KR20030024675A - Ink jet printhead having a moving nozzle with an externally arranged actuator - Google Patents

Abstract

The nozzle assembly 10 for an ink jet printhead includes a substrate 16. At least one nozzle 22 forming a nozzle opening is disposed on the substrate 16. The nozzle opening 24 is connected to the nozzle chamber 34. The nozzle 22 may be moved relative to the substrate 16 to eject ink from the nozzle chamber 34 through the nozzle opening 24 as needed. An actuator 28 is arranged outside the nozzle 22 and is connected with the nozzle 22 to control the displacement of the nozzle 22.

Description

INJ JET PRINTHEAD HAVING A MOVING NOZZLE WITH AN EXTERNALLY ARRANGED ACTUATOR}

US patent application Ser. No. 09 / 112,821, co-filed by the applicant, generally shows a moving nozzle. Such moving nozzle mechanism is driven by means for magnetically responding to eject ink by displacing the moving nozzle.

The problem with this configuration is that the parts of the instrument must be treated to be hydrophobic to prevent ink from entering the part of the actuator.

When it is necessary to avoid the hydrophobic treatment described above, a moving nozzle type mechanism has been proposed.

The present invention relates to an ink jet printhead. More particularly, the present invention relates to an ink jet printhead having a nozzle array, each nozzle having an actuator and a moving nozzle arranged externally.

(Applications filed together)

Various methods, systems and apparatuses associated with the present invention are described in the following pending applications. The following applications are filed concurrently with the present application by the applicant or assignee of the present invention

