JP2008036936A - Inkjet recording head and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable it to suppress the manufacturing cost of an inkjet recording head, to inhibit the bad influence of the fall of durability caused by the un-stabilization of a wiring state due to the cutting off of wiring and the vibration of an oscillating board and to make an ink delivery state stabilized. <P>SOLUTION: The inkjet recording head includes a piezoelectric element equipped with a first electrode, a piezoelectric body and a second electrode, a drive signal generating means which forms a drive signal for driving the piezoelectric element by the signal received from outside, an oscillating board which oscillates following the driving of the piezoelectric element and a pressure chamber whose one-side face is sealed with the oscillating board and which communicates with a nozzle. The first electrode is provided with a first part which oscillates with the piezoelectric body, a second part joined to an electrode pad of the drive signal generating means and a third part which lies between the first part and the second part while having the width of the direction perpendicular to the arrangement direction of the first part and the second part which is smaller than the width of the first part and the second part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording head and an image forming apparatus, and more particularly, to a technique for electrically connecting wiring from an electrode of a piezoelectric element to drive signal generating means.

  The following conventional techniques exist as a method for electrically connecting the wiring from the electrodes of the piezoelectric element to the drive signal generating means.

  FIG. 19 is a cross-sectional view of the ink jet recording head disclosed in Patent Document 1. As shown in FIG. 19, in the ink jet recording head of Patent Document 1, a first lid member 104 (vibration plate) including a first terminal 103 wired from an individual electrode 102 of a piezoelectric element 101, a second The drive signal generation means 106 provided with the terminal 105 is provided, and the opposing terminals of the first terminal 103 and the second terminal 105 are joined to each other.

FIG. 20 is a cross-sectional view of the ink jet recording head disclosed in Patent Document 2. As shown in FIG. 20, in the ink jet recording head disclosed in Patent Document 2, the piezoelectric element 201 is removed from the upper electrode film 202 via a conductive adhesive 206 that is located on the vibration plate 207 and seals the sealing space. The lead electrode 203 that is a lead line is electrically connected to the drive system wiring 205 that is connected to each terminal of the integrated circuit 204 that is a collection drive signal generating means.
Japanese Patent No. 3613302 JP 2002-292971 A

  However, in both Patent Documents 1 and 2, the wirings from the individual electrodes 102 and the upper electrode film 202 of the piezoelectric elements 101 and 201 are once mounted on the diaphragms 104 and 207 and then electrically connected to the drive signal generation means 106 and 204 therefrom. ing. For this reason, the former wiring increases the manufacturing process of the head and increases the cost.

  In addition, due to the wiring from the individual electrode 102 and the upper electrode film 202 existing on the surface of the piezoelectric body to the diaphragms 104 and 207, the occurrence of disconnection (disconnection) in the stepped portion and the influence of vibration in the diaphragms 104 and 207. As a result, the wiring state becomes unstable and reliability may be reduced.

  Further, there is no suggestion about a control method related to the temperature of the ink that affects the viscosity of the ink, and there is a possibility that the ejection state of the ink cannot be stabilized.

  The present invention has been made in view of such circumstances, can reduce the manufacturing cost of the head, and is durable due to the occurrence of disconnection of the wiring and the instability of the wiring state due to the influence of vibration on the diaphragm. It is an object of the present invention to provide an ink jet recording head that can suppress the influence of the deterioration of the properties and can stabilize the ink ejection state.

  In order to achieve the object, the invention according to claim 1 is directed to a piezoelectric element including a first electrode, a piezoelectric body, and a second electrode, and a drive signal for driving the piezoelectric element by an external signal. In an ink jet recording head comprising: a drive signal generating means for generating; a vibration plate that vibrates as the piezoelectric element is driven; and a pressure chamber that is sealed on one surface by the vibration plate and communicates with a nozzle. The first electrode is sandwiched between the first part and the second part, the first part that vibrates together with the piezoelectric body, the second part joined to the electrode pad of the drive signal generating means, and the first part. And a third part having a width in a direction perpendicular to the arrangement direction of the part and the second part, the first part and a third part smaller than the width of the second part.

  According to the present invention, the first electrode is sandwiched between the first part and the second part, and the width in the direction perpendicular to the arrangement direction of the first part and the second part is smaller than the width of the first part. Since the portion is provided, even when the first portion vibrates due to the piezoelectric drive of the diaphragm, the vibration is absorbed by the third portion, so that the vibration is absorbed in the second portion. I don't get it. For this reason, the bonding between the electrode pad of the drive signal generating means and the second portion of the first electrode is maintained in a stable state.

  Further, since the electrode pad of the drive signal generating means and the second portion of the first electrode of the piezoelectric element are joined, there is no need to perform wiring from the first electrode to the diaphragm as in the prior art, and the wiring structure is reduced. It is simple and can be wired at low cost, and the production cost of the head can be reduced. Further, there is no possibility of disconnection of the wiring, the wiring state is stabilized, the influence of the decrease in durability can be suppressed, and a highly reliable head can be configured.

  Note that if both the drive signal generating means and the diaphragm are made of a material having the same thermal expansion coefficient, there is no fear of warping at the time of joining or temperature change.

  Further, the diaphragm may be used as the second electrode of the piezoelectric element.

