JP4577045B2 - Liquid jet head - Google Patents

Description

  According to the present invention, a nozzle forming member is bonded to one surface of a flow path forming substrate, and an elastic plate is bonded to the other surface, so that a series of liquid flow paths from a common liquid chamber to a nozzle opening through a pressure chamber are formed. The present invention relates to a liquid ejecting head including a formed flow path unit.

  Examples of the liquid ejecting head that ejects liquid droplets from the nozzle openings by causing pressure fluctuations in the pressure chamber include, for example, an ink jet recording head (hereinafter simply referred to as a recording head) used in an image recording apparatus such as a printer, Color material ejecting heads used for manufacturing color filters such as liquid crystal displays, organic EL (Electro Luminescence) displays, electrode material ejecting heads used for forming electrodes such as FED (surface emitting displays), biochips (biochemical elements) There are bio-organic matter ejecting heads used for manufacturing.

  Taking the case of the above recording head as an example, this recording head includes a nozzle plate having a plurality of nozzle openings, and an empty portion that defines a series of ink flow paths from a common ink chamber to a nozzle opening through a pressure chamber. A flow path forming substrate having a flow path portion such as a groove or a groove, an elastic plate in which a region corresponding to a pressure chamber is elastically deformed according to the operation of a pressure generating element (sealing for sealing an opening surface of the flow path forming substrate) It is configured to include a flow path unit composed of a plate) (for example, see Patent Document 1). Among these flow path unit constituent members, the flow path forming substrate is required to have a high processing density and processing accuracy in order to cope with a high density of recorded images and a high speed recording operation. Therefore, a silicon single crystal substrate (silicon wafer) that can form a fine shape with high dimensional accuracy by anisotropic etching or the like is preferably used as the material of the flow path forming substrate. On the other hand, as a material for the nozzle plate and the elastic plate, for example, a metal plate material such as a stainless steel is used for ease of processing.

  As described above, the flow path forming substrate is provided with a flow path portion such as a through hole (hereinafter simply referred to as a reservoir) serving as a common ink chamber by anisotropic etching or the like. In the head, the end region of the reservoir is formed in a sharp shape that is gradually narrowed toward the end. This is because the ink flow can be made smooth in the end region of the reservoir, and bubbles can be prevented from staying in this region.

Japanese Patent Laid-Open No. 2000-177119 (FIGS. 4, 10, etc.)

  The constituent members of the flow path unit including the nozzle plate, the flow path forming substrate, and the elastic plate are joined by interposing an adhesive between the constituent members and heating and curing the adhesive. However, when the flow path forming substrate is made of silicon and the nozzle plate and the elastic plate are made of a metal plate such as stainless steel, there is a difference in linear expansion coefficient between the base materials of these constituent members. For this reason, a relative expansion / contraction difference may occur due to a temperature change caused by heating and cooling during bonding, and the constituent members may be deformed. At this time, the peripheral edge side of the flow path forming substrate is higher in rigidity than the central side where the flow path portion is provided, and stress concentrates on the boundary portion between the high rigidity area and the low rigidity area. Cracks may occur in the formation substrate. In particular, as in the example of Patent Document 1, when the end region of the reservoir has a sharp shape, since the point is sharp, stress concentrates on the pointed portion. ) Is likely to occur.

  When a crack occurs in a flow path such as a reservoir in this way, ink leaks to the outside of the recording head through the crack, or ink leaked through the crack enters a flow path corresponding to another color and mixes colors. There was a problem that occurred.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid ejecting head capable of preventing cracks from occurring in the liquid flow path of the flow path forming substrate as much as possible. There is to do.

The present invention has been proposed to achieve the above object, and is a flow path forming substrate formed with a crystalline base material and having a flow path portion serving as a liquid flow path. A nozzle forming member having a nozzle opening formed therein, and an elastic plate in which a region corresponding to the pressure chamber is elastically deformed according to the operation of the pressure generating element, and the nozzle is formed on one surface of the flow path forming substrate. A member is provided with a flow path unit that forms a series of liquid flow paths from the common liquid chamber to the nozzle opening by joining the elastic plate to the other surface,
The flow path forming substrate is provided side by side with a dummy flow path portion that is not involved in the discharge of liquid droplets in a state separated from the flow path portion,
The dummy channel portion has a cut portion tapered toward the outside of the flow channel forming substrate at an end portion in a direction perpendicular to the direction in which the dummy flow channel portion is juxtaposed with the flow channel portion. It is provided so that it may be located outside the part.

