JP2002321374A - Liquid ejection head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a liquid ejection head densified and longer by improving molding precision and filling property to suppress deformation and warping of a top plate in manufacturing the top plate constituting the liquid ejection head. SOLUTION: The top plate 5 constituting the liquid ejection head is divided into a first base 21 consisting of an orifice plate lower half part 6c containing the ejection ports 6a and nozzle arrays 7, with the upper vicinity of the nozzle array 7 and ejection ports 6a being as a boundary face 23, and a second base 22 consisting of the orifice plate upper half part 6d, a liquid chamber 8 and a liquid supply port 9. The first base 21 and the second base 22 are integrally bonded by a two-color molding for molding by a first and a second molding. A pin point gate as the first molding gate of the first base 21 is arranged on the boundary face 23 above the nozzle arrays 7 to improve the filling property of the thin part of the nozzle arrays and the orifice plate 6 or the secondary molding gate of the second base 22 is arranged on the longitudinal direction side face of the top plate 5 to flow plastic resin in the direction of the liquid channel arrays of the top plate 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid discharge head for discharging a liquid such as ink from a discharge port as flying liquid droplets to perform printing and recording on a recording medium and to form an image.

[0002]

2. Description of the Related Art A liquid discharge apparatus discharges a liquid such as ink as droplets from a discharge port provided in an orifice plate of a liquid discharge head and attaches it to a recording medium such as a recording paper to form print recording and image formation. Droplets are ejected from ejection openings by driving ejection energy generating elements such as piezo elements and electrothermal conversion elements provided in the liquid ejection head based on drive signals corresponding to recording information and image information. I do.

As an ejection energy generating element, specifically, an electro-thermal conversion element (heating element) that generates heat when energized in accordance with a recording signal is used, and heats the liquid in a liquid flow path to generate a liquid. A bubble is formed by causing a state change to occur, and a liquid is discharged based on a volume change at the time of the formation of the bubble. This type of discharge energy generating element uses a thin film forming technology in the semiconductor field on a silicon substrate. It is formed using.

[0004] Such a liquid ejection head is generally
An element substrate on which a plurality of ejection energy generating elements are arranged,
It is composed of a top plate that covers the upper part,
An orifice plate having a plurality of liquid flow paths (nozzle rows) and discharge ports respectively facing the discharge energy generating elements on the element substrate, a liquid chamber for supplying liquid to each liquid flow path, and supplying a liquid to the liquid chambers And a liquid supply port.

The orifice plate is a sheet member having a size of several tens μm to several hundreds μm, and the sheet member has a large number of fine holes as discharge ports.
As a method for efficiently forming these fine holes with high precision, laser processing, electroforming, precision press processing, precision molding, and the like are used.

On the other hand, the liquid flow path is formed by a groove having a width of several tens μm and a depth of several tens μm.
Are arranged at a small pitch. Precision molding such as injection molding, transfer molding, compression molding, extrusion molding, casting, ceramic injection, metal molding, etc., so that such fine grooves are arranged with high precision facing the ejection energy generating element, Laser, Y
It is manufactured by fine processing such as AG laser, anisotropic etching of silicon, and a semiconductor thin film forming technique such as photolithography.

[0007] The top plate can be formed by the above-mentioned various kinds of precision processing. Among them, the method of precision molding is very effective in that members can be manufactured at low cost and that a complicated shape can be easily formed. Yes, it is used in the manufacture of various types of top boards.

In a manufacturing method for forming a top plate by precision molding, there are a case where the nozzle row is transferred and formed from a mold at the time of molding, and a case where the nozzle row is processed and formed by excimer laser processing after the formation of the top plate. Generally, the density of the liquid flow path is 400 dp
In the case of a top plate having a length of i or less, or a top plate having a total length of the liquid flow passage of several tens mm or less, the liquid flow passage is formed by molding,
On the other hand, in the case of a high-density type top plate having a liquid flow path of 600 dpi or more, or a long type top plate having a liquid flow path total length of 100 mm or more, the liquid flow path is formed by excimer laser processing. .

As the molding resin material, polysulfone,
Polyether sulfone, polyphenylene sulfide, modified polyphenylene oxide, polypropylene,
A resin material having excellent ink resistance such as polyimide and liquid crystal polymer (LCP) is used.

In the molding of the top plate, which is a minute component, it is required that the thin portion of the orifice plate can be filled and the minute portion of the liquid flow path wall can be transferred stably. Difficulty is increasing,
It is very difficult to stabilize molding accuracy and maintain its quality.

[0011] Injection molding mainly consists of two steps, an injection step and a dwelling step. In the injection step, the resin must flow through the entire interior of the mold as quickly as possible before cooling and solidifying. However, in this injection step, the resin flow is stagnant in places where the flow of the resin is stagnant, minute corners and minute parts, etc., so that the resin is insufficiently filled. The unfilled portion is completely filled because the resin inside the mold is pushed in another step by the holding pressure that is sometimes applied. Therefore, the shape of the molded product and the mold structure must be established so that such a holding pressure efficiently acts on the fine shape region.

In the conventional top plate, by disposing a fan gate 150 as shown in FIG. 10 on the back surface of the top plate 110, resin is injected from a wide area on the back surface of the top plate, and resin is spread over the entire top plate. Is considered to flow efficiently. In addition, the selection of the fan gate narrows the area near the gate, so the resin that passes through this area actively generates heat due to shearing and improves the fluidity of the resin. Can be done.

The orifice plate may be formed integrally with the top plate or may be formed separately from the top plate. The configuration of both top plates is appropriately selected depending on the overall component configuration, the configuration of the assembling apparatus, the laser processing method, and the like, but in any case, an advanced fine molding technique is required.

FIG. 11 shows a schematic configuration of such a liquid discharge head.
Shown in In FIG. 11, the liquid ejection head includes an element substrate 100 on which a number of ejection energy generating elements (heating elements) 101 are disposed, a liquid chamber 111 joined to the element substrate 100 and containing a liquid, and a liquid flow path ( A liquid supply port 114 communicating with the liquid chamber 111 is provided above the liquid chamber 111 at the top of the liquid chamber 111.
Are formed.

An orifice plate 115 having a discharge port 116 for discharging liquid is formed integrally with the top plate 110 or in front of the liquid flow path 112.
The discharge port 116 is connected to the liquid flow path 112 by being joined or engaged with the liquid passage 112.

The element substrate 100 is adhered and fixed to a supporting substrate (base plate) 120 with an adhesive 122 or the like. The top plate 110 is connected to the heating element 101 serving as a discharge energy generating element provided on the element substrate 100. Board 110
The orifice plate 115 is aligned with the liquid flow path 112 of the
Is arranged so as to hang forward on the front end face of the camera. Also, the top plate 11
The zero liquid chamber 111 receives liquid from a liquid storage tank (not shown) via a liquid supply port 114.

In such a liquid discharge head, the liquid flow path wall 113 and the element substrate 100 are joined to form the liquid flow path 11.
When forming the liquid channel 2, if the liquid channel wall 113 and the element substrate 100 are joined with a bonding agent such as a sealant or an adhesive,
There is a possibility that these bonding agents may enter the inside 12, change the shape of the liquid flow channel 112, or block a part of the liquid flow channel 112. Therefore, bonding is performed by mechanically pressing at least the liquid flow path wall portion. The configuration will be described below.

The positioning of the element substrate 100 and the top plate 110 in the liquid discharge direction is performed while the front end of the element substrate 100 is abutted against the orifice plate portion 115.
The element substrate 100 and the top plate 110 are joined together, and then the claws 131 provided at the lower ends of both ends of the pressing spring 130 are inserted into the holes 121 provided in the support substrate 120, and the bent portions 13 are formed.
2 is hooked on the lower surface of the support substrate 120. Accordingly, the presser spring 130 linearly presses the upper side of the liquid flow path wall 113 of the top plate 110, so that a mechanical pressure can be applied to the contact portion of the top plate 110. Therefore, the liquid flow path wall 113 of the top plate 110 and the element substrate 100 are brought into close contact with each other by the pressing force of the pressing spring 130.

However, the liquid pressure wall 113 and the element substrate 100 can be brought into close contact with each other by mechanical pressing as described above, but the pressing force acts on other joints such as the outer wall of the liquid chamber 111. And it becomes difficult to ensure close contact. For this reason, a sealant is often used for these portions to enhance the airtightness of the liquid discharge head. Therefore, the sealant is used at the joint between the members that come into contact with the liquid in the liquid ejection head to prevent the liquid from leaking.

