JP2006192765A - Liquid ejection head, liquid cartridge and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the inside of gap cannot be completely shut from the outside air, even if an etching hole is sealed when forming the gap by sacrifice layer etching, and the operation of a diaphragm becomes instable by the fluctuation in pressure within an actuator drive chamber to vary the ejection characteristic. <P>SOLUTION: The actuator substrate 1 comprises the diaphragm 12 and an electrode 14 which are disposed facing with each other via a void 13 formed by the sacrifice layer etching, and the sacrifice layer hole 30 to remove the sacrifice layer is sealed with a silicon oxide film 28 which constitutes a part of the diaphragm 12 as a sealing film, forming a corrosion resistant film 29 on the silicon oxide film 28. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a droplet discharge head, a liquid cartridge, and an image forming apparatus.

  For example, as an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, a plotter, etc., a nozzle that discharges a recording liquid droplet and a liquid chamber (discharge chamber, pressure chamber, pressurizing chamber, ink flow path) communicating with the nozzle are used. And a variable electrode constituting at least a part of the diaphragm forming the wall surface of the liquid chamber, and a counter electrode facing the variable electrode, and a voltage is applied between the electrodes. An electrostatic actuator that discharges droplets from the nozzle by displacing the variable electrode (vibrating plate) with electrostatic force and generating pressure in the liquid chamber by the mechanical restoring force of the vibrating plate is provided. Some have a droplet discharge head (electrostatic head) mounted as a recording head.

  In such an electrostatic head, a minute gap (gap) must be formed with high precision. As a method for forming the minute gap, an actuator substrate, a diaphragm and a liquid chamber formed with a gap step are formed. However, in this case, it is not sufficient to ensure the gap processing accuracy and the rigidity of the partition wall between the liquid chambers.

  Therefore, an actuator substrate in which a diaphragm and an electrode are arranged to face each other via a gap formed by sacrificial layer etching and a liquid chamber substrate (flow path substrate) in which a liquid chamber is formed are joined.

  However, when the gap is formed by sacrificial layer etching, the sacrificial layer removal hole (hereinafter referred to as “sacrificial layer hole”) used to remove the sacrificial layer in order to maintain airtightness in the gap after the formation. ) Must be sealed. That is, in the electrostatic head, if the airtightness of the gap is insufficient, the displacement amount of the diaphragm is varied, leading to a decrease in driving reliability of the electrostatic head.

Therefore, as a conventional electrostatic head, a sacrificial layer hole is sealed with an organic resin film such as polyimide or polybenzoxazole as described in Patent Document 1, or described in Patent Document 2. It is known that the sacrificial layer hole is sealed with a metal film such as Ni.
JP 2004-98425 A Japanese Patent No. 3500636

Here, an example of a conventional electrostatic head will be described with reference to FIGS.
This electrostatic head is formed by laminating a nozzle substrate 501 having a nozzle 511 for discharging droplets, a flow path substrate 502 having a liquid chamber 521 communicating with the nozzle 511, and an actuator substrate 503 including an electrostatic actuator. And joined.

  In the actuator substrate 503, a thermal oxide film 532 is formed on a silicon substrate 531, a fixed electrode 533 is formed on the thermal oxide film 532, and an insulating film 534 and a sacrificial layer 535 are sequentially stacked on the fixed electrode 533. A silicon oxide film 537, a polysilicon film 538 serving as a variable electrode, a silicon nitride film 539, and a silicon oxide film 540 are sequentially stacked to form a diaphragm 536 that forms the wall surface of the liquid chamber 521 on the sacrificial layer 535. After forming the gap 542 by removing the sacrificial layer 535 between the fixed electrode 533 and the diaphragm 536 through the sacrificial layer removal hole (sacrificial layer hole) 541 formed on the diaphragm 536, the gap 542 is formed on the surface of the diaphragm 536. The sacrificial layer hole 541 is sealed by forming the corrosion resistant film 543.

