The device applying drops

 

(57) Abstract:

Forming droplets of the piezoelectric printhead has a wall of a channel formed of a piezoelectric material with electrodes on their length. In parts of the channels, which are open to the supply channel of the ink, the piezoelectric material is locally blocked, for example, by reducing the width of the electrode or the introduction of a material with a lower dielectric constant between the electrode and the piezoelectric material. The result is a lower capacitive load. 8 c. and 23 C.p. f-crystals, 10 ill.

The present invention relates to a device applying the drops, in particular, strainoptic heads having a lower plate including a piezoelectric material and formed with multiple parallel channels with open tops spaced apart in a direction normal to the length of the channels, each channel formed at least partially facing each other, side walls and bottom surface, passing between the side walls, and at least the side walls contain a piezoelectric material. The present invention also includes a method is tov EP-A-0277703, EP-A-0278590 and EP-A-0364136, and they use a piezoelectric material is driven to shift the mode to change the volume of the chamber for ink and, consequently, the issuance of ink drops. In the patent EP-A-0341929 described a method of controlling such actuators and explained that each drive has a capacitive load. As you can understand, this capacitive load current consumption and the energy, which adversely affect both the size and cost of the circuit part of the drive. In addition, it was found that the current in the circuits and the electrodes of the printhead, may also lead to the formation of heat, which, in turn, will affect the viscosity of ink: as is the case in many types of inkjet devices, changing the viscosity of the ink changes the speed of release of droplets of ink, which, in turn, manifests itself in the form of the error location drops in the printed image.

To reduce the capacitive load of the printhead, it was proposed to limit the use of piezoelectric material in the printhead to those areas where it is actually required piezoelectric effect, that is, in the walls of the channels are active (closed) areas to the ment head. In practice this can be achieved through the inclusion of inserts made of a piezoelectric material in the substrate with a lower dielectric constant, forming channels that pass through the insert and through the base and through the application of electrodes along the length of each channel. Only the portion of the wall of each channel, which contains a piezoelectric material is deformed (bent) by the action of the electric field applied to the electrodes, while the remainder of each wall and any associated joint area is only low capacitive load. However, inclusion of the piezoelectric insert is a complex process and, therefore, makes this method expensive.

The known method (see U.S. patent N 3245895) coating the surface of the item, including the location of the element in the chamber and exposed to a beam of vapor of the substance. However, this method also suffers from the aforementioned disadvantages of the prior art.

The purpose of this invention is the provision of printheads that have a lower capacitive loads than known designs, however, are not difficult to manufacture, and is it the invention according to the first aspect of the invention is a device applying the drops, containing lower plate including a piezoelectric material and having a multitude of parallel channels with open tops, placed at a distance from each other in the direction perpendicular to the length of the channels, each channel formed at least partially facing each other, side walls and bottom surface, passing between the side walls, and at least the side walls contain a piezoelectric material and electrodes for application of an electric field to the piezoelectric material for the transverse displacement of the side wall, top plate, facing the bottom surfaces of the channels and attached to the side walls for closing the channels in their upper parts, and the channels configured to supply the fluid medium drops and communicated with a nozzle for releasing from it drops, and each channel has one part that is open on the side lying parallel to the axis of the channel for communication with means for supplying fluid drops, and another part that is closed on all sides and lying parallel to the axis of the channel, in which, according to the invention, the respective side walls including a piezoelectric material in one part of each Kana is hidden, that lateral displacement of the walls in the "open" sections of the canal is not only undesirable, but because of the blocking walls in such "open" sites it is possible to achieve a reduction of the capacitive load in HP printheads manufactured essentially in accordance with the conventional method of forming channels in the base, containing a homogeneous layer of piezoelectric material. Consequently, it is possible to eliminate the above complex manufacturing methods.

Preferably, in one part of each channel layer of material having a dielectric constant lower than that of the piezoelectric material was placed between the piezoelectric material and at least one of the electrodes placed on opposite sides of walls to block the piezoelectric material.

It is advisable that the electrodes are placed in one part of each channel, passed on the shorter height of the respective side walls than the electrodes placed in the other part of each channel, for inefficient excitation of the piezoelectric material in one part, with the blocking of this part.

In accordance with the second aspect, the invention Zack is Ala, polarized in a direction perpendicular relative to a layer that contains a multitude of parallel channels with open tops, placed at a distance from each other in the direction perpendicular to the length of the channels, each channel formed at least partially facing each other, side walls and bottom surface, passing between the side walls, with at least the side walls contain a piezoelectric material, an upper plate facing the lower surfaces of the channels and attached to the side walls for closing the channels in their upper parts, moreover, the channels configured to supply a liquid fluid medium droplets and communicated with a nozzle for the outlet drops, each channel has one part that is open on the side lying parallel to the axis of the channel for communication with means for supplying fluid drops, and another part that is closed on all sides and lying parallel to the axis of the channel, the electrodes placed on opposite sides of the side walls, to form actuators shear mode displacement drops of channels connected to the actuators, and each electrode takes place essentially along the entire length of the channel, in which, centrado, placed on opposite sides of the side walls, placed a layer of material having a dielectric constant lower than that of the piezoelectric material.

