JP2001038907A - Liquid emitting head, liquid emitting method, liquid emitting device and production of liquid emitting head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve the enhancement of refill characteristics and the stabilization of emitting quantity after a substantially hermetically closed space is formed by a movable member and a regulation part. SOLUTION: The liquid flow channel 10 communicating with an emitting orifice 18 is constituted by bonding an element substrate 1 equipped with a heating element 2 and a top plate 50. A cantilevered movable member 31 is arranged to the element substrate 1 in opposed relation to the heating element 2 and a stopper 64 is provided to the top plate 50 in opposed relation to the heating element 2 and the leading end part of the movable member 31 comes into contact with the stopper 64 to divide the liquid flow channel 10 into a downstream part including the heating element and an upstream part not including the same. The movable member 31 is elastically bent toward the upstream part in a protruded state before the air bubble 40 generated by the driving of the heating element grows maximally and subsequently separated from the stopper 64 in a contraction stage of the air bubble 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid ejection head for ejecting a desired liquid by generating bubbles generated by applying thermal energy to the liquid, a head cartridge using the liquid ejection head, and a liquid ejection apparatus. In particular, the present invention relates to a liquid ejection head having a movable member that is displaced by utilizing the generation of bubbles, a head cartridge using the liquid ejection head, and a liquid ejection apparatus.

[0002] The present invention also relates to a facsimile having a printer, a copier, a communication system, and a printer for performing recording on a recording medium such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics and the like. The present invention can be applied to a device such as a word processor having a unit, and further to an industrial recording device combined with various processing devices.

In the present invention, "recording" means not only giving an image having a meaning such as a character or a figure to a recording medium, but also giving an image having no meaning such as a pattern. Also means

[0004]

2. Description of the Related Art By giving energy such as heat to ink, a state change accompanied by a steep volume change (formation of bubbles) is caused in the ink, and the ink is ejected from an ejection port by an action force based on this state change. An ink jet recording method in which an image is formed by attaching the ink onto a recording medium, that is, a so-called bubble jet recording method, is conventionally known. As disclosed in U.S. Pat. No. 4,723,129 and the like, a recording apparatus using the bubble jet recording method includes a discharge port for discharging ink, and an ink flow communicating with the discharge port. A passage and an electrothermal converter as an energy generating means for discharging ink arranged in the ink flow path are generally arranged.

According to such a recording method, a high-quality image can be recorded at high speed and with low noise, and in a head performing this recording method, ejection ports for ejecting ink are arranged at a high density. Therefore, it has many advantages that a high-resolution recorded image and a color image can be easily obtained with a small device. For this reason, this bubble jet recording method has recently been used in many office devices such as printers, copiers, and facsimile machines, and has also been used in industrial systems such as textile printing devices.

[0006] As the bubble jet technology is used for products in various fields, the following various requirements have been increasing in recent years.

In order to obtain a high-quality image, a driving condition for providing a liquid discharging method or the like in which the ink discharging speed is high and a good ink discharging based on stable bubble generation is proposed. In view of the above, there has been proposed an improved liquid flow path in order to obtain a liquid discharge head having a high filling (refilling) speed of the discharged liquid into the liquid flow path.

In addition to such a head, attention is paid to a back wave (pressure in a direction opposite to a direction toward a discharge port) generated due to the generation of bubbles, and a back wave which becomes energy loss in discharge is focused on. The invention of the structure to prevent this is disclosed in
No. 31,918 (in particular, FIG. 3). In the invention described in this publication, a triangular portion of a triangular plate member is opposed to a heater that generates bubbles. In the present invention, the back wave is temporarily and slightly suppressed by the plate member. However, there is no mention of the correlation between bubble growth and the triangular portion, and there is no idea, so the above-described invention has the following problems.

That is, in the invention described in the above publication, since the heater is located at the bottom of the concave portion and cannot be in linear communication with the discharge port, the droplet shape cannot be stabilized, and the growth of bubbles is triangular. Air bubbles grow from one side of the triangular plate to the whole of the other side, and consequently the normal bubble in the liquid as if the plate was absent. The growth of bubbles is completed. Therefore, the existence of the plate-shaped member has nothing to do with the grown bubble. Conversely, since the entire plate-shaped member is surrounded by bubbles, during the bubble contraction stage, refilling the heater located in the concave portion causes turbulence, causing microbubbles to accumulate in the concave portion and grow. This disturbs the principle of discharging based on bubbles.

