JP2009166335A - Liquid jetting head and liquid jetting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jetting head and a liquid jetting apparatus which can improve durability of a driving circuit and can improve liquid jetting characteristics by efficiently carrying out heat radiation of the driving circuit. <P>SOLUTION: The liquid jetting head includes a head body 10 which is equipped with both pressure generation chambers 21 that communicate with nozzle openings 34 for jetting a liquid, and pressure generating means 40 that make the pressure generation chambers 21 generate pressure change; a flexible printed circuit board 50 to which the driving circuit 60 electrically connected to the pressure generating means 40 of the head body 10 to drive the pressure generating means 40 is mounted; and a sheath member 11 which holds the head body 10 and in which the flexible printed circuit board 50 is enclosed. The driving circuit 60 of the flexible printed circuit board 50 is connected to be thermally conductible to an internal surface of the sheath member 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head and a liquid ejecting apparatus that eject liquid from nozzle openings, and more particularly to an ink jet recording head that ejects ink as liquid.

  A part of the pressure generating chamber communicating with the nozzle opening is constituted by a diaphragm, and the diaphragm is deformed by a piezoelectric element to pressurize ink in the pressure generating chamber and eject ink droplets from the nozzle opening. Has been put to practical use using a flexural deformation of a piezoelectric element comprising a lower electrode, a piezoelectric layer and an upper electrode.

  In addition, a drive circuit for inputting a drive signal for driving the piezoelectric element is mounted on a flexible printed circuit board, and is electrically connected to the piezoelectric element through the flexible printed circuit board (see, for example, Patent Document 1). .

JP 2005-131881 A

  However, since the drive circuit mounted on the flexible printed circuit board can only dissipate heat by the drive circuit itself, the heat dissipation capability is limited. When the circuit loss exceeds the heat dissipation capability, the drive circuit is destroyed by heat. In addition, in order to ensure heat dissipation, a heat dissipation area is required, and thus there is a problem that the drive circuit cannot be reduced in size.

  Such a problem exists not only in an ink jet recording head but also in a liquid ejecting head that ejects liquid other than ink.

  In view of such circumstances, the present invention provides a liquid ejecting head and a liquid ejecting apparatus that can efficiently dissipate heat from the drive circuit, improve the durability of the drive circuit, and improve the liquid ejecting characteristics. The purpose is to do.

An aspect of the present invention that solves the above-described problems includes a head main body that includes a pressure generation chamber that communicates with a nozzle opening that ejects liquid, and a pressure generation unit that causes a pressure change in the pressure generation chamber. A flexible printed circuit board on which a drive circuit that is electrically connected to the pressure generating means and drives the pressure generating means is mounted; and an exterior member that holds the head body and encloses the flexible printed circuit board. In the liquid ejecting head, the driving circuit of the flexible printed circuit board is connected to the inner surface of the exterior member so as to be capable of conducting heat.
In this aspect, the heat of the drive circuit can be dissipated to the atmosphere through the exterior member, so that the drive circuit can be prevented from being destroyed by heat, and the drive circuit does not need to be enlarged and downsized. Cost can be reduced. Further, it is possible to improve the durability by preventing the life of the drive circuit from being shortened due to heat generation, and to improve the liquid ejection characteristics and the continuous ejection performance.

  Here, it is preferable that the exterior member is a member in which a coupling region where the drive circuit is connected to be thermally conductive is higher in heat dissipation than other regions. According to this, the heat dissipation of the drive circuit can be further improved by the coupling region, and only the coupling region is formed of a material having a relatively high heat dissipation, so that the exterior member becomes heavy and used for high-speed movement and movement. It is possible to prevent a burden on the motor and the like. In addition, a material with high heat dissipation often has conductivity, and the occurrence of static electricity or the like can be prevented by grounding the housing.

  Moreover, it is preferable that the said exterior member is a head case provided with the circuit board to which the said flexible printed circuit board is connected. According to this, by using the head case as the exterior member to which the drive circuit is connected so as to be able to conduct heat, a new member becomes unnecessary and the cost can be reduced.