  According to the above configuration, the portion where the cut portion of the dummy channel portion is formed at the peripheral portion of the channel forming substrate is more fragile than the other portions. When thermal stress is generated due to the change, cracks can be induced in a portion that is preferentially weaker than other portions, starting from the tip of the cut portion. Thereby, the thermal stress at the time of joining can be disperse | distributed and it becomes possible to suppress that a crack arises in the flow-path part side. As a result, it is possible to prevent problems such as the liquid leaking outside the liquid ejecting head or the liquid entering the other flow path portion and mixing the liquid.

  In the above configuration, it is desirable that at least one of the surfaces defining the cut portion is a crack induction surface in which crystals in the flow path forming substrate are set to a crystal orientation plane where the crystals are closest.

  According to this configuration, since the base material having crystallinity tends to break along the closest crystal orientation plane when an external force or impact is applied, at least one of the surfaces defining the cut portion By using a crack induction surface in which the crystal is the closest crystal orientation plane, it is possible to easily induce a crack along the crack induction surface from the tip of the cut portion.

  In this configuration, it is preferable that an auxiliary penetrating portion is provided on the virtual extension line of the crack guiding surface outside the cut portion of the dummy channel portion.

  According to this configuration, when a crack is generated along the crack guiding surface from the tip of the cut portion of the dummy channel portion, the crack can be stopped at the auxiliary penetration portion. Thereby, it is possible to prevent the cracks from being unnecessarily enlarged.

  In the above configuration, the dummy flow path portion is configured to adjust the rigidity of a part of the flow path forming substrate to relieve stress concentration at the time of driving the pressure generating element, or the nozzle on the flow path forming substrate. Desirably, it is a relief hole for introducing excess adhesive or bubbles when joining the forming member and the elastic plate.

  The best mode for carrying out the present invention will be described below with reference to the accompanying 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 following description, an ink jet recording head (hereinafter simply referred to as a recording head) mounted on an ink jet recording apparatus (a type of liquid ejecting apparatus; hereinafter simply referred to as a printer) is taken as an example of the liquid ejecting head of the present invention. To do.

  FIG. 1 is a schematic perspective view of a recording head 1 in the present embodiment, and FIG. The illustrated recording head 1 includes a cartridge base 2 (hereinafter referred to as “base”), a drive substrate 5, a case 10, a flow path unit 11, and an actuator unit 13 as main components. The base 2 is molded from, for example, a synthetic resin such as an epoxy resin, and a plurality of ink introduction needles 4 are attached to the upper surface of the base 2 with a filter 3 interposed therebetween. These ink introduction needles 4 are mounted with ink cartridges (not shown) that store ink (a kind of liquid).

  The drive substrate 5 is provided with a wiring pattern for supplying a drive signal from the printer main body (not shown) to the piezoelectric vibrator 19 and a connector 6 for connection with the printer main body, a resistor, a capacitor, etc. The electronic parts 8 and the like are mounted. A wiring member such as an FFC (flexible flat cable) is connected to the connector 6, and the driving substrate 5 receives a driving signal from the printer main body side via the FFC. The driving substrate 5 is disposed on the bottom surface side of the base 2 opposite to the ink introduction needle 4 with a sheet 7 functioning as a packing interposed.

  The case 10 is a hollow box-shaped member made of synthetic resin, the flow path unit 11 is joined to the front end surface (lower surface), the actuator unit 13 is accommodated in the accommodation space 12 formed inside, The drive substrate 5 is attached to the substrate attachment surface 14 on the side opposite to the flow path unit 11 side. A head cover 16 made of a metal thin plate member is attached to the front end surface side of the case 10 so as to surround the peripheral edge portion from the outside of the flow path unit 11. The head cover 16 functions to protect the flow path unit 11 and the case 10 and adjust the nozzle plate 25 of the flow path unit 11 to the ground potential to prevent troubles such as noise caused by static electricity generated from recording paper or the like. .

