CMOS Image Sensor Charge Reset for Endoscopic Imaging
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Solution Overview
Problem
CMOS image sensors in endoscopic apparatuses tend to distort and produce blurred images due to charge accumulation during the capture of quickly moving subjects, as they restart charging immediately after reading, leading to inconsistent image quality.
Innovation Solution
The endoscopic apparatus employs a CMOS image sensor with a camera control unit that resets charges by extinguishing the light source, allowing for simultaneous charge accumulation during still image pickup, and then reads the charges in a controlled manner to prevent distortion, using a switch to manage the image pickup operation and display on a monitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a CMOS image sensor is used to reduce manufacturing costs, then single-chip manufacturing costs are reduced, but image distortion and blurring occur due to charge restart after reading
Solution Approach 1:
The patent applies preliminary action by resetting charges in all pixels simultaneously before the actual image capture begins. This is achieved by turning off the light source and activating a reset signal that clears accumulated charges from every pixel at the same time, ensuring a uniform starting state for charge accumulation during the exposure period.
Solution Approach 2:
The patent implements periodic action through a cyclic operation sequence: charge accumulation during illumination, followed by charge reading, then charge resetting by turning off the light source. This periodic cycle ensures that each imaging frame starts with uniformly reset charges, preventing the distortion and blurring that would otherwise occur with continuous operation.
2Ease of operation
If charges are read sequentially from pixels, then reading operation can be performed, but image distortion and blurring occur due to charge restart during reading
Solution Approach 1:
The patent applies preliminary action by completing the charge reset operation before the reading phase begins. By turning off the light source and resetting all pixel charges to zero at the start of each frame, the system ensures that during the subsequent reading operation, no new charges are accumulated, thus preventing distortion while allowing sequential reading to proceed.
3Illumination intensity
If the light source remains on during charge reading, then continuous illumination is maintained, but charges continue to accumulate causing image blurring
Solution Approach 1:
The patent implements periodic action by switching the light source on during the charge accumulation phase and then turning it off during the charge reading and resetting phase. This periodic switching ensures that charge accumulation stops when reading begins, preventing over-exposure and image blurring, while still providing illumination during the exposure period.
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 method enables undistorted and non-blurred observation images to be captured, even with quickly moving subjects, by ensuring uniform charge reset and controlled illumination, thereby improving image quality and allowing for efficient sequential image pickup operations.
Implementation Method 1
An observation image formed by the objective lens is photoelectrically converted into an image signal by a solid image pickup device (for example, a CCD image sensor or a CMOS image sensor)
Data Source
AI summary
An endoscopic apparatus having an image pickup system operating as follows. Before picking up a still image in a body cavity that almost no light can reach, the system extinguishes LED and resets charges accumulated in respective pixels in a CMOS image sensor. In this reset state, the system illuminates LED and allows the CMOS image sensor to pick up a still image. While the charges are being read from the pixels, the system extinguishes LED and prevents further charges from being accumulated in the pixels from which the charges have not been read yet.