  Further, the head case has a hollow box shape, the flexible printed circuit board is bent along a wall surface in the head case, and the drive circuit and the wall surface of the head case conduct heat. It is preferable that the connection is possible. According to this, the drive circuit and the wall surface of the head case can be connected easily and reliably so as to be able to conduct heat.

  Moreover, it is preferable that the said pressure generation means is a piezoelectric element of a bending vibration mode. According to this, the heat of the drive circuit of the flexible printed circuit board connected to the piezoelectric element in the flexural vibration mode can be efficiently radiated.

  Moreover, it is preferable that the said drive circuit and the said exterior member are adhere | attached through the adhesive agent which has an electrothermal filler. According to this, it is possible to prevent heat conduction from being interrupted due to a gap between the drive circuit and the exterior member when the liquid ejecting head is moved, and to reliably radiate the heat of the drive circuit by the exterior member. Can do.

According to still another aspect of the invention, there is provided a liquid ejecting apparatus including the liquid ejecting head according to the above aspect.
According to this aspect, it is possible to realize a liquid ejecting apparatus with improved reliability and reduced cost.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
FIG. 1 is an exploded perspective view of an ink jet recording head that is an example of a liquid jet head according to Embodiment 1 of the present invention, FIG. 2 is a plan view of the ink jet recording head, and FIG. It is AA 'sectional drawing and BB' sectional drawing.

  As shown in the drawing, an ink jet recording head I of this embodiment includes a head main body 10 that ejects ink, and a flexible print that is electrically connected to the pressure generating means of the head main body 10 and supplies a drive signal to the pressure generating means. A substrate 50 and a head case 11 which is provided on the side opposite to the ink discharge surface of the head body 10 and is an exterior member of the ink jet recording head I are provided.

  First, the head body 10 of this embodiment will be described. As shown in FIG. 3B, the head body 10 includes an actuator unit 20, one flow path unit 30 to which the actuator unit 20 is fixed, and a flexible printed circuit board 50 connected to the actuator unit 20. ing.

  The actuator unit 20 is an actuator device including a piezoelectric element 40, and includes a flow path forming substrate 22 in which a pressure generation chamber 21 is formed, a vibration plate 23 provided on one surface side of the flow path forming substrate 22, And a pressure generation chamber bottom plate 24 provided on the other surface side of the path forming substrate 22.

The flow path forming substrate 22 is made of, for example, a ceramic plate such as alumina (Al ₂ O ₃ ) or zirconia (ZrO ₂ ) having a thickness of about 150 μm. In this embodiment, the plurality of pressure generating chambers 21 have their widths. Two rows arranged in parallel along the direction are formed. A vibration plate 23 made of, for example, a zirconia thin plate having a thickness of 10 μm is fixed to one surface of the flow path forming substrate 22, and one surface of the pressure generating chamber 21 is sealed by the vibration plate 23.

  The pressure generation chamber bottom plate 24 is fixed to the other surface side of the flow path forming substrate 22 to seal the other surface of the pressure generation chamber 21, and is provided in the vicinity of one end of the pressure generation chamber 21 in the longitudinal direction. A supply communication hole 25 that communicates the generation chamber 21 with a reservoir, which will be described later, and a nozzle communication hole 26 that is provided near the other end in the longitudinal direction of the pressure generation chamber 21 and communicates with a nozzle opening 34 that will be described later.

  And the piezoelectric element 40 is provided in each area | region facing each pressure generation chamber 21 on the diaphragm 23. For example, in this embodiment, since the row | line | column of the pressure generation chamber 21 is provided in two rows, it is piezoelectric. Two rows of elements 40 are also provided.

  Here, each piezoelectric element 40 is provided on the lower electrode film 43 provided on the vibration plate 23, the piezoelectric layer 44 provided independently for each pressure generation chamber 21, and the piezoelectric layer 44. And the upper electrode film 45 thus formed. The piezoelectric layer 44 is formed by attaching or printing a green sheet made of a piezoelectric material. The lower electrode film 43 is provided across the piezoelectric layers 44 arranged side by side and serves as a common electrode for the piezoelectric elements 40, and functions as a part of the diaphragm. Of course, the lower electrode film 43 may be provided for each piezoelectric layer 44. Such a piezoelectric element 40 is a so-called flexural vibration mode piezoelectric element 40 that bends and deforms in the thickness direction.

