Document Size Detection via Pre-Scan Light Intensity
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Solution Overview
Problem
Current document scanning devices lack an efficient method to automatically determine the size and position of a document on a platen, which is crucial for accurate scanning and reproduction.
Innovation Solution
A system utilizing a transparent platen with a light source, such as LEDs, and a scan head with optical sensors that pre-scan the document by sensing light intensities from areas covered and uncovered by the document, allowing for the determination of its border and location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional scanning methods are used without pre-scan detection, then the scanning process is simpler, but the ability to automatically determine document size and position is lost
Solution Approach 1:
The system performs a pre-scan operation before the actual scanning to detect document boundaries and position. The pre-scan uses the same optical sensors to gather information about document placement, enabling automatic size and position determination without manual intervention.
Solution Approach 2:
The patent introduces a light source system that illuminates the platen from below, creating optical conditions that enhance the contrast between document areas and empty platen areas. This intermediary lighting system enables the optical sensors to detect document boundaries more effectively.
2Measurement precision
If a pre-scan is performed to detect document boundaries, then measurement accuracy improves, but scanning time increases
Solution Approach 1:
The pre-scan operation scans only the areas necessary to detect document boundaries and position, rather than performing a complete high-resolution scan. This partial scanning approach provides sufficient information for boundary detection while minimizing the time penalty.
3Illumination intensity
If multiple light sources are used to illuminate the platen, then document visibility improves, but energy consumption increases
Solution Approach 1:
The light sources are activated only during the pre-scan operation to detect document boundaries, and then deactivated before the main scanning process. This periodic activation ensures adequate illumination when needed while minimizing overall energy consumption during the scanning cycle.
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 accurate determination of document size and position, facilitating precise scanning and reproduction by distinguishing between light intensities from covered and uncovered areas, thereby improving scanning efficiency and accuracy.
Implementation Method 1
the present system utilizes a plurality of light emitting diodes (LEDs) positioned such that a topside of the platen is illuminated thereby
Implementation Method 2
During the pre-scan, optical sensors of the scan head sense light from the LEDs of areas of the platen not covered by the hardcopy print at a first intensity and sense light from the LEDs of areas that are covered by the hardcopy print at a second intensity
Data Source
AI summary
What is disclosed is a system for determining the size of a document on a platen of a document scanning device. In one embodiment, the scanning device comprises in part: a transparent pane (platen) whereon a hardcopy print is placed; a scan head comprising optical sensors which output a signal comprising an image of that hardcopy print; a plurality of LEDs positioned such that a topside of the platen is illuminated; and a processor for instructing the scan head to pre-scan the print. During the pre-scan, optical sensors comprising the scan head sense light from the LEDs of areas of the platen not covered by the hardcopy print at a first intensity and sense light from the LEDs of areas of the platen which are covered by the print at a second intensity. The processor determines the size of the hardcopy print from the first and second intensity levels.