On the other hand, European Patent Application Publication No. 4360
Japanese Patent No. 47 gazette alternately includes a first valve that shuts off between the vicinity of the discharge port and the bubble generator, and a second valve that completely shuts them off between the bubble generator and the ink supply unit. The invention which opens and closes is proposed (the 4th publication of JP-B-436047).
To 9). However, according to the present invention, since these three rooms are divided into two chambers, the ink following the droplets at the time of ejection has a large tail, which is compared with a normal ejection method in which bubble growth, contraction, and defoaming are performed. Therefore, the number of satellite dots becomes considerably large (it is estimated that the effect of meniscus retreat due to defoaming cannot be used). Also, at the time of refilling, the liquid is supplied to the bubble generating section with the defoaming, but the liquid cannot be supplied to the area near the discharge port until the next foaming occurs,
Not only is the dispersion of the ejected droplets large, but the ejection response frequency is extremely low, which is not practical.

[0011]

The invention using a movable member (a plate-like member having a free end closer to the ejection port than the fulcrum) which can contribute effectively to the ejection of the droplet is completely different from the above-mentioned prior art. Many have been proposed. Of that invention,
Japanese Patent Laying-Open No. 9-48127 discloses an invention in which the upper limit of the displacement of the movable member is regulated in order to prevent the behavior of the movable member from being slightly disturbed. Japanese Patent Application Laid-Open No. 9-323420 discloses that the position of the common liquid chamber upstream of the movable member is shifted to the free end side of the movable member, that is, the downstream side by utilizing the advantage of the movable member. It discloses an invention that enhances the refill capability. These were based on the assumption that the invention would be created, because the bubble growth was temporarily wrapped by a movable member and opened at a stroke to the discharge port side. And
No attention has been paid to their correlation.

Also, European Patent Application Publication No. 0436
Japanese Patent No. 047 describes that two valve members that are initially shut off are provided upstream / downstream of the bubble generation region to increase the ejection cycle and the droplet ejection efficiency. Valves cause a significant loss of discharge energy. Also, 2
There is a valve in the stage that is in the shut-off state, which causes a large resistance to the refill liquid flow.Especially, if the meniscus retreats from the position of the discharge port for some reason, it becomes almost impossible to refill, and it is practical in terms of performance. Not.

As the next step, the applicant of the present invention has
In -24588, an invention (acoustic wave) focused on bubble growth due to pressure wave propagation as an element related to liquid ejection,
The invention discloses that a part of the bubble generation region is released from the movable member. However, also in the present invention, since attention is paid only to the growth of bubbles during liquid ejection, attention is not paid to individual elements related to the formation of droplets themselves and their correlations.

It is known that the front part (in the case of the edge shooter type) of the bubble caused by film boiling, which is conventionally known, has a great influence on the discharge, but this part is used to form the discharged droplets more efficiently. There has been no prior focus on contributing, and the present inventors have conducted intensive research to elucidate these technical aspects.

The present invention is one of a number of inventions that have been made by analyzing the process from generation of bubbles to defoaming in more detail from the viewpoint of the formation of discharged droplets.
Regarding the improvement of the refill characteristics and the stability of the discharge amount after forming a substantially closed space by the movable member and the restricting portion, the preferable characteristics required for the movable member from the growth of the front part of the bubble to the start of defoaming It was made after examination.

A first object of the present invention is to pay attention to a substantial liquid stagnant state on the upstream side with respect to a change on the discharge port side of a substantially closed space at the time of discharging a droplet, and to examine a variation in a foaming state. The purpose is to suppress the variation in the discharge amount due to this.

A second object of the present invention is to improve the refill characteristics of the ink jet head and to ensure the stability by changing the inertial force of the fluid in the stationary state to a state that can contribute to refilling in advance. .

A third object of the present invention is to form the above substantially closed space at a higher speed after the movable member is displaced during refill.

