Asymmetric Pulley Design for Image Reading Apparatus Speed Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image reading apparatuses face issues with speed changes due to roller and pulley eccentricities, leading to reading failures such as partial magnification ratio changes and color shifts, and require complex assembly and maintenance processes.
Innovation Solution
The apparatus employs a conveyance unit with a first and second driving roller, a driving source, and a transmission belt system where the outer diameter of the second pulley is smaller than the first, reducing speed changes by synchronizing angular velocities through pulley diameter ratios, thereby simplifying the configuration and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pulley and rollers are positioned such that the direction of eccentricity of the pulley and the same of the rollers are opposite to each other, then reading failures such as partial magnification ratio change and color shift are reduced, but the assembling process becomes complicated and maintenance efficiency decreases
Solution Approach 1:
The invention applies asymmetry by making the outer diameter of the second pulley smaller than the outer diameter of the first pulley. This asymmetric design creates different angular velocities for the pulleys that compensate for eccentricity effects without requiring precise phase alignment, thereby reducing reading failures while simplifying the assembly process.
Solution Approach 2:
The invention changes the parameter of pulley outer diameter to create different angular velocities. By setting the outer diameter of the second pulley smaller than the first, the system achieves speed compensation for eccentricity without requiring complex alignment procedures, thus improving reliability while reducing assembly complexity.
2Reliability
If a sensor or encoder is added to detect rotation change and maintain constant rotation speed, then reading accuracy is improved, but the structure of the apparatus becomes complicated and the size of the apparatus increases
Solution Approach 1:
The invention extracts and eliminates the need for sensors and encoders by using a passive mechanical solution. The asymmetric pulley design inherently compensates for rotation speed variations caused by eccentricity, removing the requirement for active detection and control systems, thus maintaining rotation speed stability while simplifying the apparatus structure.
Solution Approach 2:
The system achieves self-regulation of rotation speed through the asymmetric pulley configuration. The different angular velocities of the pulleys automatically compensate for eccentricity effects without requiring external sensors or control systems, allowing the apparatus to maintain constant rotation speed through its own mechanical design.
3Reliability
If a mark on the timing belt is detected to maintain constant rotation speed, then rotation speed stability is improved, but a change component in the direction of thrust of the timing belt acts as a disturbance component and affects the stability of the rotation speed
Solution Approach 1:
The invention removes the timing belt mark detection system entirely and replaces it with an asymmetric pulley design. This eliminates the disturbance caused by thrust direction changes in the timing belt while maintaining rotation speed stability through the mechanical advantage of different pulley diameters compensating for eccentricity.
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 configuration effectively reduces speed changes by up to 30% and prevents reading failures, enhancing the stability and efficiency of the image reading process without the need for complex alignment or additional sensors.
Implementation Method 1
a transmission belt wound around the first pulley and the second pulley
Data Source
AI summary
An image reading apparatus includes a conveyance unit including a first driving roller and a second driving roller to convey a sheet, an image reading unit to read an image on the conveyed sheet at a reading position between the first driving roller and the second driving roller in a sheet conveyance direction, and a driving source to output a driving force for driving the first driving roller and the second driving roller. A first pulley is fixed to the first driving roller, a second pulley is fixed to the second driving roller, and a transmission belt is wound around the first pulley and the second pulley. An outer diameter of a belt-wound-part of the second pulley is smaller than an outer diameter of a belt-wound-part of the first pulley, the belt-wound-parts of the first pulley and the second pully being parts around which the transmission belt is wound respectively.