  In order to achieve the above object, according to a second aspect of the present invention, in the ink jet recording head according to the first aspect, the drive signal generating means and the diaphragm have a temperature detection pad, and are electrically conductive with each other. It connects by a connection member, It is characterized by the above-mentioned.

  According to the present invention, since the temperature detection pad of the drive signal generating means and the temperature detection pad of the diaphragm are directly connected, the temperature of the diaphragm can be measured by the temperature sensor of the drive signal generating means in a very short time. Can be detected. And a diaphragm can be driven according to the temperature of a diaphragm by controlling a drive signal within a drive signal generating means according to detected temperature information. Here, the temperature of the diaphragm is correlated with the temperature of the liquid in the pressure chamber. The temperature of the liquid is also correlated with the viscosity of the liquid. From the above, according to the present invention, the drive signal can be controlled in the drive signal generating means in accordance with the viscosity of the liquid affected by the change in the temperature of the liquid, so that the discharge operation of the nozzle can be stabilized. Can be planned.

  The drive terminal of the drive signal generating means may also serve as the temperature detection terminal.

  In order to achieve the above object, according to a third aspect of the present invention, in the ink jet recording head according to the second aspect, the temperature detection pad of the diaphragm is provided at a position facing the partition of the pressure chamber. It is characterized by that.

  According to the present invention, since the temperature detection pad of the diaphragm is provided at a position facing the side wall portion of the pressure chamber having high rigidity, it is not easily affected by vibration due to the driving of the diaphragm. Therefore, the connection between the temperature detection pad of the drive signal generating means and the temperature detection pad of the diaphragm is maintained in a stable state, and the temperature of the diaphragm can be reliably measured by the temperature sensor in the drive signal generating means. . Accordingly, since the drive signal can be controlled in the drive signal generating means according to the viscosity of the liquid more reliably, the ejection operation of the nozzle can be more reliably stabilized.

  In order to achieve the above object, according to a fourth aspect of the present invention, there is provided an ink jet recording head according to any one of the first to third aspects, wherein the drive signal generating means has two electrode pads on one side. It is characterized by being arranged in a staggered manner in a plurality of rows greater than or equal to the row.

  According to the present invention, even when the arrangement density of the pressure chambers is high and the arrangement density of the piezoelectric elements is high, the electrode pad of the drive signal generating means and the first electrode of the piezoelectric element can be reliably bonded.

  In order to achieve the above object, a fifth aspect of the present invention is an image forming apparatus comprising the ink jet recording head according to the first to fourth aspects.

  According to the present invention, it is possible to reduce the manufacturing cost of the head, and to suppress the influence of the deterioration of durability due to the occurrence of the disconnection of the wiring or the instability of the wiring state due to the vibration of the diaphragm. In addition, the ink ejection state can be stabilized.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Description of inkjet recording head]
<First Embodiment>
FIG. 1 is an external perspective view showing a part of an ink jet recording head of the present invention. Note that a partial perspective view is shown. 2 is a partial cross-sectional view in the longitudinal direction of the ink jet recording head shown in FIG. In addition, it is AA sectional drawing in Fig.3 (a) mentioned later in detail.

  As shown in FIGS. 1 and 2, the ink jet recording head includes a nozzle plate 12, a pressure chamber 14, a flow path forming substrate 15, a vibration plate 16 (including an upper electrode 21 </ b> A, a piezoelectric body 20, and a lower electrode 21 </ b> B). 22, a semiconductor integrated circuit 24, a common flow path 26, and the like.

  The nozzle plate 12 has a plurality of nozzles 32 for ejecting ink. Each nozzle 32 communicates with the corresponding pressure chamber 14. The pressure chamber 14 is formed between the flow path forming substrate 15 and the vibration plate 16.

  A piezoelectric element 22 is provided on the diaphragm 16 in an overlapping manner, and the piezoelectric element 22 includes an upper electrode 21A, a piezoelectric body 20, and a lower electrode 21B.

  The upper electrode 21A and the semiconductor integrated circuit 24 are directly bonded using a conductive adhesive 48 having a conductive filler between the electrode pad 34 and the electrode pad 36, and have a constant interval. Note that the upper electrode 21A and the semiconductor integrated circuit 24 may be directly bonded without using the conductive adhesive 48 by providing terminals. In this way, the electrode pad 36 of the semiconductor integrated circuit 24 and the electrode pad 34 of the upper electrode 21A of the piezoelectric element 22 are directly joined, so that wiring from the upper electrode 21A to the diaphragm 16 is once performed as in the prior art. This eliminates the need for wiring, simplifies the wiring structure, enables wiring at low cost, and reduces the manufacturing cost of the head. Further, there is no possibility of disconnection of the wiring, the wiring state is stabilized, the influence of the decrease in durability can be suppressed, and a highly reliable head can be configured.

  Further, the semiconductor integrated circuit 24 is made of silicon having the same thermal expansion coefficient as that of the diaphragm 16, and there is no possibility of warping or disconnection due to bonding or temperature change. The common flow channel 26 communicates with the pressure chamber 14 communicating with the nozzle 32 and is a flow channel for supplying ink to the pressure chamber 14.

  As shown in FIG. 10 to be described later, a protective film 37 of the piezoelectric body 20 is also formed. However, for convenience of explanation, the protective film 37 is omitted in FIGS.

