DE60108640T2 - DROPLETING DEVICE WITH SOLVENT NOZZLE PLATE - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION

The The present invention relates to a droplet deposition apparatus and especially inkjet printheads. The present invention relates in particular, method of attaching the nozzle plate to the printhead body.

GENERAL STATE OF THE ART

in the Field of ink jet printing can be known Problems with uneven printing, white lines etc. occur, with the cause of such misprints often in the nozzles, through the ink droplets are thrown to the ink receiving medium, can be found. Possible causes of mentioned above Printing errors are clogging of the nozzles, e.g. by drying the ink in the nozzle or Imperfections in the ink, and damage to the nozzles, e.g. due to the presence of hard pigments in the ink.

at SOHO printers (Small Office / Home Office, i.e. printers for small Offices or Home offices) Fixed issues with removal and replacement of the entire printhead. Larger inkjet printers are with larger printheads, even page width printheads, fitted. A typical example of such a printhead is e.g. in US Pat. No. 5,855,713. In this patent application is a printhead with a body with a multitude of parallel channels, in a common Channel boundary plane or area ends, and one on the body disclosed the channel boundary plane attached nozzle plate. As a result of that the body and the nozzle plate are firmly interconnected in the case of printing problems due to a defective nozzle effect Eliminate the whole printhead or else it has to be on a very cumbersome Process of remodeling with removal of the nozzle plate and its replacement through a new nozzle plate resorted become. In the above-described printhead structures, the nozzle plate makes less than 20% of the cost price of the printhead, resulting in The user is almost forced to do so in case of a defect inexpensive Printhead component all the expensive printhead of the printer to eliminate.

In EP-A 0 703 082 discloses a printer in which a nozzle plate detachable by means of a clamp on the printhead body is appropriate.

In JP-A 55 121081 is a nozzle plate by means of a guide rail solvable on the printhead body appropriate.

In JP-A 63 064755 become nozzle plates each with a single nozzle disclosed, wherein the nozzle plates by means of projections and grooves detachable on the printhead body are attached.

It So there is still a need for an improved releasably secured Nozzle plate.

TASKS AND BRIEF SUMMARY OF THE PRESENT INVENTION

task It is the object of the present invention to provide a droplet deposition apparatus with an easily replaceable nozzle plate provide.

Is solved the above object by a droplet depositing device according to the invention claimed in claim 1. In the dependent claims become preferred embodiments of the present invention.

According to the present Invention is a nozzle plate detachable by means of an adhesive layer on the printhead body attached, wherein upon removal of the nozzle plate from the channel boundary surface an adhesion break occurs between the adhesive layer and the channel boundary surface and no cohesive failure occurs within the adhesive layer. One important advantage of the present invention is that the nozzle plate removed along with the adhesive layer by a shearing force from the printhead body becomes. On the printhead body no or only a negligible adhesive residue remains. at a defective nozzle plate leave this Simply remove it together with the adhesive layer and can subsequently a new nozzle plate on Printhead body are attached, whereby the printhead body is used again.

SUMMARY THE FIGURES

The The present invention will be described with reference to the following figures. without restricting it to it. Show it

1 an exploded view of a first embodiment of a releasably mounted nozzle plate according to the invention,

2 an exploded view of a second embodiment of a releasably mounted nozzle plate according to the invention,

3 an exploded view of a third embodiment of a releasably mounted nozzle plate according to the invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

We have now found that it is in a multi-channel droplet deposition device - in particular in an inkjet printhead - with a body with a variety of channels, which terminate in a common channel boundary area, and one on the body the channel boundary plane fixed nozzle plate with through holes is possible a nozzle plate solvable on the body too fastened without this nozzle plate moving during the printing operation, whereby the distance between nozzle plate and ink-receiving material constant and register setting between the nozzle plate and the channels is maintained. This is even with printhead structures to observe, in which the channel opening is larger than the nozzle opening and that is, the ink when thrown through the nozzles by piezoelectric forces will, pressure on the nozzle plate exercises.

