JPH07329313A - Medium for ink transport system - Google Patents

Abstract

PURPOSE: To eliminate the problem of ink clogging at cleaning by providing a medium holding a proper amt. of liquid ink to at least a part of a chamber and providing a cleaning member applying capillary force larger than that of the medium and containing no residual foam surfactant to an outlet port. CONSTITUTION: A cartridge 10 where a printing head and an ink feeder are combined has a chamber 13 and is provided with a housing 12, having a ventilation port 14 and an outlet port 16 formed thereto and houses an ink storage medium 18 in the chamber 13. A heat sink 24 and a cover 28 having an opening 29 enabling ventilation in the housing 12 through the ventilation port 14 are provided to one end of the housing 12. In this case, a sweeping member 20 comprising a substance providing capillary pressure between the ink storage medium 18 and the outlet port 16 is provided in the housing 16. The sweeping member 20 is formed from fine pore fully open cell polyester polyurethane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an ink transport system,
More specifically, it relates to media for ink transport and filtration.

[0002]

BACKGROUND OF THE INVENTION Existing ink delivery systems provide and retain high quality prints, mostly with good optical density, due to the decomposition and degradation of existing foam and felt ink media used. It's not something you can do. The removed fibers, particles, and debris are believed to be major contributors to the ink channel obstruction. Ink channel blockage occurs due to ink drop outs, missing jets, exploding jets, and other jet problems. Wire meshes and filters have been used between the ink medium and the nozzle to filter out particles, but these filters are difficult to filter because particles, debris, or fibers that are difficult to filter pass through. It does not perform filtration or blockage efficiently. Also, these filters can become clogged with particles, debris, or fibers from non-filtering foams and felts. Once the particles, debris, or fibers have accumulated on the filter, it is difficult to clean their surface. Clogging causes delays in refilling the printhead with ink and problems with air uptake, which results in slow print speeds and poor ink jet print quality.

Melamine foams are often used in ink delivery systems, as disclosed in US patent application Ser. No. 07 / 885,704. However, although melamine foam has the advantages of low impedance and high efficiency, it can cause fouling. Foam debris can break during use and melamine foam can produce melamine dust. Therefore, the use of melamine foam in ink delivery systems requires the use of filters. Melamine dust is difficult to remove with a filter,
The filter surface is difficult to clean and can also become clogged through the ink channels, causing the problems associated with the ink blocks described above. Therefore, the melamine foam must be pre-cleaned before use. In addition to this, in actual use,
Finer filters, eg, 9 micron filters, are needed to properly filter out particles associated with melamine foam. Impedance increases because melamine foam requires finer filters. The reticulated foam is also not clean and dirty. During processing, multiple cells may explode.
reaction) to destroy free material (free materia
l) is present in the form. Therefore, the reticulated foam must also be pre-cleaned to filter out this free material. However, pre-cleaning does not filter out all free material and, during use, further destruction occurs, producing more particles and debris. As a result, the above-mentioned problems associated with ink blockage occur.

Foams other than the melamine foams currently used in ink delivery systems are made according to the surfactant-forming foam formation process. In order to make the foam usable in the ink delivery system, an expensive cleaning process is required to remove the non-water soluble surfactants from the foam. Currently, a freon cleaning wash is used to clean the foam. However, this cleaning process and the residue left after this cleaning process must be properly arranged so as not to adversely affect the environment.

[0005]

SUMMARY OF THE INVENTION Ink delivery and filtration media have low impedance and are uncontaminated (substantially free of loose particles, debris, or fibers from the time they were originally created or through use in ink delivery systems. It does not have), has a low compression set, and is substantially free of surfactant. Moreover, some media are needed for use with the scavenging members described in more detail herein. The present invention includes an ink delivery and filtration medium for an ink delivery system. This ink transport / filtration medium has a high concentration, fine pores, fully open cell polyester polyurethane. Preferably, the foam raw material is of the trade name "UL
Fo of Eddystone, PA issued in "TRA FINE"
amex is available and the felt version of the form is lllbruck,
Minneapolis, MN, USA is available. In one embodiment of the invention, this ink medium is used for the scavenging member. Other objects, advantages and features of the present invention will become apparent from the following more detailed description, which discloses more preferred embodiments of the invention in connection with the drawings.

