Thermal Printer Blade Return Mechanism for Jam Clearance

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Solution Overview

Problem

Existing thermal printers face challenges in efficiently eliminating paper jams between movable and fixed blades, particularly when the jam exceeds the gap formed between them, leading to low jam removal capability and preventing the printer cover from being opened, thus hindering operation.

Innovation Solution

A thermal printer with a printing unit featuring a drive mechanism, operation lever, and return mechanism that includes a clutch member, ratchet wheel, biasing member, and planetary gear system, allowing the movable blade to be returned to its standby position through multiple operations of the lever, ensuring effective paper jam clearance and enabling the printer cover to be opened.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a gap is formed between the movable blade and the fixed blade by one operation of the operation lever, then the load of the paper jam is removed, but when a paper jam larger than the gap occurs, it is difficult to completely remove the load of the paper jam and the movable blade may not be returned

Engineering Contradiction:
Improvepaper jam elimination capabilityVSAvoidmovable blade return reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The operation lever is designed to be operable multiple times in sequence. Each operation advances the movable blade toward the standby position by a fixed amount (the gap distance). By repeating this periodic action, even large paper jams can be eliminated step by step, ensuring the movable blade reliably returns to the standby position regardless of initial jam size.

Inventive Principle:
Principle #19Periodic action

2Device complexity

If a gap is formed between the fixed blade and the movable blade, then the movable blade can be returned to standby position with elastic restoring force of a spring, but when a paper jam larger than the gap occurs, it is difficult to completely remove the load and the cover cannot be opened

Engineering Contradiction:
Improve结构简单性VSAvoidjam removal efficiency
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The operation lever performs a preliminary action by forming a gap between the movable blade and fixed blade. This preliminary gap formation reduces the paper jam load to a manageable level, enabling the spring's elastic restoring force to then return the movable blade to the standby position. The cover can then be opened successfully.

Inventive Principle:
Principle #10Preliminary action

3Stability of the object's composition

If the movable blade stops at a position of riding on the fixed blade, then the state is maintained, but the cover of the printer cannot be opened and neither blade can be exposed

Engineering Contradiction:
Improveblade position stabilityVSAvoidcover opening capability
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The return process is segmented into discrete steps corresponding to multiple operation lever actions. Each operation advances the movable blade by a fixed gap distance toward the standby position. This segmentation allows the system to handle paper jams of varying sizes systematically, ensuring the blade eventually clears the fixed blade and the cover can be opened.

Inventive Principle:
Principle #1Segmentation

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 solution enhances the capability to easily eliminate paper jams by allowing the movable blade to be reliably returned to its standby position with repeated lever operations, ensuring the printer cover can be opened, thus improving operational efficiency and usability.

Implementation Method 1

a biasing member configured to bias the operation lever from the releasing position side toward the lock position

Methodology Applied
Scientific EffectElastic force: Elasticity

Data Source

PatentEP3677395B1Printing unit and thermal printer
Publication Date: 2021.11.03 SEIKO INSTR INC
  • EP3677395B1 patent drawingFigure 1
  • EP3677395B1 patent drawingFigure 2
  • EP3677395B1 patent drawingFigure 3

AI summary

A printing unit (8) includes: a head unit (5); a platen unit (4) separably combined with the head unit (5); a fixed blade (34) provided to the platen unit (4); a movable blade (22), which is provided to the head unit (5) and is relatively movable with respect to the fixed blade (34); a drive mechanism (24), which includes a drive rack (46) coupled to the movable blade (22), and moves the movable blade (22) between a standby position (P2) being separated from the fixed blade (34) and a cutting position (P1) at which the movable blade (22) rides on the fixed blade (34); an operation lever (25) being movable between a lock position (P3) and a releasing position (P5); and a return mechanism (26) configured to move the movable blade (22) from the cutting position (P1) toward the standby position (P2) side through intermediation of the drive rack (46) in association with the operation lever (25). The return mechanism (26) includes a lever returning mechanism (62), under the state in which movable blade (22) is stopped at the cutting position (PI), transmits motive power generated along with an operation of the operation lever (25) from the lock position (P3) toward the releasing position (P5) to the drive mechanism (24) to move the movable blade (22) toward the standby position (P2) and returns the operated operation lever (25) from the releasing position (P5) side to the lock position (P3).