Sheet Feed Device with Movable Second Tray for Reliable Feeding
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Solution Overview
Problem
Existing sheet feed devices face challenges in increasing the capacity of the first tray without increasing the height of the sheet feed device, leading to potential sheet feeding failures due to decreased sheet drawing force and idle rotation of the feed roller.
Innovation Solution
A sheet feed device design that includes a first tray with a support for a second tray, where the second tray can be selectively positioned to optimize sheet feeding, maintaining a shorter distance between the trays in the sheet feed position to ensure reliable feeding without increasing the device's height, and utilizing a feed roller mechanism that adjusts its angle to maintain effective sheet drawing force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the height of the first tray is increased to increase its capacity, then the maximum number of sheets stored in the first tray increases, but the angle of the arm with respect to the upper surface of the sheets decreases, resulting in decreased sheet drawing force and potential sheet feeding failure
Solution Approach 1:
The invention changes the problem from a vertical dimension solution (increasing tray height) to a horizontal/depth dimension solution (increasing tray capacity through extended depth while maintaining height). The first tray is designed with increased capacity by extending in the sheet feed direction rather than increasing vertical height, thus avoiding the arm angle degradation issue while achieving higher sheet storage capacity.
Solution Approach 2:
The invention makes the second tray dynamically positionable along the sheet feed direction, allowing it to move between a retracted position (when feeding from first tray) and a sheet feed position (when feeding from second tray). This dynamic positioning enables the system to adapt to different feeding scenarios without requiring height increases that would compromise sheet drawing force.
2Reliability
If the mounting position of the feed unit is raised to prevent sheet feeding failure from the second tray, then sheet feeding reliability improves, but the height of the image recording apparatus increases
Solution Approach 1:
Instead of solving the sheet feeding reliability problem by increasing vertical height (mounting feed unit higher), the invention uses the horizontal dimension by positioning the second tray closer to the feed roller in the sheet feed direction. This reduces the distance the sheet must travel and maintains drawing force without increasing apparatus height.
Solution Approach 2:
The invention creates a functional copy of the feeding capability by providing two separate trays (first and second trays) that can both feed sheets to the same recording unit. The second tray is positioned to provide an alternative feeding path that maintains reliability without requiring vertical repositioning of the feed unit.
3Reliability
If the second tray is positioned closer to the feed roller in the sheet feed direction, then sheet drawing force is maintained and feeding reliability improves, but the device complexity increases due to the movable support mechanism
Solution Approach 1:
The second tray is designed with a movable support mechanism that allows it to dynamically position itself in the sheet feed direction. The tray can move between a retracted position (aligned with the rear surface of the first tray) and a sheet feed position (closer to the feed roller). This dynamic positioning enables the system to optimize sheet drawing force and feeding reliability without requiring permanent structural modifications or complex adjustable mechanisms.
Solution Approach 2:
The movable support mechanism serves multiple functions: it enables the second tray to feed sheets reliably when positioned close to the feed roller, and it allows the second tray to be retracted when feeding from the first tray. This single mechanism provides both positioning and functional versatility, reducing the need for separate mechanisms for each function.
Data Source
AI summary
A sheet feed device includes a first tray comprising a first plate configured to receive a first plurality of sheets thereon, in which the first tray includes a support, and a second tray positioned on the first tray. The second tray includes a first and a second side portion, and a second plate configured to receive a second plurality of sheets thereon. The device also includes a feed roller configured to selectively feed the sheets in a sheet feed direction. The support is configured to selectively support the second tray at a retracted position and a sheet feed position at which the feed roller is configured to selectively feed the first plurality of sheets and the second plurality of sheets, respectively. Moreover, a shortest distance between an upper surface of the first plate and a lower surface of the second plate when the second tray is in the sheet feed position is less than a shortest distance in the retracted position.