Head Driving Device Segmentation for Ink Droplet Consistency

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Solution Overview

Problem

Conventional image forming apparatuses with liquid ejection recording systems face challenges in achieving high-quality images due to manufacturing variations in nozzle shape, ink channel structure, and piezoelectric element characteristics, leading to inconsistent ink droplet ejection and landing positions, which increases the size and power consumption of drive waveform generating circuits.

Innovation Solution

A head driving device with multiple drive waveform generating units, each tailored to individual nozzles to correct variations in ink droplet amount and landing position, using charge/discharge signal generating units and driver units to optimize drive waveforms for precise ink ejection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a common drive waveform generating circuit is used for all piezoelectric elements, then the device complexity and power consumption are reduced, but the manufacturing precision of ink droplet ejection and landing position deteriorates due to variations in nozzle and piezoelectric element characteristics

Engineering Contradiction:
Improvedrive waveform generating circuit sizeVSAvoidink droplet ejection consistency
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent divides the single common drive waveform generating circuit into multiple independent drive waveform generating units, with each unit dedicated to driving a specific piezoelectric element. This segmentation allows each unit to generate optimized drive waveforms that compensate for individual variations in nozzle characteristics and piezoelectric element properties, thereby improving ink droplet ejection consistency while maintaining manageable device complexity through modular architecture

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements local quality by providing customized drive waveform generating units for each piezoelectric element, allowing each unit to be optimized for the specific characteristics of its corresponding nozzle and piezoelectric element. This enables individual compensation for manufacturing variations, improving overall manufacturing precision without requiring a completely custom solution for each element

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If individual drive waveform generating units are provided for each piezoelectric element, then the manufacturing precision of ink droplet ejection and landing position is improved, but the device complexity and power consumption increase

Engineering Contradiction:
Improvelanding position accuracyVSAvoidnumber of drive waveform generating units
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent segments the drive waveform generation function into separate units for each piezoelectric element, which improves landing position accuracy by allowing individual optimization. The modular nature of this segmentation means that while there are multiple units, each unit is a simplified version of the overall system, making the increase in device complexity manageable and scalable

Inventive Principle:
Principle #1Segmentation

3Ease of operation

If high-voltage power MOSFET switching elements are integrated with control units, then the ease of operation is improved, but the device complexity increases due to the large size of integrated switching elements

Engineering Contradiction:
Improvecontrol signal integrationVSAvoidswitching element size
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent separates the switching elements from the control units, with switching elements being externally mounted and control units integrated with the piezoelectric elements. This segmentation reduces the size of integrated components while maintaining operational ease, as the externally mounted switching elements can be optimized independently for their specific functions without increasing the footprint of the integrated control units

Inventive Principle:
Principle #1Segmentation

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 allows for accurate correction of ink droplet variations and landing positions, reducing image quality issues while minimizing the size and power consumption of the drive circuitry, enabling high-quality image formation.

Implementation Method 1

A piezoelectric type recording head uses a piezoelectric element (for example, a piezo element) as the pressure generating means, and causes a diaphragm forming a wall surface of the ink channel to slightly vibrate with the aid of the piezoelectric element in order to change the inner capacity of the ink channel to eject ink droplets

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP2944470B1Head driving device, recording head unit, and image forming apparatus
Publication Date: 2019.09.11 RICOH CO LTD
  • EP2944470B1 patent drawingFigure 1~2
  • EP2944470B1 patent drawingFigure 3A~3B
  • EP2944470B1 patent drawingFigure 4

AI summary

The invention is concerning a head driving device (30) that drives a recording head (3) including a plurality of nozzles (4) and a plurality of pressure generating elements (5) corresponding to the respective nozzles (4). The head driving device (30) comprises: a plurality of drive waveform generating units (33, 33A) corresponding to the respective pressure generating elements (5), wherein the drive waveform generating units (33, 33A) drive the respective pressure generating elements (5) on the basis of pieces of drive waveform information that are set for the respective nozzles (4) so as to approximately equalize ejection characteristics of droplets ejected from the nozzles (4).