  The actuator unit 13 includes a plurality of piezoelectric vibrators 19 (a kind of pressure generating elements) arranged in a comb shape, a fixed plate 20 to which the piezoelectric vibrators 19 are joined, and driving from the driving substrate 5. A wiring member 21 such as a TCP (tape carrier package) for transmitting a signal to the piezoelectric vibrator 19 is formed. Each piezoelectric vibrator 19 has a fixed end portion bonded to the fixed plate 20, and a free end portion protruding outward from the front end surface of the fixed plate 20. That is, each piezoelectric vibrator 19 is mounted on the fixed plate 20 in a so-called cantilever state. The fixing plate 20 that supports each piezoelectric vibrator 19 is made of, for example, stainless steel having a thickness of about 1 mm. The actuator unit 13 is housed and fixed in the housing space 12 by bonding the back surface of the fixed plate 20 to the inner wall surface of the case that defines the housing space 12.

  The flow path unit 11 is manufactured by joining and integrating a flow path unit constituent member made up of an elastic plate 23, a flow path forming substrate 24, and a nozzle plate 25 with an adhesive in a common ink. It is a member that forms a series of ink flow paths (corresponding to the liquid flow paths in the present invention) from the chamber 27 (common liquid chamber) through the ink supply port 28 and the pressure chamber 29 to the nozzle opening 30. The pressure chamber 29 is formed as an elongated chamber in a direction orthogonal to the direction in which the nozzle openings 30 are arranged (nozzle row direction). The common ink chamber 27 is a chamber into which ink from the side of the ink introduction needle 4 inserted into the ink cartridge is introduced. The ink introduced into the common ink chamber 27 is distributed and supplied to each pressure chamber 29 through the ink supply port 28.

  A nozzle plate 25 (a kind of nozzle forming member in the present invention) disposed at the bottom of the flow path unit 11 allows a plurality of nozzle openings 30 to be moved in the paper feed direction (sub-scanning) at a pitch (for example, 180 dpi) corresponding to the dot formation density. It is a thin plate made of metal opened in a row in the direction). The nozzle plate 25 of the present embodiment is made of a stainless steel plate material, and a plurality of rows of nozzle openings 30 (nozzle rows) are arranged in the scanning direction (main scanning direction) of the recording head 1. One nozzle row is composed of, for example, 180 nozzle openings 30. The recording head 1 of the present embodiment is configured to be able to eject a total of four colors of cyan (C), magenta (M), yellow (Y), and black (K), and corresponds to these colors. A total of four nozzle rows are formed on the nozzle plate 25.

  A flow path forming substrate 24 that is one of the flow path unit constituent members is a flow path section 40 that becomes an ink flow path, specifically, an opening 41 that becomes a common ink chamber 27, a groove that becomes an ink supply port 28, And it is the plate-shaped member in which the empty part 42 (all refer FIG. 4) used as the pressure chamber 29 was dividedly formed. In this embodiment, the flow path forming substrate 24 is produced by subjecting a silicon wafer, which is a crystalline base material, to anisotropic etching. Details of the flow path forming substrate 24 will be described later with reference to FIG.

The elastic plate 23 disposed on the surface of the flow path forming substrate 24 opposite to the nozzle plate 25 is a double-structured composite plate material in which an elastic film is laminated on a metal support plate such as stainless steel. An island 32 for joining the tip of the free end of the piezoelectric vibrator 19 is formed at a portion corresponding to the pressure chamber 29 of the elastic plate 23, and this portion functions as a diaphragm portion. That is, the elastic plate 23 is configured such that the elastic film around the island portion 32 is elastically deformed in accordance with the operation of the piezoelectric vibrator 19. In addition, the elastic plate 23 seals one opening surface of the opening 41 of the flow path forming substrate 24 and also functions as a compliance portion 33. A portion corresponding to the compliance portion 33 is made of only an elastic film.
The elastic plate 23 can also be referred to as a sealing plate that seals the opening surface of the flow path portion 40 formed on the flow path forming substrate 24.

