Endoscope Light Source Timing for Rolling Shutter Image Uniformity
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Solution Overview
Problem
Existing endoscope systems using rolling shutter type image sensors face issues with insufficient light amount, brightness unevenness, and horizontal stripes due to varying exposure periods, and offset light emission during the rolling shutter period leads to unnatural images.
Innovation Solution
A light source device with a light source control unit that divides the frame period into N dimming sections and controls light emission intensity in units of 2k sections to ensure a sufficient light amount while minimizing brightness unevenness and horizontal stripes, using bit shift calculation to execute dimming control without additional CPU resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light source is completely turned off during the rolling shutter period, then distortion and artifacts caused by rolling shutter are avoided, but the light amount becomes insufficient and satisfactory images cannot be acquired
Solution Approach 1:
The frame period is divided into multiple dimming sections (N sections where N is an integer of 2m), allowing different light emission intensities to be applied to different time segments. This segmentation enables the light source to emit at full intensity during global exposure period while controlling intensity during rolling shutter period, resolving the contradiction between sufficient light amount and avoiding rolling shutter artifacts.
Solution Approach 2:
The light emission intensity is dynamically adjusted based on the imaging period. The system transitions from static on/off control to dynamic intensity modulation, where the light source emits at different intensities during different phases of the frame period (global exposure vs. rolling shutter), optimizing both image quality and light efficiency.
2Illumination intensity
If offset light emission is performed during the rolling shutter period to solve light amount insufficiency, then the light amount is sufficient, but unnatural images like double exposure occur
Solution Approach 1:
Different light emission intensities are applied to different time segments (dimming sections) within the frame period. The light source emits at high intensity during global exposure period and controlled/reduced intensity during rolling shutter period, creating local quality variations in time that prevent double exposure while ensuring sufficient overall light amount.
3Illumination intensity
If the pulsed light emission period changes to ensure sufficient light amount, then the light amount is sufficient, but brightness unevenness and horizontal stripes occur and move on the display screen
Solution Approach 1:
By dividing the frame period into N dimming sections and controlling light emission in units of 2k sections, the system achieves precise control over the pulsed light emission period. This segmentation allows the total light amount to be sufficient while maintaining consistent exposure timing relative to the rolling shutter, preventing brightness unevenness and horizontal stripe artifacts.
4Ease of operation
If additional CPU resources are allocated to execute complex dimming control, then precise dimming control can be achieved, but device complexity and resource requirements increase
Solution Approach 1:
The patent replaces complex CPU-based control with a simpler light source control unit that uses bit shift calculations for dimming control. This substitution of control mechanism reduces computational requirements and device complexity while maintaining precise dimming control capability.
Solution Approach 2:
The system changes the control parameter from complex temporal intensity modulation to simple bit shift-based dimming levels. By representing dimming sections as powers of 2 (2k where k is an integer from 0 to m), the control becomes computationally efficient and can be executed with minimal resources.
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
Ensures a sufficient light amount while avoiding distortion and artifacts caused by a rolling shutter, making brightness unevenness and horizontal stripes less noticeable, and reducing the risk of double exposure-like images.
Implementation Method 1
a semiconductor light emitting element that emits light
Data Source
AI summary
The light source device includes a semiconductor light emitting element that emits light, and a light source control unit that generates an emission profile of the semiconductor light emitting element and drives the semiconductor light emitting element on the basis of the emission profile. The light source control unit executes: processing of dividing one frame period in an image signal acquired by an image sensor into N (N is an integer of 2m, m being an integer of 2 or more) dimming sections; processing of generating an emission profile for controlling light emission intensity in units of 2k (k is an integer from 0 to m) dimming sections according to a target light amount in one frame period; and processing of performing dimming control for a next frame on the basis of the emission profile.