Rotary Encoder Code Wheel Positioning for Compact Printers
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Solution Overview
Problem
In printing apparatuses, the conveyance accuracy of print media is affected by the width of the device, as the coaxial placement of a code wheel with the conveyance roller makes it difficult to reduce the device width due to interference with the carriage and printhead, leading to increased device width and complexity.
Innovation Solution
A printing apparatus design where the code wheel is provided coaxially with the conveyance roller, allowing the carriage to overlap the code wheel in a direction perpendicular to the axial direction, reducing the device width by positioning the code wheel inside the moving range of the carriage, and using a rotary encoder with a reduced diameter code wheel and optimized light receiving element array to maintain detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the code wheel is provided coaxially with the conveyance roller, then the detection accuracy of the rotation amount is improved and the apparatus is hardly affected by gear backlash, but the device width increases because the code wheel must be disposed outside the moving range of the carriage
Solution Approach 1:
The code wheel is positioned in the vertical direction (Z-axis) overlapping with the carriage's moving path, rather than being displaced in the horizontal direction (Y-axis). This dimensional repositioning allows the code wheel to be located within the carriage's moving range without causing interference, thereby reducing device width while maintaining coaxial alignment with the conveyance roller for accurate rotation detection
Solution Approach 2:
The code wheel is nested within the moving range of the carriage by positioning it in the vertical direction. The carriage moves horizontally along rails while the code wheel is vertically positioned to overlap with this moving path, allowing the code wheel to be contained within the overall device footprint without requiring additional horizontal space
2Reliability
If the code wheel is disposed outside the moving range of the carriage, then interference between the carriage and code wheel is avoided, but the device width cannot be reduced
Solution Approach 1:
Instead of positioning the code wheel outside the carriage's horizontal moving range (Y-axis direction), the code wheel is positioned in the vertical direction (Z-axis) to overlap with the carriage's moving path. This allows the code wheel to be within the device footprint while the carriage's horizontal movement does not cause interference, as the carriage passes through the vertical space occupied by the code wheel
3Adaptability or versatility
If the width of the carriage is increased, then the printhead can support wider printing, but the code wheel needs to be disposed farther outside, making it difficult to reduce device width
Solution Approach 1:
The code wheel is positioned in the vertical direction overlapping with the carriage's moving path, decoupling the carriage width from the code wheel positioning requirements. This allows the carriage to be designed for wide printing capability without necessarily increasing device width, as the code wheel is positioned vertically rather than horizontally outside the carriage range
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 design reduces the device width while maintaining high conveyance accuracy and image quality, allowing for a more compact printing apparatus without compromising the detection resolution or increasing the device height.
Implementation Method 1
a detecting unit configured to detect a rotation amount of the conveyance roller, wherein the detecting unit comprises a rotary encoder including a code wheel provided coaxially with the conveyance roller
Data Source
AI summary
A printing apparatus includes a conveyance roller conveying a print medium, a printhead printing an image on the print medium, a carriage supporting the printhead and movable in a direction parallel to an axial direction of the conveyance roller, and a detecting unit detecting a rotation amount of the conveyance roller. The detecting unit is a rotary encoder including a code wheel provided coaxially with the conveyance roller. The carriage can move to a position at which the carriage overlaps the code wheel in a direction perpendicular to the axial direction of the conveyance roller.