Belt Unit Roller Alignment for Image Forming Apparatus
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Solution Overview
Problem
Image forming apparatuses with endless belts face challenges in preventing lateral shifting, as existing methods either require precise manufacturing controls, risk damage from stress accumulation, or lead to misalignment due to distortion, affecting belt cleaning performance.
Innovation Solution
The apparatus employs a main assembly with a rail member to precisely position and guide rollers with a wrapping angle greater than 90°, ensuring the belt driving roller remains aligned and reducing lateral shifting forces without the need to change the belt driving roller's angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the endless belt is suspended by rollers with varying diameter (center largest, ends smaller) to control lateral shifting, then the belt remains centered, but the belt portions supported by smaller diameter portions slacken and fail to be properly centered
Solution Approach 1:
The patent applies local quality by providing different diameter portions at specific locations on the roller. The first diameter portion (center) has a larger diameter to provide upward support force, while the second diameter portion (end) has a smaller diameter to reduce support force. This localized variation in roller diameter creates a force distribution that counteracts the belt's natural tendency to shift laterally, ensuring the belt remains centered without slackening.
2Weight of moving object
If the endless belt is extremely thin to reduce weight, then weight is reduced, but the belt is overcome by the force causing convergence toward center and the center portion wrinkles
Solution Approach 1:
The patent uses the anti-weight principle by creating a counterbalancing force through the varying diameter roller portions. The larger center portion of the roller provides an upward support force that counteracts the downward force causing the thin belt to converge and wrinkle at the center. This counterforce distributes the belt more evenly, preventing wrinkles while maintaining the thin, lightweight construction.
3Manufacturing precision
If the manufacturing process is strictly controlled with precise rollers and parallelism to prevent lateral shifting, then lateral shifting is controlled, but the force causing lateral shift accumulates stress in the rib, causing the rib to jump or break
Solution Approach 1:
The patent applies parameter changes by modifying the roller diameter parameter along its length. Instead of using uniformly precise rollers that create high lateral forces, the roller diameter varies from the center to the ends. This parameter variation changes the force distribution, reducing the lateral shifting force and the resulting stress accumulation in the belt rib, thereby preventing rib failure.
4Manufacturing precision
If the rollers are adjusted in terms of parallelism during assembly to cancel lateral shift tendency, then lateral shifting is reduced, but distortion occurs over time causing the belt to shift and the rib to creep onto the regulating member
Solution Approach 1:
The patent applies preliminary action by pre-configuring the roller with varying diameter portions during manufacturing, before assembly. This preliminary design of the roller geometry pre-establishes the force distribution needed to counteract lateral shifting, eliminating the need for precise post-assembly adjustments. The varying diameter roller maintains stable belt centering over time without requiring repeated alignment adjustments, preventing distortion and rib creep.
Data Source
AI summary
An image forming apparatus assembly includes a main body, and a belt unit mounted to the main body and including an endless belt, a plurality of rollers including a first roller configured to apply a driving force to the belt and to stretch the belt, and a second roller around which the belt is wound with a wrapping angle not less than 90° and configured to stretch the belt, a frame configured to integrally support the rollers, a first engaging portion disposed in the frame and configured to position the first roller to the main body, and a second engaging portion disposed in the frame and configured to position the second roller to the main body. In addition, a guide member is configured to guide the belt unit and disposed in the main body, and including a first engaged portion engaged with the first engaging portion and a second engaged portion engaged with the second engaging portion.