Display Power Supply Circuit Frequency Control for Efficiency
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Solution Overview
Problem
Existing power supply circuits for liquid crystal panels face inefficiencies due to varying current consumption, leading to degraded power efficiency during high-load and low-load periods, as they either prolong charging periods or excessively charge coils, resulting in voltage drops and reduced efficiency.
Innovation Solution
A power supply circuit that includes a frequency control circuit to dynamically adjust the frequency of a clock signal based on vertical and horizontal synchronizing signals, switching between different frequency states during high-load and low-load periods, and controlling the charging and discharging of a coil with a MOS switch to stabilize output voltage and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the duty ratio is set to be the same for high-load and low-load periods, then the control is simple, but the output voltage drops greatly causing power efficiency degradation
Solution Approach 1:
The patent applies dynamics by making the duty ratio adjustable based on load conditions. The control circuit dynamically changes the duty ratio between first and second values depending on whether the system is in high-load or low-load period, allowing optimal power efficiency for each condition while maintaining manageable control through automatic detection of load states.
Solution Approach 2:
The patent changes the duty ratio parameter according to load conditions. By switching between different duty ratio values (first duty ratio for high-load, second duty ratio for low-load), the system adapts to varying power requirements and maintains high power efficiency without excessive complexity.
2Stability of the object's composition
If the ON/OFF frequency is increased to suppress voltage drop in high-load period, then voltage stability improves, but the coil charging becomes excessive in low-load period increasing output voltage and degrading power efficiency
Solution Approach 1:
The patent makes the switching frequency dynamic by adjusting it according to load conditions. The control circuit increases frequency during high-load periods to maintain voltage stability, and decreases it during low-load periods to prevent excessive charging and maintain power efficiency.
Solution Approach 2:
The patent uses periodic switching at variable frequencies to control the power supply. By adjusting the switching period based on load demands, the system achieves both voltage stability during high-load and power efficiency during low-load periods.
3Stability of the object's composition
If the charging period of the coil is prolonged to generate desired output voltage at high load, then the output voltage is maintained, but the electromotive force of the coil increases and power efficiency is degraded
Solution Approach 1:
The patent dynamically adjusts the charging period duration based on load conditions. During high-load periods, the charging period is extended to maintain output voltage, while during low-load periods it is shortened to reduce electromotive force and improve power efficiency.
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
This solution effectively prevents voltage drops during high-load periods and maintains power efficiency by shortening charging times and optimizing the frequency of the clock signal, thereby enhancing overall power supply efficiency.
Implementation Method 1
A power supply circuit using a switching regulator charges a coil with charges corresponding to an input voltage and discharges the charged charges from the coil, thereby boosting a voltage.
Data Source
AI summary
Provided are a power supply circuit and a display device which are capable of enhancing power efficiency even when applied to a display panel whose current consumption varies. The power supply circuit boosts and outputs an input voltage using a booster chopper circuit. A frequency control circuit changes a frequency of a clock signal, which controls a switch of the chopper circuit, in accordance with a load of the power supply circuit. The frequency control circuit divides an operation of the display device into a display effective period at a high load and a vertical retrace period at a low load, based on a vertical synchronizing signal and a horizontal synchronizing signal. The frequency control circuit sets the frequency of the clock signal in a high-load period to be higher than that in a low-load period.