WO2009049348A1 - Printer with reservoir headspace pressure control - Google Patents
Printer with reservoir headspace pressure control Download PDFInfo
- Publication number
- WO2009049348A1 WO2009049348A1 PCT/AU2007/001563 AU2007001563W WO2009049348A1 WO 2009049348 A1 WO2009049348 A1 WO 2009049348A1 AU 2007001563 W AU2007001563 W AU 2007001563W WO 2009049348 A1 WO2009049348 A1 WO 2009049348A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- ink
- printhead
- inkjet printer
- headspace
- printer according
- Prior art date
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/17—Ink jet characterised by ink handling
- B41J2/175—Ink supply systems ; Circuit parts therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/17—Ink jet characterised by ink handling
- B41J2/175—Ink supply systems ; Circuit parts therefor
- B41J2/17503—Ink cartridges
- B41J2/17506—Refilling of the cartridge
- B41J2/17509—Whilst mounted in the printer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/17—Ink jet characterised by ink handling
- B41J2/175—Ink supply systems ; Circuit parts therefor
- B41J2/17503—Ink cartridges
- B41J2/17556—Means for regulating the pressure in the cartridge
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/17—Ink jet characterised by ink handling
- B41J2/175—Ink supply systems ; Circuit parts therefor
- B41J2/17596—Ink pumps, ink valves
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/17—Ink jet characterised by ink handling
- B41J2/18—Ink recirculation systems
- B41J2/185—Ink-collectors; Ink-catchers
Definitions
- the present invention relates to printers and in particular the fluidic architecture of inkjet printers.
- InkJet printing is a popular and versatile form of print imaging.
- the Assignee has developed printers that eject ink through MEMS printhead ICs. These printhead ICs
- integrated circuits are formed using lithographic etching and deposition techniques used for semiconductor fabrication.
- micro-scale nozzle structures in MEMS printhead ICs allow a high nozzle density (nozzles per unit of IC surface area), high print resolutions, low power consumption, self cooling operation and therefore high print speeds.
- Such printheads are described in detail in USSN 10/160273 (Our Docket No.MJ40US) filed June 4, 2002 and USSN 10/728804 (Our Docket No MTBOlUS) filed on December 8, 2003 to the present Assignee. The disclosures of these documents are incorporated herein by reference.
- the small nozzle structures and high nozzle densities can create difficulties with color mixing between nozzles of different color.
- the separate fluidic lines for each ink color can undergo slight pressure changes relative to each other. Different rates of heating and outgassing in different ink lines will generate a slight pressure differential. If paper dust or ink residue on the nozzle face extends between nozzles of the different ink lines, the dust or residual ink can forge a fluid connection between the two ink lines.
- the ink lines try to equalize the pressure difference between them and this drives an ink from the higher pressure line to the lower pressure line. If left unchecked, the ink contamination in the lower pressure ink line can extend to the ink tank.
- the contaminated ink supply is irretrievable and needs replacement before the ink lines are flushed through to the nozzles.
- the ink tanks can be isolated from the printhead by a shut off valve upstream of the printhead. This protects the tanks from contamination during standby, but there is a risk that the tank and the printhead will generate a pressure difference during the standby period. If this happens, the sudden pressure equalization causes a pulse through the ink line which floods the nozzle plate.
- the present invention provides an inkjet printer comprising: a printhead for printing onto a media substrate; a reservoir for containing a quantity of ink, the reservoir having a lower portion for holding ink and an upper portion defining a headspace of air above the ink; a fluid connection extending between the printhead and the reservoir; and, a pump for drawing air from the headspace into atmosphere.
- the invention uses a fluidic system that controls the air pressure in the headspace of an ink reservoir to control the hydrostatic pressure of the ink at the key points along the ink line.
- Controlling the ink pressure in one of the ink reservoirs can maintain a more consistent negative pressure (i.e. a hydroststatic pressure less than atmospheric) at the printhead nozzles.
- the negative pressure at the printhead nozzles prevents, or at least reduces color mixing by ensuring that the ink meniscus at each nozzle is drawn inwards. An inwardly drawn meniscus significantly reduces the chance that paper dust or residual ink can establish a fluid connection between nozzles of different color.
