JP5691666B2 - Liquid ejection head and image forming apparatus - Google Patents

Description

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

  As an image forming apparatus such as a printer, a facsimile, a copying machine, a plotter, or a complex machine of these, for example, a liquid discharge recording type image forming using a recording head composed of a liquid discharge head (droplet discharge head) that discharges ink droplets. An apparatus (for example, an ink jet recording apparatus) is known. This liquid discharge recording type image forming apparatus means that ink droplets are transported from a recording head (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). Yes, it is also ejected onto a recording medium or a recording medium, recording paper, recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously). And a serial type image forming apparatus that forms an image by ejecting liquid droplets while the recording head moves in the main scanning direction, and a line type head that forms images by ejecting liquid droplets without moving the recording head There are line type image forming apparatuses using

  In the present application, the “image forming apparatus” of the liquid discharge recording method is an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. In addition, “image formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply It also means that a droplet is landed on a medium). “Ink” is not limited to ink, but is used as a general term for all liquids capable of image formation, such as recording liquid, fixing processing liquid, and liquid. DNA samples, resists, pattern materials, resins and the like are also included. The term “paper” is not limited to paper, but includes the above-described OHP sheet, cloth, and the like, and means that ink droplets adhere to the recording medium, recording medium, recording paper, recording It is used as a general term for what includes what is called paper. In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  The liquid ejection head includes a deformable diaphragm member that forms at least one wall surface of a liquid chamber that communicates with a nozzle that ejects droplets, and a stacked piezoelectric that deforms the diaphragm member and pressurizes the liquid in the liquid chamber The diaphragm member is formed by electroforming, and has an island portion including an island-shaped convex portion with which the piezoelectric element abuts and a thin portion around the island-shaped convex portion. A pattern edge portion having an overhang shape with respect to a thin portion is known (Patent Document 1).

  As described above, when the diaphragm member is formed by electroforming, the current density at the time of electroforming is concentrated on the island-shaped convex portions, so that the region having island-shaped convex portions is thick and the region having no island-shaped convex portions. Is formed thinly.

  Therefore, it has been conventionally known that a dummy island portion is provided so that the growth of the electroformed film is made uniform throughout the entire diaphragm member to make the thickness uniform (Patent Document 2).

JP 2004-90297 A Japanese Patent Laid-Open No. 10-100402

  By the way, in the liquid discharge head using the vibration plate member and the piezoelectric element as described above, the joining accuracy between the vibration plate member and the piezoelectric element greatly affects the droplet discharge characteristics (discharge amount and discharge speed). Therefore, in order to form a high-quality image, it is necessary to improve the bonding accuracy between the diaphragm member and the piezoelectric element. In this case, there are various bonding methods such as mechanical fitting and optical methods. In any case, the processing accuracy of the alignment pattern directly affects the bonding accuracy.

  The present invention has been made in view of the above-described problems, and an object thereof is to improve the bonding accuracy between a diaphragm member and a piezoelectric element.

In order to solve the above-described problem, a liquid discharge head according to the present invention includes:
A deformable diaphragm member that forms at least one wall surface of a liquid chamber through which a plurality of nozzles that discharge droplets communicate with each other;
Driving means for deforming the diaphragm member to pressurize the liquid in the liquid chamber;
The diaphragm member is formed by electroforming,
An island-shaped convex portion formed of a thick-walled portion with which the driving means abuts, and an island portion formed of a thin-walled portion around the island-shaped convex portion;
The island-shaped convex portion has an overhang shape portion,
The diaphragm member is formed with an alignment pattern for alignment with the driving means,
The same pattern as the island part is formed on both sides of the alignment pattern in the nozzle arrangement direction.

  Here, the alignment pattern may be a through hole.

  The alignment pattern may be a recess.

  The image forming apparatus according to the present invention includes the liquid discharge head according to the present invention.

  According to the liquid discharge head according to the present invention, the diaphragm member is formed by electroforming, and includes an island-shaped convex portion that is a thick-walled portion that comes into contact with the driving unit and a thin-walled portion around the island-shaped convex portion. The island-shaped convex portion has an overhang-shaped portion, and an alignment pattern for alignment with the driving means is formed on the diaphragm member, and islands are formed on both sides of the alignment pattern in the nozzle arrangement direction. Since the same pattern as the part is formed, the thickness around the alignment pattern is made uniform, the center position accuracy of the alignment pattern is increased, and the diaphragm member and the piezoelectric element are positioned with high accuracy. Can be joined together.

