LED Array Driver With Dynamic Headroom Feedback Control
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Solution Overview
Problem
Existing LED driver circuits for segmented arrays are inefficient due to high power consumption, complexity, and size issues, making them unsuitable for mobile devices, and they often cannot drive all LED segments simultaneously while maintaining optimal voltage headroom.
Innovation Solution
A driver circuit with a voltage converter and current regulators that adjusts supply voltage based on feedback from window comparators monitoring LED cathode voltages, minimizing power dissipation and allowing simultaneous operation of all LED segments with reduced device size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback-controlled current source is used to drive segmented LED array, then correct operation of each LED is ensured, but power consumption becomes high and battery depletes rapidly
Solution Approach 1:
The patent implements dynamic headroom adjustment by monitoring the actual voltage headroom required by LED segments and adjusting the voltage converter output accordingly. Instead of maintaining a fixed large voltage headroom, the system dynamically reduces the headroom to the minimum necessary level, thereby reducing power consumption while ensuring correct LED operation.
Solution Approach 2:
The patent employs feedback control by monitoring the voltage headroom of individual LED segments and using this information to adjust the overall supply voltage. The monitoring arrangement provides feedback signals that enable the voltage converter to optimize the voltage headroom, balancing reliable LED operation with reduced power consumption.
2Reliability
If voltage headroom is increased to ensure correct LED operation, then LED reliability improves, but power consumption increases
Solution Approach 1:
The patent changes the voltage headroom parameter dynamically based on actual LED requirements. By monitoring the forward voltage of individual LED segments and adjusting the supply voltage accordingly, the system maintains the minimum necessary headroom for reliable operation while minimizing excess voltage headroom that would cause unnecessary power dissipation.
3Reliability
If complex driver circuit is used to monitor and control voltage headroom, then LED operation is optimized, but device size and manufacturing cost increase
Solution Approach 1:
The patent merges the voltage headroom monitoring function with the existing LED driver circuitry. The monitoring arrangement is integrated into the driver, and the same control infrastructure is used to adjust the voltage converter, thereby achieving LED optimization without proportionally increasing device complexity and size.
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
The solution optimizes power efficiency, reduces device size, and enables simultaneous driving of all LED segments with minimal power consumption, addressing the inefficiencies and complexity of prior art while allowing for compact integration in mobile devices.
Implementation Method 1
a voltage converter (10) arranged to generate a supply voltage to the LED array and to adjust the supply voltage in response to a feedback signal
Implementation Method 2
a monitoring arrangement (M) adapted to monitor voltages of the currents relative to a predefined range or 'voltage headroom' and to generate the feedback signal on the basis of the headroom monitoring results. The monitoring arrangement comprises a plurality of window comparators
Implementation Method 3
A segmented LED array may comprise several light-emitting diodes, each of which illuminates a part of the field
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention describes a driver (1) of an array (2) of current-driven LEDs (20), comprising a voltage converter (10) arranged to generate a supply voltage (Vboost) to the LED array (2) and to adjust the supply voltage (Vboost) in response to a feedback signal (100); a number of current sources (CS1,..., CSn) arranged to drive the LEDs (20) of the LED array (2); and a monitoring arrangement (M) adapted to monitor a current source voltage (Vcs1,..., Vcsn) relative to a voltage headroom (H) and to generate the feedback signal (100) on the basis of the headroom monitoring results. The invention further describes a device (4) comprising an LED array (2) and an embodiment of the inventive driver (1). The invention further describes method of driving an LED array (2).