[0020]

By the way, in a liquid ejecting apparatus as an output device such as a personal computer terminal, a copying machine, a facsimile, etc., a resolution equivalent to a silver halide film will be obtained in the future, and further, a laser beam printer will be required. In the liquid ejection head, it is required to increase the resolution of the liquid discharge head by increasing the arrangement pitch of the liquid flow paths and increase the arrangement length of the discharge ports. Therefore, it is necessary to discharge the liquid at a higher speed.

However, in a conventional molding method in which a fan gate is provided on the back surface of a top plate (see FIG. 10),
Since the resin injected from the wide area on the back surface of the top plate reaches the liquid flow path wall section after passing through the shape forming area such as the liquid chamber section and the liquid supply section on the upstream side, the pressure loss in the intermediate path is reduced. There is a possibility that the injection pressure and the holding pressure are not easily transmitted to the liquid flow path wall. Therefore, it is difficult to reliably fill all the liquid flow path walls with a top plate having a high-density liquid flow path or a long plate having a long liquid flow path arrangement length. This is a molding method that is not suitable for the top plate of the above-described embodiment.

Generally, several μm is provided on the lower surface of the liquid flow path wall of the top plate.
A degree of warpage has occurred, and the upper surface of the liquid flow path wall is pressed downward by linear pressing of the pressing spring, thereby correcting the warpage of the lower surface of the liquid flow path wall while maintaining the lower surface of the liquid flow path wall as an element. Adhered to the substrate. When the top plate is brought into close contact with the element substrate by such mechanical pressure, internal stress and internal distortion are generated around the liquid flow path wall, and the orifice plate follows the influence of the distortion. And warp.
At this time, in the orifice plate portion, the orifice plate surface portion is warped in the liquid discharge direction, or the orifice plate surface is inclined upward or downward, and the relative orientation of the plurality of discharge port arrays arranged on the orifice plate is determined. The relative position will change. If the amount of change in the relative position of the ejection port array becomes large, the landing accuracy of the liquid droplets deteriorates, and the print quality deteriorates.

The deformation factors of the orifice plate portion include a strain generated by such mechanical joining of the top plate and an internal strain generated by an internal stress caused by curing shrinkage of the molding resin. As a matter of course, the deformation of the orifice plate during molding tends to increase as the arrangement length of the discharge ports increases.

As a means for reducing the internal strain of the orifice plate caused by the above-mentioned close contact, there is a method of forming the top plate from a material having a large elastic modulus to improve the rigidity of the top plate. However, when the rigidity of the top plate is increased, it is difficult to correct the molding warpage on the lower surface of the liquid flow path wall, which causes a poor adhesion to the element substrate. On the other hand, there is a method of increasing the linear pressing force of the pressing spring, but increasing the linear pressing force increases the internal distortion of the top plate.

In the case where the liquid flow path wall and the element substrate are not sufficiently adhered to each other, the adjacent liquid flow paths among the plurality of liquid flow paths formed by joining the element substrate and the liquid flow path wall may be used. There will be a gap with the substrate. As a result, the discharge energy due to the liquid inertia force generated from the bubble generation process on the heating element is dispersed to the adjacent liquid flow path, and the discharge of the liquid becomes unstable during print recording and image formation. And the droplets are distorted. In addition, when a recording signal is applied, the liquid is not ejected from the ejection port to which the liquid is to be ejected, and the liquid is ejected from the adjacent ejection port, which may cause print disturbance, which may lead to deterioration of image recording quality. .

In view of the above, in order to develop an inexpensive liquid ejection apparatus capable of high-speed, high-quality recording, a mold and a molding method that can be developed on a top plate having a high-density liquid flow path or a long top plate have been developed. It is necessary to propose and overcome the conventional problems as described above.

Specific means for solving the conventional problems are that the flatness of the lower surface of the liquid flow path wall is good, that the warpage and deformation around the discharge port are small, and that the rigidity of the top plate is appropriately large. From these developments, to reduce the internal distortion generated in the top plate due to close contact with the element substrate,
This is to maintain the arrangement and orientation of the discharge ports with high precision.

On the other hand, as for the molding resin, selecting a material having high precision and excellent dimensional stability is an important factor that is indispensable for improving the precision thin wall molding technique. In order to overcome the weaknesses of the top plate, there is a limit in molding using a pure material as before, so the top plate is molded using a molding material that is filled with filler etc. and has enhanced physical properties Such measures are required.

However, molding a top plate from a resin filled with a filler or the like has the following problems.

(1) Problems Related to Laser Processing When the orifice plate is formed of resin, the fine holes provided therein are generally formed by ablation using an excimer laser. However, in the excimer laser processing, the filler portion is not ablated, so that there is a possibility that the filler remains in a protruding shape on the inner surface of the fine hole or the filler is dropped from the surface to form a concave portion, and the inner surface of the fine hole is smooth. No longer
This may cause liquid ejection failure.

(2) Problems Related to Mold Production The liquid flow path wall of the top plate has a complicated and minute shape, and a mold piece for transferring this portion is required to have extremely high dimensional accuracy. Since it cannot be easily machined with a general machine tool, it is manufactured using a special precision machining machine and a special material and spending a long time. This is the main factor that makes the production cost of the top plate forming die expensive. Furthermore, in the molding process, this mold piece rubs against the molten resin at the time of injection and rubs against the molded product at the time of release, so that when the top plate is formed from a material containing a filler or the like, the wear of the mold piece becomes faster. Therefore, the durability of the mold is reduced and the productivity of the top plate is reduced.

(3) Problems related to the fluidity of the material In forming the top plate, a material grade having good fluidity is selected in order to surely transfer a fine portion. However, generally, when a filler is contained in a resin, fluidity tends to deteriorate, which is disadvantageous in molding in a form of filling a thin thick portion or a fine portion.

(4) Problems that the filler hinders the flow and filling of the resin The width of the liquid flow path wall is as fine as several μm to several tens of μm, and filler particles such as fibers and beads are formed on the liquid flow path wall. May be larger than the thickness. Therefore, when the top plate is formed of the resin containing the filler, not only the filler is not transferred into the liquid flow path wall, but also the filler stagnates in a state of being bridged at the entrance of the groove portion and flows from the rear. The flow of the molten resin is blocked or the flow is disturbed. Also, when molding with a resin containing a filler, the filler may precipitate on the surface of the molded product,
The filler deposited on the surface may rub against the mold at the time of mold release, and may be missing from the surface layer of the molded product. Furthermore, since the filler is not filled in the liquid flow path wall, the performance improvement effect of the filler is reduced in the liquid flow path wall.

On the other hand, there is a method of forming a top plate with a resin containing an ultrafine powdery filler of about 1 μm to several μm, but the ultrafine powdery filler is uniformly dispersed in a resin base resin. It is very difficult to achieve this, and it is extremely difficult to supply a stable material. In addition, in order to uniformly disperse such a fine powder filler in the base resin, a special dispersion technique and surface treatment of the fine powder filler with a silane coupling agent or the like are required. Is very expensive.

As described above, when the top plate is molded from a resin whose physical properties are enhanced by the inclusion of a filler, the molding accuracy is improved, but the laser processing is hindered, the quality of the molded product is reduced, and the durability of the mold is reduced. It is not always an effective means because it involves an adverse effect such as an expensive molding material.

Therefore, it is difficult to improve the molding accuracy of the top plate, the flatness of the lower surface of the liquid flow path wall, the rigidity of the top plate, and the like by the conventional molding method. Has been an issue.

Next, problems in the use environment and storage environment of the liquid discharge head will be described.

If the temperature fluctuation of the environment in which the liquid discharge head is used becomes large, the individual components constituting the liquid discharge head may expand or contract in volume, which may cause a relative displacement of the head joint. . In particular, in the case of a long head, such a relative positional deviation is accumulated in the liquid flow path arrangement portion, so that a large relative positional deviation occurs in the liquid flow paths at both ends.

The liquid flow path formed by the close contact between the top plate and the element substrate has a very fine pitch of several tens of μm. Therefore, if the relative displacement between them becomes large, the liquid discharge performance is adversely affected. become.

