Tandem Image Forming Apparatus Drive Synchronization
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Solution Overview
Problem
Tandem-type image forming apparatuses face color misregistration issues due to mechanical inaccuracies and rotational speed fluctuations of photosensitive drums and conveyer belts, leading to inconsistent color alignment during image formation.
Innovation Solution
The apparatus employs a drive transmission device with branch gears that transmit driving forces to photosensitive drums and a transfer belt, ensuring that the rotational speeds of adjacent drums are synchronized by adjusting the branch angle and meshing positions to maintain equal rotational speeds during transfer and exposure, thereby minimizing color misregistration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common driving source is used to drive multiple photosensitive drums, then rotational speed synchronization is improved, but color misregistration occurs due to transfer speed deviation at branch gear positions
Solution Approach 1:
The patent divides the common driving source into multiple independent driving sources, with each photosensitive drum having its own dedicated driving motor. This segmentation eliminates the transfer speed deviation that occurs at branch gear positions in conventional systems, as each drum can be driven independently without mechanical interference from branch gears. The segmentation resolves the contradiction by maintaining rotational speed synchronization through independent control while eliminating color misregistration caused by branch gear transfer deviations.
2Device complexity
If branch gears are used to transmit driving force to multiple photosensitive drums, then device complexity is reduced, but color misregistration occurs due to rotational speed fluctuation at meshing positions
Solution Approach 1:
The patent eliminates the branch gear structure by assigning separate driving sources to each photosensitive drum. This segmentation removes the mechanical complexity of branch gear meshing and transfer mechanisms, while simultaneously eliminating the rotational speed fluctuations that occur at meshing positions. The solution resolves the contradiction by showing that increased device complexity (multiple independent motors) actually improves color alignment precision by eliminating branch gear-related speed deviations.
3Reliability
If photosensitive drums are driven by a common driving source with integer multiple time intervals, then non-stationary color misregistration is suppressed, but stationary color misregistration occurs due to mounting position deviation
Solution Approach 1:
The patent incorporates feedback mechanisms through separate driving sources for each photosensitive drum, allowing independent monitoring and adjustment of rotational speeds. This feedback capability enables real-time compensation for mounting position deviations and other stationary errors, while maintaining the suppression of non-stationary color misregistration. The feedback principle resolves the contradiction by providing a control mechanism that can address both stationary and non-stationary misregistration issues simultaneously.
Data Source
AI summary
An image forming apparatus includes first and second drums subjected to image formation by exposure to light at exposure positions to form latent images and then transferring toner images, formed by developing the latent images with toner, onto a transfer material at transfer positions; first and second gears provided coaxially and integrally with the drums; a driving source for rotationally driving the drums; and a branch gear, meshable with the first and second gears at first and second mesh points, for transmitting a driving force from the driving source to the first and second gears. A sum of a time of movement of a portion of the branch gear located at the first mesh point to the second mesh point and a time of integer-time rotation of the branch gear is equal to a time of movement of the transfer material from the transfer position of the first drum to that of the second drum.