TWI430893B - Ink pressure regulator with improved liquid retention in regulator channel - Google Patents

Description

Ink pressure regulator with improved liquid retention in the regulator passage

The present invention relates to a pressure regulator for an ink jet printer that is primarily developed for generating negative hydrostatic pressure in an ink supply system to supply ink to a printhead nozzle.

The inkjet printheads described in the above-referenced cross-reference documents generally include array nozzles, each nozzle having a combined inkjet actuator for ejecting ink from a nozzle opening defined in the top of the nozzle chamber. Ink from ink cartridges or other reservoirs is fed to the chamber where the ejection actuator forces ink droplets through the ink opening for printing. Ink cartridges are typically replaceable and consumable in inkjet printers.

The ink can be drawn into each nozzle chamber by the suction force after each drop and by the capillary action of the ink supply passage having a hydrophilic surface such as a ceria surface. During the inactive period, the surface tension of the meniscus at the entire edge of each nozzle opening is pinned, and the ink is retained in the nozzle chamber. If the ink pressure is not controlled, the ink pressure may become a positive pressure relative to the external atmospheric pressure due to thermal expansion of the ink, or because the ink is raised above the level of the nozzle due to tilting or tipping over the printer. The ink in this case will spill over the surface of the print head. Further, during the printing action, the ink supplied through the ink supply path has a momentum sufficient to cause the ink to flow out of the nozzle and flood the printing head surface when the printing is stopped. In any situation, you don't want to print the head.

To solve this problem, many printhead ink supply systems are designed such that the hydrostatic pressure of the ink is less than atmospheric pressure. This causes the entire meniscus of the nozzle opening to be concave or pulled inward. During the inactive period, the meniscus is fixed at the nozzle opening, and the ink does not flow freely out of the nozzle. Furthermore, the surface flooding caused by the ink rushing is minimized.

The amount of negative pressure in the chamber is limited by two factors. The negative pressure should not be large enough to de-prime the chamber (ie, draw the ink from the chamber and return to the crucible). However, if the negative pressure is too small, the nozzle will leak ink to the print head face, especially if the print head is shaken. In addition to these two catastrophic events that require some form of correction (such as printhead maintenance or refilling), the second best hydrostatic ink pressure typically causes an array image defect during printing, which has a visible print quality. Lost. Thus, an ink jet printer can have a relatively narrow window of hydrostatic ink pressure that must be achieved by a pressure regulator in the ink supply system.

The ink cartridge is typically designed to incorporate some means to adjust the hydrostatic pressure of the ink supplied from the ink cartridge. In order to create a negative pressure, some 匣 use a flexible bag design. A portion of the crucible has a flexible pocket or wall section that is biased toward increasing the ink storage volume. USSN 11/014764 (our file: RRB 001US) and USSN 11/014769 (our file: RRC 001US) (listed in the cross-reference file above) are examples of this type. These turns can provide negative pressure, but tend to rely on the excellent manufacturing tolerances of the inner leaf springs in the flexible bag. Moreover, the requirements of internal biasing devices in flexible bags create important manufacturing challenges.

Figure 24 shows another device for generating negative ink pressure by ink cartridges. A piece of foamed or porous material 2 is placed over the outlet 3 in the crucible 1 which has a section 4 for holding the ink and a section 5 which is wetted by the ink but does not absorb the ink. The top of the crucible 1 is vented to the atmosphere via the air meandering 7. Capillary action (represented by arrow 6) draws ink from the saturating section 4 into the non-sucking section 5, which continues until the weight balance of the increased hydrostatic pressure, or the ink drawn up by the capillary action 6 The weight of the head is balanced. Since capillary action enters the unsaturated section 5, the hydrostatic pressure at the top of the saturated section 4 is less than atmospheric pressure. The hydrostatic pressure is increased from here to the pressure at the outlet 3, and if connected to a print head (not shown), the hydrostatic pressure continues to increase down to the nozzle opening (assuming the nozzle opening is the lowest point in the print head) . By setting the ratio of the full-foaming to the non-saturated foaming, the ink hydrostatic pressure at the nozzle is less than atmospheric pressure, so the ink meniscus will have an inward shape.

However, ink cartridges containing foamed inserts are generally not suitable for high speed printing using the applicant's page wide print head (e.g., print rate per page of 1-2 seconds), which is less than 1600 dpi wide. Rate printing. In this high speed printer, there are a large number of nozzles that have a higher firing rate than conventional scanning printers. Therefore, the ink flow rate from the crucible is much larger than the scanning print head. The fluid resistance caused by the foamed insert can cause the ink to come out of the nozzle and slow down the cavity to be a refill rate. The porous foam with more pores has less fluid resistance, but also greatly reduces the capillary force. Furthermore, precise pressure control requires an equal amount of precise control of the internal void size, which is difficult to achieve by randomly forming a void structure of most foamed materials. Therefore, porous foaming is not considered as controlling high inks. A viable device for flow rate ink pressure.

As another embodiment (or in addition) of an ink cartridge having an integrated pressure regulator, the ink supply system can include a pressure regulator within the ink line between the printhead and the ink reservoir. The applicant of the case has previously applied for US No. 11/293806 (Attorney Docket No. RRD 011US, Application on December 5, 2005) and US 11/293842 (Attorney Case No. RRD 008US, Application on December 5, 2005) No. Patent, the contents of which are incorporated herein by reference. The second case describes a pressure regulator along the line that includes a diaphragm and a biasing structure that is used to generate a negative hydrostatic ink pressure at the printhead. However, this type of mechanical pressure regulator has the disadvantage of requiring extremely precise manufacturing tolerances on the spring that react to open or close the diaphragm depending on variations in ink pressure upstream and downstream of the membrane surface. In practice, this pressure controlled mechanism system makes it difficult for the ink supply system to maintain a constant negative hydrostatic ink pressure within a relatively narrow pressure range.

It is therefore desirable to provide a pressure regulator that is adapted to maintain hydrostatic pressure within a relatively narrow pressure range. It is further desirable to provide a pressure regulator that is suitable for use at relatively high ink flow rates. It is also desirable to provide a pressure regulator that is simple in construction and that does not require excessively high precision tolerances to manufacture moving parts. Furthermore, it is desirable to provide a pressure regulator that does not leak ink due to pressure variations during temperature cycling.

In a first aspect, an ink pressure regulator is provided for regulating a hydrostatic pressure of ink supplied to an inkjet print head, the regulator package Including: an ink chamber having an ink outlet for fluid communication with the printhead via an ink line; an air inlet; a regulator passage having a first end connected to the air inlet and a head communicating with the chamber a second end of the space defining a bubble outlet; a wet system for maintaining at least some of the liquid within the regulator passage, thereby ensuring that air entering the head space first passes the liquid; the wet system comprising: a first wet chamber coupled to the first end; a second wet chamber coupled to the second end; and a liquid retaining formation disposed in at least one of the wet chambers such that the regulator passage, The first wet chamber, the second wet chamber, and the liquid retaining configuration are all in fluid communication with each other; wherein the regulator passage is sized to control the outlet from the bubble by supplying ink to the print head The Laplacian pressure of the bubble is taken, thereby adjusting the hydrostatic pressure of the ink.

