Endoscope Lighting Controller for Rolling Shutter Brightness
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Solution Overview
Problem
In endoscope systems using CMOS image sensors, uneven exposure times during rolling shutter mode can lead to brightness unevenness and deteriorated image quality due to differences in exposure periods across horizontal lines, especially in environments with limited external light.
Innovation Solution
An imaging system with a light source that controls illumination light emission independently during non-all-line and all-line exposure periods, using a combination of LEDs to adjust light amounts and pulse widths to ensure consistent illumination across all lines, thereby minimizing exposure time disparities and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rolling shutter mode is used to read out electric signals sequentially on a horizontal-line basis, then the reading circuit can simplify the reading process, but brightness unevenness occurs due to different exposure times among horizontal lines
Solution Approach 1:
The illumination light emission is dynamically controlled to match the exposure timing of different horizontal lines. The light source emits light during the non-all-line exposure period when specific lines are being exposed, ensuring that all lines receive consistent illumination despite the sequential reading process.
Solution Approach 2:
The illumination light is emitted in advance during the non-all-line exposure period before the all-line exposure period begins. This preliminary illumination ensures that lines being read out sequentially receive adequate light exposure, preventing brightness unevenness while maintaining the simplified rolling shutter reading process.
2Illumination intensity
If illumination light is continuously emitted to all lines, then all horizontal lines receive sufficient light, but brightness unevenness occurs because lines are read out at different times
Solution Approach 1:
The exposure period is segmented into a non-all-line exposure period and an all-line exposure period. During the non-all-line exposure period, illumination is targeted specifically at lines that are currently being exposed, while during the all-line exposure period, all lines receive illumination simultaneously. This segmentation ensures uniform brightness across all lines.
Solution Approach 2:
The illumination strategy is adjusted locally for different time periods and different horizontal lines. During the non-all-line exposure period, light is emitted specifically for the lines being exposed at that moment, while during the all-line exposure period, illumination is provided to all lines. This local adaptation of illumination quality eliminates brightness unevenness.
3Manufacturing precision
If the exposure period is extended to ensure all lines are exposed, then complete coverage is achieved, but time consumption increases due to sequential reading
Solution Approach 1:
The illumination light emission continues throughout both the non-all-line exposure period and the all-line exposure period without interruption. This continuous illumination ensures that all horizontal lines receive adequate light exposure while the sequential reading process proceeds efficiently, minimizing time loss while maintaining complete exposure coverage.
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 system effectively reduces brightness unevenness and enhances image quality by ensuring consistent illumination across all lines, preventing the occurrence of fringes and improving the overall image quality in endoscope applications.
Implementation Method 1
a light source for emitting illumination light with which a subject is irradiated
Implementation Method 2
pixels for generating electric signals by receiving light from the subject and performing photoelectric conversion on the received light
Data Source
AI summary
An imaging system includes a lighting controller for independently controlling emission of illumination light to be emitted by a light source in: (i) a non-all-line exposure period, which contains a reading period in which electrical signals are sequentially read out on a horizontal-line basis from an image sensor for one frame or one field period, and in which at least one horizontal line of the horizontal lines for the one frame or the one field period is not exposed to light, and (ii) in an all-line exposure period, in which all of the horizontal lines for the one frame or the one field period are exposed to light.