JP2014162192A - Liquid discharge head and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge head having sufficient fitting strength with a simple part constitution and in a small number of assembling steps, to which a nozzle cover is attached.SOLUTION: A liquid discharge head includes: a channel unit 100 including a nozzle plate in which nozzles ejecting liquid are formed; a frame member 117 supporting the channel unit 100 and integrally fixing it; a nozzle cover 90 having flexibility and being contacted to and attached to the nozzle plate and the frame member 117. The nozzle cover 90 includes a side wall part 90c contacted to a pair of side surfaces including a long side of a circumference of the nozzle plate of the frame member 117. The side wall part 90c includes an engaging part 90a engaging a recessed groove 117a formed in a side surface of the rame member 117. The engaging part 90a is fitted to the frame member 117 by engaging the engaging part 90a to the recessed groove 117a. A surface of the recessed groove 117a to which the engaging part 90 is contacted has rough surface quality.

Description

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

  As an image forming apparatus such as a printer, a facsimile, a copying apparatus, a plotter, or a complex machine of these, for example, as an image forming apparatus of a liquid discharge recording system using a liquid discharge head (recording head) for discharging ink droplets, an ink jet recording apparatus or the like It has been known.

  This liquid discharge recording type image forming apparatus is a paper (not limited to paper, including an OHP sheet or cloth, on which ink droplets are conveyed from a liquid discharge head, and ink droplets and other liquids can adhere to the paper. Meaning that the recording medium or recording medium (also called recording medium, recording paper, recording paper, etc.) is ejected to form an image (recording, printing, printing, printing is also used synonymously) A serial type image forming apparatus that forms an image by discharging liquid droplets while the liquid discharge head moves in the main scanning direction, or a line that forms an image by discharging liquid droplets without moving the liquid discharge head There is a line type image forming apparatus using a type head.

  In general, a liquid discharge head has a plurality of nozzles (nozzle holes) that discharge liquid as droplets, flow paths such as independent individual liquid chambers that communicate with each nozzle, and energy for pressurizing ink in the individual liquid chambers. Generating pressure generating means. The pressure generation means (actuator means) includes energy generation means including an electromechanical conversion element such as a piezoelectric element or an electrothermal conversion element such as a heater, and is used by driving the element by image information. The liquid can be selectively discharged from the nozzle hole.

  The nozzle plate in which the nozzles in such a liquid ejection head are formed is covered and fixed by a cover member provided with a window portion through which the nozzle opening is exposed. This cover member (hereinafter referred to as “nozzle cover”) is used for the nozzle plate and each member due to external impact (for example, collision of paper conveyed during image formation, wiper member collision during wiping by the wiper member, etc.). To prevent damage.

  In recent years, in order to meet the demand for higher image quality and higher speed, the distance (platen gap) between the nozzle plate surface of the liquid ejection head provided in the image forming apparatus and the paper is reduced to improve the accuracy and stability of image formation. Tend. Since the platen gap is warped or lifted, it is necessary to secure a certain distance. As a method for shortening the platen gap, it is conceivable to reduce the thickness of the nozzle cover.

  On the other hand, since the nozzle cover is required to have high impact resistance, when it is excessively thinned, the rigidity is lowered and the original purpose of protecting the nozzle plate may not be achieved.

  In view of this, a liquid discharge head has been proposed that can reduce the distance between the nozzle opening and the paper while preventing the occurrence of problems due to a decrease in the strength of the nozzle cover (see, for example, Patent Document 1).

  In Patent Document 1, the material of the nozzle cover is made of a metal thin plate material, an inclined shaped fastening ear portion having a fastening hole is formed, and a fastening pin provided on the frame is attached to the frame portion. A configuration is disclosed in which the nozzle cover is attached in a state of being inserted into the fixing hole and pressed against the frame portion.

  The surface of the nozzle plate is generally subjected to water repellent treatment so that it can be easily removed when ink discharged from the nozzle adheres. In this case, it is difficult to fix the contact surface between the nozzle plate and the nozzle cover by bonding. Therefore, a method of fixing the nozzle cover by a method shown in Patent Document 1, a means using a so-called snap-fit configuration, a screw fastening means, or the like is known.

