Rolling Element Safety Assembly for Printhead Spacing

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Solution Overview

Problem

The challenge in printing systems is maintaining precise printhead-to-print medium spacing to ensure high print quality while preventing crashes between the printhead and the print medium, especially with thicker or irregularly shaped print media.

Innovation Solution

A safety assembly with a rolling element is positioned upstream of the printhead to detect and counteract upwards bending of the print medium, ensuring a consistent printhead-to-print medium spacing and preventing contact between the printhead and the print medium.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the printhead-to-print medium spacing is decreased to improve print quality, then print precision is improved, but the risk of crashes between printhead and print medium increases

Engineering Contradiction:
Improveprint precisionVSAvoidcrash risk
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The safety assembly is positioned upstream of the printhead to detect and correct print medium irregularities before they reach the printhead. This preliminary action prevents crashes while allowing the printhead to maintain optimal spacing for high print precision.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The safety assembly acts as an intermediary between the print medium and printhead. It detects upward bending of the print medium and applies corrective force to prevent contact with the printhead, enabling the system to maintain smaller printhead-to-medium spacing without increasing crash risk.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a safety assembly is added to prevent crashes, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improvecrash preventionVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The safety assembly uses a spring-loaded rolling element that automatically detects and corrects print medium irregularities through passive mechanical means. The spring provides automatic force adjustment without complex control systems, achieving reliable crash prevention with minimal added complexity.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention replaces complex active control systems with a simple passive mechanical safety assembly. The spring-loaded rolling element uses elastic potential energy storage and mechanical force to prevent crashes, eliminating the need for sensors, actuators, and control electronics that would increase device complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 safety assembly effectively maintains a predetermined printhead-to-print medium spacing, enhancing print quality and reliability by preventing crashes and ensuring consistent printing performance across various print media thicknesses.

Implementation Method 1

The spring is configured to store and release energy to provide a corrective force to the print medium when it bends upwards

Methodology Applied
Scientific EffectSpring (elastic potential energy): Spring

Data Source

PatentEP4076967B1Safety assembly with a rolling element
Publication Date: 2025.06.04 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP4076967B1 patent drawingFigure 1~2
  • EP4076967B1 patent drawingFigure 3a~3b
  • EP4076967B1 patent drawingFigure 4~5a

AI summary

Examples relate to printing systems comprising a safety assembly associated with a printhead. The safety assembly comprises a rolling element upstream of the printhead in the print medium advance direction to prevent a print medium from contacting the printhead.