JP4446337B2 - Ink jet head, head cartridge, and ink jet recording apparatus - Google Patents

Description

  The present invention relates to an ink jet head, a head cartridge, and an ink jet recording apparatus, and more particularly to an ink jet head used to eject recording ink in the field of ink jet recording.

  Various recording methods have been developed as current image forming apparatuses. In particular, the inkjet recording method is non-contact with the recording medium, enables high-density recording, can be easily colored, can be downsized, and can be used for printing. Is widely used because it can be formed on demand without the need for

  In this ink jet recording apparatus, a so-called hot melt ink type ink jet recording apparatus that heats and changes from an individual to an ink liquid and jets is known as one of measures for preventing bleeding on a recording medium such as plain paper. However, many ink jet recording apparatuses using relatively high-viscosity inks that are fast to be fixed on a recording medium even if they are not phase-converted have been commercially available.

In addition, the ink jet technology is applied not only to image formation on paper media but also to the manufacturing process field as a method for applying a functional ink liquid because of the advantages described above. For example, it is actually used for the production of color filters for liquid crystal displays. Has been. In the future, by increasing the size of ejected droplets using inkjet technology, functional inks can be applied to media that are difficult to handle with conventional coating methods, such as large-area substrates for FPD and solid objects such as MEMS, and flexible. Application to on-demand drawing of electronic circuits on a substrate is expected to progress. In this case , not only ink having a viscosity of 20 mPa · s or less as used in general-purpose inkjet recording apparatuses currently on the market, but also a functional ink liquid having a viscosity higher than that at room temperature may be ejected.

On the other hand, high density of ink jet nozzles or miniaturization of ink droplets have been continuously promoted. As a result, since the ink flow path diameter including the nozzles is reduced, if the ink flow path resistance increases in inverse proportion to the fourth power of the ink flow path diameter, a larger force is required for ejection, and high frequency driving or multi-channel driving is required. Sometimes the supply of ink cannot catch up, the position of the meniscus at the nozzle changes, and the ejection characteristics change greatly. In particular, the tendency becomes more remarkable in the case of ink having a high viscosity.

Further, the ink of high viscosity is often the viscosity by temperature is greatly changed, the injection characteristic is very dependent on the viscosity, the temperature unevenness in the inkjet head and ejecting variation is very large ing large. Since the injection characteristics by liquid temperature changes significantly, the flow path, ing particularly required uniform liquid temperature control of the head.

  Therefore, many ink jet recording apparatuses have been proposed in which an ink supply system is provided with a heater for heating ink. As one of them, for example, in Patent Document 1, a heater is disposed in an ink supply path from an ink tank to an inkjet head, or in a common liquid chamber of the inkjet head, and ink is supplied in accordance with the ink ejection amount / ink flow rate in the inkjet head. And a method of ejecting ink with a low viscosity by heating the ink. Further, in the configuration for effectively raising the temperature of the ink flow path of the head, for example, Patent Document 2, a metal having high thermal conductivity is used for the ink flow path member, and further, the thermal conductivity is used for the support member of the flow path member. There has been proposed a method of efficiently heating the ink and the flow path member using a separately formed heater using a small resin member. Further, for example, in Patent Document 3, a heating element is used as an ejection unit, and as a countermeasure against temperature variation due to variation in the ejection amount between nozzles, the heating element is driven to the extent that ejection is not performed even during non-ejection. A method for uniformly holding the ink flow path has been proposed.

In addition, in order to suppress clogging of nozzles and ink flow paths due to dust in the ink, there are many ink jet printers equipped with a filter to filter the dust in the liquid in the ink supply path, but the diameter of the flow path is reduced. Accordingly, since the size of the dust to be filtered is reduced, it is essential to provide a filter having a small pore diameter. Therefore, Patent Document 4 proposes a configuration in which the temperature of the filter itself provided in the ink cartridge is increased for the purpose of reducing the fluid resistance in the filter unit and effectively increasing the temperature of the ink.
JP 2003-136758 A Japanese Patent Laid-Open No. 5-220952 JP 2001-113845 A JP-A-8-156280

However, when an image is formed, the ink ejection amount is different for each ink flow path of a plurality of individual nozzles arranged. When the heater is disposed only in the common flow path of the ink jet recording apparatus as in Patent Document 1, or when the ink flow path is heated by driving the heating element during non-ejection as in Patent Document 3, If not uniformly heat the entire ink jet head, a temperature difference occurs in the ink flow path and a small ink channel of the nozzle on busy injection quantity nozzle. In particular, when an ink liquid having a large viscosity change with respect to temperature is ejected, the ejection variation for each nozzle becomes large. Further, the recording duty (injection amount per unit time) for each nozzle or for the entire ejection head varies greatly depending on the recorded image. Therefore, in order to keep the liquid temperature in the ink flow path at a certain level or more, it is preferable to arrange a heater in the entire ink flow path as in Patent Document 1 described above, but with respect to the ink liquid volume in the ink flow path, If the ratio of the liquid contact area of the temperature raising member is not large, the liquid temperature unevenness in the ink flow path becomes large. In addition, since it takes time to raise the temperature, there are problems that it becomes difficult to perform high-speed recording by increasing the amount of injection, and the warm-up time at startup is increased.

  Moreover, when using a heater and a high heat conductive member like the said patent document 2, since a heat conductive member and a heat generating member become separate, a head structure becomes complicated. Also, since the thermal conductivity is too high, it is easily affected by the temperature of the external environment, and it becomes difficult to keep the entire head within a certain temperature range.

  Furthermore, when heating is performed by incorporating a heater on a substrate in which a pressure generating element is incorporated, it is necessary to heat the entire substrate to a relatively high temperature in order to heat the entire ink in the ink flow path above a certain temperature. There is a possibility that the pressure generating element or the control circuit for driving the pressure generating element may malfunction, and heat transfer from the substrate to a member other than the ink increases, so that it cannot be heated effectively.

Moreover, in the method of heating a filter like the said patent document 4, when passing a filter with a large surface area, a liquid temperature can be raised comparatively uniformly effectively. However, because it is provided in the ink cartridge, it is less or the injection amount of the entire injection head, the liquid temperature in the ink flow path from the filter to the inkjet head intends want reduced.

