Document Placement Detection Using Invisible Light
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Solution Overview
Problem
Existing image reading devices delay the start of operations like copying or scanning due to the need for the pressure plate to be completely closed before detecting document size, which increases the time required for document placement detection.
Innovation Solution
A document placement detecting device that uses invisible light sources to continuously monitor image data from a transparent document table, allowing for real-time detection of document placement and size without requiring the pressure plate to be fully closed, and includes visible light sources for regular reading operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pressure plate is completely closed before detecting document size, then the document size can be accurately detected, but the start of copying or scanning operations is delayed
Solution Approach 1:
The patent applies preliminary action by detecting document placement and size using invisible light sources before the pressure plate is completely closed. The imaging device captures images of the document placement area using invisible light irradiation during the closing process of the pressure plate, enabling early detection without waiting for the plate to fully close. This resolves the contradiction by performing the detection action in advance, thereby reducing the time loss while maintaining detection accuracy.
Solution Approach 2:
The patent uses invisible light sources as an intermediary to enable document detection during the pressure plate closing process. Instead of requiring the pressure plate to be fully closed for detection, the invisible light sources illuminate the document placement area through the transparent or translucent pressure plate, allowing the imaging device to capture images at any stage of closing. This intermediary approach enables accurate detection without the time delay caused by waiting for complete plate closure.
2Measurement precision
If visible light sources are used for document reading, then the document can be read clearly, but glare issues occur during document placement
Solution Approach 1:
The patent segments the lighting function into two separate systems: invisible light sources for document placement detection and visible light sources for document reading. The invisible light sources (e.g., infrared LEDs) are used specifically for detecting document placement and size without causing glare, while the visible light sources are activated only after placement detection is complete for clear document reading. This segmentation resolves the contradiction by assigning different lighting functions to different light sources, eliminating glare during placement while maintaining reading clarity.
Solution Approach 2:
The patent applies local quality by using different types of light sources for different functional requirements. Invisible light sources are localized for placement detection in the document placement area, while visible light sources are used for reading operations. This differentiation of light source properties according to functional needs allows the system to avoid glare during placement (using invisible light) while ensuring clear visibility during reading (using visible light).
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
Enables immediate start of copying or scanning operations by detecting document placement and size in real-time, reducing power consumption and eliminating glare issues during document placement, while also reducing the time needed for size detection and improving user convenience.
Implementation Method 1
The imaging device receives reflected light from the document, and outputs read data
Data Source
AI summary
A document placement detecting device includes a document table, a plate, a plurality of invisible light sources, an imaging device, and circuitry. The document table transmits light. The plate is openable and closable relative to the document table, and covers the document table in a closed state of the plate. The plurality of invisible light sources irradiate a placement area with invisible light via the document table. The placement area is an area of the document table on which a document is placed. The imaging device receives reflected light from the document, and outputs read data. The circuitry detects the placement of the document with a change in a read value of the read data output from the imaging device based on the irradiation with the invisible light.