- Drawing air from the headspace in the sump helps to equalize the pressure in the different ink lines as the sump headspace is common to all the color channels.
- the air pressure in each ink tank is equal and so the hydrostatic pressure of the ink at the nozzles will only vary by the variations in the ink levels of the ink tanks. In a normal usage profile, the ink levels remain roughly the same for each ink tank.
- the tanks can have a wide and squat shape to reduce the change in hydrostatic pressure from full to empty. With equal pressures (or at least very nearly equal pressures) in each ink line, there is no pressure differential to drive a color mixing process other than diffusion. As the fluid connection across the nozzle is so small, mixing by diffusion is negligible.
- the reservoir is a sump that collects waste ink drained from the printhead.
- the reservoir has a vent for venting the headspace to atmosphere, and for allowing a throttled flow of air into the headspace as the pump is drawing air out of the headspace.
- the vent has a filter for removing particulate contaminants from the throttled air flow into the headspace.
- the printing further comprises an upstream valve positioned upstream of the printhead.
- the printer further comprises a downstream valve positioned downstream of the printhead.
- the pump is reversible such that it can increase the air pressure in the headspace and force ink towards the printhead.
- the pump is used to prime the printhead.
- the pump is used to purge ink from the nozzles and flood the printhead.
- the printhead has a distribution manifold and a plurality of printhead integrated circuits mounted to the distribution manifold such that priming the distribution manifold with ink also primes the printhead integrated circuits.
- the printer further comprises a maintenance station having a capper and blotter for the printhead integrated circuits.
- the pump is in fluid communication with the maintenance station and the sump such that ink collected by the maintenance station can be transferred to the sump by running the pump in one direction and air drawn from the headspace by running the pump in the other direction.
- the printhead is provided as a user removable and replaceable cartridge which is fluidly detachable from the printer via the upstream and the downstream valves.
- Figure 1 shows a schematic diagram of a printer fiuidic system according to the present invention.
- Figure 2 shows a schematic diagram of another printer fiuidic system according to the present invention.
- the fluidic system shown in Figure 1 has a printhead 2 supplied with ink 14 from an ink tank 8 via an upstream ink line 20. Waste ink from the printhead 2 drains to a sump 28 through downstream ink line 24.
- the upstream ink line 20 has a shut off valve 18 and the downstream ink line has shut off valve 26. These valves can be used for priming and purging ink (discussed below) and as detachable fluid connections is the printhead is provided in the form of user removable and replaceable cartridge such as that shown in the above referenced
- the printhead has a maintenance station 22 for capping and blotting the nozzles.
- a drain line 16 connects the maintenance station 22 to the sump 28.
- the printhead 2 is an assembly of an ink distribution manifold 4 on which a series of printhead integrated circuits (ICs) 6 are mounted.
- the printhead ICs 6 define the nozzle arrays which eject the ink to the media substrate.
- the nozzles are MEMS devices which can be thermally actuated such as those described in USSN 11/482953 (Our Docket No. MTDOOlUS) filed on July 10, 2006 or mechanically actuated such as those disclosed in USSN 10/160273 (Our Docket No.MJ40US) filed June 4, 2002.
- the ink distribution manifold 4 is an LCP molding with a system of large channels feeding a network of smaller channels to supply the ink to many points along the length of each printhead IC 6.
- An embodiment of the distribution manifold 4 and the printhead ICs 6 is disclosed in detail in the USSN 11/688863 (Our docket No. RREOOlUS) filed March 21, 2007 reference listed above. This document also details the manner in which the printhead is primed with ink or, if necessary, purged of ink to correct any cross channel color contamination and/or bubble removal.
- the air pump 30 draws air from the headspace 32 in the tank 8.
- the air pressure in the headspace drops and air is drawn back into the headspace 32 through the filtered vent 40.
- the air constriction from the vent 40 is carefully controlled to create a predetermined negative air pressure.