  The present invention is for solving these problems, and it is possible to keep a plurality of individual nozzles and the ink liquid in the ink flow path at a uniform temperature with a simple configuration, and in the ink flow path. Ink jet head, head cartridge, and ink jet recording apparatus capable of uniformly controlling the liquid temperature of the filter function part and further reducing the fluid resistance of the filter function part without reducing the filtering ability of impurities such as dust in the filter function part The purpose is to provide.

In order to solve the above problems, the ink jet head of the present invention is a plurality of nozzles for ejecting the ink liquid droplets, a plurality of individual liquid chambers ink liquid is retained which corresponds to each nozzle And partition walls constituting the individual liquid chambers, and pressure generating means for generating pressure in the ink liquid in the individual liquid chambers. Furthermore, according to the ink jet head of the present invention, the base material to be the partition is formed of a metal member having an electrical insulating film formed on the surface in contact with the ink liquid, and the partition is energized to increase the temperature. Heat the ink liquid. Therefore, it is possible to uniformly heat the ink liquids in the plurality of liquid chambers with a simple configuration, and as a result, it is possible to provide an ink jet head with small ejection variation.

  In addition, by energizing the partition walls between adjacent individual liquid chambers to generate heat, the entire ink liquid in the liquid chambers can be heated uniformly and efficiently, and the current path length / electric resistance can be increased even if the inkjet head is downsized. Since the heater can be controlled by a stable general-purpose power source, temperature controllability can be improved.

Further, by the septum wall between individual separate liquid chamber forms a single current path of which all consist of a single member she can be energized a constant current equal to the entire partition wall.

  In addition, since a plurality of individual liquid chambers are arranged and at least one dummy liquid chamber and nozzles that are not used for recording are formed at both ends, the temperature of the ink liquid between the liquid chambers used for recording The difference can be reduced, and an ink jet head with smaller ejection variation can be provided.

  Furthermore, a head cartridge as another invention is characterized by having the above-described ink jet head and an ink liquid container for storing ink liquid to be supplied to the ink jet head. Therefore, it is possible to prevent the liquid container from being attached to the incompatible liquid due to misuse by the user.

  According to another aspect of the invention, an ink jet recording apparatus includes the above-described ink jet head or the head cartridge, and a moving unit that relatively moves a recording medium to which ink liquid ejected from the ink jet head is attached. There is a feature. Accordingly, it is easy to maintain the liquid temperature from the ink tank to the nozzles of the ink jet head, and an ink jet recording apparatus with small ejection variation can be provided. In addition, even when using high-viscosity liquids, stable image recording is possible, and the temperature of the liquid in the common liquid chamber of the inkjet head can be increased quickly, thus shortening the warm-up time and reducing the time required for the entire recording. Can do.

According to the ink jet head of the present invention, it is possible to uniformly heat ink liquids in a plurality of liquid chambers, the ejection variation is small, the head configuration is simple, and the manufacturing cost of the ink jet head can be suppressed. .

  FIG. 1 is a diagram showing a configuration of an ink jet head according to a first embodiment of the present invention. 1A is a plan view, FIG. 2B is a cross-sectional view taken along the line AA ′ in FIG. 1A, and FIG. 2C is a cross-sectional view taken along line B- in FIG. It is B 'sectional view. FIG. 2 is an exploded plan view of the ink jet head according to the present embodiment.

  First, as shown in FIG. 2, the inkjet head 1 of the present embodiment includes a nozzle plate 10, a partition member 20, and a substrate 30. As shown in FIGS. 1 and 2, the nozzle plate 10 is formed with a liquid repellent film 11 for the ink liquid to be ejected and a nozzle 12 for ejecting the ink liquid as droplets. This nozzle plate 10 uses a polyimide film having a thickness of 30 μm as a base material, and a plurality of nozzles 12 are formed by laser processing or the like. Further, as shown in FIGS. 1B and 1C, individual liquid chambers 21 holding ink liquid are connected to the nozzles 12 respectively. Further, the plurality of individual liquid chambers 21 are connected to a common liquid chamber 23 and a supply port 24 so that ink liquid ejected from a tank (not shown) is supplied. As shown in FIG. 1, each individual liquid chamber 21 having a width of 50 μm and a length of 500 μm is divided by a partition wall 22b having a width of 20 μm. A partition wall 22a having a width of 1 mm is formed. The partition member 20 constituting the partition walls 22a and 22b is made of a stainless steel foil (SUS316) having a thickness of 50 μm (liquid chamber height and partition wall height), and includes wet etching, laser processing, electroforming (electroforming), and the like. The desired partition shape is formed by the method. Further, as shown in FIG. 2C, a pressure generating means 31 corresponding to each nozzle 12 and the individual liquid chamber 21 is formed on the substrate 30 serving as the bottom surface of the individual liquid chamber 21, and based on the image information. The pressure can be output at an arbitrary timing by a control means not shown.

  Further, as shown in FIGS. 1A and 2B, a power source 40 is connected to the end of the partition wall 22 a of the outer wall portion of the inkjet head 1. The partition wall 22a and the partition wall 22b between the adjacent individual liquid chambers 21 form a single current path from a single member so that a constant equal current can be applied to the entire partition wall. The temperature of the partition walls 22a and 22b is monitored by a temperature sensor not shown, and the energization time is controlled as shown in FIG. 3 (a), or the voltage (or current) amplitude is controlled as shown in FIG. 3 (b). The temperature is adjusted by controlling the number of energizations as shown in FIG. If it is not desirable to continue applying an electric field in a certain direction to the ejected ink liquid, such as when an electrochemical reaction occurs on the surface of the partition wall or the contents in the ink liquid are deposited, (d in FIG. The voltage polarity is alternately changed as shown in FIG. Stainless steel generally has a resistivity several tens of times higher than that of aluminum or copper (50-100E-6 Ωcm) used as a wiring material, and easily generates Joule heat simply by energization.