This device achieved a lower capacity than in conventional devices without the complexity associated with "built-in" piezoelectric inserts, as described above. In one part of the channel, which is open for the ink supply, the walls should not be shifting. Therefore, the electrodes in such part can be separated from the piezoelectric material of the channel walls with a layer of material having a lower dielectric constant than the piezoelectric material, thereby blocking this part of the piezoelectric material. The resulting capacitive load between the electrodes on opposite sides of the wall of the channel in this one part is lower than those obtained in the case of a single piezoelectric material (as happens in other "closed" part of the channel) and therefore contributes to reducing the total capacitive load of the printhead.

In accordance with a specific embodiment of the invention, each of the one and the other parts are formed, at least partially, sootvetstvujushij side walls of one and the other parts are essentially the same.

Such a variant embodiment of the invention is particularly suitable for manufacture in this case, where there is no change in the depth of machining of the channel required, at least in front of the TV. In this embodiment of the invention, the other part of the channel can be carried out at a constant depth of the nozzle. Regardless of this, one and the other parts may be in contact.

Preferably, for each channel, the nozzle was located near another part of the channel.

It is advisable that for each channel one and the other side was touching.

Preferably, in another part of the electrodes were placed on the surface of the piezoelectric material of the respective channel walls.

Preferably, the electrodes are placed on opposite sides of the side walls, at least one part of each channel were located at the top of each side wall of the channel remote from the bottom surface.

This arrangement is particularly suitable for application using a known method, "metallization angle". In particular, the electrode may preferably be approximately at what goes on at 10% or less of the height of the corresponding wall of the channel.

It is desirable, also, to each of the channels contained an additional part with the wall of the channel of less height than the walls of one channel or the other parts, and the electrodes were placed to face each other, the channel walls and the Foundation of each of the channels, and between the electrodes facing each other with the walls and base of each channel, was placed a layer of material having a dielectric constant lower than that of the piezoelectric material.

The electrodes in additional parts serve as connection points between the electrodes in the channels and the external circuits of the exciting device. The layer of material with a low dielectric constant between the electrodes and the walls of the channel reduced height reduces capacitive loading these areas.

According to a third aspect of the invention a method of manufacture of the device causing droplets containing

(a) the formation of multiple parallel channels in the bottom plate containing a layer of piezoelectric material,

(b) applying a layer of material, at least one of the facing to each other of the side walls of the first part of each channel, and the material is on the second part of each of the channels free from this material,

(c) deposition of electrode material on the facing each other, the side walls of the first and second parts of the channels. Preferably, the method included:

(d) masking the second portion of each of the channels before applying a layer of material on at least one of the facing to each other of the side walls of the first part of each of the channels,

(e) demaskirovanie the second part before applying the electrode material on the facing each other, the side walls of the first and second parts of the channels.

Preferably, the electrode material was applied by metal vapor beam aimed at the wall at an angle to the facing to each other surfaces of the channel.

According to a fourth aspect of the invention, an apparatus applying droplets containing the lower plate having a layer of piezoelectric material polarized in the direction perpendicular to the layer containing many parallel channels with open tops, placed at a distance from each other in the direction normal to the length of the channels, each channel formed at least partially facing each other, side walls having coplanar upper surface the piezoelectric material, the top plate facing the bottom surfaces of the channels and attached to the side walls for closing the channels in their upper parts, and the channels configured to supply a liquid fluid medium drops and communicated with a nozzle for releasing from it drops, each channel has one part that is open on the side lying parallel to the axis of the channel for communication with means for supplying fluid drops, and another part that is closed on all sides lying parallel to the axis of the channel electrodes, placed on opposite sides of the side walls for education thereby drives the shear mode displacement drops of channels connected to the actuators, and each electrode takes place essentially along the entire length of the channel, in which, according to the invention, the electrodes are placed in one part of each channel, are on the shorter height of the respective side walls than the electrodes placed in the other part of each channel.

In such a device again easiest way is achieved a lower capacity than in conventional devices. In one part of the channel, which is open to the ink supply means, the walls should not be offset and, therefore, the electrodes in such a sneeze voltages to the electrodes in a closed part of the channel, but insufficient to actuate the piezoelectric material in the open part, which, thus, is locally blocked. In the closed part of the electrodes are, respectively, a larger segment down the wall, sufficient to cause movement of the channel walls. Thus, the capacitive load of the channel walls in one (open) part, at least, reduced with respect to conventional devices, which reduces the capacity of the printhead as a whole.

Preferably, each of the one and the other parts have been formed, at least partially, side walls essentially constant height, and the height of the respective side walls of one and the other part was essentially the same.

Such a variant embodiment of the invention is particularly suitable for manufacturing, since in this case no change of the depth of machining of the channel required, at least in front of the TV. In this embodiment of the invention is another part of the channel can be carried out at a constant depth up to the nozzle. Regardless of this, one and the other parts may be in contact.

Preferably, for each of the one and the other side was touching.

Preferably, the electrodes are placed on opposite sides of the side walls, at least one part of each channel were located in the upper part of each side wall of the channel remote from the bottom surface.

Such a device is particularly suitable for application using a known method, "metallization angle".

Preferably, the electrode is preferably held 10% or less of the height of the corresponding walls of the channel in one part.

