Flexible Circuit Board Noise Reduction in Liquid Discharge Heads

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Solution Overview

Problem

The LVDS transmission scheme in liquid discharge heads is susceptible to switching noise, which can disrupt data transmission and stability, especially when a large number of energy generating elements are driven simultaneously, leading to potential upsizing of the circuit board to mitigate noise interference.

Innovation Solution

A flexible circuit board design with differential transmission lines on one side and a voltage supply line on the other side, allowing for reduced noise influence during data transfer without upsizing, by positioning the lines to cancel out induced electromotive forces and using a guard line to further reduce interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the differential transmission line is positioned away from the voltage supply line to reduce switching noise influence, then the data transmission reliability is improved, but the circuit board size increases

Engineering Contradiction:

Improvedata transmission reliabilityVSAvoidcircuit board size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent transitions from a planar arrangement to a three-dimensional layered structure by providing differential transmission lines on one surface of the flexible circuit board and voltage supply lines on the opposite surface. This dimensional separation allows the signal lines and power lines to be electrically isolated without increasing the overall footprint area, thereby maintaining compact size while reducing switching noise interference.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent segments the circuit board into distinct functional layers: one surface dedicated to differential transmission lines for data communication and the opposite surface dedicated to voltage supply lines for power delivery. This segmentation separates the signal carrying function from the power delivery function, preventing electromagnetic interference while maintaining a compact overall structure.

Inventive Principle:

Principle #1Segmentation

2Productivity

If multiple energy generating elements are driven simultaneously to improve productivity, then the discharge speed is improved, but the switching noise influence increases

Engineering Contradiction:

Improvedischarge speedVSAvoidswitching noise influence

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

By moving the voltage supply lines to the opposite surface of the flexible circuit board from the differential transmission lines, the patent creates spatial separation that reduces electromagnetic coupling. This allows high-current switching operations for multiple energy generating elements without generating excessive noise that would interfere with sensitive data transmission, thus enabling high productivity while controlling harmful electromagnetic interference.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 effectively reduces noise interference in the LVDS transmission scheme, ensuring high-reliability data transfer and maintaining a compact apparatus size by equalizing induced electromotive forces and utilizing a guard line to prevent mutual interference between signal lines.

Implementation Method 1

providing a pair of differential transmission lines for transmitting differential transmission signals to the liquid discharge head substrate

Methodology Applied

Scientific EffectElectromagnetic signal transmission: Electromagnetic Induction

Implementation Method 2

providing a voltage supply line for supplying voltage to be applied to the energy generating elements to the liquid discharge head substrate

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

positioning the lines to cancel out induced electromotive forces and using a guard line to further reduce interference

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS8672452B2Liquid discharge head and circuit board

Publication Date: 2014.03.18 CANON KK

AI summary

A liquid discharge head includes a liquid discharge head substrate including a discharge port through which a liquid is discharged, and a plurality of energy generating elements that generate energy for discharging the liquid from the discharge port, and a circuit board having flexibility including a pair of differential transmission lines for transmitting differential transmission signals used as logical signals for driving the energy generating elements, to the liquid discharge head substrate, and a voltage supply line for supplying a voltage applied to the energy generating elements to obtain the energy, to the liquid discharge head substrate, wherein the pair of differential transmission lines is provided on one surface of the circuit board, and the voltage supply line is provided on the other surface of the circuit board, which is on a reverse side of the one surface.