  As described above, the electrostatic head discharges droplets by the displacement of the diaphragm, and variation in the amount of displacement of the diaphragm greatly affects the discharge performance, so that the airtightness of the gap can be maintained. is important. In particular, regarding the gap formed by the sacrificial layer etching, how to seal the sacrificial layer hole is an important issue. When the airtightness of the gap is insufficient, the pressure in the gap fluctuates during continuous driving, thereby causing variations in the displacement of the diaphragm. In particular, when the electrostatic head is driven at a high frequency, this phenomenon is remarkable, and the discharge performance is clearly reduced.

  However, when the sacrificial layer hole is sealed with an organic resin film such as polyimide or polybenzoxazole, it is difficult to maintain the airtightness of the gap due to the air permeability of the organic resin film. Variations occur in the internal pressure of the gap, resulting in variations in the displacement of the diaphragm.

  In addition, in such a structure having air permeability, the influence of the outside world cannot be ignored, and the diaphragm is deformed by changes in temperature and humidity, and the effective gap length fluctuates or partially vibrates. Problems such as adhesion between the plate and the electrode have arisen.

  Further, when an organic resin film is used as a sealing material, as shown in FIG. 17, there arises a problem that the sealing material forming the organic resin film penetrates into the gap 542, leading to a decrease in manufacturing yield. There is also a problem.

  In addition, when a metal film such as Ni is used as a sealing material, the coverage at the time of film formation is inferior, so that the step coverage in the sacrificial layer hole deteriorates and it is difficult to ensure airtightness. is there.

  The present invention has been made in view of the above problems, and provides a liquid droplet ejection head capable of reliably sealing a gap and obtaining stable ejection performance, a liquid cartridge including the liquid droplet ejection head, and an image forming apparatus. The purpose is to do.

  In order to solve the above problems, in the liquid droplet ejection head according to the present invention, the sacrificial layer removal hole for forming a void is sealed with a sealing film made of an insulating film or a laminated film of an insulating film and a conductive film. It was set as the structure.

  Here, the insulating film constituting the sealing film is preferably a silicon oxide film. Further, it is preferable that the sealing film constitutes a part of the diaphragm.

  The sealing film is preferably a laminated film of a silicon oxide film and a polysilicon film. In this case, it is preferable that the silicon oxide film constitutes a part of the diaphragm.

  Furthermore, it is preferable to have a corrosion-resistant film as an upper layer of the sealing film. In this case, it is preferable that the corrosion resistant film formed on the upper layer of the sealing film is an organic resin film.

  Moreover, it is preferable that the film thickness of a sealing film is 2 times or more of a space | gap, and is 1/2 or less of the diameter of a sacrifice layer removal hole.

  The liquid cartridge according to the present invention has a configuration in which the droplet discharge head according to the present invention is integrally provided.

  The image forming apparatus according to the present invention is configured to mount the liquid droplet ejection head according to the present invention or the liquid cartridge according to the present invention.

  According to the droplet discharge head according to the present invention, the sacrificial layer removal hole for forming the gap is sealed with the sealing film made of the insulating film or the laminated film of the insulating film and the conductive film. It can be surely hermetically sealed and stable ejection performance can be obtained.

  According to the liquid cartridge according to the present invention, since the liquid droplet ejection head according to the present invention is integrally provided, the gap can be surely hermetically sealed, and stable ejection performance can be obtained.

  According to the image forming apparatus of the present invention, since the liquid droplet ejection head according to the present invention or the liquid cartridge including the liquid ejection head is provided, the ejection performance is stable and high-quality recording can be performed.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a first embodiment of a droplet discharge head according to the present invention will be described with reference to FIGS. 1 is a plan sectional view of the head, FIG. 2 is a plan sectional view of the head in an exploded state, FIG. 3 is an enlarged plan sectional view of part A in FIG. 2, and FIG. FIG. 5 is an explanatory cross-sectional view taken along line X-Y, FIG. 5 is an explanatory cross-sectional view taken along line YY in FIG. 3, and FIG.

