JP4194224B2 - Liquid discharge head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a liquid discharge head. To Related.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is a liquid discharge head that is an example of a microelectromechanical device used for an ink jet printer or the like that heats and foams liquid in a liquid flow path, and discharges liquid from a discharge port by pressure at the time of foaming. . In order to heat the liquid, a discharge heater is provided on the element substrate, and a driving voltage is supplied to the discharge heater via wiring on the element substrate.
[0003]
In recent years, in such a liquid discharge head, a cantilevered movable member supported at one end is arranged in the liquid flow path in order to guide most of bubbles at the time of foaming to the discharge port side and improve discharge efficiency. Proposed configuration is proposed. The movable member has one end fixedly supported on the element substrate and the other end extending into the liquid flow path so that the movable member is held at a certain interval on the element substrate. Is configured to be displaceable.
[0004]
[Problems to be solved by the invention]
Of the liquid discharge heads having the above-mentioned movable member in the liquid flow path, Japanese Patent Laid-Open No. 10-76659 discloses a configuration in which a discharge heater is provided on the movable member.
[0005]
However, in the configuration of the discharge heater described in Japanese Patent Laid-Open No. 10-76659, the electrodes 1204 and 1205 of the electrothermal transducer are formed so as to fold the surface of the movable member as shown in FIG. In such an electrothermal converter layout, the position of the discharge heater 1206 is asymmetric in the width direction of the movable member, and the movable member is easily twisted during foaming, so the durability of the movable member is not always sufficiently satisfied. There were cases where it was not possible. In addition, since the width of the electrode is not sufficient, the structure is not suitable for flowing a large current.
[0006]
Accordingly, an object of the present invention is to provide a liquid discharge head having high durability and reliability when the movable member in the liquid flow path has a discharge heater. Do It is to provide.
[0007]
[Means for Solving the Problems]
A feature of the present invention is a liquid discharge head having a substrate, a top plate bonded to the substrate, and a liquid flow path formed between the substrate and the top plate, and a fixed end fixed to the substrate. And a cantilevered movable member having a free end extending into the liquid flow path. The movable member includes a lower protective layer, a heating resistor layer, a lower electrode layer, an insulating layer, and an upper electrode from the substrate side. Layer and upper protective layer The surface of the lower protective layer facing the substrate is flat, and the heat generating portion of the heat generating resistance layer is formed symmetrically with respect to the width direction of the movable member, By applying a voltage to the heat generating portion, the liquid in the liquid flow path is caused to foam between the movable member and the substrate to discharge the liquid.
[0010]
The upper electrode layer and the lower electrode layer are preferably made of a refractory metal.
[0011]
The insulating layer is preferably SiN.
[0012]
The heating resistance layer is located upstream and downstream in the discharge direction of the heating section. beneath Electrically connected to the electrode layer Has been It is preferable.
[0013]
It is preferable that the upper electrode layer and the lower electrode layer are formed so as to extend from the front surface side to the back surface of the movable member.
Further, unlike the heat generating portion, the heater further includes an adjustment heater provided in the liquid flow path corresponding to the heat generating portion, and an adjustment heater driver for driving the adjustment heater. Also good.
[0014]
A voltage lower than the voltage applied to the heat generating portion may be applied to the adjustment heater.
[0015]
The top plate is provided with a voltage converter, and the voltage applied to the adjustment heater by the voltage converter may be lower than the voltage applied to the heat generating portion.
[0016]
The voltage applied to the adjustment heater may be lower than the voltage applied to the heat generation part by connecting a power supply different from the power supply connected to the heat generation part to the adjustment heater.
[0017]
The power supply connected to the adjustment heater may be a logic circuit power supply.
[0018]
The adjustment heater may be provided on the downstream side in the discharge direction of the heat generating portion.
[0019]
The adjustment heater may be provided on the upstream side in the discharge direction of the heat generating portion.
[0020]
A plurality of adjustment heaters may be provided, and may be provided on the upstream side and the downstream side in the discharge direction of the heat generating portion.
[0021]
The adjustment heater preferably has a smaller area than the heat generating portion.
[0022]
It is preferable that the adjustment heater driver has a smaller area than the heat generating portion driver.
[0023]
The signal generation unit of the heating unit driver and the adjustment heater driver may be common.
[0024]
The top plate may further include a sensor for detecting a state in the liquid flow path corresponding to the adjustment heater for each liquid flow path.
[0025]
The terms “upstream” and “downstream” used in the description of the present invention are related to the flow direction of the liquid from the liquid supply source to the discharge port through the bubble generation region (or the movable member), or the direction in this configuration. It is used as an expression.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0027]
[First Embodiment]
FIG. 1 shows a first embodiment of the present invention.
[0028]
As shown in FIG. 1, the liquid discharge head of the present embodiment includes a movable heater 207 provided with a discharge heater 207 on the element substrate 1 side installed in a liquid flow path 7 constituted by the element substrate 1 and the top plate 3. A member 206 is provided. The movable member 206 faces the element substrate 1 so as to divide the liquid channel 7 into a first liquid channel 7 a communicating with the discharge port 5 and a second liquid channel 7 b having the bubble generation region 10. These cantilever-shaped thin films are formed of a silicon-based material such as silicon nitride or silicon oxide.
