Edge Position Detection Using Multi-Wavelength Pixel Array
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately reading the edge position of sheets, particularly due to variations in sheet color and surface states, which can lead to misalignment and erroneous detection.
Innovation Solution
The implementation of a reading device that emits near-white light and uses a pixel array to detect red, green, and blue light reflections, allowing for accurate edge position detection by summing output values across multiple colors to enhance signal quality and reduce noise from dirt or background reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single wavelength light source is used for edge detection, then the device structure is simple, but detection accuracy deteriorates due to variations in sheet color and surface states
Solution Approach 1:
The patent segments the light detection function into multiple wavelength components by using a pixel array that can detect red, green, and blue light separately. This allows the system to process different wavelength reflections independently and combine them for accurate edge detection, resolving the contradiction between simple structure and high precision.
Solution Approach 2:
The pixel array is designed to perform multiple functions: detecting edge positions, determining sheet color, and assessing surface states. By integrating these functions into a single detection device, the patent achieves high detection accuracy without proportionally increasing device complexity.
2Measurement precision
If multiple light sources with different wavelengths are used sequentially, then detection accuracy improves, but the operation time increases
Solution Approach 1:
The patent merges multiple wavelength detection capabilities into a single pixel array that can detect red, green, and blue light simultaneously. This eliminates the need for sequential switching of light sources while maintaining the ability to analyze different wavelength reflections, thus improving detection speed without sacrificing accuracy.
Solution Approach 2:
The detection system operates continuously by capturing reflected light across multiple wavelengths in a single measurement cycle. This continuous detection approach eliminates idle time between sequential measurements while maintaining comprehensive color and edge information.
3Productivity
If edge detection is performed without considering sheet color, then the detection process is fast, but accuracy deteriorates due to color variations affecting reflection characteristics
Solution Approach 1:
The system performs preliminary analysis of sheet color and surface state by examining the reflection characteristics across red, green, and blue wavelength bands. This preliminary information is then used to optimize the edge detection process, allowing fast and accurate detection by adapting to each sheet's specific properties.
Solution Approach 2:
The detection algorithm dynamically adjusts parameters based on the measured sheet color and surface state. By changing detection thresholds and processing methods according to the specific sheet properties identified through multi-wavelength analysis, the system maintains high speed and accuracy across diverse sheet types.
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 enables precise edge position reading regardless of sheet color or surface type, minimizing misalignment and erroneous detections, and improves the accuracy of image formation by correctly identifying the sheet edge.
Implementation Method 1
detects an end position of a sheet in a width direction using reflected light, from the sheet, of light appropriate for the color of the sheet
Implementation Method 2
a pixel array in which a plurality of pixels that output detection signals are arranged
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A reading device (100) is configured to detect an edge position of a target object to be conveyed in a conveyance direction. The edge position is a position of an edge of the object in a width direction intersecting the conveyance direction. The reading device includes a sensor device (210), an adder (306), and an edge position detector (307). The sensor device includes a pixel array (212r, 212g, 212b) including a plurality of elements arranged in the width direction. The adder (306) adds detection signals output from the elements at respective positions in the width direction. The edge position detector is configured to detect the edge position on basis of a position at which an output of the adder changes to a value larger than a threshold. Each element is configured to output a detection signal based on a reception amount of light in one of different wavelength bands.