KR100438837B1 - Bubble-jet type ink-jet printhead - Google Patents

Abstract

A bubble jet ink jet print head and a heater thereof are disclosed. The disclosed bubble jet ink jet print head includes: a substrate in which a manifold for supplying ink, an ink chamber having a substantially hemispherical shape, and an ink channel for supplying ink from the manifold to the ink chamber are integrally formed; A nozzle plate stacked on the substrate and having a plurality of nozzles formed at a position corresponding to the center of the ink chamber; Rectangular heaters provided on the nozzle plate to face each other with the nozzles interposed therebetween; A rectangular metal conductor connecting one end of the heaters to the nozzle plate; And an electrode electrically connected to the heater on the nozzle plate to apply a current to the heater. According to this, the current density flowing through the inside of the heater is increased while the area of the heater is increased, so that the growth rate of the bubble can be increased, and the electrode connected to the heater facilitates the cooling of the heater to increase the driving frequency of the print head, thereby achieving high speed printing. To do it.

Description

Bubble-jet type ink jet printhead {Bubble-jet type ink-jet printhead}

The present invention relates to an ink jet print head.

In general, an ink jet print head is an apparatus for ejecting a small droplet of printing ink to a desired position on a recording sheet to print an image of a predetermined color. In the ink ejection method of such an ink jet printer, a bubble jet method, which is an electro-thermal transducer that generates bubbles in the ink by using a heat source and ejects ink with this force, and a piezoelectric body There is an electro-mechanical transducer which discharges ink by volume change of ink caused by deformation of the piezoelectric element.

FIG. 1 is a cross-sectional view briefly showing an ink ejecting portion of a back-shooting method disclosed in IEEE MEMS '98, pp. 57-62, as an example of a conventional bubble jet ink jet print head. Here, the back-shooting system refers to an ink ejecting method in which the bubble growth direction and the ink droplet ejecting direction are opposite.

As shown in FIG. 1, in the back-shooting printhead, a heater 30 is disposed around the nozzle 22 formed in the nozzle plate 20, which is not shown in the heater 30. An electrode for applying a current is connected. The nozzle plate 20 is coupled to the substrate 10, and the ink chamber 14 is formed in the substrate 10 corresponding to the nozzle 22. The ink chamber 14 is connected with the ink channel 16 and filled with ink 90 therein. In the ink discharge part having such a configuration, when a current is applied to the heater 30, bubbles 92 are generated in the ink chamber 14 filled with the ink 90 while the heater 30 is heated. Thereafter, the bubble 92 receives heat from the heater 30 and continuously expands. Accordingly, pressure is applied to the ink 90 filled in the ink chamber 14, so that the ink (near the nozzle 22) ( 90 is discharged to the outside through the nozzle 22 in the form of ink droplets 90 '. Then, the ink 90 is filled into the ink chamber 14 again while the ink 90 is sucked through the ink channel 16.

As the heater, a heater having a shape surrounding the nozzle has been proposed to generate a donut shaped bubble. As an example of such a heater, FIGS. 2 and 3 show ring and omega ( Heaters are shown.

First, referring to FIG. 2, an annular heater 31 surrounding the nozzle 22 is formed around the nozzle 22, and the heaters 31 have electrodes 41a and 41b for applying current. They are connected facing each other. That is, this heater 31 is a form connected in parallel between the both electrodes 41a and 41b. Therefore, the current flows through the heater 31 along two paths, a path passing through the X point and a path passing through the Y point. In this case, since the potential difference across the X and Y paths is the same, and the resistance values of the heaters 31 on both paths are the same, the amount of heat generated by the heater 31 on the X and Y paths is also theoretically the same. In detail, the thickness and width of the heater 31 on both paths and the length thereof are also the same, so that the resistance value R defined by the formula R = ρx (L / A) is the same, thereby forming a parallel circuit. The currents flowing along both paths become equal. Accordingly, the power consumption W defined by W = I x V x t is also the same, so that the amount of heat generated in proportion to the power consumption is the same in the heater 31 on both paths.