  Therefore, in the configuration of the first embodiment, the stainless steel partition wall 22b is meandered to form the individual liquid chamber 21, and the thin partition wall between the adjacent individual liquid chambers 21 is also used as a current path. Even so, it is possible to increase the resistance. As a result, since it becomes possible to stably energize using a general-purpose power source having a relatively large voltage, temperature control becomes easy. Further, since the entire partition occupying the two surfaces of the wall surface constituting the individual liquid chamber 21 generates heat, the heater contact area with respect to the ink liquid volume in the individual liquid chamber 21 is increased, and the individual liquid chamber 21 is effectively and uniformly disposed. Heat the ink. In particular, when the individual liquid chambers 21 are arranged at high density and the partition wall thickness is shorter than the partition wall height, for example, in the above-described embodiment, the partition wall thickness is 20 μm and the partition wall height is 50 μm, The ratio of the area in contact with other than the ink liquid in the individual liquid chamber 21 can be reduced with respect to the entire surface area. As a result, heat transfer from the partition wall 22 to the nozzle plate 10 and the substrate 30 and heat radiation from the outside to the outside are suppressed, so that ink temperature unevenness between the plurality of individual liquid chambers 21 in the head is reduced. Also in the heat transfer to the substrate 30, since the partition wall covers the entire inkjet head, the entire ejection head can be heated uniformly. In addition, since the partition wall that is originally required as an ink jet head can be used as a heater as it is, the head area can be reduced.

  By the way, a dummy liquid chamber 25 is formed at least at the outermost part of the plurality of individual liquid chambers 21 arranged as shown in FIGS. Since the width of the partition wall 22a is preferably wide in terms of strength of the inkjet head 1, the amount of heat generated is smaller than that of the partition wall between the individual liquid chambers 21 inside. As a result, the temperature of the ink liquid in the outermost liquid chamber 24 becomes lower than the inside, and uniform ejection becomes difficult. Therefore, a dummy liquid chamber 25 that is not used for actual recording is formed, and the ink liquid in the dummy liquid chamber 25 is discharged from the dummy nozzle 13 only when the ink liquid in the head is refreshed.

  In FIGS. 1 and 2, both the partition walls 22a and 22b are energized. However, as shown in FIG. 4, it is also possible to energize and heat only the partition walls 22b arranged inside the inkjet head. In the first embodiment, SUS316 having relatively good corrosion resistance is used as the base material of the partition walls 22a and 22b. However, martensite may be used as long as it has good corrosion resistance against the ink liquid to be ejected. Stainless steel of any of the followings: austenitic, austenitic, ferritic, two-phase, and precipitation hardened. If heat resistance is necessary in the manufacturing process of the ink jet head, a high heat resistant material such as Inconel, Incoloy, or Halostay may be used. Further, not only stainless steel but also a metal having a relatively high resistance such as titanium or nickel, or a semiconductor substrate such as silicon whose resistivity is adjusted by doping can be used.

  Further, even when there is a risk of corrosion due to the ink liquid to be ejected or the combination of the partition members, and even when the conductivity of the ejected ink liquid is high, the entire surface of the partition wall or the liquid contact surface is protected as shown in FIG. This can be dealt with by forming an oxide film to be the film 26 or separately forming an inorganic or organic corrosion-resistant film or insulating film.

  Furthermore, although the polyimide film is used as a member of the nozzle plate 10 shown in FIGS. 1 and 2, a metal plate such as nickel may be used. The pressure generating means includes a piezoelectric element that is an electromechanical conversion element currently used in general-purpose inkjet printers, a bubble element that generates bubbles by film boiling, or a minute gap as shown in FIG. An electrostatic actuator element that applies an electric field between the movable plate 33 and the individual electrode 34 facing each other via 32 and deforms the movable plate 33 with an electrostatic force can be applied regardless of the pressure generation type.

  However, in the case where a conductive member such as a metal member or a silicon wafer is used for the nozzle plate 10 or the substrate 30, when the partition member 20 which is an electrothermal conversion member is bonded, at least (a), (b), It is necessary to interpose the insulating member 27 as shown in (c). The insulating member 27 may be formed on the surface of the partition member as shown in FIG. 7 (a), or may be formed on the nozzle plate 10 or the substrate 30 side as shown in FIG. 7 (b). The insulating adhesive between the nozzle plate 10 and the substrate 30 may function as the insulating member 27 as shown in (c). In particular, when temperature control is performed by ON / OFF of a fine pulse voltage as shown in FIG. 3C, a member (material, thickness) that reduces the coupling capacity is provided at the joint. It is preferable to interpose.

  Further, in the combination in which the partition member 20 and the nozzle plate 10 or the substrate 30 have greatly different thermal expansion coefficients, the ejection head may be distorted or damaged in the worst case due to thermal stress. In that case, as shown in FIG. 8, a method of bonding using an adhesive such as an epoxy resin having a low Young's modulus to function as the thermal stress buffer material 28 is also suitable.

  Next, an ink jet head according to a second embodiment of the present invention will be described with reference to FIG. 9 showing the structure of the ink jet head. 1A is a plan view, FIG. 1B is a cross-sectional view taken along the line EE ′ of FIG. 1A, and FIG. 2C is a cross-sectional view taken along line F- of FIG. It is F 'sectional view taken on the line. In the first embodiment, both the partition walls 22a and 22b are energized in order to increase the resistance value. However, in the long inkjet head 2 in which the arrangement width of the nozzles 12 is large as in the second embodiment. Can be configured such that the outer peripheral partition walls 22a of the plurality of individual liquid chamber 21 rows generate heat by energization, and the partition walls 22b between the adjacent individual liquid chambers 21 are heated by heat transfer. In the second embodiment shown in FIG. 9, heat transfer to the partition wall 22b is performed mainly from the connection portion with the partition wall 22a on the nozzle 12 side. In the arrangement direction of the plurality of nozzles 12 or the individual liquid chambers 21, the amount of heat generated per unit length of the partition walls 22a is substantially equal, and heat can be uniformly transferred to the plurality of partition walls 22b.