  However, in the case of fastening means using a snap-fit configuration, if the nozzle cover is a thin plate-like metal material (for example, SUS material), it is difficult to secure the mounting strength, and snap-fit is required to realize a strong fastening. When many shape parts are provided, the part shape becomes complicated. In addition, it is necessary to install a positioning hole in the component, and there is a problem that the cost of drilling in the manufacturing process is generated.

  On the other hand, when the screw fastening means is used, there is a problem that the number of parts and the number of assembly steps increase.

  In view of the above problems, an object of the present invention is to provide a liquid discharge head equipped with a nozzle cover having a sufficient mounting strength with a simple component configuration and a small number of assembly steps.

  In order to solve the above-described problems, a liquid discharge head according to the present invention includes a flow path unit including a nozzle plate on which nozzles for discharging liquid droplets are formed, and a frame member that supports the flow path unit and integrally fixes the flow path unit. And at least a nozzle cover that is flexible and is mounted in contact with the frame member, wherein the nozzle cover includes a long side of the outer periphery of the nozzle plate of the frame member. A side wall portion that contacts the side surface of the frame member, an engagement portion that engages with the concave groove formed on the side surface of the frame member on the side wall portion, and the engagement portion is engaged with the concave groove. Thus, the surface of the concave groove that is fitted to the frame member and abuts on the engaging portion has a rough surface property.

  According to the present invention, it is possible to provide a liquid discharge head equipped with a nozzle cover having a sufficient mounting strength with a simple component configuration and a small number of assembly steps.

1 is a perspective view illustrating an example of an appearance of an image forming apparatus according to an embodiment. 1 is a side view illustrating an example of a configuration of an image forming apparatus according to an exemplary embodiment. 1 is a plan view illustrating an example of a main part of an image forming apparatus according to an embodiment. FIG. 6 is a cross-sectional explanatory diagram along the longitudinal direction of the liquid chamber of the liquid discharge head according to the present embodiment. FIG. 5 is an explanatory cross-sectional view along the nozzle arrangement direction of the liquid ejection head according to the present embodiment. FIG. 6 is an external perspective view illustrating an example of a state in which a nozzle cover is attached to the liquid ejection head according to the present embodiment. 3 is an exploded perspective view illustrating an example of a configuration of a liquid ejection head according to the present embodiment. FIG. It is a disassembled perspective explanatory drawing of the flow path unit of the liquid discharge head of this embodiment. It is an exploded side view in the longitudinal direction showing an example of a liquid discharge head according to the present embodiment. It is a side view of the short direction showing an example of a liquid discharge head concerning this embodiment. It is a figure explaining attachment of the nozzle cover of the liquid discharge head concerning this embodiment.

  Hereinafter, a liquid discharge head and an image forming apparatus according to the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the embodiments of the examples shown below, and other embodiments, additions, modifications, deletions, and the like can be changed within a range that can be conceived by those skilled in the art. Any aspect is included in the scope of the present invention as long as the operations and effects of the present invention are exhibited.

The “image forming apparatus” means an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. “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 causing a droplet to land on the medium). ) Also means.
“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 and the like are also included.

[Image forming apparatus]
An example of an image forming apparatus provided with a liquid ejection head according to the present invention is shown in FIG.
FIG. 1 is a perspective explanatory view of the image forming apparatus as viewed from the front side.
The image forming apparatus according to the present embodiment is a liquid discharge head recording apparatus including a liquid discharge head. The apparatus main body 1, a paper feed tray 2 for loading paper mounted on the apparatus main body 1, and the apparatus main body 1 are provided. A paper discharge tray 3 is provided for stocking paper that is detachably mounted and on which images are recorded (formed).
Further, a cartridge loading for loading an ink cartridge that protrudes from the front surface to the front side of the apparatus main body 1 and is lower than the upper surface is provided at one end side of the front surface of the apparatus main body 1 (side of the paper supply / discharge tray section). Part 4. On the upper surface of the cartridge loading unit 4, there is an operation / display unit 5 provided with operation buttons, a display, and the like.