  3A is a view showing the structure of the upper surface of the diaphragm 16 before the upper electrode 21A and the semiconductor integrated circuit 24 are joined, and FIG. 3B is an enlarged top view of the piezoelectric element 22. FIG. . (C) is a diagram showing the structure of the upper surface of the diaphragm 16 when electrode pads 36 of the semiconductor integrated circuit 24 to be described later are arranged in a staggered arrangement in two rows on one side.

  As shown in FIG. 3A, a plurality of piezoelectric elements 22 are provided on the upper surface of the diaphragm 16 over the left and right sides. Each piezoelectric element 22 is provided with an upper electrode 21A. Here, as shown in FIG. 3B, the upper electrode 21 </ b> A of the present invention has a characteristic shape, and is divided into each part of a vibrating part 42, a constricted part 44, and a pad part 46. Note that FIG. 3C will be described later.

  When the upper electrode 21 </ b> A is viewed from the upper surface, the vibrating portion 42 is formed in a rectangular shape having a width W, and the pad portion 46 has a width equivalent to the width W of the vibrating portion 42. The constricted portion 44 is formed with a width ω smaller than the width W of the vibrating portion 42 while being sandwiched between the vibrating portion 42 and the pad portion 46, thereby forming a constricted shape. The pad portion 46 includes an electrode pad 34 that is directly bonded to the electrode pad 36 of the semiconductor integrated circuit 24. The vibrating portion 42, the constricted portion 44, and the pad portion 46 are disposed on the same surface of the upper surface of the piezoelectric element 22.

  Under such a configuration, the ink jet recording head of the present invention operates as follows as a characteristic operation.

  The semiconductor integrated circuit 24 outputs a drive signal from the outside to the upper electrode 21 </ b> A of the piezoelectric element 22 through the electrode pad 36, the conductive adhesive 48, and the electrode pad 34. The piezoelectric element 22 receives the drive signal and causes flexural vibration, and the ink is ejected from the nozzle 32 by contracting the pressure chamber 14. When the drive signal is no longer output, the pressure chamber 14 returns to the original state, and ink is supplied from the common flow path 26 to the pressure chamber 14.

  In the present invention, as shown in FIGS. 3A and 3B, the upper electrode 21 </ b> A of the piezoelectric element 22 has a characteristic shape having a constricted portion 44. For this reason, when the piezoelectric element 22 receives a drive signal and causes a flexural vibration, a flexural vibration is generated in the vibration portion 42. The flexural vibration portion is formed in accordance with the shape of the pressure chamber immediately below, and is constricted. In the portion 44, almost no flexural vibration is generated. Therefore, the pad portion 46 is not affected by the bending deformation of the flexural vibration portion, and the bonding state of the upper electrode 21A bonded by the electrode pad 36, the conductive adhesive 48, and the electrode pad 34 and the semiconductor integrated circuit 24 is stabilized. Can be achieved.

  The above is the characteristic operation of the ink jet recording head of the present invention.

  Next, a modified example of the semiconductor integrated circuit 24 will be described. FIG. 4 is a bottom view of the semiconductor integrated circuit 24. In the present embodiment, the case where the electrode pads 36 are arranged in one row on one side as shown in FIG. 4A is considered, but in addition, the electrode pads 36 are arranged in two rows on one side as shown in FIG. A staggered arrangement is also conceivable. As shown in FIG. 4B, when the pad density of the semiconductor integrated circuit 24 becomes rate-determining by arranging two rows on one side in a staggered manner, the number of rows on one side is two or more than two rows on one side. Staggered to avoid density problems.

  As a more specific example, in the case of the arrangement of one row on one side shown in FIG. 4A, it is conceivable to arrange one row of about 150 pieces on one side per inch. On the other hand, in the case of the staggered arrangement shown in FIG. 4B, the pitch width is twice the pitch width where the pressure chambers 32 are arranged, and the arrangement is two rows of about 75 pieces per inch. Conceivable. In the same way, not only one row on one side and two rows on one side, but also a pitch width N times the pitch width in which the pressure chambers 32 are arranged can be considered as an array of N rows on one side.

  4B, when the upper electrode 21A and the semiconductor integrated circuit 24 are joined to each other, the structure of the upper surface of the diaphragm 16 is as shown in FIG. 3C. become. As shown in FIG. 3C, the arrangement of the pad portion 46 is matched with the arrangement of the electrode pad 36 of the semiconductor integrated circuit 24.

  As shown in FIGS. 4A and 4B, in addition to the electrode pads 36 for piezoelectric elements, electrode pads 45 for control lines and power supply lines are provided on the lower surface of the semiconductor integrated circuit 24. .

  Next, the manufacturing process of the ink jet recording head of the present invention will be described.

  FIG. 5 is a diagram of the silicon substrate 13 on which the pressure chambers 14 and the like are formed. As a manufacturing process, first, the silicon substrate 13 is processed by wet etching or dry etching from both sides. Then, as shown in FIG. 5, the pressure chamber 14, the flow path 17 that connects the pressure chamber 14 and the nozzle 32, the supply throttle 18 that connects the supply system and the pressure chamber, and a part of the supply flow path 19 from the ink tank are formed. The As a specific example of the silicon substrate 13, it is conceivable to use a silicon substrate having a thickness of 250 μm or 625 μm. Further, the pressure chamber 14, the supply throttle 18 that connects the supply system and the pressure chamber 14, and a part of the supply flow path 19 from the ink tank are processed from the upper side of FIG. 5, while the flow path that connects the pressure chamber 14 and the nozzle 32. May be processed from the lower side of FIG. 5, or all may be processed from the upper side of FIG. The silicon substrate 13 becomes the flow path forming substrate 15.

