Carriage Guide Mechanism for Backlash Reduction in Image Scanners
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Solution Overview
Problem
Conventional image reading apparatuses experience backlash issues due to reaction forces during carriage movement, affecting the quality of reading images and increasing driving load, which complicates achieving high-definition readings and increases costs.
Innovation Solution
An image reading apparatus with a rack member, pinion gear, motor, urging member, and guide rail configuration, where the urging member presses the reading sensor unit toward the document positioning plate, balancing forces to prevent backlash and reduce driving load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the slider is separated from the rack member to reduce the size of the apparatus, then the apparatus size is reduced, but backlash occurs due to increased rotating force
Solution Approach 1:
The elastic member applies a preliminary urging force to the slider in the direction toward the rack member before the carriage moves. This preliminary action counteracts the rotating force that would otherwise cause the slider to separate from the rack member, preventing backlash from occurring in the first place while allowing the apparatus to maintain a compact size.
2Manufacturing precision
If an urging member is added to prevent backlash, then backlash is reduced, but the driving load increases
Solution Approach 1:
The invention converts the reaction force generated during carriage movement, which previously caused harmful slider separation and backlash, into a beneficial compressive force on the elastic member. This compressive force then generates the urging force needed to maintain slider-rack contact, transforming a harmful effect into a useful function without requiring additional driving load.
3Manufacturing precision
If the slider contacts the rack member tightly to prevent backlash, then backlash is reduced, but the driving load increases
Solution Approach 1:
Instead of using a rigid, fixed-contact system between the slider and rack member, the invention introduces an elastic member that creates a dynamic, flexible connection. This dynamic system allows the slider to maintain contact with the rack member through elastic urging while accommodating movement variations, reducing the driving load compared to rigid tight-contact systems.
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 stabilizes the reading sensor unit, reduces backlash, and decreases the driving load, enabling high-quality image acquisition while improving reading speed and reducing the number of parts and costs.
Implementation Method 1
an elastic member, which urges the slider in a direction toward the rack member by receiving a reaction force at the carriage
Data Source
AI summary
An image reading apparatus for reading a document placed on a document positioning plate using a reading sensor unit mounted on a carriage includes a rack member provided in an apparatus body and having rack teeth provided along the moving direction of the carriage, a pinion gear rotatably disposed on the carriage and meshed with the rack teeth, a motor mounted on the carriage and driving the pinion gear, an urging member disposed between the carriage and the reading sensor unit and urging the reading sensor unit toward the document positioning plate, a guide rail provided in the apparatus body and guiding movement of the carriage, and a guide portion provided on the carriage and engaged with the guide rail, wherein the guide portion is pressed toward the guide rail by receiving a reaction force of the urging member at the carriage.