Printhead IC Temperature Sensor Drive Pulse Adjustment

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Solution Overview

Problem

Inkjet printers with pagewidth printheads face challenges in maintaining uniform drop ejection characteristics due to temperature variations along the nozzle array, leading to visible artifacts in printed pages, as ink viscosity is temperature-dependent and affects nozzle performance.

Innovation Solution

Incorporating temperature sensors into the printhead ICs to adjust drive pulse profiles based on temperature readings, with the option to deactivate sensors once the operating temperature is reached to reduce power consumption and noise, and using open actuator test circuitry to identify defective nozzles and adjust print data accordingly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If temperature sensors are continuously activated in printhead ICs, then temperature compensation for uniform drop ejection is improved, but power consumption and electronic noise increase

Engineering Contradiction:

Improveuniform drop ejectionVSAvoidpower consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The temperature sensor is activated periodically rather than continuously. The controller activates the temperature sensor at specific intervals to obtain temperature readings, then uses these readings to adjust drive pulse parameters. This periodic activation maintains temperature compensation capability while significantly reducing power consumption compared to continuous operation.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts the activation state of the temperature sensor based on operational conditions. The controller determines when temperature readings are necessary and activates the sensor only during those periods, making the system adaptive rather than static. This dynamic approach optimizes the balance between compensation accuracy and power consumption.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If temperature sensors are continuously activated in printhead ICs, then temperature compensation for uniform drop ejection is improved, but electronic noise in circuits increases

Engineering Contradiction:

Improveuniform drop ejectionVSAvoidelectronic noise

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

By activating the temperature sensor periodically rather than continuously, the system reduces the total time the sensor circuit is active. This reduced active time directly lowers the generation of electronic noise in the circuit, while still obtaining sufficient temperature data points to maintain effective compensation for uniform drop ejection.

Inventive Principle:

Principle #19Periodic action

3Reliability

If drive pulse duration is extended to de-clog nozzles, then nozzle reliability is improved, but ink droplet placement precision deteriorates

Engineering Contradiction:

Improvenozzle functionalityVSAvoiddroplet placement

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The controller applies different drive pulse durations to different nozzles based on their individual needs. Nozzles that require de-clogging receive extended duration pulses, while nozzles functioning normally receive standard duration pulses. This localized differentiation allows the system to maintain overall droplet placement precision while providing targeted de-clogging assistance where needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system changes the drive pulse parameter (duration) dynamically based on nozzle condition and temperature. By adjusting the pulse duration parameter according to real-time temperature readings and nozzle performance feedback, the system optimizes both de-clogging effectiveness and droplet placement accuracy without compromising either aspect.

Inventive Principle:

Principle #35Parameter changes

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 solution ensures uniform drop ejection across the pagewidth printhead by compensating for temperature-induced viscosity changes, improving print quality and extending printhead operational life by identifying and managing defective nozzles.

Implementation Method 1

a temperature sensor connected to the drive circuitry to adjust the drive pulse profile in response to the temperature sensor output

Methodology Applied

Scientific EffectTemperature sensing:

Implementation Method 2

Each nozzle is a MEMS (micro electromechanical systems) device driven by associated drive circuitry formed on the same silicon wafer substrate

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 3

the ink viscosity is temperature dependent and therefore the ink viscosity can also vary along the length of the nozzle array

Methodology Applied

Scientific EffectTemperature-dependent viscosity:

Data Source

PatentUS7997673B2Printhead IC with temperature based de-clog ejection

Publication Date: 2011.08.16 MEMJET TECH LTD

AI summary

A printhead IC is provided having an ejection nozzle, drive circuitry for generating drive signals for driving the ejection nozzle, and a temperature sensor connected to the drive circuitry. The drive circuitry adjusts the drive signals in response to output of the temperature sensor so as to generate the drive signals as print signals and de-clog signals. The de-clog signals have a longer duration than the print signals.