PCT / AU00 / 00518, PCT / AU00 / 00519, PCT / AU00 / 00520, PCT / AU00 / 00521,

PCT / AU00 / 00522, PCT / AU00 / 00523, PCT / AU00 / 00524, PCT / AU00 / 00525,

PCT / AU00 / 00526, PCT / AU00 / 00527, PCT / AU00 / 00528, PCT / AU00 / 00529,

PCT / AU00 / 00530, PCT / AU00 / 00531, PCT / AU00 / 00532, PCT / AU00 / 00533,

PCT / AU00 / 00534, PCT / AU00 / 00535, PCT / AU00 / 00536, PCT / AU00 / 00537,

PCT / AU00 / 00538, PCT / AU00 / 00539, PCT / AU00 / 00540, PCT / AU00 / 00541,

PCT / AU00 / 00542, PCT / AU00 / 00543, PCT / AU00 / 00544, PCT / AU00 / 00545,

PCT / AU00 / 00547, PCT / AU00 / 00546, PCT / AU00 / 00554, PCT / AU00 / 00556,

PCT / AU00 / 00557, PCT / AU00 / 00558, PCT / AU00 / 00559, PCT / AU00 / 00560,

PCT / AU00 / 00561, PCT / AU00 / 00562, PCT / AU00 / 00563, PCT / AU00 / 00564,

PCT / AU00 / 00565, PCT / AU00 / 00566, PCT / AU00 / 00567, PCT / AU00 / 00568,

PCT / AU00 / 00569, PCT / AU00 / 00570, PCT / AU00 / 00571, PCT / AU00 / 00572,

PCT / AU00 / 00573, PCT / AU00 / 00574, PCT / AU00 / 00575, PCT / AU00 / 00576,

PCT / AU00 / 00577, PCT / AU00 / 00578, PCT / AU00 / 00579, PCT / AU00 / 00581,

PCT / AU00 / 00580, PCT / AU00 / 00582, PCT / AU00 / 00587, PCT / AU00 / 00588,

PCT / AU00 / 00589, PCT / AU00 / 00583, PCT / AU00 / 00593, PCT / AU00 / 00590,

PCT / AU00 / 00591, PCT / AU00 / 00592, PCT / AU00 / 00584, PCT / AU00 / 00585,

PCT / AU00 / 00586, PCT / AU00 / 00594, PCT / AU00 / 00595, PCT / AU00 / 00596,

PCT / AU00 / 00597, PCT / AU00 / 00598, PCT / AU00 / 00516, PCT / AU00 / 00517,

PCT / AU00 / 00511, PCT / AU00 / 00501, PCT / AU00 / 00502, PCT / AU00 / 00503,

PCT / AU00 / 00504, PCT / AU00 / 00505, PCT / AU00 / 00506, PCT / AU00 / 00507,

PCT / AU00 / 00508, PCT / AU00 / 00509, PCT / AU00 / 00510, PCT / AU00 / 00512,

PCT / AU00 / 00513, PCT / AU00 / 00514, PCT / AU00 / 00515

The contents disclosed in these co- filed applications are cross-referenced and incorporated into the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying schematic drawings.

1 is a three-dimensional schematic diagram of a nozzle assembly for an ink jet printhead according to the present invention;

2 to 4 are three-dimensional schematics for explaining the operation of the nozzle assembly of FIG. 1;

5 is a three dimensional view of the nozzle arrangement forming the ink jet printhead;

FIG. 6 is a partial enlarged view of the FIG. 5 arrangement; FIG.

7 is a three dimensional view of an ink jet printhead including a nozzle guard;

8A to 8R are three-dimensional views showing the fabrication process of the nozzle assembly of the ink jet printhead;

9a to 9r are side cross-sectional views showing the fabrication process;

10A-10K are layout views of masks used in various processes of the fabrication process;

11A-11C are three-dimensional views illustrating the operation of a nozzle assembly constructed in accordance with the methods of FIGS. 8 and 9;

12A-12C are side cross-sectional views illustrating the operation of nozzle assemblies fabricated in accordance with the methods of FIGS. 8 and 9.

According to the present invention, there is provided an ink jet printhead comprising the following components.

Substrate;

A nozzle opening is formed on the substrate, the nozzle opening is connected to the nozzle chamber, and at least one nozzle is required to eject ink from the nozzle chamber to the nozzle opening if necessary. At least one nozzle adapted to be movable relative to the substrate; And

An actuator disposed outside the nozzle and connected to the nozzle for controlling the displacement of the nozzle.

The term "nozzle" is to be understood herein as not the opening itself but as an element forming the opening.

The nozzle may include a crown portion forming an opening and a skirt portion connected to the crown portion and forming a first portion of a peripheral wall of the nozzle chamber.

The print head may include an ink inlet hole forming a bottom of the nozzle chamber and a protrusion wall surrounding the hole and forming a second portion of the peripheral wall of the nozzle chamber. It should be understood that the skirt portion can be moved relative to the substrate, and in particular can be moved towards and away from the substrate to effect ink injection and filling of the nozzle chamber, respectively. Thus, the protruding wall can function as a prevention means for preventing ink leakage from the nozzle chamber. Preferably, the protruding wall performs a leakage preventing function and has an edge portion or a wiper portion facing inwardly. This is to prevent the ink from being ejected due to the viscosity of the ink and the gap between the edge portion and the skirt portion when the nozzle moves toward the substrate.

Preferably, the actuator is a thermal bend actuator. The thermal bend actuator may be composed of two beams, an active beam and a passive beam. By "active beam" is meant that no current flows through the passive beam, while current is generated by the actuation of the actuator to flow through the active beam. It will be understood that due to the structure of the actuator, a phenomenon in which current is expanded by the heat of resistance occurs when flowing through the active beam. Since the passive beam is constrained, a bending action occurs in the connecting member in order to displace the nozzle.

The beams may be fixed to an anchor, one end of which is fixed to the substrate and extends upwardly therefrom, the other end of which is fixed to the connecting member. The connecting member may include an arm having a nozzle connected to one end connected to the actuator and an opposite end of the arm in a cantilever shape. Thus, the bending moment at one end of the arm is enlarged at the opposite end to move the nozzle as needed.

The printhead may comprise a plurality of nozzles arranged on a substrate and each having an actuator and a connecting member connected thereto. Each nozzle may form a nozzle assembly with an actuator and connecting member connected thereto.

The printhead may be a planar integral deposition, lithography and etching process, and more particularly, the nozzle assembly may be formed on the printhead by these processes.