However, in practice, when forming the heater 31 on the nozzle plate, due to process variations, it is difficult to form the thickness or width of the heater 31 exactly the same on both paths. As such, when there is a deviation in the thickness or width of the heater 31 on both paths, the resistance value of the heater 31 is different from each other on both paths, and accordingly, the current flowing through both paths also changes. There is a difference in the amount of heat generated by the heater 31 on the path. The difference in the amount of heat generated by the location of the heater 31 causes non-uniform growth of bubbles, thereby causing a problem that ink droplets are not discharged in the correct direction, that is, the direction perpendicular to the nozzle plate.

Next, referring to FIG. 3, an omega heater 32 surrounding the nozzle 22 is formed around the nozzle 22. Electrodes 42a for applying a current to both ends of the heater 32 are provided. 42b) are respectively connected. That is, this heater 32 is a form connected in series between both electrodes 42a and 42b. Therefore, in the heater 32 of the type shown in FIG. 3, there are few problems with the heater 31 of the type shown in FIG. 2 described above.

However, in the omega heater 32, another problem occurs when the width thereof is made wider for ejection of larger ink droplets. That is, when the width of the heater 32 is increased by more than a certain limit, there is a problem that a significant difference occurs in the current density on the inner path indicated by the solid arrow and the outer path indicated by the dotted arrow. This problem may also occur in the heater 31 of the type shown in FIG. 2 described above. Explaining this in detail, although the cross-sectional area of the heaters 32 on both paths are the same, the length of the circumferential outer path with the larger diameter is much longer than the length of the circumferential inner path with the smaller diameter R. The resistance value R defined by = ρx (L / A) becomes larger on the outer path. This results in more current flowing along the inner path, resulting in more heat generated by the heater 32 on the inner path.

As the width of the heater 32 increases, the difference in the amount of heat generated on the inner path and the outer path increases. Accordingly, the bubble also occurs only on the inner path, and thus it is difficult to generate large bubbles as intended. . Therefore, in the omega-shaped heater 32, it is difficult to produce larger bubbles and eject larger ink droplets simply by widening the width thereof.

The present invention was created in order to solve the problems of the prior art as described above, and an object of the present invention is to expand the area of the heater but to make the current density uniform so that the bubble is increased and the size of the discharged droplet is increased. It is to provide an ink jet print head of the type.

Another object of the present invention is to provide a bubble jet ink jet print head in which two nozzles are arranged adjacent to each other to add droplets discharged from the two nozzles to increase the size of the droplets.

1 is a cross-sectional view of an ink ejecting portion showing an example of a conventional bubble jet ink jet print head,

2 is a plan view showing an example of a heater shape of an ink jet print head;

3 is a plan view showing another example of the heater shape of the ink jet print head,

4 is a schematic plan view of a bubble jet ink jet print head according to the present invention;

5 is an enlarged plan view of the ink ejecting unit according to the first embodiment of the present invention;

6 is a cross-sectional view showing a vertical structure of the ink ejecting portion shown in FIG. 5;

7 is a plan view showing a modification of the ink ejecting portion shown in FIG. 5;

FIG. 8 is a cross-sectional view showing a modification of the ink ejecting portion shown in FIG. 6;

9 is a plan view of an ink ejecting unit according to a second embodiment of the present invention;

10A and 10B are cross-sectional views illustrating a mechanism in which ink is ejected from the ink ejecting portion shown in FIG. 6;

11A and 11B are cross-sectional views illustrating a mechanism in which ink is ejected from the ink ejecting portion shown in FIG. 8;

12 is a plan view showing an ink ejecting unit according to a third embodiment of the present invention;

FIG. 13 is a schematic vertical sectional view of the ink ejecting portion shown in FIG. 12;

14 is a plan view showing an ink ejecting portion according to a modification of the third embodiment of the present invention;