  Since the image forming apparatus according to the present invention includes the liquid ejection head according to the present invention, a high-quality image can be formed.

FIG. 3 is a schematic exploded perspective view illustrating an example of an embodiment of a liquid discharge head according to the present invention including a nozzle plate according to the present invention. It is sectional explanatory drawing along the liquid chamber longitudinal direction of the head. It is sectional explanatory drawing of an example along the liquid chamber transversal direction of the head. It is sectional explanatory drawing of an example along the liquid chamber transversal direction of the head. It is expansion sectional explanatory drawing of the island part with which it uses for description of the manufacturing method by electroforming of a diaphragm member. It is front explanatory drawing of the piezoelectric member joined to a diaphragm member. It is plane explanatory drawing seen from the piezoelectric member side with which it uses for description of the diaphragm member in 1st Embodiment of this invention. It is an enlarged explanatory view showing the alignment pattern portion of the diaphragm member together with a comparative example. It is plane explanatory drawing seen from the piezoelectric member side with which it uses for description of the diaphragm member in 2nd Embodiment of this invention. It is an enlarged explanatory view showing the alignment pattern portion of the diaphragm member together with a comparative example. It is explanatory drawing with which it uses for description of the joining apparatus of the diaphragm member and piezoelectric member of the embodiment. 1 is an explanatory side view illustrating an overall configuration of a mechanism unit as an example of an image forming apparatus according to the present invention. It is principal part plane explanatory drawing of the mechanism part. It is a whole block diagram which shows the other example of the image forming apparatus which concerns on this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of a liquid discharge head according to the present invention will be described with reference to FIGS. 1 is an exploded perspective view of the head, FIG. 2 is a cross-sectional explanatory view along a direction (liquid chamber longitudinal direction) orthogonal to the nozzle arrangement direction of the head, and FIGS. 3 and 4 are nozzle arrangement directions of the head. It is sectional explanatory drawing of the different example along (liquid chamber transversal direction).

  The liquid discharge head includes a flow path plate (also referred to as a flow path substrate or a liquid chamber substrate) 1 formed of a SUS substrate and a vibration plate member that forms a vibration plate bonded to the lower surface of the flow path plate 1. 2 and a nozzle plate 3 joined to the upper surface of the flow channel plate 1, and a plurality of nozzles 4 for discharging droplets (liquid droplets) thereby communicate with each other via a nozzle communication channel 5. A plurality of liquid chambers (also referred to as a pressurized liquid chamber, a pressure chamber, a pressurized chamber, and a flow path) 6, a fluid resistance portion 7 that also serves as a supply path for supplying ink to the liquid chamber 6, and this fluid A communication portion 8 communicating with the liquid chamber 6 is formed through the resistance portion 7, and ink is supplied from the common liquid chamber 10 formed in the frame member 17 described later through the supply port 9 formed in the diaphragm member 2 in the communication portion 8. Supply.

  The flow path plate 1 is configured by bonding a flow path plate 1A and a communication plate 1B. The flow path plate 1 is formed by etching the SUS substrate with an acidic etchant or machining such as punching (pressing) to open openings such as the communication path 5, the pressurized liquid chamber 6, and the fluid resistance portion 7. Each is formed.

  The diaphragm member 2 is formed of the first layer 2A and the second layer 2B, the first layer 2A forms a thin portion, and the first layer 2A and the second layer 2B form a thick portion. . And this diaphragm member 2 has each vibration field (diaphragm part) 2a formed in the 1st layer 2A which forms the wall surface corresponding to each liquid room 6, and in this vibration field 2a, An island-shaped convex portion 2b formed by the thick portions of the first layer 2A and the second layer 2B is provided on the outer surface (the side opposite to the liquid chamber 6), and the island portion 20 and the island-shaped convex portion 2b vibrate. A piezoelectric actuator 100 including an electromechanical transducer as a driving means (actuator means, pressure generating means) for deforming the region 2a is disposed.

  The piezoelectric actuator 100 includes a plurality of (here, two) laminated piezoelectric members 12 that are bonded to an adhesive on a base member 13, and the piezoelectric member 12 has one groove 31 processed by half-cut dicing. A required number of piezoelectric columns 12A and 12B are formed in a comb-like shape at a predetermined interval with respect to the piezoelectric member 12. The piezoelectric columns 12A and 12B of the piezoelectric member 12 are the same, but a piezoelectric column that is driven by giving a driving waveform is a driving column 12A, and a piezoelectric column that is used as a simple column without giving a driving waveform is a non-driving column. It is distinguished as 12B. Then, the upper end surface (joint surface) of the drive column 12 </ b> A is joined to the island-shaped convex portion 2 b of the diaphragm member 2.