  The flow path forming substrate 22, the vibration plate 23, and the pressure generation chamber bottom plate 24, which are each layer of the actuator unit 20, are formed by molding a clay-like ceramic material, a so-called green sheet, to a predetermined thickness, for example, a pressure generation chamber After drilling 21 and the like, they are laminated and fired to integrate them without requiring an adhesive. Thereafter, the piezoelectric element 40 is formed on the vibration plate 23.

  On the other hand, the flow path unit 30 includes an ink supply port forming substrate 31 joined to the pressure generating chamber bottom plate 24 of the actuator unit 20 and a reservoir forming substrate on which a reservoir 32 serving as a common ink chamber of the plurality of pressure generating chambers 21 is formed. 33 and a nozzle plate 35 in which nozzle openings 34 are formed.

  The ink supply port forming substrate 31 is made of a zirconia thin plate having a thickness of 150 μm, the nozzle communication hole 36 connecting the nozzle opening 34 and the pressure generation chamber 21, and the reservoir 32 and the pressure generation chamber 21 together with the supply communication hole 25 described above. The ink supply port 37 is connected to each other, and an ink introduction port 38 that communicates with each reservoir 32 and supplies ink from an external ink tank is provided.

  The reservoir forming substrate 33 receives a supply of ink from an external ink tank (not shown) on a plate material having corrosion resistance such as 150 μm stainless steel, which is suitable for forming an ink flow path. And a nozzle communication hole 39 for communicating the pressure generating chamber 21 and the nozzle opening 34.

  The nozzle plate 35 is formed, for example, by forming nozzle openings 34 in a thin plate made of stainless steel at the same arrangement pitch as the pressure generating chambers 21. For example, in the present embodiment, since the flow path unit 30 is provided with two rows of the pressure generating chambers 21, the nozzle plate 35 is also formed with two rows of nozzle openings 34. The nozzle plate 35 is bonded to the opposite surface of the flow path forming substrate 22 of the reservoir forming substrate 33 to seal one surface of the reservoir 32.

  Such a flow path unit 30 is formed by fixing the ink supply port forming substrate 31, the reservoir forming substrate 33, and the nozzle plate 35 with an adhesive, a heat welding film, or the like. In the present embodiment, the reservoir forming substrate 33 and the nozzle plate 35 are formed of stainless steel. However, for example, the reservoir forming substrate 33 and the nozzle plate 35 are formed of ceramics, and the flow path unit 30 is integrally formed in the same manner as the actuator unit 20. You can also.

  And such a flow-path unit 30 and the actuator unit 20 are joined and fixed via the adhesive agent and the heat welding film.

  As shown in FIGS. 2 and 3, the region opposite to the peripheral wall of the pressure generation chamber 21 at one longitudinal end of each piezoelectric element 40 is made of gold (Au) or the like connected to the upper electrode film 45. The individual connection terminal 46 is provided. The individual connection terminal 46 is provided for each piezoelectric element 40. In addition, as shown in FIG. 2, common connection terminals 47 made of gold (Au) connected to the lower electrode film 43 are provided on both outer sides of the rows of the piezoelectric elements 40 between the rows of the piezoelectric elements 40 arranged side by side. Is provided. A wiring layer 51 provided on the flexible printed circuit board 50 is electrically connected to the individual connection terminal 46 and the common connection terminal 47 provided on each of the upper electrode film 45 and the lower electrode film 43 of the piezoelectric element 40. A drive signal from the drive circuit 60 is supplied to each piezoelectric element 40 via the flexible printed board 50.

  The flexible printed board 50 is formed of, for example, a flexible printing circuit (FPC), a tape carrier package (TCP), or the like, which is provided over two rows of piezoelectric elements 40. Specifically, the flexible printed circuit board 50 is formed, for example, by forming a wiring layer 51 having a predetermined pattern on a surface of a base film 52 made of polyimide or the like with a thin copper film or the like, and other than the terminal portion connected to the piezoelectric element 40 of the wiring layer 51. The region is covered with an insulating material 53 such as a resist.