The present invention advantageously provides an excellent adjustment of the hydrostatic ink pressure using bubble point pressure adjustment. The hydrostatic ink pressure can be controlled to be less than atmospheric pressure of at least 10 mm H ₂ O, less than atmospheric pressure of at least 25 mm H ₂ O, less than atmospheric pressure of at least 50 mm H ₂ O, or less than atmospheric pressure of at least 100 mm H ₂ O. Pressure regulation is achieved by designing the size of the regulator passage (and associated bubble outlet). For example, the regulator channel can have a critical depth dimension of less than 200 microns, less than 150 microns, less than 100 microns, or less than 75 microns to achieve the desired hydrostatic ink pressure during printing.

A particular advantage of the present invention is that the regulator passage remains wet throughout the life of the pressure regulator. This advantage is achieved by a wet system comprising a first wet chamber, a second wet chamber, and a liquid holding configuration.

The liquid is typically the same type of ink supplied to the printhead.

Optionally, during use, the liquid held by the wet system is isolated from the reservoir ink contained within the ink chamber.

The liquid retaining configuration is typically disposed within the second wet chamber.

Optionally, the liquid retaining configuration is constructed such that liquid from the bursting bubble is drawn by the liquid retaining configuration. Thus, the liquid from the bursting bubble is retained within the wet system and does not escape into the ink body via the head space.

Optionally, the second wet chamber is elongate and the liquid retaining formation extends along the length of the second wet chamber. This configuration advantageously causes the bubbles to burst within the second wet chamber and maintains the liquid within the bubbles by the body retaining configuration.

Optionally, the liquid retaining structure is in spatial communication with the head. Optionally, the liquid retaining structure is in direct communication into the head space. This configuration advantageously facilitates confining saturated ink vapor within the head space by the liquid retention configuration. Again, the ink preparation is transferred to the liquid holding configuration during transport or when the pressure regulator (which may be an ink cartridge) is tilted or tipped over. This provides a useful mechanism by which the wet system can be replenished with ink.

Optionally, the liquid retaining structure retains the liquid by capillary action body. Any configuration with a suitable curvature can be used to retain the liquid by capillary action.

Optionally, the liquid retaining formation is defined by one or more liquid retaining holes defined in the wall of the second wet chamber, the liquid retaining holes communicating into the head space.

Optionally, the liquid retaining formation is defined by a plurality of grooves defined within the wall of the second wet chamber. The slots may extend substantially along the entire length of the second wet chamber and communicate into the head space.

Optionally, the liquid retaining construction is a sponge. Likewise, the sponge can be elongate and extend generally along the entire length of the second wet chamber. The sponge communicates into the head space and absorbs ink during transport or when the pressure regulator is tilted or tipped over.

Optionally, the liquid retaining formation includes one or more liquid retaining surface features defined within the wall of the second wet chamber.

Optionally, the liquid retaining formation includes a plurality of grooves defined within the wall of the second wet chamber.

Optionally, the first wet chamber is connected to the atmosphere via the air inlet.

Optionally, the second wet chamber has a bore that communicates into the head space.

Optionally, the wet chambers, the regulator passages, and the liquid retaining configuration together maintain a substantially constant amount of liquid.

Optionally, each wet chamber is constructed such that liquid is secured into the edge regions of the wet chambers, the edge regions being connected to the regulator passage Road.

Optionally, each wet chamber is substantially beveled such that the edge regions comprise at least two chamber walls that meet at an acute angle.

Optionally, during idle periods, the positively pressurized head space forces liquid to be transferred from the second wet chamber to the first wet chamber.

Optionally, positively pressurized air within the head space is first passed through the liquid and escapes via the air inlet.

Optionally, the air inlet, the regulator passage, and the wet system are disposed on top of the ink chamber. This configuration maximizes the amount of liquid that the wet system can maintain and also facilitates the installation of a pressure regulator (which is typically a replaceable ink cartridge) within the printer.

Optionally, the pressure regulator defines an ink cartridge for an inkjet printer.

Pressure regulator with circular bubble outlet

Figure 1 shows the simplest form of the invention to explain the operating principle of the pressure regulator. The pressure regulator 100 shown in FIG. 1 includes an ink chamber 101 having an ink outlet 102, and an ink inlet 103. In addition to this, the ink chamber 101 is sealed. The ink outlet 102 is used to supply the ink 104 to the print head 105 via the ink line 106. The bubble outlet 107 is connected to the air inlet 103 via an air passage 108.

When the print head 105 draws ink 104 from the ink chamber 101, the displaced ink volume must be equilibrated with an equal amount of air that passes through the air. The inlet 103 is broken into the chamber. A bubble outlet 107 located below the ink level ensures that air enters the chamber 101 in the form of bubbles. The size of the bubble outlet 107 determines the size of the bubble 109 entering the chamber 101.

As shown in Figure 2, the air passage 108 takes the form of a simple cylindrical passage so that the bubble outlet 107 is defined by a circular opening at one end of the cylindrical passage. Therefore, any air passing through the passage must be limited at some point by the surface of the liquid having a radius of curvature no greater than the inner diameter of the passage.

During printing, the nozzle of print head 105 effectively acts as a pump that draws ink from ink chamber 101 with each drop of spray. If the ink chamber is freely open to the atmosphere with an air opening (such as an opening in some conventional ink cartridges), the hydrostatic ink pressure of the ink supplied to the print head will simply be in the ink reservoir. The height above or below the print head is determined. However, in the ink chamber 101, each time a small amount of ink is drawn from the chamber 101, the pressure formed inside the bubble 109 of the bubble outlet 107 must be overcome. Once the pumping effect of the nozzle produces a pressure sufficient to match the pressure formed inside the bubble 109 of the bubble outlet 107, the bubble can exit into the reservoir of ink 104 and the ink can flow from chamber 101 through ink outlet 102. .

Therefore, the bubble 109 formed at the bubble outlet 107 provides a back pressure against the pumping effect of the print head nozzle. In other words, the effect of the bubble outlet 107 is to create a negative hydrostatic ink pressure in the ink supply system.

The pressure inside the spherical bubble 109 is determined by the well-known Laplace equation: ΔP = 2 γ / r Where: ΔP is the pressure difference between the inside of the bubble and the ink; r is the inner diameter of the bubble; and γ is the surface tension of the interface between the ink and the air.