  The inkjet head, which is an electrostatic droplet discharge head, is configured by sequentially laminating an actuator substrate 1, a flow path substrate 2, and a nozzle substrate 3, and by bonding these three substrates 1, 2, and 3, A nozzle 4 for discharging droplets forms a liquid chamber 6 that communicates via a nozzle communication path 5, a fluid resistance portion 7 for supplying a recording liquid (ink) to the liquid chamber 6, and an ink supply hole 8. Each liquid chamber 6 is partitioned by a liquid chamber interval wall 9.

  Actuator elements 11 are formed on the actuator substrate 1 corresponding to the respective liquid chambers 6. The actuator element 11 includes a diaphragm 12 that forms part of the wall surface of the liquid chamber 6, and an electrode (individual electrode) 14 that faces the diaphragm 12 via a gap (gap) 13 formed by sacrificial layer etching. It consists of.

  In addition, the ink supply hole 8 of the flow path substrate 2 faces the actuator substrate 1 to form an ink supply path 15 through which ink is supplied from the outside.

  The flow path substrate 2 is formed, for example, by anisotropically etching a single crystal silicon substrate having a crystal plane orientation (110) with a strong alkaline etching solution such as a KOH aqueous solution, and the actuator substrate 1 and the flow path substrate 2. Are integrated by adhesive bonding.

  The nozzle substrate 3 is formed of a metal plate such as Ni or SUS, ceramics, glass, or resin, and the nozzle 4 can be formed by a known method such as dry or wet etching or laser processing. In addition, a water repellent film is formed on the ejection direction surface of the nozzle substrate 3 by a known method such as a plating film or a water repellent coating in order to ensure water repellency with ink.

  Here, in the actuator substrate 1, as shown in FIGS. 4 and 5, an insulating film such as a thermal oxide film 22 is formed on the silicon substrate 21, and the fixed electrode 14 is formed on the thermal oxide film 22. Yes. Here, the diaphragm 12 facing the electrode 14 via the gap 13 includes a silicon oxide film 25 that is an insulating film and a polysilicon film that is a variable electrode (diaphragm electrode) patterned into a required shape from below. 26, a silicon nitride film 27 as an insulating film and a silicon oxide film 28 as an insulating film.

  Polysilicon is used as the variable electrode material, but as the electrode material, a material having high temperature resistance, excellent workability, and less film surface unevenness is preferable. Other than polysilicon, a refractory metal such as TiN is used. Materials can also be used. Further, the insulating film 23 on the fixed electrode side formed on the electrode 14, the silicon oxide film 25 and the silicon nitride film 27 formed on the electrode 14 side of the polysilicon film 26 which is a variable electrode of the diaphragm 12 are sacrifice layer etching. In addition to being used as an anti-etching mask, the electrode 14 and the diaphragm 12 are prevented from being damaged by a short circuit or electric discharge, and also serve as a spacer for the gap 13.

  The gap 13 forms a sacrificial layer hole 30 after forming the silicon oxide film 25, the polysilicon film 26, and the silicon nitride film 27 constituting the diaphragm 12, and is insulated from the insulating film 23 through the sacrificial layer hole 30. Of the sacrificial layer 24 formed between the film 25, the sacrificial layer 24 between the diaphragm 12 and the electrode 14 is removed by sacrificial layer etching.

  By forming the silicon oxide film 28 after this sacrificial layer etching, the sacrificial layer hole 30 is sealed and the final step of the diaphragm 12 is simultaneously formed.

  A corrosion-resistant film 29 for preventing ink from being immersed in the actuator portion is formed on the upper layer of the vibration plate 12. As the corrosion resistant film 29, an organic resin film such as polyimide or polybenzoxazole is used.