The substrate may include an integrated drive circuit layer. The integrated driver circuit layer may be formed using a CMOS fabrication process.

Referring first to FIG. 1, a nozzle assembly according to the present invention is generally indicated by reference numeral 10. The ink jet printhead has a plurality of nozzle assemblies 10 arranged in an array 14 on a silicon substrate 16. The arrangement 14 will be described in more detail below.

The assembly 10 includes a silicon substrate or wafer 16 coated with a dielectric layer 18. A CMOS passivation layer 20 is coated on the dielectric layer 18.

Each nozzle assembly 10 includes a nozzle 22 having a nozzle opening 24, a connecting member in the form of a lever arm 26, and an actuator 28. The lever arm 26 connects the actuator 28 to the nozzle 22.

As shown in detail in FIGS. 2 to 4, the nozzle 22 includes a crown portion 30 and a skirt portion 32 connected to the crown portion. The skirt portion 32 forms a part of the peripheral wall of the nozzle chamber 34 (see Figs. 2 to 4). The nozzle opening 24 is connected to the nozzle chamber 34 to allow fluid to flow. Note that the nozzle opening 24 is surrounded in the nozzle chamber 34 by a protruding rim 36 that "constrains" a meniscus (see FIG. 2) on the surface of the ink 40. Should be.

An ink inlet hole 42 (shown most clearly in FIG. 6) is formed in the floor 46 of the nozzle chamber 34. The hole 42 is formed to allow fluid to flow with the ink inlet channel 48 formed through the substrate 16.

The wall portion 50 protrudes from the hole 42 and extends upwardly from the floor portion 46. As described above, the skirt portion 32 of the nozzle 22 forms the first portion of the peripheral wall of the nozzle chamber 34 and the wall portion 50 forms the second portion of the peripheral wall of the nozzle chamber 34. do.

The wall 50 has an inwardly directed lip 52 at its free end, which acts as a fluid seal that prevents the escape of ink when the nozzle 22 is displaced, as described further below. It will be described in detail. Due to the viscosity of the ink 40 and the narrow gap between the lip 52 and the skirt portion 32, the inwardly directed lip 52 and surface tension prevent ink from escaping from the nozzle chamber 34. You'll understand the role of the seal.

The actuator 28 is a thermal bend actuator and is connected to the substrate 16 or, more specifically, to the anchor 54 extending upward from the CMOS passivation layer 20. The anchor 54 is secured to a conductive pad 56 electrically connected to the actuator 28.

The actuator 28 includes a first active beam 58 located above the second passive beam 60. In a preferred embodiment, both beams 58, 60 are or comprise a conductive ceramic material such as titanium nitride (TiN).

One end of both beams 58, 60 is fixed to the anchor 54 and the other end is connected to the arm 26. As current flows through the active beam 58, the beam 58 thermally expands. Since the passive beam 60 without current flow does not expand at the same rate, bending moments are generated in the arm 26, and as a result, as shown in FIG. It is displaced downward toward the substrate 16. Thereby, ink is ejected through the nozzle opening 24, as shown at 62 in FIG. When the heat source is removed from the active beam 58, i.e. by blocking the flow of current, the nozzle 22 is returned to a stationary state as shown in FIG. When the nozzle 22 is returned to the stopped state, the neck of the ink drop is broken as shown at 66 in FIG. 4 to form the ink drop 64. The ink drops 64 then travel to a print medium such as paper. As the ink droplets 64 are formed, “Negative” meniscus is formed as shown at 68 in FIG. 4. The “negative” meniscus 68 causes ink 40 to enter the nozzle chamber 34 and immediately forms a new meniscus for the next ink drop ejection from the nozzle assembly 10. Will be.

Hereinafter, the nozzle arrangement 14 will be described in detail with reference to FIGS. 5 and 6. The arrangement 14 is for four color printheads. Thus, the arrangement 14 includes four groups 70 for each color of the nozzle assembly. Each group 70 has nozzle assemblies 10 arranged in two rows 72, 74. One of the groups 70 is shown in detail in FIG. 6.