<Explanation of symbols for the main parts of the drawings>

100, 200, 300, 300 '... ink discharge part 102: electrode pad

110,310 ... substrate 112,312 ... manifold

114,314 ... ink chamber 116,316 ... ink channel

120,320 ... Nozzle plate 122,322 ... Nozzle

130,230,330 ... heater 135,235,335 ... metal conductor

150,250,350 ... electrode 180 ... nozzle guide

In order to achieve the above object, a bubble jet ink jet print head of the present invention includes a manifold for supplying ink, an ink chamber having a substantially hemispherical shape and filled with ink to be ejected, and ink for the manifold. A substrate in which an ink channel for supplying the ink chamber from the substrate is integrally formed; A nozzle plate stacked on the substrate and having a plurality of nozzles configured to discharge ink at a position corresponding to the center of the ink chamber; Heaters provided on the nozzle plate to face each other with the nozzles interposed therebetween; A metal conductor connecting one end of the heaters to the nozzle plate; And an electrode provided on the nozzle plate so as to face the metal conductor from each heater and electrically connected to the heater to apply a current to the heater, wherein the heater has a substantially uniform current density. It is done.

A substrate having an integrally formed manifold for supplying ink, an ink chamber having a substantially hemispherical shape and filled with ink to be ejected, and an ink channel for supplying ink from the manifold to the ink chamber;

The bubble jet ink jet print head of the present invention comprises: a nozzle plate stacked on the substrate, the nozzle plate having a plurality of nozzles for ejecting ink at a position corresponding to the center of the ink chamber; A heater surrounding one side of each nozzle on the nozzle plate to be opened; And electrodes electrically connected to both ends of the heater on the nozzle plate to apply current to the heater.

In addition, the bubble jet ink jet print head of the present invention includes a manifold for supplying ink, an ink chamber having a substantially hemispherical shape and filled with ink to be ejected, and ink from the manifold to the ink chamber. A substrate in which ink channels to be supplied are integrally formed; A nozzle plate stacked on the substrate and having a plurality of nozzles configured to discharge ink at a position corresponding to the center of the ink chamber; Heaters provided on the nozzle plate to face each other with the nozzles interposed therebetween; And electrodes electrically connected to respective ends of heaters on both sides of each nozzle on the nozzle plate to apply a current to the heater, wherein the heaters are configured to have a substantially uniform current density. It may be.

In order to achieve the above object, the bubble jet ink jet print head of the present invention includes a manifold for supplying ink, two ink chambers having a substantially hemispherical shape and filled with ink to be ejected, and ink. A substrate in which ink channels for supplying from the manifold to the respective ink chambers are integrally formed; A nozzle plate stacked on the substrate and having a plurality of nozzles configured to discharge ink at a position corresponding to the center of the ink chamber; Heaters formed in a shape surrounding the nozzle on the nozzle plate and provided with a metal conductor at a connection portion thereof; And electrodes electrically connected to one end of the heaters facing the metal conductor on the nozzle plate to apply current to the heaters.

According to the present invention as described above, the nozzle area is increased to increase the nozzle area, and the width of the heater surrounding the nozzle increases the discharge of larger ink droplets and the generation of larger bubbles.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements, and the size of each element may be exaggerated for clarity and convenience of description. In addition, when one layer is described as being on top of a substrate or another layer, the layer may be present over and in direct contact with the substrate or another layer, with a third layer in between.

4 is a schematic plan view of a bubble jet ink jet print head according to a first embodiment of the present invention.

Referring to FIG. 4, in the print head according to the present invention, the ink ejecting portions 100 are arranged in a zigzag pattern on the ink supply manifold 112 indicated by a dotted line, and are electrically connected to the respective ink ejecting portions 100. Bonding pads 102 to which wires are to be bonded are disposed at both edges. Manifold 112 is connected with an ink container (not shown) containing ink. In addition, one manifold 112 may be formed for each column of the ink ejection unit 100. Although the ink ejection parts 100 are arranged in two rows in the drawing, they may be arranged in one row or may be arranged in three or more rows to further increase the resolution. Meanwhile, although a print head using only one color of ink is illustrated in the drawing, three or four groups of ink ejection units may be disposed for each color for color printing.

5 is an enlarged plan view of the ink ejecting unit according to the first embodiment of the present invention, and FIG. 6 is a cross-sectional view illustrating a vertical structure of the ink ejecting unit shown in FIG.

