CMOS Sensor Internal Exposure Time Determination for Code Readers
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Solution Overview
Problem
Current CMOS sensor-based code readers experience slow response times due to iterative exposure time adjustments, leading to suboptimal image quality and increased consumption, as they rely on external systems to determine suitable exposure times, which are often not adapted quickly enough to varying conditions.
Innovation Solution
The method involves a CMOS sensor that internally determines an optimal exposure time by measuring image data at multiple exposure values distributed across the pixel matrix, using a sliding exposure mode to calculate the best exposure time based on statistical analysis of image histograms, allowing for quick acquisition and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If iterative image capture loop with external system is used to adapt exposure time, then image quality is improved, but response time increases significantly
Solution Approach 1:
The patent implements a measurement mode that performs preliminary exposure time determination before nominal image capture. The sensor quickly acquires measurement image data with different exposure time values, calculates histograms, and determines the desired exposure time in advance. This preliminary action eliminates the need for iterative loops during actual code reading, achieving both high image quality and fast response time.
Solution Approach 2:
The patent enables the sensor to autonomously determine optimal exposure time through internal histogram calculation and analysis. The sensor performs measurement image acquisition, calculates histograms for different exposure time values, compares them, and selects the desired exposure time without external system intervention. This self-service capability eliminates communication overhead and iterative loops, significantly reducing response time while maintaining image quality.
2Measurement precision
If multiple images are captured iteratively to determine optimal exposure time, then image quality is ensured, but power consumption increases
Solution Approach 1:
The patent performs exposure time determination in a preliminary measurement mode before actual code reading. The sensor quickly acquires measurement image data with different exposure time values, calculates histograms, and determines the optimal exposure time in advance. This preliminary action ensures that only a single nominal image needs to be captured at the optimal settings, eliminating repeated image captures and significantly reducing power consumption.
Solution Approach 2:
The patent uses subsampling of matrix rows during measurement image acquisition to reduce the amount of data processed. By selecting only certain rows for histogram calculation instead of processing the entire image, the patent achieves sufficient exposure time determination with reduced computational effort and lower power consumption, while still ensuring accurate image quality.
3Device complexity
If preset exposure time value is used without adaptation, then device complexity is reduced, but image quality becomes suboptimal under varying conditions
Solution Approach 1:
The patent implements an automated measurement mode that enables the sensor to self-determine optimal exposure time through internal histogram calculation and analysis. The sensor autonomously compares histograms for different exposure time values and selects the desired exposure time without requiring external system intervention or complex iterative loops. This self-service approach maintains simple device architecture while ensuring optimal image quality under varying lighting conditions.
Solution Approach 2:
The patent dynamically adjusts the exposure time parameter based on real-time histogram analysis of measurement image data. By changing the exposure time parameter from preset fixed values to dynamically determined values based on actual lighting conditions, the patent achieves optimal image quality without increasing overall device complexity. The measurement mode enables adaptive parameter selection while maintaining simple hardware architecture.
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 significantly reduces the response time of the code reader, enhances image quality, and decreases consumption by allowing for real-time adaptation of exposure times within the sensor, resulting in improved ergonomics and reduced power usage.
Implementation Method 1
pixel structure with photosensitive element and control transistors
Data Source
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AI summary
The invention proposes a method of image acquisition of a target code which allows the CMOS sensor, after triggering of the reader for the acquisition of a target code, to determine rapidly, and internally, a desirable value Topt of exposure time for capturing an image of this code. When it is triggered, the sensor activates a mode of measurement Mode_MES with fast acquisition of image data for k different values of exposure time Ti, i=1 to k, k at least equal to 2 and this acquisition serves only for the sensor and only to rapidly define a desirable value of exposure time on the basis of the histograms calculated H(Ti) on the image data acquired for the various exposure times; this value is stored in the register of picture capture parameters, and the sensor then activates a nominal image acquisition mode Mode_ACQ, which applies this desirable exposure time value provided by the register to all the pixels of the matrix, and the image obtained DATA-OUT is that delivered as output by the sensor, for code decoding/recognition by an external system.