[0029]
The movable member 206 has a fulcrum 6a on the upstream side of a large flow flowing from the common liquid chamber 8 to the discharge port 5 side through the movable member 206 by the liquid discharge operation, and a free end 6b on the downstream side of the fulcrum 6a. In order to cover the element substrate 1, the element substrate 1 is disposed at a position facing the element substrate 1 at a predetermined distance from the element substrate 1. A bubble generation region 10 is formed between the element substrate 1 and the discharge heater 207 provided on the movable member 206.
[0030]
The top plate 3 is for constituting a plurality of liquid flow paths 7 corresponding to the respective discharge heaters 207 and a common liquid chamber 8 for supplying liquid to the respective liquid flow paths 7. A liquid passage side wall 9 extending between the heaters 2 is integrally provided. The top plate 3 is made of a silicon-based material, and the pattern of the liquid flow path 7 and the common liquid chamber 8 is formed by etching, or silicon nitride, silicon oxide, or the like is formed on the silicon substrate by a known film formation method such as a CVD method. Then, after depositing a material for forming the liquid flow path side wall 9, the liquid flow path 7 can be formed by etching.
[0031]
In the orifice plate 4, a plurality of discharge ports 5 corresponding to the respective liquid flow paths 7 and communicating with the common liquid chamber 8 through the respective liquid flow paths 7 are formed. The orifice plate 4 is also made of a silicon-based material. For example, the orifice plate 4 is formed by cutting a silicon substrate on which the discharge ports 5 are formed to a thickness of about 10 to 150 μm. The orifice plate 4 is not necessarily required for the present invention. Instead of providing the orifice plate 4, the thickness of the orifice plate 4 is formed on the top surface of the top plate 3 when the liquid flow path 7 is formed on the top plate 3. By leaving a considerable wall and forming the discharge port 5 in this portion, a top plate with a discharge port can be obtained.
[0032]
Based on the above configuration, when the discharge heater 207 generates heat, heat acts on the liquid in the bubble generation region 10 between the element substrate 1 and the discharge heater 207, thereby causing a film boiling phenomenon on the surface of the discharge heater 207. Based on this, bubbles are generated and grow. The pressure accompanying the growth of the bubbles preferentially acts on the movable member 206, and the movable member 206 is displaced so as to open largely toward the discharge port 5 with the fulcrum 6a as the center, as indicated by a broken line in FIG. Depending on the displacement or the displaced state of the movable member 206, the propagation of pressure based on the generation of bubbles and the growth of the bubbles themselves are guided to the discharge port 5 side, and the liquid is discharged from the discharge port 5.
[0033]
That is, on the bubble generation region 10, the movable member 206 having the fulcrum 6 a on the upstream side (common liquid chamber 8 side) of the liquid flow in the liquid flow path 7 and the free end 6 b on the downstream side (discharge port 5 side). By providing the bubble, the pressure propagation direction of the bubble is guided to the downstream side, and the pressure of the bubble directly and efficiently contributes to the discharge. The bubble growth direction itself is guided in the downstream direction in the same manner as the pressure propagation direction, and grows larger downstream than upstream. Thus, by controlling the bubble growth direction itself with the movable member and controlling the bubble pressure propagation direction, the fundamental discharge characteristics such as discharge efficiency, discharge force, or discharge speed can be improved.
[0034]
On the other hand, when the bubble enters the defoaming step, the bubble rapidly disappears due to a synergistic effect with the elastic force of the movable member 206, and the movable member 206 finally returns to the initial position shown by the solid line in FIG. . At this time, in order to supplement the contraction volume of the bubbles in the bubble generation region 10 and also to supplement the volume of the discharged liquid, the liquid flows from the upstream side, that is, the common liquid chamber 8 side, and enters the liquid flow path 7. Liquid filling (refilling) is performed, and this liquid refilling is performed efficiently and reasonably and stably with the return action of the movable member 206.
[0035]
In addition, the liquid discharge head according to the present embodiment includes a circuit and an element for driving the discharge heater 207 and controlling the drive. These circuits and elements are allocated to the element substrate 1 or the top board 3 according to their functions. These circuits and elements can be easily and finely formed using a semiconductor wafer process technique because the element substrate 1 and the top plate 3 are made of silicon material.
[0036]
Next, a method for manufacturing the movable member 206 will be described with reference to FIGS.
[0037]
First, an IC is formed on a silicon substrate 501 on which an insulating layer 502 is stacked. , Arrangement The line 503 is formed to a thickness of about 1 μm by a sputtering method, and is patterned into a predetermined pattern by a photolithography method and a dry etching method. Next, as shown in FIG. 2A, an electrode protective layer 504 made of SiN is formed to a thickness of 1 μm by a CVD method. Next, as shown in FIG. 2B, a gap forming member 506 made of Al is formed to a thickness of about 5 μm by sputtering, and patterned into a predetermined pattern by photolithography and dry etching. Next, as shown in FIG. , A cavitation-resistant cavitation layer (Ta layer) 505 to be formed later is formed to a thickness of 2000 angstroms and patterned into a predetermined pattern by photolithography and dry etching. Next, as shown in FIG. 3A, a heater protective layer 507 made of SiN is formed to a thickness of 0.1 to 0.5 μm by a CVD method, and a through hole 520 is formed by a photolithography method and a dry etching method. , 521 are formed.