  In this case, as shown in FIG. 6, the film thickness T of the silicon oxide film 28 constituting the sealing film is more than twice the depth g of the gap 13 and is 2 times the diameter a of the sacrificial layer hole 30. It is preferable that it is 1 or less. When the film thickness T is thinner than this, the sealing performance is incomplete, and when it is thick, the total thickness of the diaphragm 12 becomes thick, leading to an increase in driving voltage. By being within this range, sealing can be performed reliably and an increase in drive voltage can be suppressed.

  Further, the electrode 14 is connected to the electrode pad portion 17 through the connection portion 16 as shown in FIG.

An example of the manufacturing process (manufacturing method) of the actuator substrate 1 in this head will be described with reference to FIGS.
First, as shown in FIG. 7A, a thermal oxide film 22 is formed on a silicon substrate 21 to a thickness of 1.5 μm, and a polysilicon film 34 is formed as a fixed individual electrode 14 on the thermal oxide film 22 to a thickness of 0.5 μm. Form with. Thereafter, in order to lower the electrical resistance of the polysilicon film, impurities such as phosphorus are doped by thermal diffusion.

  Next, as shown in FIG. 7B, the polysilicon film 34 is patterned into a desired electrode shape by lithoetch to form the individual electrode 14, and an insulating film 23 as an individual electrode side protective film is formed thereon, for example, A silicon oxide film is formed to a thickness of 0.15 μm by CVD.

  Thereafter, as shown in FIG. 7C, a polysilicon film having a thickness of 0.2 μm is formed as the sacrificial layer 24 to form a desired pattern. The thickness of the sacrificial layer 24 formed here is the depth g (gap length) of the gap 13. Next, as shown in FIG. 7D, a silicon oxide film 25 is formed on the sacrificial layer 24 to a thickness of 0.15 μm, and a polysilicon film 36 to be the variable electrode 26 is formed to a thickness of 0.2 μm, both of which are CVD. Are sequentially formed. Here, an impurity such as phosphorus or boron is doped by ion implantation or thermal diffusion in order to lower the electrical resistance of the polysilicon film 36 used as an electrode.

  Thereafter, as shown in FIG. 7E, a polysilicon film 36 is formed in a desired pattern to form the variable electrode 26, and then a silicon nitride film (insulating film) 27 is formed to a thickness of 0.1 μm. Here, the silicon nitride film 27 is used as an etching resistant mask for the polysilicon film 36 that is the variable electrode 26 and also functions as a film for adjusting the internal stress of the diaphragm 12 formed of a laminated film. In other words, the silicon nitride film 27 has a tensile stress while the other silicon oxide films 25 and 28 or the polysilicon film 36 have a compressive stress, which greatly affects the bending of the diaphragm 12. Care must be taken in setting the film thickness.

Next, as shown in FIG. 8A, a sacrificial layer hole 30 is formed corresponding to the region where the gap 13 is to be formed, and then as shown in FIG. 8B, the sacrificial layer hole 30 is sacrificed. A gap 13 is formed by removing the sacrificial layer 24 at a required portion by layer etching. Here, the sacrificial layer etching is performed by wet etching using TMAH (tetramethylammonium hydroxide aqueous solution) or dry etching using SF ₆ or XeF ₂ gas. In consideration of damage to the individual electrode side insulating film 23 in the gap 13 and the silicon oxide film 25 on the diaphragm 12 side and throughput, wet etching is preferable.

  Then, as shown in FIG. 8C, a silicon oxide film 28 as a sealing film for sealing the sacrificial layer hole 30 is formed, and at the same time as the sacrificial layer hole 30 is sealed, the diaphragm 12 is formed. Here, as described above, the silicon oxide film 28 is formed to be not less than twice the depth of the gap 13 and not more than half the diameter of the sacrificial layer hole 30, thereby ensuring a reliable gap. Can be sealed.

  In the present embodiment, since the gap 13 has a depth of 0.2 μm and the sacrificial layer hole 30 has a diameter of 1.2 μm, the thickness of the silicon oxide film 28 is 0.6 to 0.00 mm. 8 μm.

