Display DC-DC Converter Control for Flicker-Free Low Power Mode
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Solution Overview
Problem
Existing DC-DC converters in display devices face challenges in maintaining display quality by preventing flicker while reducing power consumption, particularly in low power modes where skipped switching leads to increased ripple in panel power voltage and luminance fluctuations.
Innovation Solution
A DC-DC converter with a switching controller that adjusts the threshold current based on load, operating in low power mode (Pulse Skip Mode) when the load is less than the threshold current and normal mode (Discontinuous or Continuous Conduction Mode) when the load is greater, using a switching control signal with adjustable minimum on-time to manage panel power voltage ripple and flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the DC-DC converter operates in Pulse Skip Mode to reduce power consumption, then power consumption decreases, but ripple of panel power voltage increases and flicker is generated
Solution Approach 1:
The patent dynamically adjusts the minimum on-time of the switching control signal based on operating conditions. The switching controller modifies the minimum on-time parameter to prevent flicker while operating in PSM, allowing the system to adapt between power efficiency and display quality requirements rather than using a fixed timing parameter
Solution Approach 2:
The patent changes the minimum on-time parameter of the switching control signal to resolve the contradiction. By adjusting this timing parameter, the system maintains sufficient switching activity to prevent voltage ripple and flicker while still operating in pulse skip mode for reduced power consumption
2Reliability
If the threshold current is increased to prevent flicker, then display quality improves, but power consumption increases
Solution Approach 1:
The patent employs dynamic adjustment of the minimum on-time parameter that varies with load conditions and operating mode. This dynamic control allows the system to maintain display quality across different threshold current settings without being locked into a fixed high-current configuration that would increase power consumption
Solution Approach 2:
The switching controller uses feedback mechanisms to monitor operating conditions and adjust the minimum on-time accordingly. This feedback control enables the system to prevent flicker by adapting the switching timing to actual load conditions rather than relying solely on increased threshold current
3Reliability
If the DC-DC converter operates in normal mode to prevent flicker, then display quality improves, but power consumption increases
Solution Approach 1:
The patent implements dynamic switching between PSM and normal mode based on load conditions, with the minimum on-time parameter being adjusted in each mode. This dynamic operation allows the system to spend most time in efficient PSM while transitioning to normal mode only when necessary to maintain display quality
Solution Approach 2:
The system uses periodic evaluation of load conditions to determine when to switch between PSM and normal mode. The switching controller periodically assesses whether the current load warrants transition from power-saving mode to full-performance mode, optimizing the balance between power consumption and display quality
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 effectively prevents flicker and reduces power consumption by adjusting the threshold current and minimum on-time of the switching control signal, ensuring stable panel power voltage and improved display quality.
Implementation Method 1
an inductor connected to the first switching element and the second switching element
Data Source
AI summary
A DC-DC converter includes a first switching element, a second switching element connected to the first switching element, an inductor connected to the first switching element and the second switching element, and a switching controller configured to generate a switching control signal for turning on the first switching element or the second switching element in response to a switching control clock signal, to reset the switching control signal in response to a reset signal, and to operate in a low power mode or a normal mode according to a load, which is a panel current, based on a threshold current. The threshold current is adjusted based on the switching control signal.