Capacitive Load Driving Circuit Noise Isolation via Gate Driver Extraction

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Solution Overview

Problem

In liquid discharging apparatuses like ink jet printers, high oscillation frequencies in class-D amplifiers for ink jet heads lead to noise interference, affecting discharge accuracy and requiring careful component layout, but existing solutions do not adequately address noise prevention in capacitive load driving circuits.

Innovation Solution

The implementation of a capacitive load driving circuit with a feedback circuit, a transistor, and a low pass filter, where the gate driver is positioned outside the shortest path between the feedback terminal and the modulation portion, and the feedback signal is sent back in a high frequency band, reducing noise interference and improving modulation signal accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high oscillation frequency is used in class-D amplifier for ink jet head, then discharge accuracy is improved, but noise interference increases

Engineering Contradiction:

Improvedischarge accuracyVSAvoidnoise interference

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the gate driver as a separate functional block from the feedback signal path. By positioning the gate driver outside the shortest straight path between the feedback terminal and the modulation portion, the harmful noise generated by the gate driver is separated from the sensitive feedback signal, thus reducing noise interference while maintaining high oscillation frequency for accurate discharge

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a specific wiring layout as an intermediary spatial arrangement between the gate driver and the feedback signal path. This spatial intermediary (the shortest straight path exclusion) acts as a noise isolation mechanism, allowing the high frequency operation to continue while preventing direct noise coupling into the feedback signal

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If gate driver is positioned close to modulation portion for compact layout, then device complexity is reduced, but noise interference increases

Engineering Contradiction:

Improvecomponent layoutVSAvoidnoise interference

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating a specific noise-sensitive zone (the shortest straight path between feedback terminal and modulation portion) and placing the gate driver outside this zone. This local spatial differentiation ensures that while components remain relatively compact, the gate driver does not introduce noise into the critical feedback signal path

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If feedback signal path is lengthened for noise isolation, then noise interference is reduced, but signal transmission delay increases

Engineering Contradiction:

Improvenoise interferenceVSAvoidsignal transmission delay

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent extracts the gate driver from the feedback signal path, creating a separate noise source region. This allows the feedback signal path to be optimized for minimum length and speed while the gate driver operates independently, achieving both noise isolation and fast signal transmission without compromise

Inventive Principle:

Principle #2Taking out (Extraction)

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 voltage control applied to piezoelectric elements, leading to improved liquid discharge accuracy and reduced noise influence, optimizing the frequency range of 1 MHz to 8 MHz for effective waveform generation and printing quality.

Implementation Method 1

a piezoelectric element which is displaced as the driving signal is applied

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a low pass filter which demodulates the amplification modulation signal and generates a driving signal

Methodology Applied

Scientific EffectElectronic filtering: Filter (electronic)

Implementation Method 3

a feedback terminal which is electrically connected to the modulation portion and the feedback circuit, in which, the feedback circuit generates a feedback signal based on the driving signal and sends back the feedback signal to the modulation portion

Methodology Applied

Scientific EffectFeedback control: Feedback

Data Source

PatentUS9764548B2Liquid discharging apparatus, head unit, capacitive load driving circuit, and integrated circuit device for capacitive load driving

Publication Date: 2017.09.19 SEIKO EPSON CORP

AI summary

There is provided an integrated circuit device; a feedback circuit; a transistor which generates an amplification modulation signal amplified from a modulation signal pulse-modulated from a source signal, based on an amplification control signal; a low pass filter which demodulates the amplification modulation signal and generates a driving signal for a capacitive load.