The cartridge loading unit 4 includes a plurality of liquid cartridges 10k and 10c that contain liquids (inks) of different colors, such as black (K) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink, respectively. 10m, 10y (referred to as “liquid cartridge 10” when colors are not distinguished) are loaded.
The liquid cartridge 10 is loaded by being inserted from the front side of the apparatus main body 1 toward the rear side, and a front cover (cartridge cover) 6 that is opened when the liquid cartridge 10 is attached to or detached from the front side of the cartridge loading unit 4. Can be opened and closed.

  Next, the mechanism of the image forming apparatus will be described with reference to FIGS. FIG. 2 is a schematic configuration diagram for explaining the entire configuration of the mechanism unit, and FIG. 3 is a plan view for explaining a main part of the mechanism unit.

  A main guide rod 31 and a sub guide rod 32 that are horizontally mounted on the left and right main side plates 21A and 21B constituting the housing frame 20 hold the carriage 33 slidably in the main scanning direction, and are driven by a main scanning motor (not shown). Moving scanning is performed in the direction of the arrow shown in FIG. 3 (carriage main scanning direction) via the timing belt.

A liquid ejection head 34 according to the present embodiment is mounted on the carriage 33.
In the liquid discharge head 34, a plurality of nozzles that discharge yellow (Y), cyan (C), magenta (M), and black (K) droplets are arranged on the nozzle surface in a direction crossing the main scanning direction. The nozzle rows are mounted with the droplet discharge direction facing downward.

  The liquid discharge head 34 includes pressure generation means for generating pressure for discharging droplets. The pressure generating means includes a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a shape memory alloy actuator that uses a metal phase change caused by a temperature change. An electrostatic actuator using an electrostatic force can be used.

The carriage 33 is mounted with a liquid tank 35 of each color (which may be integrated) for supplying a liquid of each color to the liquid ejection head 34. Each color liquid tank 35 is replenished and supplied with the liquid of each color from the liquid cartridge 10 of each color mounted in the cartridge loading unit 4 via the supply tube 36 having flexibility of each color.
The cartridge loading unit 4 is provided with a supply pump unit 24 that is a liquid feeding means for feeding the liquid in the liquid cartridge 10. The supply tube 36 is held on the front stay 29 by a holding member 37 in the middle.

  As illustrated in FIG. 2, the image forming apparatus 1 serves as a paper feeding unit for feeding the paper 42 stacked on the paper stacking unit (pressure plate) 41 of the paper feeding tray 2, and receives the paper 42 from the paper stacking unit 41. Opposite to the half-moon roller (sheet feeding roller) 43 and the sheet feeding roller 43 which are separated and fed one by one, a separation pad 44 made of a material having a large friction coefficient is provided, and this separation pad 44 is urged toward the sheet feeding roller 43 side. Has been.

  In order to feed the sheet 42 fed from the sheet feeding unit to the lower side of the liquid discharge head 34, a guide member 45 for guiding the sheet 42, a counter roller 46, a conveyance guide member 47, and a tip pressure roller 49. And a conveying belt 51 which is a conveying means for electrostatically adsorbing the fed paper 42 and conveying it to a position facing the liquid ejection head 34.

  The conveyance belt 51 is an endless belt, and is configured to wrap around the conveyance roller 52 and the tension roller 53 and circulate in the belt conveyance direction (sub-scanning direction). Further, a charging roller 56 that is a charging unit for charging the surface of the transport belt 51 is provided.

  The charging roller 56 is disposed so as to come into contact with the surface layer of the transport belt 51 and to rotate following the rotation of the transport belt 51. Further, a guide member 57 serving as a platen portion is disposed on the back side of the conveyance belt 51 so as to correspond to a printing area by the liquid discharge head 34. The conveyance belt 51 rotates in a belt conveyance direction (sub-scanning direction) indicated by an arrow in FIG. 3 when the conveyance roller 52 is rotationally driven through a timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 42 recorded by the liquid discharge head 34, a separation claw 61 for separating the paper 42 from the transport belt 51, a paper discharge roller 62, and a paper discharge roller 63 are provided. In addition, a paper discharge tray 3 is provided below the paper discharge roller 62.

