Semiconductor Light Emitting Element Drive Current Control
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Solution Overview
Problem
Semiconductor light emitting elements, such as lasers and LEDs, experience variations in light intensity due to temperature changes, leading to inconsistencies in image display, particularly in projectors, as the threshold current varies with temperature, affecting the emission amount and luminance distribution.
Innovation Solution
A light source device with a control section that supplies a drive current based on an input value and an estimated threshold current, using a threshold current estimator to adjust the drive current and maintain consistent light intensity, thereby compensating for temperature-induced variations in the semiconductor light emitting element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a semiconductor light emitting element is used as a light source, then the device can be compact and efficient, but the light intensity varies due to heat generation and temperature changes
Solution Approach 1:
The patent implements a feedback control mechanism where a light receiving element detects the actual light output from the semiconductor light emitting element, and a control circuit adjusts the drive current to compensate for deviations from the target light intensity. This closed-loop feedback system maintains stable light output despite temperature variations and heat generation.
Solution Approach 2:
The patent dynamically adjusts the drive current parameter based on detected light intensity and temperature conditions. By changing the electrical input parameter (drive current) in response to environmental changes, the system maintains consistent light output performance.
2Illumination intensity
If the drive current is increased to compensate for threshold current variation, then the light intensity can be maintained, but the heat generation increases further
Solution Approach 1:
The feedback control mechanism monitors actual light output and makes precise adjustments to drive current only when necessary to maintain target intensity. This prevents excessive current increases that would cause overheating, as the system responds proportionally to actual deviations rather than over-compensating.
Solution Approach 2:
The patent replaces thermal management mechanisms with an electrical control mechanism. Instead of using heat sinks or cooling systems to manage temperature, the system uses electronic feedback to adjust electrical parameters, avoiding the heat generation associated with aggressive thermal compensation.
3Measurement precision
If a threshold current estimation mechanism is added, then the drive current can be adjusted accurately, but the device complexity increases
Solution Approach 1:
The system uses the semiconductor light emitting element itself to generate the estimation information needed for control. By monitoring the relationship between drive current and actual light output, the system self-determines threshold current characteristics without requiring external measurement equipment or complex separate estimation circuits.
Solution Approach 2:
The light receiving element serves multiple functions: it detects light intensity for feedback control and simultaneously provides information for threshold current estimation. This multi-functionality reduces overall system complexity by eliminating the need for separate estimation hardware.
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 ensures that the semiconductor light emitting element accurately outputs light intensity corresponding to the input value, even with temperature variations, resulting in consistent image luminance and reduced luminance distribution issues.
Implementation Method 1
a semiconductor light emitting element capable of emitting light
Implementation Method 2
the intensity or amount of light emitted from the semiconductor laser can vary due to heat generation
Implementation Method 3
This phenomenon is particularly prominent in configurations where the semiconductor laser uses the thermal lens effect
Data Source
AI summary
A light source device including a semiconductor light emitting element and a control section for controlling the semiconductor light emitting element in accordance with an input value. The control section includes a supply section that supplies the semiconductor light emitting element with a drive current based on the input value and an estimated threshold current of the semiconductor light emitting element, and an estimation section that obtains the estimation of the threshold current using the drive current and the amount of light detected to be emitted from the semiconductor light emitting element.