  The flexible printed board 50 is connected to one end side piezoelectric element 40 and the other end side is connected to a circuit board 70 to which external wiring to which a print signal or the like is input is connected. The circuit board 70 is provided with a connector to which external wiring is connected and an operation circuit for operating the piezoelectric element 40 is mounted.

  Furthermore, a drive circuit 60 for driving the piezoelectric element 40 is mounted on the wiring layer 51 of the flexible printed board 50. Examples of the drive circuit 60 include a circuit board and a semiconductor integrated circuit (IC). Such a drive circuit 60 is mounted on the wiring layer 51 of the flexible printed board 50 by, for example, flip mounting. The drive circuit 60 is mounted on the flexible printed board 50 by, for example, metal connection such as gold (Au) -gold (Au) connection, gold (Au) -tin (Sn) connection, or ACF (anisotropic). Conductive paste), ACP (anisotropic conductive film), solder bump connection, or the like can be used.

  On the other hand, the head main body 10 is provided with a head case 11 that is an exterior member of the ink jet recording head I of this embodiment.

  The head case 11 includes a base portion 12 that holds a circuit board 70 to which the flexible printed circuit board 50 is connected, and a case portion 13 having a hollow box shape provided on the bottom surface side of the base portion 12.

  The case portion 13 is provided with an opening 14 that exposes the piezoelectric element 40 of the head body 10 while the head body 10 is bonded to the bottom surface. In the present embodiment, the surface of the case body 13 opposite to the nozzle plate 35 of the flow path unit 30 of the head body 10 is bonded to the bottom surface of the case body 13 with an adhesive or the like. And in the case part 13, the flexible printed circuit board 50 electrically connected to the piezoelectric element 40 is included.

  The head case 11 is connected to an ink cartridge, which is a liquid storage means for storing liquid, a tube member connected to the ink tank, and the like, and supplies ink to the head main body 10 held on the bottom surface of the case portion 13. A liquid supply path 15 is provided.

  The base portion 12 is formed integrally with the case portion 13 so as to protrude outward from the side surface of the case portion 13, and the circuit board 70 is held in the protruding region. The base portion 12 may be designed with a configuration that holds the circuit board 70 in the vertical direction.

  The flexible printed board 50 enclosed in the case portion 13 is bent along the wall surface of the case portion 13 and is electrically connected to the circuit board 70 of the base portion 12.

  Such a flexible printed circuit board 50 is disposed such that the surface on which the drive circuit 60 is provided is opposed to the inner wall surface of the head case 11, and the drive circuit 60 is thermally conductive to the inner surface of the head case 11. Possible connection, ie thermal coupling. In the present embodiment, the drive circuit 60 is thermally coupled to the side surface that is the wall surface of the case portion 13 of the head case 11. Here, the state in which the drive circuit 60 and the head case 11 are thermally coupled (connected so as to allow heat conduction) refers to a state in which they are in contact with each other or a state in which both are bonded to each other via an adhesive or the like. To tell. That is, the drive circuit 60 and the head case 11 may be in contact with each other or may be joined with an adhesive or the like.

  When the drive circuit 60 and the wall surface of the head case 11 are brought into contact with each other, for example, a biasing means such as a spring or rubber that biases the drive circuit 60 toward the inner wall surface of the head case 11, a clip, or the like It is sufficient that the contact state by the fixing means is not released. Further, when the drive circuit 60 and the inner surface of the head case 11 are joined via an adhesive, it is preferable to use a material having a relatively high thermal conductivity as the adhesive. Examples of the adhesive having a high thermal conductivity include an adhesive in which an electrothermal filler made of a silicone material is kneaded. In this embodiment, as shown in FIG. 3, the drive circuit 60 and the head case 11 are joined via the adhesive 16. As a result, when the ink jet recording head I is mounted on the carriage and moved in the main scanning direction, a gap is generated between the drive circuit 60 and the head case 11 due to the movement of the carriage and the thermal coupling is released. Is surely prevented.

