Belt Unit Switch Mechanism for Image Forming Apparatus

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Solution Overview

Problem

In electro-photographic image forming apparatuses, the lack of a mechanism to prevent image formation when the belt unit is not attached to the body can lead to paper jams and operational failures, as the recording material cannot be properly conveyed without the belt unit.

Innovation Solution

An image forming apparatus with a switch mechanism and a switching member on the opening and closing member that prevents image formation when the belt unit is not attached, ensuring the opening and closing member cannot be fully closed, thereby preventing the switch from being activated and allowing the belt unit to be safely detached or attached.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of repair

If the belt unit is made detachable for maintenance, then ease of repair is improved, but reliability deteriorates due to risk of paper jam when belt is not attached

Engineering Contradiction:
Improveease of repairVSAvoidreliability
Core Design Contradiction:
Ease of repairVSReliability

Solution Approach 1:

The switch is positioned and configured in advance so that it is automatically actuated when the belt unit is removed, before any image formation operation can occur. This preliminary positioning ensures that the prohibition function is activated proactively, preventing paper jam before it can happen.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The switch acts as an intermediary between the belt unit attachment state and the image formation operation. It translates the physical state of belt attachment into an electrical signal that controls the operation enablement, creating a safety intermediary that prevents harmful operations when the belt is missing.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a switch mechanism is added to prohibit operation, then reliability is improved, but device complexity increases

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The switch serves multiple functions: it detects belt unit attachment status, controls operation enablement, and provides user feedback through the display. By making the switch multi-functional, the patent reduces the need for separate components for each function, thereby limiting the increase in device complexity while maintaining improved reliability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the natural closing action of the door assembly itself to actuate the switch. The door's closing motion automatically triggers the switch without requiring separate actuators or complex mechanisms, allowing the structure to serve its own function of enabling/disabling operation based on its position.

Inventive Principle:
Principle #25Self-service

3Ease of operation

If the door assembly is used to detect belt attachment, then ease of operation is improved, but device complexity increases

Engineering Contradiction:
Improveease of operationVSAvoiddevice complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The door assembly serves dual purposes: it provides physical access control (opening/closing the door) and simultaneously acts as a mechanical switch actuator to detect belt unit attachment. This multi-functionality allows the patent to use an existing structural component for detection, avoiding the need for separate sensors or complex detection mechanisms.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentUS9377748B2Image forming apparatus
Publication Date: 2016.06.28 CANON KK

AI summary

In a case where a belt unit is not attached to an apparatus body, when an opening and closing member is closed against the apparatus body, a switching member cannot press a switch, and image formation operation is prohibited. In a case where the belt unit is attached to the apparatus body, when the opening and closing member is closed against the apparatus body, the switching member presses the switch, and the prohibition of the image formation is released.