JPH04308760A - Ink-jet printing device - Google Patents

Abstract

PURPOSE: To improve the printing speed and printing sharpness of an ink jet printing machine. CONSTITUTION: An ink jet printing apparatus is equipped with a printing head 42 and the printing head 42 is equipped with a plurality of separately operable ink jet printing elements 40. The ink jet printing apparatus is equipped with an apparatus for feeding base material to be printed such as paper or the like in relation relatively separated from the printing head 42. The printing elements 40 are obliquely arranged in six rows and respective rows are equipped with 400 printing elements.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates generally to inkjet printing devices.

0002

BACKGROUND OF THE INVENTION There are numerous patent documents regarding ink jet printing machines. Generally speaking, there are two basic types of inkjet printers, one being a continuous jetting inkjet printer and the other being a rapid firing inkjet printer.

Although conventional inkjet printers are extremely cost competitive compared to other types of high quality printers, they have a major drawback in printing speed compared to laser printers. The shortcomings in printing speed are basically:
This results from the use of moving printheads with relatively low linear density inkjet nozzles.

[0004] Typical quick-response ink type (ink-on-demand type) thermal bubble ink jet print heads and piezoelectric type ink jet print heads are made of glass,
A generally flat base of quartz or metal is used on which ink channels, generation chambers and capillaries are formed by photoimaging or etching techniques. This technology imposes inherent limitations on the linear density of inkjet nozzles on the base.

[0005]

SUMMARY OF THE INVENTION The present invention seeks to provide an improved ink jet printing machine that overcomes the drawbacks of the prior art as described above.

[0006]

SUMMARY OF THE INVENTION Accordingly, in accordance with a preferred embodiment of the present invention, there is provided a stationary printhead assembly having a plurality of separately operable inkjet printing modules; An inkjet printing apparatus is provided comprising, in operatively spaced relationship with the printhead assembly, an apparatus for transporting a substrate for printing.

Also in accordance with a preferred embodiment of the present invention, there is provided a printhead assembly having a plurality of independently and separately operable inkjet printing modules, and a substrate for printing by said inkjet printing modules. A ready-to-read inkjet printing device is provided that includes an assembly and a relative transport device.

[0008] The number of inkjet printing modules is 10.
Preferably it exceeds 0.

Embodiments of the present invention also include a printhead assembly having a plurality of separately operable inkjet printing modules extending over the entire writing dimension of a page; An inkjet printing device is provided comprising the above printhead assembly and a relative transport device.

Further in accordance with a preferred embodiment of the present invention, there is provided a printhead assembly having a plurality of separately actuatable inkjet printing modules, and a relative movement between the printhead assembly and the substrate to be printed. and wherein relative movement between the printhead assembly and the substrate occurs in substantially only one direction.

Still further in accordance with a preferred embodiment of the invention, separately operable tubes each having at least one capillary tube and a device for pressurizing the ink in the at least one capillary tube to eject a droplet on the fly are provided. An inkjet printing device is provided that includes a printhead assembly that includes a plurality of inkjet printing modules and a device that provides relative movement between the printhead assembly and a substrate to be printed.

According to a preferred embodiment of the invention, the device for pressurizing the ink comprises a thermal device that evaporates the ink in the capillary tube and provides an immediate ejection of droplets. .

Also in accordance with a preferred embodiment of the invention, each of the separately operable inkjet printing modules includes first and second capillaries that are at least partially interdigitated.

Further in accordance with a preferred embodiment of the invention, each of the separately operable inkjet printing modules includes an ink evaporation volume located within at least one capillary tube.

According to another preferred embodiment of the invention, the device for pressurizing the ink comprises a piezoelectric device. The piezoelectric device is arranged to surround at least one capillary, preferably only one capillary.

According to a preferred embodiment of the invention, the separately operable inkjet printing modules are arranged in a staggered pattern.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood and appreciated from the following detailed description taken in conjunction with the drawings.