[0019]

In order to achieve the above object, a liquid discharge head according to the present invention comprises a heating element for generating heat energy for generating bubbles in a liquid, and a discharge port for discharging the liquid. A liquid flow path having a bubble generation region in which the bubbles are generated and communicating with the discharge port, a cantilevered movable member displaceably provided in the bubble generation region, and facing the bubble generation region. A liquid ejecting head for ejecting the liquid from the ejection port with energy at the time of the generation of the bubble, the movable member being provided with a regulating portion that regulates a displacement range of the movable member. In an initial state in which the bubbles are not generated, the liquid flow path is substantially divided into a downstream side including the bubble generation region and an upstream side not including the bubble generation region by contacting the regulating portion, and before the bubbles grow to the maximum. The liquid flow path is substantially Resiliently convexly curved toward the upstream side in the divided state, characterized by opening the contact between the restricting portion is displaced by the contraction force of the defoaming of the bubble.

According to the liquid discharge head of the first aspect, the movable member divides the liquid flow path into an upstream state and a downstream state in the initial state, and moves toward the upstream side before the bubble grows to the maximum. Since the flexible member is elastically curved in a convex shape, a variation in the foaming state due to a variation in the heat generation characteristics of the heating element is formed by the bending of the movable member. As a result, variations in the liquid discharge amount due to variations in the foaming state are suppressed. In the bubble contraction stage, the movable member is displaced by the contraction force of the bubble defoaming to release the contact with the restricting portion, whereby the liquid is refilled into the liquid flow path. In the above-described liquid ejection head, the convexly curved portion of the movable member may be concavely curved by the elastic force of the movable member itself at the time of bubble contraction. Thus, the liquid can be initially moved in the refill direction before the main refill is started, so that the refill is executed stably and quickly.

Further, the liquid discharge head of the present invention has a heating element for generating thermal energy for generating bubbles in the liquid, a discharge port from which the liquid is discharged, and a bubble generation region in which the bubbles are generated. A liquid flow path communicating with the discharge port, a cantilevered movable member provided displaceably in the bubble generation region, and a displacement range of the movable member provided opposed to the bubble generation region to regulate the displacement range of the movable member; A liquid ejecting head for ejecting the liquid from the ejection port with energy at the time of the generation of the bubble, wherein the movable member has an initial state in which the bubble is not generated. The liquid flow path is substantially divided into a downstream side including the bubble generation region and an upstream side not including the bubble generation region by being in contact with the restriction portion by an elastic force, and is displaced by a contraction force of the defoaming of the bubble to restrict the liquid flow. Contact with the department Characterized by release.

According to the liquid discharge head of the second aspect, the movable member contacts the regulating portion for dividing the liquid flow path into the upstream and the downstream by the elastic force of the movable member. The division of the liquid flow path until the liquid is refilled into the liquid flow path is reliably performed. In addition, since the displacement of the movable member at the time of refilling the liquid into the liquid flow path is performed by further elastically deforming the movable member, a larger internal stress is generated in the movable member when the movable member is displaced. The movable member can be returned at a higher speed.

Further, in the first and second liquid discharge heads described above, the movable member may have a structure having a convex portion protruding to the side opposite to the regulating portion at a portion close to the bubble generation region. it can. With such a configuration, the growth of bubbles in the upstream direction is suppressed by the convex portion, and accordingly, the movement of the liquid in the upstream direction is reduced. As a result, the refill of the liquid is improved.

[0024] The liquid discharging method of the present invention comprises: a heating element for generating thermal energy for generating bubbles in the liquid;
A discharge port from which the liquid is discharged, a liquid flow path having a bubble generation region in which the bubbles are generated, and communicating with the discharge port, a cantilevered movable member displaceably provided in the bubble generation region, A liquid discharge head comprising a liquid discharge head for discharging the liquid from the discharge port with energy at the time of generation of the bubbles, the liquid discharge head comprising a restricting portion provided to face the bubble generation region and restricting a displacement range of the movable member. In the discharge method, in an initial state in which the bubbles are not generated, the movable member is substantially in contact with the restricting portion to move the liquid flow path to a downstream side including the bubble generation region and an upstream side not including the bubble generation region. And after the bubble is generated, before the bubble grows to the maximum, the movable member is elastically convexly curved toward the upstream side in a state where the liquid flow path is substantially separated. And in the step of shrinking the bubbles, It said movable member is displaced by the contraction force of the defoaming serial bubbles, characterized in that a step of releasing the contact with the restricting portion.