Further, since the material of the member forming the element substrate and the material of the member forming the top plate are different, a force is exerted on both members to move their relative positions. In other words, the element substrate and the top plate individually undergo volume changes due to the internal stress generated from thermal expansion in response to temperature fluctuations, so the bonding interface where the liquid flow path wall and the heating element face each other may cause relative displacement. And

On the other hand, as described above, the liquid flow path wall is mechanically pressed, and the pressing force causes a frictional force to act between the liquid flow path wall and the element substrate. The relative displacement between the liquid flow path and the element substrate is prevented by the mechanical strength of the wall itself.

However, since the effect of such mechanical pressing force is reduced at the tip of the discharge port, the position is extremely small between the tip of the discharge port, the liquid flow path wall, and the element substrate, but the relative positional displacement is small. May occur.

For example, in a liquid discharge head having a discharge port arranged at a resolution of 600 dpi, the width of the front end of the liquid flow path wall is as small as about 7 to 10 μm. The force and mechanical strength will decrease. That is, the degree of the influence of the relative positional deviation as described above increases as the density of the nozzle rows increases, and it becomes difficult to suppress the relative positional deviation.

As described above, in the case of a top plate or a long top plate in which the liquid flow paths are arranged at a high density, even if the thermal expansion is slight, the discharge ports at both ends may have a large relative displacement. are doing.

In order to suppress the relative displacement, there is a method of increasing the linear pressing force of the pressing spring to increase the frictional force of the liquid flow path wall contact surface, but a method of increasing the linear pressing force of the pressing spring. As described above, the internal distortion of the top plate increases, which is not very advantageous. Furthermore, in a high-temperature environment, the liquid flow path wall receives the action of thermal stress and the pressure of the presser spring, so if the liquid flow path wall cannot withstand these forces, the liquid flow path wall will undergo plastic deformation such as buckling or bending. Would be.

As described above, in the conventional structure of the top plate formed by molding, it has been difficult to form a top plate having a high-density nozzle or a long top plate by fine molding due to the influence of thermal expansion.

As described above, as the resolution and the printing speed of the liquid ejecting apparatus in the future increase, the resin material applicable to the top plate is considerably limited. However, it is very difficult to achieve both the molding accuracy and the performance required by the top plate.

Therefore, the present invention improves the filling property of the liquid flow path wall and the thin portion of the orifice plate and the like in order to achieve a high resolution technology and a high-speed printing technology in a future liquid discharge apparatus. The aim is to establish the molding technology corresponding to the top plate, and to improve the overall performance of the orifice by improving the top plate structure, molding accuracy and dimensional stability of the top plate, molding conditions, molding die structure, etc. Provided is a liquid discharge head capable of reducing the deformation of the plate and the warpage of the lower surface of the liquid flow path wall, and by arranging the discharge ports with high precision, improving the landing accuracy of the liquid and improving the print quality. The objective is to overcome the weaknesses in performance, such as thermal expansion and rigidity, which were issues in the conventional top plate.Furthermore, with a high-density nozzle, high speed and high image quality can be obtained. One it is an object to provide a liquid discharge head can be inexpensively manufactured.

[0049]

In order to achieve the above object, a liquid discharge head according to the present invention comprises: an element substrate provided with discharge energy generating elements for applying discharge energy to a liquid corresponding to a plurality of liquid flow paths; A liquid passage groove corresponding to the plurality of liquid passages, an orifice plate provided with discharge ports for discharging liquid in communication with one end of the liquid passage groove, and an orifice plate other than the liquid passage groove. A liquid chamber that communicates with the end and supplies the liquid to the liquid channel; and a liquid supply port that supplies the liquid to the liquid chamber. The liquid channel, the orifice plate, the liquid chamber, and the liquid supply port are provided. In a liquid discharge head that forms the liquid flow path by joining a top plate member and the element substrate that are integrally formed, the top plate member is provided in a vicinity of the liquid flow channel and the discharge port. Orifice including the discharge port as a boundary surface A first base composed of a lower half of the port and the liquid flow channel, a second base composed of an upper half of the orifice plate not including the discharge port, the liquid chamber, and the liquid supply port; The first substrate and the second substrate are joined and integrated by two-color molding in which the first substrate is molded by primary molding and the second substrate is molded by secondary molding.

In the liquid discharge head according to the present invention, it is preferable that a gate for primary forming the first base is disposed on the boundary surface above the liquid flow channel, and that one or more pins are provided. Preferably, it is a point gate.

In the liquid discharge head according to the present invention, it is preferable that a relay portion for connecting the first base and the boundary surface is provided between the gate for primary molding and the boundary surface.

In the liquid discharge head according to the present invention, a gate for secondary forming the second base is disposed on a side surface in the longitudinal direction of the top plate member, and the secondary molding resin is supplied to the liquid flow of the top plate member. It is preferable to be configured to flow in the road arrangement direction.

In the liquid discharge head according to the present invention, it is preferable that the second substrate is formed of a material having a smaller linear expansion coefficient than a material injected into the first substrate, and the volume of the second substrate is reduced. Preferably, the volume is at least four times the volume of the first substrate.

In the liquid discharge head of the present invention, it is preferable that the thickness of the first substrate is 1 mm or less.

In the liquid discharge head of the present invention, the first base is preferably formed of a transparent member, and is preferably formed of polysulfone.

In the liquid discharge head of the present invention, the second substrate is preferably formed of a composite material filled with fillers such as fibers and beads, and further, a base of the material injected into the second substrate. The resin is
It is preferable that the material is the same as the base resin of the material injected into the first base.

In the liquid discharge head according to the present invention, a rib, a bellows, a boss, a seat, or a rectangular irregular row is formed on a part of a boundary surface between the first base and the second base.
It is preferable that the projection of the first base is configured to enter the recess of the second base, and the projection of the second base is configured to enter the recess of the first base.

[0058]

According to the liquid discharge head of the present invention, the top plate member has the boundary near the upper portion of the liquid flow channel and the discharge port.
Divided into a first base including the lower half of the orifice plate including the periphery of the discharge port and the liquid flow channel, and a second base including the upper half of the orifice plate, the liquid chamber, and the liquid supply port. The first base and the second base are formed and joined together by two-color molding in which the first base is formed by primary molding and the second base is formed by secondary molding. It becomes a simple shape, the flow and orientation of the injected resin are stable, no extra pressure loss occurs during the flow, the molding accuracy and filling of the top plate can be improved, and various resins and ceramics can be used. By performing two-color molding (or multi-color molding) by combining metals, fillers, and the like, it is possible to form a high-precision and multifunctional top plate that cannot be realized by molding a single material.

Further, since the orifice plate is formed by being divided into two steps of a lower half part and an upper half part including the peripheral part of the discharge port, the area where the thin part is dominant in one molding step becomes small. As compared with the case where the entire orifice plate is molded at one time, the filling of the thin and thick portion becomes easier, and the moldability can be remarkably improved.

By forming the top plate from a composite material of different materials, the molding resin of the second substrate can be molded using various materials, and the two can be integrally joined by two-color molding. Thereby, improvements can be achieved in terms of rigidity such as elastic modulus and performance such as thermal expansion.

Further, the primary molding gate for molding the first base is disposed on the boundary surface near the upper portion of the liquid flow channel with a pinpoint gate, so that the distance between the gate and the liquid flow channel is linear and shortest. Molded resin injected from the gate is connected by the path and flows smoothly to the liquid flow path section directly below the gate, and the resin injection pressure acts directly on the liquid flow path wall Since the holding pressure in the pressure holding step is efficiently applied toward the liquid flow path wall, the filling property of the liquid flow path becomes very good. Similarly, since the thin portion of the orifice plate is also disposed at the shortest distance from the gate, the injected resin flows through the thin portion of the orifice plate without causing a large pressure loss on the way. The thin portion of the orifice plate is reliably filled.

Therefore, even in the case of molding a top plate in which the discharge ports, which have conventionally been difficult in injection molding, have a high density of 600 dpi or more, the transfer of the liquid flow path wall portion can be easily realized. Even in the case of a long top plate having an ultra-thin orifice plate of 20 μm to 50 μm and having a liquid flow path arrangement length of 100 mm or more, the installation position and the installation quantity of the primary molding pinpoint gate can be appropriately increased. For example, the thin portion of the orifice plate and the fine portion of the liquid flow path wall can be filled well regardless of the length of the top plate.

