LED String Driver Serial-to-Parallel Converter
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Solution Overview
Problem
Existing driver devices for OLED/LED strings face inefficiencies due to low utilization of LEDs in multiplexing setups, where only a fraction of the time cycle is used for activation, leading to reduced optical output, especially in high-power applications where peak current is limited.
Innovation Solution
A device comprising a controllable shunting switch, switch controller, and level shifting means for each OLED/LED element, forming a serial-to-parallel converter, allowing individual control of OLED/LED elements in a string without additional losses, enabling efficient switching and high utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiplexing is used to control multiple LEDs, then device complexity is reduced, but LED utilization and optical output are lowered
Solution Approach 1:
The patent divides the LED string into segments where each LED has its own controllable shunting switch, allowing individual control without requiring complex multiplexing. This segmentation enables each LED to be independently addressed while maintaining simpler driver architecture.
Solution Approach 2:
The patent introduces dynamic control through the shunting switch that can be independently controlled for each LED, allowing the system to transition from static multiplexing to dynamic individual control. This enables full utilization of LEDs while maintaining driver simplicity through modular control units.
2Device complexity
If LEDs are connected in series to reduce driver complexity, then device complexity is reduced, but individual switching becomes complicated due to floating reference potential
Solution Approach 1:
The patent introduces level shifting means as an intermediary component between the series-connected LEDs and the control circuitry. This level shifting mechanism translates control signals into the appropriate voltage levels for each LED's floating reference potential, enabling simple series connection while maintaining ease of individual switching control.
3Adaptability or versatility
If scanning matrix is used to control multiple LEDs, then control capability is improved, but activation time for each LED is reduced
Solution Approach 1:
The patent implements preliminary action by using a shift register to prepare control signals in advance. The shift register stores and sequences the activation signals for multiple LEDs, allowing each LED to be activated for its full intended duration without the time constraints of scanning matrix. This preliminary signal preparation enables both comprehensive control and adequate activation time.
Data Source
AI summary
The present invention relates to a device for individually driving OLED/LED elements of an OLED/LED string, comprising for each OLED/LED element of the string: a controllable shunting switch (22, 42) coupled with the respective OLED/LED element (14, 15), switch controller means (30, 44) for controlling said shunting switch (22, 42) and having a control output port coupled to said switch (22, 42), a data input port and a clock input port, level shifting means (32) assigned to said switch controller means (30, 44) and adapted to bring the control input data to a level sufficient to be accepted by the switch controller means (30, 44) during a programming mode and to allow the control of said shunting switch (22, 42). Said switch controller means (30, 44) of said OLED/LED elements (14, 15) are provided to form a serial-to-parallel converter means (31).