[0038]
Next, as shown in FIG. 3B, the resistance layer (discharge heater) 508 made of TaN has a thickness of 1000 angstroms, and the wiring 509 made of Cu is made 3000 angstroms as shown in FIG. 3C. The electrode and the heat action portion are formed by a photolithography method and an etching method. Accordingly, the wiring 509 connected to the resistance layer (ejection heater) 508 is connected to the wiring 503 through the through hole 520.
[0039]
Further, in order to improve the connectivity between the upper and lower folded wirings 511 and the VH wiring (signal voltage supply wiring), which will be described later, a wiring 509 made of Cu is used as an electrode portion so as to cover the through hole 521 of the gap forming member 506. It is formed.
[0040]
Next, as shown in FIG. 4A, a heat storage layer 510 made of SiO is formed to a thickness of 2.0 μm by the CVD method, and on the electrode portion 509 on the VH wiring by a photolithography method and an etching method. Through holes 522 and 523 are formed on the wiring 509 at the upper and lower folded portions of the resistance layer 508.
[0041]
Next, as shown in FIG. 4B, a wiring 511 which is an upper and lower folded line made of Cu is formed to a thickness of 5000 angstroms by sputtering. Then, patterning is performed in a predetermined pattern by photolithography and etching, and as a result, upper and lower folded wirings 509 and 511 that connect the resistance layer 508 and the wiring 503 are formed.
[0042]
Next, as shown in FIG. 4C, the protective layer 512 of the upper and lower folded wiring made of SiN is formed to a thickness of 1 μm by the CVD method. Next, the protective layer 512 and the anti-cavitation layer 505 are continuously patterned into the shape of the movable member 206 by a photolithography method and a dry etching method. Then, a part of the gap forming member 506 is removed by wet etching to form the movable member 206. Finally, electrode pads for connection to the outside are formed by photolithography and etching, and the state shown in FIG. 5 is obtained.
[0043]
Since the element substrate 1 and the top plate 3 are not provided with a heater, no wiring other than the wiring for connecting to the movable member 206 is formed.
[0044]
Thus, the substrate and bonded to the substrate Have Formed between the board and the top board. Have A liquid discharge head having a liquid flow path that is fixed to the substrate. Have The movable member has a cantilever-like movable member having a fixed end and a free end extending into the liquid flow path. The movable member includes a lower protective layer, a heating resistor layer, a lower electrode layer, and an insulating layer from the substrate side. , Upper electrode layer, upper protective layer And When the voltage is applied to the heat generating portion of the heat generating resistance layer, the liquid in the liquid flow path is foamed between the movable member and the substrate and the liquid is discharged, and the foaming surface of the movable member is flattened. And the durability of the heat generating part can be improved.
[0045]
In the above configuration, the gap forming member is provided on the substrate, and the lower protective layer, the heating resistor layer, the lower electrode layer, the insulating layer, the upper electrode layer, and the upper protective layer are sequentially stacked on the gap forming member from the substrate side. Stratify And removing the gap forming member Forming cantilevered movable members It can form by the process to do.
[0046]
The discharge heater 207 formed in the movable member formed in this way has a layer structure in which the layer below the resistance layer 508 is thinner than the upper layer, and thus foams on the lower layer side. Further, since the movable member 206 jumps upward due to the reaction at the time of foaming, there is less escape of ink to the rear, and the foaming efficiency is increased. Further, since the defoamed portion is not fixed to the surface by the movement of the foamed surface, cavitation concentration hardly occurs, and the life of the substrate 501 and the like is improved. Further, the discharge heater can be formed symmetrically in the width direction of the movable member, and the twist during the operation of the movable member can be reduced. And since there is no level | step difference of an electrode in the foaming surface side and it is a flat structure, it is hard to receive to the influence of a thermal shock and the lifetime of a movable member improves. Also, the insulating layer, which is the main material of the movable member, is usually composed of a ceramic material. By providing electrodes on both sides of this ceramic material, the insulating layer is reinforced, and the durability of the movable member is further improved. It is the composition to do.
[0047]
Furthermore, if the upper electrode layer and the lower electrode layer are formed of a refractory metal, hillocks and stress strains of both electrode layers can be prevented.
[0048]
[Second Embodiment]
FIG. 6 shows a second embodiment of the present invention. In the present embodiment, a discharge heater 207 is provided on the movable member 206, and a heating heater 208 is formed on the top plate 3 as in the first embodiment.
[0049]
First, as an embodiment applicable to the present invention, a first substrate for configuring a plurality of discharge ports that discharge liquid, and a plurality of liquid flow paths that are joined to each other and communicate with the discharge ports, respectively, and A second substrate; a plurality of energy conversion elements disposed in each liquid flow path for converting electrical energy into liquid discharge energy in the liquid flow path; and for controlling the drive conditions of the energy conversion elements A liquid discharge head having a plurality of elements or electric circuits having different functions and having the elements or electric circuits distributed to the first substrate and the second substrate according to the functions will be described.