  In the recording head 1, when a driving signal is supplied from the driving substrate 5 to the piezoelectric vibrator 19 through the wiring member 21, the piezoelectric vibrator 19 expands and contracts in the longitudinal direction of the element, and accordingly, the island portion 32. Moves in a direction close to or away from the pressure chamber 29. As a result, the volume of the pressure chamber 29 changes, and the pressure in the ink in the pressure chamber 29 changes. An ink droplet (a kind of droplet) is ejected from the nozzle opening 30 by this pressure fluctuation. That is, the piezoelectric vibrator 19 can be said to be a kind of pressure generating source that can cause ink in the pressure chamber 29 to be ejected from the nozzle opening 30 as ink droplets by generating pressure fluctuations in the ink in the pressure chamber 29. .

  FIG. 3 is a plan view of a silicon wafer 35 that is a material of the flow path forming substrate 24. The silicon wafer 35 is, for example, a silicon single crystal substrate whose surface 37 is set to a crystal orientation plane (110) plane. On the surface 37 of the silicon wafer 35, a plurality of substrate regions 24 ′ to be the flow path forming substrate 24 are divided by the planned cutting lines L1 and L2 (10 in this embodiment), and each substrate region 24 ′. The channel portion 40 (see FIG. 4) serving as the ink channel is formed by anisotropic etching. On the planned cutting lines L1 and L2, a plurality of elongated and small through holes are similarly formed by anisotropic etching to form a break pattern. 3 is set on the (110) plane and in the plane direction of the first (111) plane orthogonal to the (110) plane. In addition, a vertical longitudinal cutting line L2 perpendicular to the horizontal cutting line L1 is set in the axial direction perpendicular to the first (111) plane. The first (111) plane constitutes an orientation flat (so-called orientation flat) OF which becomes a reference plane in anisotropic etching.

  FIG. 4 is a plan view illustrating the configuration of the flow path forming substrate 24 obtained by dividing the silicon wafer 35 along the planned cutting lines L1 and L2. As shown in the figure, a flow path portion 40 including an opening 41, an empty portion 42, and the like is formed in the central portion 24a of the flow path forming substrate 24 by anisotropic etching. In the present embodiment, a total of four rows of openings 41 serving as the common ink chambers 27 are formed corresponding to the four colors of ink. From each opening 41, a groove (not shown) serving as the ink supply port 28 and a hollow 42 serving as the pressure chamber 29 are branched into a plurality corresponding to the nozzle openings 30 formed in the nozzle plate 25. Is formed. In the flow path forming substrate 24 of the present embodiment, a total of four sets of flow path portions 40 each including a row of openings 41 and empty portions 42 are formed in a state of being arranged in the main scanning direction. In FIG. 4, the two sets of flow path portions 40 on the left side and the two sets of flow path portions 40 on the right side are paired, and the rows of the empty portions 42 (pressure chamber rows) face each other. Has been placed.

  In addition, a dummy flow path portion 44 that is a through hole that is not involved in the ejection of ink droplets is provided in parallel on the flow path forming substrate 24 in a state of being separated from the flow path portion 40. In the present embodiment, two dummy flow path portions 44 are provided between the pair of flow path portions 40, one in total. More specifically, the dummy flow path portion 44 is disposed between the rows of the empty portions 42 in the adjacent flow path portions 40. Since the dummy flow path portion 44 is provided apart from the flow path portion 40 (that is, in a state not communicating with the flow path portion 40), the dummy flow path portion 44 is normally a portion into which ink does not enter. By adjusting the rigidity of a part of the formation substrate 24, specifically, by intentionally reducing the rigidity between the rows of the empty portions 42, the stress concentration between the rows of the empty portions 42 when the piezoelectric vibrator 19 is driven. It is a part that functions as a buffer hole for relaxing the above. The dummy flow path portion 44 also functions as an escape hole for introducing excess adhesive or bubbles when the flow path unit constituent members are joined, and the adhesive flows into the flow path section 40 side, It prevents the occurrence of poor adhesion due to bubbles entering between the members.