- the tubing 38 fluidly connects the headspaces 34 and 36 in tanks 10 and 12 such that all the headspaces are at the same air pressure.
- Tanks 10 and 12 can have their own vents to atmosphere (not shown) but the system will operate with a single vent.
- the hydrostatic pressure in the ink is very early equal.
- the hydrostatic pressure of the ink at the nozzles will only vary by the variations in the ink levels of the ink tanks. Normal usage is designed to keep the ink levels roughly the same in each ink tank. To further minimize variations, the tanks can have a wide and squat shape to reduce the change in hydrostatic pressure from full to empty. With equal pressures (or at least very nearly equal pressures) in each ink line, there is no pressure differential to drive a color mixing process other than diffusion. As the fluid connection across the nozzle is so small, mixing by diffusion is negligible.
- the pump 30 is reversible so it can be used to pressurize the headspaces 32, 34 and 36 in order to prime the printhead 2 or purge ink through the printhead ICs 6. Priming requires the upstream and downstream shut off valves 18 and 26 to be open. Ink from the tanks 8, 10 and 12 is forced down the upstream ink line 20, through the distribution manifold 4 and into the sump 28 via the downstream ink line 24. The printhead ICs 6 prime by capillary action from the ink in the distribution manifold.
- the down stream valve 26 is closed as the pump 30 pressurizes the headspace 32. Ink is forced from the nozzles and the resulting flood on the nozzle plate is cleared with the maintenance station 22.
- the pump 30 operates during a power up standby mode.
- the printer is still plugged in and connected to a power supply.
- the shut off valve 18 and 26 are closed to isolate the printhead and prevent mixing.
- the pump 30 can be used to ready the printhead by priming or purging (if necessary) as discussed above.
- FIG. 2 shows the pump 30 operating on the headspace 32 of the sump 28 instead of the ink tank 8. Again, a single ink line is shown but the color printer will have several color lines all draining to the same sump 28. As long as all the down stream ink lines 24 for each color connect to the sump headspace, a single pump can be used to change the hydrostatic pressures in the ink at the nozzles. With the pump 30 connected to the sump 28, the upstream shut off valve 18 is closed during power down standby. The negative air pressure in the headspace 32 draws on the column of ink hanging from the printhead 2. This ensures that a sufficiently negative pressure is maintained at the nozzles. More importantly, the negative pressure in the nozzles of each color is the same. As discussed above, this removes the mechanism that drives the color mixing process.
- the pump 30 is marginally more complex in that it needs to be able to handle an ink/air mixture. It is in the drain line 16 from the maintenance assembly 22 to the sump 28 to assist the transfer of blotted ink to the sump 28 but needs to be able to draw air from the headspace 32 or from atmosphere through the filter 42.
- priming requires the upstream valve 18 to be open and the pump 30 to create a low pressure in the sump 28 to draw the ink from the tank 8 down the upstream ink line 20, through the distribution manifold 4 and into the downstream ink line 24.
- the printhead ICs 6 prime by capillarity.
- the upstream valve 18 is closed and the pump 30 creates a positive pressure in the headspace 32 to force the ink in the down stream ink line 24 and the distribution manifold 4 to flood the printhead ICs 6.
Abstract
An inkjet printer that has a printhead (6) for printing onto a media substrate, and a reservoir, either a waste collection (28) or ink cartridges (8) containing a quantity of ink, the reservoir having a lower portion (14) for holding ink and an upper portion (32) defining a headspace of air above the ink. A fluid connection (20,16,24) extends between the printhead and reservoir whether it be waste tank or cartridge. A pump (30) draws air form the headspace to lower its air pressure and thereby controls the hydrostatic pressure of the ink at the printhead. Air vent (40) vents to atmosphere.
Description
PRINTER WITH RESERVOIR HEADSPACE PRESSURE CONTROL
FIELD OF THE INVENTION The present invention relates to printers and in particular the fluidic architecture of inkjet printers.
BACKGROUND OF THE INVENTION
InkJet printing is a popular and versatile form of print imaging. The Assignee has developed printers that eject ink through MEMS printhead ICs. These printhead ICs
(integrated circuits) are formed using lithographic etching and deposition techniques used for semiconductor fabrication.
