JP2024091463A - Mounting and positioning means for printhead devices - Patents.com - Google Patents

Abstract

The present invention provides a simple method for droplet ejection devices that does not require subsequent alignment when mounting them in a printer.
[Solution] The method includes providing a carrier (80) having a first flat mounting surface (82), providing a droplet ejection device (10) on the carrier (80) aligned with the first flat mounting surface (82), and providing a plurality of mounting spheres (72) of a predetermined diameter on the first mounting surface (82), each of which is inserted into a circular holder (74) that is fixed to the first mounting surface (82) so that the mounting spheres (72) are in direct contact with the first mounting surface (82).
[Selected figure] Figure 5

Description

The present invention relates to mounting and positioning means for printhead devices.

BACKGROUND OF THEINVENTION 1. Field of the Invention The present invention relates to printhead devices and methods for installing such printhead devices in printers.

2. Description of the Background Art A printhead device comprises at least one dropletjetting device. When multiple printhead devices are applied in a printer, they require alignment relative to one another to ensure a correct position of the ink drops on the print medium. It is known to provide printhead devices with mounting and positioning means that aid in the alignment of the printhead device relative to a stationary frame of the printer. Known mounting and positioning means may comprise mounting spheres and/or adjustment screws for aligning the printhead device relative to a horizontal surface, as known for example from US Pat. No. 7,401,899. Adjusting the mounting and positioning means during mounting of the printhead device is, however, time consuming. Furthermore, it has been found that during operation the initial alignment of known mounting and positioning means may be lost or reduced.

SUMMARY OF THE PRESENT DISCLOSURE It is an object of the present invention to provide an improved method of mounting and positioning a printhead device.

According to the invention there is provided a method for mounting a printhead according to claim 1, a printhead device according to claim 6 and a printer according to claim 15.
The method is:
providing a carrier having a first planar mounting surface;
providing a droplet ejection device on the carrier aligned with the first planar mounting surface;
providing a plurality of mounting spheres of a predetermined diameter on the first mounting surface, each mounting sphere being inserted into a circular holder that is adhered to the first mounting surface such that the mounting spheres directly contact the first mounting surface.

The diameter of each mounting sphere is pre-determined with high accuracy, for example by applying so-called high accuracy or high precision spheres that can be formed with very high accuracy. Each mounting sphere is fixed to the carrier so that it directly contacts the first mounting surface. Since the droplet ejection device is aligned with respect to the first mounting surface, the mounting sphere is aligned with the first mounting surface and, consequently, with the droplet ejection device upon contact. The highest point of each mounting sphere is furthermore precisely defined with respect to the first mounting surface and, consequently, with the droplet ejection device. Thus, the printhead device can be easily aligned by mounting and positioning the mounting spheres in suitable predetermined receivers. For example, if all mounting spheres have the same diameter and the receivers are aligned horizontally, the droplet ejection devices of the printhead device can be aligned horizontally when the printhead device is mounted on the receiver. No additional adjustments are required. An additional advantage is that the proposed method is relatively simple and low-cost to implement. Thus, the object of the present invention has been realized.

Further specific additional features of the present invention are set forth in the dependent claims.

In one embodiment, preparing the carrier comprises forming a second flat mounting surface on the carrier parallel to the first flat mounting surface of the carrier, and applying the droplet ejection devices comprises mounting the droplet ejection devices on the second flat mounting surface. To allow a compact printhead device that can be placed in close proximity to the print medium without contacting it, the carrier is preferably provided with opposing mounting surfaces on the carrier. The carrier is preferably of flat construction so that two precise, flat and parallel mounting surfaces can be formed with very high precision, for example by double-sided abrasion. The droplet ejection devices are mounted on the second mounting surface. By aligning the droplet ejection devices to the second mounting surface, they are aligned to the first mounting surface and, therefore, to the mounting spheres. The alignment is 'preserved' so that no adjustments are required to position the droplet ejection devices after they are attached to the receiver. Planar, as used herein, will be understood to define a flat or smooth surface at least where the mounting balls contact the carrier. The mounting surface is planar, meaning that it is substantially free of indentations or recesses, at least at the locations of the mounting balls. Preferably, the mounting surface is defined by a single plane, such that the contact areas all lie in the same plane with the mounting balls.

