CIS Scan Bar Calibration for Variable LED Timing
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Solution Overview
Problem
Existing contact image sensor (CIS) scan bars have inefficiencies in timing synchronization, leading to wasted time and variable signal strength across different color LEDs, which affects scan quality and resolution.
Innovation Solution
A method is introduced to calibrate the CIS scan bar system by adjusting the timing of frame pulses and LED illumination durations to optimize the color scan line cycle, allowing for variable LED output without changing the aggregate integration time, thereby enhancing scan quality and reducing waste time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed timing is used for LED illumination in CIS scan bar, then device complexity is reduced, but scan quality deteriorates due to variable signal strength across colors
Solution Approach 1:
The patent applies parameter changes by adjusting the illumination duration of each LED color (red, green, blue) individually to compensate for variations in LED output intensity. The system modifies the time parameter for each color channel to achieve balanced signal strength across all colors, thereby improving scan quality without requiring hardware modifications.
Solution Approach 2:
The patent implements feedback through an automated calibration process that measures the actual output signal strength from each LED color and uses this information to adjust the illumination timing parameters. The system performs measurements during calibration and feeds this data back to optimize the scan quality, eliminating the need for manual timing adjustments.
2Productivity
If equal time is allocated to each color LED, then device complexity is minimized, but productivity decreases due to wasted time when LEDs are off
Solution Approach 1:
The patent applies dynamics by transitioning from fixed, equal time allocation for each color LED to dynamic, variable illumination durations. The system adaptively adjusts the on-time for each LED based on its actual output characteristics, allowing the scan bar to optimize the color scan line cycle time and reduce wasted idle time, thereby improving overall productivity.
Solution Approach 2:
The system changes the time parameter for each color channel individually, allowing shorter illumination times for LEDs with higher output and longer times for LEDs with lower output. This parameter optimization eliminates the need to allocate equal time to all colors, reducing the total cycle time and improving scan speed.
3Measurement precision
If longer illumination time is used for each LED, then measurement precision improves, but loss of time increases due to extended color scan line cycle
Solution Approach 1:
The patent optimizes the illumination time parameter for each LED color individually, finding the minimum effective duration needed to achieve sufficient signal strength. By adjusting each color's timing parameter based on its specific output characteristics, the system avoids using unnecessarily long illumination times for all colors, thereby reducing the total color scan line cycle time while maintaining measurement precision.
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 results in improved scan quality by optimizing the use of time and balancing signal strength across colors, leading to better image capture efficiency and potentially shorter scan line cycles.
Implementation Method 1
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Data Source
AI summary
A method of calibrating a document scanner contact image sensor scan bar having an LED array to increase LED sensor array output and/or reduce total color scan line cycle time.