Preferably, the electrode was placed in the other part, and were approximately half the depth or substantially the entire depth of the corresponding wall of the channel.

Most preferably, the ratio of the segments of one and the other parts of the channel was approximately 2 or more.

The present invention according to its fifth aspect is a method of manufacturing a device applying droplets containing

(a) forming in the bottom plate containing a layer of piezoelectric material, a multitude of parallel channels separated by walls of channels having coplanar top,

(b) deposition of electrode material on obrashennih walls,

(c) deposition of electrode material on the facing each other, the side walls of the second part of each of the channels in the second period of the height of the respective side walls, and first and second segments are different in length.

In this case, in this invention using known in themselves ways of application, allows you to make low capacitance printhead without difficulty.

Preferably, the method contains:

(d) masking the second portion of each of the channels before applying a layer of electrode material on the facing to each other of the first wall part of each of the channels in the first segment of the height of the respective side walls,

(e) demaskirovanie the second part before applying the electrode material on the facing each other, the side walls of the first and second portions of each of the channels.

This process is simple to implement and does not require disturbing the vacuum between the stages of application.

Preferably, the first segment was longer than the second length and the second length is preferably not more than 10% of the height of the wall.

This can be achieved by the fact that the electrode material is applied using a beam vapor may in the first part should be more steep, than the angle for applying the second part.

According to the sixth aspect of the invention, an apparatus for the deposition of droplets having a bottom plate containing a layer of piezoelectric material polarized in the direction perpendicular to the layer having a multitude of parallel channels with open tops, placed at a distance from each other in the direction perpendicular with respect to the length of the channels, each channel formed at least partially facing each other, side walls having a height and a bottom surface, passing between the side walls, with at least the side walls contain a piezoelectric material, an upper plate, facing the bottom surfaces of the channels and attached to the side walls for closing the channels in their upper parts, and the channels configured to supply the fluid medium droplets and communicated with a nozzle for the outlet of the droplets, and each channel has a part enclosed on all sides and lying parallel to the axis of the channel, the electrodes placed at least on opposite sides of the side walls for education thereby drives the shear mode displacement drops from the according to the invention, between the piezoelectric material and at least one of the electrodes in the regions other than the closed part of each channel is placed a layer of material having a dielectric constant lower than that of the piezoelectric material.

According to the seventh aspect of the invention, an apparatus for the deposition of droplets having a lower plate including a piezoelectric material and having a multitude of parallel channels with open tops, placed at a distance from each other in the direction perpendicular to the length of the channels, each channel formed at least partially facing each other, side walls having a height and a bottom surface, passing between the side walls, with at least the side walls contain a piezoelectric material, an upper plate, facing the bottom surfaces of the channels and attached to the side walls for closing the channels in their upper parts, and the channels configured to supply a liquid fluid medium drops and communicated with a nozzle for the outlet drops, and each channel has a part enclosed on all sides lying parallel to the axis of the channel, the electrodes for the application elektricheskij from the closed part of each channel, between the piezoelectric material in the side walls and at least one of the electrodes is placed a layer of material having a dielectric constant lower than that of the piezoelectric material.

According to the eighth aspect of the invention, a method for coating the surface of the element with channels, each of which has two facing each other, the side walls and the surface between them, in which the coating is applied on the side walls by placing the element in a vacuum chamber, impacts on the side walls of the element beam metal vapor, and by switching between the state in which the chamber is under vacuum, and the state in which the side walls of the element is bombarded with ions, or free radicals, and in the condition in which the chamber is under vacuum, the metal vapor beam is directed under a non-zero angle to the walls of the channel.

Preferably, ions or free radicals represented oxygen or nitrogen.

It is desirable that the beam metal vapor contained evaporated aluminum.

Now the invention will be described by example with reference to the drawings, in which:

Fig. 1 is a view in isometric/P> Fig. 2 is a view in cross section of the printhead of Fig. 1 along the line a-a of Fig. 1.

Fig. 3 (a), (b) and (c) are views in transverse section of part of a printhead according to Fig. 1 along lines B-B, C-C and D-D, respectively.

Fig. 4 is a view in transverse section corresponding to the view of Fig. 2 and including the first aspect of the invention.

Fig. 5 (a), (b) and (c) are views in transverse section taken along the lines B'-B', C'-C' and D'-D' of Fig. 4 and the corresponding cross-sections in Fig. 3 (a) - (C).

Fig. 6 is a view in transverse section corresponding to the view of Fig. 2 and including a second aspect of the invention.

Fig. 7 (a), (b) and (c) are views in transverse section on the line B '-B', C', C" and D-D ' of Fig. 6 and the corresponding cross-sections in Fig. 3 (a) - (c).

Fig. 8 is a schematic illustration of a section through the corresponding second aspect of the invention the wall of the channel.

Fig. 9 is a view in section corresponding to Fig. 6, and illustrates the step that corresponds to a second aspect of the invention method.

Fig. 10 is a view in section along the longitudinal axis of the channel of the other printhead according to the present invention.

In Fig. 1-3 illustrates, in isometric and section views, respectively, of a typical inkjet printhead 8, SA-5016028. It comprises a base 10 of a piezoelectric material mounted on the circuit Board 12, which shows only the area containing the connecting track 14.