  Next, FIG. 6 is a schematic diagram of the manufacturing process of the nozzle plate 12. As shown in FIG. 6A, an SOI substrate 29 including an active layer 23, a BOX layer 27, and a handle layer 28 is prepared. As shown in FIG. 6B, the active layer 23 is etched from the upper side to the BOX layer 27. As the etching process, it may be processed into a tapered shape by wet etching, or may be processed substantially vertically by dry etching. Further, it may be processed into a tapered shape by combining anisotropic and isotropic dry etching. The active layer 23 becomes the nozzle plate 12. As a specific example of the SOI substrate 29, the active layer 23 having a thickness of about 20 μm and the handle layer 28 having a thickness of about 200 to 400 μm can be considered.

  Next, FIG. 7 is a view showing a state in which the flow path forming substrate 15 and the nozzle plate 12 are joined. As a bonding method, a method by direct bonding without using an intermediate layer, a method in which a thermal oxide film / pre-oxide film is formed between both substrates and bonded via this, or Au or the like between two layers is used. A method in which metal is vapor-deposited or sputtered is used as an intermediate layer, and a method in which one side is joined using pyrex glass or the like and an electric field is used. In order to improve workability, the flow path forming substrate 15 and the nozzle plate 12 are joined in a state where the BOX layer 27 and the handle layer 28 are formed on the nozzle plate 12.

  Next, FIG. 8 is a diagram showing how the diaphragm 16 is formed. FIG. 8A shows a state where the SOI substrate 35 and the flow path forming substrate 15 are joined. As shown in FIG. 8A, an SOI substrate 35 including an active layer 30, a BOX layer 31, and a handle layer 33 is prepared and bonded between the active layer 30 and the flow path forming substrate 15. As in the above, the bonding method is a method by direct bonding without using an intermediate layer, a method in which a thermal oxide film / pre-oxide film is formed between both substrates, and bonding is performed via this method, or two layers For example, a method in which a metal such as Au is vapor-deposited or sputtered is used as an intermediate layer and bonded thereto. In addition, as a specific example of the SOI substrate 35, the active layer 30 having a thickness of 5 to 10 μm is conceivable.

  Subsequently, as shown in FIG. 8B, after the handle layer 33 and the BOX layer 31 of the SOI substrate 35 are ground, they are removed by wet etching or CMP (Chemical Mechanical Polishing), and only the active layer 30 of the SOI substrate 35 is removed. Alternatively, only the active layer 30 and the BOX layer 31 are left to be bonded to the flow path forming substrate 15. The active layer 30 becomes the diaphragm 16.

  In addition, FIG.8 (c) is a figure which shows a modification. As shown in FIG. 8C, the pressure chamber 14 is filled in advance with a sacrificial member 53 such as metal or glass without using the SOI substrate 35, and then the upper surface is flattened, and PZT is sputtered or SiO2 on the upper surface. It is good also as a diaphragm 16 by forming into a film about 5-10 micrometers by CVD. The metal or glass as the sacrificial member 53 is then melted and removed.

  Next, FIG. 9 is a diagram showing a state in which the piezoelectric element 22 is formed. As shown in FIG. 9, the lower electrode 21B of the piezoelectric element 22 is patterned on the diaphragm 16, the piezoelectric body 20 is formed, the upper electrode 21A is formed, and the piezoelectric body 20 and the upper electrode 21A are patterned. In sequence, the piezoelectric element 22 made of PZT is formed immediately above the pressure chamber 14.

  Either the upper electrode 21A or the lower electrode 21B is used as an individual electrode or a common electrode. In addition, although not shown in figure, the process which isolate | separates into an individual electrode by an etching after making an individual electrode common once and polarizing a piezoelectric material once may be put.

  Next, FIG. 10 is a diagram showing the formation of the protective film of the piezoelectric body 20. As shown in FIG. 10A, in order to prevent the piezoelectric short-circuit breakdown due to the creeping current, an insulating protective film 37 such as SiO 2 is formed on the side surface of the piezoelectric body 20 by CVD or the like. Thereafter, as shown in FIG. 10B, a portion A that becomes the ink supply portion and a portion B that forms the electrode of the piezoelectric body 20 (a portion corresponding to the pad portion 46 of the upper electrode 21A in FIG. 3B). The protective film 37 is removed by etching. Then, as shown in FIG. 10C, a portion C indicated by an arrow is further opened as a supply channel using the protective film 37 as a mask.

  Next, FIG. 11 is a diagram showing how the upper handle layer is attached and the nozzle finish. As shown in FIG. 11A, the adhesiveness is deactivated when heated on the upper part of the structure formed by the handle layer 28, the nozzle plate 12, the flow path forming substrate 15, the vibration plate 16, the piezoelectric element 22, and the like. The thermoplastic bonding layer 39 is formed by spin coating or dry film laminating. Then, an upper handle layer 47 such as Si is attached through the bonding layer 39. Thereafter, as shown in FIG. 11B, the handle layer 28 of the nozzle plate 12 is removed, and a liquid repellent layer 49 is formed by plating or vapor deposition. Furthermore, it separates into individual head units using a dicer.