  Next, as shown in FIG. 8D, an organic resin film such as polyimide or polybenzoxazole is formed as a silicon oxide film 28 with a thickness of 1.0 μm.

  The actuator substrate 1 is formed through the above manufacturing steps.

  In the head configured as described above, the diaphragm 12 is used as a common electrode, the fixed electrode 14 is used as an individual electrode, and a drive pulse voltage is applied between these electrodes, thereby generating between the diaphragm 12 and the individual electrode 14. The diaphragm 12 is deformed and displaced toward the individual electrode 14 by the electrostatic force. Thereafter, by discharging the drive pulse voltage, the diaphragm 12 is restored and deformed, and droplets are ejected from the nozzle 4 due to the change in the internal volume of the liquid chamber 6 and the action of pressure.

  In this head, the gap is sealed by sealing the sacrificial layer hole used for sacrificial layer etching with an insulating film, so that the airtightness in the gap is ensured, and the air pressure in the gap due to driving is increased. The fluctuation is suppressed, the variation in the displacement of the diaphragm is reduced, and a stable droplet discharge performance is obtained.

  In this case, by using a dense silicon oxide film as the insulating film used as the sealing film, sealing becomes more reliable, the manufacturing process becomes easy, and a head with stable manufacturing quality can be obtained. it can. Furthermore, as described above, by forming a part of the diaphragm with the sacrificial layer hole sealing material (silicon oxide film), the manufacturing method can be simplified and the manufacturing cost can be reduced.

  Also, by forming a corrosion-resistant film on the sealing film that constitutes the diaphragm, the immersion of the recording liquid into the actuator unit is suppressed, and the ejection performance of the head is further stabilized and long-term reliability is improved. Can do.

Next, a second embodiment of the droplet discharge head according to the present invention will be described with reference to FIG.
The feature of the second embodiment is that the sacrificial layer hole 30 is sealed by the silicon oxide film 28 in the first embodiment, whereas the laminated film of the silicon oxide film 28 and the polysilicon film 40 is sealed. It is in a place to be sealed as a film.

  A manufacturing process (manufacturing method) of the actuator substrate 1 of the droplet discharge head will be described with reference to FIG. Since the process until the gap 13 is formed by the sacrificial layer etching is the same as that described in the manufacturing process of the first embodiment, illustration and description thereof are omitted.

  As shown in FIGS. 10A and 10B, after the gap 13 is formed by sacrificial layer etching, a silicon oxide film 28 and a polysilicon film 40 are sequentially formed as a sealing film. Here, the silicon oxide film 28 is formed with a thickness of 0.2 μm, and the polysilicon film 40 is formed with a thickness of 0.5 μm.

  Next, as shown in FIG. 10C, the polysilicon film 40 formed on the vibration plate 12 is removed by anisotropic dry etching. As a result, a structure in which the polysilicon film 40 remains only in the sacrificial layer hole 30 is formed. Therefore, as shown in FIG. 10D, an organic resin film such as polyimide or polybenzoxazole is formed as a corrosion-resistant film 29 with a thickness of 1.0 μm.

  By setting it as such a structure, the diaphragm 12 can be formed thinly compared with 1st Embodiment. That is, since the polysilicon film 40 is mainly used for sealing the sacrificial layer hole 30 and the thickness of the silicon oxide film 28 can be reduced, the overall thickness of the diaphragm 12 can be reduced.

  In the head according to the present embodiment, the actuator element 11 formed with the diaphragm 12 having a short side width of 60 μm, a long side width of 800 to 1000 μm, and a partition wall width of about 24.5 μm is arranged on one side by the above-described configuration and manufacturing method. The head configuration has a nozzle arrangement density of 300 dpi by arranging 384 and two rows in a staggered manner.

Next, a liquid cartridge according to the present invention will be described with reference to FIG.
The head-integrated liquid cartridge 80 includes an ink jet head 82 that is a droplet discharge head according to any of the above embodiments having nozzles 81 and the like, and an ink tank that supplies ink as a recording liquid to the ink jet head 82. 83 is integrated.