FIG. 1 depicts the structure of an inkjet printing element constructed and operative in accordance with a preferred embodiment of the present invention.
Reference is made below to FIGS. A through 1C. The inkjet printing element includes an outer capillary tube 10 preferably formed of fused silicon (fused silica) having an outer diameter of 363 microns and an inner diameter of about 150 microns. .

Disposed within one end of the capillary tube 10 is an inner capillary tube 12 preferably formed of molten silicone, the inner capillary tube having a
It has an outer diameter of 44 microns and an inner diameter of 30 microns.

Capillaries 10 and 12 are commercially available from Polymicro Corporation, Phoenix, Arizona, USA. The fit between the inner capillary tube 12 and the outer capillary tube 10 is such that the inner capillary tube can be easily inserted into the end of the outer capillary tube and that no ink leakage occurs between the inner and outer capillary tubes. It has become.

A conductive coating 16, 18, typically of rectangular cross-section, on its two surfaces insulated from each other.
A polygonal solid quartz glass fiber 14 having a polygonal shape is partially inserted into the end of the outer capillary tube 10 opposite to the end where the inner capillary tube 12 is located.

According to a preferred embodiment of the invention, the fiber 1
4 and the inside of the outer capillary tube 10 is such that at least one passageway 20 is defined between the fiber and the inner wall of the capillary tube 10, as shown in FIG. 1C. ing.

According to a preferred embodiment of the invention, fiber 1
4 is formed with a substantially flat end, and this end is
It is opposite and spaced from the correspondingly opposite end 24 of the inner capillary tube 12 . Preferably, a resistor 22 is formed in the flat end to electrically connect the conductive coatings 16 and 18. The volume between the resistor 22 and the corresponding end 24 of the inner capillary tube 12 is a firing chamber 26 that receives a supply of ink via one or more passageways 20.
is defined.

Electrical energy can be supplied to resistor 22 through conductive coatings 16 and 18 and corresponding conductors 28 and 30 connected to these coatings, thereby causing rapid discharge of resistor 22. Heating and corresponding evaporation of the ink within the generation chamber 26 occurs, and a bubble of ink vapor is formed within the generation chamber 26. The resulting fluid expansion within the generation chamber 26 causes the ink within the inner capillary tube 12 to be ejected as droplets through the end opening 32 defining the nozzle opening. By impacting the droplet with a substrate such as paper, a desired mark is formed on the substrate.

The fibers 14 and coatings 16, 18 also act as thermal conductors to transfer heat out of the generation chamber 26, thereby minimizing the time required to dissipate ink vapor bubbles. It will be appreciated that, at the same time, the duty cycle of the inkjet printing element is maximized.

Reference is now made to FIG. 2, which shows a plurality of printing elements 40 of the type shown in FIGS. 1A-1C mounted on a print head 42. As shown in FIG.

Print head 42 typically includes a nozzle plate 46 that engages end 47 (FIG. 1B) of capillary tube 10 adjacent opening 32, side plates 48, end plate 49, and a bottom plate. 50 and a housing 44 having a
It is equipped with An intermediate plate 52 is arranged above and generally parallel to plate 50.

Each printing element is sealingly mounted in a suitably sized hole formed in the plate 52 adjacent the end of the capillary tube 10 opposite the end opening 32. The protruding ends of the fibers 14 pass sealingly through suitably sized holes formed in the plate 50, below which the conductive wires 28, 30 are connected to the corresponding conducting conductors formed in the fibers 14. 16 and 18.

The volume between plates 50 and 52 preferably defines a reservoir 54, which reservoir preferably has a relatively large volume, for example 200 cc. As shown in FIG. 1A, the bottom edge 56 of the capillary tube 10
extends somewhat below plate 52 toward plate 50 so that a second ink supply conduit 58 is defined between edge 56 and plate 50 . Ink is drawn from the ink reservoir 54 into the generation chamber 26 through the passageway 20 and the conduit 58 by capillary action.

It is a special feature of the present invention that the ink reservoir 54 preferably holds enough ink to print several thousand pages, in contrast to the more limited ink reservoirs known in the prior art. . This improved ink retention capability is made possible by the fact that print head 42 is stationary in operation of the preferred embodiment of the present invention.