In the following, four embodiments according to the invention with different mechanical configurations will first be described. In the first and second embodiments, the nozzle plate is 102 at one on the printhead body 103 fixed frame 101 appropriate. In the third embodiment, so-called "mini nozzle plates" are used, and in the fourth embodiment, there is no frame 101 for supporting the nozzle plate 102 used.

Subsequently, will described as a nozzle plate solvable in the present invention is attached, i. using an adhesive layer, wherein when removing the nozzle plate from the channel boundary surface an adhesion break occurs between the adhesive layer and the channel boundary surface.

In a first, as in 1 shown embodiment of the invention, the nozzle plate is attached to a frame. The frame and / or the nozzle plate are releasably attached to the body. The frame 101 has a thickness d and inside dimensions X and Y and is equipped with a nozzle plate 102 with nozzles 102 fitted. At the side of the area 104 where the ink feeding channels 104a ends - this page is called the "channel boundary surface" - is body 103 edited so that the channel boundary surface lowered edges 105 and the remainder of the surface rises by a thickness d 'over these edges, where d' is chosen such that d '≤ d. Preferably, d = d 'so that the nozzle plate attached to the frame remains in contact with the rest of the channel boundary surface. This remainder of the channel confinement surface has dimensions X 'and Y' chosen to be such that X '≤ X and Y' ≤ Y. Preferably, X 'and Y' are equal to the internal dimensions X and Y of the frame, whereby the frame perfectly overlies fits the rest of the channel boundary surface. In this embodiment, although register marks on the channel boundary surface may facilitate the registration of the nozzle plate, they are not necessarily indispensable because the frame fits over the raised portion of the channel confinement surface and the nozzles register with ink ports of the ink channels in the channel confinement surface.

In a second, as in 2 As shown in the embodiment of the present invention, the nozzle plate is fixed to a frame, and the frame and / or the nozzle plate are detachably attached to the body as in the first embodiment. In the second embodiment, however, the channel boundary surface 104 not worked and just flat. The nozzle plate 102 supporting frame 101 is with the nozzle plate 102 between the frame and the channel boundary surface on the flat channel boundary surface 104 appropriate. Subsequently, the frame becomes body 103 the droplet depositing device attached. In the latter case, the body is provided at the channel boundary surface with at least one registration mark, so that the nozzles in the nozzle plate can be easily brought into registry with the openings of the channels in the channel boundary surface.

at both the first and second embodiments of the present invention Invention, the nozzle plate supporting frames made of any material known to those skilled in the art be prepared, e.g. made of stainless steel or another Metal (e.g., copper, aluminum, nickel, etc.) or hard plastic (e.g., polyvinyl chloride, polyurethane, polycarbonate, etc.).

In a third embodiment of the present invention, the nozzle plate is a micro injection molded part. The technique of micro injection molding is well known and enables the production of molded parts with micrometer dimensions with excellent control of tolerances and reproducibility. Furthermore, thanks to this technique for producing the nozzle plate, virtually all polymers known to those skilled in the art can be used. For example, thermoplastics, fiber reinforced thermoplastics, thermosetting plastics, and elastomers can be used to make a nozzle plate for use in a multichannel droplet deposition apparatus of the present invention. Micro injection molding can be used to produce "mini nozzle plates" that can be combined to form a large nozzle plate. This system has the advantage that when the nozzle is defective, only the "mini nozzle plate" carrying the defective nozzle is too is set.

In 3 Such a device is shown schematically. This figure shows two "mini nozzle plates" 102 each with 4 nozzles 102 , These "mini nozzle plates" can be shaped to fit precisely into a frame 101 at the channel boundary surface 104 on the body 103 the droplet depositing device is attached, can be fitted. The "mini nozzle plates" may have a notch along their length and the frame may be feathered 101 When pressing the "mini nozzle plates" fit into the frame in the notch and hold the "mini nozzle plates" in the frame. For their easy removal, the "mini nozzle plates" can also be provided with a handle.

The Number of nozzles in a "mini nozzle plate" aligns sch the nozzle diameter and the nozzle division and the purpose of a problem-free handling of the "mini nozzle plates" desired dimension of the "mini nozzle plate". Exemplary with a to be built from "mini nozzle plates" nozzle plate with a diameter of 100 microns and a pitch of 100 μm it may be advantageous to produce by micro injection molding "mini nozzle plates", the about 25 nozzles in one Row, whereby each mini nozzle plate thus obtained has a length of about 0.5 cm.