The size of the bubble 109 can be changed by changing the size of the bubble outlet 107. Thus, the size of the bubble outlet 107 provides means for establishing a predetermined negative hydrostatic pressure of the ink supplied to the printhead 105. The smaller bubble exit size provides greater negative hydrostatic ink pressure by creating smaller bubbles with higher Laplacian pressure.

In the pressure regulator 100 described above, the air passage is a small bore cylinder (e.g., a hypodermic needle) having a circular opening defining a bubble outlet 107. However, an important problem with this design is that the circular bubble outlet 107 has a very small area (having a rating of about 0.02 square millimeters) and is easily blocked by dirt in the ink. It is therefore desirable to increase the area of the bubble outlet 107 to make it more robust and durable even if there is dirt in the ink.

Pressure regulator with grooved bubble outlet

As shown in Figure 3A, the bubble outlet 107 of the improved design uses a slot 110 that is open relative to the circle. The slot has a length dimension L and a width dimension W. The bubbles 109 in which the grooves are present typically have a cylindrical front that extends the length of the groove. As explained below, the curvature of the bubble 109 of the groove and the Laplace pressure of the bubble are mainly determined by the width dimension.

In the case of non-spherical bubbles, the Laplace pressure is given by: ΔP = γ / r ₁ + γ / r ₂ where: ΔP is the pressure difference between the inside of the bubble and the ink; r ₁ is the width of the bubble Size; r ₂ is the length dimension of the bubble; and γ is the surface tension of the interface between the ink and the air.

In practice, the length of the groove is much larger than the width (r ₂ >> r ₁ ), and the Laplace pressure of the bubble having the groove at the end of the cylinder becomes: ΔP = γ / r ₁ or 2 γ / W ( Because W=2r ₁ )

It will thus be appreciated that the width of the slot 110 is the only critical dimension that controls the Laplace pressure of the bubble 109 in which the slot is present.

FIG. 3B shows a hypothetical situation in which a piece of debris 111 catches the slot 110. But unlike the case of a circular opening, the slot 110 still controls the critical curvature of the bubble in which the slot is present. There may still be grooves 110 with cylindrical end bubbles 109, as shown in Figure 3B. The slot 110 thus maintains excellent control of the hydrostatic ink pressure while providing a more robust design of the bubble outlet 107.

In the embodiment discussed so far, the size of the air passage 108 mirrors the size of the bubble outlet 107. This is not an essential feature of the regulator and can in fact adversely affect the efficacy of the regulator, especially at high flow rates. The inherent viscosity of the air can cause large flow impedance or hydraulic resistance in the air flow path. According to the (Pouiseille's) equation, the flow rate and the tube radius r have a relationship of r ⁴ . Therefore, the problem of flow impedance is more serious in channels with very small radii.

In the present invention, the critical size of the bubble outlet 107 is selectively small It is about 200 microns, or alternatively less than about 150 microns, alternatively less than about 100 microns, alternatively less than about 75 microns, and optionally less than about 50 microns. The critical dimension of the bubble outlet can be selectively in the range of 10 to 50 microns, or 15 to 40 microns. "Key size" means the size of the bubble outlet that determines the curvature, and the Laplace pressure of the bubble.

These dimensions need to provide the desired negative hydrostatic ink pressure. For a print-size printhead, the pressure is selectively at least 10 mm H ₂ O, or alternatively at least 30 mm H ₂ O, or alternatively at least 50 mm H ₂ O. For an A4-size printhead, the desired negative hydrostatic ink pressure is selectively at least 100 mm H ₂ O, or alternatively at least 200 mm H ₂ O, or alternatively at least 300 mm H ₂ O . Negative hydrostatic pressure selectively within 100 to 500mm H ₂ O, or the range of 150 to 450mm H ₂ O is.

An air passage 108 having a width of less than 200 microns creates an important flow resistance to the air entering the passage. If air cannot pass through the channel 108 at the same flow rate as the ink is supplied to the printhead 105, the print head will produce a catastrophic de-prime at high print rates.

Therefore, it is desirable to construct the air passage 108 such that each cross section of the air passage is larger than the critical dimension of the bubble outlet 107. Thus, with respect to the trough-like bubble outlet 107 shown in FIG. 3A, the air passages 108 should selectively have each cross-sectional dimension greater than the width W of the trough 110.

However, it is important that the volume of the air passage 108 is not too large. When the print head 105 is idle, the ink rises in the air passage 108 by capillary action. This ink is before the bubble 109 is drawn into the ink chamber 101 The volume must be pulled through the air passage 108 by the printhead and reach the optimum hydrostatic ink pressure for printing. Therefore, the volume of ink drawn into the air passage 108 by capillary action during idle time is wasted because it cannot be printed with the optimum print quality.

The capillary volume of the ink increases with the radius of the air passage. Thus, the cross-sectional dimension (e.g., radius) of the ink channel 108 should not be selectively too large such that the maximum capillary volume exceeds about 0.1 milliliters of ink, which is an effective ink dead volume. Optionally, the largest ink capillary volume in the air passage is less than about 0.08 milliliters, or alternatively less than 0.05 milliliters, or alternatively less than 0.03 milliliters.

Figure 4 shows another embodiment of an ink pressure regulator having the bubble outlet 207 and air passage 208 contemplated above. The pressure regulator 200 includes an ink chamber 201 having an ink outlet 202. A side wall of the ink chamber 201 is defined by a layered air introduction plate 210 that includes a first planar layer 211 and a second planar layer 212. The first planar layer 211 and the second planar layer 212 have a first face 211 and a second face 212, respectively. The first face 211 and the second face 212 collectively define an air inlet 203, an air passage 208, and a bubble outlet 207. The air inlet 203 can optionally include an air filter (not shown) for filtering particles that are drawn into the ink chamber 201.

The ink chamber 201 also includes a one-way pressure relief valve 219; the one-way pressure relief valve 219 is normally closed during operation of the pressure regulator 200. Valve 219 is constructed to relieve any positive pressure within head space 240 above ink 104, which may result, for example, from thermal expansion of the amount of air confined within the head space during typical day/night temperature changes. Because of the positive pressure The forced ink in the air passage 208 rises out of the air outlet, causing considerable loss of ink from the chamber 201, so a positive pressure within the head space 240 is undesirable.

Referring to FIG. 6, the first layer 211 of the air introduction plate 210 has an air inlet opening 213 defined therethrough and an elongated recess 214 defined in the first face 221 in the form of a groove. The elongated recess 214 extends from the air inlet opening 213 to the end region of the recess, the end region of the recess comprising a circular recess 216. The circular recess 216 has a relatively shallow depth relative to the generally concave portion 214. Still referring to FIG. 6, the second layer 212 has a bubble aperture opening 217 defined therethrough. As understood from Figures 4 and 6, when the first face 221 and the second face 222 are stacked together, the recess and the opening collectively define an air inlet 203, an air passage 208, and a bubble outlet 207.

