Compact Platen Roller Motion System for Thermal Printing
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Solution Overview
Problem
Thermal printing mechanisms face challenges in reducing their global volume and production costs due to the thickness of the gearbox and heat dissipation issues, particularly with small diameter stepper motors.
Innovation Solution
The thermal printing mechanism simplifies the motion means by mounting the motor on the printer chassis with a gear axis parallel to the thermal printhead surface and perpendicular to the platen roller shaft, using a gear shaft with a spur gear and worm screw, and incorporating lateral alignment guides and conductive metallic chassis for heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small diameter stepper motor (10 mm) is used to reduce the printer size, then the motor dimensions are reduced, but heat dissipation becomes problematic
Solution Approach 1:
The motor is integrated directly into the printer chassis structure, merging the motor housing with the chassis. This allows the chassis to serve dual purposes: structural support and heat dissipation surface for the motor, eliminating the need for separate heat dissipation components.
Solution Approach 2:
The printer chassis is designed to perform multiple functions: it provides structural support, serves as a heat dissipation surface for both the motor and thermal head, and acts as a mounting platform. This multi-functionality resolves the heat dissipation problem of small motors without adding extra components.
2Ease of manufacture
If the motor is mounted parallel to the thermal printhead dotline (horizontal or vertical variant), then the motor positioning is simplified, but the gearbox thickness remains 7-8 mm and cannot be reduced
Solution Approach 1:
The motor axis is reoriented to be substantially perpendicular to the thermal printhead dotline, changing the traditional horizontal or vertical mounting arrangement. This dimensional change allows the gear train to be arranged in a different spatial configuration, reducing the gearbox thickness to approximately 5 mm while maintaining manufacturability.
3Length of stationary object
If the motor axis is perpendicular to the thermal printhead dotline, then the gearbox thickness is reduced to approximately 5 mm, but the motor mounting configuration becomes more complex
Solution Approach 1:
The motor is merged with the printer chassis as an integrated unit, where the chassis provides the mounting structure and alignment features. This integration simplifies the overall mounting configuration despite the perpendicular motor orientation, as separate mounting brackets and alignment mechanisms are eliminated.
4Temperature
If additional metal parts are mounted on the motor to dissipate heat, then heat dissipation is improved, but the overall device volume and production costs increase
Solution Approach 1:
The printer chassis is designed to serve as the heat dissipation surface for both the motor and thermal head, eliminating the need for additional heat dissipation components. This multi-functional design maintains compact device volume while effectively managing heat from small diameter motors.
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 reduces the total dimensions of the thermal printing mechanism, simplifies the construction, enhances reliability, and decreases production costs while maintaining effective heat dissipation.
Implementation Method 1
the printer chassis is metallic for rigidifying the thermal mechanism, dissipating the heat generated by the thermal printhead and the motor
Data Source
Figure 1~4
Figure 5~6
Figure 7~10
AI summary
Thermal printing mechanism according to the invention comprises: a printer chassis (1), a thermal printhead (2), a motor (3) for rotating a platen roller (4) with a motor spur gear (5), a platen roller (4) with a platen roller gear (6) mounted on it, said platen roller gear being a worm wheel able to engage with a worm screw. The motor (3) is mounted so as its gear axis is substantially parallel to the thermal printhead surface which is in contact with the platen roller (4), and perpendicular to the platen roller shaft (9). The thermal printing mechanism further comprises a gear shaft (10) mounted substantially parallel to the motor gear axis, said gear shaft (10) having at one end a spur gear (11) able to engage with the motor spur gear (5), and at the other end a worm screw (7), able to engage with the platen roller gear (6).