Worm Gear Transmission Torque Limiter for Inkjet Head Positioning
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Solution Overview
Problem
The existing lifting and lowering mechanism in inkjet type image forming apparatuses, utilizing a worm gear and worm wheel, suffers from an insufficient self-locking function due to varying frictional coefficients, leading to inaccurate positioning of the conveyance unit.
Innovation Solution
Incorporating a torque limiter as a resistance applying member within the transmission mechanism, which applies resistance to the rotation of the worm gear, ensuring a consistent self-locking function and precise positioning of the conveyance unit by regulating the frictional coefficient variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a worm gear and worm wheel are used for the lifting and lowering mechanism, then the self-locking function is provided, but the positioning precision is insufficient due to varying frictional coefficients
Solution Approach 1:
The patent changes the frictional coefficient parameter by introducing a resistance applying member that applies resistance to the worm gear rotation. This resistance compensates for variations in the frictional coefficient between worm gear teeth, ensuring consistent self-locking performance and improving positioning precision regardless of surface condition variations.
Solution Approach 2:
The resistance applying member acts as an intermediary element between the worm gear and the driving force. It introduces a controlled resistance that stabilizes the self-locking function, mediating the interaction between the worm gear and worm wheel to maintain reliable positioning despite frictional variations.
2Reliability
If the frictional coefficient varies due to surface conditions, then the self-locking function becomes insufficient, but adding resistance applying mechanisms increases device complexity
Solution Approach 1:
The resistance applying member is designed to perform multiple functions: it applies resistance to stabilize the self-locking function, compensates for frictional coefficient variations, and maintains positioning precision. This multi-functionality reduces the need for separate correction mechanisms, thereby limiting the increase in device complexity.
3Device complexity
If the worm gear and worm wheel are used without additional resistance, then the structure is simple, but the positioning accuracy deteriorates due to insufficient self-locking
Solution Approach 1:
The patent modifies the resistance parameter in the transmission system by adding a resistance applying member. This changes the overall frictional characteristics to provide sufficient self-locking force, thereby improving positioning accuracy while maintaining relative structural simplicity through a single added component.
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
The torque limiter ensures reliable self-locking and precise positioning of the conveyance unit, enhancing the apparatus's ability to maintain accurate positioning regardless of frictional coefficient variations, thereby improving the overall operational precision.
Implementation Method 1
The self-locking function is insufficient for positioning the conveyance unit correctly due to varying frictional coefficients between gear teeth
Data Source
AI summary
An image forming apparatus includes a head unit, a conveyance unit, a lifting and lowering mechanism, a drive source and a transmission mechanism. The head unit is provided with an inkjet head having a discharge opening through which an ink is discharged. The conveyance unit is supported in an upwardly and downwardly movable manner in directions close to and apart from the head unit from a lower side. The lifting and lowering mechanism is configured to lift and lower the conveyance unit. The drive source is configured to drive the lifting and lowering mechanism. The transmission mechanism is configured to transmit driving force from the drive source to the lifting and lowering mechanism. The transmission mechanism includes a warm gear, a warm wheel meshed with the warm gear and a resistance applying member configured to apply resistance to rotation of the warm gear.