FIG. 5 shows the bubble exit region 220 of the air introduction plate 210 in detail. A circular recess 216 that is shallower than the elongated recess 214 defines a constriction 218 within the air passage 216. The constricted portion 218 defined by the depth of the circular recess 216 in the first face 221 defines the critical width dimension for the bubble exit 207. The bubble exit 207 thus takes the form of an annular slot and the length of the slot is defined by the circumference of the bubble aperture opening 217 of the second layer 212.

The advantage of having an annular groove is that it maximizes the length of the groove, thereby improving the ability of the bubble outlet 207 to cope with particulate contamination. An advantage of having a relatively deep elongate recess 214 is that it minimizes the flow impedance within the air passage 108, which is collectively defined by the recess 214 and the second face 222. The elongated recess 214 typically has a range of 0.2 to 1 mm or 0.2 to 0.5 mm. The depth in the circumference and the width in the range of 0.5 to 2 mm or 0.7 to 1.3 mm.

Still referring to FIG. 5, it can be seen that the inner face 231 of the bubble opening 217 is inclined to optimize the escape of the bubble from the bubble outlet 207.

Referring to FIG. 7, the first layer 211 of the air introduction plate 210 may have a sulcus 230 defined within the first layer 211. The gutter 230 surrounds the structural features defined within the first layer 211 and importantly protects the elongate recess 214 and the circular recess 216 from the adhesive of the lamination process. Any excess wicking wicking or wicking between the first side 221 and the second side 222 is captured by the sulcus 230 because the capillary action can only transport liquid into the once reduced size configuration and through the sulcus Any path includes an area of increased size. This prevents clogging of the air inlet passage 208 or the bubble opening 207, which is defined by the stacking of two layers. Therefore, the sulcus 230 is a structural feature that facilitates the manufacture of the air introduction plate 210.

Of course, it should be understood that the air introduction plate can take many different forms and can be defined, for example, by more than two laminar layers. Figure 8 shows an air introduction opening 250 defined by three layers. The first layer 251 has a defined air inlet opening 252; the second layer 253 extends through the defined bubble aperture opening 254; and the third film layer 255 is sandwiched between the first layer and the second layer. The film layer 255 has a defined air passage opening 256 so that when the three layers are stacked together, a fluid path is defined from the air inlet to the bubble outlet. The thickness of the film layer 255 defines the depth of the air passage and the critical dimension of the bubble outlet at the end of the air passage.

Tables 1 through 4 below show the hydrostatic ink pressures of the pressure regulators 200 shown in Figures 4-6. Four pressure regulators are constructed to form critical dimensions with different bubble outlets 207. Dynamic pressure measurements were taken at various flow rates and static pressure measurements were taken by stopping the flow of ink. Dynamic pressure loss is the difference between the dynamic adjustment pressure and the static regulation pressure.

Excellent ink pressure control can be achieved simply by changing the size of the bubble outlet.

Furthermore, the pressure measurement confirmed that the bubble was generated according to the Laplace equation. And found that the average static regulation pressure follows the following equation: P = -0.0067 / W + 18.3 where: P is the average static adjustment pressure expressed in millimeters of water column (mm H ₂ O); W is the width of the bubble outlet expressed in microns; and 18.3 It is the offset pressure due to the ink level in the chamber.

Substituting the first term of the Laplace equation, the surface tension γ of the ink was calculated to be 33.5 mN/m. The independent surface tension measurement of the ink is closely related to this calculated number.

Ink cartridge containing pressure regulator

As shown in Figure 4, the pressure regulator 200 includes an ink chamber 201 that defines an ink reservoir for the printhead. Because of the simplicity and low cost manufacturing of the pressure regulator 200, it can be constructed as a replaceable ink cartridge for use with jet printers. Therefore, the pressure regulator is also replaced each time the ink cartridge is replaced. An advantage of this design is that long term soiling or blockage of the pressure regulator 200 is avoided because the pressure regulator 200 is periodically replaced during the life of the printer.

Replaceable ink cartridge connected to a pressure regulator

In an alternative embodiment, the pressure regulator can be a permanent component of the printer. In this alternative embodiment, a pressure regulator is constructed for attaching the replaceable ink cartridge. Thus, in the embodiment illustrated in Figure 9, the pressure regulator 200 is coupled to the replaceable ink cartridge 280 by a pair of connectors. The ink connector 281 connects the ink supply port 282 of the ink cartridge 280 to the ink inlet port 283 of the ink chamber 201. The ink supply portion 282 and the corresponding ink inlet portion 283 are disposed near the bottom of the ink cartridge 280 and the ink chamber 201, respectively, to maximize the use of the ink 104 stored in the crucible.

The equal pressure connector 285 is disposed to equalize the pressure in the head space 240 of the ink chamber 201 and the head space 241 of the ink cartridge 280. Corresponding equal pressure portions 286 and 287 are disposed near the tops of the ink chamber 201 and the ink cartridge 280, respectively.

When the ink cartridge 280 is empty, the ink cartridge 280 is removed from the ink connector 281 and the isopipe connector 258 and moved away from the printer. The ink cartridge can then be installed in the printer by the reverse process. Although only shown schematically in FIG. 9, it will be readily appreciated that the ink cartridges 280 can have suitable ports 282, 287 that are configured to seal the intermeshing ink connections when the ink cartridges are mounted in the printer. 281 and isobaric connector 285. Ports suitable for this sealing engagement are well known in the art.

As shown in FIG. 9, an ink inlet port 283 and an isostatic pressure 286 are defined in the side walls of the ink chamber 201, which are opposite to the air introduction plate 210. However, the turns 283 and 286 may of course also be defined within the air introduction plate 210 to simplify the structure of the pressure regulator 200.

Bubble outlet in the head space with ink capillary supply

In the pressure regulator described in FIG. 4, a bubble outlet 207 is provided to allow the bubble 209 to enter the body of the ink 104 contained in the ink chamber 201. The bubble outlet 207 is typically disposed near the bottom of the chamber 201 to maximize ink usage at optimal hydrostatic pressure and the air inlet 203 is disposed near the top of the chamber. A problem with this configuration is that the air in the head space 240 is heated during idle to increase the pressure in the head space and force the ink up and down the air passage 208. The 203 exits, so the ink 104 contained within the chamber 201 can easily escape upwardly along the air passage 208 and escape from the air inlet 203. This temperature change is unavoidable and can result in a large amount of ink wasted.

As described above, one means of solving this problem is to incorporate the pressure relief valve 219 into the ink chamber 201. This valve 219 is constructed to release any positive pressure within the head space 240. However, this type of valve greatly increases the cost and complexity of the pressure gauge. Therefore, the pressure relief valve 219 makes the pressure regulator 200 less likely to be incorporated into the disposable ink cartridge.

It is therefore desirable to provide an ink pressure regulator that does not waste ink during temperature fluctuations and that does not require a pressure relief valve, so that the ink pressure regulator is easier to incorporate into the disposable ink cartridge.