[0050]
Fig. 7 Is shown schematically. As shown in FIG. 7A, the substrate 1 is provided with a plurality of ejection heaters and their drivers, a time-division control logic circuit, and a shift register. As shown in FIG. 7B, the top plate 3 is provided with a control circuit including a heater for heating (adjustment heater, control heater) and a sensor, a driver thereof, a voltage converter, a memory, and the like. . Since the size of the heater and the sensor can be optimized, the size of the heater and the driver can be reduced. This voltage converter is provided in order to make the voltage applied to the adjustment (heating) heater lower than the voltage applied to the discharge heater.
[0051]
In this embodiment, the heater 208 for heating is operated according to the temperature of the liquid to adjust the viscosity of the liquid, so that the discharge performance is always kept constant. That is, when the liquid in the vicinity of the discharge port has a high viscosity, the heater 208 for heating can be operated at an appropriate timing to locally heat and reduce the viscosity of the liquid. Thereby, desired ejection characteristics can be obtained. The heater 208 for heating is disposed directly above the discharge heater or close to the discharge port, can reduce the viscous resistance in front and around the valve, and enables stable discharge. By making this heater 208 in the top plate 3, the liquid discharge head itself can be miniaturized. In addition, the heater 208 and its driving element can be disposed at any position regardless of the discharge heater 207 provided on the element substrate 1 and its driving element and wiring pattern. Since the liquid can be arranged at an optimum place for heating the liquid and has a high degree of freedom in terms of space, it is possible to reduce the size of the liquid discharge head itself by arranging the members in a compact manner.
[0052]
The advantage of the configuration in which the heater 208 for heating is arranged on the top plate 3 will be described in more detail. In this configuration, the discharge heater 207 is configured on the element substrate 1 using a semiconductor process, and the discharge amount is applied to the top plate 3 that configures the liquid channel 7 by bonding to the element substrate 1 for each liquid channel 7. A heater 208 for controlling the heating, a driving element (driver) for driving the heater 208, and a drive control circuit are arranged. As a result, the degree of freedom such as the resistance, shape, driving voltage, and driving pulse width of the heater 208 is large. For example, as shown in FIG. 10 (a), the heater 208 can be driven by a short pulse at the same voltage as the discharge heater 207, or the heater 208 for discharge can be discharged as shown in FIG. 10 (b). It is also possible to drive with a long pulse at a voltage lower than that of the heater 2. This is because the heater 208 for heating is disposed on the top plate 3, so that it is released from the restrictions due to the foaming conditions of the discharge heater 207. Further, with the recent increase in the density of recording elements (360 dpi or more), the heating heater 208, a driving element (driver) for driving the heater 208, and a control logic circuit are provided on the element substrate 1 on which the ejection heater 2 is provided in terms of layout. Is difficult to mount while securing the degree of freedom such as the drive pulse width as described above. However, in the present embodiment, since the heating heater 208 and the heating heater driver are mounted on the top plate 3, it can be realized while ensuring the above-described degree of freedom.
[0053]
Also, the liquid discharge amount varies depending on the balance between the flow resistance ahead and the flow resistance behind the foaming center. When the flow resistance behind is constant, the smaller the front flow resistance, the lower the liquid discharge amount. Will increase. Therefore, in this embodiment, only the liquid in front is heated by the heating heater 208 provided downstream in the ejection direction of the discharge heater before foaming. That is, a driving pulse that causes a heating action to warm only the liquid in front is supplied to the heater 208 for heating. In this way, the amount of discharge can be controlled by controlling the energy applied to the heater 208 to control the viscosity of the liquid and substantially changing the forward flow resistance.
[0054]
Conventionally, there has been a configuration in which a heating heater is arranged in front of a discharge heater on the same substrate, but in this case, it is difficult to arrange the heating heater in front because of restrictions on layout. However, in this embodiment, an independent drive element (driver) or the like is provided corresponding to each heating heater 208, and a driving voltage lower than the driving voltage of the discharge heater can be supplied. Can be placed in an optimal size and position. In addition, the size of the entire chip is not increased. In addition, as a means for making the voltage applied to the heater for heating lower than the voltage applied to the heater for discharge, it can be performed by connecting a separate power source to the top plate in addition to using a voltage converter. Further, if the logic circuit power supply is used as another power supply, it is not necessary to newly increase the power supply.
[0055]
Furthermore, if the signal generators of the discharge heater driver and the adjustment heater driver are common, the discharge heater and the adjustment heater can be driven in synchronization.
[0056]
When the top plate further includes a sensor for detecting the state in the liquid flow path corresponding to the adjustment heater for each liquid flow path, the state of the liquid flow path is adjusted independently of the discharge heater. It becomes possible to adjust with.
[0057]
Next, a configuration for distributing circuits and elements to the element substrate 1 and the top plate 3 will be described.
[0058]
8A and 8B are diagrams for explaining the circuit configuration of the liquid discharge head shown in FIG. 6, in which FIG. 8A is a plan view of the element substrate, and FIG. 8B is a plan view of the top plate. In addition, Fig.8 (a) and (b) represent the mutually opposing surface.
[0059]
As shown in FIG. 8A, the element substrate 1 includes a plurality of discharge heaters 207 arranged in parallel, a driver 11 that drives these discharge heaters 207 in accordance with image data, and an input image. An image data transfer unit 12 that outputs data to the driver 11 and a sensor 13 that measures parameters necessary for controlling the driving conditions of the ejection heater 2 are provided.