A duplex unit 71 is detachably mounted on the back surface of the apparatus body 1.
The duplex unit 71 takes in the paper 42 returned by the reverse rotation of the transport belt 51, reverses it, and feeds it again between the counter roller 46 and the transport belt 51. The upper surface of the duplex unit 71 is a manual feed tray 72.

  Further, as shown in FIG. 3, a maintenance / recovery mechanism 81 including a recovery means for maintaining and recovering the nozzle state of the liquid ejection head 34 is disposed in the non-printing area on one side of the carriage 33 in the scanning direction. ing.

  The maintenance and recovery mechanism 81 discharges the thickened liquid, a cap member 82 for collectively capping each nozzle of the liquid discharge head 34, a wiper blade 83 which is a blade member for wiping the nozzle surface. Therefore, an empty discharge receiver 84 and the like for receiving droplets when performing empty discharge for discharging droplets that do not contribute to recording are provided.

  The waste liquid of the recording liquid generated by the maintenance / recovery operation by the maintenance / recovery mechanism 81, the liquid discharged to the cap member 82, the liquid adhered to the wiper blade 83 and removed by the wiper cleaner, or the ink ejected idle to the idle ejection receptacle 84 Is discharged and stored in a waste liquid tank (not shown).

  Further, in the non-printing area on the other side in the scanning direction of the carriage 33, the empty discharge for receiving the liquid droplets when performing the empty discharge for discharging the liquid droplets that do not contribute to the recording in order to discharge the thickened liquid during the recording or the like. A receiver 88 is disposed, and the idle discharge receiver 88 is provided with an opening 89 along the nozzle row direction of the liquid discharge head 34 and the like.

  In the image forming apparatus 1 of the present embodiment configured as described above, the sheets 42 are separated and fed one by one from the sheet feed tray 2, and the sheets 42 fed substantially vertically upward are guided by the guide member 45. It is sandwiched between the transport belt 51 and the counter roller 46 and transported. Further, the front end is guided by the transport guide member 47 and pressed against the transport belt 51 by the front end pressure roller 49 to change the transport direction by approximately 90 °. Is done.

  At this time, a charging voltage pattern in which a positive output and a negative output are alternately repeated from the AC bias supply unit of the control unit (not shown) to the charging roller 56, that is, an alternating voltage is applied and the conveying belt 51 alternates. That is, plus and minus are alternately charged in a band shape with a predetermined width in the sub-scanning direction which is the circumferential direction. When the paper 42 is fed onto the conveyance belt 51 charged alternately with plus and minus, the paper 42 is attracted to the conveyance belt 51, and the paper 42 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 51.

  By driving the liquid ejection head 34 according to the image signal while moving the carriage 33, the liquid droplets are ejected onto the stopped paper 42 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 42 has reached the recording area, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.

  While waiting for printing (recording), the carriage 33 is moved to the maintenance / recovery mechanism 81 side, and the discharge surface 34a of the liquid discharge head 34 is capped by the cap member 82, so that the nozzle is kept in a wet state, thereby discharging by liquid drying. Prevent defects. In the state where the ejection surface 34a of the liquid ejection head 34 is capped by the cap member 82, the recording liquid is sucked from the nozzle by a suction pump (not shown) (referred to as “nozzle suction” or “head suction”) to increase the viscosity. Perform a recovery action to drain the liquid. A stable ejection performance of the liquid ejection head 34 can be maintained by performing an idle ejection operation for ejecting a liquid unrelated to the recording before the start of recording or during the recording.

[Liquid discharge head]
The liquid discharge head according to this embodiment includes a nozzle plate on which nozzles for discharging droplets are formed, a flow path plate on which a pressurized liquid chamber communicating with the nozzle is formed, and at least one wall surface of the pressurized liquid chamber A flow path unit composed of a wall surface member, a frame member that supports and fixes the flow path unit, and has flexibility, and can be mounted in contact with the nozzle plate and the frame member. A nozzle cover having flexibility.

