JP2009214510A - Liquid jet head and liquid jet apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jet head capable of suppressing temperature rise in a nozzle forming substrate and to provide a liquid jet apparatus having the same. <P>SOLUTION: A metal head cover 40 is attached on a head case 37 so as to cover an edge of a nozzle forming substrate and to expose nozzle openings, has a frame part 59 which, in an attached state on the head case, overlaps on a part of a surface of the nozzle forming substrate, and a side plate part 60 arranged at the side of the head case, and a bellows part 64 is formed by bending a plurality of positions of the side plate part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head such as an ink jet recording head and a liquid ejecting apparatus, and more particularly to a liquid ejecting head and a liquid ejecting apparatus capable of releasing heat from a nozzle forming substrate.

  For example, a liquid ejecting apparatus is an apparatus that includes a liquid ejecting head capable of ejecting liquid and ejects various liquids from the liquid ejecting head. As a typical example of this liquid ejecting apparatus, for example, an ink jet recording head (hereinafter simply referred to as a recording head) as a liquid ejecting head is provided, and liquid ink is recorded on recording paper or the like from a nozzle opening of the recording head. An image recording apparatus such as an ink jet printer that records an image or the like by ejecting and landing on a medium (a target to be ejected) to form dots can be given. In recent years, liquid ejecting apparatuses have been applied not only to this image recording apparatus but also to various manufacturing apparatuses such as a manufacturing apparatus for color filters such as liquid crystal displays.

  By the way, in the above-described printer, when an image or the like is recorded / printed on a recording medium, in particular, a recording paper, there is a possibility that the recording paper may be distorted or uneven or the recorded image may be blurred due to moisture contained in the ink. In particular, when different colors are mixed due to bleeding, the image quality of the recorded image may be deteriorated. In order to cope with such a problem, a configuration has been proposed in which a heating unit (heat source) for heating the recording paper is provided, and drying of the ink landed on the recording paper is promoted by heating the recording paper by the heating unit (for example, , See Patent Document 1).

JP 2001-287455 A

  However, in the configuration in which the recording paper is heated by the heating means, the temperature of the nozzle forming substrate of the recording head may also rise. Then, as the temperature of the nozzle forming substrate rises, the temperature of the ink near the nozzle opening rises, thereby changing its viscosity. As a result, there is a possibility that the ejection characteristics such as the amount of ink ejected from the nozzle opening and the flying speed may fluctuate.

  Some conventional printers detect the temperature around the recording head and correct the drive signal for driving the pressure generating means based on the detected temperature. The temperature of the ink in the vicinity of the nozzle opening cannot be accurately measured because the means for detecting the ink is provided at a position away from the nozzle opening.

  SUMMARY An advantage of some aspects of the invention is to provide a liquid ejecting head capable of suppressing a temperature rise of a nozzle forming substrate and a liquid ejecting apparatus including the liquid ejecting head. There is.

The liquid jet head of the present invention has been proposed to achieve the above object, and a nozzle forming substrate having a nozzle opening,
A head case to which the nozzle forming substrate is fixed;
A metal head cover that covers the edge of the nozzle forming substrate and that is attached to the head case in a state where the nozzle opening is exposed;
The head cover includes a frame portion that overlaps a part of the surface of the nozzle forming substrate in a state of being attached to the head case, and a side plate portion that is disposed on a side surface of the head case,
The side plate portion is bent at a plurality of locations.

  According to this configuration, the side plate portion of the metal head cover that is attached to the head case in a state where the edge of the nozzle forming substrate is covered and the nozzle opening is exposed is bent at a plurality of locations. The heat transmitted from the nozzle forming substrate can be dissipated over the entire head cover. Thereby, the temperature rise of a nozzle formation board | substrate can be suppressed. As a result, it is possible to suppress a change in the viscosity of the liquid, and thus it is possible to prevent fluctuations in the ejection characteristics of the liquid.

  In the above configuration, it is desirable to set the total length of the side plate portion in a state where it is not bent longer than the height of the side surface of the head case.

Moreover, in the said structure, it is also possible to employ | adopt the structure filled with a heat conductive adhesive between the said nozzle formation board | substrate and the said frame part.
The “thermally conductive adhesive” means, for example, an adhesive that includes metal particles or the like and has improved thermal conductivity.

