Overmolded Fluid Level Sensor Assembly

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Solution Overview

Problem

Existing fluid level sensors used in printing devices to monitor the level of printable fluid in reservoirs are often complex and expensive, leading to inaccurate readings and consumer dissatisfaction.

Innovation Solution

A method of forming a fluid level sensor involving an array of heating elements and sensors coupled to a substrate, with an electrical interface and conductive wire, overmolded with an epoxy molding compound to create a cost-effective and reliable sensing system that can accurately detect fluid levels in reservoirs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If existing fluid level sensors are used in printing devices, then fluid level monitoring is achieved, but the sensors are complex and expensive leading to inaccurate readings and consumer dissatisfaction

Engineering Contradiction:
Improvefluid level sensing accuracyVSAvoidsensor structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the heating element array and temperature sensor array into a single integrated sensor assembly that is overmolded together with the electrical interface and conductive wires. This merging of multiple components into one unified structure simplifies the device complexity while maintaining accurate fluid level detection through the differential temperature measurement principle.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If existing fluid level sensors are used in printing devices, then fluid level monitoring is achieved, but the sensors are expensive to produce

Engineering Contradiction:
Improvesensing system reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs overmolding technology to pre-assemble and encapsulate the heating elements, temperature sensors, electrical interface, and conductive wires into a single integrated unit before final installation. This preliminary assembly action ensures proper alignment and protection of sensitive components, improving reliability while reducing manual assembly costs and manufacturing complexity.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If heating elements and sensors are coupled to substrate, then fluid level detection is enabled, but manufacturing complexity increases

Engineering Contradiction:
Improvefluid level detection accuracyVSAvoidassembly complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the substrate-mounted heating elements, temperature sensors, electrical interface, and conductive wires into a single overmolded assembly. This integration eliminates multiple separate assembly steps and reduces the number of individual components that need to be handled separately, thereby reducing manufacturing complexity while preserving the differential temperature measurement capability for accurate fluid level detection.

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

The solution provides a low-cost, high-performance fluid level sensing system that is more economical to produce and offers superior accuracy and reliability in monitoring fluid levels, enhancing user experience by reducing manufacturing complexity and improving sensing precision.

Implementation Method 1

an array of heating elements and sensors coupled to a first side of a substrate, the sensors juxtaposed to the heating elements such that the heating elements provide heat for the sensors to detect

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3446076B1Over-molded fluid level sensor and method of forming the same
Publication Date: 2021.06.02 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3446076B1 patent drawingFigure 1A~2
  • EP3446076B1 patent drawingFigure 3~5
  • EP3446076B1 patent drawingFigure 6~8

AI summary

A method of forming a fluid level sensor includes coupling an array of heating elements and sensors to a first side of a substrate. A second side of the substrate is coupled to a carrier. The method also includes coupling an electrical interface to the carrier and electrically coupling the array to the electrical interface via a conductive wire. The method further includes overmolding the electrical interface, the first side of the substrate, and the conductive wire to form an overmolded fluid level sensor. The carrier may be coupled to the second side of the substrate and the electrical interface via a releasable adhesive and may be removed after overmolding the fluid level sensor.