LED Driver PWM Current Segmentation for Finer Gray Scale
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Solution Overview
Problem
Conventional LED display devices have limitations in adjusting brightness levels, leading to poor gray scale expression and limited enlargement capabilities due to restricted pulse width modulation (PWM) control and clock frequency constraints.
Innovation Solution
The implementation of a light emitting diode (LED) driving device with multiple driving current sources connected in parallel, a PWM controlling circuit, and switch circuits to generate PWM signals that adjust the ON section length in units of clock cycles, allowing for finer gray scale control and reduced electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PWM control is used with a single driving current source, then the device complexity is low, but the gray scale expression precision is poor
Solution Approach 1:
The patent divides a single driving current source into multiple parallel current sources (first, second, third, and fourth driving current sources). Each current source is controlled by a separate PWM signal, allowing independent adjustment of duty cycles. This segmentation enables finer gray scale control by combining different current levels, resolving the contradiction between precision and complexity.
Solution Approach 2:
The patent implements dynamic control by adjusting the duty cycles of multiple PWM signals independently. The controller can dynamically allocate current from different sources based on required gray scale levels, enabling adaptive brightness control. This dynamic approach allows precise gray scale expression without requiring a fixed complex circuit structure.
2Measurement precision
If the clock frequency is increased to improve gray scale adjustment resolution, then the gray scale control precision is improved, but the electromagnetic interference increases
Solution Approach 1:
Instead of using a single high-frequency clock, the patent segments the driving current into multiple sources that can be controlled at lower frequencies. By distributing the control across multiple current sources with independently adjustable duty cycles, the system achieves fine gray scale resolution without requiring high clock frequencies, thereby reducing electromagnetic interference.
Solution Approach 2:
The patent changes the control parameter from clock frequency to PWM duty cycle ratio. By adjusting the duty cycles of multiple PWM signals rather than increasing clock frequency, the system achieves higher gray scale resolution. This parameter change allows precise control while maintaining lower operating frequencies that generate less electromagnetic interference.
3Adaptability or versatility
If a single driving current source is used, then the device complexity is low, but the brightness control range is limited
Solution Approach 1:
The patent segments the brightness control function across multiple parallel current sources, each capable of contributing different current levels. This allows the system to achieve a wider brightness control range by combining currents from different sources, while maintaining relatively simple individual source configurations.
Solution Approach 2:
The patent merges multiple driving current sources in parallel configuration to expand the overall brightness control range. By combining the output currents from the first, second, third, and fourth driving current sources, the system achieves a broader brightness spectrum while keeping each individual current source relatively simple in structure.
4Adaptability or versatility
If conventional LED display devices are used, then the device complexity is low, but the enlargement capability is limited
Solution Approach 1:
The patent segments the LED display into multiple independently controllable pixel units, each with its own set of driving current sources. This modular segmentation allows pixels to be arranged in various configurations to create displays of different sizes, enabling enlargement capability while maintaining manageable device complexity through standardized modular units.
Data Source
AI summary
The present disclosure relates to an LED driving technology. According to the present disclosure, it is possible to increase the fineness of the gray scale without increasing a frequency of a clock by combining a plurality of driving current sources to generate a driving current supplied to one driving line.