Image Reader Light Timing Control for Moire Fringe Reduction
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Solution Overview
Problem
Image readers that supply the same level of driving current to multiple light sources emitting different-color light beams face issues with reading thin lines and Moire fringes due to non-light-emitting periods, where none of the light sources emit light, leading to incomplete image capture.
Innovation Solution
An image reader configuration that includes a light-emitting-time determining unit to set separate light-emitting times for each light source and divides non-light-emitting periods into segments, dispersing them within the reading period to ensure continuous light emission, preventing gaps in image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same level of driving current is supplied to each light source, then the configuration is simplified, but non-light-emitting periods occur causing incomplete image capture
Solution Approach 1:
The patent applies periodic action by sequentially controlling multiple light sources to emit light in alternating periods. Each light source emits light during its designated time window, ensuring continuous light emission across the entire reading period. This periodic activation pattern eliminates non-light-emitting periods while maintaining the simplified single-unit current supply configuration.
Solution Approach 2:
The patent implements preliminary action by pre-calculating and setting the light-emitting time for each light source based on its characteristics. The light-emitting time is determined in advance to ensure that the sum of all light-emitting periods equals the total reading period, thereby preventing non-light-emitting periods before the actual reading process begins.
2Illumination intensity
If light-emitting time is set separately for each light source, then light intensity requirements are met, but non-light-emitting periods occur during reading
Solution Approach 1:
The patent uses periodic action to organize light emission from multiple light sources in sequential time windows. Each light source is assigned a specific light-emitting period, and these periods are arranged to cover the entire reading duration without gaps. This ensures both adequate illumination intensity for each color channel and continuous light emission throughout the reading process.
Solution Approach 2:
The patent merges the light-emitting periods of multiple light sources into a unified continuous emission sequence. By combining the individual light-emitting times of red, green, and blue light sources and arranging them sequentially, the system achieves continuous light coverage while maintaining the specific illumination intensity requirements for each color.
3Adaptability or versatility
If non-light-emitting periods exist in the reading period, then light source characteristics are accommodated, but thin lines and Moire fringes cannot be read
Solution Approach 1:
The patent applies periodic action to eliminate non-light-emitting periods by organizing sequential light emission from multiple light sources. Each light source emits light during its assigned time window, ensuring that the entire reading period is covered with continuous light emission. This maintains adaptability to different light source characteristics while ensuring accurate reading of thin lines and prevention of Moire fringes.
Solution Approach 2:
The patent implements continuity of useful action by ensuring that light emission continues without interruption throughout the entire reading period. The light-emitting periods of different light sources are arranged sequentially to cover the full reading duration, eliminating gaps where no light is emitted. This continuous light emission ensures accurate image capture including thin lines and prevents Moire fringe formation.
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 prevents failures in reading thin lines and reduces Moire fringes by ensuring continuous light exposure during the reading process, enhancing the image reader's ability to capture images accurately.
Implementation Method 1
a plurality of light sources each of which is configured to emit light of a wavelength different from wavelengths of the other light sources
Implementation Method 2
a light introducing unit configured to introduce the light emitted by each light source so as to be incident onto the document sheet
Implementation Method 3
a light receiving unit comprising light receiving elements disposed linearly along a main scanning direction perpendicular to the auxiliary scanning direction, the light receiving unit being configured to receive light reflected from the document sheet and output a reading signal corresponding to a light intensity of the received light
Data Source
AI summary
An image reader is provided, which includes a light-emitting-timing setting unit configured to divide a non-light-emitting time during which none of light sources emits light in a predetermined reading period into a plurality of segmental non-light-emitting times and set a light-emitting moment separately for each light source as a moment to emit the light in the predetermined reading period, such that the segmental non-light-emitting times are arranged in a dispersed manner in the predetermined reading period, and a controller configured to control each light source to emit the light during a light-emitting time determined separately for each light source at the light-emitting moment set by the light-emitting-timing setting unit.