5 and 6 together, an ink chamber 114 in which ink is filled on a surface thereof is formed on a substrate 110 of the ink ejection part 100, and ink is supplied to the ink chamber 114 on an underside thereof. A supply manifold 112 is formed, and an ink channel 116 connecting the ink chamber 114 and the manifold 112 is formed at the bottom center of the ink chamber 114. The ink chamber 114 is preferably in a substantially hemispherical shape.

Here, the substrate 110 is preferably made of silicon widely used in the manufacture of integrated circuits. For example, a silicon substrate having a crystal direction of [100] and a thickness of approximately 500 μm may be used as the substrate 110. This is because silicon wafers widely used in the manufacture of semiconductor devices can be used as they are and are effective for mass production. In addition, the ink chamber 114 may be formed by isotropically etching the surface of the substrate 110 exposed through the nozzle 122 formed on the nozzle plate 120 to be described later, and the manifold 112 may be formed of the substrate 110. It may be formed by oblique etching or anisotropic etching the back surface of. At this time, the ink chamber 114 is formed to have an approximately hemispherical shape having a depth and a radius of approximately 20 mu m. On the other hand, the ink chamber 114 may be formed by isotropic etching after anisotropically etching the surface of the substrate 110 to a predetermined depth. In addition, the ink channel 116 may be formed by anisotropically etching the bottom center portion of the ink chamber 114 through the nozzle 122. At this time, the cross-sectional area of the ink channel 116 is formed to be equal to or slightly smaller than the cross-sectional area of the nozzle 122, which is a reverse flow phenomenon in which the ink is pushed toward the ink channel 116 during ink ejection, and its speed when refilling the ink after ink ejection. The cross sectional area needs to be finely controlled when the ink channel 116 is formed.

A nozzle plate 120 having a nozzle 122 is formed on a surface of the substrate 110 to form an upper wall of the ink chamber 114. When the substrate 110 is made of silicon, the nozzle plate 120 may be formed of a silicon oxide film formed by oxidizing the silicon substrate 110. Specifically, when the silicon wafer is placed in an oxidation furnace and wet or dry oxidation, an oxide film is formed on the surface of the silicon substrate 110 to form the nozzle plate 120.

The nozzle plate 120 has a long hole-shaped nozzle 122 formed in the transverse direction of the nozzle plate 120, and in the transverse direction of the nozzle plate 120 with the nozzle 122 interposed therebetween on the nozzle plate 120. A rectangular bubble generator 130 is formed to face each other. One end of the heaters 130 is interconnected by a metal conductor 135, and the other end is connected to the electrode 150, respectively.

On the other hand, the heater 130 is made of a resistive heating element such as polysilicon doped with impurities. Specifically, the doped polysilicon may be formed to a thickness of approximately 0.7 to 1 μm by low pressure chemical vapor deposition (LPCVD) by depositing with a source gas of phosphorus (P), for example, as an impurity. The deposition thickness of this polysilicon film may be set in another range so as to have an appropriate resistance value in consideration of the width and length of the heater 130. The polysilicon film deposited on the entire surface of the nozzle plate 120 is patterned into a rectangular shape by a photolithography process using a photomask and a photoresist and an etching process by etching the photoresist pattern as an etching mask.

A silicon nitride film may be formed on the nozzle plate 120 and the heater 130 as the insulating layer 140. Insulating layer 140 may be deposited by, for example, low pressure chemical vapor deposition to a thickness of approximately 0.5 μm.

A portion of the insulating layer 140 made of a silicon nitride film is etched to expose the heater 130 of the portion to be connected to the electrode 150. In order to apply a pulsed current, an electrode 150 made of a metal is usually formed by depositing and patterning a metal having good conductivity and easy patterning, such as aluminum or an aluminum alloy, by a sputtering method to a thickness of about 1 μm. In this case, the metal film forming the electrode 150 is simultaneously patterned to form a wiring (not shown) and a bonding pad (102 in FIG. 4) at other portions of the substrate 110.