  In this way, by integrating the recording liquid tank (liquid tank) that supplies the recording liquid to the droplet discharge head according to the present invention, there is little variation in the droplet discharge characteristics and a highly reliable droplet discharge head is integrated. The liquid cartridge (ink tank integrated head) can be obtained at low cost.

Next, an example of an image forming apparatus according to the present invention equipped with the droplet discharge head according to the present invention will be described with reference to FIGS. FIG. 12 is an explanatory side view for explaining the overall configuration of the image forming apparatus, and FIG. 13 is an explanatory plan view of a main part of the apparatus.
In this image forming apparatus, a carriage 103 is slidably held in a main scanning direction by a guide rod 101 and a guide rail 102 that are horizontally mounted on left and right side plates (not shown), and a timing belt 105 is slid by a main scanning motor 104. 13 is moved and scanned in the direction indicated by the arrow (main scanning direction) in FIG.

  The carriage 103 includes, for example, four recording heads 107 including the liquid ejection heads according to the present invention that eject ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk), respectively. A plurality of ink ejection openings are arranged in a direction crossing the main scanning direction, and are mounted with the ink droplet ejection direction facing downward.

  As described above, the electrostatic liquid discharge head is used as the liquid discharge head constituting the recording head 107. Note that the recording head can also be configured by one or a plurality of liquid ejection heads provided with a plurality of nozzle rows that eject different colors.

  The carriage 103 is equipped with a sub tank 108 for each color for supplying each color ink to the recording head 107. Ink is supplied to the sub tank 108 from a main tank (ink cartridge) (not shown) via an ink supply tube 109.

  On the other hand, as a paper feeding unit for feeding paper 112 stacked on a paper stacking unit (pressure plate) 111 such as a paper feeding cassette 110, a half-moon roller (separately feeding paper 112 one by one from the paper stacking unit 111) A separation pad 114 made of a material having a large friction coefficient is provided opposite to the sheet feeding roller 113 and the sheet feeding roller 113, and the separation pad 114 is urged toward the sheet feeding roller 113 side.

  As a transport unit for transporting the paper 112 fed from the paper feed unit below the recording head 107, a transport belt 121 for electrostatically attracting and transporting the paper 112, and a paper feed unit A counter roller 122 for transporting the paper 112 fed through the guide 115 while sandwiching it between the transport belt 121 and the paper 112 fed substantially vertically upward is changed by about 90 ° and copied on the transport belt 121. A conveying guide 123 for adjusting the pressure and a tip pressure roller 125 urged toward the conveying belt 121 by a pressing member 124. In addition, a charging roller 126 that is a charging unit for charging the surface of the conveyance belt 121 is provided.

  Here, the conveyance belt 121 is an endless belt, is stretched between the conveyance roller 127 and the tension roller 128, and the conveyance roller 127 is rotated from the sub-scanning motor 131 via the timing belt 132 and the timing roller 133. By doing so, it is configured to circulate in the belt conveyance direction (sub-scanning direction) of FIG. A guide member 129 is disposed on the back side of the conveyance belt 121 in correspondence with the image forming area formed by the recording head 107.

  Further, as shown in FIG. 31, a slit disk 134 is attached to the shaft of the transport roller 127, and a sensor 135 for detecting the slit of the slit disk 134 is provided. An encoder 136 is configured.

  The charging roller 126 is arranged so as to contact the surface layer of the conveyor belt 121 and rotate following the rotation of the conveyor belt 121, and applies 2.5N to both ends of the shaft as a pressing force.

  Also, as shown in FIG. 12, an encoder scale 142 having slits is provided on the front side of the carriage 103, and an encoder sensor comprising a transmission type photosensor for detecting the slits of the encoder scale 142 on the front side of the carriage 103. The encoder 144 for detecting the position of the carriage 103 in the main scanning direction is configured by these.