  A configuration including the flow path unit and the frame member of the liquid discharge head 34 (hereinafter referred to as “head portion”) will be described with reference to FIGS. 4 and 5. 4 is a cross-sectional view along a direction (liquid chamber longitudinal direction) orthogonal to the nozzle arrangement direction of the head part, and FIG. 5 is a cross-sectional view along the nozzle arrangement direction (liquid chamber short direction) of the head part.

The head portion includes a flow path plate (liquid chamber substrate, flow path substrate) 101 formed of a SUS substrate, a vibration plate member 102 that is a wall surface member bonded to the lower surface of the flow path plate 101, and an upper surface of the flow path plate 101. The flow path unit 100 is composed of a nozzle plate 103 joined to the nozzle plate 103.
The flow path unit 100 includes a plurality of liquid chambers (pressurized liquid chambers, pressure chambers, pressure chambers) as individual flow paths in which a plurality of nozzles 104 that discharge droplets (liquid droplets) communicate with each other via a nozzle communication path 105. 106, also referred to as a pressure chamber or a flow path), a fluid resistance portion 107 that also serves as a supply path for supplying ink to the liquid chamber 106, and a communication portion 108 that communicates with the liquid chamber 106 via the fluid resistance portion 107. doing. Ink is supplied to the communication portion 108 from a common liquid chamber 110 formed in the frame member 117 through a supply port 109 formed in the diaphragm member 102.

The channel plate 101 has a configuration in which a channel plate 101A and a communication plate 101B are bonded.
The flow path plate 101 is formed by opening the nozzle communication path 105, the liquid chamber 106, the fluid resistance portion 107, etc. by etching the SUS substrate using an acidic etching solution or performing machining such as punching (pressing). ing.

  The diaphragm member 102 has each vibration region (diaphragm portion) 102a that forms a wall surface corresponding to each liquid chamber 106, and an island-shaped convex portion on the outer side of the vibration region 102a (on the side opposite to the liquid chamber 106). 102b is provided, and the upper end surface (joint surface) of the piezoelectric element column 112A of the laminated piezoelectric element member 112 as a drive means (actuator means, pressure generating means) for deforming the vibration region 102a is joined to the island-shaped convex portion 102b. doing. Further, the lower end surface of the multilayer piezoelectric element member 112 is joined to the base member 113.

  The piezoelectric element member 112 is formed by alternately laminating piezoelectric material layers 121 and internal electrodes 122 a and 122 b, and the internal electrodes 122 a and 122 b are arranged at respective end surfaces, that is, side surfaces substantially perpendicular to the diaphragm member 102 of the piezoelectric element member 112. Are connected to end face electrodes (external electrodes) 123 and 124 formed on the side surfaces, and a voltage is applied between the end face electrodes (external electrodes) 123 and 124 to cause displacement in the stacking direction.

  The piezoelectric element member 112 is obtained by forming grooves by half-cut dicing and forming a required number of piezoelectric element columns 112A and 112B in a comb shape at a predetermined interval with respect to one piezoelectric element member.

  The piezoelectric element columns 112A and 112B of the piezoelectric element member 112 are the same, but the piezoelectric element column that is driven by giving a driving waveform is used as the piezoelectric element column 112A, and a simple column without giving the driving waveform. The columns are distinguished as piezoelectric element columns 112B.

  In this case, as shown in FIG. 5, the piezoelectric element column 112A for driving and the piezoelectric element column 112B for supporting column are alternately used, but all the piezoelectric element columns are used as the driving piezoelectric element column 112A. A normal pitch configuration can also be used.

  Further, the common external electrodes 124 of all the piezoelectric element columns 112A are electrically connected in common, and the plurality of piezoelectric element columns 112B on one end side of the piezoelectric element member 112 (piezoelectric element array) are arranged on the external electrode 123 side. An FPC 115 as a flexible wiring member is connected to the common external electrode and the individual external electrode 123 of each driving piezoelectric element column 112A as a flexible wiring member by a solder member in order to give a driving signal.