In one embodiment, the method further comprises mounting the printhead device on a printhead support of a printer, the printhead support comprising a plurality of receivers, the mounting balls being located in their respective receivers. The receivers are connected to a frame of the printer in predetermined positions with high accuracy. In a preferred embodiment, the different receivers are mounted such that their receiving surfaces are located in the same horizontal plane during use. If mounting balls of the same diameter are then applied, the first mounting surface and the droplet ejection device are aligned horizontally when the mounting balls are inserted into the receivers.

In one embodiment, the mounting balls are formed of a ceramic material and have the same diameter. Ceramic spheres or balls are commercially available with high accuracy of diameter. Such balls are commonly formed of metal oxides, such as zirconia, alumina, silica, etc. The metal-oxide composition further ensures high hardness and rigidity, ensuring that the mounting balls maintain their shape during manufacture and operation. It will be further appreciated that the coefficient of friction between the mounting balls and their receivers on the printer is relatively low to allow sliding contact to allow (re-)positioning the mounting balls. Preferably, the ceramic material is or comprises alumina (Al ₂ O ₃ ).

In one embodiment, each holder and corresponding mounting ball, in their assembled state, have circular symmetry with respect to an axis perpendicular to the first flat mounting surface. Each mounting ball and its holder appear identical when viewed above and below the first mounting surface and when rotated to any angle. The holder is preferably ring-shaped, and when viewed from above, the mounting ball and its holder appear as a ring with the mounting ball received in the center. The circular symmetry ensures continuous accurate alignment during operation, when the print head device heats up and the mounting ball and/or holder experience thermal expansion. The mounting ball and holder are each circularly symmetric and their thermal expansion is substantially the same in all directions parallel to the first mounting surface. As a result, thermal expansion, stresses, strains and deformations are the same in all directions parallel to the first mounting surface, so that alignment accuracy is not affected. The droplet ejection devices are therefore not shifted in position due to heating within the print head device.

In a further aspect, the invention relates to a printhead device comprising at least one droplet ejection device arranged on a carrier, the carrier comprising a plurality of mounting surface areas provided in fixed, predefined positions and orientations relative to each other and to the at least one droplet ejection device, a mounting sphere with a predefined radius being attached to each mounting surface area, each mounting sphere being held in direct contact with the corresponding mounting surface area by means of a corresponding holder. Each mounting sphere is directly located on the corresponding mounting surface area. The mounting surface areas have a precisely defined positional relationship to each other. In one example, the mounting surface areas are all located in a single flat plane. In more complex embodiments, the mounting surface areas can be provided out of plane with each other, but their relative position vectors are precisely predetermined, for example by forming the different areas with a precise process, such as MEMS processing. Since the mounting sphere has a precise, predefined diameter, the positional relationship between the top of the mounting sphere and the at least one droplet ejection device is precisely defined. Thus, by mounting the mounting sphere on a pre-positioned receiver, the printhead device can be precisely positioned with respect to the receiver. Preferably, all mounting spheres have the same radius, and the plane defined by their highest points (measured from their mounting surface areas) is parallel to the plane defined by said mounting surface areas. If the mounting surface areas are located in the same plane, for example by being part of a single first mounting surface, then mounting spheres of the same diameter ensure that the plane defined by their apexes is parallel to said plane, which is also parallel to the droplet ejection device. By mounting the mounting spheres on the receiver, the droplet ejection device can be aligned parallel to the plane defined by the receiver, which is preferably horizontal.

In one embodiment, each holder extends fully circumferentially around the corresponding mounting sphere. The holders, such as the mounting fixtures, are preferably circularly symmetric when viewed perpendicular to the respective mounting surface area. This ensures that thermal expansion affects each holder and mounting sphere circularly symmetrically, thereby reducing the chance of shifting of the droplet ejection device due to thermal effects. In one preferred embodiment, each holder is a clamping ring. The clamping ring has a central opening with a cross-sectional diameter slightly smaller than that of the corresponding mounting sphere. This allows the mounting sphere to be safely attached to the holder in a simple and reliable manner, for example by pressing. Preferably, the mounting sphere is inserted into the holder so that it extends beyond the mounting surface on the side of the holder opposite the mounting surface area after assembly.