The micro-scale nozzle structures in MEMS printhead ICs allow a high nozzle density (nozzles per unit of IC surface area), high print resolutions, low power consumption, self cooling operation and therefore high print speeds. Such printheads are described in detail in USSN 10/160273 (Our Docket No.MJ40US) filed June 4, 2002 and USSN 10/728804 (Our Docket No MTBOlUS) filed on December 8, 2003 to the present Assignee. The disclosures of these documents are incorporated herein by reference.
The small nozzle structures and high nozzle densities can create difficulties with color mixing between nozzles of different color. During periods of prolonged inactivity (or 'standby mode') the separate fluidic lines for each ink color can undergo slight pressure changes relative to each other. Different rates of heating and outgassing in different ink lines will generate a slight pressure differential. If paper dust or ink residue on the nozzle face extends between nozzles of the different ink lines, the dust or residual ink can forge a fluid connection between the two ink lines. The ink lines try to equalize the pressure difference between them and this drives an ink from the higher pressure line to the lower pressure line. If left unchecked, the ink contamination in the lower pressure ink line can extend to the ink tank. In this case, the contaminated ink supply is irretrievable and needs replacement before the ink lines are flushed through to the nozzles.
The ink tanks can be isolated from the printhead by a shut off valve upstream of the printhead. This protects the tanks from contamination during standby, but there is a risk that the tank and the printhead will generate a pressure difference during the standby period. If this happens, the sudden pressure equalization causes a pulse through the ink line which floods the nozzle plate.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides an inkjet printer comprising: a printhead for printing onto a media substrate; a reservoir for containing a quantity of ink, the reservoir having a lower portion for holding ink and an upper portion defining a headspace of air above the ink; a fluid connection extending between the printhead and the reservoir; and, a pump for drawing air from the headspace into atmosphere.
The invention uses a fluidic system that controls the air pressure in the headspace of an ink reservoir to control the hydrostatic pressure of the ink at the key points along the ink line. Controlling the ink pressure in one of the ink reservoirs (either the ink tank supplying the printhead or the ink sump collecting waste ink) can maintain a more consistent negative pressure (i.e. a hydroststatic pressure less than atmospheric) at the printhead nozzles. The negative pressure at the printhead nozzles prevents, or at least reduces color mixing by ensuring that the ink meniscus at each nozzle is drawn inwards. An inwardly drawn meniscus significantly reduces the chance that paper dust or residual ink can establish a fluid connection between nozzles of different color. Drawing air from the headspace in the sump helps to equalize the pressure in the different ink lines as the sump headspace is common to all the color channels. By the same token, it is a simple matter to use a single pump to connect the respective headspaces for each ink tank. In this way, the air pressure in each ink tank is equal and so the hydrostatic pressure of the ink at the nozzles will only vary by the variations in the ink levels of the ink tanks. In a normal usage profile, the ink levels remain roughly the same for each ink tank. To further minimize variations, the tanks can have a wide and squat shape to reduce the change in hydrostatic pressure from full to empty. With equal pressures (or at
least very nearly equal pressures) in each ink line, there is no pressure differential to drive a color mixing process other than diffusion. As the fluid connection across the nozzle is so small, mixing by diffusion is negligible.
Preferably, the reservoir is a sump that collects waste ink drained from the printhead.
Preferably, the reservoir is an ink tank for supplying ink to the printhead. In a further preferred form, the printer is a color printer for printing a plurality of differently colored inks, each of the differently colored inks being stored in a respective ink tank for supplying the printhead, the headspace of each of the tanks is connected to the pump such that they are in fluid communication with each other.
Preferably, the reservoir has a vent for venting the headspace to atmosphere, and for allowing a throttled flow of air into the headspace as the pump is drawing air out of the headspace. In a further preferred form, the vent has a filter for removing particulate contaminants from the throttled air flow into the headspace.
Preferably, the printing further comprises an upstream valve positioned upstream of the printhead. In a further preferred form, the printer further comprises a downstream valve positioned downstream of the printhead.
