Display Boost Circuit Control to Prevent Skip-Cycle Screen Noise
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Solution Overview
Problem
The boost circuit in electronic devices experiences unstable operation and noise on the display screen when the input voltage is similar to or higher than the output voltage, leading to a 'skip cycle' phenomenon, which causes irregular voltage changes and power loss when additional circuits are connected to maintain output stability.
Innovation Solution
A boost circuit with a first and second switching device, an inductor, an output capacitor, and a control circuit that stabilizes the overdrive voltage by blocking leakage current based on a system voltage threshold, preventing the 'skip cycle' and minimizing power loss without additional load circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the input voltage of the boost circuit is increased during battery charging, then the charging speed is improved, but the boost circuit cannot stably control the output voltage when the input voltage reaches or exceeds the driving voltage level
Solution Approach 1:
The patent applies dynamics by making the boost circuit operable in both boost mode and buck mode depending on the input voltage level. When input voltage is below the driving voltage, the circuit operates in boost mode; when input voltage reaches or exceeds the driving voltage, it switches to buck mode. This dynamic mode switching allows the circuit to maintain stable output voltage control while accommodating high input voltage during fast charging.
2Reliability
If the operation of the boost converter is periodically stopped to handle high input voltage, then the output voltage control is maintained, but a skip cycle phenomenon occurs causing irregular voltage changes and screen noise
Solution Approach 1:
The patent applies periodic action through controlled duty cycle modulation of the switching devices. Instead of periodically stopping the boost converter operation which causes skip cycle phenomenon, the circuit uses regulated periodic switching with adjusted duty cycles to maintain continuous operation. This ensures smooth voltage output without irregular interruptions that would cause screen noise.
3Reliability
If an additional boost circuit is connected to the boost converter to maintain constant output voltage when input voltage is high, then the output voltage stability is improved, but power loss increases in the load circuit
Solution Approach 1:
The patent applies parameter changes by transitioning the circuit operation from boost mode to buck mode based on input voltage parameters. When input voltage is below the driving voltage, the circuit uses boost operation; when input voltage reaches or exceeds the driving voltage, it switches to buck operation. This parameter-based mode switching eliminates the need for additional boost circuits and reduces power loss while maintaining output voltage stability.
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 solution maintains stable output voltage and reduces screen noise by controlling the boost circuit operation, even when the input voltage is higher than the output voltage, minimizing additional power loss.
Implementation Method 1
an inductor between an input terminal of the boost circuit and the first node
Implementation Method 2
an output capacitor configured to generate a direct current (DC) overdrive voltage by smoothing an alternating current (AC) current generated by the first switching device and the second switching device
Data Source
AI summary
An electronic device includes: a display; a battery; and a boost circuit to receive power from the battery and to supply a driving voltage to the display. The boost circuit includes: a first switching device connected to a first node; a second switching device connected to the first node; an inductor between an input terminal of the boost circuit and the first node; an output capacitor to generate a DC overdrive voltage by smoothing an AC current generated by the first switching device and the second switching device; a blocking device to block a leakage current of the battery; and a control circuit to control the overdrive voltage by controlling the blocking device, based on a system voltage that is equal to or greater than a threshold voltage, and wherein the system voltage is an input voltage of the boost circuit.