  Here, the piezoelectric member 12 is obtained by alternately stacking the piezoelectric material layers 21 and the internal electrodes 22A and 22B. The internal electrodes 22A and 22B are respectively substantially perpendicular to the end face, that is, the diaphragm member 2 of the piezoelectric member 12. Pulled out to the side surface (surface along the laminating direction), connected to the end face electrodes (external electrodes) 23, 24 formed on this side surface, and a voltage is applied between the end face electrodes (external electrodes) 23, 24 to form the laminating direction Cause displacement.

  The piezoelectric member 12 is connected to an FPC 15 which is a flexible wiring board as a flexible power supply member (wiring member) for supplying a driving signal to the driving column 12A. Although not shown, the FPC 15 is mounted with a driver IC (drive circuit) that applies a drive waveform to the drive column 12 </ b> A, and is fixed to the base member 13 with a hot melt adhesive 16.

  Here, as described above, the piezoelectric columns 12A and 12B of the piezoelectric member 12 are the same, and the piezoelectric column to be driven by giving a driving waveform is used as the driving column 12A, and a simple column without giving the driving waveform. A non-driving column 12B is used as the non-driving column 12B, and the driving column 12A and the non-driving column 12B are alternately used as shown in FIG. 3, but all the piezoelectric columns are driven as shown in FIG. It can also be set as the normal pitch structure used as the pillar 12A.

  The nozzle plate 3 is formed from a nickel (Ni) metal plate, and is manufactured by an electroforming method (electroforming). In this nozzle plate 3, nozzles 4 having a diameter of 10 to 35 μm are formed corresponding to the respective liquid chambers 6 and bonded to the flow path plate 1 with an adhesive. A water repellent layer is provided on the droplet discharge side surface (surface in the discharge direction: discharge surface or surface opposite to the liquid chamber 6 side) of the nozzle plate 3.

  Further, a frame member 17 formed by injection molding with an epoxy resin or polyphenylene sulfite is joined to the outer peripheral side of the actuator portion composed of the piezoelectric element 12, the base member 13, the FPC 15, and the like. The frame member 17 is formed with the common liquid chamber 10 described above, and further, a supply port for supplying recording liquid from the outside to the common liquid chamber 10 is formed. It is connected to an ink supply source such as a cartridge.

  In the liquid discharge head configured as described above, for example, when driven by a pushing method, a drive pulse voltage of 20 to 50 V is selectively applied to the driving piezoelectric column 12A according to an image recorded from a control unit (not shown). By applying the voltage, the piezoelectric column 12A to which the pulse voltage is applied is displaced to deform the vibration region 2a of the vibration plate member 2 in the direction of the nozzle plate 3, and the liquid chamber 6 changes its volume (volume) in the liquid chamber 6. By pressurizing the liquid, droplets are ejected from the nozzle 4 of the nozzle plate 3. As the liquid droplets are discharged, the pressure in the liquid chamber 6 decreases, and a slight negative pressure is generated in the liquid chamber 6 due to the inertia of the liquid flow at this time. Under this state, when the voltage application to the piezoelectric column 12A is turned off, the diaphragm member 2 returns to the original position and the liquid chamber 6 becomes the original shape, so that further negative pressure is generated. . At this time, the recording liquid is filled from the common liquid chamber 10 into the liquid chamber 6, and droplets are ejected from the nozzles 4 in response to the next drive pulse application.

  In addition to the above-described punching, the liquid discharge head is not limited to the pulling method (a method in which the vibrating plate member 2 is released from the pulled state and pressurized with a restoring force), and the pulling-pushing method (the vibrating plate member 2 is fixed). It can also be driven by a method such as a method of holding at an intermediate position, pulling from this position, and then extruding.