  As shown in FIG. 10, the current may flow in a direction orthogonal to the arrangement of the plurality of nozzles 12 and the individual liquid chambers 21 of the inkjet head. In order to further facilitate heat transfer to the partition wall 22b, an ink liquid supply port 29 to the individual liquid chamber 21 is formed in the individual liquid chamber 21 as shown in FIG. 11, and the ink liquid supply port 29 on the nozzle 12 side is formed. It is also possible to transfer heat from the connecting portion with both the partition walls 22a. Furthermore, as shown in FIG. 12, there is no problem even with an inkjet head having a plurality of nozzles 12 and individual liquid chambers 21 rows. Further, in each example of the ink jet head shown in FIGS. 9 to 12, the so-called face shooter type ink jet head in which the nozzle 12 is formed on the surface of the nozzle plate 10 has been described. However, as shown in FIG. The present invention can also be applied to an edge shooter type ink jet head formed on a single side portion of the ink jet head.

  FIG. 14 is an exploded perspective view showing a schematic configuration of an ink jet head according to the third embodiment of the present invention. FIG. 15 is a plan view. In both figures, the same reference numerals as those in FIGS. 1 and 2 indicate the same components. The inkjet head 3 of the third embodiment shown in both figures includes a nozzle plate 10, a partition member 20, and a substrate 30. In the nozzle plate 10, a plurality of nozzles 12 for ejecting micro droplets are arranged, and the nozzles 12 are connected to the individual liquid chambers 21 divided by the partition member 20. The individual liquid chamber 21 is provided with a heat generating element 35 as pressure generating means, and is connected to the common liquid chamber 23 via a fluid resistance 36. A driver 37 for driving the heating element 35 at an arbitrary timing and a membrane 38 that is one of the wall surfaces of the common liquid chamber 23 are also formed on the silicon substrate 30 on which the heating element 35 is formed. A large number of micro holes 41 are formed on the membrane 38 for supplying ink liquid to the common liquid chamber 23 from a connection port 39 for connection to an external ink tank and for filtering impurities and dust in the ink liquid. Has been. Similarly, a heater 42 for raising the temperature of the ink liquid supplied to the inkjet head 3 is also formed so as to cover the entire surface of the membrane 38, and is disposed so as to pass between the plurality of micro holes 41. Yes.

  16 is a cross-sectional view taken along line P-P ′ of FIG. In the figure, an interlayer insulating film 44 made of a field oxide film 43 and a BPSG film and an interlayer insulating film 45 made of silicon nitride are stacked on a silicon substrate 30. A resistance layer 46 of tantalum nitride serving as the heating element 35 and the heater 42 is partially formed on the surface of the interlayer insulating film 45, and the surface of the resistance layer 46 is made of an aluminum alloy for energizing the resistance layer 46. A wiring layer 47 is formed. A protective film 48 made of silicon nitride is formed on the surfaces of the wiring layer 47, the resistance layer 46, and the interlayer insulating film 45, and a portion corresponding to the resistance layer 46 on the surface of the protective film 48 and its surroundings are heated by the resistance layer 46. An anti-cavitation film 49 is formed to protect the protective film 48 from chemical and physical impacts accompanying the above.

  14 and FIG. 15 corresponds to the heat application portion 50 that is a region where the wiring layer 47 on the surface of the resistance layer 46 is not formed. The membrane 38 is composed of a member sandwiching the interlayer insulating film 45 and the protective film 48 made of silicon nitride for the resistance layer 46, and a large number of micro holes 41 are formed in parallel with the heater 42. The wiring layer 47 is connected to a driver 37 for controlling energization to the heat acting part 50 that is the heat generating element 35. The driver 37 is formed on a P-type silicon substrate 30 using a general MOS process, and includes a PMOS transistor 51 and an NMOS transistor 52 that constitute CMOS logic, and an NMOS transistor 53 that drives the heating element 35. Etc. Further, the surface layer of the N-type well region 54 or the P-type well region 55 is deposited via a source region 56 and a drain region 57 into which P-type or N-type impurities are partially introduced, and a gate insulating film 58. The gate wiring 59 and the like are formed, and the PMOS transistor 51 or the NMOS transistors 52 and 53 are configured. Each element such as between the PMOS transistor 51 and the NMOS transistor 52 and between the NMOS transistor 52 and the NMOS transistor 53 is separated by an oxide film isolation region 60 formed by field oxidation. Further, each transistor is provided with an electrode 61 made of an aluminum alloy through the interlayer insulating film 43, and is connected between the transistors or connected to the wiring layer 47 through a contact hole formed in the interlayer insulating film 43. Yes.

  In the ink jet head 3 of the third embodiment having such a configuration, the driver circuit for driving the heater 42 is also formed in the driver 37 in the silicon substrate 30 at the same time as the heating element 35. The heater 42 is heated by arbitrarily controlling energization by a known control method such as ON / OFF control or PID control.

17 to 27 are process cross-sectional views illustrating the outline of the manufacturing process of the inkjet head of the present invention. Note that the driver formation step is omitted.
First, as shown in FIG. 17, the above-described driver circuit 71 is formed on a silicon substrate 70 having a crystal orientation (100). Then, as shown in FIG. 18, on the silicon substrate 70 on which the driver circuit 71 is formed, a silicon nitride film that becomes the interlayer insulating film 72 is formed by plasma CVD to a thickness of about 0.5 to 2 μm. Next, as shown in FIG. 19, a tantalum nitride film to be the resistance layer 73 is formed by sputtering to a thickness of about 0.1 to 0.5 μm and patterned by a well-known photolithography process. Then, as shown in FIG. 20, after an aluminum alloy film as the wiring layer 74 is formed by sputtering to a thickness of about 0.2 to 1 μm, it is similarly patterned by a well-known photolithography process. Next, as shown in FIG. 21, a silicon nitride film to be the protective film 75 is again formed by plasma CVD to a thickness of about 0.5 to 2 μm. Then, as shown in FIG. 22, the interlayer insulating film 72 and the protective film 75 made of a silicon nitride film are partially etched by ICP dry etching so that the minimum opening width for forming the microhole 76 is about 0.3 to 30 μm. The minute groove is formed. Next, as shown in FIG. 23, the silicon substrate 70 is etched from the back surface by ICP dry etching to form a connection port 77. Then, as shown in FIG. 24, the field oxide film 78 and the interlayer insulating film 79 made of BPSG are removed with a hydrogen fluoride aqueous solution, and the minute holes 76 are penetrated. Next, as shown in FIG. 25, a metal tantalum film that becomes the anti-cavitation film 80 is formed on the surface of the protective film 75 to a thickness of about 0.1 to 1 μm. Subsequently, as shown in FIG. 26, a negative photosensitive epoxy resin to be the partition member 81 is dropped on the silicon substrate 70 and applied by spin coating to a thickness of about 40 to 60 μm. After pre-baking, exposure and removal are performed by a photolithography process to form the individual liquid chamber 82, the fluid resistance 83, and the common liquid chamber 84. Finally, as shown in FIG. 27, a nozzle 86 having a thickness of about 10 to 30 μm is formed by laser processing on a stainless steel foil (SUS316) having a thickness of 25 μm to become the nozzle plate 85, and the surface of the nozzle surface is not shown very thin. A water repellent layer is formed and bonded onto the partition wall member 81.