Since the metal conductor 135 has a very small resistance and hardly has a potential difference between both ends thereof, almost no heat is generated in itself, and serves as a heat sink for dissipating heat during cooling of the heater 130. When the metal conductor 135 is formed of the same material as the electrode 150, the manufacturing process is simplified when performed with the process of forming the electrode 150.

A silicon oxide layer may be formed as the passivation layer 160 on the insulating layer 140 and the electrode 150. The silicon oxide film 160 may be deposited by a chemical vapor deposition method at a low temperature, for example, 400 ° C. or less, in a range in which the electrode 150 made of aluminum or an alloy thereof and the bonding pad are not deformed to a thickness of about 1 μm.

After the photoresist pattern is formed on the entire surface of the protective layer 160, the protective layer 160, the insulating layer 140, and the nozzle plate 120 are sequentially etched using the photoresist pattern as an etch mask. A long hole nozzle 122 having a length of ˜30 μm is formed. The ink chamber 114 and the ink channel 116 described above are formed through the nozzle 122 formed as described above.

Unlike the conventional circle, the nozzle 122 is close to an ellipse and preferably has a ratio of horizontal length L2 to vertical length L1 of about 1.1 to 1.5. Such a nozzle makes it possible to increase the nozzle area and increase the droplet size by increasing the length in the lateral direction.

The print head of the above structure can increase the size of the heater because the current density in the heater 130 is uniform, thereby increasing the size of the bubble generated.

On the other hand, since the electrodes 150 in the first embodiment are located on one side of the heaters 130, the electrode pads connected to the electrodes 150 in the ink print head having the ink ejecting portion 100 of this structure are provided. 4 (see 102 in Fig. 4) is preferably arranged on the side corresponding to the electrode 150. Therefore, in the structure of the print head in which the ink ejecting portions 100 are arranged in two rows as shown in FIG. 4, the opposing ink ejecting portions 200 are arranged in a zigzag symmetry, and the electrode 150 is an electrode of the nozzle plate 120. It is preferred to face outward towards the pad 102.

FIG. 7 is a plan view illustrating a modification of the ink ejecting unit according to the first embodiment of FIG. 5. Since the ink ejecting portion shown in FIG. 7 is mostly the same as that shown in FIG. 5, the same reference numerals as those in the first embodiment are used for the same components, and detailed description thereof will be omitted.

The ink ejecting part 100 ′ shown in FIG. 7 surrounds the nozzle 122 instead of the heaters 130 of FIG. 5 and the metal conductor 135 of FIG. 130 '). Both ends of the heater 130 'are connected in series to one electrode 150, respectively.

Unlike the conventional circle, the nozzle 122 is close to an ellipse and preferably has a ratio of horizontal length L2 to vertical length L1 of about 1.1 to 1.5. Such a nozzle makes it possible to increase the nozzle area and increase the droplet size by increasing the length in the lateral direction.

In this type of heater 130 ′, even if the width thereof is increased, the curved portion is small, so that the uniformity of the current density is maintained to some extent, and the amount of heat generated on the entire heater 230 is uniform. This means that as the width of the heater 130 ′ is increased, a large bubble corresponding thereto can be generated, and since the heaters are connected as one, the generated bubbles are easily merged into one.

FIG. 8 is a cross-sectional view showing a modification of the ink ejecting portion shown in FIG. 6. Since the ink ejecting portion shown in FIG. 8 is largely the same as that shown in FIG. 6, a brief description will be made focusing on the difference.

In the ink ejection portion 100 ″ shown in FIG. 8, the bottom surface of the ink chamber 114 is roughly spherical as in the above-described embodiment, but the ink chamber 114 ′ is formed from the edge of the nozzle 122 ′ at the top thereof. The nozzle guide 180 extending in the depth direction of the 114 is formed. The function of the nozzle guide 180 will be described later. Such a nozzle guide 180 may be simultaneously formed in the process of forming the ink chamber 114. Specifically, first anisotropically etching the substrate 110 of the portion exposed through the nozzle 122 ′ to form a groove having a predetermined depth, and then a predetermined material film such as TEOS (Tetraethyle ortho silane) on the inner surface of the groove. An oxide film is deposited to a thickness of approximately 1 mu m. Subsequently, when the TEOS oxide film formed on the bottom of the groove is etched and removed, the nozzle guide 180 made of the TEOS oxide film is formed on the inner circumferential surface of the groove. Next, when the substrate 110 exposed to the bottom of the groove is isotropically etched, an ink chamber 114 having a nozzle guide 180 may be formed on the substrate 110 as shown in FIG. 7.