[0060]
The image data transfer unit 12 includes a shift register that outputs image data input serially to each driver 11 in parallel, and a latch circuit that temporarily stores data output from the shift register. Note that the image data transfer unit 12 may output image data individually corresponding to each discharge heater 2, or the arrangement of the discharge heaters 207 is divided into a plurality of blocks, and the image corresponding to the block unit. It may be one that outputs data. In particular, it is possible to easily cope with the increase in printing speed by providing a plurality of shift registers for one head and distributing and inputting data transfer from the recording apparatus to the plurality of shift registers.
[0061]
As the sensor 13, a temperature sensor that measures the temperature near the discharge heater 207, a resistance sensor that monitors the resistance value of the discharge heater 207, or the like is used.
[0062]
When considering the ejection amount of the ejected droplets, the ejection amount is mainly related to the foaming volume of the liquid. The foaming volume of the liquid varies depending on the discharge heater 207 and the surrounding temperature. Therefore, the temperature of the discharge heater 207 and the surrounding temperature are measured by a temperature sensor, and before applying a heat pulse for liquid discharge according to the result, a pulse of energy that does not discharge liquid (preheat pulse) is applied. In addition, by changing the pulse width of the preheat pulse and the output timing thereof, the discharge heater 207 and the surrounding temperature are adjusted to maintain the image quality by discharging a certain droplet. .
[0063]
Further, when considering the energy required for foaming the liquid in the discharge heater 207, if the heat dissipation condition is constant, the energy is the energy input per unit area required for the discharge heater 207 and the discharge heater. It is represented by the product of the area of 207. Thus, the voltage applied to both ends of the discharge heater 207, the current flowing through the discharge heater 207, and the pulse width may be set to values at which the necessary energy can be obtained. Here, the voltage applied to the ejection heater 207 can be kept substantially constant by supplying the voltage from the power source of the liquid ejection apparatus body. On the other hand, regarding the current flowing through the discharge heater 207, the resistance value of the discharge heater 207 depends on the lot or the element substrate 1 due to variations in the film thickness of the discharge heater 207 in the manufacturing process of the element substrate 1. Will be different. Therefore, when the applied pulse width is constant and the resistance value of the discharge heater 207 is larger than the set value, the flowing current value becomes small, and the amount of energy input to the discharge heater 207 becomes insufficient, and the liquid Cannot be properly foamed. Conversely, when the resistance value of the discharge heater 207 decreases, the current value becomes larger than the set value even when the same voltage is applied. In this case, excessive energy is generated by the discharge heater 207, which may lead to damage or short life of the discharge heater 207. Accordingly, there is a method in which the resistance value of the discharge heater 207 is constantly monitored by a resistance sensor, and the power supply voltage and the heat pulse width are changed according to the value, so that substantially constant energy is applied to the discharge heater 207.
[0064]
On the other hand, as shown in FIG. 8B, the top plate 3 is provided on the element substrate 1 in addition to the grooves 3a and 3b forming the liquid flow path and the common liquid chamber as described above. A sensor drive unit 17 that drives the sensor 13 and a discharge heater control unit 16 that controls a drive condition of the discharge heater 207 based on an output result from the sensor driven by the sensor drive unit 17 are provided. The top plate 3 has a supply port 3c that communicates with the common liquid chamber in order to supply liquid from the outside to the common liquid chamber.
[0065]
Furthermore, in order to electrically connect a circuit or the like formed on the element substrate 1 and a circuit or the like formed on the top plate 3 to the mutually facing portions of the joint surface of the element substrate 1 and the top plate 3 respectively. Contact pads 14 and 18 are provided. The element substrate 1 is provided with external contact pads 15 that serve as input terminals for external electric signals. The size of the element substrate 1 is larger than the size of the top plate 3, and the external contact pad 15 is provided at a position exposed from the top plate 3 when the element substrate 1 and the top plate 3 are joined.
[0066]
Here, an example of a procedure for forming circuits and the like on the element substrate 1 and the top plate 3 will be described.
[0067]
For the element substrate 1, first, circuits constituting the driver 11, the image data transfer unit 12, and the sensor 13 are formed on a silicon substrate using a semiconductor wafer process technique. Next, the discharge heater 2 is formed as described above, and finally the connection contact pad 14 and the external contact pad 15 are formed.
[0068]
As for the top plate 3, first, the circuits constituting the discharge heater control unit 16 and the sensor driving unit 17 are formed on a silicon substrate by using a semiconductor wafer process technique. Next, as described above, the grooves 3a and 3b and the supply port 3c constituting the liquid flow path and the common liquid chamber are formed by the film forming technique and etching, and finally the contact pad 18 for connection is formed.
[0069]
When the element substrate 1 and the top plate 3 configured as described above are aligned and joined, the discharge heaters 207 are disposed corresponding to the respective liquid flow paths, and the connection pads 14 and 18 are respectively connected. The circuit etc. which were formed in the element substrate 1 and the top plate 3 are electrically connected through this. For example, the electrical connection may be performed by placing gold bumps or the like on the connection pads 14 and 18, but other methods may be used. Thus, the electrical connection between the element substrate 1 and the top plate 3 is performed by the connection contact pads 14, 18, so that the above-described circuits are electrically connected simultaneously with the joining of the element substrate 1 and the top plate 3. It can be performed. After the element substrate 1 and the top plate 3 are joined, the orifice plate 4 is joined to the tip of the liquid flow path 7, thereby completing the liquid ejection head. In the above description, the structure for electrical connection of the discharge heater 207 provided on the element substrate 1 has been described in detail. However, the electrical connection of the heater 208 provided on the top plate 3 is not described. With regard to the configuration for this, the top plate 3 or the like is provided with a configuration substantially similar to that described above. Since it overlaps with the above description, the description is omitted here.
