Self-Referencing Current Source for LED Display Precision

The patent divides the current driving function into multiple independent current source circuits, each responsible for a specific pixel or group of pixels. This segmentation allows each circuit to independently compensate for local variations and IR drop effects, improving LED output consistency without requiring a completely complex global control system.

The patent implements local current reference generation at or near each pixel location, allowing each pixel's current source to be independently optimized. This local quality approach enables compensation for position-dependent IR drop and component variations, achieving high manufacturing precision while keeping individual circuit blocks relatively simple.

The patent employs pulse width modulation (PWM) to control LED intensity, where the LED is driven at a high frequency with varying duty cycles. This periodic action allows intensity control without continuous voltage adjustment, preventing wavelength shifts and maintaining color consistency while preserving ease of operation through digital-like control.

The patent preemptively prevents color shift by avoiding voltage modulation that causes wavelength changes. Instead, the system uses current modulation through PWM, which controls intensity without affecting the LED's forward voltage and thus preventing the harmful effect of color instability.

The patent optimizes the current magnitude and pulse width parameters to achieve the required LED brightness and precision with minimal energy consumption. By carefully selecting operating parameters and using efficient PWM control, the system achieves high output precision while minimizing I²R losses and overall power consumption.

The use of PWM allows the LED to be driven in short high-current pulses rather than continuous current, achieving the required light output precision while significantly reducing average power consumption and I²R losses compared to continuous high current driving.