The frame 101 in which the "mini nozzle plates" are arranged, and / or the nozzle plate 102 are detachable on the body 103 attached, as is the case in the first and second embodiment. frame 101 However, it can also be an integral part of the body 103 be. In this case, the channel boundary surface is preferably machined to obtain raised edges, which then form a frame into which the "mini nozzle plates" are fitted. With a frame that is detachably attached to the body, a "mini nozzle plate" can be replaced more easily than with a frame that is permanently installed in the body.

In a fourth embodiment of the present invention, no special frame is used to support the nozzle plate. The nozzle plate may be either a "normal" nozzle plate or a "mini nozzle plate". The nozzle plate, preferably made of a polymer film with through holes, is detachable on the body 103 attached.

In all the above-described embodiments, the nozzle plate is 102 preferably made of a chemically resistant ablatable material in film form such as polyester, polyetheretherketone or more preferably polyimide. Polyimide has the advantage that it has a relatively low coefficient of thermal expansion and can be produced in a particularly flat film form, which approximates an optically flat surface or mirror surface and is suitable for the discharge side of the nozzle. The nozzle plate may also be coated with a low energy surface layer as described in US-A-5 010 356. The nozzle plate may also be of silicon.

The nozzles 102 in the nozzle plate may be attached by any technique known to those skilled in the art. One possible technique for making nozzles with a diameter of about 300 μm is vigorous mechanical drilling. A manufacturing process well known to those skilled in the art for smaller nozzle orifice diameters (ie, less than 200 microns, preferably less than 100 microns) is laser burning. A preferred technique for making small diameter nozzles is plasma etching, in which nozzles with very smooth walls can be made. This wall smoothness helps prevent clogging of the nozzles and misalignment of the ink. A very good method of making the nozzles is the combination of laser burning and plasma etching, using a method whereby the laser beam properly focuses and positions through the nozzle plate material an opening of smaller diameter (than the diameter eventually needed in the nozzle). is bored. This first step of laser burning is followed by a plasma etching step in which the diameter of the laser burned opening is broadened to the final diameter of the nozzle.

in the The following is a description of the ways, such as a nozzle plate according to the present Invention solvable is attached.

in the In general, the nozzle plate by mechanical means such as screws, clamps, a kind of Snaps, Spiral springs etc. solvable on the body be attached. It can also be releasably secured by means of magnetic forces be, e.g. by using a magnetic material for production of the frame or by incorporating permanent magnets into the frame, in the body or in both.

In the present invention, a nozzle plate is releasably secured to the printhead body by means of an adhesive layer, and when the nozzle plate is removed from the channel boundary surface, the adhesion between the adhesive layer and the channel boundary surface is released and no cohesive failure occurs within the adhesive layer. In a substantially vertical stress of the bonded nozzle plate no movement or displacement of the nozzle plate is observed, however, upon application of a shear force, the nozzle plate together solved with the adhesive layer from the printhead body. This effect is achieved by a suitable combination of three materials, ie the adhesive and the materials of the two parts that are bonded together by the adhesive. If no intermediate layers are used, these two parts are the nozzle plate and the channel boundary surface. The following also discusses the use of interlayers.

The nozzle plate is preferably made of polyimide. Initially, certain other suitable materials have been mentioned. The channel boundary surface is preferably made of PZT, a piezoelectric ceramic material. Other possible materials for the channel confinement surface include ceramic materials other than PZT, stainless steel and Al ₂ O ₃ sintered alumina. The adhesive is preferably a so-called "removable" pressure sensitive adhesive, although certain hot melt adhesives are contemplated Examples of pressure sensitive adhesives that are more or less suitable depending on, inter alia, the materials used for the two parts to be bonded together by the adhesive Acronal 4D, Acronal 50D, Acronal DS 3454, Acronal 35D, Acronal LA 4495, all marketed by BASF, Adhesive 13D and Adhesive 51R, both marketed by CYG, France, Primal EP-6120 and Primal PS-61D, both sold by Rohm & Haas, SE4367, SE1390 and SE4397, all sold by HB Füller, UK, and R300, R361 and R397, all sold by Rhône-Poulenc.