  By the way, both end portions in the sub-scanning direction of the opening 41 are gradually narrowed and pointed toward the end. In this way, the flow of ink at both ends of the opening 41, that is, at both ends of the common ink chamber 27 can be made smooth, and bubbles can be prevented from staying in this portion. However, since the point is sharp, stress concentrates at both ends of the opening 41, so that a crack is easily generated from the tip. If a crack occurs in the flow path section 40 such as the opening 41, ink leaks to the outside of the head through the crack, or the ink leaked through the crack enters the flow path section 40 corresponding to another color. There is a risk of color mixing. In order to solve such a problem, in the flow path forming substrate 24, the shape of the dummy flow path portion 44 is devised, thereby solving the above problem. Hereinafter, this point will be described.

  FIG. 5 is an enlarged view of region A in FIG. The dummy flow path portions 44 in the flow path forming substrate 24 are directed to the outside of the flow path forming substrate 24 at both ends in a direction (sub-scanning direction in the present embodiment) perpendicular to the parallel arrangement direction with the flow path portion 40. It has a notched part 45 that is tapered, and is provided such that a tip T of the notched part 45 is located outside the flow path part 40. In other words, the cut portion 45 is formed with the tip T protruding from the central portion 24a of the flow path forming substrate 24 toward the peripheral edge portion 24b. If it does in this way, in the peripheral part 24b, the part in which this cut | notch part 45 is provided will become weaker than other parts, and will become weak. That is, the notch 45 of the dummy flow path 44 is more likely to crack than both ends of the opening 41.

  Here, the base material having crystallinity such as the silicon wafer 35 which is the base material of the flow path forming substrate 24 of the present embodiment has a crystal orientation plane in which crystals are closest when an external force or impact is applied, That is, it tends to break along the closest surface. This close-packed surface varies depending on the crystal structure of the base material. For example, in the case of a face-centered cubic structure (FCC) like the silicon wafer 35 in the present embodiment, the (111) plane, the body-centered cubic structure (BCC) In the case of (1), the (110) plane is the closest packed plane. In the present embodiment, at least one of the surfaces 45a and 45b that define the notch 45 is set as the closest surface of the flow path forming substrate 24 (silicon wafer 35). Specifically, one surface 45b of the cut portion 45 is set to a second (111) surface that intersects the first (111) surface as an orientation flat at about 70 ° on the (110) surface. . That is, the surface 45b functions as a crack induction surface that actively induces cracks. In this way, by making at least one of the surfaces defining the cut portion 45 as a closest-packed surface (crack induction surface), it is easier to induce a crack along the crack induction surface with the tip of the cut portion 45 as a base point. Can do.

  Further, as shown in FIG. 5, the flow path forming substrate 24 of the present embodiment is outside the cut portion 45 of the dummy flow path portion 44 and on the virtual extension line L of the crack guiding surface (surface 45 b). The auxiliary penetrating portion 46 is provided. Similar to the dummy flow path portion 44, the auxiliary through portion 46 functions as a relief hole for introducing excess adhesive or air bubbles. In this embodiment, the auxiliary through portion 46 is a long and narrow through hole in the main scanning direction. Yes. If this auxiliary penetration part 46 is arranged at the above position, when a crack occurs along the virtual extension line L from the tip of the notch part 45 of the dummy flow path part 44, the progress of the crack is stopped at this auxiliary penetration part 46. be able to. Thereby, it is possible to prevent the cracks from being unnecessarily enlarged.

  As described above, the notch portion in which the dummy flow path portion 44 in the flow path forming substrate 24 is tapered toward the outside of the flow path forming substrate 24 at the end portion in the direction orthogonal to the parallel arrangement direction with the flow path portion 40. 45, and the tip T of the cut portion 45 is provided so as to be located outside of the flow path portion 40, so that the portion where the cut portion 45 is formed in the peripheral edge portion 24b is more than the other portion. Since it becomes fragile, when a thermal stress is generated due to a temperature change at the time of joining the flow path unit constituent members, the crack is preferentially induced in the fragile portion over the other portion with the tip of the cut portion 45 as a base point. be able to. For this reason, the thermal stress at the time of joining can be disperse | distributed and it becomes possible to suppress as much as possible that a crack arises in the flow-path part 40 side. As a result, it is possible to prevent problems such as ink leaking to the outside of the recording head 1 or ink mixing from the flow path portion 40 into another flow path portion 40 to cause color mixing.