In one embodiment, each clamp ring is secured to a corresponding mounting surface area with an adhesive. The adhesive is applied between the mounting surfaces of the holder, which face the mounting surface areas on the carrier. The area or zone where the mounting ball should contact the mounting surface area is free of adhesive, providing direct contact between the two. Adhesive is preferably applied around the perimeter, but not within this contact area.

In one embodiment, all mounting surface areas are located in a single flat plane on the first flat mounting surface of the carrier. The flat plane is a plane or line that defines a single first mounting surface and comprises all mounting surface areas. The first mounting surface can be easily and accurately formed, for example by grinding. By forming all mounting surface areas on the carrier as a single first mounting surface, the mounting surface areas are easily aligned with each other. If combined with mounting spheres of the same diameter, an easy mounting and positioning means is realized that accurately transfers the alignment of the droplet ejection device.

In one embodiment, the carrier further comprises a second flat mounting surface parallel to the first flat mounting surface, on which the droplet ejection device is mounted. The second mounting surface is preferably on the opposite side of the carrier to create a space-efficient printhead device, allowing the droplet ejection device to be positioned closer to the print medium (so-called small print gap spacing). Parallel and accurate first and second mounting surfaces can be easily formed, for example, by double-sided abrasion of the carrier. The carrier is preferably formed as a flat structure, with the first and second mounting surfaces being the largest surfaces on the opposite carrier. The droplet ejection device is mounted on the second mounting surface in registration therewith. As a result, the droplet ejection device is precisely aligned with the first mounting surface, and then with the mounting ball and receiver, which are also mounted.

In one embodiment, the printhead device according to the invention comprises three mounting spheres. To achieve positional stability, preferably three mounting spheres are applied as mounting and positioning means. Additional means for fixing the printhead device on the receiver may be provided, but these preferably only incur a holding force perpendicular to the first mounting surface, whereas the position of the printhead device relative to the receiver is entirely determined by the mounting spheres. In one embodiment, the mounting spheres are made of a ceramic material.

A further aspect of the invention relates to a printer comprising a printhead device as described above. The printer preferably comprises a plurality of said printhead devices, for example to form a page-width printhead array. By applying the above-described method or design, the different printhead devices, and in particular their droplet ejection devices, can be easily and accurately aligned with each other and/or to the same horizontal plane during use.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration only, and various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be more fully understood from the detailed description given below and the accompanying drawings, which are given by way of example only and are not intended to be limiting thereof:
FIG. 1 is a schematic cross-sectional view of a droplet ejection device for a printhead device;
FIG. 2 is a schematic cross-sectional view of a carrier of a droplet ejection device with the droplet ejectors mounted and aligned on the carrier;
FIG. 3 is a schematic cross-sectional view of the carrier of FIG. 2 in a step of mounting and positioning means on the carrier;
FIG. 4 is a schematic cross-sectional view of the carrier of FIG. 3, in which mounting and positioning means are secured onto the carrier;
FIG. 5 is a schematic cross-sectional view of the carrier of FIG. 4 during the step of placing the mounting and positioning means in a corresponding holder in a printer; and
FIG. 6 is a schematic cross-sectional view of the carrier of FIG.

DETAILED DESCRIPTION OF THE REFERENCED EMBODIMENTS The present invention may now be described with reference to the accompanying drawings, in which like reference numerals are used to identify the same or similar elements in the several drawings.

Droplet Ejection Device Figure 1 shows a single droplet ejection device 10 which is one of a number of ejection devices having the same design and integrated into a common MEMS chip which may be used, for example, in an inkjet printhead. The MEMS chip, and thus the ejection device 10, has a layered structure comprising as main layers a distribution layer 12, a membrane layer 14 and a nozzle layer 16. Such a droplet ejection device 10 is known from US Pat. No. 1,039,768, the description of which is incorporated herein by reference.

The distribution layer 12 is a single silicon layer having a relatively large thickness of at least 400 microns. It defines ink supply lines 18 through which liquid ink is supplied from an ink reservoir 19 to pressure chambers 20 formed in the bottom surface of the membrane layer 14. The ink reservoir 19, which is diagrammatically illustrated in FIG. 1, is common to several jetting devices and is formed separately from the distribution layer 12, at the top surface of the separation layer, i.e. opposite the membrane layer 14. This has the advantage that the separation layer 12 is not weakened by any cavities forming the reservoir.

