Belt Alignment Mechanism for Stress Reduction in Image Forming Apparatus
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Solution Overview
Problem
The existing image forming apparatuses face issues with belt shift and stress concentration at the widthwise end portions of the endless belt, leading to fatigue failure and reduced lifetime, especially when cost reduction measures like thinning the belt thickness are implemented.
Innovation Solution
An automatic belt center alignment mechanism is introduced, utilizing sliding members with a tapered shape and tension springs to maintain balance and distribute frictional forces evenly, reducing stress concentration and alleviating load on the belt ends, while adjusting the diameter and contact portion widths of the stretching rollers to distribute stress effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If center alignment is carried out by sliding between the widthwise end portion of the belt and the sliding member, then the belt can be aligned at the center position, but a load is exerted on the widthwise end portion of the belt causing stress concentration
Solution Approach 1:
The sliding members are positioned asymmetrically relative to the belt width, with each sliding member engaging at different locations along the belt's widthwise direction. This asymmetric arrangement distributes the alignment load away from the extreme end portions, reducing stress concentration while maintaining alignment capability
Solution Approach 2:
The solution transitions from a one-dimensional sliding contact at the belt edge to a two-dimensional distributed contact system where multiple sliding members engage at different positions along the belt width, spreading the load across a larger area and reducing peak stresses
2Ease of manufacture
If the thickness of the belt is made thin for reducing the cost of the belt, then the cost is reduced, but rigidity of the belt lowers and loads to fatigue failure earlier
Solution Approach 1:
The stretching rollers are configured to apply predetermined tension to the belt before the belt enters the alignment mechanism, pre-stressing the belt to compensate for its reduced rigidity due to thinning, thereby preventing excessive deformation and fatigue failure during operation
Solution Approach 2:
The invention changes the mechanical parameters of the belt system by adjusting the tension force applied by the stretching rollers and the contact pressure of the sliding members, optimizing these parameters to maintain sufficient rigidity and fatigue resistance in the thinned belt
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 extends the lifetime of the endless belt and the entire image forming apparatus by reducing stress concentration and fatigue failure, while maintaining stable belt movement and image registration, even when belt thickness is minimized for cost reduction.
Implementation Method 1
a force for swinging (tilting) the steering belt by a sliding member slidable with an inner peripheral surface of a moving belt at each of end portions with respect to a widthwise direction of the belt is imparted to the steering roller
Implementation Method 2
a tiltable steering roller configured to adjust a position of said endless belt with respect to a widthwise direction, said steering roller including a sliding member provided non rotatably at a position adjacent to each of ends of said steering roller
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3~4
AI summary
An image forming apparatus includes an image forming portion, an endless belt and a plurality of stretching rollers. The stretching rollers includes a tiltable steering roller, a sliding member, a first stretching roller having a smallest diameter, and a second stretching roller having a largest diameter of the diameters. With respect to rotational axis directions of the stretching rollers, lengths of contact portions of the stretching rollers with the belt are shorter than a width of the belt, the length of the contact portion of the first stretching roller with the belt is a first length, the length of the contact portion of the second stretching roller with the belt is a second length shorter than the first length, and end positions of the contact portions of the first and second stretching rollers with respect to the rotational axis direction are different from each other.