Driving Device Non-Integer Gear Ratio Speed Control
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Solution Overview
Problem
Existing image forming apparatuses face issues with rotational speed inconsistency due to lateral shake of the driving force source shaft and eccentricity of gears, which cannot be effectively detected or controlled using existing methods, leading to unsatisfactory image quality.
Innovation Solution
A driving device comprising a motor, driving gear, photosensitive member gear, idler gear, code wheel gear, detecting means, and controlling means, where the rotation detection gear's rotation period is a non-integer multiple of the driving gear's rotation period, allowing for precise control of the motor's rotational speed to minimize the effects of gear eccentricity and lateral vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotary encoder is provided on the driving force source shaft to detect rotational speed, then the driving force source rotational speed can be controlled, but lateral shake of the shaft and fluctuation due to gear eccentricity cannot be detected, resulting in photosensitive member rotational speed inconstancy
Solution Approach 1:
The patent introduces an intermediary detection mechanism (rotation detection gear and phase sensor) that indirectly measures the photosensitive member's rotational speed through the gear train. This mediator allows detection of the actual output speed without directly measuring the driving force source, thereby capturing the effects of lateral shake and gear eccentricity that direct measurement misses.
Solution Approach 2:
The system implements feedback control by continuously comparing the detected photosensitive member rotational speed with the target speed and adjusting the driving force source accordingly. This closed-loop feedback enables correction of speed variations caused by mechanical imperfections like gear eccentricity and shaft lateral shake.
2Ease of manufacture
If idler gears are used to transmit rotational motion to the photosensitive member, then the gear train can be assembled, but face angle errors and gear eccentricity cause rotational speed inconstancy that cannot be indirectly detected
Solution Approach 1:
The patent uses the gear train itself as an intermediary measurement system. By placing a rotation detection gear within the existing gear train and using a phase sensor to detect its rotation, the system indirectly measures the photosensitive member's speed without requiring separate measurement equipment, thus capturing the cumulative effects of all gear errors including face angle errors and eccentricity.
Solution Approach 2:
The patent replaces direct mechanical coupling measurement with a combined mechanical-optical measurement system. Instead of relying solely on mechanical indicators, it uses optical detection (phase sensor detecting flag position) to measure rotational speed, providing more accurate detection of speed variations caused by mechanical imperfections.
3Device complexity
If the rotation period of the rotation detection gear is an integer multiple of the driving gear rotation period, then detection is simplified, but the effects of gear eccentricity and lateral vibration cannot be minimized
Solution Approach 1:
The patent deliberately creates an asymmetric relationship between the rotation detection gear and driving gear rotation periods, setting them to be non-integer multiples of each other. This asymmetric configuration prevents periodic reinforcement of vibration and eccentricity effects, thereby minimizing their impact on measurement accuracy and photosensitive member speed constancy.
Data Source
AI summary
A driving device for driving a driven member includes a driving source; a driving gear fixed to a rotation shaft of the driving source; at least one gear for transmitting rotational motion of the driving gear to the driven member; a rotation detection gear engaged with the at least one gear; a detector for detecting rotation of the rotation detection gear; and a controller for detecting an angular speed and a rotational phase of the rotation detection gear on the basis of information from the detector and for controlling the rotational speed of the driving source such that a rotation period of the rotation detection gear is a non-integer multiple of a rotation period of the driving gear.