The nozzle assemblies 10 in one row 74 are inclined relative to the nozzle assemblies 10 in the other row 74 so that the nozzle assemblies 10 can be assembled in two rows 72, 74 to facilitate assembly. Staggered In addition, the nozzle assembly 10 of the one row 72 has a lever arm 26 of the nozzle assembly 10 of the other row 74 and the nozzle 22 of the nozzle assembly 10 of the one row 72. Are spaced far enough apart from one another to allow adjacent passage therebetween. Each nozzle assembly 10 is generally configured so that the nozzles 22 in one row 72 are sandwiched between the actuators 22 and the actuators 28 of adjacent nozzle assemblies 10 in the other row 74. ) Is shaped.

In addition, in order to facilitate the assembly of the nozzles 22 of the rows 72 and 74 in close contact, each nozzle 22 has a substantially hexagonal shape.

Those skilled in the art will appreciate that the nozzle passage 24 has a slight angle to the nozzle chamber 34 when the nozzle 22 is displaced toward the substrate 16 in use. It will be appreciated that the ink is ejected slightly away from the vertical direction. As shown in FIGS. 5 and 6, it is seen that the actuators 28 of the nozzle assemblies 10 of these rows 72, 74 are arranged in the same direction with respect to the sides of the rows 72, 74. It is an advantage of the invention. Therefore, the ink ejected from the nozzles 22 of the one row 72 and the ink ejected from the nozzles 22 of the other row 74 become parallel to each other to improve the printing quality.

In addition, as shown in FIG. 5, the substrate 16 has a coupling pad 76 on the substrate that electrically connects to the actuator 28 of the nozzle assembly 10 through the pad 56. Equipped. This electrical connection is made through a CMOS layer (not shown).

7 illustrates the invention in detail. In the context of the preceding figures, unless otherwise specified, like reference numerals refer to like parts.

The nozzle guard 80 is mounted on the substrate 16 of the arrangement 14. The nozzle guard 80 includes a body portion 82 having a plurality of passages 84 therethrough. The passageway 84 allows the nozzle assembly of the arrangement 14 to pass through the associated passageway 84 before the ink reaches the print medium when the ink is ejected from any one of the nozzle openings 24. Coincides with the nozzle opening 24 of FIG.

The body portion 82 is mounted at intervals with respect to the nozzle assembly 10 by limbs or struts 86. One of the struts 86 has an air inlet 88.

In use, ie when the arrangement 14 is activated, air is supplied through the air inlet 88 so that it can pass through the passage 84 with ink passing through the passage 84.

The ink is not suspended in the air because air is supplied through the passageway 84 at a different speed than the ink droplets 64, for example, the ink droplets 64 are weak from the nozzle 22. Ejected at a speed of 3 m / s. The air is supplied through the passageway 84 at a rate of about 1 m / s.

The purpose of the air supply is to prevent foreign matter from entering the passageway 84. Foreign particles, such as dust particles, fall into the nozzle assembly 10 and there is a risk of adversely affecting its operation. By forming the air inlet 88 in the nozzle guard 80 this problem can be significantly avoided.

Hereinafter, a manufacturing process of the nozzle assembly 10 will be described with reference to FIGS. 8 to 10.

First, a dielectric layer 18 is coated on the surface of the silicon substrate or wafer 16. The dielectric layer 18 is formed of about 1.5 micron CVD oxide. A resist is spin coated over the dielectric layer 18, and the layer is exposed to the mask 100 and then developed.

After being developed, the dielectric layer 18 is plasma etched downward toward the silicon layer 16. The resist is then removed and the layer is cleaned thoroughly. In this process, the ink inlet hole 42 is formed.

In FIG. 8B, about 0.8 micron aluminum 102 is applied to the dielectric layer 18. The resist is spin coated and the aluminum 102 is exposed to the mask 104 and developed. The aluminum 102 is plasma etched downward toward the dielectric layer 18, the resist is removed and the device is cleaned. In this process a bonding pad is provided and connected to the ink jet actuator 28. This connection causes the NMOS drive transistor and the power plane to be connected to each other on the CMOS layer (not shown).