[0070]
When the liquid discharge head thus obtained is mounted on a head cartridge or a liquid discharge device, as shown in FIG. 9, the liquid discharge head is fixed on a base substrate 22 on which a printed wiring board 23 is mounted. The unit 20 is used. In FIG. 9, a printed wiring board 23 is provided with a plurality of wiring patterns 24 that are electrically connected to the head controller of the liquid ejection device. These wiring patterns 24 are connected to the external contact pads 15 via bonding wires 25. And electrically connected. Since the external contact pad 15 is provided only on the element substrate 1, the electrical connection between the liquid discharge head 21 and the outside can be performed in the same manner as a conventional liquid discharge head. Here, an example in which the external contact pads 15 are provided on the element substrate 1 has been described, but the external contact pads 15 may be provided only on the top plate 3 instead of the element substrate 1.
[0071]
As described above, various circuits for driving and controlling the discharge heater 207 are distributed to the element substrate 1 and the top plate 3 in consideration of the electrical connection between them, so that these circuits 1 Since it does not concentrate on one substrate, the liquid discharge head can be downsized. Further, the electrical connection between the circuit and the like provided on the element substrate 1 and the circuit and the like provided on the top plate 3 is performed by the connection contact pads 14 and 18, so that the number of electrical connection portions to the outside of the head is reduced. It is possible to reduce, improve reliability, reduce the number of parts, and further reduce the size of the head.
[0072]
In addition, by dispersing the above-described circuit and the like on the element substrate 1 and the top plate 3, the yield of the element substrate 1 can be improved, and as a result, the manufacturing cost of the liquid ejection head can be reduced. Furthermore, since the element substrate 1 and the top plate 3 are made of a material based on the same material called silicon, the thermal expansion coefficients of the element substrate 1 and the top plate 3 are equal. As a result, even if the element substrate 1 and the top plate 3 are thermally expanded by driving the discharge heater 207, there is no deviation between them, and the positional accuracy between the discharge heater 207 and the liquid flow path 7 is maintained well.
[0073]
In the present embodiment, the above-described circuits and the like are distributed according to their functions. The concept that serves as a reference for this distribution will be described below.
[0074]
A circuit corresponding to each discharge heater 207 by electrical wiring connection individually or in units of blocks is formed on the element substrate 1. In the example shown in FIG. 8, the driver 11 and the image data transfer unit 12 correspond to this. Since the drive signals are given in parallel to the discharge heaters 207, it is necessary to route the wiring by the amount corresponding to the signals. Therefore, when such a circuit is formed on the top plate 3, the number of connections between the element substrate 1 and the top plate 3 is increased, and there is a high possibility that a connection failure will occur. Connection failure between the heater 207 and the circuit is prevented.
[0075]
An analog portion such as a control circuit is easily affected by heat, and thus is provided on a substrate on which the discharge heater 207 is not provided, that is, the top plate 3. In the example shown in FIG. 8, the discharge heater control unit 16 corresponds to this.
[0076]
The sensor 13 may be provided on the element substrate 1 or the top plate 3 as necessary. For example, in the case of a resistance sensor, the resistance sensor is provided on the element substrate 1 because it is meaningless unless the resistance sensor is provided on the element substrate 1 or the measurement accuracy is lowered. In the case of a temperature sensor, it is preferable that the temperature sensor is provided on the element substrate 1 in order to detect a temperature rise due to an abnormality in the heater drive circuit, but the ink state is determined by the temperature rise via the ink described later. If desired, it is preferably provided on the top plate 3 or both the element substrate 1 and the top plate 3.
[0077]
In addition, a circuit that does not correspond to each discharge heater 2 individually or in block units by electrical wiring connection, a circuit that does not necessarily need to be provided on the element substrate 1, or a circuit that is provided on the top plate 3 does not affect the measurement accuracy. Sensors and the like are formed on the element substrate 1 or the top plate 3 as necessary so as not to concentrate on either the element substrate 1 or the top plate 3. In the example shown in FIG. 8, the sensor drive unit 17 corresponds to this.
[0078]
By providing each circuit, sensor, etc. on the element substrate 1 and the top plate 3 based on the above concept, each circuit, sensor, etc., while minimizing the number of electrical connections between the element substrate 1 and the top plate 3 as much as possible. Can be distributed in a well-balanced manner.
[0079]
As described above, it is preferable that the drive elements and the like directly connected in correspondence with the discharge heaters 207 provided in large numbers on the element substrate 1 are arranged on the element substrate 1. The circuit to be controlled is not necessarily arranged on the element substrate 1, and may be appropriately arranged in any vacant space of the element substrate 1 and the top plate 3. The same applies to the heater 208 for heating. That is, driving elements and the like directly connected to the heating heaters 208 provided in large numbers on the top board 3 are arranged on the top board 3, and a circuit for controlling the driving timing of the driving elements, etc. Are appropriately arranged in any vacant space of the element substrate 1 and the top plate 3.
