Head Unit Control Circuit Noise Isolation for Piezoelectric Ejection

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Solution Overview

Problem

Existing liquid ejecting devices, such as inkjet printers, face issues with abnormal ejection states due to failures in the ejecting section, leading to inaccurate dot formation and deteriorated image quality, primarily because noise contamination in the drive determination process affects the accuracy of determining the piezoelectric element's functionality.

Innovation Solution

The solution involves providing a determination circuit within the head unit to reduce noise interference and allowing the head unit to perform self-contained drive and diagnosis processes, using a third terminal to isolate potential changes in the drive signal from the instruction signal and incorporating a terminal arrangement that minimizes noise propagation, ensuring accurate determination and diagnosis of the piezoelectric element's electrical storage capability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If audio data is transmitted through the communication unit during the boot process, then the head unit can acquire audio data from the navigation device, but the boot process time is extended

Engineering Contradiction:
Improveaudio data acquisitionVSAvoidboot process time
Core Design Contradiction:
Loss of informationVSLoss of time

Solution Approach 1:

The boot process is segmented into two distinct phases: a first boot process that occurs before audio data transmission and a second boot process that occurs after. This segmentation allows the system to separate time-critical initialization tasks from audio data acquisition, ensuring that essential system startup functions complete quickly while audio data is fetched in the background during the second boot process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The head unit performs preliminary boot initialization tasks before attempting to acquire audio data from the navigation device. By completing essential system setup, driver initialization, and core functionality preparation in advance, the system ensures that the boot process is not delayed by audio data transmission, as the critical path is already established.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the head unit waits for the navigation device to be ready during the boot process, then audio data can be acquired, but the boot process is delayed

Engineering Contradiction:
Improveaudio data acquisition reliabilityVSAvoidboot process delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system dynamically adjusts the boot process timing and audio data acquisition strategy based on the readiness state of the navigation device. Rather than using a fixed waiting period, the head unit implements adaptive timing that responds to actual device availability, allowing the boot process to proceed efficiently while ensuring audio data is acquired when the navigation device is ready.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The head unit implements a feedback mechanism that monitors the navigation device's readiness status and adjusts the audio data acquisition timing accordingly. The system continuously checks whether the navigation device is ready and only initiates audio data transmission when confirmed, preventing unnecessary delays while ensuring reliable data acquisition.

Inventive Principle:
Principle #23Feedback

3Reliability

If the head unit resets during audio data transmission, then system stability can be maintained, but audio data may be lost or corrupted

Engineering Contradiction:
Improvesystem stabilityVSAvoidaudio data integrity
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The head unit implements protective measures before initiating audio data transmission, including establishing stable communication protocols, buffering mechanisms, and error checking procedures. These preemptive safeguards ensure that if a reset occurs during the boot process, the audio data transmission can resume without loss or corruption, maintaining both system stability and data integrity.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The system ensures continuous audio data acquisition across boot process resets by implementing persistent communication sessions and data buffering. Rather than losing progress when a reset occurs, the head unit maintains the ability to continue acquiring audio data from the navigation device, ensuring uninterrupted functionality and preventing data loss.

Inventive Principle:
Principle #20Continuity of useful action

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 configuration enhances the accuracy of determining and diagnosing the piezoelectric element's functionality, reducing the likelihood of malfunction and maintaining image quality by isolating noise and allowing for timely and appropriate stopping of the drive signal, thus preventing deterioration in image quality and safety.

Implementation Method 1

driving a piezoelectric element provided to the ejecting section using a drive signal to form an image on a recording medium

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP3393809B1Head unit control circuit
Publication Date: 2023.07.19 SEIKO EPSON CORP
  • EP3393809B1 patent drawingFigure 1
  • EP3393809B1 patent drawingFigure 2~3
  • EP3393809B1 patent drawingFigure 4~5

AI summary

A head unit control circuit controls a head unit, and is provided outside the head unit, the head unit including: an ejecting section that includes a piezoelectric element, and can eject a liquid corresponding to displacement of the piezoelectric element, the piezoelectric element being displaced corresponding to a change in potential of a drive signal when the drive signal has been supplied to the piezoelectric element; a determination circuit that determines whether or not the piezoelectric element has a predetermined electrical storage capability; and an ejection limit circuit that stops the supply of the drive signal to the piezoelectric element and limits the ejection of the liquid from the ejecting section when result of the determination is negative, the head unit control circuit including: a first terminal that outputs an instruction signal that instructs the head unit to execute the determination; a second terminal that outputs the drive signal; and a third terminal that is provided between the first terminal and the second terminal, the third terminal being smaller in potential change width than the second terminal when the ejecting section ejects the liquid.