Document Conveying with Angled Optical Detection and Dynamic Tray Capacity
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Solution Overview
Problem
Existing document conveying devices face issues with false detection of documents due to light reflection from pickup rollers, which can occur when reflective optical sensors are positioned vertically upward, and there is a need to increase the capacity of the sheet feeding and discharge trays without increasing their size.
Innovation Solution
The document conveying device incorporates a reflective optical sensor that emits light in a direction inclined downstream from the vertical, a sheet feeding tray lifting mechanism, and a lifting wall part that is biased upward and can be lifted and lowered smoothly, allowing for increased capacity without increasing the device's size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the reflective optical sensor is disposed to emit light vertically upward, then the sensor can detect the document in contact with the lifting wall part, but false detection occurs due to light reflection by the pickup roller
Solution Approach 1:
The reflective optical sensor is disposed to emit light in an asymmetric direction (inclined downstream direction) rather than vertically upward, creating an asymmetric optical path that avoids reflection from the pickup roller while maintaining detection capability for documents in contact with the lifting wall part
2Quantity of substance
If the sheet feeding tray capacity is increased, then more documents can be stored, but the device size increases
Solution Approach 1:
The lifting wall part is made movable rather than fixed, allowing it to be lifted and lowered according to the number of documents in the sheet feeding tray. This dynamic adjustment enables the tray to accommodate varying document quantities without requiring a larger fixed structure, thereby increasing effective capacity without proportionally increasing device volume
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 reduces false document detection and enhances the capacity of the sheet feeding and discharge trays, ensuring stable and efficient document conveyance.
Implementation Method 1
If the reflective optical sensor is disposed to emit light vertically upward, there is a risk of false detection as the light is reflected by the pickup roller
Data Source
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AI summary
A document conveying device (120) includes a sheet feeding tray (44), a sheet feeding mechanism (31), a sheet feeding tray lifting mechanism (33), a top plate (21), a fixed wall part (23), a lifting wall part (25), and a reflective optical sensor 847). The top plate (21) is in contact with a lower surface of the document to be fed. The fixed wall part (23) is provided extending downward from an upstream side end portion of the top plate (21), and is fixed in position. The lifting wall part (25) is provided extending upward from a downstream side end portion of the sheet feeding tray (44), and lifted and lowered along the fixed wall part (23) together with the sheet feeding tray (44). The reflective optical sensor (47) detects the document placed on the sheet feeding tray (44). The reflective optical sensor (44) emits light in a direction inclined downstream of the sheet feeding direction from a vertically upward direction.