Preferably, the pump is reversible such that it can increase the air pressure in the headspace and force ink towards the printhead. In a further preferred form, the pump is used to prime the printhead. In anther preferred form, the pump is used to purge ink from the nozzles and flood the printhead.
Preferably, the printhead has a distribution manifold and a plurality of printhead integrated circuits mounted to the distribution manifold such that priming the distribution manifold with ink also primes the printhead integrated circuits. In some embodiments, the printer further comprises a maintenance station having a capper and blotter for the printhead integrated circuits. In specific embodiments, the pump is in fluid communication with the
maintenance station and the sump such that ink collected by the maintenance station can be transferred to the sump by running the pump in one direction and air drawn from the headspace by running the pump in the other direction. In a particularly preferred form, the printhead is provided as a user removable and replaceable cartridge which is fluidly detachable from the printer via the upstream and the downstream valves.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings in which:
Figure 1 shows a schematic diagram of a printer fiuidic system according to the present invention; and,
Figure 2 shows a schematic diagram of another printer fiuidic system according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figure 1, the printer fluidics system is shown schematically for the purposes of illustration. A single ink line for one color is shown in full. The ink tanks 10 and 12 for other color are shown in dotted line. A color printer would have complete ink lines for each ink color. Most of the individual components within the system are shown and described in much greater detail in the Applicant's co-pending application USSN 11/688863 (Our Docket RREOOlUS), filed on March 21, 2007, the contents of which are incorporated herein by cross reference. Components of the present system that are not shown in the cross referenced document, are commercially available.
The fluidic system shown in Figure 1 has a printhead 2 supplied with ink 14 from an ink tank 8 via an upstream ink line 20. Waste ink from the printhead 2 drains to a sump 28 through downstream ink line 24. The upstream ink line 20 has a shut off valve 18 and the downstream ink line has shut off valve 26. These valves can be used for priming and purging ink (discussed below) and as detachable fluid connections is the printhead is provided in the
form of user removable and replaceable cartridge such as that shown in the above referenced
USSN 11/688863 (Our Docket RREOOlUS), filed on March 21, 2007.
The printhead has a maintenance station 22 for capping and blotting the nozzles. A drain line 16 connects the maintenance station 22 to the sump 28.
The printhead 2 is an assembly of an ink distribution manifold 4 on which a series of printhead integrated circuits (ICs) 6 are mounted. The printhead ICs 6 define the nozzle arrays which eject the ink to the media substrate. The nozzles are MEMS devices which can be thermally actuated such as those described in USSN 11/482953 (Our Docket No. MTDOOlUS) filed on July 10, 2006 or mechanically actuated such as those disclosed in USSN 10/160273 (Our Docket No.MJ40US) filed June 4, 2002.
The ink distribution manifold 4 is an LCP molding with a system of large channels feeding a network of smaller channels to supply the ink to many points along the length of each printhead IC 6. An embodiment of the distribution manifold 4 and the printhead ICs 6 is disclosed in detail in the USSN 11/688863 (Our docket No. RREOOlUS) filed March 21, 2007 reference listed above. This document also details the manner in which the printhead is primed with ink or, if necessary, purged of ink to correct any cross channel color contamination and/or bubble removal.
In standby mode, the air pump 30 draws air from the headspace 32 in the tank 8. The air pressure in the headspace drops and air is drawn back into the headspace 32 through the filtered vent 40. The air constriction from the vent 40 is carefully controlled to create a predetermined negative air pressure. The tubing 38 fluidly connects the headspaces 34 and 36 in tanks 10 and 12 such that all the headspaces are at the same air pressure. Tanks 10 and 12 can have their own vents to atmosphere (not shown) but the system will operate with a single vent.
With the headspaces 32, 34, and 36 at the same pressure, the hydrostatic pressure in the ink is very early equal. The hydrostatic pressure of the ink at the nozzles will only vary by the
variations in the ink levels of the ink tanks. Normal usage is designed to keep the ink levels roughly the same in each ink tank. To further minimize variations, the tanks can have a wide and squat shape to reduce the change in hydrostatic pressure from full to empty. With equal pressures (or at least very nearly equal pressures) in each ink line, there is no pressure differential to drive a color mixing process other than diffusion. As the fluid connection across the nozzle is so small, mixing by diffusion is negligible.
