Document Size Detection Using Multi-Phase Light Source Control
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Solution Overview
Problem
Existing document size detection methods in image reading devices are prone to errors due to foreign matters like scrap paper or fingerprints at the reading position, leading to inaccurate determination of document size.
Innovation Solution
A document size detection device that uses a light source and imaging device to acquire image data at multiple reading positions, including when the light source is switched on and off, and while moving, to accurately determine the document size by reducing the influence of foreign matters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If document size is determined based on data acquired when light source is stopped at a fixed reading position, then measurement speed is improved, but measurement precision deteriorates due to foreign matter interference
Solution Approach 1:
The patent divides the document size detection process into multiple measurement phases: a first measurement at a first reading position, a second measurement at a second reading position, and a third measurement while moving the light source. By segmenting the measurement process across different positions and states, the system can identify and eliminate measurements affected by foreign matter, thereby improving accuracy while maintaining efficiency.
Solution Approach 2:
The patent performs preliminary measurements at multiple reading positions before final document size determination. These preliminary actions include measuring at stationary positions with light source on and off, and while moving, to establish a baseline of measurements from which foreign matter interference can be identified and removed before the final size calculation.
2Measurement precision
If multiple reading positions and light source states are used for measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the light source serve multiple functions: it is used both for illumination during measurement and as a reference for detecting foreign matter by comparing measurements with light on and off. The same imaging device captures images in all measurement phases. This multi-functionality reduces the need for additional specialized components, thereby limiting the increase in device complexity while achieving higher measurement precision.
Solution Approach 2:
The patent combines multiple measurement functions into a unified detection process. The imaging device simultaneously performs document size measurement and foreign matter detection by analyzing images captured during different light source states and movement conditions. This merging of functions into a single integrated process reduces overall system complexity compared to using separate dedicated systems for each function.
3Measurement precision
If data from multiple reading positions is collected and processed, then measurement precision is improved, but loss of time increases due to additional data acquisition
Solution Approach 1:
The patent performs measurements continuously in different phases without significant interruptions. The light source is switched on and off, and the reading position is changed, while the imaging device continuously captures images. This continuous acquisition of useful measurement data across different conditions allows for robust foreign matter identification and elimination without significant time loss, as the measurements are taken in a streamlined sequence rather than as separate discrete operations.
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
Improves the accuracy of document size detection by considering data from multiple positions, reducing the likelihood of erroneous size determination caused by foreign materials.
Implementation Method 1
a light source to irradiate a document with light; an imaging device to receive light reflected at the document
Data Source
AI summary
A document size detection device includes: a light source to irradiate a document with light; an imaging device to receive light reflected at the document; and circuitry to control switch on and off of the light source and movement in a sub-scanning direction of the light source, and determine a size of the document based on image data acquired by the imaging device. The circuitry is to determine a size in a main-scanning direction of the document based on: first image data acquired when the light source is switched off while the light source is at a first reading position; second image data acquired when the light source is switched on while the light source is at the first reading position; and third image data acquired when the light source is switched on while the light source is being moved from the first reading position to a second reading position.