According to the above method, the movable member is elastically convexly curved before the bubble grows to the maximum in a state where the movable member substantially divides the liquid flow path into the upstream and the downstream. Since the method includes the step, the variation in the liquid ejection amount due to the variation in the foaming state is suppressed. Furthermore, by having a process in which the convexly curved portion of the movable member is concavely curved by its elastic force before the movable member is displaced in the bubble contraction stage,
Before the start of the main refill, the liquid can be moved in the refill direction, and the refill can be performed stably and quickly.

Further, the liquid discharging method of the present invention includes a heating element for generating thermal energy for generating bubbles in the liquid, a discharge port from which the liquid is discharged, and a bubble generating region where the bubbles are generated. A liquid flow path communicating with the discharge port,
A cantilevered movable member provided displaceably in the bubble generation region, and a regulating portion provided opposite to the bubble generation region to regulate a displacement range of the movable member, when the bubble is generated A liquid ejection method using a liquid ejection head that ejects the liquid from the ejection port with energy, wherein in an initial state in which the bubble is not generated, the movable member is moved to the regulating portion by the elastic force of the movable member. Contacting and substantially dividing the liquid flow path into a downstream side including the bubble generation region and an upstream side not including the bubble generation region; and And the step of displacing to release the contact with the restricting portion.

According to the above method, in the initial state in which no bubbles are generated, the movable member comes into contact with the regulating portion by elastic force to substantially divide the liquid flow path into upstream and downstream.
Since the movable member is displaced in the bubble contraction stage to release the contact with the restricting portion, the return from the displaced state of the movable member to the contact portion with the restricting portion is performed at high speed.

A liquid ejecting apparatus according to the present invention includes the above-described liquid discharge head according to the present invention, and recording medium transport means for transporting a recording medium which receives the liquid discharged from the liquid discharge head. . Further, the recording may be performed by discharging ink from the liquid discharge head and attaching the ink to a recording medium.

Further, the present invention provides a method for manufacturing the above-mentioned liquid discharge head. The method of manufacturing a liquid discharge head according to the present invention includes a heating element that generates thermal energy for generating bubbles in the liquid, a discharge port from which the liquid is discharged, and a bubble generation region in which the bubbles are generated. A liquid flow path communicating with the discharge port, a cantilevered movable member movably provided in the bubble generation region, and a regulation provided opposite to the bubble generation region to regulate a displacement range of the movable member. A method for manufacturing a liquid discharge head that discharges the liquid from the discharge port by using energy at the time of generation of the bubble, wherein a step of preparing a top plate member including the discharge port and the regulating unit is provided. Preparing a substrate member including the heating element and the movable member, and joining the top plate member and the substrate member to form the liquid flow path, wherein the top plate member And the substrate member The joining step includes a step of substantially dividing the liquid flow path into a downstream side including the bubble generation region and an upstream side not including the bubble generation region by contacting the regulating portion in a state where the movable member is elastically deformed. It is characterized by.

As described above, in the joining step between the top plate member and the substrate member, the movable member is elastically deformed and brought into contact with the regulating portion, thereby dividing the liquid flow path into the downstream side and the upstream side. A liquid discharge head is manufactured in which the liquid flow path is surely divided until the liquid refilling of the liquid flow path is started, and the operation from the displaced state of the movable member to the return can be performed at a high speed.

The other effects of the present invention can be understood from the description of each embodiment.

The terms “upstream” and “downstream” used in the description of the present invention refer to the flow direction of a liquid from a liquid supply source to a discharge port through a bubble generation region (or a movable member).
Alternatively, it is expressed as an expression regarding this structural direction.