[0006]

DETAILED DESCRIPTION OF THE INVENTION For purposes of illustrating the invention, the following description discloses the medium according to the invention as disclosed in pending US patent application Ser. No. 07 / 885,704, which is hereby incorporated by reference. It is incorporated into the scavenging member. However, it is within the scope of the invention to provide the media with any ink transport system applicable according to the invention. FIG. 3 illustrates a thermal printer in which the printhead and the ink supply are combined into a single container, such as a cartridge 10.
FIG. 3 is an elevational view of an ink jet printer type. The main part of the cartridge 10 is an ink supply device including other parts forming the actual print head 100. In this embodiment of the invention, cartridge 10 is located in a thermal ink jet printing device in which cartridge 10 is moved along cartridge 200 in the following manner. That is, the printhead 100 moving relative to the sheet 210 prints characters on the sheet 210 as the cartridge 10 moves across the sheet in a manner somewhat similar to a typewriter. The size of printhead 100 in the illustrated example is such that each path of the cartridge along sheet 210 causes printhead 100 to print one
It is large enough to print one line. However, the text lines need not conform to the swaths of the copy cartridge 10. Using each print row of the cartridge 10, the sheet 21
Any number of passes of the printhead 100 can be used to slide 0 in the direction of arrow 205 (by means not shown) to print or image text on sheet 210. Cartridge 10 also includes the means indicated by 220. By this means, digital image data can be input to the various heating members 110 of the printhead 100 to print the desired image. These means 220 may comprise, for example, plug means. These plug means are incorporated into the cartridge 10 to accept a bus or cable from the data processing portion of the device and allow a working connection to the heating elements of the printhead 100.

FIG. 1 is a partial elevational view of cartridge 10. The cartridge 10 comprises a main part in the form of a housing 12. The housing 12 is generally made of a metered but durable plastic. The housing 12 forms a chamber 13 for storing liquid ink, and further has a ventilation port 14 formed therein. The ventilation port 14 is open to the atmosphere and the outlet port 16.
The end of the outlet port 16 (shown in cutaway in FIG. 1) is the ink jet printhead 100, specifically the ink supply manifold. The ink saturation medium shown in accordance with one embodiment of the present invention comprises three separate portions, labeled 18. The ink saturation portion 18 occupies most of the chamber 13 of the housing 12. FIG. 2 is an exploded view of the cartridge 10 showing how the various members of the cartridge 10 are formed into a small customer replaceable device. Another portion of the cartridge 10 useful in certain embodiments of the present invention includes a heat sink 24 and a cover 28 with an opening 29 that allows ventilation inside the housing 12 through the ventilation port 14. Practical designs typically include space for on-board circuitry to selectively activate the heating elements of printhead 100.

Also shown in FIGS. 1 and 2 is the ventilation port 14 (coupled to external air pressure) to the housing 12.
A tube 30 extending through an opening in each portion of the ink storage medium 18 for pressure balancing to the center of the interior. For purposes of illustration and in accordance with one embodiment of the present invention, ink storage medium 18 (shown as three material parts) is in the form of a polyester fiber needle felt. Needle-type felts are formed of fibers that are physically entangled by the action of a needle loom, for example, but these fibers can also be entangled by soaking or steam heating. According to one embodiment of the invention, the needle felt has a density of 0.06-0.13 grams per cubic centimeter. The optimum density of this polyester needle-type felt ink storage medium 18 has been found to be 0.095 grams per cubic centimeter. This optimum density provides the most useful volume that is efficient at holding liquid ink. Ink storage medium 18 is described in more detail in US patent application Ser. No. 07 / 885,704. In summary, the ink storage medium 18 is packed in the closed structure of the housing 12 in such a way that the felt exerts an ideal contact and pressure on the inner wall. In one embodiment of the invention, the ink storage media 18 are each ½
It is created by stacking three layers of inch (about 1.27 cm) needle felt and packing them inside the housing 12.