  24, the field oxide film 78 and the interlayer insulating film 79 of the membrane are removed. However, the field oxide film 78 and the interlayer insulating film are formed by the manufacturing process shown in FIGS. 28 to 30 described below. It is also possible to leave 79.

28 to 30 are process cross-sectional views showing an outline of another production process of the ink jet head of the present invention. Note that the driver formation step is omitted, and this manufacturing step is the same as the manufacturing step shown in FIGS. 28 to 30, the same reference numerals as those in FIGS. 17 to 21 denote the same components.

  In FIG. 21, after a silicon nitride film to be a protective film 75 is formed by plasma CVD to a thickness of about 0.5 to 2 μm, a metal tantalum film to be a cavitation resistant film 80 is formed on the surface of the protective film 75 as shown in FIG. About 0.1 to 1 μm. Next, as shown in FIG. 29, the interlayer insulating film 72 and the protective film 75, and the field oxide film 78 and the interlayer insulating film 79 are partially etched by dry etching, so that the minimum opening width for forming the microhole 76 is reduced. A minute groove of 0.5 μm or more is formed. Then, as shown in FIG. 30, the silicon substrate 70 is etched from the back surface by ICP dry etching to form the connection port 77 and the membrane 87, and the minute hole 76 is penetrated.

  In the manufacturing process shown in FIGS. 17 to 27 and the manufacturing process shown in FIGS. 28 to 30 described above, the back surface etching of the silicon substrate 70 is performed by ICP dry etching, but TMAH (tetramethylammonium hydride) is used. It can also be formed by anisotropic wet etching using

  In the configuration and manufacturing process of the ink jet head of the present invention described above, the membrane including the heater is formed in a series of film forming steps for forming the heat generating element as the pressure generating means, so that the liquid temperature adjusting function is provided in the ink jet head. Even if a filter function is added, it is possible to suppress an increase in head manufacturing cost. Further, as described above, if a driver for driving the heater can be formed at the same time as the heating element, the cost can be further reduced.

  By the way, when a membrane is formed on a silicon substrate, the membrane is preferably composed of at least one layer of a film having a tensile stress at room temperature. For example, a silicon oxide film on a silicon substrate usually shows compressibility regardless of the film formation method and conditions, but as another configuration, an inkjet head in which an interlayer insulating film and a protective film are also plasma CVD silicon oxide films was produced. . As a result, there were many problems that the membrane undulated and contacted the nozzle plate, or the membrane was damaged during the process.

  Therefore, as in the configuration of this example, a silicon nitride film by plasma CVD that has tensile stress and whose stress value can be controlled by film forming conditions is formed as an interlayer insulating film and a protective film, and the stress of the entire membrane Adjusted. As a result, there was no problem that the membrane waved and the volume of the common liquid chamber varied within the head, and the membrane cracking could be suppressed.

  Using the ink jet head manufactured as described above, the temperature of the liquid in the common liquid chamber and the connection port is feedback-controlled while monitoring a temperature sensor (not shown), and the heater on the membrane is energized. The liquid was heated so that the liquid viscosity was about 4 mPa · s. An ink having a viscosity of about 15 mPa · s at room temperature was used. As a result, the ejection frequency from the plurality of nozzles connected to the common liquid chamber is changed from 1 kHz to 10 kHz, that is, the ink flow rate in the ink jet head is changed, and the droplet velocity and the droplet volume of each nozzle are within the specification range ± It was within 15%. Also, no defects such as dust clogging at the nozzle were found.

  In addition, for each drive frequency and number of drive nozzles (= ink liquid flow rate), a look-up table that measures the ink liquid temperature in the common liquid chamber with respect to the heater output was created in advance, and the heater output was controlled based on the lookup table. . As a result, the droplet velocity and the droplet volume could be kept within the specified range (within ± 15%) with any nozzle as in the former. Also, no defects such as dust clogging at the nozzle were found. However, when the same evaluation was performed without energizing the heater, dust clogging at the nozzle was not confirmed, but as the drive frequency increased, the droplet volume and droplet velocity changed and deviated from the specification range. .

  FIG. 31 is an exploded perspective view showing a schematic configuration of an ink jet head according to the fourth embodiment of the present invention. FIG. 32 is a schematic sectional view. In both figures, the same reference numerals as those in FIGS. 14 and 16 denote the same components. The inkjet head 4 of the fourth embodiment shown in FIG. 31 is an edge shooter type inkjet head in which the nozzle plate 10 is disposed on the edge of the substrate 30. In the inkjet head 4 according to the fourth embodiment shown in FIG. 31 and FIG. 32, the individual liquid chamber 21 is arranged such that the partition wall member 23 is sandwiched by the substrate 90 different from the silicon substrate 30 on which the heat generating element 35 is formed. The fluid resistance 36 and the common liquid chamber 23 are formed. The membrane 38 in which the heater 42 and the minute hole 41 are formed in the third embodiment is formed on the substrate 90 together with the connection port 39. The substrate 90 is formed of a silicon substrate, and the membrane 38 is formed by laminating a thermal oxide film 91 on the substrate surface, a resistance layer 92 made of tantalum nitride serving as the heater 42, and silicon nitride films 93 and 94 formed by LPCVD.