  Further, as a paper discharge unit for discharging the paper 112 recorded by the recording head 107, a separation unit for separating the paper 112 from the conveying belt 121, a paper discharge roller 152 and a paper discharge roller 153, and paper discharge A paper discharge tray 154 for stocking the paper 112 to be printed.

  A double-sided paper feeding unit 161 is detachably attached to the back. The double-sided paper feeding unit 161 takes in the paper 112 returned by the reverse rotation of the transport belt 121, reverses it, and feeds it again between the counter roller 122 and the transport belt 121.

  Further, as shown in FIG. 13, a maintenance / recovery mechanism 191 for maintaining and recovering the state of the nozzles of the recording head 107 is disposed in the non-printing area on one side of the carriage 103 in the scanning direction.

  The maintenance and recovery mechanism 191 includes caps 192a to 192d for capping each nozzle surface of the recording head 107 (referred to as “cap 192” when not distinguished) and a wiper that is a blade member for wiping the nozzle surface. A blade 193 and a blank discharge receptacle 194 for receiving droplets when performing blank discharge for discharging droplets that do not contribute to recording in order to discharge the thickened recording liquid are provided.

  In the image forming apparatus configured as described above, the sheets 112 are separated and fed one by one from the sheet feeding unit, and the sheet 112 fed substantially vertically upward is guided by the guide 115, and includes the conveyance belt 121 and the counter roller 122. The leading end is guided by the conveying guide 123 and pressed against the conveying belt 121 by the leading end pressure roller 125, and the conveying direction is changed by approximately 90 °.

  At this time, a positive voltage output and a negative output are alternately repeated from the high voltage power supply to the charging roller 126 by a control circuit (not shown), that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 121 alternates, that is, In the sub-scanning direction, which is the circumferential direction, plus and minus are alternately charged in a band shape with a predetermined width. When the paper 112 is fed onto the conveyance belt 121 charged alternately with plus and minus, the paper 112 is attracted to the conveyance belt 121 by electrostatic force, and the paper 112 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 121. Is done.

  Therefore, by driving the recording head 107 according to the image signal while moving the carriage 103, ink droplets are ejected onto the stopped paper 112 to record one line, and after the paper 112 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 112 has reached the recording area, the recording operation is finished, and the paper 112 is discharged onto the paper discharge tray 154.

  In the case of double-sided printing, when recording on the front surface (surface to be printed first) is completed, the recording belt 112 is fed into the double-sided paper feeding unit 161 by rotating the conveyor belt 121 in the reverse direction. The paper 112 is reversed (with the back surface being the printing surface), and is fed again between the counter roller 122 and the conveyor belt 121. The timing is controlled, and the sheet is conveyed onto the conveyor bell 121 as described above. After recording on the back side, the sheet is discharged to the discharge tray 154.

  Further, during printing (recording) standby, the carriage 103 is moved to the maintenance / recovery mechanism 191 side, the nozzle surface of the recording head 107 is capped by the cap 192, and the nozzles are kept in a wet state. To prevent. In addition, the recording liquid is sucked from the nozzle in a state where the recording head 107 is capped with the cap 192 (referred to as “nozzle suction” or “head suction”), and a recovery operation is performed to discharge the thickened recording liquid or bubbles. Wiping is performed by the wiper blade 193 in order to clean and remove ink adhering to the nozzle surface of the recording head 107 by this recovery operation. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. Thereby, the stable ejection performance of the recording head 107 is maintained.

  Thus, since this image forming apparatus is equipped with the ink jet head which is the liquid droplet ejection head according to the present invention, there is little variation in the ejection characteristics of the ink droplets and an image forming apparatus capable of recording an image with high image quality. Is obtained.