The membrane layer 14 is obtained from an SOI wafer having an insulator layer 22 and silicon layers 24 and 26 formed on both sides thereof. In this embodiment, the final membrane layer 14 may have a thickness of about 75 microns. The pressure chamber 20 is formed in the bottom silicon layer 26. The top silicon layer 24 and the insulator layer 22 form a continuous flexible membrane 30 with uniform thickness, which extends over the entire area of the MEMS chip and is pierced with openings 28 only at the locations of the ink supply lines 18 to connect to the ink supply lines to the pressure chamber 20. A piezoelectric actuator 32 is formed on the upper surface of the portion of the membrane 30 covering the pressure chamber 20. The actuator 32 is housed in an actuator chamber 34 formed on the bottom side of the distribution layer 12.

An electrically insulating silicon oxide layer 36 insulates the actuator 32 and its electrodes from the silicon layer 24 and carries leads 38 arranged to contact the electrodes on the top and bottom of the actuator 32. The leads 38 are exposed and accessible at contact areas 40 where the distribution layer 2 has been removed.

The nozzle layer 16 is obtained from a double SOI wafer and has a top silicon layer 42 and a thinner silicon layer 44 interposed between two insulator layers 46 and 48. The nozzle 50 is formed in the two insulator layers 46 and 48 and the interposed silicon layer 44, the thicknesses of these three layers defining the length of the nozzle. The top silicon layer 42 of the nozzle layer 16 defines a feedthrough 52 that connects the pressure chamber 20 to the nozzle 50, but has a cross section significantly larger than that of the nozzle 50.

It will be appreciated that the MEMS chip droplet ejection device 10 is arranged such that its nozzles 50 define, for example, a nozzle array consisting of one, two or more parallel rows of nozzles with uniform nozzle-to-nozzle spacing that determines the spatial resolution of the printhead. Within the contact area 40, each of the leads 38 can be contacted such that energizing signals in the form of electrical voltage pulses can be applied individually to each actuator 32, for example via bumps 54. When a voltage is applied to the electrodes of the actuators 32, the piezoelectric material of the actuators is deformed into a bending mode, thereby flexing the membrane 30 and thus changing the volume of the pressure chamber 20. Typically, a voltage pulse is applied to the actuator to cause a deformation that increases the volume of the pressure chamber 20, and ink is sucked from the supply line 18. Then, when the voltage pulse is reduced or changed to a pulse of the opposite polarity, the volume of the pressure chamber 20 decreases suddenly, creating an acoustic pressure wave that propagates through the pressure chamber 20 and through the feedthrough 52 to the nozzle 50, with the result that a droplet of ink is ejected from the nozzle 50.

When the actuator 32 performs a suction stroke, ink is sucked from the ink supply line 18, while capillary forces in the nozzle 50 prevent ambient air from entering through the nozzle. Then, during the subsequent compression stroke of the actuator 32, the acoustic pressure that ejects the ink from the nozzle 50 must overcome the capillary forces in the nozzle, as well as the frictional forces that are generated in the nozzle 50 and in the feedthrough 52 due to the specific viscosity of the liquid ink. The ink supply line 18 must be designed so that, regardless of these resistances, most of the ink is pushed out as droplets through the nozzle 50 rather than only pushed back into the ink supply line 18. To that end, the ink supply line 18 is designed to have a certain inertance, so that the inertia of the liquid entering during the suction stroke compensates for the forces that tend to urge the liquid in the opposite direction during the compression stroke.

In the illustrated example, the restrictor 56 extends between a trench 58 and a restrictor cavity 60, which form the end part of the ink supply line 18, and which are formed on the top and bottom surfaces of the distribution layer 12, respectively. This allows the length L of the restrictor 56 to be selected independently of the total thickness of the distribution layer 12. Nevertheless, the length L of the restrictor can be controlled with high precision since the total thickness of the distribution layer 12 is known or can be measured with high precision, and the respective depths of the trench 58 and the restrictor cavity 60 can be precisely determined by controlling the etching time when the trench and/or the restrictor cavity are formed by etching.

As shown in FIG. 1, the distribution layer 12 is connected to the membrane layer 14 by a bonding layer 62. Similarly, the membrane layer 14 is connected to the nozzle layer 16 by a bonding layer 64.

