Developing Device Developer Discharge Mechanism
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Solution Overview
Problem
Existing image forming apparatuses with developing devices using two-component or one-component developers face issues with developer scattering during replenishment and discharge, leading to unstable developer supply, increased maintenance costs, and image defects like scumming and toner scattering due to carrier deterioration.
Innovation Solution
A developing device with a developer carrier, supply conveyance path, circulation conveyance path, and a developer discharge mechanism that regulates the developer amount by discharging excess developer when it reaches a predetermined height level, preventing scattering and ensuring stable supply to the latent image carrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the developer discharge port is provided in the middle of the developer supply region, then the developer bulk increases can be discharged effectively, but the scattered developer is discharged even when the developer amount is appropriate or insufficient
Solution Approach 1:
The supply conveyance path is divided into an upstream section and a downstream section, with the developer discharge port positioned specifically in the downstream section. This segmentation allows the system to discharge accumulated developer bulk effectively while preventing the discharge of scattered developer that occurs in the upstream supply region, thereby resolving the contradiction between reliable developer supply and harmful scattered developer discharge.
2Quantity of substance
If developer is discharged from the discharge port when bulk exceeds height level, then excess developer is removed, but developer may be discharged even when amount is equal to or lower than appropriate amount
Solution Approach 1:
The developer discharge port is positioned in the downstream section of the supply conveyance path, where developer accumulation naturally occurs before reaching the development section. This preliminary positioning allows the system to discharge excess developer bulk before it can cause supply instability, while the strategic location prevents unnecessary discharge when developer amount is appropriate or insufficient, as the discharge port only activates when bulk accumulates to the height level in the downstream section.
3Adaptability or versatility
If pre-mixed developer is replenished to maintain toner density, then carrier replacement is achieved, but developer scattering occurs during replenishment and discharge
Solution Approach 1:
The developer discharge port extracts and removes the scattered developer and excess bulk from the supply conveyance path at a strategic location in the downstream section. By taking out the problematic scattered developer and accumulated bulk, the system maintains the carrier replacement capability through pre-mixed developer replenishment while eliminating the harmful scattering effect that occurs during replenishment and discharge operations.
Data Source
AI summary
A developing device capable of preventing scattered developer from being discharged and of stably supplying a developer to a latent image carrier by preventing the developer from being discharged despite that the amount of developer within the developing device is not increased, and an image forming apparatus including the developing device. When the bulk of the developer existing in the vicinity of the downstream end in the conveyance direction of the supply conveyance path exceeds the height level of the developer discharge port, the developer that has reached the height level of the developer discharge port is discharged to the outside of the developing device by the developer discharge port and developer conveyance path serving as the developer discharge device.