The "downstream side" of the bubble itself is as follows.
With respect to the center of the bubble, it means a bubble that is generated on the downstream side in the flow direction or the configuration direction, or on the downstream side of the area center of the heating element. Similarly, "upstream" with respect to the bubble itself refers to a bubble generated in an area upstream of the center of the bubble with respect to the flow direction or the direction of the structure, or in an area upstream of the area center of the heating element. I do.

The “substantial contact” between the movable member and the restricting portion used in the present invention is a state in which the movable member and the regulating portion are in direct contact with each other even if a liquid of about several μm is interposed therebetween. Is also good.

[0035]

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

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 7 is a cross-sectional view of the liquid discharge head according to the embodiment cut along the liquid flow path direction, and shows characteristic phenomena in the liquid flow path in steps (a) to (g). is there.

In the liquid ejection head of this embodiment, a heating element 2 for applying thermal energy to the liquid is provided on a smooth element substrate 1 as an ejection energy generating element for ejecting the liquid. A liquid flow path 10 is arranged corresponding to the heating element 2. The liquid flow path 10 communicates with the discharge port 18 and also communicates with a common liquid chamber 13 for supplying liquid to the plurality of liquid flow paths 10, and has an amount corresponding to the liquid discharged from the discharge port 18. Liquid is received from this common liquid chamber 13. The symbol M represents a meniscus formed by the discharged liquid,
The meniscus M is balanced in the vicinity of the discharge port 18 with the internal pressure of the common liquid chamber 13 which is usually a negative pressure by the capillary force generated by the discharge port 18 and the inner wall of the liquid flow path 10 communicating therewith.

The liquid flow path 10 is formed by joining the element substrate 1 provided with the heating element 2 and the top plate 50, and the area near the surface where the heating element 2 and the discharge liquid are in contact is formed. There is a bubble generation region 11 where the body 2 is rapidly heated to cause foaming of the discharged liquid. At least a part of the movable member 31 is arranged in the liquid flow path 10 having the bubble generation region 11 so as to face the heating element 2. The movable member 31 has a free end 32 on the downstream side toward the discharge port 18 and is supported by a support member 34 arranged on the upstream side. In particular, in the present embodiment, the free end 32 is disposed near the center of the bubble generation region 11 to suppress the growth of the upstream half of the bubble, which affects the back wave to the upstream side and the inertial force of the liquid. The movable member 31 can be displaced with respect to the support member 34 as bubbles generated in the bubble generation region 11 grow. The fulcrum 33 at the time of this displacement serves as a support portion of the support member 34 for the movable member 31.

Above the center of the bubble generation area 11, the top plate 5
A stopper (restriction part) 64 provided integrally with the cylinder 0 is located. In the initial state (before the generation of bubbles), the movable member 31 for suppressing the growth of approximately half of the upstream side of the bubbles has its tip substantially in contact with the stopper 64 due to its elastic force. The downstream side of the flow path 10 is substantially blocked from the upstream side. In the flow from the common liquid chamber 13 to the discharge port 18, a low flow resistance region 65 having a lower flow resistance than the liquid flow path 10 is provided on the upstream side of the stopper 64. The flow path structure in this area 65 has no upper wall or has a large flow path cross-sectional area, so that the resistance to the movement of the liquid from the flow path is reduced.

As described above, in the present embodiment, the portion having the bubble generation region 11 of the liquid flow path 10 becomes a substantially closed space except for the discharge port 18 due to the contact between the movable member 31 and the stopper 64. That is a unique head structure that has never existed before.

Next, the discharge operation of the liquid discharge head of the present embodiment will be described in detail.

FIG. 1A shows a state before energy such as electric energy is applied to the heating element 2, that is, a state before the heating element generates heat. The important thing here is that
The movable member 31 is provided at a position facing almost half of the upstream side of the bubble generated by the heat generated by the heating element 2, and the movable member 31 and the stopper 64 are located above the center of the bubble generation region 11. Before the bubble generation, the liquid flow path structure, the position of the movable member 31, and the elastic force of the movable member 31 cause the movable member 31 to come into contact with the stopper 64, thereby causing the bubble in the liquid flow path 10. Generation area 11
Is shut off from the upstream side.