The inside of the housing 12 is also the scavenging member 2
High capillary pressure, shown as 0
Is a member formed of a substance that provides. Scavenging member 20
Is a relatively small member that acts as a porous capillary linkage between the ink storage medium 18 and the outlet port 16 leading to the manifold of the printhead 100. In the preferred embodiment of the present invention, the scavenging member 20 is microporous and is made from a microporous, fully open cell polyester polyurethane made with a proprietary additive. Fod from Eddystone, PA under the trade name "ULTRAFINE"
Amex is available and a felted version of a foam suitable for use in a scavenger is available, for example, through lllbruck, Minneapolis, USA, MN. Improver,
The ULTRA FINE functions as an ink transport-filtration medium used in the scavenging member 20. Especially ULTRA
FINE can be easily compressed to a certain density and absorbency. According to a more preferred embodiment of the present invention, the ULT
RAFINE is felt (compressed using heat and pressure) by 50% in the intended ink flow direction. For example, in one embodiment, ULTRA FINE is cut into 9 mm thick blocks. ULTRA FINE blocks are compressed to 4 1/2 mm using heat and pressure, which doubles the density. With increased density, tubule action is improved and increased. Furthermore, once ULTRA F
Once the INE is finally compressed to the desired density, no further compression is required once the scavenging member is placed in the cartridge 10.

ULTRA FINE has a low compression set, which is the ULTRA FIN.
Make E dimensionally stable. ULTRA when compressed
Fine bounces back to its original position. For example, UL
TRA FINE is, for example, ink or ink storage medium 1
Even when compressed for a long time under pressure from 8, it is elastic enough to return to its original length. Especially ULT
The RA FINE scavenging member is capable of elastically returning to within 2% of its original size. Further, the ULTRA FINE scavenger does not substantially spread when ink is applied. The dimensional stability of the scavenging member is especially important in ink delivery systems. Because
This is because if it fails to withstand the pressure between the filter and the ink fountain, air leakage may occur. Air leakage occurs when lower resistance air is pulled into the scavenging member instead of ink. Once the air has entered the scavenging member, it is difficult to recover the printhead and inject. Since surfactants react with the ink, foams made with surfactants must be cleaned with Freon washes to remove the surfactant before use. ULTRA F
INE is substantially free of surfactants and therefore does not require expensive freon cleaning.

ULTRA FINE is also very clean. In the ULTRA FINE flow-through test,
Particles that are negligible are emitted. These negligible particles are no larger than 5 microns and are too small to cause ink clogging. In addition, ULTRA FI
Since the NE material is not fragile and has a low elastic modulus, ULTRA FINE does not break down and release particles or debris during use. In addition, ULTRA F
INE has good clickability and punch performance due to the low compression set of ULTRA FINE.
(punchability) (the ability of the cutting edge to return to its original shape after being cut). ULTRA FINE
When the edges of are cut to form the scavenging member 20, these edges are reliably restored to their original size. FIG. 4 is a characteristic comparison diagram comparing optimization goals for a scavenger with ULTRA FINE with 11 micron filters and melamine foam with 11 and 9 micron filters. Ink compatibility, filtration, original cleanliness (cleanlin
Properties such as ess), punch performance, compression set, expansion upon wetting, ink transport, steady state impedance, and chemical reactivity are compared for illustration. The ULTRA FINE scavenger with the 11 micron filter has a lower impedance than the melamine scavenger with the 11 micron filter. In addition, ULTRA FI
The NE scavenger has a substantially lower impedance than the melamine scavenger with the 9 micron filter. 1
A melamine scavenging member with a 1 micron filter is shown for purposes of illustration, but such a filter is not used in practice. This is because melamine foam is a clean foam and the 11 micron filter does not adequately filter out particles. For practical use, the melamine scavenger requires a 9 micron filter.