  As described above, the droplet discharge head has been described as an example of this embodiment, but the electrostatic actuator constituting the actuator of the droplet discharge head according to the present invention is an optical scanning mirror, an optical valve, or the like. It can also be used as an optical device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan sectional explanatory view showing a first embodiment of a droplet discharge head according to the present invention. It is a plane explanatory view of the state which decomposed | disassembled the head similarly. FIG. 3 is an enlarged plan view of an essential part of FIG. 2. FIG. 4 is a cross-sectional explanatory view taken along line XX in FIG. 3. FIG. 4 is a cross-sectional explanatory view taken along line YY in FIG. 3. It is principal part expanded sectional explanatory drawing of FIG. It is sectional explanatory drawing with which it uses for description of the manufacturing process of the actuator board | substrate of the head. FIG. 8 is a cross-sectional explanatory diagram for explaining the process following the step in FIG. 7. FIG. 5 is a cross-sectional explanatory view similar to FIG. 4 showing a second embodiment of a droplet discharge head according to the present invention. It is sectional explanatory drawing with which it uses for description of the manufacturing process of the actuator board | substrate of the head. FIG. 6 is a perspective explanatory view for explaining a liquid cartridge according to the present invention. 1 is an overall configuration diagram illustrating an example of a mechanism unit of an image forming apparatus according to the present invention. Similarly it is principal part plane explanatory drawing. FIG. 5 is a cross-sectional explanatory view similar to FIG. 4 illustrating an example of a conventional electrostatic head. FIG. 6 is a cross-sectional explanatory view similar to FIG. 5. Similarly, it is principal part expanded sectional explanatory drawing of FIG. It is a principal part expanded sectional explanatory drawing of FIG. 14 when the sealing failure similarly arises.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Actuator board | substrate 2 ... Flow path board | substrate 3 ... Nozzle board | substrate 4 ... Nozzle 5 ... Nozzle communication path 6 ... Liquid chamber 7 ... Fluid resistance part 8 ... Ink supply hole 9 ... Liquid chamber space | interval wall 11 ... Actuator element 12 ... Diaphragm 13 ... gap
DESCRIPTION OF SYMBOLS 14 ... Electrode 21 ... Silicon substrate 22 ... Thermal oxide film 23 ... Insulating film 24 ... Sacrificial layer 25 ... Insulating film 26 ... Diaphragm electrode 27 ... Insulating film 28 ... Insulating film 29 ... Corrosion-resistant film 30 ... Sacrificial layer hole (sacrificial) Layer removal hole)

Claims (10)

  A nozzle substrate having nozzles for discharging liquid droplets, a flow path substrate that forms a liquid chamber that communicates with each nozzle, and a vibration that forms part of the wall surface of the liquid chamber via a gap formed by sacrificial layer etching In a droplet discharge head in which an electrostatic actuator substrate having a plate and an electrode arranged opposite to each other is laminated, a sacrificial layer removal hole for forming the gap is a sealing film made of an insulating film or a laminated film of an insulating film and a conductive film. A droplet discharge head, which is sealed with a stop film.   2. The liquid droplet ejection head according to claim 1, wherein the insulating film constituting the sealing film is a silicon oxide film.   3. The liquid droplet ejection head according to claim 1, wherein the sealing film constitutes a part of a vibration plate.   2. The droplet discharge head according to claim 1, wherein the sealing film is a laminated film of a silicon oxide film and a polysilicon film.   5. The droplet discharge head according to claim 4, wherein the silicon oxide film constitutes a part of a diaphragm.   6. The liquid droplet ejection head according to claim 1, further comprising a corrosion-resistant film as an upper layer of the sealing film.   7. The droplet discharge head according to claim 6, wherein the corrosion-resistant film formed on the upper layer of the sealing film is an organic resin film.   6. The droplet discharge head according to claim 1, wherein the sealing film has a film thickness that is not less than twice the gap and not more than one-half of the diameter of the sacrificial layer removal hole. A droplet discharge head that is characterized.   9. A liquid cartridge comprising the droplet discharge head according to claim 1 integrally. An image forming apparatus comprising the droplet discharge head according to claim 1 or the liquid cartridge according to claim 9.

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