About 0.5 micron PECVD nitride is coated with the CMOS passivation layer 20. The resist is spin coated and developed after the passivation layer 20 is exposed to the mask 106. After development, the nitride is plasma etched toward the silicon layer 16 in the region of the aluminum layer 102 and the inlet hole 42. The resist is removed and the device is cleaned.

A layer 108 of sacrificial material is spin coated on the passivation layer 20. The layer 108 is 6 micron photosensitive polyimide or about 4 μm high temperature resist. The layer 108 is softbaked and then exposed to a mask 110 and then developed. The layer 108 is then hardened at 400 ° C. for 1 hour when the layer 108 comprises polyimide, or at 300 ° C. or higher if the layer 108 is a high temperature resist. Hard bake. It should be noted in the drawings that deformation along the pattern of the polyimide layer 108 due to shrinkage should be considered in the design of the mask 110.

Next, as shown in FIG. 8E, a second sacrificial layer 112 is applied. The layer 112 is spin coated 2 μm photosensitive polyimide or a high temperature resist of about 1.3 μm. The layer 112 is softbaked and exposed with a mask 114. After exposure to the mask 114, the layer 112 is developed. When the layer 112 is polyimide, the layer 112 is hardbaked at 400 ° C. for about 1 hour. If the layer 112 is a resist, it is hardbaked for about 1 hour at a temperature higher than 300 ° C.

Next, a 0.2 micron multilayer metal layer 116 is coated. Part of the layer 116 forms the passive beam 60 of the actuator 28.

The layer 116 is formed by sputtering 1,000 nm of titanium nitride (TiN) at about 300 ° C. and sputtering 50 nm of tantalum nitride (TaN). 1,000 ns of TiN are further sputtered, and 50 ns of TaN and 1,000 ns of TiN are further sputtered.

Materials that can be used instead of TiN include TiB₂, MoSi₂, or (Ti, Al) N.

The layer 116 is then exposed to the mask 118, developed, and plasma etched down towards the layer 112, wherein the resist applied to the layer 116 is formed by the cured layer 108 or 112. Peel off in humid conditions, taking care not to remove.

The third sacrificial layer 120 is applied by spin coating 4 μm photosensitive polyimide or about 2.6 μm high temperature resist. The layer 120 is exposed to the mask 122 after softbaking. The exposed layer is then developed and hardbaked. In the case of polyimide, the layer 120 is hardbaked at 400 ° C. for about 1 hour, or at 300 ° C. or higher when the layer 120 contains resist.

A second multilayer metal layer 124 is applied to the layer 120. The composition of the layer 124 is the same as the layer 116 and is applied in the same way. Both layers 116 and 124 are electrically conductive layers.

The layer 124 is exposed with a mask 126 and then developed. After the layer 124 has been plasma etched down towards the polyimide or resist layer 120, the resist applied to the layer 124 is carefully moistened so that the cured layer 108, 112 or 120 is not removed. Peeled off The remainder of the layer 124 forms the active beam 58 of the actuator 28.

The fourth sacrificial layer 128 is applied by spin coating 4 μm photosensitive polyimide or about 2.6 μm high temperature resist. The layer 128 is softbaked, exposed to the mask 130 and then developed to leave Island Portions as shown in FIG. 9K. The remaining portion of layer 128 is hardbaked at about 400 ° C. for polyimide for about 1 hour and at least 300 ° C. for resist.

As shown in FIG. 8L, a dielectric layer 132 having a high Young's Modulus is coated. The layer 132 is made of silicon nitride or aluminum oxide of about 1 μm. The layer 132 is coated at a temperature lower than the hardbaking temperature of the sacrificial layers 108, 112, 120, and 128. The main properties required for this dielectric layer 132 are high modulus of elasticity, chemical inertness and good adhesion to TiN.