Figure 10 shows an ink pressure regulator 300 that satisfies the above criteria. The ink pressure regulator is similar in design to that shown in Figure 4 and still relies on controlling the Laplace pressure of the bubbles entering the ink chamber. However, unlike the bubbles entering the body of the ink contained in the chamber, the bubble in this figure is the head space above the ink body entering the chamber. As will be explained in more detail below, this design allows any excess pressure in the head space during idle to be expelled from the air inlet.

Referring to FIG. 10, the ink pressure regulator 300 includes an ink chamber 301 having an ink outlet 302. A side wall of the ink chamber 301 is defined by a laminated air introduction plate 310; the air introduction plate 310 includes a first planar layer 311 and a second planar layer 312; the first planar layer 311 and the second planar layer 312 collectively define air Inlet 303, bubble outlet 307, bubble aperture 305, air (or regulator) channel 308, capillary channel 315, and capillary inlet 316. The bubble outlet 307 and the bubble aperture 305 are disposed above the ink level in the chamber 301, so the bubble 309 enters the head space 340 of the chamber via the bubble aperture. The bubble outlet 307 is connected to the air inlet 303 via an air passage 308. The bubble outlet 307 is generally trough shaped and is dimensioned to control the Laplace pressure of the bubble 309 as it is drawn from the ink inlet 302.

However, in contrast to the previous embodiment, the bubble 309 is formed by air passing through the ink meniscus fixed to the entire bubble outlet 307 and adjacent to the bubble opening 305, as more clearly shown in FIG. The bubble 309 thus formed emerging from the bubble outlet 307 escapes from the bubble hole 305 and enters the head space 340 of the ink chamber 301. Because the air must pass through the ink meniscus, the bubble 309 is defined by an air pocket that is confined to the inside of a thin layer of ink, rather than being defined by the entire ink body. Nevertheless, the same Laplace pressure control as described above can still be obtained.

The capillary inlet 316 provides fluid communication between the body of the ink 104 within the chamber 301 and the capillary channel 315, which is defined between the two layers 311 and 312. The capillary channel 315 is constructed to provide sufficient capillary pressure such that the ink column 304 rises along the channel to at least as high as the bubble exit 307, thereby ensuring that the bubble 309 is formed by the air passing through the ink meniscus. The capillary pressure is sufficiently high to form a meniscus throughout the bubble outlet 307 and the bubble aperture 305 after each bubble 309 is vented into the head space 340.

As shown in Figures 11 and 12, the size of the bubble aperture 305 is designed such that the ink column 304 has a meniscus that is fixed throughout the surface tension. hole. However, the bubble holes 305 cannot be too small, otherwise they are easily blocked by the particles. It has been found that the bubble holes 305 having a diameter of about 1 mm are suitable.

In practice, during idle periods, when there is no significant pressure in the head chamber 340 in the ink chamber 301, the ink column 304 rises above the ink outlet 307 and is typically secured to the entire inlet of the air passage 308, as shown in FIG. .

An important advantage of this embodiment is demonstrated in Figure 13. Figure 13 shows the situation in which positive pressure is established within the headspace 340 during idle periods. The pressurized air forces any ink to exit the air passage 308 and the air escapes from the chamber 301 via the air inlet 303. Therefore, when the head space 340 is pressurized due to an increase in temperature, only a small amount of ink escapes from the chamber 301.

Another advantage of this embodiment is that the air passage 308 is relatively short, thereby minimizing any flow impedance within the air passage and allowing for high flow rates of ink from the chamber 301 with optimal pressure control. Any flow resistance problems are thus avoided (such as those described with respect to the embodiment of Figure 4).

a bubble outlet that vents into the head space and is isolated from the body of the ink

In the above embodiment with respect to FIGS. 10 to 14, the bubble outlet 307 and the bubble opening 305 are disposed in the head space 340 of the pressure-to-heart gas 300. As shown in FIG. 13, this configuration helps to minimize ink leakage through the air inlet 303 due to pressure changes in the head space.

But even if the pressure regulator 300 is constructed in this manner, there is still a structure that allows the ink in the chamber 301 to be detached by the structure. Since the capillary channel 315 provides fluid communication between the air inlet 303 and the body of the ink 104, The ink may then be pumped up the capillary channel by the positive head space pressure. If the ink is pumped up along the capillary channel 315, the venting structure shown in Figure 13 will be rendered ineffective and still cause a significant amount of ink loss. It is therefore desirable to provide an ink pressure regulator whereby ink losses due to temperature/pressure changes in the head space are further minimized.

15 through 19 show an ink pressure regulator 400 that solves the problem of ink loss through the air inlet. The pressure regulator includes an ink chamber 401 that contains a reservoir of ink 104 and an ink outlet 402 for supplying ink to the printhead. Pressure adjustment similar to the above embodiment was obtained. Therefore, the bubble having the predetermined Laplace pressure is separated from the bubble outlet by the meniscus passing through the ink, and the exhaust gas enters the head space 440. However, unlike the embodiment shown in FIG. 10, during normal use, the bubble outlet and air inlet are isolated from the body of ink 104 contained within chamber 401. This ensures that ink loss is minimal when the pressure regulator 400 is used in a printer. Prior to installation in the printer (eg, during shipping), all inlet and outlet ports within the chamber 401 can be plugged to prevent ink leakage.

Referring to Figure 15, the sidewalls of the ink chamber 401 are defined by a laminated air introduction plate 410 that includes first and second planar layers 411, 412. These planar layers collectively define first and second wet chambers 450, 460. The first and second wet chambers 450, 460 are interconnected by a regulator passage. One end of the regulator passage 415 defines a bubble outlet 407, and thus a critical dimension is designed to control the Laplace pressure of the bubble exiting the bubble outlet.

The first wet chamber 450 communicates with the atmosphere via the air inlet 403, and the second wet chamber 460 communicates with the head space of the ink chamber 401 via the aperture 405. 440.

The first and second wet chambers 450, 460 together maintain a constant volume of liquid (typically ink) and are used to ensure that the regulator passage 415 is always wet. (In the above embodiment, this function is performed by the capillary channel 315.) Of course, it is important that the regulator passage 415 and the bubble outlet 407 are never dried when the regulator is required to perform the printing operation, otherwise the air can simply It flows into the head space 440 and the pressure regulator fails.

Ink can be transported between the first and second wet chambers 450, 460 via a regulator passage 415. Thus, the amount of ink held in each of the first and second wet chambers 450, 460 can be based on whether the bubble adjuster 400 supplies ink to the connected printhead during printing, or whether the bubble regulator is Idle and change.