  According to this configuration, since the gap between the nozzle forming substrate and the frame portion can be filled with the heat conductive adhesive, the heat of the nozzle forming substrate can be efficiently transmitted to the head cover, and thereby heat dissipation. The effect can be improved.

  Furthermore, it is also possible to employ a configuration in which a heat conductive adhesive is filled between the side surface of the head case and the side plate portion.

  According to this configuration, by filling the heat conductive adhesive between the side surface of the head case and the side plate portion, the heat of the nozzle forming substrate can be efficiently transmitted to the head cover, and the side surface of the head case It is possible to prevent liquid from entering between the side plate portions. Further, it is possible to prevent the side plate portion from rattling.

And the liquid ejecting apparatus of the present invention includes a liquid ejecting head having the above-described configuration,
Heating means for heating the injection target,
Liquid is ejected from the liquid ejecting head onto the ejected object heated by the heating means.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to these embodiments. In the present embodiment, an image recording apparatus which is one form of the liquid ejecting apparatus, specifically, a length corresponding to the maximum recording width of recording paper as the ejection target (or recording medium) with nozzle aperture groups at equal interval pitches. An ink jet printer (hereinafter simply referred to as a printer) equipped with a long line type liquid ejecting head (hereinafter referred to as a line head) arranged as an example will be described as an example.

  FIG. 1 is a partially broken perspective view illustrating a schematic configuration of a printer 1 according to the present invention. The printer 1 according to this embodiment includes a line head 3 (broadly defined liquid ejecting head) configured by arranging a plurality of head units 11 (narrowly defined liquid ejecting heads) in a staggered manner inside a housing 2, and a recording. A paper feed tray 5 for storing the paper 4 in a stacked state, and a paper feed unit 6 that feeds the recording paper 4 one by one from the paper feed tray 5 and supplies it to the downstream side (conveying unit 7 side) of the line head 3. , A transport unit 7 that transports the recording paper 4 supplied by the paper feeding unit 6 to a recording position, and a drying assist that heats the recording surface of the recording paper 4 on which recording has been performed by the line head 3 to promote ink drying. A portion 8 (a kind of heating means in the present invention), a discharge portion 9 for discharging the recording paper 4 recorded by the line head 3, and a discharge tray 10 for holding the recording paper 4 discharged from the discharge portion 9. And scanning the line head 3 Is configured as the entire width of the recording area of Rukoto without recording paper 4 can be recorded text, an image, or the like.

  Although not shown, an ink cartridge (a type of liquid supply source) that stores ink (a type of liquid in the present invention) is disposed inside the housing 2. The ink stored in the ink cartridge is supplied (pressure-fed) to each head unit 11 of the line head 3 through the ink supply tube by pressurizing the ink cartridge by an air pump or the like.

  In the housing 2, a recording position that is an area above the transport unit 7 and in which the line head 3 ejects ink to record (print) an image or the like on the recording paper 4, and the line head 3. A standby position (home position) is set in which when the camera does not record, it waits out of the recording position. The line head 3 is movably supported by a guide shaft 12 extending over the recording position and the standby position, and moves forward and backward along the guide shaft 12 between the standby position and the recording position. It is configured.

  At the standby position, a capping mechanism 15 having a cap 14 for sealing the nozzle formation surface (nozzle formation substrate 35; see FIG. 2 and the like) of each head unit 11 of the line head 3 is disposed. The capping mechanism 15 has a plurality of tray-like caps 14 made of an elastic member such as an elastomer corresponding to each head unit 11 of the line head 3. Then, the capping mechanism 15 advances (rises) toward each nozzle formation surface of the line head 3 that has moved to the standby position, and seals each cap 14 against the nozzle formation surface of the corresponding head unit 11 by pressing. Stop. By sealing the nozzle forming surface with the cap 14, it is possible to prevent the ink solvent from evaporating from the nozzle openings 33 (see FIG. 2 and the like) and to suppress the thickening of the ink.