Here, the manufacturing method by electroforming of the diaphragm member 2 will be described with reference to FIG. FIG. 5 is an enlarged cross-sectional explanatory view of an island portion for explaining the manufacturing method.
As shown in FIG. 5A, a first layer 142 (thickness 2 μm to 5 μm) for forming a thin portion (diaphragm portion) 2a is formed on the electroformed support substrate 141, and the thickness is as shown in FIG. 5B. By forming a resist pattern 144 in which a portion corresponding to a portion between the meat portions becomes a window and performing, for example, nickel electroforming, nickel is deposited and deposited on the first layer 142 as shown in FIG. When the nickel layer 145 is formed and further electroforming is continued, the nickel layer 145 grows until it protrudes from the window as shown in FIG. As a result, an overhang shape portion is generated.

  If this process is continued, the nickel layer 145 further extends in the thickness direction and the planar direction as shown in FIG. 5E, and after the electroforming is completed at a predetermined growth stage, the pattern is removed. Thus, as shown in FIG. 5F, the diaphragm member 2 having the island-shaped convex portions 2b made of island-shaped thick portions having a bowl-shaped cross section surrounded by the concave portions is obtained. At this time, the island-shaped protrusion 2b has an overhang-shaped portion 145a formed of a nickel layer 145. Here, the formation of the overhang-shaped portion having a thickness of 10 to 20 μm is performed once, but may be repeated twice or more.

Next, the piezoelectric member joined to the diaphragm member will be described with reference to FIG. FIG. 6 is an explanatory front view of the piezoelectric member.
As described above, the piezoelectric member 12 is bonded and fixed to the base member 13 such as SUS430 with an acrylic anaerobic adhesive, and a plurality of piezoelectric columns 12a are used by the grooves 31 (generically used for the driving columns 12A and 12B). Is formed.

  At both ends of these piezoelectric members 12, groove-like step surfaces (step processed portions) 103 </ b> A and 103 </ b> B are provided on the side of the joint surface with the diaphragm member 3. Here, the groove-shaped stepped surface 103A is formed with a groove portion (alignment groove) 104 for alignment with the diaphragm member 2, and the groove-shaped stepped surface 103B has an adhesive application region for applying a temporary adhesive. Become.

Next, the diaphragm member according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 7 is an explanatory plan view as viewed from the piezoelectric member side of the diaphragm member, and FIG. 8 is an enlarged explanatory view showing an alignment pattern portion of the diaphragm member together with a comparative example.
In the diaphragm member 2, island portions 20 are formed corresponding to the respective piezoelectric columns 12 a of the piezoelectric member 12. Then, on both sides of the island region 120 where the island portion 20 is formed, through holes 21 and 21 that are alignment patterns for alignment with the alignment grooves 104 of the piezoelectric member 12 are formed.

  The through hole 21 as the alignment pattern is formed by forming a photoresist pattern at the position of the through hole 21 before forming the first layer 142 in FIG. After forming the first layer 142 and forming the photoresist pattern 144 for forming the second layer 145, the photoresist pattern 144 is similarly formed at the position of the through hole 21. It can be formed by depositing two layers 145.

  Here, both sides of the through holes 21, 21 in the nozzle arrangement direction are formed as the lightening pattern regions 121, and patterns (thickening patterns) 22 having the same shape as the island portions 20 are formed on both sides of the through holes 21. The method of forming the lightening pattern 22 can be formed simultaneously with the island portion 20 at the time of electroforming by providing a photoresist pattern at a required position on the first layer 142 in the same manner as the island portion 20 described above.

  When the diaphragm member 2 configured in this way is joined to the piezoelectric member 12, the alignment groove 104 of the piezoelectric member 12 is imaged by an imaging means such as a CCD camera through the through hole 21 of the diaphragm member 2, and the XY direction is obtained. Adjust the position of. At this time, alignment is performed at two locations of the alignment grooves 104 and 104 at both ends of the piezoelectric member 12 and the diaphragm member 2, and the diaphragm member 2 and the piezoelectric member 12 are highly accurately aligned by the center reference of the parts. Can be joined.

  However, when the diaphragm member 2 is formed by Ni electroforming as described above, there is a difference in current density between the region with the pattern and the region without the pattern, and the region with the pattern is formed relatively thick. Therefore, if there is no thinning pattern 22, the film thickness of the island region 120 is relatively larger than the film thickness of both end regions 121 in the nozzle arrangement direction, and continuously decreases toward both ends.

  Further, as described above, the cross section of the thick portion is an overhang shape portion 145, and as shown in FIG. 8, the position of the through hole 21 is determined by the protruding tip position of the overhang shape portion 145. The protrusion amount is governed by the thickness of the Ni electroformed film.

