Relay Flexible Wiring Board for Inkjet Drive IC Alignment

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Solution Overview

Problem

The increasing number of channels in liquid ejection heads requires finer wiring widths and pitches, making alignment between actuator and flexible printed wiring boards more challenging and costly, particularly when using a common flexible printed wiring board for different configurations.

Innovation Solution

A drive device configuration with a relay flexible printed wiring board that connects actuator and flexible printed wiring boards, featuring conductors with wider widths and lower density than the drive IC's conductors, allowing each actuator to receive drive signals from multiple channels, ensuring high accuracy and compatibility across varying channel counts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the number of channels in liquid ejection heads is increased, then the functionality and coverage of the device is improved, but the wiring width and pitch become finer making alignment more difficult

Engineering Contradiction:
Improvenumber of channelsVSAvoidalignment accuracy
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

A relay flexible printed wiring board is introduced as an intermediary component between the actuator board and the drive IC flexible printed wiring board. This relay board has conductors with larger widths and lower density, serving as a buffer that connects the fine-pitch drive IC conductors to the coarser actuator board connections, thereby reducing alignment difficulty while maintaining support for high channel counts

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The connection system is divided into three separate boards: an actuator board, a relay flexible printed wiring board, and a drive IC flexible printed wiring board. This segmentation allows each component to be optimized independently - the drive IC board can have fine-pitch conductors for high channel density while the actuator board maintains larger connection pads, with the relay board bridging the two

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If a common flexible printed wiring board is used for different liquid ejection head configurations, then development cost is reduced, but alignment accuracy becomes more challenging due to varying channel counts

Engineering Contradiction:
Improvedevelopment costVSAvoidalignment accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The relay flexible printed wiring board is designed as a universal component that can interface with different actuator board configurations having varying numbers of channels. The relay board maintains a consistent structure with the drive IC board while accommodating different channel counts through its conductor arrangement, allowing the same relay board to be used across multiple device variants

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The relay board acts as an adapter layer that decouples the fixed drive IC board from variable actuator board configurations. This intermediary allows a single drive IC board design to support multiple channel counts by interfacing with differently-configured actuator boards through the standardized relay board connection interface

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4140745B1Inkjet head comprising a drive device
Publication Date: 2024.07.31 RISO TECH CORP
  • EP4140745B1 patent drawingFigure 1
  • EP4140745B1 patent drawingFigure 2
  • EP4140745B1 patent drawingFigure 3

AI summary

According to one embodiment, a drive device in which conductors from a plurality of elements arranged in terminal parts on respective boards and conductors from a plurality of channels of a drive IC are connected with a high accuracy is provided. The drive device according to an embodiment includes a first board (22), a second board (4), and a relay board (3). On the first board (22), a plurality of elements (6) are arranged, and a plurality of first conductors (64) that respectively send a drive signal to the plurality of elements are arranged in a terminal part (20). On the second board (4), a drive IC (41) that drives the plurality of elements is mounted, and second conductors (43) from a plurality of channels of the drive IC are arranged in a terminal part (40). On the relay board (3), a plurality of third conductors (32) are formed from a terminal part (30) to be connected to the first board (22) to a terminal part (31) to be connected to the second board (4), and the third conductors (32) each having a width larger than a pitch of the second conductors (43) are arranged at a lower density than the second conductors (43) in the terminal part (31) connected to the second board (4), so that each of the first conductors (64) that sends a drive signal to the elements (6) is connected to each of the second conductors (43) from two or more of the channels of the drive IC (41).