  Thus, by thermally coupling the head case 11 that is an exterior member of the ink jet recording head I and the drive circuit 60, the heat of the drive circuit 60 is not only from the surface of the drive circuit 60 but also through the head case 11. It can dissipate heat into the air. That is, since the head case 11 is an exterior member of the ink jet recording head I, the heat of the drive circuit 60 can be radiated by touching the outside air. Therefore, it is possible to prevent the drive circuit 60 from being destroyed by heat, and it is not necessary to increase the size of the drive circuit 60 in order to improve the heat dissipation of the drive circuit 60, and the drive circuit 60 is reduced in size in accordance with the heat dissipation capability. be able to. Incidentally, since it is necessary to reduce the internal resistance of the drive circuit 60 in order to suppress the heat generation of the drive circuit 60, it is necessary to ensure the size of the transistor in the drive circuit 60. By thermally coupling to the head case 11, it is not necessary to ensure the size of the transistors in the drive circuit 60. Therefore, it is not necessary to reduce the internal resistance of the drive circuit 60, and it is possible to reduce the size in accordance with the heat dissipation capability and to reduce the cost.

  Further, by thermally coupling the drive circuit 60 to the head case 11, heat generation of the drive circuit 60 can be suppressed, and the current applied to the drive circuit 60 can be increased to improve the ink ejection characteristics and the ink. The continuous discharge performance can be improved. That is, the drive circuit 60 increases heat generation by increasing the current, and the heat dissipation time is shortened by continuously discharging, so that the current and continuous discharge performance are limited. By radiating this heat, the current flowing through the drive circuit 60 can be increased and continuous ejection can be performed at short intervals for a long time.

  The head case 11 is made of a synthetic resin material such as a modified PPE (polyphenylene ether) resin. In the present embodiment, the coupling region 17 where the driving circuit 60 of the head case 11 is thermally coupled is a material having a higher thermal conductivity than other regions, for example, a metal material such as copper, iron, aluminum, stainless steel, or the like. Formed with. Thus, by forming the coupling region 17 in which the drive circuit 60 of the head case 11 is thermally coupled with a material having high thermal conductivity, the heat of the drive circuit 60 can be radiated more efficiently.

  In the present embodiment, only the coupling region 17 where the drive circuit 60 of the head case 11 is thermally coupled is formed of a material having high thermal conductivity. However, the present invention is not limited to this. For example, the head case 11 The whole may be a synthetic resin, and the entire head case 11 may be a material such as a metal having high thermal conductivity. Incidentally, since the thermal conductivity of the resin material is about 0.1 W / m ° C., which is higher than the thermal conductivity of air, 0.02 W / m ° C., even the head case 11 made entirely of the resin material is driven. The heat from the circuit 60 can be efficiently radiated. Further, if the entire head case 11 is formed of a material having high thermal conductivity such as metal, the cost becomes high, the ink jet recording head I becomes heavy, and the carriage cannot be moved at a high speed and the carriage can be moved. A burden is placed on the motor to be moved. On the other hand, by forming only a part of the coupling region 17 of the head case 11 with a material having a relatively high thermal conductivity such as a metal, the cost can be reduced and the head case can be prevented from becoming heavy. There is a further effect of being able to.

  Further, the drive circuit 60 is thermally coupled to the head case 11 which is not a member (such as the flow path forming substrate 22) that substantially holds the piezoelectric element 40 but a member that is different from the member that holds the piezoelectric element 40, Heat at the time of driving the piezoelectric element 40 is not transmitted to the drive circuit 60 via the head case 11. Therefore, only the heat radiation of the drive circuit 60 can be efficiently performed by the head case 11.