Further, a gate for secondary molding is arranged on the side surface in the longitudinal direction of the top plate, and the second substrate is molded with a resin containing a fibrous filler. The fibers of the filler will be oriented in the direction of the liquid flow path, and the second base will have the rigidity and thermal expansion characteristics of the secondary molding material. The molded top plate obtains rigidity that cannot be obtained by molding with a single material, and the thermal expansion characteristics in the liquid flow path arrangement direction are remarkably improved.

Further, by forming ribs, bellows, bosses, seats, or rectangular irregularities on the boundary surface between the first base and the second base, the bonding area between the first base and the second base can be increased. And the bonding between the two can be further strengthened. Furthermore, in the case where a resin having a small coefficient of thermal expansion is used for the second base, even if the top plate is placed in an environment with a large temperature change and the first base attempts to change the volume,
Since the second base is physically prevented from being formed by the irregularities on the boundary surface, the change in volume of the first base can be more effectively suppressed. Further, if the uneven shape of the boundary portion is formed such that both are undercut in the peeling direction, the first base and the second base are formed of different materials,
Even when the bonding strength is low, the two can be integrated, and the material properties of the second base can compensate for the weakness of the material properties of the first base.

[0065]

Embodiments of the present invention will be described below with reference to the drawings.

A first embodiment of the liquid discharge head according to the present invention will be described with reference to FIGS.

FIGS. 1 and 2 are a schematic perspective view showing an example of the configuration of the liquid discharge head of the present embodiment and a schematic perspective view exploded and shown. FIGS. 3 and 4 show the present embodiment. It is the schematic perspective view and schematic cross section which show an example of the top plate formed by the two-color shaping | molding in an example. 5 to 8
6 shows an example of two-color molding of a top plate in the present embodiment, FIG. 5 is a schematic perspective view showing a mode of primary molding, and FIG.
FIG. 7 is a schematic perspective view showing a state after gate cutting after primary molding, FIG. 7 is a schematic sectional view showing a mold configuration of primary molding, and FIG. 8 is a schematic perspective view showing an aspect of secondary molding. FIG.

First, a first example of the liquid discharge head according to the present invention will be described.
The configuration of the embodiment will be described with reference to FIGS.

1 to 4, reference numeral 1 denotes an electrothermal transducer (heat generating element) 1a as an ejection energy generating element for ejecting a liquid such as ink, and wiring for supplying power to the electrothermal transducer 1a. Is an element substrate made of a silicon substrate formed by a silicon film forming process, 2 is a wiring substrate provided with wiring for the element substrate 1 and electrical contacts for the liquid ejection device main body,
A PWB substrate having a wiring pattern formed of copper or nickel on a glass epoxy substrate, a TAB film having a wiring pattern formed on a flexible film, or the like is used. The element substrate 1 and the wiring substrate 2 are electrically connected by, for example, wire bonding.

Reference numeral 3 denotes a support substrate (base plate) formed of aluminum or the like. The support substrate 3 also functions as a heat sink for radiating and cooling the heat of the element substrate 1 generated by driving. The element substrate 1 and the wiring substrate 2 are joined on a support substrate 3, the element substrate 1 is die-bonded on the support substrate 3, and the wiring substrate 2 is adhered on the support substrate 3 with an adhesive or the like.

Reference numeral 5 denotes a top plate forming a liquid flow path.
The orifice plate 6 is formed with a desired number of discharge ports 6a for discharging liquid to the recording medium, and a concave groove is formed on the lower surface of the top plate 5 as a liquid flow path communicating with the discharge ports 6a. A plurality of nozzles (nozzle rows) 7, a liquid chamber 8 formed in a concave shape on the lower surface of the top plate 5 and serving as a sub-tank for supplying liquid to the nozzle rows 7, and a liquid from a liquid storage tank (not shown) to the liquid chamber 8 And a liquid supply port 9 for supplying the liquid.

As shown in detail in FIG. 4, the orifice plate 6 has the thinnest portion 6e around the discharge port 6a,
The thinnest portion has a thickness of 0 μm, and the rear surface portion of the thinnest portion facing the orifice plate surface is formed parallel or substantially parallel. If the thickness of the peripheral portion 6e is increased, the diameter of the hole may be reduced due to laser characteristics.
The hole area of the discharge port 6a on the surface side of the orifice plate becomes small, so that the liquid discharge amount decreases and it becomes difficult to discharge the liquid stably. In addition, since the laser processing time is long and the processing accuracy is lowered, the laser processing layer is generally formed with a very thin thickness of about 20 μm to 70 μm.

In the nozzle row 7, the thickness of the tip of the groove wall, which is the contact surface with the element substrate 1, is several μm to several tens μm, and the groove depth is several tens μm to several hundreds μm. It is formed with dimensions.

As described above, since the orifice plate 6 is thin and the nozzle row 7 has a fine shape, the top plate can be formed using a molding material having extremely high fluidity by a high-speed injection molding machine. It has been done.

Reference numeral 10 denotes a heating element 1 on the element substrate 1.
is a pressing spring for bringing the nozzle row 7 on the top plate 5 into close contact with the nozzle row 7. After the alignment is adjusted so that the relative position between the heating element 1a and the nozzle 7 is completely matched, the pressing spring 10 is moved to the nozzle row. 7 to the top plate 5
Press. That is, a substantially U-shaped bent portion 10a provided at both ends of the holding spring 10 is provided with the hole 3 provided in the support substrate 3.
a, and the claw portion 10 b is hooked on the lower surface of the support substrate 3. As a result, the linear pressure generating portion 10 of the pressing spring 10
c can linearly press the spring receiving portion 5a of the top plate 5 to apply mechanical pressure toward the element substrate 1 to the groove wall lower surface 7a of the nozzle row 7. Due to the pressing of the pressing spring 10, the lower surface 7a of the groove wall of the nozzle row 7 comes into close contact with the element substrate 1, whereby each nozzle 7 is completely partitioned.

The orifice plate 6 is used for the element substrate 1.
Are arranged like a forward hang on the front end face 1b of the device, the positioning of the element substrate 1 and the top plate 5 in the liquid discharge direction is performed as follows.
This is performed so that the front end face 1b of the element substrate 1 abuts against the back face 6b of the orifice plate 6.

In general, the top plate 5 is warped due to curing shrinkage during molding, and the pressing force of the pressing spring 10 as described above is applied to the back surface 6 b of the orifice plate 6 and the element substrate 1.
Since it does not act in the direction of joining the front end surface of the device, a minute gap is formed between the two surfaces after the top plate 5 and the element substrate 1 are joined. Further, since a small step is provided between the lower surface 8c of the outer wall of the liquid chamber 8 and the lower surface 7a of the groove wall of the nozzle row 7, after the top plate 5 and the element substrate 1 are joined, the outer wall lower surface 8c of the liquid chamber 8 A gap of several μm to several tens μm is formed between the element substrates 1.

Therefore, in order to prevent the liquid from leaking from such insufficiently adhered portions and gaps, a sealing agent such as silicone is injected into the entire bonding interface between the element substrate 1 and the top plate 5. Filling the gap. Specifically, a gap between the back surface 6b of the orifice plate 6 and the front end surface 1b of the element substrate 1, a gap between the back surface 6b of the orifice plate 6 and the front end surface 3b of the support substrate 3, the top plate 5 and the element substrate 1, Sealing of these gaps and joints is performed within a predetermined range by the capillary force generated between the gaps between the members and the sealant. The sealing is performed by devising the shape of the member and controlling the viscosity of the sealing agent so that the sealing agent does not flow outside the range.

However, the back surface 6b of the orifice plate 6
The gap between the substrate and the front end face 1b of the element substrate 1 is very small, and is the most difficult part to inject the sealant. It is necessary to visually confirm that the sealant is filled in a desired range. There is. If the orifice plate 6 is transparent, the filling state of the sealant can be confirmed from the front surface of the orifice plate 6, so that the orifice plate 6 is preferably transparent.