The base 10 is formed of multiple parallel grooves, passing into the layer of piezoelectric material, as described, for example, in U.S. patent US-A-5016028. Each groove contains the front part, which is relatively deep to provide ink channels 20, separated by opposite walls 22 of the actuator, with evenly-coplanar top surface, and a rear part, which is relatively small and is intended for formation locations 23 to the connecting tracks. The front and rear parts are connected by plot R "output" channel, the radius of curvature of which is determined by the radius of the cutting tool used for the formation of channels (and are described, for example, in the aforementioned patent EP-A-0364136).

As shown in Fig. 3, after the formation of the grooves in them is applied to a metallic surface to create in front of the electrodes 26 on the opposite front sides of the channels 20 for the ink, where the electrodes are approximately half the height of the channel from the upper parts of the m in each channel 20 (Fig. 3 (c)). The upper part of the walls remain without metallization to the track 24 and electrodes 26 formed isolated driven electrodes for each channel. This method of metallization in the technique is known, for example, of the aforementioned patent EP-A-0364136.

After application and, optionally, coating the base layer 10 pestiviruses substances for electrical insulation of parts of the electrode ink, the base 10 is installed, as shown in Fig. 1, the circuit Board 12, and made associated wire connections 28, connecting the connecting track 24 on the base part 10 to the connecting tracks 14 on the circuit Board 12.

Cover 16 is attached by attachment to the upper parts of the walls 22 of the actuator, thus forming many "closed" channels 20. At one end of each channel has access to the supply replenished ink: in the example shown, this occurs through a window 27 in the cover 16. At the other end of each channel is placed a nozzle 30, which may be formed, preferably, by removing excimer laser ultraviolet range) in the plate 17 of the nozzle connected to the printhead.

In this example, the print head is driven by rnil to the nozzles 30. As is known, for example, from the patent EP-A-0277703, the corresponding flow waveform voltage to the electrodes on either side of the wall of the channel leads to a potential difference, on the wall, which, in turn, causes the deformation of polarized piezoelectric material of the channel walls in shear mode and wall for deflection in the transverse direction relative to the corresponding channel. Thus, it can deflect one or both of the walls bounding the channel for ink.

The displacement of the walls in the channel reduces the amount of channel and sets the pressure in the ink along the stretch of canal, closed top and bottom of the base and cover, respectively, and closed on both lateral sides of the respective channel walls. This period is known as the "active" part of the channel and is indicated in Fig. 1 and 2 the reference position "L". The distribution of pressure causes the ejection of ink droplets from the nozzle.

As mentioned above, the print heads described species represent capacitive load: in the front part (corresponding to Fig. 3 (a) and (b) a capacitor formed by the wall of the channel and electrodes placed on both sides and in the rear part of the channel, it should be clear that not only is Okami 24, contribute to the capacitive effect.

Fig. 4 is corresponding to Fig. 2 is a view in section, and illustrates the corresponding first aspect of the present invention the printhead. Fig. 5 depicts the corresponding cross sections. You may notice that the design of the "active" segment of the printhead of Fig. 4 remains the same as the conventional design of the head, with the electrode 26' passing down approximately half the height of the wall.

However, in the part of the channel with full depth denoted by the reference position "N", which is open on one side to the window 27 of the ink and, therefore, is not part of the "active" section of the channel, the electrode 26 passes only along the upper part of the wall. This is sufficient for transfer of excitatory signals from the connection tracks 24 to the electrode 26' of the active part of the channel, and yet, as is evident from Fig. 5 (b), significantly reduces the capacitive loading of this part of the channel by reducing the area of the piezoelectric material placed between the electrodes of the channel (this follows from the established principle that the capacitance of the capacitor with plate plates with area A, separated materialistically permeability of free space).

The electrode 26 has been reduced depth is also preferably used for the "final" site R, where it connects with the connection tracks 24 which are formed in the usual way.

As for the production of the above tracks 26', 26" are different heights, it is preferably, but not exclusively - is achieved by vapor deposition of metal. The principles of this method are fully described in the patent EP-A-0364136 and therefore there will not be considered. A piezoelectric body formed therein channels were initially exposed to the metal vapor beam directed perpendicular to the plane of the body, i.e. essentially parallel to the side walls of the channel, everywhere except the back of the "C" shielded grooves. As shown by the dotted lines 60 in Fig. 5 (c), because it is applied to the metal, forming a connecting track 24 of a thickness sufficient to withstand the process of connecting wires, usually 2-4 microns.

Then screening those parts of the channels, which serve for the formation of the active segment L printhead, remove, and body with formed channels and the metal vapor beam rotate relative to each other in the position shown in Fig. 5 (a), so e is offered by the depth metallization 125 μm) and thickness, usually equivalent to the application of 1 μm on the surface located normal to the beam metal vapor. It should be clear that the relative rotation must be performed twice to ensure that the coating on both side walls of each channel. This part of the process is opened in the patent EP-A-0364136 the method of applying electrodes.

Finally, shielding the remaining parts of the channel, namely, N and R, are removed, and the body formed by the channels and the metal vapor beam rotate relative to each other again until the smaller the angle shown in Fig. 5 (b), thereby causing the smaller electrode 26" (a typical depth of 25 mm) in parts of R, N, as well as along the upper part of the electrode 26' caused in the active region at the previous stage. In the active area of the channel, small electrode contributes to the conductivity along the stretch of the active region, it is especially advantageous where there is used an electrode material having a high specific resistance. Again requires an additional rotation to allow deposition of metal along the upper part of the other walls.