[0080]
[Third Embodiment]
FIG. 11 shows a third embodiment of the present invention. The same components as those in the first and second embodiments are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, two heaters 209 are disposed in one liquid flow path 7 upstream and downstream of the discharge heater 207, respectively. According to this configuration, the refill (refilling) characteristics after discharging the liquid are improved, and the meniscus can be stabilized.
[0081]
[Fourth Embodiment]
FIG. 12 shows a fourth embodiment of the present invention. The same components as those in the first to third embodiments are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, similarly to the first embodiment, a discharge heater 207 is provided on the element substrate 1, and a heating heater 211 is formed on the movable member 210 provided on the top plate 3. The configuration of the top plate 3 itself is the same as that of the first embodiment, the configuration of the movable member 211 is substantially the same as that of the movable member 206 of the sixth embodiment, and the manufacturing method thereof includes the element substrate 1. There is no point which should be changed in particular except replacing with the top plate 3. According to the present embodiment, the viscosity of the liquid can be lowered by the heater 211 and the discharge performance can be maintained. In particular, since the heater 211 for heating is formed on the movable member 210 located in the liquid flow path 7, the heating efficiency is good. The discharge heater 2 and its driving element are allocated to the element substrate 1 and the heating heater 211 and its driving element are allocated to the movable member 210, respectively. Can be easily driven.
[0082]
[Fifth Embodiment]
FIG. 13 shows a fifth embodiment of the present invention. The same components as those in the first to fourth embodiments are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, as in the ninth embodiment, the discharge heater 2 is provided on the element substrate 1, the heater 211 is provided on the movable member 210, and the top plate 3 is provided in the same manner as in the first embodiment. Another heater 212 is formed. The configuration of the top 3 is the same as that of the first embodiment. According to the present embodiment, in addition to the effects of the ninth embodiment, the refill (refilling) characteristics after liquid ejection are improved, and the meniscus can be stabilized.
[0083]
【The invention's effect】
In a liquid discharge head having a substrate, a top plate bonded to the substrate, and a liquid flow path formed between the substrate and the top plate, a fixed end fixed to the substrate, and a liquid flow path The movable member has a cantilever-like movable member having a free end extending to the substrate, and the movable member includes a lower protective layer, a heating resistor layer, a lower electrode layer, an insulating layer, an upper electrode layer, and an upper protective layer from the substrate side. Stacked in order The surface of the lower protective layer facing the substrate is flat, and the heat generating portion of the heat generating resistance layer is formed symmetrically with respect to the width direction of the movable member, When the voltage is applied to the heat generating part, the liquid in the liquid flow path is foamed between the movable member and the substrate and the liquid is discharged, so that the foaming surface of the movable member can be flattened, and heat is generated. The durability of the part can be improved.
[0084]
In the above configuration, the gap forming member is provided on the substrate, and the lower protective layer, the heating resistor layer, the lower electrode layer, the insulating layer, the upper electrode layer, and the upper protective layer are sequentially stacked on the gap forming member from the substrate side. Stratify And removing the gap forming member Forming cantilevered movable members It can form by the process to do.
[0085]
If the upper electrode layer and the lower electrode layer are formed of a refractory metal, hillocks and stress strains of both electrode layers can be prevented.
[0086]
Unlike the heat generation part, an adjustment heater provided in the liquid flow path corresponding to the heat generation part and an adjustment heater driver for driving the adjustment heater are provided, and for adjustment If the heater is configured to be applied with a voltage lower than the voltage applied to the heat generating part, it can be placed at an optimal location according to the function, and can be arranged at a higher density than before, and the size of the head can be reduced. It also contributes to Furthermore, the manufacturing yield of the chip can be improved and the manufacturing cost of the head can be reduced. In addition, since the heat generating portion and the functional element can be controlled independently, optimal driving can be performed.
[0087]
When the heat generating part or the functional element is provided in the movable member arranged in the liquid flow path, it is effective for space saving and head size reduction, and the efficiency of liquid heating is improved.
[0088]
If the power source connected to the adjustment heater is a logic circuit power source, there is no need to prepare a new power source.
[0089]
If the adjustment heater is provided on the downstream side in the discharge direction of the heat generating portion, the viscosity of the liquid in the vicinity of the discharge port can be controlled, so that the discharge amount can be controlled.
[0090]
When the adjustment heater is provided on the upstream side in the discharge direction of the heat generating portion, the refill characteristic after the liquid discharge can be improved.
[0091]
If a plurality of adjustment heaters are provided and provided on the upstream side and the downstream side in the discharge direction of the heat generating portion, the refill characteristics after the liquid discharge can be improved and the meniscus can be stabilized.
[0092]
If the adjustment heater has a smaller area than the heat generating portion, it can be laid out at a desired position with respect to the heat generating portion in the liquid flow path.
[0093]
When the signal generation unit of the heat generating unit driver and the adjustment heater driver are common, the heat generation unit and the adjustment heater can be driven in synchronization.