  Here, as shown in FIG. 11C, the processing is continued with the handle layer 28 not completely removed, leaving a certain thickness, and before the liquid repellent layer 49 is formed, the surface side of the nozzle 32 Then, the deeply processed handle layer 28 having a certain thickness may be deeply etched by dry etching or the like to form a tapered straight nozzle, and then the liquid repellent layer 49 may be formed. In this case, accuracy of the processing depth is required, and alignment accuracy according to the position of the mask is required.

  Next, FIG. 12 is a diagram showing a state of electrical connection. As shown in FIG. 12, the bonding layer 39 and the upper handle layer 47 are removed by heating, the flow path member 54 is attached to the upper part of the individual unit of the head, and the semiconductor integrated circuit 24 for electrical connection is attached. The attachment may be performed directly by flip chip bonding or FPC.

  The above is the description of the manufacturing process of the ink jet recording head of the present invention.

  Next, the overall structure of the ink jet recording head of the present invention will be described. FIG. 13 is a perspective plan view showing an example of the overall structure of the ink jet recording head 11 of the present invention. In order to increase the dot pitch printed on the recording paper, it is necessary to increase the nozzle pitch in the head. In this embodiment, as shown in FIG. 13, the ink chamber units (droplet discharge elements) including the nozzles 32 serving as ink discharge ports and the pressure chambers 14 corresponding to the nozzles 32 are staggered for two rows. A plurality of the ink chamber unit groups arranged are arranged in the head longitudinal direction (direction perpendicular to the paper feed direction) with the common flow path 26 interposed therebetween. As shown in FIG. 13, the plurality of ink chamber unit groups arranged in the longitudinal direction of the head are arranged while gradually shifting the position in the lateral direction of the head (paper feeding direction). This achieves a high density of substantial nozzle intervals (projection nozzle pitch) projected so as to be aligned along the longitudinal direction of the head.

<Second Embodiment>
FIG. 14 is a partial cross-sectional view in the direction perpendicular to the longitudinal direction of the ink jet recording head shown in FIG. 1. The vibration plate 16, the piezoelectric element 22, and the semiconductor integrated circuit 24 of the ink jet recording head according to the second embodiment. FIG.

  The semiconductor integrated circuit 24 may generate heat during driving, and the diaphragm 16 may generate heat when vibrated by a driving signal. Since the viscosity of the ink changes depending on the temperature, the heat generation of the semiconductor integrated circuit 24 and the diaphragm 16 may affect the ink ejection operation. Therefore, as shown in FIG. 14, each of the diaphragm 16 and the semiconductor integrated circuit 24 is provided with temperature detection pads 38 and 40 for measuring the temperature of the diaphragm 16, and a conductive adhesive having a conductive filler with each other. 41 to connect. Then, the temperature of the diaphragm 16 and the semiconductor integrated circuit 24 is measured.

  The diaphragm 16 and the semiconductor integrated circuit 24 are respectively provided with control power pads 43 and 45 for controlling and powering the semiconductor integrated circuit 24, and are connected to each other by a conductive adhesive 41 having a conductive filler. The electrode pad 34 of the upper electrode 21A of the piezoelectric element 22 and the electrode pad 36 of the semiconductor integrated circuit 24 are connected by a conductive adhesive 48 having a conductive filler.

  In addition, an alignment mark 50 is formed on the diaphragm 16, so that alignment at the time of joining the diaphragm 16 and the semiconductor integrated circuit 24 becomes easy.

  Here, the surface of the upper electrode 21 </ b> A provided with the electrode pad 34 in the piezoelectric element 22 is about several μm to 10 μm corresponding to the thickness of the piezoelectric element 22 and is higher than the surface of the diaphragm 16. Therefore, by using the conductive adhesive 41 having a conductive filler of 10 μm or more, when the core of the conductive filler is an elastic body, the thickness of the piezoelectric body 20 is absorbed, and problems such as poor electrical connection do not occur. In addition, even when the conductive adhesive filler core is not an elastic body, the size of the filler core of the conductive adhesive 41 is changed in accordance with the thickness of the piezoelectric body 20 so as to correspond to the plurality of types of conductive adhesives. To. Specifically, when the thickness of the piezoelectric body 20 is 5 μm to 10 μm, the thickness of the piezoelectric body 20 is a, and the diameter of the conductive adhesive 41 used on the surface of the upper electrode 21A is b. The diameter of the conductive filler of the conductive adhesive 56 used on the surface of the pad 38 may be approximately a + b.

  Here, the measurement of the temperature of the diaphragm 16 will be described in more detail.

  15A is a partial cross-sectional view in the longitudinal direction of the ink jet recording head shown in FIG. 1, and FIG. 15B is a bottom view of the semiconductor integrated circuit 24. FIG.

  As shown in FIGS. 15A and 15B, the diaphragm 16 and the semiconductor integrated circuit 24 are each provided with temperature detection pads 38 and 40 for measuring the temperature of the diaphragm 16, and are electrically conductive fillers. 41 to connect. The conductive filler 41 used for connection is not particularly limited as long as it is a highly conductive material. For example, gold, silver, copper, lead, an alloy of silver and lead, carbon, nickel, and the like are conceivable.