9 is a plan view of the ink ejecting unit according to the second embodiment of the present invention.

Since the ink ejection unit 200 according to the present embodiment has most of the same components as the ink ejection unit of the above-described embodiment, and only the shape of the heater 230 and the connection form of the electrode 250 are different, it will be described with reference to this. do.

As shown, the heater 230 of the ink discharge unit 200 according to the present embodiment is formed in the nozzle plate 220, the nozzle 222 of the long hole shape in the transverse direction of the nozzle plate 220, the nozzle On the plate 220, a rectangular bubble generating heater 130 is formed to face each other in the transverse direction of the nozzle plate 120 with the nozzle 122 interposed therebetween. Both ends of the heaters 230 are connected to one electrode 150, respectively, and the heaters 230 are connected to the electrodes 150 in parallel.

Unlike the conventional circle, the nozzle 222 is close to an ellipse and preferably has a ratio of the horizontal length L2 to the vertical length L1 of about 1.1 to 1.5. Such a nozzle makes it possible to increase the nozzle area and increase the droplet size by increasing the length in the lateral direction.

The electrode 250 is very small in resistance and generates little heat by itself. In this type of heater 230, even if the width is larger, the uniformity of the current density is maintained, so that the amount of heat generated on the entire heater 230 is uniform. This means that as the width of the heater 230 is increased, a corresponding large bubble can be generated. In addition, since the heat dissipation proceeds smoothly in the electrode 250 when the heater 230 is cooled, it also serves as a heat sink.

On the other hand, since the electrode 350 in the second embodiment is located at both sides of the heater 230, an electrode pad connected to the electrode 250 in the ink print head having the ink ejecting portion 200 of this structure (Fig. 4, 102) is preferably arranged on both sides of the nozzle plate.

Hereinafter, the ink droplet ejection mechanism of the ink jet printhead according to the present invention having the above-described configuration will be described.

10A and 10B are cross-sectional views illustrating a mechanism in which ink is ejected from the ink ejecting portion shown in FIG. 6.

Referring first to FIG. 10A, ink 190 is supplied into the ink chamber 114 through the manifold 112 and the ink channel 116 by capillary action. In a state where the ink 190 is filled in the ink chamber 114, when a pulsed current is applied to the heater 130 through the electrode 150, heat is generated in the heater 130. The generated heat is transferred to the ink 190 through the nozzle plate 120 under the heater 130, whereby the ink 190 boils to generate bubbles 195. The shape of the bubble 195 becomes a substantially donut shape by the shape of the heater 130 surrounding the nozzle 122.

As the donut shaped bubble 195 expands over time, it expands under the nozzle 122 and expands into a concave, substantially disc shaped bubble 196 as shown in FIG. 9B. At the same time, ink droplet 191 is ejected from the ink chamber 114 through the nozzle 122 by the expanded bubble 196.

Blocking the applied current causes rapid cooling through the metal conductor (see 135 in FIG. 5), causing the bubble 196 to contract or otherwise burst before the ink 190 is replenished within the ink chamber 114. Is filled.

According to the ink ejection mechanism of the printhead according to the present invention as described above, the doughnut-shaped bubbles 195 are combined at the center to form a disk-shaped bubble 196 to cut the tail of the ejected ink droplets 191. No satellite droplets are formed. In addition, as the expansion of the bubbles 195 and 196 is limited to the inside of the hemispherical ink chamber 114, the back flow of the ink 190 is suppressed, so that cross talk with other adjacent ink ejecting portions is suppressed. Moreover, when the cross-sectional area of the ink channel 116 is smaller than the cross-sectional area of the nozzle 122, it is more effective for preventing the back flow of the ink 190.