The pump 30 is reversible so it can be used to pressurize the headspaces 32, 34 and 36 in order to prime the printhead 2 or purge ink through the printhead ICs 6. Priming requires the upstream and downstream shut off valves 18 and 26 to be open. Ink from the tanks 8, 10 and 12 is forced down the upstream ink line 20, through the distribution manifold 4 and into the sump 28 via the downstream ink line 24. The printhead ICs 6 prime by capillary action from the ink in the distribution manifold.
To purge the printhead ICs 6 (to recover dried nozzles, outgassing bubble blockages etc) the down stream valve 26 is closed as the pump 30 pressurizes the headspace 32. Ink is forced from the nozzles and the resulting flood on the nozzle plate is cleared with the maintenance station 22.
It will be appreciated that the pump 30 operates during a power up standby mode.
That is, during periods of inactivity between print jobs, but the printer is still plugged in and connected to a power supply. During a power off standby, the shut off valve 18 and 26 are closed to isolate the printhead and prevent mixing. When the printer powers up again, the pump 30 can be used to ready the printhead by priming or purging (if necessary) as discussed above.
Figure 2 shows the pump 30 operating on the headspace 32 of the sump 28 instead of the ink tank 8. Again, a single ink line is shown but the color printer will have several color lines all draining to the same sump 28. As long as all the down stream ink lines 24 for each color connect to the sump headspace, a single pump can be used to change the hydrostatic pressures in the ink at the nozzles.
With the pump 30 connected to the sump 28, the upstream shut off valve 18 is closed during power down standby. The negative air pressure in the headspace 32 draws on the column of ink hanging from the printhead 2. This ensures that a sufficiently negative pressure is maintained at the nozzles. More importantly, the negative pressure in the nozzles of each color is the same. As discussed above, this removes the mechanism that drives the color mixing process.
The pump 30 is marginally more complex in that it needs to be able to handle an ink/air mixture. It is in the drain line 16 from the maintenance assembly 22 to the sump 28 to assist the transfer of blotted ink to the sump 28 but needs to be able to draw air from the headspace 32 or from atmosphere through the filter 42.
In this embodiment, priming requires the upstream valve 18 to be open and the pump 30 to create a low pressure in the sump 28 to draw the ink from the tank 8 down the upstream ink line 20, through the distribution manifold 4 and into the downstream ink line 24. Again the printhead ICs 6 prime by capillarity.
To purge, the upstream valve 18 is closed and the pump 30 creates a positive pressure in the headspace 32 to force the ink in the down stream ink line 24 and the distribution manifold 4 to flood the printhead ICs 6.
The invention has been described by way of example only. Ordinary workers in this field will readily recognize any variations and modifications which do not depart from the spirit and scope of the broad inventive concept.
Claims
1. An inkjet printer comprising: a printhead for printing onto a media substrate; a reservoir for containing a quantity of ink, the reservoir having a lower portion for holding ink and an upper portion defining a headspace of air above the ink; a fluid connection extending between the printhead and the reservoir; and, a pump for drawing air from the headspace into atmosphere.
2. An inkjet printer according to claim 1 wherein the reservoir is a sump that collects waste ink drained from the printhead.
3. An inkjet printer according to claim 1 wherein the reservoir is an ink tank for supplying ink to the printhead.
4. An inkjet printer according to claim 3 wherein the printer is a color printer for printing a plurality of differently colored inks, each of the differently colored inks being stored in a respective ink tank for supplying the printhead, the headspace of each of the tanks is connected to the pump such that they are in fluid communication with each other.
5. An inkjet printer according to claim 1 wherein the reservoir has a vent for venting the headspace to atmosphere, and for allowing a throttled flow of air into the headspace as the pump is drawing air out of the headspace.
6. An inkjet printer according to claim 5 wherein the vent has a filter for removing particulate contaminants from the throttled air flow into the headspace.