  Therefore, as in the comparative example shown in FIG. 8A, when there is a difference in film thickness on both sides of the through-hole 21, the overhang shape portions 145a1, 145a2 protrude differently on the left and right, and the overhang shape portions 145a1, 145a2 The distance D2 is wider than the distance D1 when there is no film thickness difference shown in FIG. 4B, and the center position of the through hole 21 is shifted from the target position. For example, if the film thickness difference is 2 μm, the position of the through hole is shifted by 0.5 μm.

  Therefore, by forming the thinning pattern 22 having the same shape as the island portion 20 on both sides of the through holes 21 in the nozzle arrangement direction, as shown in FIG. 8B, the film thickness difference between both sides of the through holes 21 is reduced. Thus, the protruding amounts of the overhanging portions 145a1 and 145a2 are the same on the left and right, and the center position of the through hole 21 can be brought out with high accuracy.

  By providing the center position of the through hole 21 as the alignment pattern with high accuracy, the alignment accuracy with the alignment groove 104 of the piezoelectric member 12 is increased, and the bonding accuracy between the diaphragm member 2 and the piezoelectric member 12 is increased. Can do.

  It should be noted that the lightening pattern 22 is preferably arranged at a symmetrical position with respect to the through hole 21. Thereby, the film thicknesses on both sides of the through hole 21 can be made closer to symmetry.

  In addition, here, five patterns 22 are provided on the inner side (island region 120 side) of the through-hole 21 and 10 points on the outer side (both ends), but 3 to 20 points on the inner side and 5 to 30 on the outer side. There should be only a few places.

  In this way, the center position accuracy of the through hole (alignment pattern) of the diaphragm member can be made high, and the diaphragm member and the piezoelectric member (drive column) can be joined with high precision. . In addition, by providing the lightening pattern, the thickness of the region corresponding to the drive column is made uniform, and further, the film thickness is made uniform up to the region of the diaphragm member corresponding to the temporary adhesive material application region, which is high. Bonding reliability can be obtained.

  Moreover, the protrusion of an adhesive agent can be reduced because the surrounding thick part of the through-hole which is a thinning pattern is formed in an overhang shape.

  As described above, after the piezoelectric member 12 and the diaphragm member 2 are joined, the flow path plate 1 and the nozzle plate 3 are joined to the diaphragm member 2. However, if a through hole is also formed in the flow path plate 1 and the nozzle plate 3 at the position of the alignment through hole 21 in the vibration plate member 2, the vibration plate member 2, the flow path plate 1, and the nozzle plate 3. Can be joined to the piezoelectric member 12 after the first and the second are joined.

Next, a diaphragm member according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 9 is an explanatory plan view seen from the piezoelectric element side of the diaphragm member, and FIG. 10 is an enlarged explanatory diagram showing a positioning pattern portion of the diaphragm member together with a comparative example.
In the present embodiment, the concave portion 23 is formed as the alignment pattern. In order to form the concave portion 23, after forming the first layer 142 in FIG. 5 described above, a photoresist pattern may be formed at the position of the concave portion 23 when the island portion 20 is formed.

  In this way, the photoresist when forming the first layer 142 of the diaphragm member 2 can be reduced, the current density distribution of the first layer 142 can be made uniform, and the thin wall having a uniform thickness can be obtained. The part can be formed. Since the thin-walled portion functions as a deformation region at the time of droplet discharge, the uniformization of the thin-walled portion can suppress variations in ejection characteristics.

An apparatus for joining the diaphragm member 2 and the piezoelectric member 12 will be described with reference to the explanatory view of FIG. In the figure, the diaphragm member shows only the alignment pattern portion.
As shown in FIG. 11A, a piezoelectric member fixing stage 201 for fixing the piezoelectric member 12 and a diaphragm member fixing stage 202 for fixing the diaphragm member 2 are provided. The piezoelectric member 12 and the diaphragm member 2 are fixed to the fixing stages 201 and 202 by vacuum suction, magnetic force, or the like.

  In addition, a piezoelectric member camera 203 and a diaphragm member camera 204 including a CCD camera are provided. The optical axes of these cameras 203 and 204 are aligned using a master work having a through hole before joining. The piezoelectric member fixing stage 201 is movable on the XYZθ axis, and the diaphragm member fixing stage 202 is movable on the XYθ axis (note that the alignment axis direction in FIG. 11 is used when the solid line is shown, but the broken line is not used. It is shown that.). The cameras 203 and 204 are also movable.