The fifth sacrificial layer 134 is applied by spin coating 2 μm photosensitive polyimide or about 1.3 μm high temperature resist. The layer 134 is softbaked, exposed to the mask 136 and developed. The remainder of the layer 134 is then hardbaked at 400 ° C. for about 1 hour in the case of polyimide and at 300 ° C. or higher in the case of resist.

The dielectric layer 132 is plasma etched downward toward the sacrificial layer 128 while being careful not to remove any portion of the sacrificial layer 134.

This step forms the opening 24, lever arm 26 and anchor 54 of the nozzle assembly 10.

Dielectric layer 138 having a high Young's modulus is coated. The dielectric layer 138 is formed by coating 0.2 탆 silicon nitride or aluminum oxide at a temperature lower than the temperature at which the sacrificial layers 108, 112, 120 and 128 are hard baked.

Next, as shown in FIG. 8P, the layer 138 is plasma etched anisotropically to a depth of 0.35 microns. This etching is intended to remove dielectric material from all surfaces except the sidewalls of the dielectric layer 132 and the sacrificial layer 134. This process forms the nozzle rim 36 "restricting" the meniscus of ink around the nozzle opening 24 as described above.

Ultraviolet (UV) emitting tape 140 is applied. A 4 μm resist is spin coated on the backside of the silicon wafer 16. The wafer 16 is exposed with a mask 142 to back etch the wafer 16 to form an ink inlet channel 48. The resist is then stripped from the wafer 16.

An additional ultraviolet emitting tape (not shown) is applied to the backside of the wafer 16 and the tape 140 is removed. As shown in FIGS. 8R and 9R, the sacrificial layers 108, 112, 120, 128 and 134 are stripped with oxygen plasma to provide the final nozzle assembly 10. For ease of reference, reference numerals shown in these two figures are the same as those shown in FIG. 1 to indicate the relevant parts of the nozzle assembly 10. 11 and 12 show the operation of the nozzle assembly 10 manufactured according to the manufacturing method described above with reference to FIGS. 8 and 9, which are consistent with FIGS. 2 to 4.

Those skilled in the art will appreciate that many variations and / or modifications as shown in the specific embodiments above are possible without departing from the spirit or scope of the invention as broadly described. Accordingly, the above embodiments are to be considered in all respects as illustrative and not restrictive.

Claims (13)

Substrate; A nozzle opening formed on the substrate, the nozzle opening being connected to the nozzle chamber, wherein at least one nozzle is required for the substrate to eject ink from the nozzle chamber to the nozzle opening if necessary. At least one nozzle adapted to be movable; And An actuator disposed outside the nozzle and connected to the nozzle for controlling the displacement of the nozzle; Ink jet printhead comprising a. The method of claim 1, The nozzle may include a crown portion forming an opening and a skirt portion connected to the crown portion and forming a first portion of the nozzle chamber peripheral wall. . The method of claim 2, And an ink inlet hole formed in the floor of the nozzle chamber and a protruding wall surrounding the hole and forming a second portion of the peripheral wall of the nozzle chamber. The method of claim 3, wherein And the skirt portion is movable relative to the substrate and the protruding wall serves as a prevention means for preventing ink from leaking from the nozzle chamber. The method of claim 1, The actuator is an ink jet printhead, characterized in that the thermal bend (Thermal Bend) actuator. The method of claim 5, And said thermal bend actuator is formed of two beams, an active beam and a passive beam. The method of claim 6, And the actuator is connected to the nozzle by a connecting member. The method of claim 7, wherein And the beams are fixed at one end to an anchor mounted on the substrate and at the opposite end to the connecting member. The method of claim 8, And the connecting member comprises an arm having one end connected to the actuator and a nozzle connected to the opposite end of the arm in a cantilevered form. The method of claim 1, And a plurality of nozzles disposed on the substrate and having respective actuators and connecting members. The method of claim 1, An ink jet printhead formed by planar monolithic deposition, lithographic, and etching processes. The method of claim 1, And the substrate comprises an integrated drive circuit layer layer. The method of claim 12, And the integrated driver circuit layer is molded through a CMOS fabrication process.