Sheet Discharging Tray Detection Mechanism

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Solution Overview

Problem

Existing sheet discharging apparatuses face challenges in accurately detecting sheet presence due to wire management issues and instability in detecting curled or displaced sheets when the detection mechanism is located in the apparatus body, and they require complex arrangements to prevent wire interference and user access.

Innovation Solution

A sheet discharging apparatus with a detection mechanism where a sheet presence detecting flag is disposed on the discharge tray, and a transmission type optical sensor is located in the processing apparatus body, allowing for stable detection without the need for wires connecting the discharge tray to the apparatus body, and the flag's design ensures accurate detection even when sheets are curled or displaced.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the detection mechanism including a paper presence detecting plate and a paper presence detecting sensor is disposed in the discharge tray, then the detection mechanism can detect sheet presence, but the wires connecting the sensor with the apparatus body become long and interfere with the lift operation of the discharge tray

Engineering Contradiction:
Improvesheet presence detectionVSAvoidwire arrangement
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the detection mechanism from the movable discharge tray and relocates it to the stationary apparatus body. Specifically, the paper presence detecting sensor is fixed to the apparatus body, and the detection plate is configured to rotate about a pivot point on the apparatus body rather than moving with the tray. This extraction eliminates the need for long wires connecting the sensor to the movable tray, thereby removing wire interference with the lift operation while preserving sheet presence detection capability.

Inventive Principle:
Principle #2Taking out (Extraction)

2Device complexity

If the detection mechanism is disposed in the apparatus body, then wire management is simplified, but it becomes difficult to stably detect the sheet if the sheet is curled or the sheet is displaced

Engineering Contradiction:
Improvewire arrangementVSAvoidsheet presence detection stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent employs a lever arm mechanism where the detection plate extends beyond the end of the discharge tray in a direction perpendicular to the tray's movement. This dimensional extension allows the detection plate to reach and contact curled or displaced sheets that would otherwise be undetectable by a sensor positioned only at the tray's end. The lever arm amplifies small displacements of curled sheets into detectable movements of the detection plate.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The detection plate is configured to rotate about a pivot point rather than being rigidly fixed. This rotational degree of freedom allows the detection plate to dynamically adapt to various sheet positions and orientations. When a curled or displaced sheet contacts the detection plate, it causes rotation about the pivot point, enabling reliable detection regardless of sheet condition.

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If the detection mechanism moves up and down with the discharge tray, then it can detect sheets on the tray, but arrangements for guiding wires and preventing user damage are required

Engineering Contradiction:
Improvesheet presence detectionVSAvoiduser access to wires
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the detection mechanism from the movable discharge tray and relocates it to the stationary apparatus body. The sensor is fixed to the apparatus body frame, and the detection plate rotates about a pivot point on the apparatus body. This extraction eliminates wires that would otherwise need to extend to the movable tray, removing the hazard of user contact with exposed wires while maintaining detection functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

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 production costs, simplifies design, and ensures accurate sheet presence detection without wire interference, allowing for reliable and stable operation of the discharge tray.

Implementation Method 1

a transmission type optical sensor located in the processing apparatus body

Methodology Applied
Scientific EffectLight transmission detection: Photoelectric Effect

Data Source

PatentEP3257797B1Sheet discharging apparatus, and corresponding image forming apparatus
Publication Date: 2024.07.03 CANON KK
  • EP3257797B1 patent drawingFigure 1
  • EP3257797B1 patent drawingFigure 2
  • EP3257797B1 patent drawingFigure 3

AI summary

The present disclosure provides an apparatus to support a sheet and configured to stably detect a presence of the sheet with a simple arrangement, and an image forming apparatus including such apparatus. A sheet discharging apparatus (251) includes an apparatus body (200B), a discharge member (204) provided in the apparatus body and configured to discharge a sheet, a movable tray (302) movable with respect to the apparatus body and including a sheet supporting surface (2a) configured to support the sheet discharged by the discharge member (204), a movable member (308) supported by the movable tray (302) and configured to move by being pressed by the sheet supported on the sheet supporting surface (2a), and a detecting portion (221) provided in the apparatus body and configured to detect a presence of the sheet supported on the sheet supporting surface (2a) in response to a position of the movable member (308).