LED Dimming Controller Using Packeted Pulse Width Modulation
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Solution Overview
Problem
Existing light-emitting diode (LED) dimming technologies using pulse width modulation (PWM) often result in the 'string of pearls' effect and insufficient dimming resolution, particularly in high-density matrix systems like vehicle headlights, where glare and visibility issues arise due to limited dimming precision.
Innovation Solution
Implementing a controller that actuates LEDs in packets of varying or constant clock pulses to achieve finer dimming steps and mitigate the 'string of pearls' effect, allowing for increased brightness modulation resolution by adjusting pulse durations within packets based on movement speed detected by sensors like cameras or radar systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PWM dimming is used with standard 6-bit resolution (64 levels), then the control system is simple and operates at acceptable PWM frequency (250 Hz), but the dimming resolution is insufficient (1.5% increments) causing visible gratings and glare
Solution Approach 1:
The patent segments the dimming control into multiple packets of clock pulses instead of using a single long packet. By dividing the control into smaller temporal segments (packets), the system achieves higher effective resolution through statistical averaging while keeping individual packet processing simple and manageable.
Solution Approach 2:
The patent employs periodic action by using multiple clock pulses arranged in packets with specific duty cycles. The controller alternates between different duty cycles across multiple periods (packets), creating a time-averaged dimming effect that achieves higher resolution than any single period could provide alone.
2Measurement precision
If high PWM frequency (250 Hz) is used to prevent flickering, then the string of pearls effect is minimized, but the dimming resolution becomes insufficient due to the limited number of dimming levels per period
Solution Approach 1:
The patent transitions from controlling brightness within a single time period to controlling brightness across multiple time periods (packets). By adding the temporal dimension of multiple packets, the system achieves higher resolution dimming control without changing the PWM frequency, effectively moving the problem from one-dimensional (single period) to multi-dimensional (multiple periods) control space.
Solution Approach 2:
The patent performs preliminary action by pre-calculating and storing multiple packet patterns with different duty cycle combinations in a lookup table. This allows the controller to select pre-computed patterns that achieve the desired dimming level with high resolution, rather than calculating optimal duty cycles in real-time during operation.
3Measurement precision
If uniform pulse durations are used within packets, then the control logic is simplified, but the dimming resolution remains limited to standard 6-bit levels
Solution Approach 1:
The patent introduces dynamics by allowing pulse durations within packets to vary based on the selected operating mode. The controller can dynamically switch between first operating mode (uniform pulse durations for simplicity) and second operating mode (varying pulse durations for higher resolution), adapting the control strategy to the specific dimming requirements.
Solution Approach 2:
The patent changes parameters by varying the duty cycles of individual clock pulses within packets according to different operating modes. By modifying the pulse duration parameter across multiple packets, the system achieves higher effective resolution while maintaining manageable control logic through predefined mode selections.
4Measurement precision
If more dimming levels are implemented beyond 6-bit resolution, then the dimming precision improves, but the clock pulse duration becomes too short to be effectively controlled
Solution Approach 1:
The patent segments the total dimming control period into multiple smaller packets, each containing multiple clock pulses. By distributing the high-resolution dimming control across multiple segments rather than attempting to achieve it within a single clock period, the system maintains adequate pulse durations for effective control while achieving the desired resolution through the cumulative effect of multiple segments.
Data Source
AI summary
A light-emitting diode assembly having at least one light-emitting diode, a controller which is designed to dim the at least one light-emitting diode by means of pulse width modulation, wherein the pulse width modulation is characterized by a clock pulse and a pulse duration during a clock pulse. The controller is designed to actuate the at least one light-emitting diode with packets of at least two clock pulses. The controller being optionally designed to actuate the at least one light-emitting diode in a first operating mode and at least one second operating mode, wherein the at least one light-emitting diode is actuated in the first operating mode with the same pulse durations within the packet and is actuated in the second operating mode with at least one different pulse duration within the packet.