WO2019151971A1

WO2019151971A1 - Printing system

Info

Publication number: WO2019151971A1
Application number: PCT/US2018/015814
Authority: WO
Inventors: Kevin Dooley; SeeMun PHOONG; Martin Purcell
Original assignee: Hewlett Packard Development Co LP
Current assignee: Hewlett Packard Development Co LP
Priority date: 2018-01-30
Filing date: 2018-01-30
Publication date: 2019-08-08
Anticipated expiration: 2020-07-30

Abstract

A printing system is described, which comprises a first print agent supply, comprising a capillary material disposed therein to hold a volume of print agent, the first print agent supply in fluid communication with a plurality of print agent ejection elements of a printhead. The printing system also comprises a second print agent supply, to hold a volume of print agent, upstream of the first print agent supply. The printing system also comprises a fluid communication channel to fluidically couple the second print agent supply to the first print agent supply, wherein the fluid communication channel comprises a capillary material therein.

Description

PRINTING SYSTEM

BACKGROUND

Printing systems for use in a continuous print agent supply environment comprise a print head assembly (PHA), a reservoir containing a print agent and a tube to provide fluid communication between the reservoir and the PHA. After installation, but before first use, the tube that connects the PHA and the reservoir should be primed with print agent. The priming occurs by expelling print agent from the PHA into a receptacle arranged to receive ejected print agent. As print agent is expelled from the PHA a negative back-pressure is created in the PHA, which draws print agent through the tube from the reservoir. However, a volume of print agent is irrecoverably lost from a reservoir of the PHA for the priming process, thereby effectively reducing the lifespan of the PHA.

Further, if the PHA is de-coupled from the tube, for example, for maintenance, then priming would need to be carried out again when the PHA and tube are reconnected. This may mean that a further volume of print agent is lost, effectively reducing the lifespan of the PHA yet further.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a printing system of the present disclosure.

DETAILED DESCRIPTION

Implementations discussed herein include a printing system for a continuous ink supply system. The printing system may also be employed in a 3D print environment, i.e. where the print agent may be of a type other than ink.

FIG. 1 is an illustration of a printing system 10 of the present disclosure, which comprises a print head assembly 12, comprising a printhead 14 and a first print agent supply 16, and a second print agent supply 18. The first print agent supply 16 comprises, in the illustrated example, a four compartment foam storage structure defined by three partition walls 20, 22 and 24, which extend vertically upward from a bottom wall section 26 and which are surrounded by outer side walls 28 and 30. The outer side walls 28 and 30 include offset flange portions 32 and 34, which rest on inwardly extending sections 36 and 38 of a mating outer housing wall 40. A top cover plate 42 is received at the top of the outer walls 28 and 30 for providing a top closure for the print head assembly 12. The bottom wall section 26 comprises, on a downwardly facing surface thereof, the printhead 14.

In the illustrated example, the four ink storage compartments within the first print agent supply 16 are for storing yellow ink, magenta ink, cyan ink, and black ink respectively (identified by the letters Y, M, C, and K respectively). Each compartment comprises a capillary material (e.g. a foam) to provide a porous storage medium for the various coloured inks. In other words, the first print agent supply 16 can hold a volume of print agent(s) (e.g. ink(s)) and each storage compartment comprises foam therein to hold a volume of print agent of a particular type.

Each of the storage compartments within the first print agent supply 16 is connected respectively by way of a port 44, 46, 48, 50 located in a wall of each of these four compartments to fluid communication channels 52, 54, 56 and 58 respectively. These fluid communication channels can, in some examples, comprise flexible tubes. The fluid communication channels can be connected as shown through a common fluid communication channel support and spacer member 60, which serves to maintain the four fluid communication channels 52, 54, 56 and 58 in place and separated one from another as they extend respectively to four ink supply sections 62, 64, 66 and 68 within second print agent supply 18. Each of these ink supply sections 62, 64, 66, and 68 can receive a replaceable ink bottle 70, 72, 74 and 76, respectively and each ink bottle is provided with a rupturable seal 80, which is opened when brought into contact with a central upstanding member 82 of each supply section 62, 64, 66 and 68. When the seal 80 is broken, ink in the bottle 70, for example, will flow into section 62, which will fill up with cyan coloured ink, and similar action will occur for the other colours (and black and/or clear) in the other supply sections 64, 66 and 68 as indicated.