In addition, since the shape of the ink chamber 114 is hemispherical, the expansion paths of the bubbles 195 and 196 are more stable than the conventional rectangular parallelepiped or pyramid ink chambers.

In particular, since the shape of the heater 130 is such that the current density in the inner portion and the outer portion thereof is uniform, even in the case of the heater 130 having a large width, the temperature of the inner portion and the outer portion is uniform and larger. The formation of bubbles and the ejection of larger ink droplets are made possible.

11A and 11B are cross-sectional views illustrating a mechanism in which ink is ejected from the ink ejecting portion shown in FIG. 8.

First, since the step shown in FIG. 11 is the same as the ink droplet ejection mechanism of the above-described embodiment, this will be briefly described. When the ink 190 is supplied and filled into the ink chamber 114, the electrode 150 is filled. The pulsed current is applied to the heater 130 through the ink, and the ink 190 boils due to the heat generated by the heater 130 to generate a substantially donut-shaped bubble 195 '.

The donut-shaped bubble 195 'expands over time. As the nozzle guide 180 is formed on the ink chamber 114 as shown in FIG. The probability of merging is small. However, the probability that this expanded bubble 196 'will merge under the nozzle 122 can be adjusted by adjusting the length extending downward of the nozzle guide 180. In particular, the droplet 191 discharged by the expanded bubble 196 ′ is guided by the nozzle guide 180 so that the droplet 191 may be discharged in a direction perpendicular to the substrate 110.

12 is a plan view of the ink ejecting portion according to the third embodiment of the present invention, and FIG. 13 is a cross-sectional view illustrating a schematic vertical structure of the ink ejecting portion shown in FIG.

12 and 13, two ink chambers 314 filled with ink are formed on a surface of the substrate 310 of the ink ejecting part 300, and the upper portions thereof communicate with each other. A manifold 312 is formed to supply ink to the ink chamber 314, and an ink channel 316 connecting the ink chamber 314 and the manifold 312 is formed at the bottom center of each ink chamber 314. Formed. The ink chamber 314 is preferably in a substantially hemispherical shape.

The nozzle plate 320 having the nozzle 322 is formed on the surface of the substrate 310 to form an upper wall of the ink chamber 314. The nozzle plate 320 is formed with two nozzles 322 spaced apart from each other, and separated from the nozzle 322 by a predetermined distance on the nozzle plate 320, so that the annular bubble generating heater 330 is overlapped. . In the overlapped portions of the heaters 330, a metal conductor 335 is formed to guide the heat dissipation and the current applied to the heater 330, and electrodes are formed at the other ends facing the overlapped portions of the heaters 330. It is connected to 350.

The metal conductor 335 and the electrode 350 are formed after exposing a part of the heater 330 in the insulating layer 340 covering the nozzle plate 320 and the heater 330, and the insulating layer ( The protective layer 360 is formed on the 340, the metal conductor 335, and the electrode 350.

The inkjet printhead structure as in the third embodiment has a form in which two printheads are connected in the lateral direction. The heater 330 is connected in parallel on the positive electrode 350, and current flows in the heater 330 along the X path and the Y path. In this case, the difference in the heat generation amount for each path may occur due to the deviation in the thickness or width of the heater 330, but the deviation is partially diluted in the metal conductor 335, which is the connection portion of the two heaters 330, two nozzles Two inks are ejected from 322 but these two droplets are combined on the printing paper to act as one droplet. Therefore, since the current density difference is twice the size of the droplets in the heater 330, which is kept equally lower than before, it contributes to the improvement of the printing speed. In addition, the metal conductor 335 contributes to the improvement of the driving frequency of the print head since the heat conduction acts upon cooling the print head.

14 is a plan view of the ink ejecting unit 300 'according to the modification of the third embodiment, and the same reference numerals are used for the same components as those of the third embodiment, and detailed description thereof will be omitted.

Referring to the drawings, two heaters 330 are arranged to be separated by a predetermined distance, and the two heaters 330 are electrically connected by the metal conductor 335.