(Other embodiments)
As mentioned above, although one Embodiment of this invention was described, the basic composition of this invention is not limited to what was mentioned above. For example, in the first embodiment described above, the drive circuit 60 of the flexible printed board 50 is provided so as to face the inner wall surface of the head case 11, and the drive circuit 60 and the inner wall surface of the head case 11 are connected so as to be able to conduct heat. However, the present invention is not limited to this. For example, in the flexible printed circuit board 50, the drive circuit 60 is mounted on the surface of the base film 52 opposite to the inner wall surface of the head case 11 due to differences in wiring and mounting surfaces. You may be made to do. In such a case, the drive circuit 60 is substantially thermally connected to the inner surface of the head case 11 by connecting the region of the base film 52 where the drive circuit 60 is mounted to the inner wall surface of the head case 11 so as to conduct heat. It is connected in a conductive manner.

  In addition, the ink jet recording heads of these embodiments constitute a part of a recording head unit having an ink flow path communicating with an ink cartridge or the like, and are mounted on the ink jet recording apparatus. FIG. 4 is a schematic view showing an example of the ink jet recording apparatus.

  As shown in FIG. 4, the recording head units 1A and 1B having the ink jet recording head 10 are detachably provided with cartridges 2A and 2B constituting ink supply means, and a carriage on which the recording head units 1A and 1B are mounted. 3 is provided on a carriage shaft 5 attached to the apparatus body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively.

  The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted is moved along the carriage shaft 5. The On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S which is a recording medium such as paper fed by a paper feed roller (not shown) is wound around the platen 8. It is designed to be transported.

  In the first embodiment described above, an ink jet recording head has been described as an example of a liquid ejecting head. However, the present invention is widely intended for all liquid ejecting heads, and ejects liquids other than ink. Of course, the invention can also be applied to a liquid jet head. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (field emission displays). Examples thereof include an electrode material ejection head used for electrode formation, a bioorganic matter ejection head used for biochip production, and the like.

FIG. 2 is an exploded perspective view of a recording head according to Embodiment 1 of the invention. FIG. 3 is a plan view of the recording head according to the first embodiment of the invention. FIG. 3 is a cross-sectional view of the recording head according to the first embodiment of the invention. 1 is a schematic view of an ink jet recording apparatus according to an embodiment of the present invention.

Explanation of symbols

  I ink jet recording head (liquid ejecting head), II ink jet recording apparatus (liquid ejecting apparatus), 10 head body, 11 head case (exterior member), 20 actuator unit, 21 pressure generating chamber, 22 flow path forming substrate, 23 Diaphragm, 24 Pressure generating chamber low plate, 30 Flow path unit, 31 Ink supply port forming substrate, 32 Reservoir, 33 Reservoir forming substrate, 34 Nozzle opening, 35 Nozzle plate, 40 Piezoelectric element, 43 Lower electrode film, 44 Piezoelectric body Layer, 45 upper electrode film, 46 individual connection terminal, 47 common connection terminal, 50 wiring board, 51 wiring layer, 52 base film, 53 insulating material, 60 drive circuit, 70 circuit board

Claims (7)

A head body comprising a pressure generating chamber communicating with a nozzle opening for ejecting liquid; and a pressure generating means for causing a pressure change in the pressure generating chamber; and electrically connected to the pressure generating means of the head body. A flexible printed circuit board on which a drive circuit for driving the pressure generating means is mounted; and an exterior member that holds the head body and includes the flexible printed circuit board.
The liquid ejecting head, wherein the driving circuit of the flexible printed circuit board is connected to an inner surface of the exterior member so as to be able to conduct heat.   The liquid ejecting head according to claim 1, wherein the exterior member is formed of a member having a heat dissipation property that is higher in a coupling region where the driving circuit is connected so as to be able to conduct heat compared to other regions.   The liquid ejecting head according to claim 1, wherein the exterior member is a head case provided with a circuit board to which the flexible printed board is connected.   The head case has a hollow box shape, and the flexible printed board is bent along a wall surface in the head case so that the drive circuit and the wall surface of the head case can conduct heat. The liquid ejecting head according to claim 3, wherein the liquid ejecting head is connected.   The liquid ejecting head according to claim 1, wherein the pressure generating unit is a piezoelectric element in a flexural vibration mode.   The liquid ejecting head according to claim 1, wherein the driving circuit and the exterior member are bonded via an adhesive having an electrothermal filler.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.

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