Next, the configuration of the top plate formed by two-color molding will be described with reference to FIGS. The top plate 5 is divided into two bases 21 and 22 with a boundary surface 23 provided near and above a liquid passage portion to which the nozzle row 7 and the discharge port 6a are connected, and the orifice plate 6 also has a boundary. The orifice plate lower half 6c and the orifice plate upper half 6d are divided and formed with the surface 23 as a boundary. The first base 21 is provided with the lower half 6 of the orifice plate.
The second base 22 is composed of an upper half 6d of an orifice plate, a liquid chamber 8, a liquid supply port 9, a spring receiving portion 5a, and an outer peripheral portion of a top plate. The first substrate 21 and the second substrate 22 are joined and integrated by two-color molding in which the first substrate 21 is formed by primary molding and the second substrate 22 is formed by secondary molding. In other words, the upper and lower halves 6c of the orifice plate 6, which are formed separately,
6d is also integrated by two-color molding.

The first base 21 is composed of the lower half 6c of the orifice plate and the fine portion of the nozzle row 7, and is formed of a material having good fluidity and suitable for fine forming, such as polysulfone, polyethersulfone, or the like. Is done. These materials have conditions necessary for the orifice plate, such as being transparent and excellent in laser workability.

The peripheral portion 6e of the discharge port of the lower half portion 6c of the orifice plate has a thickness of several tens of μm and is the thinnest portion in the first base 21. When this region is widened, the filling property of the resin becomes large. It will get worse. For this reason,
The thickness of the lower half 6c of the orifice plate is formed to have a smooth gradient so as to increase as it goes downward from the peripheral portion 6e of the discharge port. This aims to improve the molding accuracy by avoiding irregular thickness fluctuations, reduce the pressure loss of the flowing resin, improve the filling property, and further increase the strength of the orifice plate. .

Since the first base 21 is formed of a pure and transparent material (polysulfone, polyethersulfone, or the like) as described above, the sealing performed after the top plate 5 and the element substrate 1 are brought into close contact with each other. In the stopping step, it is possible to easily observe the sealing condition at each sealing portion.

Further, since the orifice plate 6 is formed into two parts and is formed by being divided into two steps of the first base and the second base, the orifice plate 6 is formed by one molding as in conventional injection molding. Compared to the case where it is formed, the area of the thin thick part allocated to one molding process is narrower, the difficulty in filling the resin is reduced, the productivity is significantly improved, and the molding accuracy is also improved Will do.

Therefore, dividing the top plate 5 into the first base 21 and the second base 22 and joining them by two-color molding is to improve the molding accuracy of the top plate 5. It is a very effective means. Then, even if both are made of exactly the same material, if they are divided and formed by multi-color molding, the individual substrates are formed with high accuracy, and the forming accuracy of the completed top plate 5 is significantly improved. Further, since both are joined at the time of molding, there is no need for a joining step such as assembly and bonding, and therefore, the productivity is excellent.

On the other hand, the second substrate 22 does not have a finely shaped portion and has a small thin-walled region, so that it does not require the transfer accuracy and dimensional accuracy of the first substrate 21. In addition, since the outer peripheral portion of the second base 22 plays the role of the housing of the top plate 5, the mechanical properties of this portion greatly affect the performance of the entire top plate. From these points, it is only necessary to select a molding material for the second substrate with emphasis on mechanical properties.

Therefore, if the second base 22 is formed of a resin containing a filler, the second base 22 and the nozzle row 7
The elastic modulus of the peripheral portion of the top plate 5 increases, and accordingly, the top plate 5
The overall rigidity will increase. Further, the rigidity of the orifice plate upper half 6d is improved to improve the rigidity of the entire orifice plate.
This reduces the distortion of the orifice plate surface caused by mechanical close contact with the orifice plate.

Therefore, the combination of increasing the molding accuracy of the first base 21 and increasing the rigidity of the second base 22 allows
The flatness of the lower surface 7a of the groove wall of the nozzle row is improved, and the internal distortion of the top plate 5 and the orifice plate 6 is significantly reduced. With these, the ejection ports 6a are arranged with high precision, and a liquid ejection head that has excellent liquid landing accuracy and can perform stable liquid ejection can be manufactured.

Further, since the second substrate 22 has no finely shaped portion and has a small number of thin and thick regions, the durability of the mold can be neglected. Therefore, the filler to be filled in the secondary molding resin for the second substrate 22 is used. Will be able to select various materials. Therefore, for the second base 22, it is only necessary to select a material with emphasis on the rigidity surface, and thereby it is possible to optimize the rigidity of the top plate.

Further, magnesium alloy, SUS, iron,
If the second base 22 is formed by MIM (metal injection molding) using a material such as steel or ceramic injection using ceramics, the top plate 5 can obtain rigidity that cannot be obtained by resin molding. Become like

As described above, the nozzle row 7 is generally made of a resin such as polysulfone or polyethersulfone because of molding, sealing, laser processing, and the like. As a result, there is a limit to the low thermal expansion of the first base 21. Therefore,
If the second base member 22 is formed of a material that is resistant to thermal expansion, the formed portion of the second base member 22 structurally compensates for the weak point of the thermal expansion of the formed portion of the first base member 21 and the entire top plate 5. Will be able to do it.

In the orifice plate 6, the boundary surface 2
3 is provided near the upper part of the liquid passage (the portion where the nozzle row 7 and the discharge port 6a are connected), as shown in FIG. 4, so that the second base 22 is formed of a low thermal expansion material. In addition, even if the liquid passage attempts to cause thermal expansion in the direction in which the liquid passages are arranged at the time of environmental change, the second base 22 itself acts to prevent such expansion due to its rigidity and thermal expansion characteristics. As described above, by forming the second base member 22 from the low thermal expansion material, the nozzle row 7 and the discharge port 6a may individually fluctuate or the nozzle row 7 and the discharge port 6a may be changed under an environment where the temperature fluctuates drastically. The relative orientation does not change.

When the molding resin of the second base 22 is made to contain a filler to reduce the coefficient of linear expansion of the second base 22, the bonding property between the base resin of the second base 22 and the resin of the first base 21 is reduced. Becomes important. Therefore, it is preferable that a material having good bonding compatibility between the second base 22 and the first base 21 is selected. For example, when the first base 21 is polysulfone, the second base 22 is formed by adding carbon to the base resin polysulfone. When a filler such as a fiber or a glass fiber is filled, the base resin of the two becomes the same, so that the bonding at the boundary surface becomes good during the two-color molding.

When the second base member 22 is formed of a resin containing a filler, the second base member 22 has an effect of improving the molding accuracy. That is, when the filler is filled, the curing shrinkage of the resin at the time of molding is reduced by the filler, so that the molding accuracy of the second base 22 is inevitably improved. Thus, if the molding accuracy of both the first base 21 and the second base 22 is improved,
The top plate 5 completed by joining the two is naturally finished into a high-precision molded product.

Next, a mold structure and a molding method for two-color molding of the top plate of this embodiment will be described with reference to FIGS.

5 to 7, 31 is a pinpoint gate for primary molding, 32 is a relay section, 33 is a secondary sprue for primary molding, 34 is a runner for primary molding,
The primary molding resin is injected into the molding frame of the first base 21 from the boundary surface 23 via the four pinpoint gates 31 and the relay portion 32. An example of such a primary molding die is shown in FIG. 7, in which 36 is a fixed mold plate, 37 is a movable mold plate, and 38 is a movable slide piece.

In FIG. 8, 41 is a side gate for secondary molding, 42 is an intermediate gate for secondary molding, 43 is a secondary sprue for secondary molding, and the secondary molding resin is a side gate 41. The second base 2 from one side surface 5b of the top plate 5
2 is injected into the molding frame.

In the primary molding, as shown in FIGS. 5 to 7, a resin injected from a screw type cylinder (not shown) is injected into the mold from a primary sprue for primary molding (not shown), and the primary molding is performed. The runner 34 passes through the secondary sprue 33 for primary molding. And the primary molding runner 3
The resin branched in four parts is filled into the molding frame of the first base 21 via the four pinpoint gates 31 and the relay part 32.

Therefore, the relay portion 32 is a passage serving as a bridge between the pinpoint gate 31 and the boundary surface 23 of the first base 21. If the boundary surface 23 is provided at a height equal to or higher than the height of the liquid chamber upper surface 8a, the relay portion 32 becomes unnecessary. In this case, however, the area occupied by the second base member 22 that can be molded with a resin having high mechanical strength. And the rigidity of the entire top plate is reduced, which is not a very preferable configuration. On the other hand, in a top plate configuration in which the boundary surface 23 is provided at a position lower than the liquid chamber upper surface 8a, the pinpoint gate 31 can be directly disposed on the boundary surface 23. Since the fixed side mold plate forming the gap becomes thinner and the mold strength decreases,
Such a gate structure is not a very preferable configuration.