When the printhead 14 is operational, a pumping action of the printhead 14 induces a negative pressure in the capillary material in the storage compartments, which will cause the ink from the ink supply sections 62, 64, 66 and 68 to be drawn through their associated fluid communication channels 50, 52, 54 and 56.

As ink is ejected from the storage compartments and out of the printhead 14 during a print operation, a negative head in each of the storage compartments will increase and will produce, by capillary action, a pulling of the print agent from the supply vessels 62, 64, 66 and 68 and through the various fluid communication channels 52, 54, 56 and 58, respectively, and into the storage compartments of the first print agent supply 16. This action will continue until such time that the ink level in each of the four storage compartments is brought back up to a level such that the negative pressure at the printhead 14 is less than the static head difference between the printhead 38 and a liquid level in each of the reservoirs.

In the printing system 10 of the present disclosure, each of the fluid communication channels 52, 54, 56 and 58 comprises a capillary material therein. The capillary material is denoted by way of reference numeral 84 in the figure. The capillary material 84 comprises a material, which can comprise at least one of a fibre, foam or similar material. The material is porous and, optionally, a polymer material. Examples of materials within the capillary material include PET fibres, Polyester, Polypropylene, and/or an EPDM/PET yarn. In some example implementations, the capillary material can be sheathed in a wrap material.

Different types of capillary material 84 can be employed depending upon the print agent type to be communicated from the second print agent supply 18 to the first print agent supply 16. For example, pore size, pore volume, pore spacing and/or pore density of a capillary material for conveying a print agent of a first type may differ from those of a capillary material for conveying a print agent of a second type. In an example implementation where a print agent comprises ink, a first colour ink may be of a different viscosity to that of a second colour ink. Therefore, the capillary material in the fluid communication channel for the first colour ink may be different to the capillary material in the fluid communication channel for the second colour ink.

In a printing system employing capillary material in fluid communication channels in the manner described above, when the fluid communication channels are coupled to their associated sections of the second print agent supply, contact of print agents in the sections of the second print agent supply with the capillary material will result in the print agents being drawn into their associated fluid communication channels. The nature of the capillary material causes the print agents to be drawn through the fluid communication channels (i.e. a“wicking” action) to the first print agent supply 16. Thus, the printing system is effectively “primed” without the need for ejecting ink. Therefore ink loss in a priming process may be inhibited, because no priming process may be required.

In examples of previous printing systems, between around 1.5g and around 2.5g of ink is lost from a print head assembly during priming. The rate of ink loss per month from the print head assembly depending on environmental conditions is between around 0.1g and around 0.06g per month. Table 1 below shows where ink is available to use and where losses occur in an example previous printing system. Table 1 : Availability of ink in a print head assembly

Based on an ink loss per month of between around 0.1 g and around 0.06g, expected life of ink in the print head assembly of the example previous printing system is:

• Black - between around:

- 126.05 months (i.e. 12.605/0.1) « 10.5 years; and around

- 210.08 months (i.e. 12.605/0.06) « 17.5 years.

• Yellow - between around:

- 22.40 months (i.e. 2.240/0.1) « 1.9 years; and around

- 37.33 months (i.e. 2.240/0.06) « 3.1 years.

• Cyan - between around:

- 22.40 months (i.e. 2.240/0.1) « 1.9 years; and around

- 37.33 months (i.e. 2.240/0.06) « 3.1 years.

• Magenta - between around:

- 29.20 months (i.e. 2.920/0.1) « 2.4 years; and around

- 48.67 months (i.e. 2.920/0.06) « 4.1 years.

By reducing, or inhibiting, the loss of ink through priming (by eliminating the need for priming), the expected life of ink in the print head assembly could be extended, through use of a printing system according to the present disclosure, as follows:

• Black - between around:

- 144.65 months (i.e. (12.605 + 1.860)/0.1) « 12.1 years; and around

- 241.08 months (i.e. (12.605 + 1 860)/0.06) « 20.1 years.