A number of droplet ejection devices 10 are mounted in a printer to form a printhead array. Different droplet ejection devices 10 need to be aligned with each other in terms of position and orientation to ensure that the ejected droplets are deposited accurately. Misalignment of a droplet ejection device 10 with respect to the others can result in visible print artifacts in the print. Thereto, one or more droplet ejection devices 10 are provided on a carrier 80, provided with mounting and positioning means 70 for accurately mounting at least one droplet ejection device 10 in the printer. Figures 2 to 5 show the steps of a simple, low-cost and accurate method for positioning a droplet ejection device 10 in a printer.

Mounting and Positioning Means FIG. 2 illustrates the steps of providing a carrier 80 and mounting at least one droplet ejection device 10 thereon. The carrier 80 comprises two planar mounting surfaces 82, 84 that are parallel to one another. The top and bottom mounting surfaces 82, 84 are aligned with one another and are both processed to have a high degree of flatness. The mounting surfaces 82, 84 are very flat and are very precisely aligned with one another and are parallel. In the example of FIG. 3, the carrier 80 is preferably formed of a ceramic substrate that is processed by grinding, specifically double-sided grinding, to form the two flat, parallel mounting surfaces 82, 84. Double-sided grinding is an accurate, relatively low-cost, and efficient method of forming the two parallel mounting surfaces 82, 84 on the carrier 80. Suitable materials for the carrier 80 may include metal oxides or other suitable hard materials.

One of the flat mounting surfaces 82, 84 is arranged to mount the droplet ejection device 10 thereon, whereas the other of the mounting surfaces 82, 84 is designed to hold the mounting and positioning means 70. The droplet ejection device 10 preferably also has its own flat mounting surface, allowing the droplet ejection device 10 to be accurately mounted on the corresponding carrier 80. This allows the different droplet ejection devices 10 to be accurately aligned on the carrier 80, as shown in FIG. 6. The droplet ejection devices 10 are mounted on the second mounting surface 84 (bottom surface in FIG. 2) of the carrier 80 such that each droplet ejection device 10, specifically the row of nozzles 50, is parallel to the second mounting surface 84 of the carrier 80. In the mounted state, the ink supply lines 18 of the droplet ejection devices 10 are fluidly connected to corresponding distribution channels 86 in the carrier 80, allowing fluid to be distributed through the carrier 80 to all mounted droplet ejection devices 10.

3 shows the step of applying the mounting and positioning means 70. The mounting and positioning means 70 comprises a mounting sphere 72 in a holder 74. The mounting sphere 72 is in the shape of a ball formed with high roundness. Preferably, the mounting sphere is formed of a ceramic material, such as a metal oxide. Commonly used materials include zirconia, alumina, glass (silicon oxide), etc. Such mounting spheres 72 are commercially available as "(high) precision balls" or "(high) precision balls" and can be precisely formed by processes known in the state of the art, such as, for example, V-groove plate methods, including concentric, eccentric, and/or spiral V-groove plate methods, controllable ball-spin angle methods, magnetic abrasive slurry processing methods, etc. The mounting sphere 72 is further formed with a high precision diameter, and its roundness is precisely the same over the entire surface of the mounting sphere 72.

The mounting ball 72 is fixed in its holder 74 in FIG. 3. The holder 74, as seen in FIG. 6, has an annular clamping ring, which extends around the entire circumference of the mounting ball 72 after assembly. The holder 74 has a circular symmetry about an axis parallel to the direction in which the mounting ball 72 is inserted into the holder 74. The holder 74 has a central opening for receiving the mounting ball 74 therein. The central opening 74 has a circular cross section with an initial diameter slightly smaller than the predetermined diameter of the mounting ball 72. The mounting ball 72 is pressed into the central opening of the holder 74 in FIG. 3 so that the mounting ball 72 is clamped and thereby fixed in the holder 74. Heating and cooling can be applied to facilitate insertion and/or improve clamping. The mounting ball 72 is pressed into the holder 74 so that its contact portion 73 extends beyond the mounting surface 76 of the holder 74. The holder 74 may be made of any suitable material, such as metal, ceramic, etc.

