Optical Mouse Image Capture Chip Exposure Control Logic
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Solution Overview
Problem
Conventional image capture chips face difficulties in efficiently adjusting exposure parameters to converge the exposure value within a normal range, often requiring numerous adjustment steps due to the challenge of defining a suitable predetermined exposure parameter, leading to issues with image quality from excessive darkness or brightness.
Innovation Solution
An image capture chip comprising an image sensor, a calculating logic circuit, and a refreshing logic circuit that calculates and adjusts exposure parameters based on exposure ranges, determining whether the captured image meets image quality conditions to rapidly adjust exposure values within the normal-exposure range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the exposure parameter is adjusted with an excessively large predetermined exposure parameter, then the exposure value can be adjusted quickly, but the illumination of a digital image is substantially changed resulting in excessive darkness or brightness
Solution Approach 1:
The patent divides the exposure adjustment process into multiple stages: initial rapid adjustment using larger parameter changes, followed by fine-tuning using smaller parameter changes. This segmentation allows the system to first converge quickly to near-optimal exposure values, then precisely adjust to achieve normal illumination without excessive darkness or brightness.
Solution Approach 2:
The patent dynamically adjusts the exposure parameter based on the current exposure value state. When the exposure value is far from the normal range, larger parameter changes are applied for rapid convergence. As the exposure value approaches the normal range, smaller parameter changes are applied for precise control, making the adjustment process adaptive rather than static.
2Manufacturing precision
If the exposure parameter is adjusted by an excessively small predetermined exposure parameter, then the illumination of the object is changed slightly maintaining image quality, but numerous adjustment steps are required resulting in slow convergence
Solution Approach 1:
The adjustment process is segmented into coarse adjustment phase and fine adjustment phase. During the coarse phase, larger parameter steps are used to quickly reduce the gap between current and target exposure values. During the fine phase, smaller parameter steps are used to precisely achieve the target exposure value, optimizing both speed and precision.
Solution Approach 2:
The patent changes the adjustment parameter magnitude based on the exposure value deviation from the normal range. When deviation is large, larger parameter changes are applied. When deviation is small, smaller parameter changes are applied. This dynamic parameter change strategy optimizes both convergence speed and final precision.
3Device complexity
If the exposure value is not converged within the normal-exposure range, then the adjustment process is simple, but the image quality is adversely affected due to excessive darkness or brightness
Solution Approach 1:
The patent implements a feedback mechanism where the exposure value is continuously monitored and compared against the normal exposure range. Based on this feedback, the system automatically adjusts the exposure parameter in subsequent frames to converge the exposure value within the normal range, ensuring image quality without requiring complex manual intervention.
Solution Approach 2:
The exposure adjustment system is self-regulating, automatically detecting when exposure values fall outside the normal range and correcting them without external intervention. The system serves itself by using its own output (exposure values) to control its input (exposure parameters), maintaining image quality autonomously.
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 solution enables rapid convergence of exposure values within the normal-exposure range with fewer adjustment steps, improving image quality by dynamically adjusting exposure parameters and maintaining them if the image quality meets specified conditions, even in over- or under-exposure ranges.
Implementation Method 1
If a CMOS M2 is turned on according to a reset signal RES, the potential across an optical diode PD is charged to a voltage Vrst
Implementation Method 2
Each row of sensor units PIX1m ∼PIXnm as shown in FIG. 1A comprises its storage 131. When a NMOS M3 is turned on by a select signal RSEL2, the residual voltage across the optical diode PD is transformed into a current across an NMOS M1
Data Source
AI summary
An optical mouse and image capture chip thereof. The image capture chip comprises an image sensor, a calculating logic circuit, and a refreshing logic circuit. The image sensor has a plurality of sensor units, capturing an image according to an exposure parameter to provide a plurality of exposure values. The calculating logic circuit provides an average exposure value by calculating the exposure values. If the exposure sample is within a first exposure range, the refreshing logic circuit maintains the exposure parameter and accordingly drives the image sensor to capture a next image. If the average exposure value is within a second exposure range, the refreshing logic circuit adjusts the exposure parameter with a first exposure extreme and accordingly drives the image sensor to capture a next image. If the average exposure value is within a third exposure range, the refreshing logic circuit adjusts the exposure parameter with a second exposure extreme and accordingly drives the image sensor to capture a next image.