Image Reader Document End Detection via Light Guide
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Solution Overview
Problem
Existing image readers require a separate document detecting sensor to identify the leading and trailing ends of a document sheet, increasing manufacturing costs.
Innovation Solution
An image reader configuration that uses a light guide to direct light from a first image sensor to a second image sensor, allowing the controller to detect the document ends based on changes in the light receiving state, eliminating the need for a separate detecting sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate document detecting sensor is used to detect the leading end and trailing end of the document sheet, then the detection accuracy is improved, but the manufacturing cost increases
Solution Approach 1:
The image sensors are made to perform dual functions: capturing image data from document sides and detecting the leading end/trailing end of the document sheet. By using the same hardware components for multiple purposes, the patent eliminates the need for separate document detecting sensors, thereby reducing manufacturing costs while maintaining detection capability
Solution Approach 2:
The patent combines the document end detection function with the image sensing function by integrating the detection capability into the existing image sensors. The light receiving portions of the image sensors are used to detect both reflected light from the document and the presence of document edges, merging two functions into a single system
2Reliability
If a separate document detecting sensor is used, then the document end detection reliability is improved, but the device complexity increases
Solution Approach 1:
The image sensors perform multiple functions including image capture and document end detection, reducing the total number of sensors needed and simplifying the overall system architecture while maintaining reliable detection through the dual-purpose design
Solution Approach 2:
The image sensors utilize their own light receiving capabilities to detect document ends without requiring external dedicated sensors. The system serves itself by using the existing image sensing infrastructure for both imaging and detection purposes, thereby reducing system complexity
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 configuration simplifies the manufacturing process by integrating end detection within the image sensors, reducing costs and enabling efficient detection of document ends without additional sensors.
Implementation Method 1
a light guide unit that forms an optical path to guide the light emitted by the first light emitting portion to the second light receiving portion
Implementation Method 2
the document sheet passing through the detection position on the feeding path blocks the light that is guided on the optical path from the first light emitting portion to the second light receiving portion
Implementation Method 3
a first light emitting portion configured to emit light onto a first side of a document sheet
Implementation Method 4
a first light receiving portion configured to receive the light reflected from the first side of the document sheet
Implementation Method 5
a second light emitting portion configured to emit light onto a second side opposite to the first side of the document sheet
Implementation Method 6
a second light receiving portion configured to receive the light reflected from the second side of the document sheet
Data Source
AI summary
An image reader is provided, which includes a light guide unit forming an optical path to guide light emitted by a first light emitting portion of a first reading unit to a second light receiving portion of a second reading unit, which optical path passes across a feeding path in a detection position such that a document sheet passing through the detection position on the feeding path blocks the light on the optical path, and a controller determining that a leading end or a trailing end of the document sheet passes through the detection position in response to detecting a change in a light receiving state of the second light receiving portion when the document sheet passes through the detection position with the first light emitting portion emitting light and a second light emitting portion of the second reading unit not emitting light.