Welded Print Liquid Supply Unit for Accurate Level Sensing

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Solution Overview

Problem

Accurately sensing the remaining amount of print liquid in a reservoir is challenging due to issues like liquid bridging and environmental conditions, leading to unnecessary replacement and increased printing costs.

Innovation Solution

A print liquid supply unit with a sensor housed in a thermoplastic container, using welding techniques like laser or ultrasonic welding to create a waterproof seal, and employing a conductor sealed with a transmissive sealing material to ensure accurate liquid level sensing and minimize ink supply changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If liquid level sensors are used to sense remaining print liquid, then print liquid level can be detected, but sensing accuracy deteriorates due to liquid bridging and environmental conditions

Engineering Contradiction:
Improveliquid level sensing accuracyVSAvoidsensing reliability under environmental conditions
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

A transmissive sealing material is introduced as an intermediary between the conductor and the external environment. This sealing material allows optical signals to pass through while blocking liquid and environmental contaminants, enabling accurate liquid level detection without direct sensor exposure to harmful conditions

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces traditional mechanical or direct-contact liquid level sensing methods with optical detection through the transmissive sealing material. This substitution eliminates mechanical wear and contamination issues while maintaining sensing accuracy

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

2Productivity

If thermoplastic containers with welding are used, then manufacturing efficiency increases for high-volume production, but creating waterproof seals becomes more difficult

Engineering Contradiction:
Improvemanufacturing volume capacityVSAvoidwaterproof seal creation difficulty
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The patent utilizes the temperature-dependent properties of thermoplastic materials during welding. By controlling welding temperature and pressure parameters, the thermoplastic material melts and forms waterproof seals that integrate the conductor sealing within the container structure, enabling high-volume automated production

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The transmissive sealing material is integrated with the thermoplastic container structure through welding, creating a composite assembly that provides both structural integrity and waterproof sealing while maintaining optical transmissivity for sensor operation

Inventive Principle:
Principle #40Composite materials

3Measurement precision

If conductors are sealed with transmissive sealing material, then liquid level sensing accuracy improves, but the sealing process becomes more complex

Engineering Contradiction:
Improveliquid level detection accuracyVSAvoidsealing process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the conductor sealing function with the container welding process. The transmissive sealing material is integrated into the welding joint between container components, combining structural sealing and electrical isolation functions into a single manufacturing step, thereby reducing overall process complexity

Inventive Principle:
Principle #5Merging (Combining)

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

Enhances the accuracy of print liquid level sensing, reduces waste, and maintains print quality by allowing for individual color replacement and compatibility with high-volume manufacturing methods.

Implementation Method 1

The first housing component may be welded to the second housing component along a supply joint

Methodology Applied
Scientific EffectLaser welding: Laser Beam Welding

Implementation Method 2

welding techniques like laser or ultrasonic welding

Methodology Applied
Scientific EffectUltrasonic welding: Ultrasonic Vibration

Implementation Method 3

The electrical conductor may be sealed in the supply joint with a transmissive sealing material

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3687798B1Print liquid supply units
Publication Date: 2022.08.31 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3687798B1 patent drawingFigure 1
  • EP3687798B1 patent drawingFigure 2A~2C
  • EP3687798B1 patent drawingFigure 3

AI summary

Examples of a print liquid supply unit are described herein. In some examples, the print liquid supply unit includes a first housing component that is welded to a second housing component along a supply joint. In some examples, the print liquid supply unit also includes a conductor situated through the supply joint from an outside of the supply unit to an inside of the supply unit. In some examples, the conductor is sealed in the supply joint with a sealing material.