Document Size Detection Device Illumination Depth Control
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Solution Overview
Problem
Existing document size detection methods in image reading devices face challenges in accurately detecting high-density documents, as they either suffer from low detection accuracy due to simple configurations or require multiple sensors for improved accuracy.
Innovation Solution
A document size detection device that uses a light source to irradiate a document with scanning light, with a switching mechanism to control illumination depth, allowing for size detection based on the difference between image data acquired with and without the scanning light, thereby improving detection accuracy for high-density documents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pre-scanning is performed only once at a predetermined time before main scanning (normal method), then the size detection processing can be performed by a simple configuration, but detection accuracy for high-density documents cannot be improved
Solution Approach 1:
The patent performs pre-scanning at multiple predetermined times (before background plate closure and after background plate closure) to capture document information in advance. This preliminary action at multiple stages enables accurate detection of high-density documents without requiring complex real-time processing during main scanning.
Solution Approach 2:
The detection process is segmented into multiple pre-scanning phases: first pre-scanning before background plate closure and second pre-scanning after closure. Each phase captures different document characteristics, and combining these segmented detection results achieves high accuracy for high-density documents while maintaining overall system simplicity.
2Measurement precision
If pre-scanning is performed twice at two different points of time before main scanning (two-stage method), then detection accuracy for high-density documents can be improved, but a plurality of sensors that detect background plate angle are necessary
Solution Approach 1:
The patent uses a single sensor to perform multiple functions: detecting both the first background plate angle (before closure) and the second background plate angle (after closure) for pre-scanning operations. This multi-functional use of one sensor achieves two-stage detection accuracy without requiring multiple dedicated sensors.
Solution Approach 2:
The system changes the operational parameters of the single sensor by detecting background plate angles at different time points (before and after closure). By varying the temporal parameter of detection rather than adding spatial redundancy with multiple sensors, the system achieves improved detection accuracy with minimal hardware.
3Device complexity
If background light is not eliminated during size detection, then the detection process is simple, but detection accuracy for high-density documents deteriorates due to disturbance light influence
Solution Approach 1:
The patent performs preliminary detection of disturbance light characteristics during pre-scanning phases before main scanning. By characterizing and accounting for disturbance light in advance through multiple pre-scanning operations, the system can accurately detect high-density documents without requiring complex real-time background elimination during critical detection.
Solution Approach 2:
The system uses feedback from pre-scanning operations to adjust and improve main scanning detection. Information obtained from first and second pre-scanning (including disturbance light characteristics) feeds into the main scanning process, enabling accurate size detection of high-density documents while maintaining process simplicity.
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
The solution enhances detection accuracy for high-density documents by eliminating the influence of disturbance light and improving the illumination depth characteristics, allowing for precise size determination.
Implementation Method 1
illuminating means that irradiates the document with scanning light via the placing means... reading means that receives reflection light from the document via the placing means to acquire image data of the document
Implementation Method 2
illumination depth controlling means that controls an illumination depth of the scanning light; The illumination depth controlling means sets an illumination depth of the scanning light at a size detection time when the size is detected, shallower than an illumination depth of the scanning light at an image reading time
Data Source
AI summary
A document size detection device includes: a light source that irradiates a document placed on placing means with scanning light via the placing means; a reading unit that receives reflection light from the document via the placing means to acquire image data of the document; and circuitry to set an illumination depth of the scanning light at a size detection time when the size is detected, shallower than an illumination depth of the scanning light at an image reading time when an image of the document is read, and detects, at the size detection time, the size based on a difference between first image data acquired in a state in which the scanning light is switched off and second image data acquired in a state in which the scanning light is switched on.