Optimal filtration-particle coagulation when the scavenger is used in a cartridge.
unt) is 0 fiber. U as shown
LTRA FINE is capable of detecting a particle count of 0 in an ink delivery system. Furthermore,
The incoming cleanliness of ULTRA FINE foam before it is cleaned or vacuumed to remove particles are superior to that of melamine. ULTRA FINE does not require cleaning to remove particles prior to use, but with melamine. The scavenging member 20 is preferably a filter cloth 2
Including 2. A more preferred material for filter 22 is monofilament polyester screening fiber as described in more detail in US Pat. No. 07 / 885,704. The filter cloth 22 is laminated to ULTRA FINE without the use of an adhesive matrix. Therefore, the filtering is a single step ULTRA FINE
Attached to. When ULTRAFINE is compressed to achieve the desired density, the cloth 22 is simultaneously ULTRA.
Stacked on FINE.

The high capillary force provided by the filter cloth 22 causes the filter cloth 22 against the scavenging member 20.
Flatness (no wrinkles or protrusions), exit port 16
The compression of the scavenging member 20 against and the saturation of the scavenging member 20 form an ink film between the filter 22 and the output port 16. This film serves to block the air from the outlet port 16. In FIG. 1, the ink storage medium 18
A portion of the outer surface of the ink storage medium appears to be in contact with the scavenging member 20, while another portion of the surface of the ink storage medium is open between the ink storage medium 18 and the inner wall of the housing 12.
It is exposed in the space 15. A single chamber 13 is formed to allow ink to flow to or from the ink storage medium 18, or to or from the scavenging member 20, or to or from the free space within chamber 13. is there. That is, there is no perfect internal barrier to the flow of ink in chamber 13. This configuration helps maintain the back pressure of the liquid ink to a manageable extent while the cartridge slowly drains the liquid ink. However, ink transfer through the ink storage medium 18 is not fast enough to provide a continuous supply of ink to the printhead 100 during high demand rates. Moreover, the felt of the ink storage medium 18 does not provide the necessary seal to allow continuous, air-free, ink flow through the outlet port 16. Scavenging member 20
As described in detail below, serves as an ink reservoir supplying a sufficient amount of ink in the absence of air even during high demand rates.

General commercial thermal ink jet
In the printing apparatus, the print head is moved in multiple rows across the sheet and the time to print 8 inches is approximately 0.5 seconds. The cartridge 10 is
It takes about 0.1 seconds to make a turn between printed rows. The scavenging member 20 tends to become unsaturated while printing a row as the ink is placed on the sheet. The time between print runs is typically the "recovery" time during which the scavenging member 20 is allowed to saturate again, thereby returning to equilibrium back pressure. According to one embodiment of the invention, the ink storage medium 18 is initially filled with 68 cubic centimeters of liquid ink. At least 5 for printing purposes while the back pressure of the cartridge is within the usable range.
It is desirable to get 3 cubic centimeters. Scavenging member 2
A typical volume of 0 is 2 cubic centimeters. To print a typical 8 inch (20.3 cm) row when printing a document, the scavenging member 20 has 2.
Up to 5% may become unsaturated in 0.5 seconds. This unsaturation causes an increase in back pressure on printhead 100. This principle can best be imagined by analyzing common sponges.
In other words, squeezing a certain amount of liquid from a saturated sponge will squeeze the same amount of liquid from an unsaturated sponge, even if the required amount of liquid is present in the sponge that has dried almost. Is easier than that. Unsaturation causes an increase in backpressure in either absorbent medium, so that backpressure increases during the printing of a single row of significant density across the sheet.