Referring now to Figure 16, an enlarged view of the regulator passage 415, the first wet chamber 450, and the second wet chamber 460 during idle periods is shown. Each wet chamber has inclined walls 451, 461. In the first wet chamber 450, the wall 451 is inclined toward the air inlet 403; in the second wet chamber 460, the wall 461 is inclined toward the hole 405. This tilt (or chamfering) ensures that the ink is held in each chamber. The ink is fixed into the edge region of each chamber by surface tension and forms an ink ring around each chamber. The ink first ring 452 retained within the first wet chamber 450 is in fluid communication with the ink second ring 462 retained within the second wet chamber 460 by the regulator passage 415. Thus as the amount of first ring 452 decreases, the amount of second ring 462 will increase correspondingly; vice versa. As will be explained in more detail below, the ink transfer between the first and second wet chambers 450, 460, Allows the pressure regulator to achieve pressure regulation while minimizing ink leakage.

Referring to Figure 17, an enlarged view of the regulator passage 415 and the wet chamber during printing is shown. The pumping action of the print head (not shown) connected to the ink outlet 402 draws air into the air inlet 403. Air pushes the ink from the first wet chamber 450 down to the regulator passage 415 and into the second wet chamber 460. Thus the volume of the second ring 462 relative to the first ring 452 is increased. At the bubble exit 407 where the regulator channel 415 and the second wet chamber 350 meet, a bubble 409 is formed and the bubble 409 enters the second ring 462 of ink. This bubble escapes the second ring 462 and enters the head space 440 by licking the meniscus of the second ring. The curvature of the bubble 409 is determined by the size of the regulator passage 415, and thus the pressure adjustment is achieved by the same structure described above.

Referring to Fig. 18, the case where the head space 440 is positively pressurized due to the temperature rise is shown. In this case, air from the head space 440 pushes the ink of the second wet chamber 460 up the regulator passage and into the first wet chamber 450. As a result, the volume of the first ring 452 of ink held by the first wet chamber 450 is increased. However, the first wet chamber 450 is large enough to accommodate this increased ink volume so that the ink does not escape from the air inlet 403. Further, pressurized air from the head space 440 is discharged from the air inlet 403 by forming a bubble through the first ring 452 of the ink. In this way, ink losses due to day and night temperature differences or other temperature fluctuations are minimized or absent.

Evaporation represents a mechanism in which the liquid held by the first and second wet chambers is lost. But because the head space 440 is at The ink 104 body and the ink held in the wet chambers are in a state of being balanced, so that the water lost by evaporation is relatively quickly recovered by the moisture in the head space. If the ink chamber 401 is not empty, the head space 440 will always have a humidity approaching 100%.

The first and second wet chambers 450, 460 can have any suitable configuration if the first and second wet chambers 450, 460 can maintain a certain amount of liquid using surface tension. Referring to Figure 19, it can be seen in plan view that the first wet chamber 450 is generally circular (i.e., generally frustoconical) and the second wet chamber 460 is generally rectangular (i.e., generally frustoconical). It has been found experimentally that the second frustoconical second wet chamber 460 is particularly advantageous for avoiding ink loss.

The ink pressure regulator 400 described above has defined an ink cartridge for an ink jet print head. In another embodiment, the pressure regulating device including the first wet chamber 450, the regulator passage 415, and the second wet chamber 460 can be separately manufactured and then properly assembled to the ink cartridge.

It is recognized that the advantageous feature of pressure regulator 400 is that the pressure regulating assembly and the ink reservoir contained within the ink cartridge are fluidically isolated.

Improve the robustness of the bubble outlet exhaust into the head space

The pressure regulator 400 described above exhibits good pressure regulation. Again, the wet chambers 450, 460 ensure that the regulator passage 415 remains wet and ready for use, even after a typical day and night temperature cycle. But it is important that the pressure regulator maintains pressure regulation throughout its useful life (which can be several months). When subjected to severe temperature cycling and ink supply testing, it is still seen that some of the liquid is lost from the wet chambers 450, 460. Although these losses The loss is small, but if the pressure regulator is used for too long without replacement, the pressure regulator may still malfunction.

Evaporation via air inlet 403 is a potential cause of liquid loss. Another potential cause of liquid loss comes from bubbles that burst within the second wet chamber 460. Whenever a bubble bursts (during supply of ink from the ink outlet 402), a microscopic amount of liquid is removed from the wet chamber if the liquid is not drawn or recycled into the wet chamber.

Therefore, the inventors of the present invention have sought countermeasures that address these issues to improve the overall life and robustness of the pressure regulator. In an improved pressure regulator, the second wet chamber incorporates a liquid retaining configuration. There are two advantages to setting the liquid retention configuration. A first advantage is that the configuration increases the total liquid passage that is held within the wet chambers. The liquid volume can be increased by at least 5, 10, or 20 times compared to the pressure regulator 400, and any liquid loss that may occur within the system therefore does not result in a rapid failure of pressure regulation. A second advantage is that the liquid retaining configuration is typically constructed to ensure that any liquid generated by bubble bursts in the second wet chamber is captured and recovered into the wet system.

The liquid retaining configuration typically retains liquid by capillary action and may take the form of a hole (e.g., a groove) or a surface configuration (e.g., a groove) defined within the wall of the second wet chamber. In another embodiment, the liquid retaining configuration can take the form of a sponge.

Referring now to Figure 20, a particular embodiment of a pressure regulator 500 incorporating a desired body retention configuration 570 is shown. The pressure regulator includes an ink chamber 501 (which contains a reservoir of ink 104), and is used to supply ink to the column An ink outlet 502 of a print head (not shown). The same pressure adjustment as the pressure regulator 400 described above is obtained. Therefore, by the meniscus passing through the ink, bubbles having a predetermined Laplace pressure are separated from the bubble outlet 507 and exhausted into the head space 540. In normal use, the ink held by the wet system (in the form of first and second wet chambers 550, 560) and regulator channel 515 will be isolated from the body of ink 104 contained within chamber 501. Prior to installation in the printer (e.g., during shipping), all of the inlet and outlet ports within the chamber 501 can be plugged to prevent ink leakage.

As shown in FIG. 20, the top of the ink chamber 501 is defined by a laminated air introduction plate 510 that includes first and second planar layers 511, 512. In the pressure regulator 400 described above, the laminated air introduction plate 510 defines a side wall of the ink chamber 501. However, since the air introduction plate 510 defines the top of the ink chamber 501, the volume of the wet chamber can be maximized without affecting the amount of ink 104 that can be stored in the ink chamber. The air inlet plate 510 defining the top also facilitates installation within the printer.

The planar layers 511 and 512 of the air introduction plate 510 collectively define first and second wet chambers 550 and 560. The first and second wet chambers 550 and 560 are connected by a regulator passage 515. One end of the regulator passage 515 defines a bubble outlet 507, thus designing its critical dimensions to control the Laplace pressure of the bubble exiting the bubble outlet.

The first wet chamber 550 is in communication with the atmosphere via the air inlet 503, while the second wet chamber 560 is in communication with the head space 440 of the ink chamber 501 via the aperture 505.