FIG. 1B shows a state in which a part of the liquid filling the bubble generation region 11 is heated by the heating element 2, and the bubbles 40 accompanying film boiling have grown almost to the maximum. At this time, the pressure wave based on the generation of the bubble 40 propagates in the liquid flow path 10, and accordingly, the liquid moves downstream and upstream with the center region of the bubble generation region 11 as a boundary. As a result, the movable member 31 is curved convexly toward the upstream side due to the flow of the liquid accompanying the growth of the bubbles 40 on the upstream side, and the discharge droplets 66 are being discharged from the discharge port 18 on the downstream side. The amount of bending of the movable member 31 is a very small range of about 20 μm at the maximum. In addition, the convex curvature is displaced before the maximum growth of the bubble.

Here, the movement of the liquid in the upstream side, that is, in the direction of the common liquid chamber 13, is blocked by the movable member 31 and the stopper 64, so that the movement of the liquid in the upstream direction is also greatly restricted there. . Accordingly, the growth of the bubble 40 on the upstream side is also restricted by the movable member 31. However, since the moving force of the liquid in the upstream direction is large, the movable member 31 receives a large stress that is pulled in the upstream direction. Further, a part of the bubble 40 whose growth is restricted by the movable member 31 passes through a slight gap between both side walls forming the liquid flow path 10 and a side portion of the movable member 31 and rises to the upper surface side of the movable member 31. are doing. This raised bubble will be referred to herein as a “raised bubble (41)”.

In this state, the overall shape of the liquid flow path 10 toward the discharge port 18 with respect to the movable member 31 has a structure that expands from the upstream side to the downstream side.

In the present invention, as shown in FIG. 13, the range indicated by the broken line between the portion on the discharge port side of the bubble (the portion downstream of the central region of the heating element 2) and the discharge port 18 is the liquid flow. In contrast, a “linear communication state” is maintained in which a straight flow path structure is maintained. This is more preferably achieved by linearly matching the direction of propagation of the pressure wave generated at the time of the generation of the bubble with the direction of flow of the liquid, and the direction of discharge, so that the discharge state of the discharge droplet 66 and the discharge speed, etc. Is desirable in that an ideal state of stabilizing at an extremely high level can be formed. In the present invention, as one definition for achieving or approximating this ideal state, the discharge port 18 and the heating element 2, particularly, the discharge port side (downstream side) of the heating element having an influence on the discharge port side of the bubble. May be directly connected by a straight line. This is a state in which the heating element, particularly the downstream side of the heating element, can be observed from the outside of the discharge port if there is no fluid in the flow path. It is.

On the other hand, as described above, the upstream portion of the bubble 40 is moved by the movable member 31 and the stopper 64 to the liquid flow path 10.
, The movable member 31 has a small size in a state where the movable member 31 is curved to a convex shape on the upstream side by the inertia force of the liquid flow to the upstream side and charged until the stress is charged. As a whole, the amount of the stopper and the liquid flow path partition wall 101, the movable member 31, and the fulcrum 33 entering the upstream region is almost negligible (however, the movable member 31 and the liquid flow path partition wall are not provided). Partially raised bubbles for a space of 10 μm or less in the gap with 101 are allowed.)

In the case of the present invention, as described above, no displacement other than the convex curvature of the movable member 31 is performed during foaming. For this reason, the movable member 3
Energy for the downward displacement of 1 is important because the restoring force of the movable member 31 is added to the defoaming force of bubbles.

This greatly restricts the liquid flow to the upstream side, and prevents fluid crosstalk to the adjacent nozzles, liquid backflow and pressure oscillation in the supply path system that inhibits high-speed refilling, which will be described later. Fluctuations in ejection volume are suppressed.