  The paper feed unit 6 includes a pickup roller 16, a pair of upper and lower feed rollers 17 a and 17 b, and an endless feed belt 20 that is stretched over a drive roller 18 and a driven roller 19. A pickup roller 16 that is rotationally driven by a motor (not shown) rotates in contact with the uppermost one of the recording paper 4 set in the paper feeding tray 5, thereby removing the uppermost recording paper 4 from the paper feeding tray 5. Pull out. The feeding rollers 17a and 17b feed the uppermost recording paper 4 fed from the paper feeding tray 5 to the feeding belt 20 one by one in a nipped state. The driving roller 18 is rotated by a rotation driving source (not shown) to drive the feeding belt 20 and to feed the recording paper 4 placed on the feeding belt 20 to the conveying unit 7 on the downstream side. It is configured.

  The transport unit 7 includes a transport belt 24 spanned by the transport drive roller 22 and the transport driven roller 23, guide plates 25a and 25b (platens) divided into two on the upstream side and the downstream side, and these guide plates. The heating guide plate 26 is disposed between 25a and 25b and functions as a kind of heating means for heating the recording paper 4 on the transport belt 24 while functioning also as a guide plate. The conveyance drive roller 22 is rotated in synchronization with the recording operation of the line head 3 by a rotation drive source (not shown), thereby driving the endless conveyance belt 24, and the recording paper fed from the paper supply unit 6. 4 is configured to pass below the line head 3 and to be conveyed to the discharge unit 9 side.

  The guide plates 25a and 25b are arranged inside the conveyance belt 24 and support the recording paper 4 on the conveyance belt from the back side of the conveyance belt 24 so as to be parallel to the nozzle formation surface of the line head 3. ing. The heating guide plate 26 is arranged on the inner side of the conveyance belt 24 similarly to the guide plates 25 a and 25 b, and supports the recording paper 4 on the conveyance belt from the back side of the conveyance belt 24. The heating guide plate 26 includes a heat source (not shown), and is configured to heat the recording paper 4 on which the recording operation is performed by the line head 3 from the back side.

  The line head 3 moves from the standby position to the recording position while being guided by the guide shaft 12 when performing the recording operation, stops at this recording position, and makes the nozzle formation surface face the recording paper 4 on the transport belt 24. In this state, the recording paper 4 is configured to perform a recording operation of ejecting ink from the nozzle openings 33. At this time, since the recording paper 4 is heated by the heating guide plate 26, evaporation of the solvent of the ink that has landed on the recording surface of the recording paper 4 is promoted by this heat, thereby shortening the drying time of the ink. Can do.

  The discharge unit 9 includes a discharge belt 30 that is rotated by a rotation drive source (not shown) and a discharge driven roller 29, and a discharge guide plate 31. The discharge drive roller 28 drives the discharge belt 30 by being rotated by a rotation drive source. The discharge belt 30 conveys the recording paper 4 on which an image or the like has been recorded on the recording position side to the downstream side and discharges it to the paper discharge tray 10. Above the discharge belt 30, the drying assist unit 8 is disposed. The drying assist unit 8 is configured to further heat the drying of ink landed on the recording surface of the recording paper 4 by heating the recording paper 4 sent from the recording position side.

  FIG. 2 is a plan view showing the configuration of the line head 3 in the present embodiment, as viewed from the nozzle forming surface side. As shown in the figure, the line head 3 has a plurality of head units 11 arranged in a zigzag pattern in two stages in the direction orthogonal to the conveyance direction of the recording paper 4 (up and down direction in FIG. 2) and attached to the unit holder 34. The nozzle openings 33 of the head unit 11 are arranged in a length that can correspond to the maximum recording width of the recording paper 4 as a whole. The unit holder 34 is movably attached to the guide shaft 12. The unit holder 34 is moved along the guide shaft 12 by a head moving mechanism (not shown), so that the line head 3 is moved between the standby position and the recording position. It has come and goes between.

  FIG. 3 is a cross-sectional view of a main part for explaining the configuration of the head unit 11, FIG. 4 is a plan view of the head unit 11 viewed from the nozzle forming substrate 35, and FIG. 5 shows the head unit 11 in a state attached to the unit holder 34. It is a side view. The head unit 11 includes a head case 37, a vibrator unit 38 housed in the head case 37, a flow path unit 39 joined to the bottom surface (tip surface) of the head case 37, and the flow path unit 39. A metal head cover 40 (see FIGS. 4 and 5) and the like are provided.