As the nozzle plate 103, one formed from a nickel (Ni) metal plate can be used, for example, one manufactured by an electroforming method (electroforming).
In this nozzle plate 103, nozzles 104 having a diameter of 10 to 35 μm are formed corresponding to the respective liquid chambers 106 and bonded to the flow path plate 101 with an adhesive. A water repellent layer is provided on the droplet discharge side surface (surface in the discharge direction: the discharge surface or the surface opposite to the liquid chamber 106 side) of the nozzle plate 103.

  The liquid discharge head 34 is configured to pressurize the ink in the liquid chamber 106 by using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric element member 112, and the liquid droplet discharge direction is the ink discharge direction in the liquid chamber 106. The liquid droplets are ejected by a side shooter method different from the flow direction.

Further, a frame member 117 is joined to the outer peripheral side of the actuator portion composed of the piezoelectric element member 112, the base member 113, the FPC 115, and the like.
The common liquid chamber 110 described above is formed in the frame member 117, and further, a supply port 119 for supplying ink from the outside to the common liquid chamber 110 is formed. The supply port 119 is connected to an ink supply source such as a sub tank or an ink cartridge (not shown).
The frame member 117 may be a member formed by cutting a metal material, or may be a member formed by injection molding a resin material (such as epoxy resin or polyphenylene sulfite resin).

  In the liquid ejection head 34 configured as described above, for example, when driven by a pushing method, a driving pulse voltage of 20 to 50 V is selected for the driving piezoelectric element column 112A according to an image recorded from a control unit (not shown). As a result, the piezoelectric element column 112A to which the pulse voltage is applied is displaced to deform the vibration region 102a of the vibration plate member 102 in the direction of the nozzle plate 103, and the liquid chamber is changed by the change in volume (volume) of the liquid chamber 106. By pressurizing the ink in 106, droplets are ejected from the nozzles 104 of the nozzle plate 103.

  As the liquid droplets are ejected, the pressure in the liquid chamber 106 decreases, and a slight negative pressure is generated in the liquid chamber 106 due to the inertia of the ink flow at this time. Under this state, the application of voltage to the piezoelectric element column 112A is turned off, so that the diaphragm member 102 returns to the original position and the liquid chamber 106 has the original shape. To do. At this time, ink is filled from the common liquid chamber 110 into the liquid chamber 106, and droplets are ejected from the nozzles 104 in response to the next drive pulse application.

  In addition to the above-described punching, the liquid discharge head 34 has a pulling method (a method in which the vibrating plate member 102 is released from the pulled state and pressurized with a restoring force), and a pulling / pushing method (the vibrating plate member 102). Can be driven by a method such as an extruding method after holding at an intermediate position and pulling it from this position.

FIG. 6 is an external perspective view showing an outline of the configuration of the liquid discharge head of this embodiment, and FIG. 7 is an exploded perspective view. FIG. 8 shows an exploded perspective view of the flow path unit 100.
The liquid discharge head 34 includes the flow path unit 100 and the frame member 117 described in FIGS. 4 and 5 and the nozzle cover 90 that protects the flow path unit 100. The flow path unit 100 includes a nozzle plate 103, a flow path plate 101, and a vibration plate member 102.
The frame member 117 and the flow path unit 100 are fixed, and various parts constituting the flow path unit 100 are bonded by an adhesive or the like.

As shown in FIG. 7, the nozzle cover 90 is a rectangular frame-shaped member, and includes a pair of frame-shaped portions 90 d that contact a pair of short sides on the outer periphery of the nozzle plate 103 and a long side of the outer periphery of the nozzle plate of the frame member 117. The side wall portion 90c has an engaging portion 90a that engages with a concave groove 117a formed on the side surface of the frame member 117.
The nozzle cover 90 is fitted to the frame member 117 by engaging the engaging portion 90a with the concave groove 117a.

  The engaging portion 90a is an edge portion that is bent from the bent edge portion 90b of the side wall portion and protrudes toward the frame member 117 side. The bending angle of the engaging portion 90a and the shape of the tip portion are not particularly limited as long as the engaging portion 90a can be engaged with the concave groove 117a.

  The nozzle cover 90 is integrally formed from a thin plate made of metal (for example, SUS) by pressing or the like. For this reason, there is a problem that the rigidity of the nozzle cover 90 itself cannot be obtained, but by forming the engaging portion 90a bent inward from the bent edge 90b over almost the entire side wall portion 90c, the longitudinal direction Can be ensured.

