Contact Image Scanner Color Registration via Simultaneous Sensor Rows
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Solution Overview
Problem
Current imaging systems, particularly contact image scan bars, suffer from color misregistration issues known as color fringing, especially when scanning high spatial frequency content, and increasing scan speed exacerbates this defect, while trilinear scanners are costly and inefficient due to the need for multiple rows of sensors and complex circuitry.
Innovation Solution
The implementation of a light source, a plurality of pixel sensors, a lens, a color matrix filter, and a digital circuit to process signals from the sensors, allowing for sequential illumination and filtering of light along the document's length dimension, reducing color misregistration by minimizing overlap between color pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the scan bar moves faster to increase scanning speed, then productivity is improved, but color misregistration becomes more pronounced
Solution Approach 1:
The patent segments the color sensing function across three separate sensor rows (red, green, blue), each capturing color information simultaneously at the same spatial position. This segmentation allows independent optimization of each color channel's timing and positioning, eliminating the cumulative misregistration that occurs in sequential scanning methods when speed increases.
Solution Approach 2:
The patent transitions from sequential color scanning (time dimension) to simultaneous color sensing (spatial dimension). By arranging three sensor rows side-by-side in the vertical dimension, the system captures all color information at once for each horizontal position, removing the time-based misregistration that worsens with increased scanning speed.
2Manufacturing precision
If three rows of sensors are used to reduce color fringing, then color registration accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes each sensor row universal by using identical sensor structures for all three color channels. The same photodetector design, readout circuitry, and processing architecture are used for red, green, and blue sensors, simplifying manufacturing and reducing complexity compared to specialized sensors for each color.
Solution Approach 2:
The patent changes the parameter of sensor arrangement from sequential (one row scanning multiple colors over time) to parallel (three rows sensing simultaneously). This parameter change in spatial configuration reduces the need for complex timing control and data synchronization, thereby reducing device complexity while maintaining high color registration accuracy.
3Manufacturing precision
If three rows of sensors are used to reduce color fringing, then color registration accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the three color sensing functions into a single integrated sensor array module. By combining the red, green, and blue sensor rows into one unified structure with shared support infrastructure (housing, wiring, processing), the patent achieves cost efficiencies that offset the increased sensor count, making the high-precision system more manufacturable than separate sequential scanning systems.
4Device complexity
If sequential color exposures are used to simplify the sensor design, then device complexity is reduced, but color misregistration occurs
Solution Approach 1:
The patent segments the color sensing function across three separate sensor rows (red, green, blue), each capturing color information simultaneously at the same spatial position. This segmentation allows independent optimization of each color channel's timing and positioning, eliminating the cumulative misregistration that occurs in sequential scanning methods when speed increases.
Solution Approach 2:
The patent transitions from sequential color scanning (time dimension) to simultaneous color sensing (spatial dimension). By arranging three sensor rows side-by-side in the vertical dimension, the system captures all color information at once for each horizontal position, removing the time-based misregistration that worsens with increased scanning speed.
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 effectively minimizes color misregistration artifacts, maintains image quality at higher scan speeds, and reduces costs by eliminating the need for multiple sensor rows and complex analog front ends, resulting in a more efficient and cost-effective scanning process.
Implementation Method 1
a lens for focusing light from the light source reflected from the document onto the plurality of pixel sensors
Implementation Method 2
a color matrix filter disposed between the pixel sensors and the light reflected from the document
Implementation Method 3
a plurality of pixel sensors for generating a signal in response to light incident thereon
Data Source
AI summary
A contact image scanner comprises a light source, pixel sensors generating a signal, a lens focusing reflected light onto the pixel sensors, a color matrix filter filtering the reflected light, and a signal processing circuit generating a digital image. The method provides pixel sensors for generating a signal in response to incident light, projects light from a light source onto a document in a sequential fashion, reflects the light onto the pixel sensors, filters the reflected light with a color matrix filter, and processes the signal to generate the digital image. With the method and apparatus, each scan line of the document is illuminated with white light only once. The pixel sensors corresponding to red, green, and blue colors of each pixel of the scan line read the pixel of the scan line substantially at the same time in a substantially overlapping manner in a scan line direction without overlapping in an orthogonal direction.