The above-described method has the associated advantage that the tick of the electrodes in a particular covered by the metal region. Thus, the first stage of deposition can be performed with higher speed application that was deposited in the shortest period of time, the metal layer quality, sufficient only for the formation of connective paths that remain attached to the ceramic substrate during the process of connecting wires. On the other hand, the second stage of application of the electrodes in the active segment of the channel can be performed with a lower rate of application, to ensure the electrical continuity of the electrodes deposited on the walls in the active part of the channel. The last stage, on which are applied the small electrodes 26", again you can run with a higher speed application, which reflects the fact that the electrode is applied at an angle close to the perpendicular.

Screening can be performed by a physical mask that is placed between the base 10 and formed channels and a source of metal vapor, preferably near the element 10 formed by the channels to get a good sharpness of the edges of the metallization. Perfect mask is made from a material such as polyimide or metal, which is suitable for use in the vacuum system. In each m the figures above, you can delete or by extrusion, or removal of the sliding way from the bottom with educated channels, or hanging them so that each of them was opened by one, after an appropriate stage of the application. Each mask is preferably removed without opening the vacuum chamber, which otherwise can lead to the formation of oxide layers between the sequentially formed layers of the electrode.

An alternative method of applying electrodes includes the initial application of a small electrode along the entire length of the channel. Then in the camera, enter the mask for shielding the inactive part of the "N" channel before applying the usual way, is known from the patent EP-A-0364136, electrode half the depth of the wall in the active part of the "L" channel and connecting tracks in the small rear "C" channel.

Unwanted deposition of metal on the top of the walls can be avoided by thermoplastic "removal" of the film, as it is known, for example, from the patent EP-A-0397441, or overlay isolation after application, as in the patent EP-A-0364136. Additional precipitation in areas such connecting paths during subsequent deposition of, for example, electrodes 26' or 26", favourably taken into account when willingale you want to put only 2 microns of the material of electrode: electrode material, struck in the rear in subsequent phases of application, leads to a final desired thickness of the connecting tracks 3-4 μm).

Fig. 4 and 5 illustrate the above aspect of the present invention when applied to a printhead, having a wall of a piezoelectric material polarized perpendicular to the layer of piezoelectric material and in the same direction, type so-called "cantilever design" as disclosed in patent EP-A-0354136. However, the present invention is by no means the case is not limited to such constructions, it is equally well can be applied to a printing head having a "herringbone" structure with a piezoelectric material polarized in two opposite directions, as is known, for example, from the patent EP-A-0277703. This latest design has the advantage of requiring a lower voltage than the "cantilever" design, but the drawback is a higher capacitive load. Consequently, the use of the present invention is very suitable. As can be estimated, for example, of the aforementioned patent EP-A-0277703, in such constructions require the electrode in the active part (L) of the channel, passing on the selected designs, that is typically 25 μm and (or) not more than 20% of the height of the wall. In WO 92/09436 describes a laminate from which you can do a "herringbone" design, using essentially the same technology, as discussed above regarding the "console" device.

Fig. 6 is a view in section corresponding to the view of Fig. 2 and illustrating relevant to another aspect of the present invention the printhead, and Fig. 7 illustrate the corresponding types in the context. As with the previous aspect, the design of the active segment printhead remained the same as in conventional heads, with the electrode 26, passing down approximately half the wall of the piezoelectric material in the case shown "console" drive (and the entire height of the wall of the piezoelectric material in the case of drives "herringbone" type).

In contrast, part (N) of the channel full of depth, which is open on one side to the window 27 of the ink and which, consequently, is not part of the "active" section of the channel, different from the usual designs so that a layer of material 40 having a lower dielectric constant than the piezoelectric material placed between S="ptx2">

Capacitive load of the wall of the channel in this part of the channel can now render with more three consecutive capacitors, one capacitor in conventional constructions. As schematically illustrated in Fig. 8, the capacitor C1formed through the layer 40 on both sides of the wall in addition to the capacitor C2formed of the piezoelectric material of the wall 22. Choosing a material having a dielectric constant lower than that of the piezoelectric material, the resulting total capacitance of the serial capacitors1and C2can be done in less than one piezoelectric material. (In the first approximation, the total capacity is determined by the expression 1/Camounts= 1/C2+ 2/C1where it is possible to notice that the low value of C1will give a low value of Camounts).

As is clear from Fig. 7 (C), this method can favorably be used in area C of the connecting tracks, as well as in the field of R release.

As with the previous aspect of the invention, this aspect can be accomplished by using the methods of application, which are known in themselves. As the material having a lower delainey relative dielectric constant, approximately 8 (compared with a value of approximately 3600 for a piezoelectric material such as lead zirconium titanate (PZT)), and is typically used in ink-jet printing head as a protective coating pestiviruses substances for the electrodes of the channel.

