JP5310414B2 - Liquid ejection head and image forming apparatus - Google Patents

Description

  The present invention relates to a liquid ejection head and an image forming apparatus, and more particularly to a liquid ejection head that ejects liquid droplets and an image forming apparatus including the head.

  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. As an apparatus, an ink jet recording apparatus or the like 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 “image” is not limited to a two-dimensional image, but also includes an image given to a three-dimensionally formed image, and an image formed by three-dimensionally modeling a solid itself.

  Conventionally, a piezoelectric element as a pressure generating means (actuator means) for generating pressure to pressurize ink that is liquid in a pressure chamber (also referred to as a liquid chamber, an individual liquid chamber, or a pressurizing chamber) as a liquid ejection head In particular, using a laminated piezoelectric element in which piezoelectric layers and internal electrodes are alternately laminated, the elastically deformable diaphragm that forms the wall surface of the liquid chamber is deformed by the displacement of the laminated piezoelectric element in the d33 or d31 direction, A piezoelectric head using a so-called piezoelectric actuator that discharges droplets by changing the indoor volume is known. In this specification, “piezoelectric element” is used as a general term for electromechanical transducer elements.

  By the way, in order to eject smaller droplets at a higher frequency, the size of the pressure chamber tends to be smaller, and in the piezoelectric head, the piezoelectric element is longer than the longitudinal length of the pressure chamber. There may be. In this case, when the diaphragm member is formed by nickel electroforming, the diaphragm member is formed in a three-layer structure so that the displacement of the piezoelectric element is transmitted only to the pressure chamber, thereby increasing the generated pressure and crosstalk. However, if a diaphragm member having a two-layer structure is used, the area where the wall surface of the supply path for supplying ink to the pressure chamber is formed by the thin portion of the diaphragm member increases, and the generated pressure decreases. This causes a problem that the ejection performance of the head is deteriorated.

  Further, when the nozzle density in the direction of arrangement of the pressure chambers is made finer, the width of the thick part of the second-stage diaphragm member becomes narrower in the conventional three-layer diaphragm member by nickel electroforming. Further, it becomes difficult to form another thick portion thereon, resulting in a problem that the yield is reduced. Further, a diaphragm member having a three-layer structure is disadvantageous in terms of cost compared to a diaphragm member having a two-layer structure. In particular, in a structure such as a resin diaphragm member made of a thin film made of resin and a thick film made of metal, it is difficult to make a diaphragm itself having a three-layer structure by a construction method.

  With respect to such a head structure, the pressure generating means is not disposed in the portion facing the liquid supply path, so that the flow path unit is not displaced and the thin film region of the diaphragm is provided in the ink supply path. It is known that the structure is not provided (Patent Document 1). It is also known that the ink supply path passes through the thick part of the vibration plate member by bending the ink supply path (Patent Document 2). The diaphragm is thicker than the diaphragm portion in the vicinity of the ink supply port side and the nozzle opening side of the pressure generating chamber, and is a frame-like thick wall extended to the piezoelectric vibrator side so as to expose the diaphragm portion. There is a configuration in which a portion is formed, and a region facing the frame-like thick portion is an adhesion region with a base (Patent Document 3).

JP 2007-176153 A JP 2007-144706 A Japanese Patent No. 3235635

  However, when the structure is such that the piezoelectric element does not oppose the supply path as disclosed in Patent Document 1 described above, the inactive region where the piezoelectric element is not displaced is particularly the thickness of the diaphragm in the piezoelectric element of the d33 method. There is a problem that the generated pressure in the pressure chamber due to the displacement of the piezoelectric element cannot be made sufficiently high because it faces the meat part.

  Further, when the supply path is bent so that the thin portion of the diaphragm member does not face the supply path as disclosed in Patent Document 2, the structure compliance of the supply path can be reduced, but the pressure chamber is provided. Due to the accuracy in the construction method of the flow path component, an area of the diaphragm thin wall portion on the supply path side of the pressure chamber is generated. In particular, when a flow path structure is formed by etching a silicon substrate, the pressure chamber supply path side has no crystal orientation anisotropy, so the length of the pressure chamber varies greatly, and the variation of the thin portion of the diaphragm member also occurs. There is a problem in that it becomes larger, causing a decrease in ejection performance and variations in head characteristics.

  The present invention has been made in view of the above problems, and an object thereof is to improve discharge performance with a simple configuration.

