Thermal Printer Axial Downsizing via Nested Planetary Gear Mechanism
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Solution Overview
Problem
Existing thermal printers face challenges in downsizing in the axial direction due to the thickness limitations of the shaft support portion, speed reduction mechanism, and gear cover, which restricts their integration into portable terminals without compromising durability.
Innovation Solution
The thermal printer employs a planetary gear mechanism and a power transmission mechanism with idler gears made of resin materials, where the planetary gear mechanism protrudes to engage with the power transmission mechanism, allowing for a thinner design and reduced axial dimensions, and the gear layout is optimized to fit within the motor's outer shape, enabling compact sizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thicknesses of the shaft support portion, speed reduction mechanism, and gear cover are reduced to downsize the thermal printer in the axial direction, then the axial dimension is reduced, but the durability is compromised
Solution Approach 1:
The planetary gear mechanism is nested within the motor's outer shape, with the sun gear positioned at the center and planetary gears arranged around it. This nesting allows the speed reduction mechanism to be compactly integrated without increasing the axial dimension, while still providing sufficient thickness for durability. The gear cover is positioned to enclose the planetary gear mechanism, creating a nested structure that optimizes space utilization.
Solution Approach 2:
The invention transitions from a conventional two-step gear arrangement to a planetary gear mechanism that utilizes radial space more efficiently. By arranging gears in a radial configuration rather than a linear axial sequence, the speed reduction function is achieved within a smaller axial envelope, effectively moving the problem solution from one dimension (axial stacking) to another (radial distribution).
2Device complexity
If a conventional two-step gear speed reduction mechanism is used, then the structure is simple, but the axial dimension increases limiting downsizing
Solution Approach 1:
The planetary gear mechanism嵌套s the sun gear, planetary gears, and ring gear into a compact configuration where multiple gear stages occur simultaneously rather than sequentially. This nesting allows the speed reduction function to be achieved in a single axial layer rather than requiring multiple stacked gear stages, significantly reducing the axial dimension while maintaining structural coherence.
Solution Approach 2:
The invention merges multiple gear reduction stages into a single integrated planetary gear mechanism. Instead of using separate two-step gears arranged axially, the planetary mechanism combines sun gear, planetary gears, and ring gear into one unified structure that performs speed reduction in a compact package, eliminating the need for multiple discrete gear stages along the axial direction.
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 allows for significant downsizing of the thermal printer in the axial direction while maintaining durability and reducing noise, enhancing design flexibility and reducing the overall size of portable terminals.
Implementation Method 1
a planetary gear mechanism which is arranged on the inner side of the frame in the axial direction with respect to the shaft support portion and is configured to reduce power of the drive source
Implementation Method 2
The thermal head includes a heating element. The heating element of the thermal head is caused to generate heat as appropriate
Implementation Method 3
The platen roller is configured to feed the recording paper by nipping the recording paper with the thermal head
Data Source
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AI summary
A printer includes a platen roller (23) configured to feed recording paper (P) by nipping the recording paper (P) with a thermal head (21); a frame (31) which includes a shaft support portion (33) configured to support the platen roller (23) so that the platen roller (23) is rotatable about an axis direction thereof; a drive source (61) arranged on an inner side of the frame (31) in the axial direction with respect to the shaft support portion (33); a planetary gear mechanism (65, 66) which is arranged on the inner side of the frame (31) in the axial direction with respect to the shaft support portion (33) and is configured to reduce power of the drive source (61); and a power transmission mechanism (93) which is arranged on an outer side of the frame (31) in the axial direction with respect to the shaft support portion (33) and is configured to transmit power of the planetary gear mechanism (65, 66) to the platen roller (23).