  The head case 37 is made of, for example, an epoxy resin, and an accommodation space 41 for accommodating the vibrator unit 38 is formed therein. The vibrator unit 38 includes a piezoelectric vibrator 42 that functions as a kind of pressure generating means, a fixing plate 43 to which the piezoelectric vibrator 42 is joined, and a flexible cable 44 for supplying a drive signal and the like to the piezoelectric vibrator 42. And. The piezoelectric vibrator 42 is a laminated type manufactured by cutting a piezoelectric plate in which piezoelectric layers and electrode layers are alternately laminated into a comb-like shape, and can be expanded and contracted in a direction perpendicular to the lamination direction. This is a piezoelectric vibrator.

  The channel unit 39 is configured by joining a nozzle forming substrate 35 to one surface of the channel forming substrate 45 and a diaphragm 46 to the other surface of the channel forming substrate 45. The flow path unit 39 is provided with a reservoir 47 (liquid chamber), an ink supply port 48, a pressure generation chamber 49, and a nozzle opening 33. A series of ink flow paths (liquid flow paths) from the ink supply port 48 to the nozzle opening 33 through the pressure generation chamber 49 are formed corresponding to each nozzle opening 33.

  The diaphragm 46 has a double structure in which an elastic film 52 is laminated on the surface of the support plate 51. In this embodiment, a stainless plate, which is a kind of metal plate, is used as the support plate 51, and the vibration plate 46 is formed using a composite plate material in which a resin film is laminated on the support plate 51 as an elastic film 52. The diaphragm 46 is provided with a diaphragm 53 that changes the volume of the pressure generating chamber 49. The diaphragm 46 is provided with a compliance portion 54 that seals a part of the reservoir 47.

  The diaphragm 53 is produced by partially removing the support plate 51 by etching or the like. That is, the diaphragm portion 53 includes an island portion 55 to which the distal end surface of the free end portion of the piezoelectric vibrator 42 is joined, and a thin elastic portion around the island portion 55. The compliance portion 54 is produced by removing the support plate 51 in the region facing the opening surface of the reservoir 47 by etching processing or the like in the same manner as the diaphragm portion 53, and reduces the pressure fluctuation of the liquid stored in the reservoir 47. Functions as a damper to absorb.

  Since the tip surface of the piezoelectric vibrator 42 is joined to the island portion 55, the volume of the pressure generating chamber 49 can be changed by expanding and contracting the free end portion of the piezoelectric vibrator 42. As the volume changes, pressure fluctuations occur in the ink in the pressure generating chamber 49. The head unit 11 ejects ink from the nozzle openings 33 using this pressure fluctuation.

  The nozzle forming substrate 35 is made of a metal plate such as stainless steel. As shown in FIGS. 2 and 4, the nozzle formation substrate 35 of each head unit 11 is provided with a plurality of nozzle openings 33 for ejecting ink in a direction orthogonal to the conveyance direction of the recording paper 4. And a plurality of nozzle arrays are formed in the recording paper conveyance direction. One nozzle row in the present embodiment is composed of 180 nozzle openings 33 opened at a pitch of 180 dpi. In the head unit 11, two nozzle rows correspond to each ink type, that is, each ink color. In the present embodiment, it corresponds to four colors of ink, cyan ink (C), magenta ink (M), yellow ink (Y), and black ink (K). Therefore, in this embodiment, a total of 8 nozzle rows are formed side by side in the transport direction. The two nozzle rows of the same color are arranged with their positions relatively shifted in the nozzle row arrangement direction so that the pitch in the nozzle row arrangement direction of the nozzle openings 33 with the adjacent nozzle rows is 360 dpi. Yes. Accordingly, one head unit 11 has a total of 360 nozzle openings 33 arranged in a staggered pattern for each ink color at a pitch of 360 dpi when viewed in a direction orthogonal to the recording sheet conveyance direction (recording sheet width direction).

  As shown in FIG. 2, each head unit 11 is arranged in the unit holder 34 in a two-stage zigzag manner at an arrangement interval such that the nozzle openings 33 are arranged at 360 dpi as a whole when viewed in the direction orthogonal to the recording paper conveyance direction. It is arranged. The number of head units 11 arranged is determined according to the maximum recording width of the recording paper 4.