This material can be applied on the walls of the channel, using methods known, for example, from WO 95/07820, at the same time keeping the estimated active part L of the channel is masked. The resulting layer of silicon nitride typically has a thickness in the range of 0.3 to 0.5 μm. The application process requires only one mask, placed in such a way as to prevent the application of incoming material with a low dielectric constant on the active segment of the channel. As shown in Fig. 9, the mask 70 must form a tight contact with the upper parts of the walls 22 in the active region L and should be a little over the active part L, usually on the depth of the channel, because the used method of applying causes the penetration of incoming material with a low dielectric constant (indicated by arrows 80) under the overhanging region 72 (indeed, the method of application is intentionally selected because of this property, to fill in order to be conductive, to avoid overheating and deformation during the application process. Thus, usually it is made from aluminum with a thickness of 2-3 mm

Subsequently, the electrodes can be applied along the entire length of the channel in the normal way described above. Actually, it is believed that pestiviruses tool provides a smoother surface for the application of the electrodes than the rough surface of the channel walls, so in the end electrodes in the inactive parts of the channels are less susceptible to fatigue.

As with the previous aspect of the invention, the use of thermoplastic "shoot" film or overlay isolation was sufficient for the removal of the electrode and a material with a low dielectric constant deposited on top of the channel walls. Again, the invention is equally applicable to "console", "herringbone" or any other construction of the printhead, where the piezoelectric material polarized in the direction perpendicular to the layer of piezoelectric material.

Instead of the silicon nitride layer with a low dielectric constant can be used many alternative insulation materials and/or alternative methods of application: oxides, especially in order to ensure the possibility of applying a layer with a low dielectric constant and electrode channel, using a single detail of the device of the application, giving the obvious savings in production time (no need to carry the item with educated channels from one machine to another) and capital equipment. For example, a layer with a low dielectric constant of aluminum nitride can be applied to the element formed by the channels in the chamber by evaporation of aluminum as the bombing of the element nitrogen ions or free radicals. Subsequent pumping chamber provides the opportunity esperavamos aluminum deposited as an electrode on the channel walls in the same chamber method known from the aforementioned patent EP-A-0364136.

It should be understood that the possible changes of the above aspects, while staying within the scope of the patent protection of the present invention. For example, the above-mentioned aspects can be used in combination with the inactive part of the "N" channel with the small electrode and the layer of material with a low dielectric constant, is placed between the electrode and the side wall of the channel. Alternatively, either or both of the above aspects of the invention can be used in combination with other reducing e is relatively shown on drawings: for high frequency operation described in the patent EP-A-0422870 species (and where low capacitive load is particularly important due to the high frequency excitation) may be required segments of active channels (L) in the lower end of the range of 10-1 mm, for example, 4 mm, while the size of the hole collector in the longitudinal direction of the channel may be necessary to leave essentially constant, for example, 10 mm in order to ensure the possibility of occurrence of a sufficient amount of ink without excessive pressure drop or to adapt existing designs ink, etc. So in the end, the present invention is particularly advantageous in printing heads with respect to the inactive segment of the full depth of the active segment with the full depth of approximately 2 or more.

Other critical dimensions such printhead can usually be as follows: the total depth of the channel is 300 μm, the depth of the electrode in the active part of the channel is 150 μm, the width of the canal in paragraphs (L, N) with full depth - 62 μm, the length of part (C) connecting track - 7.4 mm, width of canal wall part connecting tracks - 47 μm, the total length of the drive (C+R+N+L) - 11.5 mm, the length of the active segment (L) - 1,5 mm

It should be understood that in such constructions the use of the present invention results in a larger proportional reduction of the capacitive load of the printhead than the printing heads of the type shown in CE in the inactive part of a single wall of the channel, with the above dimensions, leads to a total capacity for the wall equal to 354 pF, compared with a value of 540 pF for the same wall using the electrode constant height of 150 μm. Use relevant to another aspect of the invention, the film pestiviruses substances with a low dielectric constant gives the total capacity of the wall 190 pF, whereas the use of both in combination gives the value of the vessel wall 140 pF. This value is extremely close to the value represented an active part of one wall (129 pF).

The invention is not limited to the shown on the drawings configurations printhead: in particular, the fluid drops can be fed from either side of the channel, located parallel to the axis of the channel, for example, through the hole in the base of the channel, as shown in the patent EP-A-0364136. Similarly, the nozzle does not need to be placed on the axis of the channel, as shown on the drawings, but may be located in the lid or the base (the so-called "bernastrasse" and "ninestiles" design) or in another place, as is known in the art. Corresponding to the present invention, the device is also not necessarily limited to the manufacture of the historical constant can be taken into account after attaching the top cover to the base with formed channels. Alternatively, the base formed by the channels and the top layer can be included in the individual nodes, each of which is independently subjected to manufacturing.

Of course, it should be understood that the present invention is applicable to methods of manufacturing-type laminated plate and the constructions described, for example, in WO 95/18717. You must properly fit the mask, the passivation and deposition of the electrodes. In those constructions where the ink is served with the end, and not on the side of the channel, for example, from depression 100 collector perpendicular to the longitudinal axis of the channel, as shown in Fig. 10, a material with a low dielectric constant is simply placed between the material 105 and electrode element 110 formed channels in those areas 120, which are located outside the closed (active) parts 130 channels.

