Sensor Shutter with Protruding Wall for Toner Detection
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Solution Overview
Problem
In image forming apparatuses, foreign objects such as toner and paper dust can adhere to the detection surface of sensors, leading to decreased detection accuracy, especially when a protection member moves, causing foreign objects to drop onto the sensor due to changes in acceleration or impact.
Innovation Solution
A shutter with a detection hole and a cover portion is positioned between the sensor and the rotational member, allowing detection of toner images while preventing foreign objects from dropping onto the sensor by using a protruding wall portion at the upstream edge of the detection hole to deflect them away from the sensor surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection member is moved to expose the detection surface of the sensor, then foreign objects adhering to the protection member may drop onto the detection surface due to changes in acceleration or impact, but the detection surface needs to be exposed for sensor operation
Solution Approach 1:
A shutter is introduced as an intermediary component between the protection member and the sensor. The shutter includes a detection hole that can be positioned to either expose or cover the sensor's detection surface. This intermediary structure allows controlled exposure of the sensor while the protruding wall portion prevents foreign objects from the protection member from reaching the sensor, thus resolving the contradiction between needing to expose the sensor and preventing contamination.
Solution Approach 2:
The solution adds a spatial dimension by introducing a protruding wall portion that extends in the widthwise direction (perpendicular to the movement direction of the protection member). This three-dimensional structure creates a physical barrier that prevents foreign objects from traveling in a straight line from the protection member to the sensor, effectively blocking the contamination path while allowing the sensor to function when the detection hole is positioned appropriately.
2Object-affected harmful factors
If the detection surface of the sensor is covered by a protection member, then foreign objects are prevented from adhering to the sensor, but the sensor cannot detect the toner image
Solution Approach 1:
The shutter is designed to be movable in the widthwise direction, allowing it to dynamically switch between two states: covering the sensor to prevent foreign object contamination, and exposing the sensor through the detection hole to enable toner image detection. This dynamic positioning resolves the contradiction by allowing the system to adapt its configuration based on whether protection or detection is the priority at any given moment.
Data Source
AI summary
There is provided a configuration in which a foreign object is less likely to drop onto a detection surface of a sensor when a protection member moves. The protection member is disposed above the sensor movably between a first position and a second position, and has a detection hole formed to expose a detection surface of the sensor at the first position. The protection member covers the detection surface in a part, in which the detection hole is not formed, at the second position. A protruding wall portion is provided at least at an upstream edge of the detection hole, with respect to a direction in which the protection member moves from the second position to the first position, so as to protrude upward from a top surface of the protection member.