  Next, the head cover 40 will be described. The head cover 40 is made of a thin metal plate having conductivity, such as stainless steel, like the nozzle forming substrate 35, and covers the outer peripheral edge of the surface (ink ejection side surface) of the nozzle forming substrate 35. This is a member attached to the head case 37 with the nozzle opening 33 exposed.

  The head cover 40 extends along the side surface of the head case 37 from the outer peripheral edge of the frame portion 59 when attached to the head case 37, and a frame-shaped frame portion 59 having an opening window portion 58 formed in the central portion. The four side plate portions 60 are roughly configured. A fastening portion 61 is provided at the tip of each side plate portion 60. A fastening hole 63 through which a fastening pin 62 (fastening member) for attaching to the head case 37 is inserted is formed in the fastening portion 61. The head cover 40 is connected to a ground line (not shown) that leads to the printer body. Accordingly, the nozzle forming substrate 35 is configured to be adjusted to the ground potential through the head cover 40.

  The opening window portion 58 of the head cover 40 has a window frame shape, and the opening dimension (inner dimension) is set slightly smaller than the nozzle forming substrate 35. Therefore, when the head cover 40 is attached to the head case 37, as shown in FIG. Nozzle openings 33 (nozzle rows) are exposed. Thus, since the head cover 40 is attached to the front end side of the head case 37 so as to surround the flow path unit 39 and the nozzle forming substrate 35 from the outside, the recording head 3 is protected from external impacts such as capping and wiping. In addition, the nozzle formation substrate 35 and the head cover 40 are electrically connected to each other, so that the nozzle formation substrate 35 can be adjusted to the ground potential via the head cover 40.

Hereinafter, the heat radiation function that is a feature of the head cover 40 will be described.
FIG. 6 is a plan view of the head cover 40 in a developed state. As described above, the head cover 40 has the four side plate portions 60 extending from the four sides of the frame portion 59. The dimensions of these side plate portions 60 are designed to be as large as possible compared with the side plates of the conventional head cover. For example, the extension length of the side plate portion 60 (the total length when not bent) is set longer than the height of the head case 37. Further, each side plate portion 60 is set with a plurality of planned bending lines BL across the width direction (direction orthogonal to the extending direction) at a plurality of positions in the extending direction at equal intervals. More specifically, a mountain fold planned line and a valley fold planned line are set alternately. And the bellows part 64 is formed as shown in FIG. 5 by bend | folding with the fold planned line BL (mountain fold plan line and valley fold plan line) of each side-plate part 60. As shown in FIG. At this time, the folding angle differs depending on the dimension (extension length) of the side plate portion 60, the number of planned folding lines, and the like. Further, it is not always necessary to bend so as to make a crease, and it may be bent without making a crease so as to have a gentle wave shape.

  The head cover 40 configured as described above has the fixing portion 61 attached to the mounting surface in a state in which the fixing hole 63 is aligned with the female screw portion (not shown) provided on the mounting surface (flange portion) of the head case 37. The frame portion 59 is superimposed on the outer peripheral edge portion of the surface of the nozzle forming substrate 35 on the ink ejection side by inserting the fastening pin 62 into the fastening hole 63 and screwing it into the female screw portion. The side plate portion 60 (the bellows portion 64) is attached to the head case 37 in a state where the side plate portion 60 (the bellows portion 64) is disposed on the side surface side of the head case 37.

  As described above, the size of the side plate portion 60 in the metal head cover 40 is set larger than that of the side plate in the conventional head cover, and the bellows portion 64 is formed by bending at a plurality of locations in the entire length direction of the side plate portion. The heat of the formation substrate 35 can be actively dissipated into the atmosphere. Thereby, the recording paper 4 is heated by the heating unit (the heating guide plate 26 and the drying assist unit 8) so as to promote the drying of the ink that has landed on the recording paper 4, whereby the temperature in the vicinity of the nozzle forming substrate 35 rises. Also in the configuration, the temperature rise of the nozzle forming substrate 35 can be suppressed. As a result, it is possible to suppress the change in the viscosity of the ink around the nozzle opening 33, and thus it is possible to prevent fluctuations in the ink ejection characteristics. And since the bellows part was formed using the head cover provided in the general recording head, it is not necessary to provide a heat radiating means separately. As a result, it is possible to easily impart a heat radiation function to the recording head (line head) while suppressing an increase in cost.