• Yellow - between around:

- 38.60 months (i.e. (2.240 + 1.620)/0.1) « 3.2 years; and around

- 64.33 months (i.e. (2.240 + 1 620)/0.06) « 5.4 years. Cyan - between around:

- 38.60 months (i.e. (2.240 + 1.620)/0.1) « 3.2 years; and around

- 64.33 months (i.e. (2.240 + 1.620)/0.06) ~ 5.4 years.

Magenta - between around:

- 45.40 months (i.e. (2.920 + 1.620)/0.1) « 3.8 years; and around

- 75.67 months (i.e. (2.920 + 1.620)70.06) ^« 6.3 years.

In an example implementation of the present disclosure, a volume of ink can be introduced to the capillary material allowing it to prime over time, i.e. the fluid communication channels could be pre-primed prior to installation, or first use, of the printing system. This may allow the system to become fully primed over a period of time, e.g. before an end-user receives the printer.

The printing system according to the present disclosure may allow the life of a print head assembly to be extended, because there is no ink loss from the due to priming (i.e. no priming may be needed).

The printing system according to the present disclosure may allow a print head assembly to be de-coupled from the printing system (e.g. for maintenance) without requiring additional features to prevent print agent leaking from the system and/or to prevent de priming. This is because the capillary material in the fluid communication channel can retain print agent regardless of the state of the print head assembly (i.e. coupled or uncoupled).

Claims

1. A printing system comprising:

a first print agent supply, comprising a capillary material disposed therein to hold a volume of print agent, said first print agent supply in fluid communication with a plurality of print agent ejection elements of a printhead;

a second print agent supply, to hold a volume of print agent, upstream of said first print agent supply; and

a fluid communication channel to fluidically couple said second print agent supply to said first print agent supply, wherein said fluid communication channel comprises a capillary material therein.

2. A printing system according to claim 1 , wherein said capillary material of said fluid communication channel comprises a fibrous material.

3. A printing system according to claim 1 or 2, wherein said capillary material of said fluid communication channel comprises a porous material.

4. A printing system according to any one of the preceding claims, wherein said capillary material of said fluid communication channel comprises a foam material.

5. A printing system according to any one of the preceding claims, wherein said capillary material of said fluid communication channel comprises a polymer material.

6. A printing system according to claim 5, wherein said capillary material of said fluid communication channel comprises polyester.

7. A printing system according to any one of the preceding claims, comprising a plurality of print agent types, wherein said first print agent supply comprises a corresponding capillary material for each print agent type, said second print agent supply comprises a corresponding volume for each print agent type, and said fluid communication channel comprises a fluid communication channel corresponding to each print agent type.

8. A printing system according to claim 7, wherein a first capillary material in a fluid communication channel for a first print agent type differs from a second capillary material in a fluid communication channel for a second print agent type.

9. A printing system according to claim 8, wherein said first capillary material comprises a different density material to a material of said second capillary material.

10. A printing system according to claim 8 or 9, wherein said first capillary material comprises a material with different pore volume to a material of said second capillary material.

11. A printing system according to any one of claims 8 to 10, wherein said first capillary material comprises a material with different pore spacing to a material of said second capillary material.

12. A printing system according to any one of the preceding claims, wherein said print agent comprises ink.

13. A printing system according to any one of the preceding claims, wherein said capillary material of said fluid communication channel is primed with a quantity of print agent that extends over a portion of said fluid communication channel from said second print agent supply.

14. A fluid communication channel to fluidically couple a first print agent supply to a second print agent supply, comprising:

a first end to couple to a port of a first print agent supply, which is fluidically coupleable with a plurality of print agent ejection elements of a printhead; and a second end to couple to a port of a second print agent supply;

wherein said fluid communication channel comprises a capillary material therein.

15. A fluid communication channel according to claim 14, wherein said capillary material of said fluid communication channel comprises at least one of: a fibrous material; a porous material; a foam material; and a polymer material.