Between the nozzle plate and the channel boundary surface can different types of interlayers are used.

A First type of interlayer is an adhesive layer that is used to improve the adhesion between the nozzle plate and the adhesive on the nozzle plate can be attached. First the adhesive layer is applied to the nozzle plate applied and then the adhesive layer is applied to the adhesive layer. Suitable adhesive layers can through experiments for a given type of nozzle plate and adhesive has been determined.

A second type of adhesive layer is a release force enhancing layer, to reduce the adhesion between the channel boundary surface and the adhesive can be applied to the channel boundary surface. When choosing appropriate the release force enhancing products directed depending on the type of channel boundary surface and the adhesive. exemplary are products such as Polywax 1000 (polyethylene wax) from Bareco Div., Vydax 1000 [(polytetrafluoroethylene (PTFE)] from DuPont and Plexigum M345 (polymethyl methacrylate) by Rohm & Haas.

A third type of interlayer is an intermediate structure, like a between the channel boundary surface and the nozzle plate arranged molybdenum plate with nozzles. In this case, the nozzle plate becomes preferably releasably with an adhesive as described above attached to the intermediate structure. The intermediate structure, however, can also detachable attached to the channel boundary surface become. In both cases is between the nozzle plate and the channel boundary surface an adhesive layer is applied, either between the nozzle plate and the intermediate structure, between the intermediate structure and the Channel boundary surface or between both nozzle plate and intermediate structure as between intermediate structure and channel boundary surface, wherein in the latter case two adhesive layers are used.

The Adhesive layer is preferably used e.g. by coating on the nozzle plate (or already on the nozzle plate applied (n) intermediate layer (s)) and not attached to the channel boundary surface. The provided with the adhesive layer nozzle plate is then on the channel boundary surface glued.

The nozzle plate may have waves as described in US-A 5,855,713. In this Case are micro cavities and adhesive surface shaped in the form of waves. The waves are usually 2 to 4 μm deep and have a spacing or wavelength of 10 to 20 μm on. The between the micro cavities webs present preferably have a width in contact with the channel boundary surface of between 0.05 times and 0.25 times the width of the microvoids. By controlling the composition of the adhesive and the relative Dimensions of the webs between the cavities may be the bond strength the nozzle plate so be set that a strong adhesion is obtained when the nozzle plates is stressed vertically (this force mainly due to the ink pressure in the to the nozzle plate leading Channels), and one enough weak adhesion is obtained when separating the nozzle plate from the body one Shear force is applied.

All Types of intermediate layers as well as waves can be both mutually as also with the above-described embodiments with different mechanical configurations are combined.

EXAMPLE 1

• Nozzle plate: Kapton film (Kapton is a trademark of DuPont / Kapton is a polyimide), Type 200 HN, nominal thickness: 50.8 μm,
• - Channel boundary surface: PZT,
• - Adhesive: Acronal 50D (from BASF), ratio = 50% (this adhesive is an aqueous acrylate-based latex).

The adhesive is applied to the Kapton ^™ film by means of a 20 μm doctor blade. After drying, the thickness of the adhesive layer is about 10 microns. The adhesive coated Kapton film is applied under pressure to the channel boundary surface (using a Codor Lamipacker LPP650 / the laminating rollers are set to a pressure of 1 mm to obtain sufficient pressure between the two rollers).

48 Hours after bonding the nozzle plate is released from the channel boundary surface. Of the Adhesive is completely removed together with the nozzle plate the channel boundary surface away. No adhesive residue remains on the channel boundary surface back.

EXAMPLES 2 to 4

• – Beispiel 2: Acronal 35D (von BASF), Verhältnis = 50%,
• – Beispiel 3: Robond PS-8120 (von Rohm & Haas), Verhältnis = 54–55%,
• – Beispiel 4: Robond PS-8111 (von Rohm & Haas), Verhältnis = 56–57%.