  First, as shown in FIG. 11B, the piezoelectric member 12 is fixed to the fixed stage 201. The diaphragm member camera 204 and the diaphragm member fixing stage 202 are retracted forward (illustrated by phantom lines), and the alignment groove 104 of the piezoelectric member 12 is aligned with respect to the piezoelectric member camera 203 in the XYθ axis direction. To do. In addition, if the diaphragm member fixing stage 202 is provided with a through hole, it is not necessary to release it to the front.

  Next, as shown in FIG. 11C, the diaphragm member camera 204 that has been retracted is returned to the original position (the same optical axis position as the piezoelectric member camera 203), and the diaphragm member fixing stage 202 is also moved. Return to the original position. In this state, the concave portion 23 that is the alignment pattern of the diaphragm member 2 is aligned with respect to the diaphragm member camera 204 along the XYθ axes.

  In this state, the piezoelectric member camera 203, the diaphragm member camera 204, the piezoelectric member 12, and the diaphragm member 2 are all aligned. As shown in FIG. The diaphragm member 2 and the piezoelectric member 12 can be joined by moving the piezoelectric member fixing stage 201 in the Z direction after retreating to the front.

  According to this embodiment, when the vibration plate member 2, the flow path plate 1, and the nozzle plate 3 are joined first to form a flow path unit, and then to the piezoelectric member 12, the flow path plate 1 and the nozzle plate. 3 can be joined without providing a through hole at the alignment position of the diaphragm member 2.

  Note that a head-integrated liquid cartridge (cartridge-integrated head) can be obtained by integrating the above-described liquid discharge head and a tank that supplies liquid to the liquid discharge head.

Next, an example of the image forming apparatus according to the present invention including the liquid 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 structure of the mechanism portion of the apparatus, and FIG.
This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held in the main scanning direction by main and slave guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 221A and 221B. The main scanning motor that does not perform moving scanning in the direction indicated by the arrow (carriage main scanning direction) via the timing belt.

  The carriage 233 includes a plurality of recording heads 234 including the liquid discharge head unit according to the present invention for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). Nozzle rows consisting of these nozzles are arranged in the sub-scanning direction orthogonal to the main scanning direction, and are mounted with the ink droplet ejection direction facing downward.

  The recording head 234 is configured by attaching liquid ejection heads 234a and 234b each having two nozzle rows to one base member, and one nozzle row of one head 234a has a black (K) droplet. The other nozzle row ejects cyan (C) droplets, the other nozzle row of the other head 234b ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets. . Note that, here, a two-head configuration is used to eject four color droplets, but a liquid ejection head for each color may be provided.

  The carriage 233 is equipped with sub tanks 235a and 235b (referred to as “sub tank 235” when not distinguished) for supplying ink of each color corresponding to the nozzle rows of the recording head 234. The sub tank 235 is supplied with ink of each color from the ink cartridge 210 of each color by the supply unit 224 via the supply tube 236 of each color.

  On the other hand, as a paper feeding unit for feeding the paper 242 stacked on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feeding) that separates and feeds the paper 242 one by one from the paper stacking unit 241. A separation pad 244 made of a material having a large coefficient of friction is provided opposite to the sheet roller 243 and the sheet feeding roller 243, and the separation pad 244 is urged toward the sheet feeding roller 243 side.

  In order to feed the sheet 242 fed from the sheet feeding unit to the lower side of the recording head 234, a guide member 245 for guiding the sheet 242, a counter roller 246, a conveyance guide member 247, and a tip pressure roller. And a conveying belt 251 which is a conveying means for electrostatically attracting the fed paper 242 and conveying it at a position facing the recording head 234.

  The conveyor belt 251 is an endless belt, and is configured to wrap around the conveyor roller 252 and the tension roller 253 so as to circulate in the belt conveyance direction (sub-scanning direction). In addition, a charging roller 256 that is a charging unit for charging the surface of the transport belt 251 is provided. The charging roller 256 is disposed so as to come into contact with the surface layer of the conveyor belt 251 and to rotate following the rotation of the conveyor belt 251. The transport belt 251 rotates in the belt transport direction when the transport roller 252 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the transport belt 251, a paper discharge roller 262, and a paper discharge roller 263 are provided. A paper discharge tray 203 is provided below the paper discharge roller 262.

