DC-DC Converter Voltage Transition Control for Display Stability
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Solution Overview
Problem
Display quality deteriorates due to power voltage drops during switching processes between operation modes in DC-DC converters, leading to issues like screen blinking in display devices.
Innovation Solution
A DC-DC converter design that includes an inductor and transistors to precharge and output power voltage using specific driving schemes, changing voltage levels over different periods based on mode transitions to prevent inrush current and voltage drops, with a switching controller managing transistor operations and impedance adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the DC-DC converter switches between operation modes to reduce power consumption, then power consumption is reduced, but power voltage drops occur causing display quality deterioration
Solution Approach 1:
The patent applies preliminary action by pre-charging the output capacitor before switching from low power mode to normal mode. The controller activates a pre-charge transistor that connects the input voltage directly to the output capacitor through a pre-charge path, charging the capacitor in advance. This preliminary charging action ensures that when the main switching occurs, there is no sudden voltage drop that would cause display quality deterioration, thus resolving the contradiction between power consumption reduction and display quality maintenance.
2Speed
If the voltage level changes rapidly to reach reference output voltage, then response speed is improved, but inrush current increases causing voltage drops
Solution Approach 1:
The patent uses an intermediary approach by introducing a pre-charge transistor and pre-charge path as intermediate elements between the input voltage source and the output capacitor. This intermediary pre-charge path allows controlled charging of the output capacitor before the main power switch closes, preventing direct inrush current while still achieving rapid voltage response. The intermediary mechanism resolves the contradiction by providing a controlled transition path that avoids harmful inrush current effects.
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
Prevents display quality deterioration by managing power voltage transitions, reducing inrush current and voltage drops, and maintaining stable power supply during mode changes, thus enhancing display performance.
Implementation Method 1
a first inductor current is generated by alternately turning on the transistors
Implementation Method 2
one of the first high voltage and the first low voltage has a turn-on voltage level configured to turn a transistor on when applied to a gate of the transistor
Data Source
AI summary
A display device includes a display panel which displays an image in a normal mode or low power mode. A DC-DC converter supplies a source driving voltage to the data driver, and supplies a first power voltage to the power line of the display panel in the normal mode. The data driver supplies a first auxiliary power voltage to the power line of the display panel in the low power mode. The DC-DC converter gradually changes the voltage level of the first power voltage to a reference output voltage level over a first period when the display panel initially enters into the normal mode, and changes the voltage level of the first power voltage to the reference output voltage level over a second period shorter than the first period when the mode of the display panel is switched from the low power mode to the normal mode.