LED Driver Temperature Compensation via Forward Voltage
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Solution Overview
Problem
Conventional LED driving apparatuses for LCD backlight units require expensive optical sensors to compensate for luminance variations due to temperature changes, increasing installation space and manufacturing costs, and limiting design flexibility.
Innovation Solution
An LED driving apparatus that uses a reference voltage generator, non-inversion amplification unit, and forward voltage detector to adjust the supply voltage based on the forward voltage of the LED light source, eliminating the need for optical or temperature sensors, and incorporating an on/off switch and current limiter to maintain constant luminance across temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical sensors are used to compensate for luminance variations, then temperature compensation capability is improved, but manufacturing cost and installation space increase
Solution Approach 1:
The patent extracts the temperature sensing function from the LED itself by utilizing its forward voltage characteristic, eliminating the need for separate optical or temperature sensors. The forward voltage detector directly measures the forward voltage of the LED, which inherently reflects temperature changes, thereby removing complex external sensing components while maintaining temperature compensation capability.
Solution Approach 2:
The LED light source serves its own temperature sensing function through its forward voltage characteristic. The forward voltage of the LED naturally varies with temperature, and the patent utilizes this self-generated signal for temperature compensation, eliminating the need for external sensors and reducing system complexity.
2Measurement precision
If optical sensors are used to monitor light quantity, then luminance control precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive optical sensors with a simple forward voltage detection circuit that has no moving parts and minimal components. The forward voltage detector uses basic electronic components to measure voltage, providing a cost-effective solution that maintains measurement capability without the high manufacturing cost of optical sensors.
Solution Approach 2:
The patent substitutes optical sensing with electrical sensing. Instead of using optical sensors to detect light output, the system uses electrical voltage measurement of the LED's forward voltage to infer temperature and control luminance, replacing complex optical-mechanical systems with simple electrical measurement circuits.
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
This solution effectively compensates for temperature-induced luminance variations without optical or temperature sensors, reducing installation space and manufacturing costs while promoting design flexibility and maintaining consistent LED brightness.
Implementation Method 1
a forward voltage detector for detecting the forward voltage at an anode of the light emitting diodes of the light source to supply the forward voltage to the non-inversion amplification unit
Implementation Method 2
a non-inversion amplification unit for performing non-inversion amplification to a difference voltage between the first reference voltage and a forward voltage with a preset gain
Implementation Method 3
a driving unit for adjusting a supply voltage in response to the voltage from the non-inversion amplification unit to supply the adjusted supply voltage to a light source having light emitting diodes
Implementation Method 4
a reference voltage generator for generating a first reference voltage
Data Source
AI summary
An LED driving apparatus having a temperature compensation function includes a reference voltage generator for generating a first reference voltage and a non-inversion amplification unit for performing non-inversion amplification to a difference voltage between the first reference voltage and a forward voltage with a preset gain. A driving unit adjusts a supply voltage in response to the voltage from the non-inversion amplification unit to supply the adjusted supply voltage to a light source having light emitting diodes. A forward voltage detector detects the forward voltage at an anode of the light emitting diodes of the light source to supply the forward voltage to the non-inversion amplification unit. Luminance variation can be compensated according to temperature changes by using a forward voltage of an LED light source so that the forward voltage of the LED light source can be controlled in association with a target current value of ambient temperature.