Due to the above-described factors, the relay portion 32 transfers the resin injected from the pinpoint gate 31 to the boundary surface 2 of the top plate 5.
In order to lead to 3, the same number of gates as the number of gates are arranged directly below the pinpoint gate 31. In addition, a part of the mold for forming the frame of the relay portion 32 is
(Also serving as a part of the liquid chamber 8 forming surface), and the mold of the frame portion of the relay portion 32 formed by the fixed side mold plate 36 can secure sufficient strength.

As described above, since the pinpoint gate 31 and the nozzle row 7 and the orifice plate peripheral portion 6e of the thin portion of the orifice plate are connected in a straight and shortest path, the molding injected from the pinpoint gate 31 is performed. The resin flows smoothly and with small pressure loss to the nozzle row 7 and the orifice plate thin portion (6e) region just below the gate. Further, in the pressure holding step in the molding, the pressure is efficiently applied to the nozzle row 7 and the orifice plate thin-walled portion (6e), so that the filling of the nozzle row 7 and the orifice plate 6 is very good. Becomes

Therefore, the mold structure in which the pinpoint gates for primary molding are arranged near the nozzle row 7 and the thin or thick portion of the orifice plate as in this embodiment, and the top plate structure formed by two-color molding By adopting the above, the top plate molding that could not be obtained with the mold structure or the top plate configuration that injection molding the whole top plate in one step from the fan gate provided on the back of the top plate as in the past It can be realized.

More specifically, even when the top plate is formed with a discharge port having a density of 600 dpi or more, transfer to a finely shaped portion such as the nozzle row 7 can be realized, and the nozzle arrangement length can be increased. Even if it is a long top plate having a length of 100 mm or more, it is possible to fill a wide range of thin and thick portions by increasing the number of pinpoint gates for primary molding to an optimum number and installing them. Further, a long top plate having an ultra-thin orifice plate having a thickness of 20 μm to 50 μm or a nozzle row portion of the long top plate can be formed by resin molding.

When the filling of the primary molding is completed, the movable mold plate 37 is moved in the direction of the arrow to open the mold. In conjunction with this mold opening operation, the pinpoint gate 31 is cut (see FIG. 6) and removed from the mold.

Thereafter, the primary molded product is moved to a position facing the frame of the fixed mold plate for secondary molding while being held by the frame of the movable mold plate 37, and clamped.

In the secondary molding, as shown in FIG. 8, a resin injected from a screw type cylinder (not shown) is injected into a mold from a primary sprue (not shown) for secondary molding, and the resin is injected into the mold. After passing through a runner (not shown), a secondary sprue 43 for secondary molding, and an intermediate gate 42 for secondary molding, the molding frame of the second base 22 is filled from the side gate 41.

As described above, the secondary molding resin is injected from the side surface 5b of the top plate 5 and flows in the longitudinal direction of the top plate 5. Therefore, the longitudinal direction of the filler fibers contained in the resin for secondary molding is oriented toward the longitudinal direction of the orifice plate 6, and the longitudinal direction of the top plate 5 is enhanced against thermal expansion by the orientation effect of the filler. Will be done.

That is, since the first base 21 and the second base 22 are joined and integrated by two-color molding, if the thermal characteristics of the second base 22 in the longitudinal direction are improved, the nozzle row of the two-color molded top plate In the portions 7 and the discharge ports 6a, the thermal expansion characteristics in the arrangement direction are improved by integrating the top plate.

When the filling of the secondary molding is completed, the mold enters the opening operation, and the secondary gate 42 for secondary molding is cut and removed from the mold. Then, the first substrate 2 is formed by two-color molding.
The top plate 5 to which the first and second bases 22 are joined is a side gate 4
Along with one part, it protrudes from the molding frame of the movable mold plate.
The side gate 41 is cut and removed by the side surface 5b of the top plate 5 in a secondary processing step after molding.

Next, problems in composite molding using different materials will be described.

In the present embodiment, for example, the first substrate 21 is formed by two-color molding using polysulfone and the second substrate 22 using carbon fiber-containing polysulfone, but the relative difference between the curing shrinkage ratios of both materials is very large. Therefore, the two-color molded product is liable to undergo a shape change such as warpage or deformation.

That is, a material having a large curing shrinkage tends to cause a large volume change as compared with a material having a small curing shrinkage, so that the curing shrinkage stress of one member acts on the other member. At the interface, a bending stress and a shear stress acting to bend the entire molded product act. As a result, after the two-color molding, the molded part of the molded part tends to shrink greatly because the part is formed of a material having a large shrinkage, and this part is warped in the shrinking direction.

Therefore, the warpage, deformation, and accuracy of a two-color molded product are determined by the balance between the bending rigidity of a molded member made of a material having a small cure shrinkage and the contraction stress generated from a molded member made of a material having a large cure shrinkage. You can say In other words, if a portion formed of a material having a small curing shrinkage has rigidity enough to withstand the bending stress as described above, the warpage of the two-color molded product can be reduced. .

Since the internal stress generated from the boundary surface of such a two-color molded product greatly affects warpage, deformation, and molding accuracy, it is very important to suppress warpage and deformation in dissimilar material molding. It is an issue.

As specific means, the curing shrinkage stress generated from a member formed of a material having a small curing shrinkage is reduced as much as possible, and the rigidity of a member formed of a material having a large curing shrinkage is increased as much as possible. For example, the entire molded article has a proof stress capable of withstanding stress.

Therefore, as one development of this embodiment, by designing the volume of the portion constituting the first base to be as small as possible, the shear stress acting on the boundary surface during the curing shrinkage and the stress acting on the whole molded article can be reduced. Bending stress can be reduced. On the other hand, the second substrate is formed of a material having high mechanical strength so that rigidity that can withstand the stress caused by curing shrinkage of the first substrate can be secured.

In another embodiment, the first substrate is made of polysulfone and the second substrate is made of polysulfone containing 20% by weight of carbon fiber, and the volume of the second substrate is 4 times the volume of the first substrate. When a top plate having a volume ratio of twice or more was formed by two-color molding, the warpage generated on the lower surface of the liquid flow path wall could be suppressed to the same size as a top plate formed of a single material.

When the first base 21 is formed with the thickness set to 1 mm or less, the shear stress and the bending stress acting on the boundary surface 23 are reduced by the effect of reducing the curing shrinkage stress generated from the first base 21 portion. Significantly decreased, and the molding accuracy of the two-color molded top plate could be remarkably improved.

Naturally, the bending stress caused by the curing shrinkage at the time of molding as described above is generated not only from the transfer portion of the molded product but also from the sprue, the runner, the gate, and the like. Will have an effect. Therefore, in order to reduce the amount of warpage of the two-color molded product, it is necessary to accurately take into account the shape of the molded product and the factors of the entire molding path, such as sprues, runners, and gates, and take measures.

In view of the above, it is preferable that a material having a large curing shrinkage is formed by primary molding, and it is better to adopt a pinpoint gate for the primary molding. Since the pinpoint gate is cut and removed from the primary molding frame immediately after the primary molding, the stress caused by the curing shrinkage of the injection path (gate, sprue, runner) upstream of the gate is directed to the primary molding frame. Therefore, it is possible to prevent the stress generated in the upstream portion of the gate from affecting the two-color molded product.

The above is an example of the top plate applied to the configuration of the first embodiment of the present invention. However, the present invention can be implemented on any top plate regardless of the form or shape of the top plate. The effect can be expected.

For example, the surface layer of the orifice plate is separated from the main body of the orifice plate, and the surface layer of the orifice plate is formed using a material having good water repellency. Is integrated by three-color molding, the water-repellent treatment of the surface layer of the orifice plate, which has been conventionally performed by the secondary processing, can be performed during the molding process, and the manufacturing process of the top plate can be simplified.

As means for increasing the rigidity of the top plate,
The method is not limited to the method of using a material with a large elastic modulus, but there is also a method of increasing the rigidity structurally by devising the top plate shape. Can be raised.

In this embodiment, the orifice plate is divided into two parts. However, it is needless to say that the whole area of the orifice plate may be included in the first base, and the orifice plate may be divided into three parts. It is also possible to adopt a configuration formed as described above.