FIG. 33 is a process cross-sectional view illustrating a manufacturing process of a substrate portion in the ink jet head of the fourth embodiment. In the figure, the same reference numerals as those in FIG. 32 denote the same components.
First, as shown in FIG. 33A, a 0.5 to 2 μm thermal oxide film 91 is formed on a silicon substrate 95 having a crystal orientation (100). Further, a silicon nitride film 93 is formed in a thickness of 0.3 to 1 μm by LPCVD. Next, as shown in FIG. 33B, a tantalum nitride film to be the resistance layer 92 is formed to a thickness of about 0.1 to 1 μm by sputtering and patterned by a well-known photolithography process. Then, as shown in FIG. 33C, the silicon nitride film 94 is again formed by 0.3 to 1 μm by LPCVD, and the portions of the silicon nitride films 93 and 94 and the thermal oxide film 91 that become the microholes 41 are dried. Remove by etching. Next, as shown in FIG. 33 (d), the silicon substrate 95 having the crystal orientation (100) is etched by anisotropic wet etching using TMAH to form the connection port 39.

  In the inkjet head 4 of the fourth embodiment manufactured by such a manufacturing process, the liquid temperatures of the common liquid chamber 23 and the connection port 39 are set to the membrane 38 as in the above-described third embodiment. While controlling the temperature with the upper heater 42, the injection frequency from the plurality of nozzles 12 connected to the common liquid chamber 23 was changed from 1 kHz to 10 kHz. As a result, the droplet velocity and the droplet volume could be kept within the specified range (within ± 15%) with any nozzle, and no defects such as dust clogging at the nozzle were confirmed. However, when the same evaluation is performed without energizing the heater 42, as the drive frequency increases, the droplet volume and the droplet velocity change and deviate from the specification range, which is the same as in the third embodiment. The phenomenon was confirmed.

  On the other hand, the ink jet head 5 as the fifth embodiment shown in FIG. 34 is provided with a membrane having a minute hole in the common liquid chamber, thereby confirming an effect different from the original purpose. That is, the inkjet head 5 of the fifth embodiment is the same as the inkjet head 3 of the third embodiment shown in FIG. 16, except that the interlayer insulating film 45 and the protective film 48 made of a silicon nitride film are formed by plasma CVD. This is an inkjet head manufactured by including the membrane 38 that is changed in the range of the tensile stress 0 to 0.3 GPa remaining in the membrane 38 by changing the conditions. Using the inkjet head 5 thus manufactured, ink is ejected from a plurality of nozzles, and during that time, the displacement of the ink meniscus 96 at the nozzle 12 that is not ejected is measured by a laser Doppler vibration displacement measuring instrument 97 as shown in FIG. did. As a result, it was confirmed that the vibration displacement of the meniscus 96 of the inkjet head 5 having a residual stress of about 0 GPa is smaller than that of the inkjet head having a residual stress of about 0.3 GPa. This means that crosstalk due to ink liquid pressure generated during ejection between a plurality of nozzles can be reduced. Therefore, using a transparent ink, the displacement of the membrane 38 being driven was measured by a laser Doppler vibration displacement measuring machine from the connection port 39 side which is an ink supply port. As a result, it can be seen that the greater the displacement of the membrane 38, the smaller the vibration displacement of the meniscus 96. By allowing the membrane 38 to be displaced according to the pressure in the common liquid chamber 23, crosstalk between a plurality of nozzles can be reduced. Was confirmed. In terms of crosstalk, it is preferable to increase the volume of the common liquid chamber 23. However, in order to effectively heat and control the temperature of the ink liquid in the common liquid chamber 23, the volume of the common liquid chamber 23 may be decreased. desirable. Thus, the contradictory problem can be solved by making the membrane 38 displaceable by the pressure fluctuation in the common liquid chamber 23 during injection (membrane rigidity).

  The ink jet heads of the third to fifth embodiments described above employ a heat generating element as pressure generating means for ejecting ink liquid from a nozzle. For example, a well-known piezo element Electromechanical conversion elements such as shape memory alloy elements that deform greatly when heat is applied, or an electric field is applied between two fixed and movable plate electrodes facing each other through a minute gap to deform the movable plate electrode It can be applied to any pressure generating means such as an electrostatic actuator element.

Further, as described above, the heater 42 is disposed in the arrangement direction of the nozzles 12, but the shape is not limited to this as long as it is disposed on the membrane 38. For example, the heater 42 is disposed in the direction shown in FIG. You may arrange | position, and as shown in FIG. 36, you may excrete in mesh shape. As shown in FIG. 37, the control may be divided into a plurality of parts. Further, the membrane 38 is constituted by only one in the common liquid chamber 23, but it may be constituted by a plurality of membranes 38 as shown in FIG. Furthermore, the membrane 38 has been composed of a plurality film, an exothermic material, and as long as the material has corrosion resistance to ink jetting, may constitute a membrane 38 as shown in FIG. 39 from a single layer Absent. For example, it is possible to use SUS316 foil that has corrosion resistance to a plurality of chemical liquids and inks and that can generate heat when energized with relatively high resistance. In addition, the member itself constituting the membrane 38 does not generate heat, but has high thermal conductivity as in the inkjet head shown in FIG. 41 which is a cross-sectional view taken along the line Q-Q 'in FIG. 40 and FIG. A configuration in which a separate heater 99 is provided around the membrane 7 made of a material to raise the temperature of the membrane 38 can also be applied.

  Next, as another invention, an outline of an ink liquid supply path of an ink jet recording apparatus capable of mounting the above-described ink jet head will be described with reference to FIG.