Reference is now made to FIGS. 3A-3B, which illustrate the structure of an inkjet printing element constructed and operative in accordance with another preferred embodiment of the present invention. The inkjet printing element includes an outer capillary tube 110, preferably formed from fused silicon (fused silica), having an outer diameter of 363 microns and an inner diameter of slightly less than 150 microns. have.

Disposed partially inside the capillary tube 110 at one end is an inner capillary tube 112, preferably formed of molten silicon, having an outer diameter of 144 microns. and an inner diameter of 30 microns.

Capillaries 110 and 112 are manufactured by Polymicro Corporation, Phoenix, Arizona, USA.
) is commercially available from. The fit between the inner capillary tube 112 and the outer capillary tube 110 is such that the inner capillary tube can be easily inserted into the end of the outer capillary tube and that no ink leakage occurs between the inner and outer capillary tubes. It has become. The outlet end 132 of the inner capillary tube 112 is sealingly attached to the top surface 146 of the printhead housing 144, while the bottom end 133 of the outer capillary tube 110 is attached to the printhead intermediate surface 152. Attached in a sealed manner.

A circular, solid quartz glass fiber 114 with mutually insulating conductive coatings 116, 118 on its two surfaces is connected to the bottom plate 150 of the print head via a relatively thick capillary tube 115. The fibers are sealingly attached to the inner capillary tube 112.
the outer capillary tube 110 opposite the end where the
partially inserted into the end of the Fiber 114 is manufactured by Polymicro Corporation of Phoenix, Arizona, USA.
ion).

According to a preferred embodiment of the invention, fiber 1
A non-contact engagement is provided between fiber 114 and the inside of outer capillary tube 110 such that an annular passageway 120 is defined between fiber 114 and the inner wall of capillary tube 110.

According to a preferred embodiment of the invention, fiber 1
14 is formed with a generally flat end, which end corresponds to the corresponding opposite end 124 of the inner capillary tube 112.
and spaced apart from this end. The flat ends are provided with conductive coatings 116 and 11.
Preferably, a resistor 122 is formed in electrical connection with 8. The volume between the resistor 122 and the corresponding end 124 of the inner capillary tube 112 defines a firing chamber that receives a supply of ink via one or more passageways 120.
chamber) 126.

Conductive coatings 116 and 118
and the corresponding conductors 1 connected to these coatings.
Electrical energy is transferred to resistor 1 through 28 and 130.
22, thereby causing resistor 122
Rapid heating of the ink and corresponding evaporation of the ink within the generation chamber 126 occurs, and a bubble of ink vapor is formed within the generation chamber 126. The resulting expansion of the fluid within the generation chamber 126 causes the ink within the inner capillary tube 112 to drop into the end opening 132 defining the nozzle opening.
ejected through. By impacting the droplet with a substrate such as paper, a desired mark is formed on the substrate.

Fibers 114 and coatings 116, 11
8 also acts as a thermal conductor to transfer heat out of the generation chamber 126, thereby minimizing the time required to dissipate ink vapor bubbles and reducing the duty cycle of the inkjet printing element. It is understood that the goal is to make it as large as possible.

The overall structure of the stationary printhead can be substantially similar to that shown in FIG. Figure 3A
As shown in FIG.
A second ink supply conduit 158 is defined between edge 159 and plate 152 . The ink flows through the passage 12 due to capillary action.
0 and into the generation chamber 126 from the ink sump 154 through conduit 158 .

Reference is now made to FIGS. 4A-4B, which illustrate some of the printing elements useful in piezoelectrically demanding inkjet printing. Typically about 20mm long, 0.3mm outer diameter,
A microcapillary 200 having an inner diameter of 0.24 mm has an inlet 202 narrowed to an inner diameter of about 0.03 mm and a nozzle or outlet 204 narrowed to an inner diameter slightly smaller than the diameter of the inlet 202. We are prepared. Inlet 202 can be connected to an ink reservoir and outlet 204 can be directed onto a substrate such as paper for printing.

