Rolling-Shutter CMOS Sensor Light Reception Control
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Solution Overview
Problem
Rolling-shutter type CMOS image sensors in imaging devices face challenges in achieving sufficient image quality and frame rate for medical endoscope applications due to uneven light receiving periods across pixels, leading to potential distortion and inadequate image quality for observation.
Innovation Solution
The imaging device controls the exposure and light reception periods of CMOS image sensors to ensure that pixels receive light only during the blanking period or a period centered on the blanking period, allowing for a reduced read period and improved frame rate, thereby enhancing image quality and preventing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rolling shutter type CMOS image sensor is used to reduce cost and power consumption, then manufacturing cost and energy efficiency are improved, but uneven light receiving periods across pixels cause image distortion and insufficient image quality
Solution Approach 1:
The patent implements periodic action by controlling the light source to emit light in specific time intervals that correspond to the rolling shutter readout periods. The exposure periods of pixels are synchronized with periodic light emission cycles, ensuring that all pixels receive light during their respective readout windows. This periodic synchronization eliminates image distortion while maintaining the cost advantages of rolling shutter CMOS sensors.
2Productivity
If the read period is reduced to improve frame rate, then productivity is improved, but the exposure period becomes insufficient leading to inadequate light reception and poor image quality
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing the light source emission timing with the predicted exposure periods of pixels before the actual exposure occurs. The control unit calculates and sets the light emission schedule in advance based on the rolling shutter readout timing, ensuring that sufficient light is available when each pixel group needs to expose. This allows for reduced read periods and improved frame rates while maintaining adequate light reception.
3Measurement precision
If the exposure period is extended to improve image quality, then measurement precision is improved, but the frame rate decreases due to increased total imaging time
Solution Approach 1:
The patent applies segmentation by dividing the image sensor into multiple pixel groups that are read out sequentially in different time intervals. Each pixel group has a dedicated exposure period that is optimized for sufficient light reception. By segmenting the readout process and synchronizing light emission with each segment's exposure window, the system achieves adequate exposure times for good image quality while maintaining high frame rates through parallel processing of different pixel groups.
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 ensures sufficient image quality and frame rate for medical observations by reducing the exposure period of image sensors and optimizing light reception, resulting in improved image clarity and reduced distortion.
Implementation Method 1
a plurality of pixels arranged in a matrix to generate electric signals due to light received
Data Source
AI summary
An imaging device according to an embodiment includes an image sensor, and processing circuitry. The image sensor is a rolling-shutter type image sensor that includes a plurality of pixels that are arranged in a matrix and generate an electric signal due to light received and, on a frame-to-frame basis, repeatedly performs a process to sequentially start to conduct exposure on at least every line, starting from the first line of the pixels to the last line, and output the electric signal sequentially from the line for which exposure has been completed. The processing circuitry causes the pixels to receive light during only a period based on the blanking period that corresponds to the period from when the output of the electric signal from the last line is finished until the output of the electric signal from the first line is started. The processing circuitry generates images in accordance with the electric signal.