Printer Thickness Detection Using Pinch Arm Encoder

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Solution Overview

Problem

Thermal transfer printers face challenges in achieving optimal print quality due to incorrect thermal print head pressure settings, which are often not adjusted according to the thickness of the print media, leading to unsatisfactory print registration.

Innovation Solution

A printer system with a thickness detection module that includes a pinch arm assembly, encoder, and dual channel encoder sensor, which calculates the print media thickness using a conversion factor, allowing for automatic adjustment of thermal print head pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If thermal print head pressure is manually set by user, then device complexity is reduced, but print quality deteriorates due to incorrect pressure settings

Engineering Contradiction:

Improvepressure adjustment mechanismVSAvoidprint registration

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent replaces manual mechanical pressure adjustment with an automated optical measurement system. A laser distance sensor measures the distance between the thermal print head and print media, automatically calculating and adjusting the optimal pressure without user intervention, thereby improving print registration while maintaining simple device operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs self-adjustment of thermal print head pressure based on automatic thickness detection. The printer independently measures print media thickness using the laser sensor and adjusts pressure accordingly without requiring user knowledge or manual intervention, enabling the device to serve itself in optimizing print quality.

Inventive Principle:

Principle #25Self-service

2Manufacturing precision

If thermal print head pressure is increased, then print quality improves for thick media, but print registration deteriorates for thin media

Engineering Contradiction:

Improveprint qualityVSAvoidpressure adaptation to media thickness

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic pressure adjustment based on real-time thickness measurement. The system continuously adapts the thermal print head pressure according to the measured distance, allowing optimal pressure for each specific media thickness rather than using a fixed pressure setting, thereby maintaining both print quality and registration across varying media types.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the pressure parameter dynamically based on measured thickness. By using the laser distance sensor to determine media thickness, the controller adjusts the thermal print head pressure parameter accordingly, enabling the same device to handle both thin and thick media with appropriate pressure settings for each.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If laser distance sensor is added, then measurement precision improves, but device complexity increases

Engineering Contradiction:

Improvethickness detection accuracyVSAvoiddetection module

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the essential thickness measurement function needed for pressure adjustment. By using a simple laser distance sensor rather than a complex multi-parameter detection system, the invention achieves sufficient measurement precision for its specific purpose while minimizing the addition of complexity to the overall device.

Inventive Principle:

Principle #2Taking out (Extraction)

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 system ensures optimal thermal print head pressure based on detected print media thickness, improving print registration and quality by accurately measuring and responding to variations in media thickness.

Implementation Method 1

dual channel encoder sensor configured to detect rotation direction and encoder count and output signal representing encoder count

Methodology Applied

Scientific EffectOptical encoding:

Implementation Method 2

Encoder with number of circumferentially spaced line pairs is disposed at second end

Methodology Applied

Scientific EffectOptical grating measurement:

Implementation Method 3

biasing element for urging the pinch arm into engagement with at least a portion of the print media

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10071575B2Printers and methods for detecting print media thickness therein

Publication Date: 2018.09.11 HAND HELD PRODS INC

AI summary

Printer is provided having support base on which print media travels. Printer includes thickness detection module and processor. Thickness detection module includes pinch arm assembly with pinch arm having first and second ends, encoder, and proximate dual channel encoder sensor. First end is biased toward support base. Encoder with number of circumferentially spaced line pairs is disposed at second end. Pinch arm and encoder configured to rotate in response to engagement of pinch arm with at least print media portion. Dual channel encoder sensor configured to detect rotation direction and encoder count and output signal representing encoder count. Encoder count is number of circumferentially spaced line pairs that pass by dual channel encoder sensor as pinch arm and encoder rotate. Processor is communicatively coupled to dual channel encoder sensor and configured to receive signal and calculate print media thickness of portion from encoder count using conversion factor.