Endoscope CMOS Sensor Reset Timing for Wide Dynamic Range
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Solution Overview
Problem
Conventional endoscope systems using CMOS image sensors face challenges in achieving wide dynamic range and optimal image visibility due to time differences in signal occurrence between horizontal lines, leading to afterimages and reduced visibility of weak light emissions like fluorescence.
Innovation Solution
The endoscope system adjusts the timing of generating reset pulses to include multiple frame cycles between consecutive reset pulses, allowing for extended accumulation of electric charges without changing the frame rate, and dynamically adjusts reset timing based on image brightness and illumination conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reset pulses are generated at conventional timing in CMOS image sensors, then the frame rate is maintained, but the dynamic range is limited and afterimages occur due to time differences in signal occurrence between horizontal lines
Solution Approach 1:
The reset pulse generation timing is made dynamic rather than fixed. The controller adjusts the reset pulse timing based on the specific imaging conditions and requires that at least a part of multiple frame cycles be included between consecutive reset pulses, allowing the system to adaptively optimize for different scenarios while maintaining reliable image quality
Solution Approach 2:
The patent changes the temporal parameter of reset pulse generation by extending the interval between consecutive reset pulses to span multiple frame cycles. This parameter change allows electric charges to be accumulated for longer periods, thereby expanding the dynamic range and reducing afterimages while the system maintains the original frame rate for display
2Measurement precision
If the accumulation period of electric charges is extended to improve dynamic range, then visibility of weak light emissions is enhanced, but the frame rate may be affected
Solution Approach 1:
The patent segments the frame cycles into multiple intervals between consecutive reset pulses. By requiring that at least a part of multiple frame cycles be included in this period, the system divides the imaging process into distinct accumulation phases, allowing extended charge accumulation for improved detection sensitivity while maintaining the overall frame rate through proper timing coordination
Solution Approach 2:
The reset pulse generation follows a periodic pattern where multiple frame cycles are included between consecutive reset pulses. This periodic extension of the accumulation period enables enhanced detection of weak light emissions while the periodic nature ensures that the overall frame rate remains consistent and predictable
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 approach enables the acquisition of images with a wide dynamic range and enhanced visibility of weak light emissions, reducing afterimages and maintaining a consistent frame rate, thereby improving the detection of fluorescent images without causing unnatural flickering.
Implementation Method 1
a sensor unit having a two-dimensional surface on which a plurality of pixels is arranged for receiving the return light from the visual field area and photoelectrically converting the return light to generate electrical signals
Data Source
AI summary
An endoscope system includes: an illumination unit configured to irradiate a visual field area with illumination light that produces return light from a specific substance; a sensor unit having a two-dimensional surface on which a plurality of pixels is arranged for receiving the return light from the visual field area and photoelectrically converting the return light to generate electrical signals; a reading unit configured to read out the electrical signals per a specified frame cycle; a reset pulse generation unit configured to generate reset pulses for releasing electric charges accumulated in the plurality of pixels; a reset pulse controller configured to adjust timing of generating the reset pulses such that a plurality of frame cycles is included in a period between generation of two consecutive reset pulses; and an illumination controller configured to cause the illumination unit to emit the illumination light in each of the plurality of frame cycles.