Modulated LED Light Source for Continuous Image Scanner Scanning
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Solution Overview
Problem
Traditional image scanners require constant scanning rates to ensure proper exposure, leading to issues when memory buffers or image processors fail to keep up, resulting in overexposure or underexposure due to mechanical complexities in automatic document feeders (ADFs).
Innovation Solution
A modulated light source, such as an array of LEDs, dynamically adjusts its duty cycle based on document velocity to maintain constant exposure for each scan-line, eliminating the need for start-stop cycles and allowing continuous scanning at varying speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a constant scanning rate is used to ensure proper exposure, then exposure uniformity is improved, but productivity deteriorates when memory buffers or image processors fail to keep up
Solution Approach 1:
The light source intensity is dynamically adjusted based on the actual scanning rate. Instead of maintaining a fixed scanning rate, the system varies the light intensity in real-time to compensate for changes in document velocity, allowing the scanner to operate at higher productivity while maintaining exposure uniformity through active control.
Solution Approach 2:
The system changes the light source intensity parameter in response to changes in scanning rate. When the scanning rate increases or decreases, the light intensity is adjusted proportionally to maintain constant exposure, decoupling the scanning rate from exposure control and enabling flexible throughput management.
2Productivity
If the scanning rate is increased to improve productivity, then scan-line throughput is improved, but exposure uniformity deteriorates due to overexposure or underexposure
Solution Approach 1:
The system uses feedback from the scanning rate (or document velocity) to control the light source intensity. The controller monitors the actual scanning rate and adjusts the light intensity accordingly, creating a closed-loop control system that maintains exposure uniformity regardless of variations in productivity.
Solution Approach 2:
The light source intensity is made dynamic rather than static, allowing it to adapt to changing scanning rates in real-time. This dynamic adjustment enables the system to operate at varying productivity levels while maintaining consistent exposure quality.
3Productivity
If start-stop cycles are implemented to handle memory buffer limitations, then productivity is maintained, but device complexity increases due to mechanical retraction and acceleration requirements
Solution Approach 1:
The system replaces complex mechanical start-stop control with optical control of the light source. Instead of mechanically retracting and accelerating the scan bar or document, the system simply adjusts the light intensity to match the continuous scanning rate, eliminating the need for complex mechanical synchronization while maintaining productivity.
Solution Approach 2:
The invention extracts the exposure control function from the mechanical motion control system. By separating exposure control (light intensity) from motion control (scanning rate), the system eliminates the need for complex mechanical coordination required by start-stop cycles, simplifying the overall device architecture.
4Device complexity
If a constant light source intensity is used to simplify the system, then device complexity is reduced, but adaptability deteriorates when scanning rates must be changed
Solution Approach 1:
The light source intensity is made dynamically adjustable rather than fixed, allowing the system to adapt to different scanning rates. This dynamic capability provides versatility in scanning operations without significantly increasing device complexity, as the control mechanism integrates seamlessly with the existing scanning system.
Solution Approach 2:
The system enables easy adjustment of the light intensity parameter to match different scanning rates. This parameter adjustability provides adaptability for various scanning conditions while maintaining a relatively simple device structure, as the control system can be implemented through straightforward intensity modulation.
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 solution ensures uniform exposure regardless of document velocity, enabling continuous scanning without mechanical complexities, even during memory shortages or overloaded downstream processing.
Implementation Method 1
A modulated light source, such as an array of LEDs
Implementation Method 2
a linear array of image sensors (a scan bar) configured to scan an image line by line
Data Source
AI summary
This disclosure provides systems and methods for decoupling the mechanical drive systems of image scanners from the exposure system. A light source, such as an array of light-emitting diodes (LEDs), may be modulated in order to maintain a constant exposure for each scan-line, regardless of the document velocity. Accordingly, the present systems and methods allow for continuous document scanning at varying speeds. An automatic document feeder may dynamically adjust the velocity of a document without negatively impacting the exposure of the image scan. As the velocity of the document is changed, the modulation rate of the light source may be adjusted to maintain a constant exposure.