  A double-sided unit 271 is detachably attached to the back surface of the apparatus main body. The duplex unit 271 takes in the paper 242 returned by the reverse rotation of the transport belt 251, reverses it, and feeds it again between the counter roller 246 and the transport belt 251. The upper surface of the duplex unit 271 is a manual feed tray 272.

  Further, a maintenance / recovery mechanism 281 for maintaining and recovering the nozzle state of the recording head 234 is disposed in a non-printing area on one side in the scanning direction of the carriage 233. The maintenance / recovery mechanism 281 includes cap members (hereinafter referred to as “caps”) 282a and 282b (hereinafter referred to as “caps 282” when not distinguished) for capping each nozzle surface of the recording head 234, and nozzle surfaces. A wiper blade 283 that is a blade member for wiping the ink, and an empty discharge receiver 284 that receives liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge thickened ink. Yes.

  In addition, in the non-printing area on the other side of the carriage 233 in the scanning direction, idle ejection that receives droplets when performing idle ejection that ejects droplets that do not contribute to recording in order to discharge ink that has been thickened during recording or the like. A receiver 288 is disposed, and the idle discharge receiver 288 is provided with an opening 289 along the nozzle row direction of the recording head 234 and the like.

  In this image forming apparatus configured as described above, the sheets 242 are separated and fed one by one from the sheet feeding tray 202, and the sheet 242 fed substantially vertically upward is guided by the guide 245, and is conveyed to the conveyor belt 251 and the counter. It is sandwiched between the rollers 246 and conveyed, and further, the leading end is guided by the conveying guide 237 and pressed against the conveying belt 251 by the leading end pressing roller 249, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately applied to the charging roller 256, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 251 alternates, that is, in the sub-scanning direction that is the circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width. When the sheet 242 is fed onto the conveyance belt 251 charged alternately with plus and minus, the sheet 242 is attracted to the conveyance belt 251, and the sheet 242 is conveyed in the sub scanning direction by the circumferential movement of the conveyance belt 251.

  Therefore, by driving the recording head 234 according to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 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 242 has reached the recording area, the recording operation is finished and the paper 242 is discharged onto the paper discharge tray 203.

  As described above, since the image forming apparatus includes the liquid discharge head according to the present invention, there is little variation in the droplet discharge characteristics, and a high-quality image can be formed.

Next, another example of the image forming apparatus according to the present invention including the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 14 is a schematic configuration diagram of the entire mechanism section of the apparatus.
This image forming apparatus is a line type image forming apparatus, has an image forming unit 402 and the like inside the apparatus main body 401, and can supply a large number of recording media (sheets) 403 on the lower side of the apparatus main body 401. A paper tray 404 is provided, a sheet 403 fed from the sheet feeding tray 404 is taken in, a required image is recorded by the image forming unit 402 while the sheet 403 is conveyed by the conveying mechanism 405, and then the side of the apparatus main body 401. The paper 403 is discharged to a paper discharge tray 406 attached to the printer.

  Also, a duplex unit 407 that can be attached to and detached from the apparatus main body 401 is provided, and when performing duplex printing, the sheet 403 is conveyed into the duplex unit 407 while being transported in the reverse direction by the transport mechanism 405 after one-side (front) printing is completed. Then, the other side (back side) is sent back to the transport mechanism 405 as the printable side, and the paper 403 is discharged to the paper discharge tray 406 after the other side (back side) printing is completed.

  Here, the image forming unit 402 is, for example, four full-line liquids according to the present invention that discharge droplets of each color of black (K), cyan (C), magenta (M), and yellow (Y). The recording heads 411k, 411c, 411m, and 411y (which are referred to as “recording heads 411” when the colors are not distinguished) are configured with ejection heads. Each recording head 411 has a nozzle surface on which nozzles for ejecting droplets are formed downward. The head holder 413 is attached.

  In addition, a maintenance / recovery mechanism 412k, 412c, 412m, 412y (referred to as “maintenance / recovery mechanism 412” when colors are not distinguished) is provided to maintain and recover the performance of the head corresponding to each recording head 411. During the head performance maintenance operation such as wiping processing, the recording head 411 and the maintenance / recovery mechanism 412 are relatively moved so that the capping member constituting the maintenance / recovery mechanism 412 faces the nozzle surface of the recording head 411.

  Here, the recording head 411 is arranged to eject droplets of each color in the order of blank, cyan, magenta, and yellow from the upstream side in the paper conveyance direction, but the arrangement and the number of colors are not limited to this. Further, as the line type head, one or a plurality of heads provided with a plurality of nozzle rows for discharging droplets of each color at a predetermined interval can be used, or a head and a liquid cartridge for supplying ink to the head are integrated. Or a separate body.