  Here, the portion surrounded by the dotted line in FIGS. 15A and 15B shows a corresponding region where the nozzle 32 is disposed. And as shown to Fig.15 (a), in this embodiment, the position which arrange | positions the pad 38 for temperature detection is devised. Specifically, no connection path to the pressure chamber 14 or the nozzle 32 is formed immediately below the diaphragm 16, and the temperature detection pad 38 is provided in a highly rigid portion directly above the partition wall of the pressure chamber 14. Deploy. With this arrangement, the connection state between the temperature detection pad 40 of the semiconductor integrated circuit 24 and the temperature detection pad 38 of the diaphragm 16 is stabilized, and the temperature of the diaphragm 16 can be accurately measured. .

  Since the temperature detection pad 38 needs to transmit the temperature of the diaphragm 16 to the sensor mounted on the semiconductor integrated circuit 24, the material is aluminum, copper, gold, platinum, iridium having good thermal conductivity. Any metal or ceramic may be used. If the material is metal, it can be formed in a common process if it is used as a pad for electrical connection. When ceramics are used, the pad may be formed as a dummy structure that does not function as a piezoelectric vibrator, and formed as a protrusion at the same time as the piezoelectric vibrator is formed, and an upper electrode may be formed. By doing so, the connection is strengthened and the temperature can be detected more reliably. The adhesive used as the base of the conductive adhesive is not particularly limited, and examples thereof include an adhesive such as an epoxy resin, a polyester resin, an acrylic resin, a polyimide resin, and a polysulfone resin.

  Other configurations and operations are the same as those in the first embodiment.

[Overall configuration of inkjet recording apparatus]
Next, the structure of an ink jet recording apparatus will be described as an image forming apparatus using the ink jet recording head of the present invention.

  FIG. 16 is an overall configuration diagram showing an outline of the ink jet recording apparatus. As shown in FIG. 16, the ink jet recording apparatus 110 includes a print unit 112 having a plurality of print heads 11K, 11C, 11M, and 11Y provided for each ink color, and each print head 11K, 11C, 11M, and 11Y. An ink storage / loading unit 114 that stores ink to be supplied to the printer, a paper feeding unit 118 that supplies recording paper 116, a decurling unit 120 that removes curling of the recording paper 116, and a nozzle surface of the printing unit 112 A suction belt conveyance unit 122 that is arranged opposite to the (ink ejection surface) and conveys the recording paper 116 while maintaining the flatness of the recording paper 116; a print detection unit 124 that reads a printing result by the printing unit 112; And a paper discharge unit 126 that discharges printed recording paper (printed matter) to the outside.

  In the case of an apparatus configuration using roll paper, a cutter 128 is provided as shown in FIG. 16, and the roll paper is cut into a desired size by the cutter 128. The cutter 128 includes a fixed blade 128A having a length equal to or larger than the conveyance path width of the recording paper 116, and a round blade 128B that moves along the fixed blade 128A. The fixed blade 128A is provided on the back side of the print. The round blade 128B is arranged on the printing surface side with the conveyance path interposed therebetween. Note that the cutter 128 is not necessary when cut paper is used.

  The recording paper 116 delivered from the paper supply unit 118 retains curl due to having been loaded in the magazine. In order to remove this curl, the decurling unit 120 applies heat to the recording paper 116 by the heating drum 130 in the direction opposite to the curl direction of the magazine.

  After the decurling process, the cut recording paper 116 is sent to the suction belt conveyance unit 122. The suction belt conveyance unit 122 has a structure in which an endless belt 133 is wound between rollers 131 and 132, and at least a portion facing the nozzle surface of the printing unit 112 and the sensor surface of the printing detection unit 124 is flat. It is configured to make.

  The belt 133 has a width that is wider than the width of the recording paper 116, and a plurality of suction holes (not shown) are formed on the belt surface. As shown in FIG. 16, an adsorption chamber 134 is provided at a position facing the nozzle surface of the print unit 112 and the sensor surface of the print detection unit 124 inside the belt 133 spanned between the rollers 131 and 132. The suction chamber 134 is sucked by the fan 135 to make a negative pressure, whereby the recording paper 116 on the belt 133 is sucked and held.

  The power of a motor (not shown) is transmitted to at least one of the rollers 131 and 132 around which the belt 133 is wound, whereby the belt 133 is driven in the clockwise direction in FIG. 16 and is held on the belt 133. The recording paper 116 is conveyed from left to right in FIG.

  Since ink adheres to the belt 133 when a borderless print or the like is printed, the belt cleaning unit 136 is provided at a predetermined position outside the belt 133 (an appropriate position other than the print region).

  A heating fan 140 is provided on the upstream side of the printing unit 112 on the paper conveyance path formed by the suction belt conveyance unit 122. The heating fan 140 heats the recording paper 116 by blowing heated air onto the recording paper 116 before printing. Heating the recording paper 116 immediately before printing makes it easier for the ink to dry after landing.

  The printing unit 112 is a so-called full line type head in which a line type head having a length corresponding to the maximum paper width is arranged in a direction (main scanning direction) orthogonal to the paper transport direction (sub scanning direction) ( FIG. 17).

