Printhead Drive Circuit Merging for Resolution Adaptation

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Solution Overview

Problem

Conventional inkjet heater chip designs require unique ASICs and drivers for each vertical resolution, leading to increased development resources and time to market, making them less suitable for designs with shorter product life cycles or customized needs.

Innovation Solution

A printhead architecture with fluid vias and heating elements organized into primitive groups, allowing for a common electrical interface that adapts to different print resolutions by calculating the number of primitive groups based on the print resolution, enabling a single base chip to support multiple resolutions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional printheads with separate drive circuits for each nozzle are used, then each nozzle can be controlled independently, but the device complexity and manufacturing cost increase significantly

Engineering Contradiction:
ImproveIndependent nozzle controlVSAvoidCircuit structure complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent merges multiple drive circuits into a single common drive circuit that serves all nozzles. The control signal is applied to a common electrode, and individual nozzle activation is achieved by controlling the potential of shared electrodes, thereby reducing circuit complexity while maintaining independent control capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The common drive circuit is designed to serve multiple functions: it can control all nozzles collectively and also selectively activate individual nozzles by adjusting electrode potentials. This multi-functional design eliminates the need for separate dedicated circuits for each nozzle.

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

2Manufacturing precision

If separate drive circuits are provided for each nozzle, then precise control of each nozzle is achieved, but the manufacturing cost and device size increase

Engineering Contradiction:
ImproveNozzle control precisionVSAvoidManufacturing cost and complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Multiple separate drive circuits are merged into a single common drive circuit structure. The circuit controls multiple nozzles by utilizing shared electrodes and controlling electrode potentials, thereby reducing manufacturing complexity and cost while preserving precise control capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention changes the control parameter from individual circuit outputs to electrode potentials. By controlling the potential difference between the common electrode and shared electrodes, precise nozzle control is achieved through electrical parameter modulation rather than separate circuit control.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If a large number of nozzles are arranged in the printhead, then printing productivity increases, but the risk of liquid ejection from defective nozzles affecting adjacent nozzles increases

Engineering Contradiction:
ImprovePrinting speed and efficiencyVSAvoidEjection control reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The invention applies local quality control by enabling independent potential control of shared electrodes associated with specific nozzle groups. When a defective nozzle is detected, the potential of its associated shared electrode can be adjusted locally to prevent liquid ejection from that specific nozzle without affecting other nozzles.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

Shared electrodes act as intermediaries between the common drive circuit and multiple nozzles. By controlling the potential of these intermediary electrodes, the system can selectively activate or deactivate specific nozzles, providing a mechanism to isolate defective nozzles and prevent cross-contamination.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Manufacturing precision

If nozzle openings are made small to achieve fine printing resolution, then dot size decreases and resolution improves, but the likelihood of liquid ejection from defective nozzles spreading to adjacent nozzles increases

Engineering Contradiction:
ImprovePrinting resolutionVSAvoidLiquid spread from defective nozzles
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The control system applies local quality management by enabling independent control of electrode potentials for different nozzle regions. When liquid ejection from a defective nozzle is detected, the system can locally adjust the potential of associated electrodes to stop ejection from that specific nozzle, preventing liquid spread to adjacent nozzles despite their close proximity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system incorporates feedback mechanisms to detect defective nozzles and liquid ejection issues. Based on this feedback, the control circuit dynamically adjusts electrode potentials to prevent harmful liquid spread, thereby maintaining high resolution while mitigating the risks associated with small nozzle openings.

Inventive Principle:
Principle #23Feedback

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

This approach enables shorter development cycles and customized designs by simplifying print engine development and manufacturing, allowing a single base chip to drive heads of multiple resolutions without changing the electrical interface.

Implementation Method 1

a drive circuit which forms liquid droplets by applying a voltage to the liquid to be ejected from the nozzle and controls ejection of the liquid droplets

Methodology Applied
Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentEP3186085B1Printhead and inkjet printer
Publication Date: 2019.10.09 FUNAI ELECTRIC CO LTD
  • EP3186085B1 patent drawingFigure 1
  • EP3186085B1 patent drawingFigure 2
  • EP3186085B1 patent drawingFigure 3

AI summary

A printhead (10) including one or more fluid vias (110) in fluid communication with a fluid supply, each of the one or more fluid vias (110) being associated with a first number of heating elements, the heating elements being divided into groups of a second number of heating elements so as to form a number of primitive groups, and an electrical interface having at least one shift register that receives primitive address data to allow for selective application of electrical signals to the heating elements so that fluid is ejected from the printhead (10) in accordance with image data, the number of primitive groups being dependent on the print resolution of the printhead (10) so that a number of bits required for the at least one shift register to address each heater is independent of the print resolution of the printhead (10).