4 shows the step of fixing the mounting ball 72 on the carrier 80. Adhesive 78 is provided on the mounting surface 76 of the holder 74 or on a corresponding area of the first mounting surface 82 of the carrier 80. The adhesive 78 is applied such that the contact portion 73 of the mounting ball 72 is free of adhesive 78. The mounting ball 72 is then in direct contact with the first mounting surface 82 of the carrier 80: there is no adhesive 78 between the contact portion 73 and the first mounting surface 82. The holder 74 is fixed to the first mounting surface 82 by the adhesive 76. The adhesive 78 may be further treated by curing, annealing and/or heating to promote a strong bond of the holder 74 to the carrier 80. The mounting ball 72 clamped in the holder 74 is thereby fixed to the carrier 80. Because the contact portions 73 of the mounting spheres 72 are in direct contact with the first mounting surface 82 and the diameters of the mounting spheres 72 have been determined with high accuracy, a highly accurate mounting and positioning means is formed. The heights of the mounting spheres 72 measured perpendicular to the second surface 82 are equal to the diameters of the mounting spheres 72 which have been formed with high accuracy. The plane defined by the tops of the mounting spheres 72 is then also accurately defined. In this example, because all the mounting spheres 72 have the same diameter, this plane is parallel to the first and second mounting surfaces 82, 84 and to the droplet ejection device 10. The heights of the mounting spheres 72 measured perpendicular to the first mounting surface 82 are thus determined with high accuracy, but the in-plane positions of the mounting spheres 72 parallel to the first mounting surface 82 do not need to be determined with the same degree of accuracy in this step. For example, the holder 74 may be secured using a known glue mold or glue template. The mounting spheres 72 and their holders 74 are first mounted on the carrier 80. In a subsequent step, the droplet ejection device 10 is mounted on the carrier 80 based on the position of the mounting spheres 72. In this example, the in-plane position of the droplet ejection device 10 is aligned with respect to the mounting spheres 72 already fixed to the carrier 80. This allows for easy and quick attachment of the mounting spheres 72 and holders 74. The droplet ejection device 10 can be accurately positioned using known alignment processes, for example from MEMS processing.

It will be appreciated that in other embodiments, the holder 74 may first be glued to the carrier 80, and then the mounting ball 72 is pressed into the holder 74. The adhesive 78 may be applied to the first mounting surface 82, the holder 72, or both, as long as it is ensured that the contact portion 73 of the mounting ball 72 is free of adhesive 78 in the assembled state, and is in direct contact between the mounting ball 72 and the first mounting surface 82.

In FIG. 5, the mounting and positioning means are positioned within their corresponding receivers 92. The receivers 92 are precisely positioned on the frame 90 of the printer. The frame may be in the form of a printhead support that spans the page width across the printing area of the printer. Each receiver 92 has a receiving surface 94 against which the mounting balls 72 press. Locking means (not shown) ensure that the mounting balls 72 remain in contact with their receivers 92. In this example, the receivers 92 are mounted aligned in the same horizontal plane.

Since the diameter of the mounting spheres 72 is determined very precisely, the distance between the receiver 94 and the second surface 82 is also determined precisely. This is true for all mounting and positioning means shown in FIG. 6: for all mounting spheres 72, the distance between the corresponding receiver 92 and the second surface 82 is then determined by the diameter of the mounting sphere 72. If all mounting spheres 72 have the same precise diameter, this ensures that the second surface 82 is parallel to the plane defined by the receiver 92. Due to the fact that the first surface 84 is parallel to the second surface 82 and the droplet ejection device 10 is mounted parallel to the second surface 82, this has the consequence that the droplet ejection device becomes precisely aligned to the printhead support frame 90 of the printer. There is no need to adjust the mounting and positioning means to ensure alignment. In this example, the receivers 92 are aligned in the same (horizontal) plane and all mounting spheres 72 have the same diameter. When the mounting ball 72 and the receiver 92 are in contact, the droplet ejection device 10 is parallel to the plane defined by the receiver 92. Precise alignment is achieved without the need for further adjustments or tuning.

An additional advantage of the present invention is its continued accuracy during operation. Heat generated within the printhead causes the mounting and positioning means to heat, resulting in thermal expansion of the mounting and positioning means. The mounting and positioning means is formed with circular symmetry about an axis perpendicular to the second face 82 in FIG. 6. As a result, the mounting and positioning means expands evenly in all in-plane directions in FIG. 6, thereby preventing a shift in the position of the droplet ejection device 10 as the operating temperature increases.

