitors for power supply, a charge control memory to manage capacitor charging, and a charge controller to control capacitor charging based on stored data, reducing the number of charging cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If analog circuits are used for pixel driving, then continuous current supply is maintained ensuring stable operation, but static power consumption increases
Solution Approach 1:
The patent implements periodic charging of the capacitor unit based on grayscale values stored in the charge control memory. Instead of continuous charging, the capacitor is charged only when needed according to the display content, creating periodic action that reduces static power consumption while maintaining stable operation when required.
Solution Approach 2:
The patent dynamically adjusts the charging behavior of the capacitor unit based on the grayscale value. When the grayscale value indicates no change is needed, charging is skipped. This dynamic adaptation allows the circuit to transition from continuous operation to selective operation, reducing power consumption while maintaining reliability when changes are necessary.
2Stability of the object's composition
If capacitor charging is performed frequently to maintain power supply, then driving stability is ensured, but power consumption increases
Solution Approach 1:
The patent uses feedback by comparing the current grayscale value with the previously displayed grayscale value stored in the charge control memory. Only when a change is detected does the system charge the capacitor unit. This feedback mechanism ensures driving stability by maintaining power supply when needed while avoiding unnecessary charging that would increase energy loss.
Solution Approach 2:
The patent performs preliminary action by storing the grayscale value in advance in the charge control memory before the actual display refresh. This allows the system to determine in advance whether capacitor charging is necessary, enabling proactive power management that maintains stability while minimizing energy consumption by charging only when the stored grayscale value differs from the current frame.
Data Source
AI summary
A pixel module comprises a scan driver to output first signals, a data driver to output second signals, and a plurality of pixel circuits for driving an LED with PWM signals. Each pixel circuit comprises a first memory configured to store image data to drive the light-emitting diode, a second memory configured to store charging control data indicating charging timings or a number of charging times of a capacitor, and a PWM pixel driver comprising the capacitor configured to be chargeable when a supply of a bias voltage is turned on based on the charging control data, a charge controller configured to output a charging control signal according to the charging control data, and a PWM control element configured to control a power supply to the light-emitting diode, wherein the second signals transmit the image data to the first memory and the charging control data to the second memory.