  The ink jet recording apparatus 100 shown in FIG. 42 mainly includes an ink jet head 101, an ink receiving portion 102, an ink tank 103, a sub ink tank 104, an ink cartridge 105, a supply pump 106, and a collection / replenishment pump 107. And an ink supply / collection system. The ink jet head 101 is connected to the sub ink tank 104 via the ink supply path 109 and the supply valve 110 at the ink supply port 108. The ink receiver 102 is connected to the ink tank 103 via a filter 111, a recovery valve 112, and a recovery / replenishment pump 107 on the way. The sub ink tank 104 is connected to the supply pump 106, and the ink cartridge 105 is connected to the ink tank 103 via the filter 113, the supply valve 114, and the recovery / supply pump 107. Further, the ink tank 103 is provided with a remaining ink sensor 115 and an air release valve 116. The air release valve 116 is normally open at all times and is closed so as not to cause liquid leakage only during transportation. The sub ink tank 104 and the ink supply path 109 are provided with heaters 117 and 118, respectively, so that the temperature of the ejected ink liquid can be adjusted together with the heater of the partition wall 22 made of the electrothermal conversion material described above. Yes.

  Here, main ink supply / recovery modes include a print mode, a recovery mode, and a replenishment mode. The print mode is a mode in which ink liquid is supplied to the inkjet head 101 during image formation. The supply pump 106 is not operated and the supply valve 110 is opened. Ink supply to the inkjet head 101 is performed by capillary force in the order of the sub ink tank 104, the ink supply path 109 (supply valve 110), and the ink supply port 108. After the temperature is raised above a certain level in the sub ink tank 104, the ambient temperature and the image density / number of prints (ink supply amount) are reflected, and the temperature is adjusted by the heater of the partition wall 22 or the ink supply path 109. Since it is possible to maintain a constant temperature from the supply path to the ink jet head 101 to the partition of the individual liquid chamber in the ink jet head, the liquid temperature in the individual liquid chamber can be made uniform regardless of the ejection amount for each nozzle. . The recovery mode is for the purpose of eliminating ink discharge failure such as initial filling of ink into the ink jet head 101, thickening of ink in non-ejection nozzles and clogging of dust, and air bubbles remaining in the common liquid chamber. Executed. The supply pump 106 is operated with the supply valve 110 open, and the ink is supplied to the inkjet head 101 through the ink tank 103, the sub ink tank 104, the ink supply path 109 (supply valve 110), and the ink supply port 108 in this order. To force supply. As the ink pressure in the entire liquid chamber of the inkjet head 101 increases, the ink is forcibly discharged from the nozzles to the ink receiving portion 102. The discharged ink is returned to the ink tank 103 via the filter 111 and the recovery valve 112 by operating the recovery / supply pump 107 with the supply valve 114 closed for reuse. The replenishment mode is a mode in which ink is replenished from the ink cartridge 105 to the ink tank 103. When the ink remaining amount detection sensor 115 determines that the ink in the ink tank 103 is below the specified level, the supply valve 110 and the recovery valve 112 are turned on. The ink is supplied from the ink cartridge 105 to the ink tank 103 by driving the collection / supply pump 107 with the supply valve 114 closed and the supply valve 114 opened. When it is determined by the ink remaining amount detection sensor 115 that the specified amount is satisfied, the collection / replenishment pump 107 is stopped.

  FIG. 43 is a schematic perspective view showing a schematic configuration of an ink jet recording apparatus according to an embodiment of another invention. The ink jet recording apparatus according to the present embodiment shown in the figure includes two guide shafts 120 extending in parallel and a carriage 121 movable along the guide shaft 120. The carriage 121 is a carriage drive pulse (not shown). Reciprocating scanning is performed along the guide shaft 120 by a driving force transmission mechanism such as a motor and a belt for transmitting the driving force. The inkjet head 124 can be exchanged and attached to the carriage 121 through a connector (not shown), and can be used properly depending on the type of ink liquid to be ejected. A maintenance / recovery system unit 125 is provided at the left end of the movable area of the carriage 121 so as to face the nozzle surface of the ink jet head 124, and during non-ejection, the nozzle surface is capped to suppress drying and eject. If the mouth becomes dirty, wipe it with a wiper. Note that the ink receiving portion 102 shown in FIG. 42 can also be provided. The recording medium 122 is conveyed by the feed roller 126 to the lower part of the carriage 121 in conjunction with the reciprocating scanning of the inkjet head 124 mounted on the carriage 121. The recording medium 122 is supported by a support member 123 below the moving area of the carriage 121, and the distance between the recording medium 122 and the inkjet head 124 can be adjusted by the upper and lower portions of the support member 123. After recording is performed on a necessary portion on the recording medium 122 while alternately feeding the recording medium 122 and scanning the carriage 121 and ejecting ink liquid, the recording medium 122 is discharged to the front of the apparatus.

  FIG. 44 is a block diagram showing an outline of a control unit in an ink jet recording apparatus of another invention. The control unit in the inkjet recording apparatus shown in the figure mainly includes a CPU 131, ROM 132, EEPROM 133, RAM 134, image memory 135, external device interface 136, head control unit 138 for controlling image recording of the inkjet head 137, and FIG. A motor controller 140 for controlling the feed roller 126 and the motor 139 for driving the carriage 121, and an ink supply / maintenance / recovery device 141 for performing ink supply to the inkjet head 137 and wiping / capping of the nozzle surface. An ink supply / maintenance / recovery control unit 142 for controlling, and a heater control unit 144 for controlling the heater 143 provided by monitoring the temperature of each part of the ink jet recording apparatus are configured. Through It is connected to the stomach. The CPU 131 controls each unit connected to the internal bus 145 based on a control program stored in the ROM 132, and the head control unit 138, motor control unit 140, ink supply / maintenance / recovery control unit 142, and heater control unit 144 Data or the like generated by the operation or processing in the printer is output to an external device 146 such as a personal computer (PC) or a digital camera through the external device interface 136. The EEPROM 133 is a rewritable nonvolatile memory, for example, stores user-specific device settings, usage history information, and the like, and is retained even after the printer is turned off. The RAM 134 is a rewritable volatile memory, and temporarily stores various intermediate processing data generated when the ink liquid ejecting apparatus operates. The image memory 135 is composed of an inexpensive DRAM, and print data sent from an external device 146 such as a PC via the external device interface 136, or image data read when a scanner head is mounted as a functional head, for example. Etc. are temporarily saved.