A generally cylindrical piezoelectric element 206, shown partially in solid lines and partially in dashed lines in FIG. 4B, can be provided around the center of the microcapillary 200. The piezoelectric element can be actuated to contract when electrically actuated, constricting the microcapillary 200 and ejecting a droplet of ink from the outlet 204. Suitable piezoelectric cylinders are readily realized using conventional techniques, and suitable microcapillaries are manufactured by Polymicrotechnol, Phoenix, Arizona, USA.
ogy).

In another example, piezoelectric element 206 can be replaced with an element that has a C-shaped cross-section and thus does not completely surround microcapillary 200, as shown in solid lines only in FIG. 4B. The C-shaped piezoelectric element is
It can be restrained to the microcapillary 200 by suitable bonding means. When an electrical pulse is applied to the piezoelectric element, the piezoelectric element contracts and then expands, producing a shock wave that acts on the ink inside the microcapillary 200 and expels the ink droplet from the outlet 204. erupt.

Reference is now made to FIGS. 5A-5C, which illustrate an ink jet printing machine having a stationary print head constructed and operative in accordance with a preferred embodiment of the present invention. Typically, an inkjet printing press includes a base 250 that includes a paper drive assembly 252, such as a roller.
is attached and the paper drive assembly is operative to move paper 253 to be printed past a stationary print head 254. A platen element 256 supports paper 253 in the proper orientation relative to print head 254.

The stationary print head 254 may be identical to the print head 42 of FIG.
57 is preferred. In this alternating arrangement, the printing elements are arranged along a plurality of mutually oblique rows, for example six rows. The degree of slanting is such that adjacent ink droplets produced by corresponding elements of adjacent rows appear to be continuous. If a solid line is to be printed, the first element of the first row will jet first, then the first elements of the second to sixth rows will jet in sequence. Next, the second elements of the first to sixth rows eject in sequence, and so on. By providing interleaved printing elements, the spacing between adjacent dots of the printed line, i.e. the printing resolution, can be reduced to a relatively large minimum spacing between adjacent printing elements due to the relatively large diameter of the capillary tube. It can be made much smaller than.

The printing elements can be interleaved in any suitable manner. For example, 2400 nozzles can be provided, which can print a line on A4 size paper at a resolution of 300 dots per inch. The 2400 nozzles can be made into six rows of 400 nozzles, with a distance between each row of one-sixth of the printed line. The center-to-center distance between the nozzles may be 423 micrometers or one-sixtieth of an inch to provide a desired resolution of 300 dots per inch. The degree of oblique or alternating arrangement between corresponding nozzles is 423
It can be a micrometer.

The interleaving arrangement described above is achieved by providing separate inkjet printing elements that do not need to be etched into a plane as in the prior art. the result,
3 per inch (2.54 cm) across the entire width of the page
A stationary print head with a line resolution of 0.00 dots or more can be easily realized. By using such a stationary printhead, significantly enhanced printing speeds equal to or greater than those currently achieved by commercially available laser printers can be achieved. .

As shown in FIGS. 5B and 5C, respectively,
The devices of Figures 5A-5C have an open arrangement and a closed arrangement. In the open arrangement of FIG. 5B, the platen element and print head are not in contact and engagement, so paper can pass freely past the print head. In the closed arrangement of FIG. 5C, the platen element maintains the paper in intimate contact with the printhead for accurate transfer of ink to the paper.

It will be understood by those skilled in the art that the invention is not limited to what has been particularly shown and described above. The scope of the invention is defined only by the claims.

[Brief explanation of drawings]

FIG. 1A is a cross-sectional view of an inkjet printing element constructed and operative in accordance with a preferred embodiment of the present invention. 1B is a schematic perspective view, partially in section, of an inkjet printing element constructed and operative in accordance with a preferred embodiment of the present invention. 1C is a cross-sectional view taken along line CC of 1B.