The first and second wet chambers 550, 560 together maintain a constant volume of liquid (typically ink) and are used to ensure that the regulator passage 515 is always wet. Of course, it is important that when the regulator is required to perform the printing operation, the regulator passage 515 and the bubble outlet 507 are never dried, otherwise the air can simply flow into the head space 540 and the pressure regulator fails.

Ink can be transported between the first and second wet chambers 550, 560 via a regulator passage 515. Therefore, the amount of ink held in each of the first and second wet chambers 550, 560 can be based on whether the bubble adjuster 500 supplies ink to the connected print head during printing, or whether the bubble regulator is Idle and change.

Because it is similar to the pressure regulator 400, it can be appreciated that the pressure regulator 500 achieves pressure regulation in exactly the same manner. Again, ink transfer between wet chambers 550 and 560 occurs similarly. For a detailed description of how this ink transfer occurs, reference is made to Figures 16 through 18 above and their corresponding descriptions.

Although the pressure regulator 400 relies only on the inclined side walls of the wet chambers 450, 460 to hold the liquid therein, the pressure regulator 500 has an elongated second wet chamber 560 that incorporates the elongated second wet chamber 560 Liquid retention structure 570. The liquid retaining formation 570 is in fluid communication with the liquid within the regulator passage 515 and thus provides a reservoir for replenishing any liquid lost by the regulator passage due to, for example, evaporation through the air inlet 503. Further, when the ink is supplied through the ink outlet 502, the bubble that is expected to leave the bubble outlet 507 bursts in the second wet chamber 560. The microscopic amount of ink produced by the bursting of the bubble is received by the liquid holding structure 570, which remains Construction 570 extends the length of second wet chamber 560. Therefore, this ink is drawn and recovered to ensure that the regulator passage 515 does not dry out.

If the liquid retention configuration 570 performs the function of providing fluid communication between the liquid reservoir and the regulator channel 515, the liquid retention configuration 570 can take many different forms. The liquid retaining formation 570 typically retains the liquid by capillary action.

21 through 23 are top views of layer 512, each of which shows a different form of liquid retaining configuration 570.

In FIG. 21, the liquid retaining formation 570 includes a plurality of holes 871 through the layer 512 that communicate into the head space 540 of the ink chamber 504 (see FIG. 20). Each hole 571 is an elongated slot having a small width dimension sufficient to retain liquid by capillary action. The liquid confined within such slots 571 is in communication with the regulator passage 515.

In FIG. 22, liquid retaining formation 570 includes a plurality of pockets or grooves 572 defined within the surface of layer 512. Each groove 572 holds the liquid by capillary action and is in communication with the regulator passage 515.

In Figure 23, the liquid retaining formation 570 comprises a sponge 573 that retains the liquid by capillary action. The sponge can be disposed within a complementary recess of layer 512. In another embodiment, the sponge 573 can be supported in a complementary groove that is positioned within the layer 512 such that one surface of the sponge 573 contacts the head space 540. An advantage of this latter configuration is that the sponge 573 can confine the saturated ink vapor within the head space 540 and thus minimize the likelihood of the sponge drying out. The sponge 573 can also absorb ink when the chamber 501 is tilted or tipped over (e.g., during transport). Similarly, connect into the head empty The slot 571 of the above 540 performs the same function.

Those skilled in the art will recognize other forms of liquid retaining construction that retain liquid by capillary action. Basically, any configuration with curved features is suitable.

Due to the simplicity and low cost manufacturing of the pressure regulator 500, it is constructed as a replaceable ink cartridge for an ink jet printer. Therefore, the pressure regulator is also replaced each time the crucible is replaced. The advantage of this design is that since the pressure regulator 500 is periodically replaced during the life of the printer, the pressure regulator 500 is prevented from being contaminated or blocked for a long time.

It is to be understood that the invention has been described by way of example only, and modifications may be The scope of the invention is defined by the appended claims.

1‧‧‧匣

2‧‧‧Foaming

3‧‧‧Export

4‧‧‧sucking section

5‧‧‧Unsaturated section

6‧‧‧ arrows (capillary action)

7‧‧‧Air winding path

100‧‧‧pressure regulator

101‧‧‧Ink chamber

102‧‧‧Ink outlet

103‧‧‧Air inlet

104‧‧‧Ink

105‧‧‧Print head

106‧‧‧Ink line

107‧‧‧ bubble exit

108‧‧‧Air passage

109‧‧‧ bubbles

110‧‧‧ slots

111‧‧‧Shards

200‧‧‧pressure regulator

201‧‧‧Ink chamber

202‧‧‧Ink outlet

203‧‧‧Air inlet

207‧‧‧ bubble outlet

208‧‧‧Air passage

209‧‧‧ bubbles

210‧‧‧Air introduction board

211‧‧‧ first (planar) layer

212‧‧‧second (planar) layer

213‧‧‧Air inlet opening

214‧‧‧Elongated recess

216‧‧‧Circular recess

217‧‧‧cell opening

218‧‧‧Restriction

219‧‧‧Pressure relief valve

220‧‧‧ bubble exit area

221‧‧‧ first side

222‧‧‧ second side

230‧‧‧ trench

231‧‧‧ inside

240‧‧‧ (ink chamber) head space

241‧‧‧(Ink) head space

250‧‧‧Air introduction board

251‧‧‧ first floor

252‧‧‧Air inlet opening

253‧‧‧ second floor

254‧‧‧ bubble outlet opening

256‧‧‧Air passage opening

280‧‧‧Ink 匣

281‧‧‧Ink connector

282‧‧‧Ink supply埠

283‧‧‧Ink inlet埠

285‧‧‧Isostatic connector

286‧‧‧etc.

287‧‧‧etc.