The portion constituting the first base is not limited to the orifice plate and the nozzle row. The liquid chamber is divided into two parts in the vertical direction, and the lower surface of the liquid chamber is added to the first base. The configuration may be such that all portions that come into contact with the liquid are included in the first base. Further, the orifice plate and the nozzle row may be divided so as to form a multicolor molding.

Next, the second embodiment of the liquid discharge head according to the present invention will be described.
An embodiment will be described with reference to FIG. FIG. 9 is a schematic perspective view showing a first base and a second base in a separated manner for explaining an example of the two-color molded top plate of the present embodiment.

In the first embodiment described above, the second base member 22 is formed of a material having a small linear expansion coefficient so as to compensate for the weak point of the thermal expansion in the nozzle row 7. However, in the case of such a structure, If the bonding force between the first base 21 and the second base 22 is small, the restraining force of the second base 22 when the nozzle row 7 tries to expand and contract in the arrangement direction is weakened, and the second base 22 is It becomes difficult to compensate for the weak point of the thermal expansion of the part.
Therefore, in this embodiment, in the two-color molding, the first substrate 2
Even if the molding resin of the first substrate and the molding resin of the second base 22 are difficult to fuse with each other, the weak point of the nozzle row 7 can be overcome.

Hereinafter, a second embodiment of the present invention will be described by assigning the same reference numerals to the same portions as those of the above-described embodiment.

In FIG. 9, reference numeral 51 denotes a row of rib-shaped irregularities provided on the boundary surface 23 of the first base 21, and reference numeral 52 denotes a row of rib-shaped irregularities provided on the boundary 23 of the second base 22. . These uneven rows 51 and 52 are arranged in the same direction as the arrangement direction of the nozzle rows 7 of the first base 21, and the projections 51 a of the first base 21 enter the recesses 52 b of the second base 22, and the second base 22 The concave / convex rows 51 and 52 are alternately arranged so as to face each other such that the convex portion 52a of the first base 21 enters the concave portion 51b of the first base 21. The uneven rows 51 and 52 are arranged so as to avoid the arrangement positions of the gate 31 and the relay section 32 of the first base 21.

As described above, since the two convex portions 51a and 52a alternately enter the opposing concave portions 51b and 52b, the joint area of the boundary surface between the first base 21 and the second base 22 becomes large. The bonding strength between the two increases.

Therefore, if the second base member 22 is formed of a material having a small coefficient of linear expansion, even if the nozzle row 7 of the first base member 21 attempts to expand and contract in the arrangement direction due to a change in environmental temperature, it is provided on both sides. Due to the physical regulation of the uneven rows 51 and 52, the expansion and contraction of the nozzle row 7 is prevented, and the force for restraining the expansion and contraction of the nozzle row 7 is increased as compared with a top plate having no uneven rows.

[0132] Further, if the irregularities are formed in a shape in which both are undercut in the peeling direction, the bonding strength between the two substrates is significantly improved by adding physical reinforcement to the fusion strength of the opposing materials. become.

Further, when the uneven lines 51 and 52 at the boundary are formed in an undercut shape, the material of the first base 21 and the material of the second base 22 are unlikely to be fused at the time of two-color molding, and the bonding strength between the two is reduced. Even if the top plate is reduced in size, the uneven rows 51 and 52 can physically restrict expansion and contraction stress in the arrangement direction of the nozzle rows 7 due to thermal expansion and press down. Therefore, if such a configuration is adopted, a combination of molding materials for the first base 21 and the second base 22 can be selected regardless of whether or not the fusibility of both materials is good.

On the other hand, if a material that easily fuses the first base 21 and the second base 22 is selected, the bonding area between them becomes large, and the bonding force between them becomes strong in two directions, the peeling direction and the nozzle arrangement direction. Become. Furthermore, if the thermal expansion characteristics of the second base 22 are good, the force for restraining the expansion and contraction of the nozzle row 7 in the arrangement direction in the two-color molded top plate is significantly improved.

In addition, the uneven rows may be arranged at equal intervals or irregularly. However, if arranged at equal intervals, the molding resin flows stably and regularly,
In addition to improving the filling property, it also contributes to the effect of suppressing the warpage of the molded product, so that the molding accuracy can be improved.

As the means for restraining the nozzle row 7 in the second embodiment described above, the rib-shaped uneven rows 51 and 52 are provided on the boundary surface between the first base 21 and the second base 22. The constraining means is not limited to the rib-shaped concavo-convex array, and the same effect can be obtained even with a concavo-convex array such as a bellows, a boss, a seat, and a rectangle.

The uneven rows are not limited to being arranged in the direction in which the nozzle rows 7 are arranged, but may be arranged in the liquid ejection direction.

The nozzle row restricting means is not limited to the concavo-convex row, but may have a structure in which the second base 22 holds both side faces of the nozzle row 7. Also,
A greater effect can be expected by using both the arrangement of the uneven rows and the holding of both side surfaces.

In this embodiment, the weak point of the thermal expansion in the nozzle row 7 has been described. However, the configuration of the second embodiment is as follows.
The second base 22 is also an effective means for improving the rigidity of the entire top plate.

[0140]

As described above, according to the present invention,
The top plate member does not include the first base including the lower half of the orifice plate including the periphery of the discharge port and the liquid flow path groove, with the vicinity of the upper portion of the liquid flow path groove and the discharge port as a boundary surface, and does not include the discharge port. The upper half of the orifice plate is divided into a second base comprising a liquid chamber and a liquid supply port, and the first base and the second base are formed by primary forming the first base and the second base by secondary forming, respectively. By adopting a configuration in which the two substrates are joined and integrated by two-color molding, the first substrate has a simple shape, the flow and orientation of the injected resin are stable, and no extra pressure loss occurs during the flow. The molding accuracy and filling property of the nozzle, the planar accuracy of the lower surface of the nozzle row, etc. can be improved. Also, by combining various resins, ceramics, metals, fillers, etc., two-color molding (or multi-color molding) is possible. In the molding of one material Allowing the molding of multi-functional top plate with high precision not present.

Further, since the orifice plate is formed by being divided into two steps of the lower half and the upper half including the peripheral part of the discharge port, the area where the thin and thick part is dominant in one molding step becomes small. As compared with the case where the entire orifice plate is molded at one time, the filling of the thin and thick portion becomes easier, and the moldability can be remarkably improved.

Further, by providing a primary molding gate for molding the first base on the boundary surface near the upper portion of the liquid flow channel with a pinpoint gate, the gate, the liquid flow channel, and the orifice plate thin-walled portion can be formed. The connection is made in a straight line and the shortest path, and the molding resin injected from the gate flows smoothly to the liquid flow path and the orifice plate thin-walled portion. Since it acts directly on the orifice plate thin part, the holding pressure in the pressure holding step is efficiently applied toward the liquid flow path wall and the orifice plate thin part. The filling property to the thin portion and the orifice plate thin portion becomes very good. In addition, by providing a relay portion connecting the primary molding gate and the boundary surface near the upper part of the liquid flow channel, the primary molding gate can be installed without excessively increasing the volume of the first base. For,
A high-precision two-color molded top plate can be manufactured, and further, a decrease in the mold strength around the gate can be prevented, and the productivity is improved.

By optimally setting the position and quantity of the pinpoint gates for the primary molding of the first base, the discharge ports which have been difficult in injection molding of a single resin can be increased to 600 dpi or more. Densified top plate and 20μm ~
Even a long top plate having an ultra-thin orifice plate of 50 μm and having a liquid flow path arrangement length of 100 mm or more, regardless of the length of the top plate, the thin portion of the orifice plate The fine portion of the liquid channel wall can be filled well.

Further, since the pinpoint gate is cut and removed from the molding frame immediately after the primary molding, the stress generated by the curing shrinkage of the gate, sprue, and runner acts on the primary molding frame. This makes it possible to prevent the stress generated upstream of the gate from affecting the two-color molded product.

[0145] By forming the top plate in a composite molding of different materials, the molding resin of the second base can be molded using various materials, and the two can be integrally joined by two-color molding. Thereby, improvement can be achieved in terms of rigidity such as elastic modulus and performance in terms of thermal expansion and the like.