In order to solve the above problems, the liquid discharge head is
A pressure chamber to which the nozzle communicates;
A supply path for supplying liquid to the pressure chamber;
A diaphragm member comprising a thin part and a thick part, having an island-shaped convex part formed by the thick part in the thin part, and forming a part of the wall surface of the pressure chamber by the thin part; ,
An electromechanical conversion element joined to the island-shaped convex portion of the diaphragm member,
Of the portions of the diaphragm member in the longitudinal direction of the diaphragm member facing the electromechanical conversion element, the width of the end portion in the longitudinal direction formed only by the thin portion of the diaphragm is formed by the island-shaped convex portion. In addition, the width of the entire thin portion including the convex portion of the region joined to the electromechanical conversion element is formed to be narrower.

  Here, the structure compliance by the thin part of the diaphragm member can be made smaller than the liquid compliance of the supply path.

  Further, the supply path is disposed at a position shifted from the center in the width direction of the pressure chamber to the end side, and at least a part of the wall surface of the supply path is formed by a thick part of the diaphragm member. And can.

  In this case, the supply path can be configured to be located at the end of the pressure chamber in the width direction.

  An image forming apparatus according to the present invention includes the liquid ejection head according to the present invention.

  According to the liquid ejection head according to the present invention, the width of the longitudinal end region formed only by the thin portion of the diaphragm among the thin portion longitudinal portions of the diaphragm member facing the electromechanical conversion element is Since the island-shaped convex part is formed and formed to be narrower than the entire width of the thin part including the convex part of the region to be joined to the electromechanical conversion element, the displacement due to the electromechanical conversion element faces the pressure chamber. The thin portion of the diaphragm member at the longitudinal end of the pressure chamber is determined by the length of the island-shaped convex portion of the diaphragm member, the length of the pressure chamber, and the displacement of the joining position. , The structural compliance due to the thin portion of the diaphragm member can be reduced, and the droplet ejection performance can be improved.

  According to the image forming apparatus of the present invention, since the liquid discharge head according to the present invention is provided, the droplet discharge performance is improved, so that a high-quality image can be formed by performing stable droplet discharge.

FIG. 3 is an explanatory cross-sectional view along a direction orthogonal to the nozzle arrangement direction of the liquid ejection head according to the first embodiment of the present invention. FIG. 2 is a cross-sectional explanatory view of a main part in the nozzle arrangement direction along the line XX in FIG. 1. Similarly it is principal part plane explanatory drawing. It is principal part top explanatory drawing of the liquid chamber part with which it uses for description of the detail of the diaphragm member of the embodiment. FIG. 5 is a cross-sectional explanatory view taken along line AA in FIG. 4. FIG. 5 is a cross-sectional explanatory view taken along line BB in FIG. 4. It is principal part plane explanatory drawing of the liquid chamber part with which it uses for description of the detail of the diaphragm member of a comparative example. FIG. 8 is an explanatory cross-sectional view taken along the line CC in FIG. 7. FIG. 8 is a cross-sectional explanatory view taken along the line D-D in FIG. 7. FIG. 10 is an explanatory plan view of a main part of a liquid chamber portion for explaining details of a diaphragm member in a liquid discharge head according to a second embodiment of the present invention. FIG. 10 is an explanatory plan view of a main part of a liquid chamber portion for explaining details of a diaphragm member in a liquid discharge head according to a third embodiment of the present invention. It is explanatory drawing which shows an example of the relationship between structure compliance and droplet discharge speed. 1 is an overall configuration diagram illustrating an example of an image forming apparatus according to the present invention. Similarly it is principal part plane explanatory drawing.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. A first embodiment of a liquid discharge head according to the present invention will be described with reference to FIGS. 1 is a cross-sectional explanatory view taken along a direction orthogonal to the nozzle arrangement direction of the head, FIG. 2 is a main cross-sectional explanatory view taken along the line AA in FIG. 1, and FIG. It is a plane explanatory view.

