Developing Device Sensor Holder for Accurate Toner Detection

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Solution Overview

Problem

Conventional developing devices in electrophotographic image forming apparatuses face issues with the toner concentration sensor position shifting from the target position during installation or maintenance, leading to inaccurate toner concentration detection and control.

Innovation Solution

A developing device with a sensor holder that holds the toner concentration sensor, utilizing a projection and hole configuration to accurately position the sensor within the developing case, ensuring consistent detection and control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the toner concentration sensor is installed in the developing case during producing or maintenance, then the sensor can detect toner concentration, but the position of the sensor shifts from the target position

Engineering Contradiction:
Improvetoner concentration detection accuracyVSAvoidsensor position accuracy
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

A sensor holder is introduced as an intermediary component between the toner concentration sensor and the developing case. The sensor holder includes a positioning projection that fits into a corresponding positioning hole in the developing case, ensuring the sensor is held at the correct target position during installation and maintenance operations.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The sensor holder is pre-equipped with a positioning projection that is designed to fit into the positioning hole of the developing case. This preliminary positioning structure ensures that when the sensor is installed, it automatically assumes the correct position without requiring complex adjustment procedures during maintenance or production.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If the toner concentration sensor position shifts, then installation is simpler, but the toner concentration detection and control vary

Engineering Contradiction:
Improvesensor installation easeVSAvoidtoner supply control reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The sensor holder serves as a mediator that simplifies installation by providing a pre-positioned mounting structure, while simultaneously ensuring reliable toner supply control through its positioning projection that maintains accurate sensor alignment with the developing case.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4261620B1Developing device, process cartridge, and image forming apparatus
Publication Date: 2025.07.30 RICOH CO LTD
  • EP4261620B1 patent drawingFigure 1
  • EP4261620B1 patent drawingFigure 2~3
  • EP4261620B1 patent drawingFigure 4(A)~5

AI summary

A developing device (13) includes a developing case (13k), a toner concentration sensor (13m), and a positioner (13s1). The developing case (13k) stores a developer containing toner and carrier to develop a latent image on a surface of an image bearer. The developing case (13k) includes at least a part of a conveyance path of the developer. The toner concentration sensor (13m) detects a toner concentration of the developer in the developing case (13k). The positioner (13s1) engages with an engaging portion (13n1) at a center of a sensor main section (13n) of the toner concentration sensor (13m) to determine a position of the sensor main section in the developing case (13k).