By arranging the secondary molding gate on the side surface in the longitudinal direction of the top plate, when the second base is molded from a resin containing a fibrous filler or a material having a large anisotropy, the filler may be used. The contained resin flows in the liquid flow path arrangement direction of the top plate, and the filler fibers and the like are oriented in the liquid flow path arrangement direction, so that the resin orientation control can be efficiently performed,
Thermal expansion, elastic modulus, molding cure shrinkage, and other mechanical strengths are maximized in the liquid flow direction. As a result, the second substrate has the rigidity and thermal expansion characteristics of the secondary molding material, and the top plate molded by two-color molding has a rigidity that cannot be obtained by molding with a single material. At the same time, the thermal expansion characteristics in the liquid flow direction are significantly improved.

By molding the second base with a material having a smaller linear expansion coefficient than the material injected into the first base, the two-color molded top plate in which the two bases are integrated is formed by the heat of the second base. The expansion characteristic is imparted, so that thermal expansion and contraction around the liquid flow passage array and around the discharge port under environmental fluctuations can be suppressed. In addition, since this can be effectively developed even for a top plate having a high-density liquid channel row or a long top plate, various types of top plates can be formed, and the molded top plate can be formed. Can be remarkably improved.

Further, by setting the volume of the second substrate to be at least four times the volume of the first substrate, the volume occupied by the second substrate portion in the two-color molding top plate becomes large. Although the shear stress and the bending stress generated by the molding / hardening shrinkage of the first base portion act on the boundary surface of the base, the second base portion has rigidity enough to withstand these internal stresses. The molded top plate is not affected by quality, such as warpage, deformation, and accuracy. Further, by setting the thickness of the first base to 1 mm or less,
The curing shrinkage stress generated from the first base part is remarkably reduced, and the shear stress and bending stress acting on the interface between the two bases are also reduced. Can be done.

Further, by forming the first base body with a transparent member, the filling condition of the sealant can be confirmed from the front surface of the orifice plate, and the productivity in the assembling and inspection steps is improved. In addition, by forming the first substrate with polysulfone, a transparent orifice plate can be formed, excellent in laser workability and ink resistance for forming the discharge port, and has good fluidity and easy precision molding. In processing the orifice plate, necessary conditions can be ensured. Also,
By making the base resin of the material injected into the second base the same as the base resin of the material injected into the first base, the bonding property between the first base and the second base in multicolor molding is improved. The completed top plate can be completely integrated as in the case of one-color molding, and can be molded with higher precision than in the case of one-color molding.

Further, by forming ribs, bellows, bosses, seats, or rectangular irregularities on the boundary surface between the first base and the second base, the bonding area between the first base and the second base can be increased. And the bonding between them can be further strengthened. Furthermore, in the case where a resin having a small coefficient of thermal expansion is used for the second base, even if the top plate is placed in an environment with a large temperature change and the first base attempts to change the volume,
This is physically prevented by the rigidity of the second base and the irregularities on the boundary surface, so that the volume change of the first base can be more effectively suppressed. In addition, if the uneven shape of the boundary portion is formed so that both are undercut in the peeling direction, even if the first base and the second base are formed of different materials, or the bonding strength is small, Both can be integrated, and the material properties of the second base can compensate for the weakness of the material properties of the first base. Furthermore, the combination of the molding materials of the first substrate and the second substrate can be selected regardless of the fusibility of the two materials.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an example of the configuration of a first embodiment of a liquid ejection head according to the present invention.

FIG. 2 is a schematic perspective view showing an exploded example of the configuration of the first embodiment of the liquid ejection head according to the present invention.

FIG. 3 is a schematic perspective view showing an example of a top plate formed by two-color molding in the first embodiment of the liquid ejection head according to the present invention.

FIG. 4 is a schematic sectional view showing an example of a top plate formed by two-color molding in the first embodiment of the liquid ejection head according to the present invention.

FIG. 5 is a schematic perspective view showing an aspect of primary molding of a top plate in the first embodiment of the liquid ejection head according to the present invention.

FIG. 6 is a schematic perspective view showing a state after the gate is cut after the primary molding of the top plate in the first embodiment of the liquid discharge head according to the present invention.

FIG. 7 is a schematic cross-sectional view showing a configuration of a mold for primary molding of a top plate in the first embodiment of the liquid discharge head according to the present invention.

FIG. 8 is a schematic perspective view showing an aspect of the secondary molding of the top plate in the first embodiment of the liquid ejection head according to the present invention.

FIG. 9 is a schematic perspective view showing a first base and a second base separated from each other to explain the configuration of a two-color molding top plate in a second embodiment of the liquid ejection head according to the present invention.

FIG. 10 is a schematic perspective view showing a molding mode of a top plate in a conventional liquid ejection head.

FIG. 11 is an exploded perspective view showing a schematic configuration of a conventional liquid ejection head.

[Explanation of symbols]

 Reference Signs List 1 element substrate 1a discharge energy generating element (heat generating element) 2 wiring board 3 support substrate 5 top plate (member) 6 orifice plate 6a discharge port 6c orifice plate lower half 6d orifice plate upper half 6e discharge port peripheral part 7 nozzle ( Row) 7a Groove wall lower surface 8 Liquid chamber 8a Liquid chamber upper surface 8c Liquid chamber lower surface 9 Liquid supply port 10 Holding spring 21 First substrate 22 Second substrate 23 Boundary surface 31 Primary molding gate (pin point gate) 32 Relay portion 33 Primary Secondary sprue for molding 34 Runner for primary molding 36 Fixed mold plate 37 Movable mold plate 38 Movable slide mold piece 41 Secondary molding side gate 42 Secondary molding intermediate gate 43 Secondary molding secondary sprue 51, 52 row of irregularities

Claims (13)

[Claims] An element substrate provided with a discharge energy generating element for applying discharge energy to the liquid corresponding to the plurality of liquid flow paths; a liquid flow path groove corresponding to the plurality of liquid flow paths; An orifice plate provided with an array of discharge ports for discharging liquid in communication with one end of the passage groove, and a liquid chamber for supplying liquid to the liquid passage groove by communicating with the other end of the liquid passage groove; A liquid supply port for supplying a liquid to the liquid chamber, and a top plate member integrally formed with a liquid flow channel, an orifice plate, a liquid chamber, and a liquid supply port, and by joining the element substrate to the top plate member. In the liquid discharge head that forms the liquid flow path, the top plate member has a lower surface of the orifice plate including the discharge port as a boundary surface near the liquid flow path groove and the discharge port and the liquid flow path. A first base composed of a groove, and the discharge port The first base and the second base are divided into a first base and a second base formed by forming a first base by forming a second base composed of the upper half of the orifice plate not containing the liquid chamber and the liquid supply port. A liquid ejection head, which is integrally joined by two-color molding in which a base is molded by secondary molding. 2. The liquid discharge head according to claim 1, wherein a gate for primary forming the first base is provided on the boundary surface above the liquid flow channel. 3. The liquid discharge head according to claim 2, wherein a gate for primary molding of the first base is a pinpoint gate at one or a plurality of positions. 4. The liquid discharge head according to claim 2, further comprising a relay portion connecting between the gate for primary molding of the first base and the boundary surface for connecting the two. . 5. A gate for secondary molding the second base is disposed on a longitudinal side surface of the top plate member, and the secondary molding resin flows in a liquid flow direction arrangement direction of the top plate member. The liquid discharge head according to claim 1, wherein the liquid discharge head is configured as described above. 6. The method according to claim 1, wherein the second substrate is formed of a material having a smaller coefficient of linear expansion than a material injected into the first substrate. Liquid ejection head. 7. The liquid discharge head according to claim 1, wherein the volume of the second base is at least four times the volume of the first base. 8. The liquid discharge head according to claim 1, wherein the thickness of the first base is 1 mm or less. 9. The liquid discharge head according to claim 1, wherein the first base is formed of a transparent member. 10. The liquid discharge head according to claim 1, wherein the first base is formed of polysulfone. 11. The liquid discharge head according to claim 1, wherein the second base is formed of a composite material filled with fillers such as fibers and beads. 12. The method according to claim 1, wherein the base resin of the material injected into the second base is the same as the base resin of the material injected into the first base. Item 6. The liquid ejection head according to item 1. 13. A rib, a bellows, a boss, a seat, or a rectangular uneven row is formed on a part of a boundary surface between each of the first base and the second base. 13. The method according to claim 1, wherein the concave portion of the second substrate enters the concave portion of the second substrate, and the convex portion of the second substrate enters the concave portion of the first substrate. 14. Liquid ejection head.