OLED Charge Pump Phase Segmentation for Efficiency
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Solution Overview
Problem
Conventional OLED display panel charge pumps experience reduced charge transferring efficiency when the absolute value of the output voltage is close to the operating voltage, often as low as 50%, which needs to be improved.
Innovation Solution
A charge pump design for OLED display panels incorporating multiple switches and capacitors, operated in specific phases to generate negative output voltages, with a control circuit to regulate the switching and optimize efficiency, allowing selection of optimal switching modes for -1 to -2 times negative output voltage generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional charge pump is used to generate negative output voltage, then the device can provide negative voltage, but the charge transferring efficiency deteriorates when the absolute value of output voltage is close to the operating voltage
Solution Approach 1:
The charge pump is divided into multiple operational phases (first phase, second-A phase, second-B phase) with different switching configurations. Each phase is optimized for specific output voltage ranges, allowing the system to segment the voltage generation task to maintain high efficiency across different operating conditions.
Solution Approach 2:
The charge pump employs dynamic switching control where different sets of switches are activated based on the desired output voltage level. The control circuit dynamically selects between first switching control signal and second switching control signal to optimize charge transferring efficiency for different negative output voltage magnitudes.
2Productivity
If the charge pump operates in conventional switching modes, then the circuit structure remains simple, but the charge transferring efficiency drops to as low as 50% when output voltage approaches operating voltage
Solution Approach 1:
The control circuit monitors the output voltage level and adjusts the switching control signals accordingly. By providing feedback on the operating conditions, the control circuit selects the appropriate switching mode (first or second switching control signal) to maintain optimal charge transferring efficiency across different output voltage ranges.
Solution Approach 2:
The system changes switching parameters (which switches are closed and for how long) based on the desired output voltage level. By adjusting the switching configuration and timing, the charge pump optimizes charge transferring efficiency without requiring fundamental changes to the hardware architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The charge pump significantly improves charge transferring efficiency, achieving up to 70% efficiency even when the output voltage is close to the operating voltage, compared to the conventional 50% efficiency.
Implementation Method 1
The plurality of capacitors includes a first capacitor, a second capacitor and a third capacitor... The first switch and the second switch are coupled in series between a first voltage and a second voltage... the first capacitor is charged by the first voltage
Data Source
AI summary
A charge pump, applied to an OLED display panel and coupled to an output capacitor, includes a first switch to a tenth switch and a first capacitor to a third capacitor. The first switch and second switch are coupled in series between a first voltage and a second voltage lower than first voltage. The third switch is coupled to second voltage. The sixth switch is coupled to first voltage. The seventh switch is coupled to second voltage. The fourth switch, eighth switch and tenth switch are coupled to output capacitor. The first capacitor is coupled between first switch and second switch. The second capacitor is coupled between fifth switch and sixth switch. The third capacitor is coupled between seventh switch and eighth switch. The charge pump is operated in a first phase, a second-A phase, the first phase and a second-B phase in order to provide negative output voltage.