Optical Sensor Exposure Control for Wide Dynamic Range Light Source
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Solution Overview
Problem
Conventional light source devices for endoscopes face challenges in detecting a wide range of light intensities, particularly in achieving a dynamic range that spans several thousand times between maximum and minimum light quantities, which is necessary for adjusting color balance, but usual optical sensors lack the required wide detection range.
Innovation Solution
A light source device employing semiconductor light sources, controlled by pulse width modulation, with an optical sensor that detects light in an exposure period shorter than the minimum pulse width, allowing for precise adjustment of emission intensity and achieving a wide dynamic range without the need for multiple optical sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a usual optical sensor is used to detect light quantity, then the device complexity is reduced, but the detection range is insufficient to cover several thousand times between maximum and minimum light quantities
Solution Approach 1:
The detection process is segmented into multiple exposure periods with different exposure times. The sensor control section divides the detection into a first exposure period (long exposure time) for detecting minimum light quantity and a second exposure period (short exposure time) for detecting maximum light quantity. This segmentation allows a single optical sensor to cover a wide dynamic range by capturing different light intensity levels at different times.
Solution Approach 2:
The sensor control section implements periodic action by alternating between different exposure periods. The optical sensor repeatedly switches between long exposure time mode and short exposure time mode, allowing it to periodically capture both minimum and maximum light quantities. This periodic switching enables the single sensor to handle the full dynamic range required for color balance adjustment across several thousand times variation in light intensity.
2Measurement precision
If the optical sensor uses a long exposure time to detect minimum light quantity, then the detection sensitivity is improved, but the maximum detectable light quantity is reduced due to sensor saturation
Solution Approach 1:
The optical sensor operates dynamically by changing its exposure time based on the light quantity being detected. The sensor control section adjusts the exposure time between a first exposure period (long duration for minimum light detection) and a second exposure period (short duration for maximum light detection). This dynamic adjustment of exposure time allows the sensor to adapt its sensitivity range, enabling it to detect both very low and very high light intensities without saturation or excessive noise.
3Measurement precision
If multiple optical sensors with different detection ranges are used to cover the full dynamic range, then the detection precision across all light quantities is improved, but the device complexity and cost increase
Solution Approach 1:
The single optical sensor is designed to perform multiple functions by detecting different light quantity ranges at different exposure periods. The sensor control section enables the same sensor to function as both a high-sensitivity detector for minimum light quantity (using long exposure time) and a high-capacity detector for maximum light quantity (using short exposure time). This multi-functionality eliminates the need for multiple specialized sensors, reducing device complexity and cost while maintaining detection precision across the full dynamic range.
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 enables accurate detection and adjustment of light intensities across a wide range, allowing for precise color balance and modulation, reducing costs by eliminating the need for multiple optical sensors while maintaining high sensitivity.
Implementation Method 1
an optical sensor that receives the light emitted from the semiconductor light source to acquire a quantity of the received light
Implementation Method 2
a semiconductor light source; a light source control section that controls a light quantity per field of light to be emitted from the semiconductor light source
Data Source
AI summary
A light source device includes a semiconductor light source, a light source control section, an optical sensor, a sensor control section, and an intensity adjusting section. The light source control section controls a light quantity per field of light to be emitted from the semiconductor light source, by pulse width modulation. The optical sensor receives the light emitted from the semiconductor light source to acquire a quantity of the received light. The sensor control section controls the optical sensor to detect the light in an exposure period shorter than a minimum pulse width in the pulse width modulation, thereby acquiring the quantity of the received light which is acquired by the optical sensor. The intensity adjusting section adjusts emission intensity of the semiconductor light source on the basis of the quantity of the received light.