Involute Spline Drive Transmission for Photosensitive Drum Accuracy

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Solution Overview

Problem

Current drive transmission systems for image forming apparatuses fail to simultaneously achieve high rotational accuracy for photosensitive drums and developing rollers, leading to image density unevenness due to lack of attention to positional accuracy between rotating bodies.

Innovation Solution

A drive transmission device utilizing two involute spline joints, where the first joint is coupled earlier than the second, with profile shifting and combined with a speed reduction mechanism to ensure rotational and positional accuracy, and dimensional tolerances are set to accommodate axis misalignment, specifically for photosensitive members and developing rollers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If separate drive transmission systems are used for photosensitive member and developing unit, then rotational accuracy of photosensitive member is improved, but device complexity increases and positional accuracy between rotating bodies deteriorates

Engineering Contradiction:

Improverotational accuracy of photosensitive memberVSAvoidcomplexity of drive transmission system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the drive transmission systems for the photosensitive member and developing unit into a single integrated system using one drive shaft with two involute spline joints. This merging approach maintains rotational accuracy for the photosensitive member while reducing device complexity and improving positional accuracy between rotating bodies compared to separate drive systems.

Inventive Principle:

Principle #5Merging (Combining)

2Measurement precision

If involute spline joint is used for photosensitive member, then rotational accuracy is improved, but positional accuracy between rotating bodies is not ensured

Engineering Contradiction:

Improverotational accuracyVSAvoidpositional accuracy between rotating bodies

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent employs involute spline joints for both the photosensitive member and developing unit on the same drive shaft, making the joint design universal. This multi-functional application ensures both rotational accuracy for each component and positional accuracy between them, as both joints share the same reference axis and manufacturing tolerances.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent specifies particular parameter ranges for the involute spline joints, including tooth profile parameters and dimensional tolerances, to simultaneously achieve rotational accuracy and positional accuracy. By controlling parameters such as the addendum modification coefficient and dimensional tolerances within specific ranges, both accuracy requirements are satisfied.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If different joint types are used for photosensitive member and developing unit, then rotational accuracy of photosensitive member is improved, but rotational fluctuations of developing unit increase

Engineering Contradiction:

Improverotational accuracy of photosensitive memberVSAvoidrotational stability of developing unit

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The patent uses the same type of involute spline joint for both the photosensitive member and developing unit, ensuring homogeneous coupling characteristics. This homogeneity provides consistent rotational stability for both components while maintaining high rotational accuracy for the photosensitive member, avoiding the rotational fluctuations that would result from mixing different joint types.

Inventive Principle:

Principle #33Homogeneity

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

This solution ensures high rotational accuracy and positional accuracy between the photosensitive drum and developing roller, reducing image density unevenness and improving image quality by minimizing rotational fluctuations and allowing for easy removability and maintenance of image forming units.

Implementation Method 1

A first involute spline joint to perform drive transmission to a primary rotating body to be driven and a second involute spline joint to perform drive transmission to secondary rotating body to be driven

Methodology Applied

Scientific EffectInvolute spline joint mechanism: Gear

Data Source

PatentUS8064801B2Drive transmission device, and image forming apparatus and process cartridge using same

Publication Date: 2011.11.22 RICOH CO LTD

AI summary

A drive transmission device that performs drive transmission through a plurality of systems and includes a first involute spline joint to perform drive transmission to a primary rotating body to be driven and a second involute spline joint to perform drive transmission to a secondary rotating body to be driven.