Page Wide Array Print Head Servicing via Movable Carriage

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Solution Overview

Problem

Page-wide-array (PWA) print heads are prone to clogging due to uneven nozzle exercise, leading to drying ink issues and contamination, which existing servicing methods cannot effectively address without requiring the print head to be removed and serviced, resulting in increased printer footprint and potential mechanical wear.

Innovation Solution

A movable carriage with integrated service components and sensors is used to perform maintenance on the PWA print head while it remains in place, allowing for sequential cleaning and inspection of nozzles without moving the print head bar, thus minimizing printer footprint and preventing alignment issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of repair

If the print head is removed for cleaning and servicing, then cleaning effectiveness is improved, but mechanical wear increases and alignment precision deteriorates

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidalignment precision

Core Design Contradiction:

Ease of repairVSManufacturing precision

Solution Approach 1:

The print head performs self-cleaning through the integrated service station located at one end of the print head bar. The service components (wipers, scrapers, cleaning fluids) are built into the print head assembly itself, allowing continuous cleaning during operation without removal. This resolves the contradiction by enabling effective cleaning (improving ease of repair) while the print head remains fixed and aligned (maintaining manufacturing precision).

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent introduces dynamic cleaning elements that move relative to the print head nozzles. Wipers and scrapers are positioned to contact and clean the nozzle surfaces during print head operation. This dynamic cleaning mechanism provides continuous maintenance (improving ease of repair) without requiring print head removal or realignment (maintaining manufacturing precision).

Inventive Principle:

Principle #15Dynamics

2Ease of repair

If the print head bar is moved to a service location, then cleaning access is improved, but printer footprint increases and mechanical stability deteriorates

Engineering Contradiction:

Improvecleaning accessVSAvoidprinter footprint

Core Design Contradiction:

Ease of repairVSArea of stationary object

Solution Approach 1:

The service functionality is segmented and distributed along the print head bar, with the service station integrated at one end. This segmentation allows cleaning operations to be performed in place without moving the entire print head bar to a separate service location. The solution improves cleaning access (ease of repair) while keeping the printer footprint compact (maintaining area of stationary object).

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The service station at one end of the print head bar serves multiple functions: cleaning nozzles, replenishing ink, and monitoring print head condition. This multi-functional integration eliminates the need for separate service locations or moving the print head bar, thereby improving cleaning access (ease of repair) without increasing printer footprint (maintaining area of stationary object).

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of repair

If the print head bar is moved to a service location, then cleaning access is improved, but alignment precision deteriorates

Engineering Contradiction:

Improvecleaning accessVSAvoidalignment precision

Core Design Contradiction:

Ease of repairVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Inventive Principle:

Principle #15Dynamics

4Ease of repair

If repeated insertion and removal of the print head bar is performed, then cleaning is achieved, but mechanical durability deteriorates

Engineering Contradiction:

Improvecleaning capabilityVSAvoidmechanical durability

Core Design Contradiction:

Ease of repairVSDuration of action of stationary object

Solution Approach 1:

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8157348B2Print head servicing for a page wide array printer

Publication Date: 2012.04.17 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

A page wide array printer comprises a print head bar which carries an array of print nozzles, and which is static during a printing operation. A carriage has print head service elements. The print head bar is movable perpendicularly to the plane of the print medium beneath the print head, between a lowered print position and a raised service position. The carriage is moveable along the print head to perform a service operation when the print head is in the raised position.