Developing Apparatus with U-Shaped Chamber and Variable Stirring
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Solution Overview
Problem
Existing developing apparatuses face issues with defective image formation and reduced toner concentration accuracy due to unstable developer discharge and imbalance in developer amount during changes in process speed, leading to image unevenness and excessive developer consumption.
Innovation Solution
A developing apparatus with a partitioned developer container featuring a first and second convey chamber, a first stir member, and a second stir member with a restriction portion to stabilize developer discharge, along with a U-shaped second convey chamber and a sensor disposition portion to enhance toner concentration detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the process speed is lowered to improve fixing performance and image quality for thick recording media, then fixing performance and image quality are improved, but the convey speed of the developer becomes low and the developer amount in the developing apparatus dramatically changes, causing image concentration to decrease and image unevenness to occur
Solution Approach 1:
The patent applies dynamics by making the stir member's rotational speed variable rather than fixed. The control unit adjusts the rotational speed of the stir member in response to changes in process speed, enabling the developing apparatus to adapt to different operating conditions. When process speed is lowered for thick media, the stir member speed is also reduced proportionally, preventing excessive developer amount changes and maintaining image quality across varying productivity requirements
Solution Approach 2:
The patent changes the parameter of stir member rotational speed based on process speed requirements. By dynamically adjusting this parameter, the system maintains optimal developer circulation and distribution regardless of whether operating at high speed for productivity or low speed for image quality, thus resolving the contradiction between manufacturing precision and productivity
2Productivity
If the stir member rotates at high speed to maintain developer circulation during fast process speed, then developer circulation is maintained, but when process speed is decelerated, the speed difference becomes large causing excessive developer discharge and image unevenness
Solution Approach 1:
The patent dynamically changes the rotational speed parameter of the stir member to match the process speed. When process speed decreases, the stir member speed is proportionally reduced, maintaining a consistent speed relationship that prevents excessive developer discharge and maintains stable developer amount even during deceleration from high to low speed operation
Solution Approach 2:
The control unit implements feedback by monitoring process speed changes and automatically adjusting the stir member's rotational speed accordingly. This closed-loop control ensures that the speed difference between stir member rotation and process speed remains within acceptable ranges, preventing image unevenness and maintaining stable developer circulation across varying productivity conditions
3Measurement precision
If a toner concentration sensor is disposed on the bottom portion of the housing to measure toner concentration, then toner concentration can be measured, but the developer surface may not be sufficient at the sensor position, reducing measurement accuracy
Solution Approach 1:
The patent transitions the sensor disposition from a bottom-positioned configuration to a side-positioned configuration on the convey chamber wall. This dimensional change allows the sensor to be placed in a location where developer naturally accumulates during circulation, ensuring sufficient developer presence at the measurement position without requiring additional developer quantity in the system
Solution Approach 2:
The patent introduces a reflection plate as an intermediary element that reflects developer toward the sensor position. This intermediary structure ensures that adequate developer reaches the measurement area by redirecting the circulation flow, thereby improving measurement accuracy without increasing the overall developer amount required in the system
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
The solution effectively stabilizes developer discharge and maintains a consistent developer amount, improving image concentration and reducing image unevenness, even during changes in process speed, thereby preventing defective images and excessive developer consumption.
Implementation Method 1
a first stir member that stirs and conveys the developer in the first convey chamber in a rotational axis direction
Implementation Method 2
a second stir member that is composed of a rotational shaft and a spiral blade formed on an outer circumference of the rotational shaft, stirs and conveys the developer in the second convey chamber in a direction opposite to the first stir member
Implementation Method 3
the second stir member is provided with a restriction portion that is disposed in a downstream of the connection portion with respect to the second stir member to face the developer discharge opening in a developer convey direction, and places a restriction on movement of the developer to the developer discharge opening
Implementation Method 4
a sensor disposition portion, where a toner concentration sensor is disposed on a bottom surface, is formed in an upstream with respect to the restriction portion in the developer convey direction
Data Source
AI summary
A developing apparatus according to the present disclosure is partitioned into a plurality of convey chambers which include a first convey chamber and a second convey chamber which are disposed substantially in parallel with each other, the second convey chamber has a U shape in section, a sensor disposition portion, where a toner concentration sensor is disposed on a bottom surface, is formed in an upstream with respect to a restriction portion in a developer convey direction, across a predetermined width in the developer convey direction including a detection surface of the toner concentration sensor, a distance between curved surface portions on both sides of a U-shaped inner wall surface and the second stir member is wider than another portion of the second stir chamber.