FIG. 1C shows a state in which the negative pressure inside the bubble overcomes the movement of the liquid to the downstream side in the liquid flow path 10 after the above-described film boiling, and the contraction of the bubble 40 is started. .
At this time, since the force in the upstream direction of the liquid due to the bubble growth remains largely, the flow path is blocked by the movable member 31 and the stopper 64 for a certain period after the start of the contraction of the bubble 40, and the bubble 40 Most of the contraction causes a liquid moving force in the upstream direction from the discharge port 18. In the state of FIG.
Since the movable member 31 is in a stress-charged state in which the movable member 31 is curved in a convex shape toward the upstream side, in FIG. 1C, the movable member itself draws back the liquid flow from the side that releases the stress caused by the bending, that is, from the upstream side. A force that tends to be concave toward the upstream direction is generated. For this reason, from a certain point in time before the main refilling is started, the retraction force of the movable member 31 from the upstream direction overcomes the above-described moving force of the liquid in the upstream direction, and slightly from the upstream side to the discharge port 18 side. , And the movable member 31 also starts to bend into a concave shape in the upstream direction. That is, an unbalanced state between the upstream side and the downstream side of the bubble 40 occurs, in which the liquid in the liquid flow path 10 temporarily temporarily flows as a whole toward the discharge port 18.

At the timing immediately after that, the liquid flow path 10 is still blocked by the movable member 31 and the stopper 64 as a whole in the liquid flow path 10, and the portion of the liquid flow path 10 having the bubble generation region 11 Since the space is substantially closed except for the discharge port 18, the contraction energy of the bubble 40 acts strongly as a force for moving the liquid near the discharge port 18 in the upstream direction as an overall balance. Accordingly, the meniscus M is largely drawn into the liquid flow path 10 from the discharge port 18 at this time, and the liquid column connected to the discharge liquid droplet 66 is quickly separated with a strong force. As a result, FIG.
As shown in (d), the number of droplets, that is, satellites (sub-droplets) 67 left outside the discharge port 18 is reduced. Further, as described above, the movable member 31 and the stopper 64 separate the upstream and downstream of the liquid flow path 10 from the movable member 31.
Has a step of bending into a concave shape, thereby enabling an initial movement of the liquid in the refill direction before the main refill is started. As a result, refilling is performed stably and promptly, so that a sufficient contribution can be made to the formation of the next ejection droplet.

In FIG. 1D, the defoaming step is almost completed,
This shows a state in which the ejection droplet 66 and the meniscus M are separated. In the low flow path resistance region 65, the downward displacement of the movable member 31 and the accompanying displacement in the low flow path resistance region 65 are caused by the repulsive force of the movable member 31 and the contraction force of the bubbles 40 against the moving force of the liquid in the upstream direction. The flow in the downstream direction is started, and the contact state between the movable member 31 and the stopper 64 starts to be released. Along with this, the flow in the downstream direction in the low flow resistance region 65 has a small flow resistance, so that it quickly becomes a large flow and the stopper 6
The liquid flows into the liquid flow path 10 through four parts. As a result, the flow of rapidly pulling the meniscus M into the liquid flow path 10 suddenly drops, so that the meniscus M remains outside from the discharge port 18 or is convex in the direction of the discharge port 18. Starts returning to the position before foaming at a relatively low speed while taking in as little as possible. In particular, when the meniscus M return flow and refill from the upstream merge, the discharge port 1
Since a region where the flow velocity is almost zero can be formed between the heating element 8 and the heating element 2, the convergence of the meniscus M is good. Although this depends on the viscosity and surface tension of the ink, according to the present invention, this liquid column separates and becomes a satellite and adheres to the printed matter, deteriorating the image quality, or adheres near the orifice and adversely affects the ejection direction. And that which causes ejection failure can be drastically reduced.

The meniscus M itself is also large,
Since the recovery is started before being drawn into 0, the recovery is achieved in a short time even if the liquid moving speed itself is not so high. For this reason, the overshoot of the meniscus M, that is, the amount of protrusion toward the outside of the discharge port 18 without stopping at the discharge port 18 is reduced, and the damping vibration having the discharge port 18 generated following the overshoot as a convergence point is achieved. The phenomenon can be completed in a very short time. Since the damped vibration phenomenon also has an adverse effect on print quality, the present invention enables stable high-speed printing.

The movable member 31 and the stopper 6
As shown in FIG. 1D, the flow of the liquid into the liquid flow path 10 through the portion between the portions 4 is to increase the flow velocity on the wall surface on the top plate 50 side. Residue is extremely small, which contributes to ejection stability.