However, while the desaturation of the scavenging member 20 increases back pressure in the printhead 100, this increased back pressure from the scavenging member 20 acts in the other direction as well. That is, the unsaturation of the scavenging member 20 also causes a negative pressure on the ink storage medium 18, causing a certain amount of ink to be transferred from the ink storage medium 18 to the scavenging member 20, thereby causing the scavenging member 20 to re-emerge. It saturates and reduces its back pressure. The combination of the ink storage medium 18 and the scavenging member 20 functions as a device for stabilizing the back pressure in the print head 100 when the ink supply of the ink storage medium 18 is reduced. 5 to 8 show a peristaltic ink transport test showing the performance of the ink jet cartridge 10.
k delivery test). Figure 5 shows ULTRAF
5 shows back pressure at the printhead of a cartridge with a scavenger made of INE foam. FIG. 5 shows that the back pressure held by the print head 100 is
It shows that most of the ink level of 0 is kept within the usable range. In FIG. 5, the X-axis shows the volume of ink conveyed through the printhead 100 (ie, when the cartridge is completely emptied), while the Y-axis shows a backpressure at the printhead that is comparable to a millimeter of liquid ink in water. It is displayed in millimeters. The graph of FIG. 5 shows the three lines described below in the general context of a printed document in an apparatus such as that shown in FIG. That is, a solid line that is the "static capillary pressure" of the cartridge in the printhead and a solid line that shows the back pressure at a given instant created during the printing of individual print rows at both ends of the sheet. A dotted line on the top and a vertical line showing the end of ink supply when only air is being removed from the cartridge. Back pressure is maintained in the best range, approximately 24 mm to 152 mm, until such time as about 50 cc of ink is delivered. In the more preferred embodiment, the cartridge 10 is originally loaded with 68 cc of ink so that only a small amount of ink is wasted due to inefficient back pressure.

FIG. 6 is a partial detailed view of the graph of FIG.
1 illustrates a typical movement of back pressure in the kantridge 10 during continuous or substantially continuous use. Figure 3
The type of thermal ink jet printer shown in
The cartridge 10 reciprocates in a series of parallel print rows across the copy sheet such that the printhead 100 prints an image on the copy sheet 210.
Each print row on either side of copy sheet 210 typically lasts 0.5 seconds, while the turnaround time at the end of each print row is approximately 0.1 seconds (in a typical embodiment, printhead 100). Ejects ink onto the copy sheet as it moves the cartridge 10 in either direction). As described above, liquid ink is removed from the cartridge 10 during the printing of a print train and the scavenging member 20 is substantially re-saturated during the instantaneous redirection of the cartridge 10. If the scavenging member 20 (and, if expanded, the entire ink supply, including the ink storage medium 18) becomes slightly unsaturated, the back pressure increases. The cyclic repetition of desaturation and re-saturation of the scavenging member 10 during substantially continuous use of the cartridge translates into a cyclic pattern of increasing and decreasing back pressure as seen in FIG. .

In FIG. 6, the fine dotted lines forming the saw blade in the increasing portion a and the decreasing portion b are the solid static capillary back pressure and the localized local area indicated by the larger dotted line seen in FIG. The movement of the back pressure between the maximum point and the actual continuous time is shown. For each saw blade, the instantaneous increase indicated by portion a represents the increase in back pressure as the ink supply system applies ink during printing of the print train, Relatively quick descending part b
Indicates that the scavenging member 20 re-saturated relatively quickly during the turnaround time. In addition to unsaturation of the ink storage medium 18, another source of back pressure in the cartridge 10 is the "impedance" of the ink flow through the various elements of the cartridge 10. This impedance is
It is caused by various sheer forces between the ink storage medium 18, the scavenging member 20, and other parts. For example, pure force exists at a fine level inside the felt of the ink storage medium 18 and the foam of the scavenging member 20. 7 and 8 are graphs of a peristaltic ink transport test similar to the graph of FIG. FIG. 7 shows a melamine foam with an 11 micron filter and FIG. 8 shows a melamine foam with a 9 micron filter. Comparing FIG. 5 and FIG. 7 (both 11 micron filters), the cartridge with ULTRA FINE (FIG. 5 above) had the best range when 50 cc of ink was removed from the cartridge, approximately 152 mm.
(Or the end of the cartridge life) is reached. In contrast, melamine foam (FIG. 7) arrives outside of it in a shorter time, especially after removing 48 cc of ink. Further, the particular embodiment of the melamine foam shown in FIG. 8 reaches outside of this range after only 34 cc of ink has been removed. Furthermore,
As shown in FIG. 5, ULTRA FINE
It has a flatter line than the lines shown in FIGS. 7 and 8 for melamine. ULTRA FINE has a flatter line and therefore behaves more stably than melamine foam throughout its life. Therefore, ULTRA FINE not only provides the desired backpressure range at the printhead in a consistent manner throughout the life of the copy cartridge, but also during continuous use of the copy cartridge, Holds a relatively constant amount of back pressure.