The present invention is also applicable to structures containing piezoelectric material polarized different way from the above described constructions and having respectively different location of the stimulating electrodes. An example of this construction is given

in U.S. patent US-A-5235352, which has a separating channel wall, the impact is perpendicular to the polarization direction of the electric field from the electrodes, located in the very walls. Layers with low dielectric constant is applied between the electrodes and the piezoelectric material in those parts of the wall that correspond to inactive, uncovered parts of the channel. Each characteristic disclosed in this description, the term includes the claims and/or shown on the drawings, may be included in the invention independently of the other disclosed and/or illustrated features.

The text of the abstract submitted together with the description, repeated here as part of the description.

Forming droplets of the piezoelectric printhead has a wall of a channel formed of a piezoelectric material (10) with electrodes (26) along their length. In parts of the channels, which are open to the supply channel of the ink, the piezoelectric material is locally blocked, for example, by reducing the width of the electrode or the introduction of material (40) with a lower dielectric constant between the electrode and the piezoelectric material. The result is a lower capacitive load.

1. The device applying droplets containing the lower plate including a piezoelectric material and having a multitude of parallel channels on the Alov, each channel is formed at least partially facing each other, side walls and bottom surface, passing between the side walls, and at least the side walls contain a piezoelectric material and electrodes for application of an electric field to the piezoelectric material for the transverse mixing of the side wall, the top plate facing the bottom surfaces of the channels and attached to the side walls for closing the channels in their upper parts, and the channels configured to supply the fluid medium drops and communicated with a nozzle for releasing from it drops, and each channel has one part, the open side lying parallel to the axis of the channel for communication with means for supplying fluid drops, and another part that is closed on all sides and lying parallel to the axis of the channel, characterized in that the respective side walls including a piezoelectric material in one part of each channel is locked for the release of their transverse mixing one part each channel.

2. The device under item 1, characterized in that one part of each channel layer of material having a dielectric constant lower than that of the piezo is s, placed on opposite sides of walls to block the piezoelectric material.

3. The device under item 1, characterized in that the electrodes are placed in one part of each channel, are on the shorter height of the respective side walls than the electrodes placed in the other part of each channel, for inefficient excitation of the piezoelectric material in one part, with the blocking of this part.

4. The device applying droplets containing the lower plate having a layer of piezoelectric material polarized in a direction perpendicular relative to a layer that contains a multitude of parallel channels with open tops, placed at a distance from each other in the direction perpendicular to the length of the channels, each channel formed at least partially facing each other, side walls and bottom surface, passing between the side walls, with at least the side walls contain a piezoelectric material, an upper plate facing the lower surfaces of the channels and attached to the side walls, for closing the channels in their upper parts, and the channels are made with the possibility of the em one part, the open side lying parallel to the axis of the channel for communication with means for supplying fluid drops, and another part that is closed on all sides and lying parallel to the axis of the channel, the electrodes placed on opposite sides of the side walls, to form actuators shear mode displacement drops of channels connected to the actuators, and each electrode takes place essentially along the entire length of the channel, characterized in that one part of the channel between the piezoelectric material and at least one of the electrodes placed on opposite sides of the side walls, posted by a layer of material having a dielectric constant lower than that of the piezoelectric material.

5. The device according to p. 4, wherein each of the one and the other parts are formed, at least partially, the side walls having coplanar upper surfaces and essentially a constant height, and the height of the respective side walls of one and the other parts are essentially the same.

6. Device according to any one of paragraphs.4 and 5, characterized in that for each channel of the nozzle is adjacent to another part of the channel.

7. Device according to any one of paragraphs.4 to 6, differently the WMD of PP.4 - 7, characterized in that the other part of the electrodes placed on the surface of the piezoelectric material of the respective channel walls.

9. The device under item 8, characterized in that the electrodes placed on opposite sides of the side walls, at least one part of each channel, located at the top of each side wall of the channel remote from the bottom surface.

10. Device according to any one of paragraphs.4 to 9, characterized in that each of the channels contains an additional part with the wall of the channel of less height than the walls of one channel or the other parts, and the electrodes are placed on facing each other, the channel walls and the Foundation of each of the channels and between the electrodes facing each other with the walls and base of each channel is placed a layer of material having a dielectric constant lower than that of the piezoelectric material.

11. A method of manufacturing a device applying droplets containing (a) the formation of multiple parallel channels in the bottom plate containing a layer of piezoelectric material, (b) applying a layer of material, at least one of the facing to each other of the lateral walls of the first h is material, and facing each other, the side walls of the second part of each of the channels free from this material, (C) deposition of electrode material on the facing each other, the side walls of the first and second parts of the channels.

12. The method according to p. 11, characterized in that it contains (d) masking the second portion of each of the channels before applying a layer of material on at least one of the facing to each other of the side walls of the first part of each of the channels, (e) demaskirovanie the second part before applying the electrode material on the facing each other, the side walls of the first and second parts of the channels.

13. The method according to any of paragraphs.11 and 12, characterized in that the electrode material is applied by metal vapor beam aimed at the wall at an angle to the facing to each other surfaces of the channel.