  For example, the end edge on the opposite side (upper side in the drawing) where the engagement portion 90a is formed may be bent outward to form a flange. Thereby, the rigidity in the longitudinal direction can be further improved, and the workability when the nozzle cover 90 is attached to the head portion can be improved.

  FIG. 9 shows a side view of the head portion and the nozzle cover 90 of the liquid discharge head of this embodiment as seen from the longitudinal direction, and FIG. 10 shows a side view of the head portion as seen from the short direction.

As shown in FIG. 9, the concave groove 117 a is formed from one end of the side surface of the frame member 117 to the other end in parallel with the long side of the outer periphery of the nozzle plate 103.
The engaging portion 90a of the head cover functions as a locking member by being inserted into the concave groove 117a, whereby the nozzle cover 90 is fitted to the frame member 117. In addition, the adhesion of the nozzle cover frame-shaped portion 90d to the nozzle plate 103 is improved, and sufficient attachment strength is obtained. As described above, the engagement portion 90a which is a part of the integrally formed nozzle cover 90 can improve the rigidity of the nozzle cover 90 and the attachment strength to the head portion. And increase in assembly man-hours can be avoided.

In this embodiment, the surface of the concave groove 117a with which the engaging portion 90a of the head cover abuts has a rough surface property.
The surface of the concave groove 117a with which the engaging portion 90a of the head cover abuts is a rougher surface property than the region other than the concave groove 117a on the side surface of the frame member 117, and the side surface of the frame member 117 where the concave groove 117a is formed. The surface is finished more smoothly than the concave groove 117a.
Here, the “rough surface property” means that the value of arithmetic average roughness (Ra), which is a parameter representing the surface roughness, is large, specifically, a surface having fine irregularities. means.

As shown in FIG. 10, the concave groove 117a has a bottom surface 117b that faces the opening surface, and a side surface 117c that intersects the bottom surface 117b. The surface of the concave groove 117a with which the engaging portion 90a of the head cover abuts is the bottom surface 117b and It is at least one of the side surfaces 117c.
Since the surface texture of at least one of the bottom surface 117b and the side surface 117c of the concave groove 117a with which the engaging portion 90a of the head cover abuts is rough, it has a high coefficient of friction, and displacement is not easily generated when the nozzle cover 90 is locked. Reliable installation can be realized.
The concave groove 117a may be processed so that the surface properties of all the inner surfaces including the bottom surface 117b and the side surface 117c are rough.

In the case where the frame member 117 is a member formed by cutting a metal material, as a method of roughing the surface property of the surface of the concave groove 117a with which the engaging portion 90a of the head cover abuts, for example, the concave groove 117a using an end mill is used. For example, there is a method of making the machining speed higher than the machining speed of other regions in the frame member 117.
Further, when the frame member 117 is a member formed by injection molding of a resin material, as a method of roughing the surface property of the surface of the concave groove 117a with which the head cover engaging portion 90a abuts, for example, injection molding gold Examples of the method include a method in which a surface corresponding to the surface portion of the concave groove 117a with which the engagement portion 90a of the head cover abuts is formed with a rough surface.

11A to 11C are cross-sectional views illustrating the process of engagement between the frame member 117 and the nozzle cover 90. FIG. FIG. 11 shows an example in which the engaging portion 90a of the head cover contacts the bottom surface 117b of the concave groove 117a, but the same applies to the case of contacting the side surface 117c.
The distance from the bottom surface 117b of the concave groove on one side surface of the frame member 117 to the other bottom surface 117b is represented by P, and the distance from the tip of one engagement portion 90a of the nozzle cover 90 to the tip of the other engagement portion 90a. Is represented by Q (Q1 to Q3).

  FIG. 11A shows a state as a single member before the nozzle cover 90 is attached to the frame member 117. At this time, the relationship between the distance P between the concave groove bottom surfaces and the distance Q1 between the engaging portions is P> Q1.