While specific embodiments of the present invention have been illustrated and described herein, those skilled in the art will recognize that various alternative and/or equivalent implementations exist. It should be understood that the exemplary embodiment or exemplary embodiments are merely examples and are not intended to be limiting in any way in scope, application or configuration. Rather, the foregoing summary and detailed description may provide one skilled in the art with a convenient road map for implementing at least one exemplary embodiment, and it will be understood that various changes may be made in the function and arrangement of elements described in the exemplary embodiments without departing from the scope as set forth in the appended claims and their legal equivalents. In general, the present application is intended to cover any adaptations or variations of the specific embodiments discussed herein.

In this specification, the terms "comprise", "comprises", "includes", "includes", "contains", "containing", "has", "having", and variations thereof are to be understood in an inclusive (i.e., non-exclusive) sense, and the processes, methods, devices, apparatuses, or systems described herein may include, but are not limited to, features or portions or elements or steps thereof, other elements, features, portions or steps not expressly listed or inherent in such processes, methods, articles, or apparatuses. Furthermore, singular terms ("a" and "an") used herein are intended to be understood as one or more, unless expressly stated otherwise. Furthermore, terms such as "first", "second", "third", etc. are used merely as labels, and are not intended to impose numerical requirements on their objects or to establish a particular order of importance.

The present invention having thus been described, it will be apparent that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications which would be apparent to one skilled in the art are intended to be included within the scope of the following claims.

Claims (15)

1. A method of installing a print head device, comprising the steps of:
providing a carrier (80) having a first flat mounting surface (82);
providing a droplet ejection device (10) on the carrier (80) aligned with respect to the first planar mounting surface (82);
providing a plurality of mounting balls (72) of a predetermined diameter on said first mounting surface (82);
Each mounting ball (72) is inserted into a circular holder (74)
The holder (74) is fixed to the first mounting surface (82) such that the mounting ball (72) is in direct contact with the first mounting surface (82).
Method. 2. The method of claim 1,
applying the carrier (80) comprises forming a second planar mounting surface (84) on the carrier (80) parallel to the first planar mounting surface (82) of the carrier (80);
The method of claim 1, wherein applying the droplet ejection device (10) comprises mounting the droplet ejection device (10) on the second planar mounting surface (84). 2. The method of claim 1,
and mounting the printhead device on a printhead support (90) of a printer,
the printhead support comprises a plurality of receivers (92), and the mounting balls (72) are disposed within corresponding receivers (92). 2. The method of claim 1,
The mounting balls (72) are formed of a ceramic material and have the same diameter. 2. The method of claim 1,
each holder (74) and corresponding mounting sphere (72), in their assembled state, has circular symmetry about an axis perpendicular to said first planar mounting surface (82). A printhead device comprising at least one droplet ejection device (10) disposed on a carrier (80), the carrier (80) comprising a plurality of mounting surface areas provided in fixed, predetermined positions and orientations relative to one another and to the at least one droplet ejection device (10), a mounting sphere (72) with a predetermined radius is attached to each mounting surface area, and each mounting sphere (72) is held in direct contact with a corresponding mounting surface area using a corresponding holder (74). 7. A print head device according to claim 6,
All mounting spheres (72) of the printhead device have the same radius. 7. A print head device according to claim 6,
Each holder (74) extends circumferentially around a corresponding mounting sphere (72) of the printhead device. 9. A print head device according to claim 8,
Each holder (74) is a clamp ring for a print head device. 10. A print head device according to claim 9,
Each clamp ring is secured with an adhesive to a corresponding mounting surface area of the printhead device. 7. A print head device according to claim 6,
All mounting surface areas are located in a single flat plane on the first flat mounting surface (82) of the carrier. 12. A print head device according to claim 11,
The carrier (80) further comprises a second planar mounting surface (84) parallel to the first planar mounting surface (82) on which the at least one droplet ejection device (10) is mounted. 7. A print head device according to claim 6,
A printhead device with three mounting spheres (72). 14. A print head device according to claim 13,
The mounting ball (72) is formed of a ceramic material. A printer comprising a print head device according to any one of claims 6 to 14.

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