14. The device applying droplets containing the lower plate having a layer of piezoelectric material polarized in the direction perpendicular to the layer containing many parallel channels with open tops, placed at a distance from each other in the direction normal to the length of the channels, each channel formed at least cha the activities passing between the side walls, and at least the side walls contain a piezoelectric material, an upper plate facing the lower surfaces of the channels and attached to the side walls for closing the channels in their upper parts, and the channels configured to supply a liquid fluid medium drops and communicated with a nozzle for releasing from it drops, each channel has one part that is open on the side lying parallel to the axis of the channel for communication with means for supplying fluid drops, and another part that is closed on all sides lying parallel to the axis of the channel electrodes, placed on opposite sides of the side walls for education thereby drives the shear mode displacement drops of channels connected to the actuators, and each electrode takes place essentially along the entire length of the channel, characterized in that the electrodes are placed in one part of each channel, are on the shorter height of the respective side walls than the electrodes placed in the other part of each channel.

15. The device according to p. 14, wherein each of the one and another portions formed at least partially lateral walls, essentially, the A.

16. The device according to p. 15, wherein for each channel the nozzle is placed adjacent to another part of the channel.

17. Device according to any one of paragraphs.14 to 16, characterized in that for each channel one and the other parts are in contact.

18. Device according to any one of paragraphs.14 to 17, characterized in that the electrodes placed on opposite sides of the side walls, at least one part of each channel, are located in the upper part of each side wall of the channel remote from the bottom surface.

19. Device according to any one of paragraphs.14 to 18, characterized in that the electrode is preferably takes place at 10% or less of the height of the corresponding walls of the channel in one part.

20. Device according to any one of paragraphs.14 to 19, characterized in that the electrode is placed in another part, and passes approximately half the depth or essentially the entire depth of the corresponding wall of the channel.

21. Device according to any one of paragraphs.14 to 20, characterized in that the ratio of the segments of one and the other parts of the channel is approximately 2 or more.

22. A method of manufacturing a device applying droplets containing (a) forming in the bottom plate containing layer piezoelectric the e part, (b) applying the material of the electrode facing each other, the side walls of the first part of each of the channels in the first segment of the height of the respective side walls, (C) deposition of electrode material on the facing each other, the side walls of the second part of each of the channels in the second period of the height of the respective side walls, and first and second segments are different in length.

23. The method according to p. 22, characterized in that it contains (d) masking the second portion of each of the channels before applying a layer of electrode material on the facing to each other of the first wall part of each of the channels in the first segment of the height of the respective side walls, (e) demaskirovanie the second part before applying the electrode material on the facing each other, the side walls of the first and second portions of each of the channels.

24. The method according to any of paragraphs.22 and 23, characterized in that the first segment is greater than the second length.

25. The method according to p. 24, characterized in that the second segment does not exceed 10% of the height of the wall.

26. The method according to any of paragraphs. 22 to 25, characterized in that the electrode material is applied using a metal vapor beam aimed at the wall at an angle to facing each Xenia in the second part.

27. The device applying droplets having a bottom plate containing a layer of piezoelectric material polarized in the direction perpendicular to the layer having a multitude of parallel channels with open tops, placed at a distance from each other in the direction perpendicular with respect to the length of the channels, each channel formed at least partially facing each other, side walls having a height and a bottom surface, passing between the side walls, with at least the side walls contain a piezoelectric material, an upper plate, facing the bottom surfaces of the channels and attached to the side walls for closing the channels in their upper parts, and the channels configured to supply the fluid medium droplets and communicated with a nozzle for the outlet of the droplets, and each channel has a part enclosed on all sides and lying parallel to the axis of the channel, the electrodes are placed across the very least, on opposite sides of the side walls for education thereby drives the shear mode displacement drops of channels connected to the actuators, and each electrode takes place essentially along the entire length of the channel is, other than the closed part of each channel is placed a layer of material having a dielectric constant lower than that of the piezoelectric material.

28. The device applying droplets having a lower plate including a piezoelectric material and having a multitude of parallel channels with open tops, placed at a distance from each other in the direction perpendicular to the length of the channels, each channel formed at least partially facing each other, side walls having a height and a bottom surface, passing between the side walls, with at least the side walls contain a piezoelectric material, an upper plate facing the lower surfaces of the channels and attached to the side walls for closing the channels in their upper parts, moreover, the channels configured to supply a liquid fluid medium drops and communicated with a nozzle for the outlet drops, and each channel has a part enclosed on all sides lying parallel to the axis of the channel, the electrodes for application of an electric field to the piezoelectric material in the side walls, characterized in that in areas other than the closed portion of each of the channel material, having a dielectric constant lower than that of the piezoelectric material.

29. The method of coating the surface of the element with channels, each of which has two facing each other, the side walls and the surface between them, in which the coating is applied on the side walls by placing the element in a vacuum chamber, impacts on the side walls of the element beam metal vapor and by switching between the state in which the chamber is under vacuum, and the state in which the side walls of the element is bombarded with ions, or free radicals, and in the condition in which the chamber is under vacuum, the metal vapor beam is directed under a non-zero angle to the walls of the chamber.

30. The method according to p. 29, characterized in that the ions or free radicals are oxygen or nitrogen.

31. The method according to p. 30, characterized in that the metal vapor beam contains evaporated aluminum.

Priority points:

23.04.1996 on PP.1 - 28;

23.11.1996 on PP.29 - 31.

 

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