  As shown in FIG. 17, each of the print heads 11K, 11C, 11M, and 11Y constituting the print unit 112 discharges ink over a length exceeding at least one side of the maximum-size recording paper 116 that is the target of the inkjet recording apparatus 110. It is composed of a line type head in which a plurality of outlets (nozzles) are arranged.

  Printing corresponding to each color ink in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side (left side in FIG. 17) along the conveyance direction (paper conveyance direction) of the recording paper 116. Heads 11K, 11C, 11M, and 11Y are arranged. A color image can be formed on the recording paper 116 by ejecting the color inks from the respective print heads 11K, 11C, 11M, and 11Y while conveying the recording paper 116.

  As described above, according to the printing unit 112 in which the full line head that covers the entire paper width is provided for each ink color, the recording paper 116 and the printing unit 112 are relatively moved in the paper transport direction (sub-scanning direction). It is possible to record an image on the entire surface of the recording paper 116 by performing this operation only once (that is, in one sub-scan). Accordingly, high-speed printing is possible as compared with a shuttle type head in which the print head reciprocates in a direction (main scanning direction) orthogonal to the paper transport direction, and productivity can be improved.

  As shown in FIG. 17, the ink storage / loading unit 114 has tanks that store inks of colors corresponding to the print heads 11K, 11C, 11M, and 11Y, and each tank has a pipeline that is not shown. The print heads 11K, 11C, 11M, and 11Y communicate with each other.

  The print detecting unit 124 includes an image sensor (line sensor or the like) for imaging the droplet ejection result of the printing unit 112, and means for checking nozzle clogging and other ejection defects from the droplet ejection image read by the image sensor. Function as.

  A post-drying unit 142 is provided following the print detection unit 124. The post-drying unit 142 is means for drying the printed image surface, and for example, a heating fan is used.

  A heating / pressurizing unit 144 is provided following the post-drying unit 142. The heating / pressurizing unit 144 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 145 having a predetermined uneven surface shape while heating the image surface, and transfers the uneven shape to the image surface. To do.

  The printed matter generated in this manner is outputted from the paper output unit 126. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. The ink jet recording apparatus 110 is provided with sorting means (not shown) for switching the paper discharge path in order to select the print product of the main image and the print product of the test print and send them to the discharge units 126A and 126B. ing. Note that when the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by the cutter (second cutter) 148. The cutter 148 is provided immediately before the paper discharge unit 126, and cuts the main image and the test print unit when the test print is performed on the image margin. The structure of the cutter 148 is the same as that of the first cutter 128 described above, and includes a fixed blade 148A and a round blade 148B.

  Although not shown, the paper output unit 126A for the target prints is provided with a sorter for collecting prints according to print orders.

[Explanation of control system]
FIG. 18 is a block diagram illustrating a system configuration of the inkjet recording apparatus 110. As shown in the figure, the inkjet recording apparatus 110 includes a communication interface 170, a system controller 172, an image memory 174, a ROM 175, a motor driver 176, a heater driver 178, a print control unit 180, an image buffer memory 182, a head driver 184, and the like. It has.

  The communication interface 170 is an interface unit (image input unit) that functions as an image input unit that receives image data sent from the host computer 186.

  Image data sent from the host computer 186 is taken into the inkjet recording apparatus 110 via the communication interface 170 and temporarily stored in the image memory 174. The image memory 174 is a storage unit that stores an image input via the communication interface 170, and data is read and written through the system controller 172.

  The system controller 172 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 110 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. .

  The ROM 175 stores a program executed by the CPU of the system controller 172 and various data necessary for control (including test pattern data for measurement such as landing position error).

  The image memory 174 is used as a temporary storage area for image data, and is also used as a program development area and a calculation work area for the CPU.

  The motor driver 176 is a driver (driving circuit) that drives the conveyance motor 188 in accordance with an instruction from the system controller 172. The heater driver 178 is a driver that drives the heater 189 such as the post-drying unit 142 in accordance with an instruction from the system controller 172.

  In accordance with the control of the system controller 172, the print control unit 180 performs various processes, corrections, and the like for generating a droplet ejection control signal from image data (multi-value input image data) in the image memory 174. In addition to functioning as signal processing means, it also functions as drive control means for controlling the ejection drive of the head 150 by supplying the generated ink ejection data to the head driver 184.

  An outline of the flow of processing from image input to print output is as follows. Image data to be printed is input from the outside via the communication interface 170 and stored in the image memory 174. At this stage, for example, RGB multivalued image data is stored in the image memory 174.

  In the ink jet recording apparatus 110, a pseudo continuous tone image is formed by changing the droplet ejection density and dot size of fine dots with ink (coloring material) to the human eye. It is necessary to convert to a dot pattern that reproduces the gradation (shading of the image) as faithfully as possible. Therefore, the original image (RGB) data stored in the image memory 174 is converted into dot data for each ink color via the print controller 180 via the system controller 172.

  The head driver 184 outputs a drive signal for driving the actuator 158 corresponding to each nozzle 32 of the head 150 in accordance with the print contents based on the ink ejection data and the drive waveform signal given from the print control unit 180. The head driver 184 may include a feedback control system for keeping the head driving condition constant.

  In this way, the drive signal output from the head driver 184 is applied to the head 150, whereby ink is ejected from the corresponding nozzle 32. An image is formed on the recording paper 116 by controlling ink ejection from the head 150 in synchronization with the conveyance speed of the recording paper 116.