7. An inkjet printer according to claim 1 further comprising an upstream valve positioned upstream of the printhead.
8. An inkjet printer according to claim 7 further comprising a downstream valve positioned downstream of the printhead.
9. An inkjet printer according to claim 1 wherein the pump is reversible such that it can increase the air pressure in the headspace and force ink towards the printhead.
10. An inkjet printer according to claim 9 wherein the pump is used to prime the printhead.
11. An inkjet printer according to claim 10 wherein the pump is used to purge ink from the nozzles and flood the printhead.
12. An inkjet printer according to claim 1 wherein the printhead has a distribution manifold and a plurality of printhead integrated circuits mounted to the distribution manifold such that priming the distribution manifold with ink also primes the printhead integrated circuits.
13. An inkjet printer according to claim 12 further comprising a maintenance station having a capper and blotter for the printhead integrated circuits.
14. An inkjet printer according to claim 13 wherein the pump is in fluid communication with the maintenance station and the sump such that ink collected by the maintenance station can be transferred to the sump by running the pump in one direction and air drawn from the headspace by running the pump in the other direction.
15. An inkjet printer according to claim 8 wherein the printhead is provided as a user removable and replaceable cartridge which is fluidly detachable from the printer via the upstream and the downstream valves.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/AU2007/001563 WO2009049348A1 (en) | 2007-10-16 | 2007-10-16 | Printer with reservoir headspace pressure control |
TW097106079A TWI415749B (en) | 2007-10-16 | 2008-02-21 | Printer with reservoir headspace pressure control |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/AU2007/001563 WO2009049348A1 (en) | 2007-10-16 | 2007-10-16 | Printer with reservoir headspace pressure control |
Publications (1)
Publication Number | Publication Date |
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WO2009049348A1 true WO2009049348A1 (en) | 2009-04-23 |
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Application Number | Title | Priority Date | Filing Date |
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PCT/AU2007/001563 WO2009049348A1 (en) | 2007-10-16 | 2007-10-16 | Printer with reservoir headspace pressure control |
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TW (1) | TWI415749B (en) |
WO (1) | WO2009049348A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3172054A4 (en) * | 2014-07-25 | 2018-04-04 | Hewlett-Packard Development Company, L.P. | Regulator component |
WO2020096605A1 (en) * | 2018-11-08 | 2020-05-14 | Hewlett-Packard Development Company, L.P. | Refill containers with pressurized fluid chambers |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
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JP6537243B2 (en) * | 2013-11-22 | 2019-07-03 | キヤノン株式会社 | Liquid discharge apparatus, method of controlling liquid discharge apparatus, imprint apparatus and method of manufacturing parts |
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EP0082272A1 (en) * | 1981-12-17 | 1983-06-29 | International Business Machines Corporation | Ink jet printers and methods of operating such printers |
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EP0082272A1 (en) * | 1981-12-17 | 1983-06-29 | International Business Machines Corporation | Ink jet printers and methods of operating such printers |
US4494124A (en) * | 1983-09-01 | 1985-01-15 | Eastman Kodak Company | Ink jet printer |
US6991313B2 (en) * | 2002-07-26 | 2006-01-31 | Brother Kogyo Kabushiki Kaisha | Ink jet printer and main maintenance method |
JP2005125669A (en) * | 2003-10-24 | 2005-05-19 | Sony Corp | Head cartridge and liquid ejector |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3172054A4 (en) * | 2014-07-25 | 2018-04-04 | Hewlett-Packard Development Company, L.P. | Regulator component |
WO2020096605A1 (en) * | 2018-11-08 | 2020-05-14 | Hewlett-Packard Development Company, L.P. | Refill containers with pressurized fluid chambers |
US11577520B2 (en) | 2018-11-08 | 2023-02-14 | Hewlett-Packard Development Company, L.P. | Refill containers with pressurized fluid chambers |
Also Published As
Publication number | Publication date |
---|---|
TWI415749B (en) | 2013-11-21 |
TW200936386A (en) | 2009-09-01 |
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