  It should be noted that the dimension of the side plate portion 60 of the head cover 40 is desirably set as large as possible within a range in which the bellows portion 64 does not interfere with the head units 11 or with other structures in the printer. Thereby, the surface area of the side plate part 60 can be increased, and the heat dissipation effect in the bellows part 64 can be improved.

  Further, from the viewpoint of efficiently transferring the heat of the nozzle forming substrate 35 to the head cover 40, a thermally conductive adhesive containing metal particles such as aluminum may be filled between the nozzle forming substrate 35 and the frame portion 59. desirable. Thereby, it becomes possible to further improve the heat dissipation effect. Similarly, the gap (the portion indicated by S in FIG. 5) between the side surface of the head case 37 and the side plate portion 60 (the bellows portion 64) may be filled with a heat conductive adhesive. Thereby, the heat of the nozzle forming substrate 35 can be efficiently transmitted to the head cover 40, and ink is prevented from entering the gap S between the side surface of the head case 37 and the side plate portion 60 (the bellows portion 64). be able to. Further, it is possible to prevent the side plate portion 60 from rattling.

  Further, regarding the heating means, in the above-described embodiment, the heating guide plate 26 that is disposed immediately below the line head 3 and heats the recording paper 4 being recorded, and the drying assist unit 8 that heats the recording surface after the recording is completed. Although illustrated, it is not restricted to this. For example, the present invention is also suitable in a configuration in which preheating means for heating the recording paper 4 in advance before recording by the line head 3 is provided.

  In the above description, the line head 3 mounted on a printer (a kind of liquid ejecting apparatus) is exemplified as the liquid ejecting head according to the present invention. However, the present invention is not limited to other liquid ejecting heads having a metal head cover. Can also be applied. For example, the present invention can be applied to a so-called serial type recording head that ejects ink while reciprocating in the width direction of the recording paper (direction orthogonal to the transport direction). In addition, color material ejection heads used for the production of color filters such as liquid crystal displays, electrode material ejection heads used for electrode formation such as organic EL (Electro Luminescence) displays, FEDs (surface emitting displays), biochips (biochemical elements) The present invention can also be applied to bioorganic matter ejecting heads and the like used in the production of

FIG. 2 is a perspective view illustrating a configuration of a printer. It is a top view which shows the structure of a line head. FIG. 3 is a cross-sectional view of a main part of the recording head. It is the top view which looked at the head unit from the nozzle formation board | substrate side. It is a side view of the head unit in a state attached to the unit holder. It is an expanded view of a head cover.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Printer, 3 ... Line head, 4 ... Recording paper, 8 ... Drying assist part, 11 ... Head unit, 26 ... Heating guide plate, 33 ... Nozzle opening, 34 ... Unit holder, 35 ... Nozzle formation board, 37 ... Head Case: 40 ... Head cover, 58 ... Opening window part, 59 ... Frame part, 60 ... Side plate part, 64 ... Bellows part

Claims (5)

A nozzle forming substrate having a nozzle opening;
A head case to which the nozzle forming substrate is fixed;
A metal head cover that covers the edge of the nozzle forming substrate and that is attached to the head case in a state where the nozzle opening is exposed;
The head cover includes a frame portion that overlaps a part of the surface of the nozzle forming substrate in a state of being attached to the head case, and a side plate portion that is disposed on a side surface of the head case,
A liquid ejecting head, wherein the side plate portion is bent at a plurality of locations.   The liquid ejecting head according to claim 1, wherein an overall length of the side plate portion in a non-bent state is set to be longer than a height of a side surface of the head case.   The liquid jet head according to claim 1, wherein a heat conductive adhesive is filled between the nozzle forming substrate and the frame portion.   The liquid ejecting head according to claim 1, wherein a heat conductive adhesive is filled between a side surface of the head case and the side plate portion. The liquid jet head according to any one of claims 1 to 4,
Heating means for heating the injection target;
A liquid ejecting apparatus comprising:

Images