  The liquid discharge head includes a flow path plate (flow path substrate, liquid chamber substrate) 1, a vibration plate member 2 bonded to the lower surface of the flow path plate 1, and a nozzle plate 3 bonded to the upper surface of the flow path plate 1. And a plurality of nozzles 4 for discharging droplets (liquid droplets) by these, respectively, a plurality of liquid chambers (pressurized liquid chambers, pressure chambers, pressure chambers) as individual flow paths communicating with each other via the nozzle communication passages 5. Also referred to as a pressure chamber, a flow path, etc.) 6, a supply path 7 also serving as a fluid resistance section for supplying ink to the liquid chamber 6, and a communication portion 8 communicating with the liquid chamber 6 through the supply path 7 are formed. Then, ink is supplied from the common liquid chamber 10 formed in the frame member 17 described later to the communication portion 8 through the supply port 9 formed in the diaphragm member 2.

  The flow path plate 1 is formed by, for example, subjecting a single crystal silicon substrate having a crystal plane orientation (110) to anisotropic etching using an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH), so that a nozzle communication path 5 and a liquid chamber 6 are obtained. However, the present invention is not limited to a single crystal silicon substrate, and other stainless steel substrates or photosensitive resins can be used. For example, it can be formed by etching a SUS substrate with an acidic etchant or machining such as punching (press). A space between the liquid chambers 6 of the flow path plate 1 is a liquid chamber interval wall 6A.

  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 vibration region 2a is deformed into the island-shaped convex portion 2b. A piezoelectric actuator 100 including an electromechanical conversion element as a driving means (actuator means, pressure generating means) is arranged.

  The piezoelectric actuator 100 has two laminated piezoelectric members 12 bonded with adhesive on a base member 13, and the piezoelectric member 12 is processed with a groove 31 by half-cut dicing and is required for one piezoelectric member 12. A number of piezoelectric element columns 12A and 12B are formed in a comb shape at a predetermined interval. The piezoelectric element columns 12A and 12B of the piezoelectric member 12 are the same, but the piezoelectric element column that is driven by giving a drive waveform is used as the drive piezoelectric element column 12A, and the piezoelectric element is used as a simple column without giving the drive waveform. The columns are distinguished as non-driving piezoelectric element columns 12B.

  Then, the upper end surface (joint surface) of the drive piezoelectric element column 12 </ b> A is joined to the island-shaped convex portion 2 b of the diaphragm member 2. In this embodiment, the length in the liquid chamber longitudinal direction of the driving piezoelectric element column 12A is longer than the length in the liquid chamber longitudinal direction of the island-shaped convex portion 2b 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. By pulling out to the side surface, connecting to the end face electrodes (external electrodes) 23, 24 formed on the side face, and applying a voltage between the end face electrodes (external electrodes) 23, 24, displacement in the stacking direction occurs. Here, the external electrode 23 is used as an individual external electrode (individual electrode), and the external electrode 24 is used as a common external electrode (common electrode).

  The piezoelectric member 12 is connected to an FPC 15 as a flexible wiring member for giving a driving signal to the driving piezoelectric element column 12A. Although not shown, the FPC 15 includes a driver IC (drive circuit) that gives a drive waveform to the drive piezoelectric element column 12A.

  The nozzle plate 3 is formed from a nickel (Ni) metal plate, and is formed by an electroforming method (electroforming). From a metal such as stainless steel, a resin such as a polyimide resin film, silicon, and a combination thereof. Can also be used. 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 piezoelectric actuator 100 composed of the piezoelectric member 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 19 for supplying ink from the outside to the common liquid chamber 10 is formed. Connected to an ink supply source.

  In the liquid ejection head configured as described above, for example, when driven by a punching method, a drive pulse voltage of 20 to 50 V is selectively applied to the drive piezoelectric element column 12A according to an image recorded from a control unit (not shown). When applied, the driving piezoelectric element 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 is changed by the volume (volume) change of the liquid chamber 6. By pressurizing the liquid inside, 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, by turning off the voltage application to the drive piezoelectric element column 12A, the vibration region 2a of the diaphragm member 2 returns to the original position and the liquid chamber 6 becomes the original shape. Furthermore, 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 ejection head has a pulling method (a method in which the diaphragm 2 is released from the pulled state and pressurized with a restoring force), a pull-pushing method (the diaphragm member 2 is placed in the middle). It can also be driven by a method such as a method of holding it at a position, pulling it from this position and then extruding it.

