Membrane-Integrated Active Circuits for Fluid Recirculation

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Solution Overview

Problem

Existing fluid ejection devices face challenges in efficiently recirculating fluid to prevent stagnation and prolong the life of fluid actuators while maintaining image quality, as active circuit elements are typically separated from fluidic regions, leading to inefficiencies.

Innovation Solution

The integration of active circuit elements on a thinner membrane adjacent to a fluid recirculation channel allows for controlled fluid ejection and recirculation, forming fluid ejection chambers and micro-recirculation chambers that are fluidically coupled, enabling fluid to be recirculated and preventing stagnation, thus prolonging actuator life and enhancing image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If active circuit elements are separated from fluidic regions, then device reliability is improved, but fluid recirculation efficiency deteriorates

Engineering Contradiction:
Improvedevice reliabilityVSAvoidfluid recirculation efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent merges active circuit elements with fluidic regions by forming circuit elements directly on the membrane within the fluidic die. This integration allows the circuit elements to be positioned adjacent to fluid recirculation channels, enabling efficient control of fluid ejection and recirculation while maintaining device reliability through proper isolation structures.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent segments the fluidic die into distinct regions including fluid ejection chambers, fluid recirculation channels, and micro-recirculation chambers. This segmentation allows different functional zones to operate independently while being integrated on the same membrane, resolving the contradiction between reliability and recirculation efficiency.

Inventive Principle:
Principle #1Segmentation

2Productivity

If active circuit elements are integrated on a thinner membrane, then fluid ejection efficiency is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvefluid ejection efficiencyVSAvoidmanufacturing complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent utilizes the vertical dimension by forming a multi-layer structure on the membrane with different layers serving different functions. The membrane itself is made thinner to improve fluid ejection efficiency, while circuit elements are formed in subsequent layers above the membrane, resolving the manufacturing complexity issue through vertical stacking rather than horizontal expansion.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent employs a thin membrane as the substrate for forming circuit elements and fluidic structures. This thin membrane enables efficient fluid ejection by reducing the distance fluid must travel, while the membrane serves as a flexible foundation that can be manufactured using standard semiconductor fabrication processes, balancing performance with manufacturability.

Inventive Principle:
Principle #30Flexible shells and thin films

3Duration of action of stationary object

If fluid recirculation is implemented, then actuator life is prolonged, but device complexity increases

Engineering Contradiction:
Improveactuator lifeVSAvoiddevice complexity
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent implements nested chambers where micro-recirculation chambers are formed within or adjacent to fluid ejection chambers. This nesting allows fluid to recirculate through multiple pathways without requiring separate external recirculation systems, prolonging actuator life while minimizing the increase in device complexity through space-efficient design.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent designs the membrane and associated structures to serve multiple functions: they form both fluid ejection chambers and fluid recirculation channels, and provide both structural support and electrical isolation. This multi-functionality allows fluid recirculation to be implemented without proportionally increasing device complexity, as existing structures are utilized for multiple purposes.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4232290B1Active circuit elements on a membrane
Publication Date: 2026.01.21 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP4232290B1 patent drawingFigure 1A~1B
  • EP4232290B1 patent drawingFigure 2A~2B
  • EP4232290B1 patent drawingFigure 3

AI summary

According to examples, an apparatus may include a substrate having a fluid recirculation channel and a membrane adjacent to the fluid recirculation channel, in which the membrane is portion of the substrate having a smaller thickness than other portions of the substrate. The apparatus may also include a component layer, in which a fluid ejection chamber may be formed in the component layer. The fluid ejection chamber may include a nozzle and fluid may be received into the fluid ejection chamber through an inlet port and recirculated to the fluid recirculation channel through an outlet port. The apparatus may further include active circuit elements formed on the membrane, in which the active circuit elements may control ejection of fluid from the fluid ejection chamber through the nozzle.