LED String Current Control for Heat Reduction
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Solution Overview
Problem
In liquid crystal display (LCD) devices using local dimming methods with LEDs, the multi-channel current control circuit consumes voltage deviations as power, leading to heat-related damage to circuit elements.
Innovation Solution
A method and apparatus that switch-control peak currents due to voltage deviations in light source strings connected in parallel to maintain uniform average currents, preventing power consumption of voltage deviations and thus reducing heat-related damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-channel current control circuit is used to control driving currents flowing through LED strings, then uniform current control is achieved, but voltage deviation is consumed as power causing heat damage to circuit elements
Solution Approach 1:
The patent extracts the harmful voltage deviation from the current control process by using separate current control circuits for each LED string that independently regulate current without relying on voltage balancing. This removes the source of heat generation while maintaining uniform current control across all strings
Solution Approach 2:
The patent divides the backlight assembly into multiple independent LED strings with separate current control circuits, allowing each string to be controlled independently. This segmentation eliminates the need for a complex multi-channel current control circuit that consumes voltage deviation, thereby reducing heat generation while maintaining uniform current distribution
2Illumination intensity
If local dimming method is used to control light amounts in different areas, then contrast ratio is improved, but complex current control circuits are required
Solution Approach 1:
The patent divides the backlight assembly into multiple independent LED strings that can be individually controlled for local dimming. Each string has its own simple current control circuit, avoiding the need for a complex multi-channel control circuit while achieving the desired contrast ratio improvement through selective dimming of different areas
Data Source
AI summary
A method of driving a light source, a light source apparatus for performing the method, and a display apparatus having the light source apparatus are disclosed in accordance with one or more embodiments. In the method, a plurality of light source strings connected in parallel is driven by applying a driving voltage to a first terminal of the light source strings. A peak current due to a voltage deviation of each of the light source strings is switch-controlled to uniform an average current of the light source strings. Thus, a peak current flowing through light source strings in accordance with a voltage deviation of the light source strings is switch-controlled, so that an average current of the light source strings may be uniformly maintained. Therefore, a voltage deviation is not consumed as power, so that damage to circuit elements due to heat may be prevented.