Next, details of the diaphragm member in this embodiment will be described with reference to FIGS. 4 is an explanatory plan view of the main part of the liquid chamber portion, FIG. 5 is an explanatory sectional view taken along the line AA in FIG. 4, and FIG. 6 is an explanatory sectional view taken along the line BB in FIG.
As described above, when the length of the driving piezoelectric element column 12A in the longitudinal direction of the liquid chamber is longer than the length of the island-shaped convex portion 2b of the diaphragm member 2 in the longitudinal direction of the liquid chamber, the driving piezoelectric element column 12A. In addition, a thin portion (portion formed only by the first layer 2A) is provided in a region facing the driving piezoelectric element column 12A of the diaphragm member 2 so as not to interfere with the thick portion 2c other than the island-shaped convex portion 2b. .

  At this time, in this embodiment, the longitudinal direction formed only by the thin part (first layer 2A) of the diaphragm member 2 among the parts of the diaphragm part 2 in the longitudinal direction of the thin part facing the drive piezoelectric element column 12A. The width L1 of the end region is formed to be narrower than the width L2 of the entire thin wall portion (vibration region 2a) including the convex portion 12b of the region where the island-shaped convex portion 2b is formed and joined to the driving piezoelectric element column 12A. Yes. That is, with respect to the longitudinal direction of the liquid chamber 6, the region of the thin portion (first layer 2A) that does not include the convex portion 2b is larger than the width L2 of the vibration region 2a that includes the island-shaped convex portion 2b of the diaphragm member 2. The width L1 is narrowed.

  Thereby, the area | region of the thin part (1st layer 2A) of the diaphragm member 2 in the liquid chamber 6 can be made small, and structural compliance can be made small.

Here, the diaphragm member of the comparative example will be described with reference to FIGS. 7 is an explanatory plan view of the main part of the liquid chamber portion, FIG. 8 is an explanatory sectional view taken along the line CC in FIG. 7, and FIG. 9 is an explanatory sectional view taken along the line DD in FIG. The reference numerals are the same as in the embodiment.
In this comparative example, the region in the longitudinal direction facing the driving piezoelectric element column 12A of the diaphragm member 2 is also driven by the island-shaped convex portion 2b formed in the region formed only by the thin portion (first layer 2A). It is configured to have the same width as the entire vibration region 2a (thin wall portion) including the convex portion 12b of the region to be joined to the piezoelectric element column 12A.

  In the configuration of this comparative example, the area formed only by the thin portion (first layer 2A) of the diaphragm member 2 at the longitudinal end of the liquid chamber 6 is increased, and the structural compliance is increased. As a result, there arises a problem that the discharge performance is deteriorated.

  In this way, among the portions in the longitudinal direction of the thin portion of the diaphragm member facing the electromechanical transducer, the width of the longitudinal end region formed only by the thin portion of the diaphragm is formed as an island-shaped convex portion. The deformation of the diaphragm member that faces the pressure chamber due to the displacement due to the electromechanical conversion element is made narrower than the entire width of the thin part including the convex part of the region joined to the electromechanical conversion element The area of the thin wall portion of the diaphragm member at the end in the longitudinal direction of the pressure chamber, which is determined by the length of the island-shaped convex portion of the diaphragm member, the length of the pressure chamber, and the displacement of the joining position, can be reduced. The structural compliance by the thin part of the diaphragm member can be reduced, and the droplet discharge performance can be improved.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 10 is an explanatory plan view of a main part of the liquid chamber portion of the liquid discharge head according to the embodiment.
Here, the supply path 7 is disposed at a position shifted from the center in the width direction of the liquid chamber 6 toward the end side, and at least a part of the wall surface of the supply path 7 is formed by the thick part of the diaphragm member 2. . As a result, the area of the thin portion (first layer 2A) of the diaphragm member 2 that forms the wall surface of the supply path 7 can be reduced, and the structural compliance of the supply path 7 can be reduced.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 11 is an explanatory plan view of the main part of the liquid chamber portion of the liquid discharge head according to the embodiment.
Here, the supply path 7 is disposed on the end side which is the position most shifted from the center in the width direction of the liquid chamber 6 to the end side, and at least a part of the wall surface of the supply path 7 is thicker than the diaphragm member 2. It is formed with parts. As a result, the area of the thin portion (first layer 2A) of the diaphragm member 2 that forms the wall surface of the supply path 7 can be reduced, and the structural compliance of the supply path 7 can be reduced. In addition, since one side surface of the connecting portion between the supply path 7 and the liquid chamber 6 is formed without a step, the flow of the liquid is smooth and the bubble discharge property in the liquid chamber is improved.