The following adhesives are used

• Example 2: Acronal 35D (from BASF), ratio = 50%,
• Example 3: Robond PS-8120 (from Rohm & Haas), ratio = 54-55%,
• Example 4: Robond PS-8111 (from Rohm & Haas), ratio = 56-57%.

Otherwise are the exams same as in Example 1 tests. They will be the same test results as obtained in Example 1.

EXAMPLES 5 to 8

The PZT is replaced by aluminum oxide Al ₂ O ₃ . Otherwise, the tests are the same as in Examples 1 to 4. The same test results as in Example 1 are obtained.

at Piezo inkjet printers using ink channels - with walls that piezo print on the ink in the channels exercise can - in one common channel boundary surface ends, the use of an inventively releasably attached to the channel boundary surface nozzle plate very advantageous. However, this does not mean that inkjet printheads, in which the ejection of the Ink e.g. by sound waves, bubble generation, thermal expansion etc., would not be beneficial over the above described simply replaceable nozzle plates to dispose of. With any inkjet printhead, it's a desirable feature only the nozzle plate and not having to replace the entire printhead, especially inkjet printers, where the printhead - regardless of the way in which the ink is ejected - a wide matrix, even a page-wide matrix of nozzles includes. The present invention can be applied not only to piezo inkjet printheads, but be applied to all types of droplet deposition devices.

To the detailed description of preferred embodiments of the present invention It should be clear to the experts in this field that here within the scope of the invention the following claims numerous Modifications possible are.

101

frame

101

feathers

102

nozzle plate or "mini nozzle plate"

102

jet

103

body

104

Channel boundary surface

104a

channels

105

lowered margins

Claims (10)

A multi-channel droplet deposition device having a body ( 103 ) with a plurality of channels ( 104a ) located in a common channel boundary area ( 104 ) and a detachable at the channel boundary surface ( 104 ) attached nozzle plate ( 102 ), wherein the nozzle plate ( 102 ) Nozzles ( 102 ), which are selected from the plurality of channels ( 104a ) projecting liquid drops, characterized in that the nozzle plate ( 102 ) by means of an adhesive layer detachably on the channel boundary surface ( 104 ) and the adhesive layer is assembled such that, when the nozzle plate is removed from the channel boundary surface, an adhesion break occurs between the adhesive layer and the channel boundary surface (FIG. 104 ) occurs without cohesive failure within the adhesive layer. Multi-channel droplet separation device according to claim 1, characterized in that the nozzle plate ( 102 ) Has through holes and on the channel boundary surface ( 104 ) of the body ( 103 ), wherein droplet ejection nozzles ( 102 ) be formed. A multi-channel droplet deposition apparatus according to any one of the preceding claims, further comprising a first intermediate layer between the adhesive layer and the nozzle plate (10). 102 ) contains. A multi-channel droplet deposition apparatus according to any one of the preceding claims, further a second intermediate layer between the adhesive layer and the channel boundary surface (FIG. 104 ) contains. Multi-channel droplet separation device according to one of the preceding claims, characterized in that the nozzle plate ( 102 ) is formed of a polymeric film material and on a nozzle plate ( 102 ) supporting frame ( 101 ) is attached. Multi-channel droplet depositing device according to one of the preceding claims, characterized in that the body ( 103 ) further includes register marks by means of which the nozzle plate ( 102 ) in registers with the plurality of channels ( 104a ) is placed on the channel boundary surface. Multi-channel droplet separation device according to one of the preceding claims, characterized in that the nozzle plate ( 102 ) a plurality of mini nozzle plates ( 102 ) contains. Multichannel droplet deposition apparatus according to the preceding claim, characterized in that the plurality of mini-nozzle plates ( 102 ) detachable in a frame ( 101 ) is arranged. Multichannel droplet deposition device according to one of the preceding claims, characterized in that the multi-channel droplet deposition device a printhead structure for use in ink jet printing. Multi-channel droplet deposition device according to any one of the preceding claims, characterized in that the plurality of channels ( 104a ) Comprises means for piezo-printing ink at the channel boundary surface ( 104 ).