[0094]
If the top plate further includes a sensor for detecting the state in the liquid flow path corresponding to the adjustment heater for each liquid flow path, the state in the liquid flow path can be adjusted by the adjustment heater independently of the heat generating portion. It becomes possible to adjust.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view taken along a liquid flow path for explaining the structure of a liquid discharge head according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view for explaining the first half of the manufacturing method of the liquid discharge head according to the first embodiment of the present invention.
FIG. 3 is a cross-sectional view for explaining an intermediate step in the method of manufacturing the liquid ejection head according to the first embodiment.
FIG. 4 is a cross-sectional view for explaining a latter half of the manufacturing method of the liquid ejection head according to the first embodiment.
FIG. 5 is a partially enlarged cross-sectional view of the liquid ejection head according to the first embodiment.
FIG. 6 is a cross-sectional view taken along a liquid flow path for explaining the structure of a liquid discharge head according to a second embodiment of the present invention.
7A is a schematic view of a substrate of the liquid discharge head shown in FIG. 6, and FIG. 7B is a schematic view of a top plate.
8A and 8B are diagrams for explaining a circuit configuration of the liquid discharge head shown in FIG. 6, in which FIG. 8A is a plan view of an element substrate, and FIG. 8B is a plan view of a top plate.
9 is a plan view of a liquid discharge head unit on which the liquid discharge head shown in FIG. 6 is mounted.
10A is a waveform diagram showing an example of drive pulses for the discharge heater and the heater for the liquid discharge head shown in FIG. 6, and FIG. 10B is a waveform diagram showing another example.
FIG. 11 is a cross-sectional view taken along a liquid flow path for explaining the structure of a liquid discharge head according to a third embodiment of the present invention.
FIG. 12 is a cross-sectional view taken along a liquid flow path for explaining the structure of a liquid discharge head according to a fourth embodiment of the present invention.
FIG. 13 is a cross-sectional view taken along a liquid flow path for explaining the structure of a liquid discharge head according to a fifth embodiment of the present invention.
FIG. 14 is a schematic diagram showing a configuration in which a discharge heater is provided on a conventional movable member.
[Explanation of symbols]
1 Element substrate
3 Top plate
3a, 3b groove
3c Supply port
5 Discharge port
4 Orifice plate
6a fulcrum
6b Free end
7 Liquid flow path
7a First liquid flow path
7b Second liquid flow path
8 Common liquid chamber
9 Liquid channel side wall
10 Bubble generation area
11 Driver
12 Image data transfer unit
13 Sensor
14 Contact pads for connection
15 External contact pad
16 Discharge heater controller
17 Sensor drive
18 Contact pads for connection
20 Liquid discharge head unit
22 Base substrate
23 Printed circuit board
206 Movable member
207 Discharge heater
208,209 Heater for heating
210 Movable member
211,212 Heater for heating
501 substrate
502 Insulating layer
503 Wiring
504 Electrode protective layer
505 Anti-cavitation layer
506 Gap forming member
507 Heater protective layer
508 resistance layer
509 Wiring
510 heat storage layer
511 wiring
512 Protective layer
520, 521, 522, 523 Through hole

Claims (11)

In a liquid discharge head having a substrate, a top plate bonded to the substrate, and a liquid flow path formed between the substrate and the top plate,
A cantilevered movable member having a fixed end fixed to the substrate and a free end extending into the liquid flow path;
The movable member is laminated in order of a lower protective layer, a heating resistor layer, a lower electrode layer, an insulating layer, an upper electrode layer, and an upper protective layer from the substrate side, and a surface of the lower protective layer facing the substrate is flat. There, the heat generating portion of the heat generating resistor layer is formed symmetrically with respect to a width direction of the movable member, the liquid movable member of the liquid flow path by applying a voltage to the heating portion and the substrate A liquid discharge head, wherein the liquid is discharged by bubbling between the two. The liquid discharge head according to claim 1, wherein the upper electrode layer and the lower electrode layer are formed of a refractory metal. The liquid ejection head according to claim 1, wherein the insulating layer is SiN. 4. The liquid discharge head according to claim 1, wherein the heat generation resistance layer is electrically connected to the lower electrode layer upstream and downstream in the discharge direction of the heat generation portion. The liquid discharge head according to claim 4, wherein the upper electrode layer and the lower electrode layer are formed so as to extend from the front surface side to the back surface of the movable member. Unlike the heat generating part, an adjustment heater provided in the liquid flow path corresponding to the heat generating part,
The liquid discharge head according to claim 1, further comprising an adjustment heater driver for driving the adjustment heater.   The liquid discharge head according to claim 6, wherein a voltage lower than a voltage applied to the heat generating portion is applied to the adjustment heater.   The liquid discharge head according to claim 7, wherein the top plate is provided with a voltage converter, and a voltage applied to the adjustment heater by the voltage converter is lower than a voltage applied to the heat generating portion. .   The voltage applied to the adjustment heater is lower than the voltage applied to the heat generating part by connecting a power supply different from the power supply connected to the heat generating part to the adjustment heater. Item 8. The liquid discharge head according to Item 7.   The liquid discharge head according to claim 9, wherein a power source connected to the adjustment heater is a logic circuit power source.   The liquid discharge head according to claim 6, wherein the adjustment heater is provided on the downstream side in the discharge direction of the heat generating portion.

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