300‧‧‧pressure regulator

301‧‧‧Ink chamber

302‧‧‧Ink outlet

303‧‧‧Air inlet

304‧‧‧Ink column

305‧‧‧ bubble holes

307‧‧‧ bubble outlet

308‧‧‧Air passage

309‧‧‧ bubble

310‧‧‧Air introduction board

311‧‧‧ first (planar) layer

312‧‧‧second (planar) layer

315‧‧‧Capillary channel

316‧‧‧Mini entrance

400‧‧‧pressure regulator

401‧‧‧Ink chamber

402‧‧‧Ink outlet

403‧‧‧Air inlet

405‧‧‧ bubble holes

407‧‧‧ bubble outlet

409‧‧‧ bubbles

410‧‧‧Air introduction board

411‧‧‧ first (planar) layer

412‧‧‧second (planar) layer

415‧‧‧Regulator channel

440‧‧‧ head space

450‧‧‧First wet chamber

451‧‧‧ sloping wall

452‧‧‧ first ring

460‧‧‧Second wet chamber

461‧‧‧ sloping wall

462‧‧‧ second ring

463‧‧‧Moon Moon

500‧‧‧pressure regulator

501‧‧‧Ink chamber

502‧‧‧Ink outlet

503‧‧‧Air inlet

505‧‧‧ hole

507‧‧‧ bubble outlet

510‧‧‧Air inlet board

511‧‧‧ first (planar) layer

512‧‧‧second (planar) layer

515‧‧‧Regulator channel

540‧‧‧ head space

550‧‧‧First wet chamber

560‧‧‧Second wet chamber

570‧‧‧Liquid retention structure

571‧‧‧ hole

572‧‧‧ditch

573‧‧‧Sponge

L‧‧‧Length size

W‧‧‧Width size

Alternative embodiments of the invention (by way of example only) are described with reference to the drawings. 1 is a schematic side cross-sectional view of a pressure regulator having a needle-shaped bubble outlet of the present invention; FIG. 2 is an enlarged view of the bubble outlet shown in FIG. 1; FIG. 3A is a schematic perspective view of a groove-shaped bubble outlet; Figure 3 is a schematic side cross-sectional view of the pressure regulator of the present invention having a trough-like bubble outlet; Figure 5 is an enlarged plan view of the bubble outlet shown in Figure 4; Figure 6 is an exploded perspective view of the air introduction plate of Figure 4; Figure 7 is a perspective view of another embodiment air introduction plate having a protective gutter; Figure 8 is an exploded perspective view of another embodiment three-layer air introduction plate; Figure 9 is a schematic side cross-sectional view of the pressure regulator of Figure 4 connected to a separate ink cartridge; Figure 10 is a schematic side cross-sectional view of a pressure regulator having a bubble outlet, the bubble outlet being provided to cause bubbles to break into the head space and capillary The ink is supplied to the bubble outlet; FIG. 11 is an enlarged view of the bubble outlet shown in FIG. 10 during printing; FIG. 12 is an enlarged view of the bubble outlet shown in FIG. 10 during idle; FIG. 13 is the bubble shown in FIG. FIG. 14 is an exploded perspective view of the air introduction plate of FIG. 10; FIG. 15 is an exploded perspective view of the air introduction plate with the regulator passage; FIG. A schematic side cross-sectional view of the pressure regulator; Fig. 16 is an enlarged view of the regulator passage shown in Fig. 15 during idle; Fig. 17 is an enlarged view of the regulator passage shown in Fig. 15 during printing; Fig. 18 is Fig. Regulator shown Road enlarged view of the head space is positively pressurized; Figure 19 is a cutaway perspective view of the pressure regulator of Figure 15; Figure 20 is a schematic side cross-sectional view of a pressure regulator having a wet system incorporating a liquid retaining configuration; Figure 21 is a top view of the liquid retaining configuration; Figure 22 is a top plan view of another embodiment of the liquid retaining structure; Figure 23 is a top plan view of still another embodiment of the liquid retaining structure; and Figure 24 is a schematic side cross-sectional view of a conventional ink cartridge incorporating foaming Insert.

104‧‧‧Ink

500‧‧‧pressure regulator

501‧‧‧Ink chamber

502‧‧‧Ink outlet

503‧‧‧Air inlet

505‧‧‧ hole

507‧‧‧ bubble outlet

510‧‧‧Air inlet board

511‧‧‧ first (planar) layer

512‧‧‧second (planar) layer

515‧‧‧Regulator channel

540‧‧‧ head space

550‧‧‧First wet chamber

560‧‧‧Second wet chamber

570‧‧‧Liquid retention structure

Claims (20)

An ink pressure regulator (500) for regulating hydrostatic pressure of ink supplied to an inkjet print head, the regulator comprising: an ink chamber (501) for storing ink, the ink chamber having An ink outlet (502) fluidly connected to the printhead via an ink line; and an air inlet (503); wherein the regulator passage (515) has less than a top (510) of the ink chamber a critical depth dimension of 200 microns as defined in the regulator channel having a first end in fluid communication with the air inlet (505) and a second end in fluid communication with the head space (540) of the ink chamber, a second end defining a bubble outlet (507); and a wet system defined in the top (510) for maintaining at least some of the liquid within the regulator passage; the wet system comprising: a first wet chamber (550), Connected to the first end; a second wet chamber (560) coupled to the second end; and a liquid retaining formation (570) disposed in at least one of the wet chambers such that the regulator passage ( 515), the first wet chamber (550), the second wet chamber (560), and the liquid holding structure (570), all in fluid communication with each other. The ink pressure regulator of claim 1, wherein the liquid retaining structure is constructed such that liquid from the bursting bubble is drawn by the liquid retaining structure. An ink pressure regulator as described in claim 2, Wherein the second wet chamber is elongate and the liquid retaining formation extends along the length of the second wet chamber. The ink pressure regulator of claim 1, wherein the liquid retaining structure is in spatial communication with the head. The ink pressure regulator of claim 1, wherein the liquid retaining structure retains the liquid by capillary action. The ink pressure regulator of claim 4, wherein the liquid retaining formation is defined by one or more liquid retaining holes defined in the wall of the second wet chamber, the liquids maintaining hole communication Enter the head space. The ink pressure regulator of claim 5, wherein the liquid retaining formation is defined by a plurality of grooves defined in the wall of the second wet chamber. The ink pressure regulator of claim 5, wherein the liquid retaining structure is a sponge. The ink pressure regulator of claim 5, wherein the liquid retaining formation comprises one or more liquid retaining surface features defined within a wall of the second wet chamber. The ink pressure regulator of claim 7, wherein the liquid retaining formation comprises a plurality of grooves defined in a wall of the second wet chamber. The ink pressure regulator of claim 1, wherein the first wet chamber is connected to the atmosphere via the air inlet. An ink pressure regulator as described in claim 1 of the patent application, Wherein the second wet chamber has a hole that communicates into the head space. The ink pressure regulator of claim 1, wherein the wet chamber, the regulator passage, and the liquid retaining configuration together maintain a substantially constant amount of liquid. The ink pressure regulator of claim 1, wherein each wet chamber is constructed such that liquid is secured into an edge region of the wet chamber, the edge regions being coupled to the regulator passage. The ink pressure regulator of claim 14, wherein each of the wet chambers is substantially beveled such that the edge regions comprise at least two chamber walls that meet at an acute angle. The ink pressure regulator of claim 1, wherein the forward pressurized head space forces liquid to be transferred from the second wet chamber to the first wet chamber during idle periods. The ink pressure regulator of claim 15, wherein the positively pressurized air in the head space first passes through the liquid and escapes via the air inlet. The ink pressure regulator of claim 1, wherein the liquid is ink. The ink pressure regulator of claim 1, wherein the air inlet, the regulator passage, and the wet system are disposed at a top of the ink chamber. The ink pressure regulator of claim 1, wherein the pressure regulator defines an ink cartridge for an inkjet printer.