  By the way, the present invention is not limited to the above-described embodiment, and various modifications can be made based on the description of the scope of claims.

In the above, an example in which the flow path forming substrate 24 is manufactured using the silicon wafer 35 has been shown. However, the base material of the flow path forming substrate 24 is not limited to the silicon wafer 35 and other base materials having crystallinity. It is also possible to use.
In addition, with respect to the flow path forming substrate 24, the above embodiment has been described with an example in which the flow path forming substrate 24 is configured by a single plate material. That is, for example, a first flow path forming substrate in which a groove portion serving as the ink supply port 28 and a void portion 42 serving as the pressure chamber 29 are formed, and a second flow path formation including an opening portion 41 serving as the common ink chamber 27 are formed. It is also possible to configure the flow path forming substrate 24 with two substrates. In this case, it is desirable that the dummy flow path portion 44 is formed on each substrate, and the tip of the cut portion 45 of the dummy flow path portion 44 is provided outside the flow path portion 40.

  In the above description, the ink jet recording head 1 has been described as an example of the liquid ejecting head, but the present invention can also be applied to other liquid ejecting heads. For example, a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an electrode material ejecting head used for forming an electrode such as an organic EL (Electro Luminescence) display, an FED (surface emitting display), a biochip (biochemical element) The present invention can also be applied to bioorganic matter ejecting heads and the like used in the production of

FIG. 2 is an exploded perspective view illustrating a configuration of a recording head. FIG. 3 is a cross-sectional view of a main part for explaining the configuration of a recording head. It is a top view of the silicon wafer used as the base material of a flow-path formation board | substrate. It is a top view explaining the structure of a flow-path formation board | substrate. It is an enlarged view of the area | region A in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Recording head, 2 Cartridge base, 3 Filter, 4 Ink introduction needle, 5 Driving substrate, 6 Connector, 7 Sheet, 8 Electronic component, 10 Case, 11 Flow path unit, 12 Housing empty part, 13 Actuator unit, 14 Substrate mounting surface, 16 head cover, 19 piezoelectric vibrator, 20 fixing plate, 21 flexible cable, 23 elastic plate, 24 flow path forming substrate, 25 nozzle plate, 27 common ink chamber 28 ink supply port, 29 pressure chamber, 30 nozzle opening , 32 Island part, 35 Silicon wafer, 37 Silicon wafer surface, 40 channel part, 41 opening part, 42 empty part, 44 dummy channel part, 45 notch part, 46 auxiliary penetration part

Claims (4)

Operation of a flow path forming substrate formed of a crystalline substrate and having a flow path portion serving as a liquid flow path, a nozzle forming member having a nozzle opening for discharging droplets, and a pressure generating element The region corresponding to the pressure chamber is configured by an elastic plate that is elastically deformed, and the nozzle forming member is bonded to one surface of the flow path forming substrate, and the elastic plate is bonded to the other surface. A flow path unit that forms a series of liquid flow paths from the liquid chamber through the pressure chamber to the nozzle opening,
The flow path forming substrate is provided side by side with a dummy flow path portion that is not involved in the discharge of liquid droplets in a state separated from the flow path portion,
The dummy channel portion has a cut portion tapered toward the outside of the flow channel forming substrate at an end portion in a direction perpendicular to the direction in which the dummy flow channel portion is juxtaposed with the flow channel portion. Provided to be located outside the part ,
The liquid ejecting head according to claim 1, wherein at least one of the surfaces defining the cut portion is a crack guiding surface in which crystals in the flow path forming substrate are set to a crystal orientation surface where the crystals are closest. 2. The liquid jet according to claim 1, wherein the flow path forming substrate has an auxiliary through portion on a virtual extension line of the crack guiding surface outside the cut portion of the dummy flow path portion. head. The dummy channel portion adjusts the portion of the rigidity of the passage-forming substrate, according to claim 1 or claim characterized in that it is a buffer hole for relieving the stress concentration at the time of the pressure generating element drive 2 liquid jet head according to. The dummy channel section, according claim 1, characterized in that the functions as a relief hole for introducing the excess adhesive or bubbles in bonding the nozzle forming member and the elastic plate in the passage forming substrate Item 4. The liquid jet head according to any one of Items 3 to 4 .

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