Here, with reference to FIG. 12, the influence on the droplet discharge speed when the structural compliance by the diaphragm thin wall portion on the supply path 7 side of the liquid chamber 6 changes with respect to the liquid compliance of the supply path will be described. . In FIG. 12, the horizontal axis represents the ratio of structural compliance to liquid compliance.
From this result, it can be seen that when the structural compliance becomes larger than the liquid compliance of the supply path 7, that is, when the structural compliance is larger than “1”, the ejection speed of the liquid droplets is drastically decreased. In order to make the fluctuation of the discharge speed within 10%, the structural compliance needs to be smaller than the liquid compliance. It should be noted that the structural compliance is reduced to less than half of the liquid compliance, preferably about 1/5.

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. 13 is a schematic configuration diagram for explaining the overall configuration of the mechanism section of the apparatus, and FIG. 14 is an explanatory plan view of the main part of the mechanism section.
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 liquid discharge head according to the present invention for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K), and a drive signal to the head. A recording head 234 including a liquid discharge head unit in which an electric circuit board to be supplied and a tank for storing ink to be supplied to the head are integrated is arranged in a sub-scanning direction in which a nozzle row including a plurality of nozzles is orthogonal to the main scanning direction. The ink droplet ejection direction is directed downward.

  The recording head 234 is configured by attaching liquid ejection head units 234a and 234b each having two nozzle rows to one base member, and one of the two nozzle rows of the head 234a is black (K). The other two nozzle rows are cyan (C) droplets, the other two nozzle rows of the other head 234b are magenta (M) droplets, and the other two nozzle rows. Ejects yellow (Y) droplets, respectively. Here, although the four-color droplets are ejected in the two-head configuration, four nozzle rows can be arranged per head, and each of the four colors can be ejected by one head.

  In addition, the tanks 235 a and 245 b of the recording head 234 are supplementarily supplied with ink of each color from the ink cartridge 210 of each color via the supply tube 236 for each color.

  On the other hand, as a paper feed unit for feeding the paper 242 loaded on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feed) that feeds the paper 242 from the paper stacking unit 241 one by one. 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 as a recording head, the droplet discharge performance is improved, so that a high-quality image can be formed by performing stable droplet discharge.

  In the above 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 as described above, for example, an image forming apparatus such as a printer / fax / copier multifunction machine. In addition, the present invention can also be applied to an image forming apparatus using a liquid other than the narrowly defined ink or a fixing processing liquid.

DESCRIPTION OF SYMBOLS 1 Flow path plate 2 Diaphragm member 2A 1st layer 2B 2nd layer 2a Vibration area | region (thin part)
2b Island-like convex part 2c Thick part other than island-like convex part 3 Nozzle plate 4 Nozzle 6 Liquid chamber (pressure chamber)
7 Supply path (fluid resistance part)
DESCRIPTION OF SYMBOLS 8 Communication part 10 Common liquid chamber 12 Piezoelectric member 12A Drive piezoelectric element column 12B Non-drive piezoelectric element column 13 Base member 15 Flexible wiring board 17 Frame member 233 Carriage 234 Recording head (liquid discharge head)

Claims (5)

A nozzle for discharging droplets;
A pressure chamber to which the nozzle communicates;
A supply path for supplying liquid to the pressure chamber;
A diaphragm member comprising a thin part and a thick part, having an island-shaped convex part formed by the thick part in the thin part, and forming a part of the wall surface of the pressure chamber by the thin part; ,
An electromechanical conversion element joined to the island-shaped convex portion of the diaphragm member,
Of the portions of the diaphragm member in the longitudinal direction of the diaphragm member facing the electromechanical conversion element, the width of the end portion in the longitudinal direction formed only by the thin portion of the diaphragm is formed by the island-shaped convex portion. The liquid discharge head is characterized in that it is formed narrower than the entire width of the thin portion including the convex portion of the region joined to the electromechanical conversion element.   The liquid ejection head according to claim 1, wherein the structural compliance by the thin portion of the vibration plate member is smaller than the compliance of the liquid in the supply path.   The supply passage is disposed at a position shifted from the center in the width direction of the pressure chamber toward the end portion, and at least a part of the wall surface of the supply passage is formed by a thick portion of the diaphragm member. The liquid discharge head according to claim 1 or 2.   The liquid ejection head according to claim 3, wherein the supply path is located at an end portion in a width direction of the pressure chamber.   An image forming apparatus comprising the liquid discharge head according to claim 1.

Images