The ink chamber 314 having such a structure is different in that the formation of the connection portion between the ink chambers 314 is different depending on the isolated distance of the heater 330, that is, the separation distance of the nozzle 322.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and equivalent other embodiments are possible. For example, the materials constituting each element of the print head of the present invention may be made of materials not illustrated. That is, the substrate may be replaced with another material having good processability even if it is not necessarily silicon. The same applies to a heater, an electrode, a silicon oxide film, and a nitride film. In addition, as a method of laminating and forming each material is merely illustrated, various deposition methods and etching methods may be applied.

As described above, the bubble jet inkjet printhead according to the present invention can increase the growth rate of bubbles by increasing the area of the heater and the uniform current density flowing therein, and the electrode connected to the heater By increasing the driving frequency of the print head to facilitate high-speed printing, it is possible to increase the nozzle size and increase the size of the droplets.

Claims (14)

A substrate having an integrally formed manifold for supplying ink, an ink chamber having a substantially hemispherical shape and filled with ink to be ejected, and an ink channel for supplying ink from the manifold to the ink chamber; A nozzle plate stacked on the substrate and having a plurality of nozzles configured to discharge ink at a position corresponding to the center of the ink chamber; Heaters provided on the nozzle plate to face each other with the nozzles interposed therebetween; A metal conductor connecting one end of the heaters to the nozzle plate; And And an electrode provided on the nozzle plate so as to face the metal conductor from the respective heaters and electrically connected to the heaters to apply a current to the heaters. The method of claim 1, The nozzle is in the shape of a long hole extending in one direction, And the heaters on both sides of the nozzle extend in the extending direction of the nozzle. The method of claim 2, Bubble nozzle type ink jet print head, characterized in that the aspect ratio of the nozzle is 1.1 to 1.5. The method of claim 1, And the metal conductor is connected vertically to the heater. A substrate having an integrally formed manifold for supplying ink, an ink chamber having a substantially hemispherical shape and filled with ink to be ejected, and an ink channel for supplying ink from the manifold to the ink chamber; A nozzle plate stacked on the substrate and having a plurality of nozzles having a long hole shape extending in one direction in which ink is discharged at a position corresponding to the center of the ink chamber; A heater surrounding one side of each nozzle on the nozzle plate to be opened; And a plurality of electrodes electrically connected to the other side of the heater on the nozzle plate to apply a current to the heater. delete The method of claim 5, wherein Bubble nozzle type ink jet print head, characterized in that the aspect ratio of the nozzle is 1.1 to 1.5. A substrate having an integrally formed manifold for supplying ink, an ink chamber having a substantially hemispherical shape and filled with ink to be ejected, and an ink channel for supplying ink from the manifold to the ink chamber; A nozzle plate stacked on the substrate and having a plurality of nozzles configured to discharge ink at a position corresponding to the center of the ink chamber; Heaters provided on the nozzle plate to face each other with the nozzles interposed therebetween; And And a plurality of electrodes electrically connected to respective ends of the heaters on both sides of the nozzles on the nozzle plate to apply current to the heaters. The method of claim 8, The nozzle is in the shape of a long hole extending in one direction, And the heaters on both sides of the nozzle extend in the extending direction of the nozzle. The method of claim 9, Bubble nozzle type ink jet print head, characterized in that the aspect ratio of the nozzle is 1.1 to 1.5. The method of claim 8, And the electrodes are vertically connected to the heater. A substrate integrally formed with a manifold for supplying ink, two ink chambers having a substantially hemispherical shape and filled with ink to be discharged, and an ink channel for supplying ink from the manifold to the respective ink chambers; A nozzle plate stacked on the substrate and having a plurality of nozzles configured to discharge ink at a position corresponding to the center of the ink chamber; Heaters formed in a shape surrounding the nozzle on the nozzle plate and provided with a metal conductor at a connection portion thereof; And And an electrode electrically connected to one end of the heaters facing the metal conductor on the nozzle plate to apply current to the heaters. The method of claim 12, The bubble jet ink jet print head of claim 1, wherein the two heaters connected to the metal conductor are integrally in contact with each other. The method of claim 12, Bubble heater type ink jet print head, characterized in that the two heaters connected to the metal conductor is isolated.