  The paper 403 in the paper feed tray 404 is separated one by one by a paper feed roller (half-moon roller) 421 and a separation pad (not shown) and fed into the apparatus main body 401, and is registered along the guide surface 423 a of the transport guide member 423. It is sent between 425 and the conveyor belt 433, and is sent to the conveyor belt 433 of the conveyor mechanism 405 via the guide member 426 at a predetermined timing.

  In addition, the conveyance guide member 423 is also formed with a guide surface 423 b for guiding the paper 403 sent out from the duplex unit 407. Further, a guide member 427 for guiding the sheet 403 returned from the transport mechanism 405 to the duplex unit 407 during duplex printing is also provided.

  The conveyance mechanism 405 includes an endless conveyance belt 433 that is stretched between a conveyance roller 431 that is a driving roller and a driven roller 432, a charging roller 434 that charges the conveyance belt 433, and an image forming unit 402. A platen member 435 that maintains the flatness of the conveying belt 433 at the opposite portion, a pressing roller 436 that presses the paper 403 fed from the conveying belt 433 against the conveying roller 431 side, and other ink (not shown) that adheres to the conveying belt 433. It has a cleaning roller made of a porous body or the like as a cleaning means for removing.

  On the downstream side of the transport mechanism 405, a paper discharge roller 438 and a spur 439 for sending the paper 403 on which an image is recorded to the paper discharge tray 406 are provided.

  In the image forming apparatus configured as described above, the conveyance belt 433 moves in the direction indicated by the arrow, and is charged by contact with the charging roller 434 to which a high potential application voltage is applied. The conveyance belt is charged to this high potential. When the sheet 403 is fed onto the sheet 433, the sheet 403 is electrostatically attracted to the conveyance belt 433. In this way, the sheet 403 that is strongly adsorbed to the transport belt 433 is calibrated for warpage and unevenness, and forms a highly flat surface.

  Then, the paper 403 is moved around the conveyor belt 433 and droplets are ejected from the recording head 411, whereby a required image is formed on the paper 403, and the paper 403 on which the image has been recorded is the paper discharge roller 438. As a result, the paper is discharged to the paper discharge tray 406.

  As described above, since the image forming apparatus includes the liquid discharge head according to the present invention, there is little variation in the droplet discharge characteristics, and a high-quality image can be formed at high speed.

  In the above-described embodiment, the present invention has been described with reference to an example in which the present invention is applied to an image forming apparatus having a printer configuration. However, the present invention is not limited to this, and may be applied to an image forming apparatus such as a printer / fax / copier multifunction machine. it can. Further, the present invention can be applied to an image forming apparatus using a liquid other than the narrowly defined ink, a fixing processing liquid, or the like.

1 Channel plate (channel substrate)
2 Diaphragm member 2a Diaphragm area (thin part)
2b Island-shaped convex part (thick part)
DESCRIPTION OF SYMBOLS 3 Nozzle plate 4 Nozzle 6 Liquid chamber 10 Common liquid chamber 12 Piezoelectric member 12A Drive pillar 12B Non-drive pillar 12a Piezoelectric pillar 13 Base member 20 Island part 21 Through hole (alignment pattern)
22 Meat removal pattern 23 Recess (Positioning pattern)
104 Alignment groove 233 Carriage 234a, 234b Recording head 411k, 411c, 411m, 411y Recording head

Claims (4)

A deformable diaphragm member that forms at least one wall surface of a liquid chamber through which a plurality of nozzles that discharge droplets communicate with each other;
Driving means for deforming the diaphragm member to pressurize the liquid in the liquid chamber;
The diaphragm member is formed by electroforming,
An island-shaped convex portion formed of a thick-walled portion with which the driving means abuts, and an island portion formed of a thin-walled portion around the island-shaped convex portion;
The island-shaped convex portion has an overhang shape portion,
The diaphragm member is formed with an alignment pattern for alignment with the driving means,
The liquid ejection head, wherein the same pattern as the island portion is formed on both sides of the alignment pattern in the nozzle arrangement direction.   The liquid discharge head according to claim 1, wherein the alignment pattern is a through hole.   The liquid discharge head according to claim 1, wherein the alignment pattern is a concave portion.   An image forming apparatus comprising the liquid discharge head according to claim 1.

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