FIG. 9 is a test obtained from the ULTRA FINE performance test in a production cartridge designed to determine whether ULTRA FINE changes the average life of the cartridge (ie, the number of pages printed). It shows data. In contrast to the peristaltic pump test in Figures 5-8, this test incorporates the actual print pose. This test includes a continuous run test that produces approximately 1000 pages of a given test image per day. 39 cartridges with ULTRA FINE with 11 micron filter (20 pilot wait time portion and 19 production wait time portion as shown in FIG. 9) and 9 micron Seventeen cartridges with melamine with a filter are tested to the end of their life. ULTRA FINE and melamine foam have been tested for practical use and, therefore, as described above, 11
The melamine cartridge is 9 micron because the micron filter is not suitable for filtering particles and debris.
Used a filter. ULTRA FINE cartridges average 6 as seen in "Ink Weight Loss"
The melamine cartridge output 59.40 grams of ink, whereas the ink output of 1.06 grams. Therefore, the ULTRA FINE cartridge outputs about 1.66 grams more. "Number of pages"
The ULTRA FINE cartridge printed an average of 1261 pages, while the melamine foam cartridge printed 1234 pages.

While this invention has been described in terms of a particular device, many modifications and variations will be apparent to those of ordinary skill in the art. Therefore, such changes and modifications are considered to be included in the intended scope of the claims.

[Brief description of drawings]

FIG. 1 is a partial elevation view of a cartridge incorporating the present invention.

FIG. 2 is an exploded view of the cartridge shown in FIG. 1 incorporating the present invention.

FIG. 3 is a perspective view of a thermal ink jet printing apparatus.

FIG. 4 is a diagram comparing characteristics of filter foams including a medium according to the present invention.

FIG. 5 is a graph of a peristaltic ink transport test showing the back pressure of liquid ink as a function of the amount of ink in the cartridge when using the ink transport-filtration media of the present invention.

FIG. 6 is a detail of the graph of FIG.

FIG. 7 is a graph similar to FIG. 5 showing back pressure for an ink cartridge using a melamine foam with an 11 micron filter.

FIG. 8 is a graph similar to FIG. 5 showing back pressure for an ink cartridge using melamine foam with a 9 micron filter.

FIG. 9 shows test data generated by life cycle testing of ink cartridges using different ink transport-filtration media.

[Explanation of Codes] 10 Cartridge 12 Housing 13 Chamber 14 Ventilation Port 16 Outlet Port 18 Ink Storage Medium 20 Scavenging Member 100 Printhead 210 Sheet

Claims (2)

[Claims] 1. A system for supplying liquid ink to a thermal ink jet printing apparatus, comprising: a housing forming a chamber having a ventilation port and an outlet port; A medium suitable for holding liquid ink and disposed across the outlet port to provide a capillary force greater than that of the medium and substantially free of residual foam surfactant and loose particles. A removal member, and a system. 2. A system for supplying liquid ink to a thermal ink jet printing device, the housing forming a chamber having a ventilation port and an outlet port, occupying at least a portion of the chamber, A medium suitable for holding liquid ink, and an ink delivery and filtration medium comprising a high density, microporous, fully open cell polyester polyurethane disposed across the outlet port. System to do.