Vacuum Release Valve Actuation for Print Media Ejection

Solution Overview

Problem

Inkjet printing systems with stationary imaging and moving media face challenges in accurately ejecting larger print media due to high vacuum pressure, leading to media jams and loss of control, as the mechanical rockers must overcome significant downward force to break the vacuum seal.

Innovation Solution

A rocker actuated vacuum relief valve system that vents vacuum pressure simultaneously with media lifting, reducing the lifting force required by equalizing pressure above and below the media, thereby minimizing the slingshot effect and media jam occurrences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If vacuum pressure is increased to improve media hold-down reliability, then media handling reliability is improved, but ejection force required increases causing rocker deflection and media jams

Engineering Contradiction:

Improvemedia handling reliabilityVSAvoidejection force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The vacuum release valve is actuated in advance of the rockers reaching their full extension position. The valve begins opening when the rockers are approximately 0.5mm from the top of the shuttle plate, and is fully open by the time the rockers reach full extension. This preliminary action of releasing vacuum pressure before complete ejection eliminates the slingshot effect and media jams while maintaining high vacuum pressure during the printing operation for reliable media hold-down.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If mechanical rockers are used to eject media, then media ejection is achieved, but rocker deflection and wear occur due to high lifting forces

Engineering Contradiction:

Improvemedia ejectionVSAvoidrocker durability

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The vacuum release valve is actuated in advance of the rockers reaching their full extension position. The valve begins opening when the rockers are approximately 0.5mm from the top of the shuttle plate, and is fully open by the time the rockers reach full extension. This preliminary action of releasing vacuum pressure before complete ejection eliminates the slingshot effect and media jams while maintaining high vacuum pressure during the printing operation for reliable media hold-down.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If rockers extend fully to lift media, then media ejection is achieved, but slingshot effect causes loss of media control

Engineering Contradiction:

Improvemedia ejectionVSAvoidslingshot effect

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The vacuum release valve is actuated in advance of the rockers reaching their full extension position. The valve begins opening when the rockers are approximately 0.5mm from the top of the shuttle plate, and is fully open by the time the rockers reach full extension. This preliminary action of releasing vacuum pressure before complete ejection eliminates the slingshot effect and media jams while maintaining high vacuum pressure during the printing operation for reliable media hold-down.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system applies preliminary anti-action by releasing the vacuum pressure before the ejection force becomes excessive. The vacuum release valve is triggered when the rockers are approximately 0.5mm from the top of the shuttle plate, creating a counter-action that prevents the harmful slingshot effect from occurring in the first place.

Inventive Principle:

Principle #9Preliminary anti-action

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

The solution effectively reduces the ejection force by a factor of 7, enhancing media control and reducing rocker deflection and wear, while maintaining high hold-down vacuum pressure for reliable media handling.

Implementation Method 1

The print media is often held to the shuttle plate by vacuum pressure

Methodology Applied

Scientific EffectVacuum pressure: Vacuum

Implementation Method 2

venting vacuum pressure simultaneously with media lifting, reducing the lifting force required by equalizing pressure above and below the media

Methodology Applied

Scientific EffectPressure equalization: Pressure Gradient

Data Source

PatentUS7549636B2System and method for ejecting print media from a moveable shuttle

Publication Date: 2009.06.23 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

In one embodiment a media ejection system is disclosed for a printer having a stationary print head and a moveable shuttle configured to hold print media via vacuum pressure while moving the print media past the print head. The media ejection system includes a vacuum release valve, actuable to release vacuum pressure in the shuttle, and a lifter, coupled to the vacuum release valve. The lifter is actuable to mechanically lift the print media from the shuttle, and to simultaneously open the vacuum release valve. In another embodiment, a method for ejecting print media from a moveable shuttle is disclosed. The method includes mechanically lifting the print media from the shuttle and simultaneously substantially equalizing pressure above and below the print media.