DC-DC Converter for OLED Displays with Dynamic Voltage Regulation
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Solution Overview
Problem
Conventional DC-DC converters for organic light emitting displays are limited in their ability to generate a stable first power supply voltage (ELVDD) when using high-capacity batteries, as they struggle to manage input voltages above a certain threshold, restricting the use of batteries with higher voltage outputs.
Innovation Solution
A DC-DC converter that includes a booster circuit and an inverter circuit, controlled by a PWM controller, which adjusts its operation to generate a consistent first power supply voltage (ELVDD) of 4.6V regardless of the input voltage from the battery, by boosting or reducing the voltage as necessary, and inverts the supply to generate a second voltage (ELVSS) suitable for the organic light emitting diodes, ensuring efficient operation across varying battery voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a high-capacity battery with larger voltage output is used to extend use time, then the duration of action is improved, but the conventional booster circuit cannot generate stable voltage when input voltage exceeds a certain threshold
Solution Approach 1:
The patent implements a dynamic voltage regulation system that automatically adjusts its operation mode based on the input voltage level. When input voltage is below 4.2V, the booster circuit operates in boosting mode; when input voltage exceeds 4.2V, the system switches to voltage reduction mode using a switching circuit and reference voltage comparison mechanism. This dynamic adaptation allows the system to maintain stable 4.6V output regardless of battery capacity or voltage variations, resolving the contradiction between extended use time and voltage stability.
Solution Approach 2:
The patent changes the operational parameters of the voltage regulation system based on input conditions. By monitoring input voltage levels and adjusting the switching state of transistors (T1, T2, T3, T4) and the configuration of inductors (L1, L2) and capacitors (C1, C2), the system adapts its voltage transformation characteristics. This parameter adjustment enables the system to handle both low-voltage (boosting) and high-voltage (reduction) scenarios, maintaining reliable output voltage while supporting high-capacity batteries for extended operation.
2Duration of action of moving object
If the battery capacity is increased to extend use time, then the duration of action is improved, but the input voltage may exceed the booster circuit's operating range
Solution Approach 1:
The patent creates a universal voltage regulation system that can handle multiple input voltage scenarios through a single integrated circuit design. The system incorporates both boosting functionality (for low-voltage batteries) and voltage reduction capability (for high-voltage batteries) within the same hardware architecture. By using a combination of inductors, capacitors, diodes, and controllable switching elements that can operate in different configurations, the system achieves multi-functionality, adapting to various battery capacities and voltage outputs without requiring separate circuits for each scenario.
Solution Approach 2:
The system dynamically reconfigures its internal circuit topology based on input voltage levels. When input voltage is low, the circuit operates as a traditional boost converter; when input voltage exceeds the threshold, the switching circuit redirects current flow through alternative paths using the same physical components. This dynamic reconfiguration expands the adaptability of the system, allowing it to work with batteries of various capacities and voltage ratings, thereby supporting extended use time without being constrained by input voltage range limitations.
3Device complexity
If a conventional booster circuit is used, then the circuit complexity is kept simple, but the boosting range of voltage is limited
Solution Approach 1:
The patent segments the voltage regulation function into distinct operational stages handled by different circuit blocks. The system divides the voltage transformation task between a boosting stage (using inductor L1, capacitor C1, and switching elements) and a voltage reduction stage (using inductor L2, capacitor C2, and reference voltage comparison). This segmentation allows each stage to be optimized for its specific function while maintaining overall system simplicity. The modular structure enables the circuit to handle a broader voltage range without significantly increasing overall complexity, as each segment remains relatively simple but works in coordination with the other.
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 allows for the extended use time of organic light emitting displays by enabling the use of high-capacity batteries, ensuring consistent image display even under conditions where the battery voltage exceeds the conventional booster circuit's limitations.
Implementation Method 1
a first inductor L1 having one terminal coupled to the capacitor C and the other terminal coupled to a first node N1
Implementation Method 2
organic light emitting diodes (OLEDs) that generate light by the recombination of electrons and holes generated corresponding to the flow of current
Data Source
Figure 1~2
Figure 3~4
AI summary
A DC-DC converter generates a first power and a second power for driving pixels in an organic light emitting display, such that the voltages of the first power and the second power are substantially independent of the voltage from a power supply or a battery. A voltage detector detects the voltage from the power supply, and a booster circuit and an inverter circuit respectively boost and invert the voltage from the power supply to generate and output the first and the second powers, respectively, for the pixels. A PWM controller controls the booster circuit and the inverter circuit to control voltages of the first power and the second power. The booster circuit is adapted to reduce the voltage from the power supply to be lower than the voltage of the first power when the voltage from the power supply detected by the voltage detector is higher than a reference voltage.