  As described above, in the ink jet recording apparatus 100 of the embodiment shown in FIG. 42, the ink jet head 101 and the ink tank 103, the sub ink tank 104, or the ink cartridge 105 for storing the ink liquid supplied to the ink jet head 101 are used. As shown in FIG. 45 as another form, the inkjet head 101 and the head cartridge 150 including at least one of the ink tank, the sub ink tank, and the ink cartridge are integrated. It is also possible to form.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and substitutions are possible as long as they are described within the scope of the claims.

It is a figure which shows the structure of the inkjet head which concerns on the 1st Example of this invention. 1 is an exploded plan view of an ink jet head according to a first embodiment. It is a time chart which shows the electricity supply control to the partition of the outer wall part in the inkjet head of this Embodiment. It is a top view which shows the wiring which supplies with electricity only to the partition inside the inkjet head of a 1st embodiment. It is a fragmentary sectional view which shows a mode that the protective film was formed in the partition inside the inkjet head of 1st Embodiment. It is a fragmentary sectional view which shows the mode of the electricity supply to the partition in the case of another pressure generation type. It is a fragmentary sectional view which shows the example which provided the insulating member in the partition member surface. It is a fragmentary sectional view which shows the example which provided the thermal-stress buffer material in the partition member surface. It is a figure which shows the structure of the inkjet head which concerns on the 2nd Example of this invention. It is a figure which shows another electricity supply wiring to the partition inside the inkjet head of a 2nd embodiment. It is a figure which shows another electricity supply wiring to the partition inside the inkjet head of a 2nd embodiment. It is a figure which shows another electricity supply wiring to the partition inside the inkjet head of a 2nd embodiment. It is a figure which shows another electricity supply wiring to the partition inside the inkjet head of a 2nd embodiment. It is a disassembled perspective view which shows the structure of the inkjet head which concerns on the 3rd Embodiment of this invention. It is a top view of the inkjet head of the example of a 3rd embodiment. FIG. 16 is a cross-sectional view taken along line P-P ′ in FIG. 15. It is process sectional drawing which shows the outline of the manufacturing process of the inkjet head of the example of 3rd Embodiment. It is process sectional drawing which shows the outline of the manufacturing process of the inkjet head of the example of 3rd Embodiment. It is process sectional drawing which shows the outline of the manufacturing process of the inkjet head of the example of 3rd Embodiment. It is process sectional drawing which shows the outline of the manufacturing process of the inkjet head of the example of 3rd Embodiment. It is process sectional drawing which shows the outline of the manufacturing process of the inkjet head of the example of 3rd Embodiment. It is process sectional drawing which shows the outline of the manufacturing process of the inkjet head of the example of 3rd Embodiment. It is process sectional drawing which shows the outline of the manufacturing process of the inkjet head of the example of 3rd Embodiment. It is process sectional drawing which shows the outline of the manufacturing process of the inkjet head of the example of 3rd Embodiment. It is process sectional drawing which shows the outline of the manufacturing process of the inkjet head of the example of 3rd Embodiment. It is process sectional drawing which shows the outline of the manufacturing process of the inkjet head of the example of 3rd Embodiment. It is process sectional drawing which shows the outline of the manufacturing process of the inkjet head of the example of 3rd Embodiment. It is process sectional drawing which shows the outline of another preparation process of the inkjet head of 3rd Example. It is process sectional drawing which shows the outline of another preparation process of the inkjet head of 3rd Example. It is process sectional drawing which shows the outline of another preparation process of the inkjet head of 3rd Example. It is a disassembled perspective view which shows the structure of the inkjet head which concerns on the 4th Example of this invention. It is a schematic sectional drawing which shows the structure of the inkjet head which concerns on the 4th Example of this invention. It is process sectional drawing which shows the production process of the board | substrate part in the inkjet head of the example of 4th Embodiment. It is a schematic sectional drawing which shows the structure of the inkjet head which concerns on the 5th Example of this invention. It is a top view which shows the wiring to a heater. It is a top view which shows another wiring to a heater. It is a top view which shows another wiring to a heater. It is a top view which shows another wiring to the heater in a some membrane. It is a schematic sectional drawing which shows the structure of a single layer protective film. It is a top view which shows a mode that the separate heater was arrange | positioned around the membrane. It is the Q-Q 'line sectional drawing of FIG. It is a figure which shows schematic structure of the ink liquid supply path | route of the inkjet recording device which concerns on one embodiment of another invention. It is a schematic perspective view which shows schematic structure of the inkjet recording device which concerns on one embodiment of another invention. It is a block diagram which shows the outline of the control part in the inkjet recording device of another invention. It is a perspective view which shows an integrated head cartridge.

Explanation of symbols

1 to 5; inkjet head, 10; nozzle plate,
11; liquid repellent film, 12; nozzle, 13; dummy nozzle, 20; partition member,
21; individual liquid chambers, 22a, 22b; partition walls, 23; common liquid chambers,
24; supply port; 25; dummy liquid chamber; 30; substrate;
31: Pressure generating means, 40: Power source.

Claims (6)

A plurality of nozzles for ejecting ink liquid as droplets, a plurality of individual liquid chambers each holding an ink liquid corresponding to each of the nozzles, a partition constituting the individual liquid chamber, and the individual In an inkjet head having pressure generating means for generating pressure in the ink liquid in the liquid chamber,
The base material to be the partition wall is formed of a metal member having an electric insulating film formed on a surface in contact with the ink liquid, and the ink liquid in the individual liquid chamber is heated by energizing the partition wall to raise the temperature. Inkjet head characterized.   2. The ink jet head according to claim 1, wherein the partition wall between the adjacent individual liquid chambers is energized to generate heat.   3. An ink jet head according to claim 2, wherein all of the partition walls between the individual liquid chambers form a single current path made of a single member.   The plurality of individual liquid chambers are arranged in large numbers, and at least one or more dummy liquid chambers and nozzles that are not used for recording are formed at both ends. Inkjet head. Head cartridge you comprising: the ink jet head; and a ink container for storing ink liquid supplied to the ink jet head to claim 1. 5. The ink jet head according to claim 1, or the head cartridge according to claim 5, and a moving means for relatively moving a recording medium to which the ink liquid ejected from the ink jet head is attached. an ink jet recording apparatus said.

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