  As described above, based on the ink discharge data and the drive signal waveform generated through the required signal processing in the print control unit 180, control of the discharge amount and discharge timing of the ink droplets from each nozzle through the head driver 184. Is done. Thereby, a desired dot size and dot arrangement are realized.

  As described with reference to FIG. 16, the print detection unit 124 is a block including an image sensor. The print detection unit 124 reads an image printed on the recording paper 116, performs necessary signal processing, and the like to perform a print status (whether ejection is performed, droplet ejection, and the like). Variation, optical density, etc.) and the detection result is provided to the print controller 180 and the system controller 172.

  The print control unit 180 performs various corrections on the head 150 based on information obtained from the print detection unit 124 as necessary, and performs cleaning operations (nozzle recovery operation) such as preliminary ejection, suction, and wiping as necessary. Perform the controls to be implemented.

  According to the inkjet recording apparatus 110 having the above configuration, a good image with reduced density unevenness can be obtained.

  Although the ink jet recording head and the image forming apparatus of the present invention have been described in detail above, the present invention is not limited to the above examples, and various improvements and modifications are made without departing from the gist of the present invention. Of course.

1 is an external perspective view showing a part of an ink jet recording head of the present invention. FIG. 3 is a partial cross-sectional view in the longitudinal direction of the ink jet recording head shown in FIG. 1 (A-A cross-sectional view in FIG. 3A). It is a figure which shows the structure of the upper surface of the diaphragm before joining of an upper electrode and a semiconductor integrated circuit. It is an enlarged top view of a piezoelectric element. It is a figure which shows the structure of the upper surface of the diaphragm before joining an upper electrode and a semiconductor integrated circuit (when the electrode pad of a semiconductor integrated circuit is made into the zigzag arrangement | sequence of 2 rows on one side). It is a bottom view of a semiconductor integrated circuit. It is a figure of the silicon substrate in which the pressure chamber etc. were formed. It is a schematic diagram of the manufacturing process of a nozzle plate. It is a figure which shows the state with which the silicon substrate in which the pressure chamber etc. were formed, and the nozzle plate were joined. It is a figure which shows the mode of formation of a diaphragm. It is a figure which shows the state in which the piezoelectric element was formed. It is a figure which shows formation of a piezoelectric material protective film. It is a figure which shows the mode of attachment of an upper handle layer, and a nozzle finish. It is a figure which shows the mode of electrical connection. 2 is a perspective plan view showing an example of the overall structure of the ink jet recording head of the present invention. FIG. FIG. 2 is a partial cross-sectional view in the direction perpendicular to the longitudinal direction of the ink jet recording head shown in FIG. 1. 2A is a partial cross-sectional view in the longitudinal direction of the ink jet recording head shown in FIG. 1, and FIG. 2B is a bottom view of the semiconductor integrated circuit. 1 is an overall configuration diagram showing an outline of an inkjet recording apparatus. It is a principal part top view of the printing part periphery of an inkjet recording device. It is a block diagram which shows the system configuration | structure of an inkjet recording device. 2 is a cross-sectional view illustrating an ink jet recording head disclosed in Patent Document 1. FIG. 6 is a cross-sectional view showing an ink jet recording head disclosed in Patent Document 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 ... Nozzle plate, 14 ... Pressure chamber, 16 ... Vibrating plate, 20 ... Piezoelectric body, 21A ... Upper electrode, 21B ... Lower electrode, 22 ... Piezoelectric element, 24 ... Semiconductor integrated circuit, 26 ... Common flow path, 32 ... Nozzle 34 ... Electrode pad (upper electrode side) 36 ... Electrode pad (semiconductor integrated circuit side) 38 ... Temperature detection pad (upper electrode side) 40 ... Temperature detection pad (semiconductor integrated circuit side) 41 ... Conductive Adhesive, 42 ... pressurizing part, 43 ... control power supply pad (upper electrode side), 44 ... constriction part, 45 ... control power supply pad (semiconductor integrated circuit side), 46 ... pad part, 48 ... conductive adhesive, 50 ... Alignment mark

Claims (5)

A piezoelectric element including a first electrode, a piezoelectric body, and a second electrode; drive signal generating means for generating a drive signal for driving the piezoelectric element by an external signal; and vibration accompanying driving of the piezoelectric element In an ink jet recording head having a vibrating plate, and a pressure chamber having one surface sealed by the vibrating plate and communicating with a nozzle,
The first electrode is sandwiched between the first part and the second part, the first part that vibrates together with the piezoelectric body, the second part joined to the electrode pad of the drive signal generating means, and the first part. A third portion that is smaller than the width of the first portion and the second portion with respect to the width in the direction perpendicular to the arrangement direction of the portion and the second portion;
An ink jet recording head. The ink jet recording head according to claim 1,
The drive signal generating means and the diaphragm have a temperature detection pad, and are connected to each other by a conductive connection member;
An ink jet recording head. The ink jet recording head according to claim 2,
The temperature detection pad of the diaphragm is provided at a position facing the partition of the pressure chamber;
An ink jet recording head. In the ink jet recording head according to any one of claims 1 to 3,
The drive signal generating means is arranged such that the electrode pads are arranged in a zigzag manner in two or more rows on one side,
An ink jet recording head.   An image forming apparatus comprising the ink jet recording head according to claim 1.

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