Inkjet Head Unit Positioning via Inclined Groove Contact
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Solution Overview
Problem
In sheet digital printing apparatuses, accurate positioning of the inkjet nozzle head is hindered by slight accuracy errors between tapered pins and holes, leading to rattling or inaccurate positioning due to mismatched angles and sizes.
Innovation Solution
The use of three blocks with inclined positioning grooves and three pins that come into two-point contact with the inclined surfaces, allowing for precise positioning of the head unit without requiring high accuracy in the complementary shape of the pins and holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tapered pins and tapered holes are used for positioning, then positioning precision can be improved, but manufacturing accuracy requirements increase significantly
Solution Approach 1:
The positioning function is segmented into multiple independent pin-groove pairs (three pins with three blocks) instead of relying on a single tapered pin-hole interface. This segmentation distributes the positioning requirement across multiple simpler elements, reducing the cumulative accuracy burden on each individual component while maintaining overall positioning precision.
Solution Approach 2:
Instead of using tapered shapes that require precise complementary fitting, the invention inverts the approach by using inclined surfaces that guide the pins into proper positioning through controlled contact. The inclination angle provides self-alignment functionality, eliminating the need for high-precision complementary taper matching.
2Measurement precision
If tapered pin and hole matching is used, then positioning accuracy can be achieved, but rattling occurs due to slight accuracy errors
Solution Approach 1:
The inclined surfaces on the blocks provide self-aligning functionality that automatically compensates for minor positioning errors. As the pins engage with the inclined surfaces, the geometry itself guides the components into proper alignment, eliminating rattling without requiring external adjustment mechanisms or high-precision manufacturing.
Solution Approach 2:
The invention changes the geometric parameters from tapered shapes to inclined surfaces with specific angles. This parameter change transforms the positioning mechanism from one requiring precise interference fitting to one that uses controlled angular contact, thereby eliminating rattling while maintaining positioning accuracy.
3Reliability
If three blocks with inclined surfaces and three pins are used, then positioning stability is improved, but device complexity increases
Solution Approach 1:
Each pin-block pair serves multiple functions simultaneously: positioning, alignment, and stability provision. The inclined surfaces provide both the positioning geometry and the self-aligning mechanism in a single integrated feature, reducing the need for separate adjustment mechanisms and simplifying the overall device structure.
Data Source
AI summary
An image forming apparatus includes a conveyance part, a head unit, a distance changing part, three blocks and three pins. The distance changing part moves the head unit between a printing position where a printing operation is performed and a retreat position separated away from the conveyance part farther than the printing position. The three blocks are provided in one of the conveyance part and the head unit at intervals in the conveyance direction and a width direction crossing the conveyance direction. The three pins are provided in the other of the conveyance part and the head unit at positions facing the three blocks. Each of the three blocks has a positioning groove having a pair of inclined surfaces. The pins come into two-point contact with the inclined surfaces of the blocks in a state where the head unit is positioned in the printing position.