Liquid Jetting Head with Dummy Chamber for Accurate Temperature Sensing

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Solution Overview

Problem

Conventional liquid jetting heads with temperature sensors are unable to accurately detect the temperature of the liquid inside flow channels due to the cover plate's thickness and design, which prevents effective temperature sensing.

Innovation Solution

A liquid jetting head design featuring a flow channel substrate with pressure chambers and a dummy pressure chamber, where a vibration plate covers both, and a temperature sensor is positioned on the vibration plate facing the dummy pressure chamber, allowing for accurate temperature detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a cover plate with large thickness is used to cover the pressure chambers, then the structural strength and stability are improved, but the temperature sensor cannot accurately detect the temperature of the liquid inside flow channels

Engineering Contradiction:

Improvestructural strengthVSAvoidtemperature detection accuracy

Core Design Contradiction:

StrengthVSMeasurement precision

Solution Approach 1:

The cover plate is segmented into a vibration plate (thin, flexible portion) and a frame portion (rigid, protective structure). The vibration plate covers only the pressure chambers and has small thickness to enable temperature sensor detection, while the frame portion provides structural strength and covers the temperature sensor, resolving the contradiction between strength and measurement precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the cover plate have different thicknesses and functions: the vibration plate has small thickness for temperature detection capability, while the frame portion has large thickness for structural support. This local differentiation allows both requirements to be satisfied simultaneously.

Inventive Principle:

Principle #3Local quality

2Reliability

If the temperature sensor is arranged on the cover plate, then the sensor is protected from damage, but the sensor cannot accurately detect the temperature of the liquid inside flow channels

Engineering Contradiction:

Improvesensor protectionVSAvoidtemperature detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The vibration plate acts as an intermediary between the temperature sensor and the liquid in flow channels. It transmits thermal information from the liquid to the sensor while allowing the sensor to be positioned on the cover plate for protection. The thin vibration plate enables effective heat transfer for accurate temperature detection.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If the vibration plate has small thickness to enable temperature detection, then the temperature sensor can accurately detect liquid temperature, but the structural strength of the cover plate is reduced

Engineering Contradiction:

Improvetemperature detection accuracyVSAvoidcover plate strength

Core Design Contradiction:

Measurement precisionVSStrength

Solution Approach 1:

The cover plate is divided into a thin vibration plate for temperature detection and a thick frame portion for structural strength. This segmentation allows each portion to be optimized for its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The vibration plate and frame portion are combined into a single integrated cover plate structure. The vibration plate is connected to the frame portion, allowing the thin detection portion to be supported by the strong structural portion, achieving both temperature detection accuracy and structural strength.

Inventive Principle:

Principle #5Merging (Combining)

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 enables precise temperature monitoring of the ink inside the flow channels, improving jet control and reducing the risk of temperature sensor damage during inkjetting.

Implementation Method 1

a piezoelectric body arranged on the second surface of the vibration plate to face the pressure chambers

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

the temperature sensor is arranged on the second surface of the vibration plate at a position facing the dummy pressure chamber

Methodology Applied

Scientific EffectTemperature detection: Thermistor

Data Source

PatentUS10357966B2Liquid jetting head and method for manufacturing the same

Publication Date: 2019.07.23 BROTHER KOGYO KK

AI summary

A liquid jetting head includes a flow channel substrate formed with pressure chambers, an actuator covering the pressure chambers, and a temperature sensor. A dummy pressure chamber is formed in a surface, of the flow channel substrate, in which the pressure chambers are open. The actuator includes: a vibration plate which covers the pressure chambers and the dummy pressure chamber and which has a first surface facing the pressure chambers and a second surface opposite to the first surface, and a piezoelectric body arranged on the second surface of the vibration plate to face the pressure chambers. The temperature sensor is arranged on the second surface of the vibration plate at a position facing the dummy pressure chamber.