  FIG. 11B shows a state before the nozzle cover 90 is attached to the frame member 117 and the concave groove 117a and the engaging portion 90a are engaged. The flexible nozzle cover 90 is mounted while being deformed, and the relationship between the distance P between the concave groove bottom surfaces and the distance Q2 between the engaging portions at this time is P <Q2. The relationship with the distance Q1 between the engaging portions shown in FIG. 11A is Q2> Q1.

  FIG. 11C shows a state in which the groove 117a and the engaging portion 90a are engaged, and the nozzle cover 90 is fitted to the frame member 117. At this time, the relationship between the distance P between the bottom surfaces of the concave grooves and the distance Q3 between the engaging portions is P≈Q3. The relationship with the distance Q1 between the engaging parts before mounting shown in FIG. 11A is Q3> Q1. For this reason, a restoring force is generated in the nozzle cover 90 so as to return the distance between the engaging portions to Q1, and a pressing force is applied to the frame member 117.

  Since the nozzle cover 90 is flexible, when the engaging portion 90a is fitted in the concave groove 117a, the engaging portion 90a serves as a spring, and a frame-like portion 90d that contacts the nozzle plate 103 of the nozzle cover 90. The nozzle cover 90 can be guided so as to be pressed further toward the nozzle plate 103 side, so that the nozzle cover 90 is not lifted from the surface of the nozzle plate 103, and the step can be reduced.

  Furthermore, since the surface property of the concave groove bottom portion 117b with which the engaging portion 90a abuts is rough, a large frictional force is generated by a high friction coefficient and the above-mentioned pressing force, and a high mounting strength between the nozzle cover 90 and the frame member 117 is obtained. .

As described above, the groove 117a is formed in the frame member 117 that holds the nozzle plate 103, and the engaging portion 90a of the nozzle cover 90 is formed at a position corresponding to the groove 117a. Since the opposing bottom surface 117b has a rougher surface property than other portions, the engagement portion 90a engages with the concave groove 117a, so that the nozzle cover 90 is mounted with sufficient attachment strength.
Since the nozzle cover 90 is made of a flexible thin plate material, it is not necessary to increase the platen gap. Moreover, since it consists of a simple fitting configuration, parts manufacturing and assembly operations are not complicated, and the assembly can be performed with simple equipment, so that the cost can be reduced.

DESCRIPTION OF SYMBOLS 1 Image recording device 34 Liquid discharge head 90 Nozzle cover 90a Engagement part 90b Bending edge part 90c Side wall part 90d Frame-like part 100 Channel unit 101 Channel plate 102 Vibration plate member 103 Nozzle plate 117 Frame member 117a Concave groove

JP 2007-062357 A

Claims (7)

A flow path unit including a nozzle plate on which nozzles for discharging droplets are formed;
A frame member that supports and integrally fixes the flow path unit;
A nozzle cover that has flexibility and is mounted in contact with the nozzle plate and the frame member;
The nozzle cover has a side wall portion that contacts a pair of side surfaces including a long side of the outer periphery of the nozzle plate of the frame member, and engages with a concave groove formed on the side surface of the frame member. Having a mating portion, and by engaging the engaging portion with the concave groove, is fitted to the frame member;
The liquid discharge head according to claim 1, wherein a surface of the concave groove with which the engaging portion abuts has a rough surface property.   2. The liquid according to claim 1, wherein a surface of the concave groove with which the engaging portion abuts is at least one of a bottom surface facing the opening surface of the concave groove and a side surface intersecting with the bottom surface. Discharge head.   3. The liquid ejection head according to claim 1, wherein the surface of the groove that the engaging portion contacts has a rougher surface property than a region other than the groove on the side surface of the frame member.   The said recessed groove is formed from the one end part of the side surface of the said frame member to the other end part in the direction along the long side of the said nozzle plate outer periphery, Any one of Claim 1 to 3 characterized by the above-mentioned. A liquid discharge head according to claim 1.   The liquid discharge head according to claim 1, wherein the frame member is formed by injection molding or cutting.   The liquid discharge head according to claim 1, wherein the nozzle cover is integrally formed from a thin metal plate.   An image forming apparatus comprising the liquid discharge head according to claim 1.