FIG. 2 is a schematic perspective view, partially cut away, of an inkjet printing device using the printing element of FIGS. 1A to 1C;

FIG. 3A is a cross-sectional view of an inkjet printing element constructed and operative in accordance with a preferred embodiment of the present invention. 3B is a schematic perspective view, partially in section, of an inkjet printing element constructed and operative in accordance with a preferred embodiment of the present invention; FIG.

FIG. 4A is a simplified cross-sectional view of an inkjet printing element constructed and operative in accordance with a preferred embodiment of the present invention and including a cylindrical piezoelectric element. 4B is a simplified perspective view of two alternative embodiments of the device of 4A.

FIG. 5A is a simplified perspective view of an inkjet printing press with a stationary printhead having alternating printing elements in accordance with a preferred embodiment of the present invention. 5B is the VA, B-V of 5A when the inkjet printing machine is opened.
It is a sectional view taken along lines A and B. 5C is VA of 5A, B-VA, B when the inkjet printing machine is closed.
FIG. 3 is a cross-sectional view taken along the line.

[Explanation of symbols]

10, 12 capillary tube
14 Quartz glass fiber

Claims (14)

[Claims] 1. An inkjet printing apparatus comprising: a stationary printhead assembly having a plurality of separately operable inkjet printing modules; and means for transporting a substrate for printing in spaced relation. 2. An inkjet printing apparatus comprising: a printhead assembly having a plurality of separately operable inkjet printing modules extending over the entire writing dimension of a page; an inkjet printing apparatus comprising: means for relative conveyance with respect to the assembly. 3. An inkjet printing apparatus comprising: a printhead assembly having a plurality of separately actuatable inkjet printing modules; and means for providing relative motion between the printhead assembly and a substrate to be printed. An inkjet printing apparatus comprising: an inkjet printing apparatus, wherein relative movement between the printhead assembly and the substrate occurs substantially only along one direction. 4. In an inkjet printing apparatus, a plurality of separately operable inkjet printing modules each having at least one capillary and means for pressurizing the ink in the at least one capillary to expel a droplet on the fly. An inkjet printing apparatus comprising: a printhead assembly comprising: a printhead assembly; and means for providing relative movement between the printhead assembly and a substrate to be printed. 5. A ready-to-read inkjet printing apparatus comprising: a printhead assembly having a plurality of independently and separately operable inkjet printing modules; and means for transporting a substrate for printing in spaced relation. 6. A ready-to-read inkjet printing apparatus comprising a housing defining an ink reservoir and a plurality of independently operable inkjet printing modules disposed in the housing in communication with the ink reservoir. A ready-to-read inkjet printing apparatus comprising a printhead assembly and means for transporting a substrate for printing relative to and in operatively spaced relationship with the printhead assembly. . 7. Apparatus according to claim 1, characterized in that the number of inkjet printing modules exceeds 100. 8. The ink jet printing apparatus of claim 4, wherein each of said means for pressurizing ink comprises thermal means for evaporating ink in said at least one capillary to eject droplets in an instantaneous manner. An inkjet printing device comprising: 9. The inkjet printing apparatus of claim 8, wherein each of the separately operable inkjet printing modules comprises first and second capillary tubes that are at least partially interdigitated. Inkjet printing equipment. 10. The inkjet printing device of claim 8 or 9, wherein each of the plurality of separately operable inkjet printing modules has an ink evaporation volume located in at least one capillary tube. Inkjet printing equipment. 11. The inkjet printing apparatus according to claim 4, 8, 9 or 10, wherein the means for pressurizing the ink comprises piezoelectric means. 12. An ink jet printing device according to claim 11, wherein said piezoelectric means at least partially surrounds at least one capillary tube. 13. An inkjet printing device according to claim 1, wherein the plurality of separately operable inkjet printing modules are arranged in a diagonal arrangement. 14. The inkjet printing apparatus of claim 13, wherein the plurality of inkjet printing modules are arranged in angled rows such that ink droplets provided by corresponding elements of adjacent rows are An inkjet printing device characterized by a continuous appearance.