On the other hand, some of the satellites 67 immediately following the ejected droplet 66 are very close to the ejected droplet 66 due to the rapid meniscus retraction in FIG. A phenomenon of receiving a force attracted to the ejection droplet 66 by the vortex of air generated behind, that is, a so-called slip stream phenomenon occurs.

This phenomenon will be described in detail. In a conventional liquid discharge head, a droplet does not form a sphere at the moment when the liquid is discharged from the discharge port, but is discharged in a state close to a liquid column having a spherical portion at the tip. It is known that when the tail portion is pulled by both the main droplet and the meniscus and is separated from the meniscus, satellite dots are formed from the tail portion and fly to the recording medium together with the main droplet. . Since the satellite dot flies later than the main droplet, the ejection speed is low by the amount of being pulled by the meniscus, and the landing position is shifted from the main droplet, deteriorating the print quality. In the liquid ejection head according to the present invention,
As described above, since the force for retracting the meniscus is greater than that of the conventional liquid ejection head, the force for pulling the tail portion after the main droplet has been ejected is strong, and the force for separating the meniscus from the tail portion is increased. Timing is also faster. Therefore, the satellite dots formed from the trailing portion are small, and the distance between the main droplet and the satellite dots is short. Further, since the tail portion is not continuously pulled by the meniscus, the ejection speed does not decrease, and the satellite 67 is drawn behind the ejection droplet 66 by a so-called slip stream phenomenon.

FIG. 1E shows a state in which the state of FIG. 1D is further advanced. The satellite 67 further discharges droplets 66
At the same time, and the attraction force due to the slip stream phenomenon also increases. On the other hand, the discharge port 18 from the upstream side
The liquid is moved downward from the initial position by the completion of the defoaming process of the bubble 40 and the displacement overshoot of the movable member 31, thereby drawing the liquid from the upstream side and discharging the liquid from the discharge port 18.
This causes the liquid to be pushed in the direction. In addition, the liquid flow in the direction of the discharge port 18 increases due to the enlargement of the cross-sectional area of the liquid flow path 10 in which the stopper 64 exists, and the return of the meniscus M to the discharge port 18 is accelerated. As a result, the refill characteristics in this embodiment are dramatically improved.

In addition, when cavitation occurs at the time of the disappearance of bubbles, the bubble disappearance point and the discharge port 18 are separated by the downward displacement of the movable member 31, so that the shock wave due to cavitation is not directly transmitted to the discharge port 18 and the movable member 31 Absorbed much. As a result, microdroplets called microdots generated from the meniscus M when the shock wave due to cavitation reaches the meniscus M almost disappear, so that the microdots are attached to the printed matter to lower the image quality, or the vicinity of the discharge port 18 is reduced. The phenomenon that the ink adheres to the ink and makes the ejection unstable is drastically reduced.

Further, the point at which cavitation occurs due to defoaming is also shifted to the fulcrum 33 side by the movable member 31, so that damage to the heating element 2 is reduced. Further, forced movement of the thickened ink between the movable member 31 and the heating element 2 is caused, and the ink is removed from the closed area, thereby improving the ejection durability. At the same time, due to the same phenomenon, sticking of burns to the heating element 2 in this region is reduced, so that ejection stability is improved.

FIG. 1F shows a state in which the state of FIG. 1E is further advanced, and the satellite 67 is taken into the discharged droplet 66. The union of the ejection droplet 66 and the satellite 67 is not necessarily a phenomenon that occurs every ejection in other embodiments,
It may or may not occur depending on conditions. However, by reducing or eliminating the amount of the satellite 67 at least, the landing position of the main droplet and the satellite dot hardly shifts on the recording medium, and the influence on the print quality is extremely reduced. That is, the sharpness of the image can be increased and the print quality can be improved, and at the same time, it is possible to reduce adverse effects such as mist that stains the print medium and the inside of the recording apparatus.

On the other hand, the movable member 31 is again displaced in the direction of the stopper 64 by its elastic force. That is, the movable member 31 starts returning to the original position by overcoming various forces generated in the liquid flow path 10. And ultimately,
As shown in FIG. 1 (g), the movable member 31 has a free end 31.
Stops at the initial position where it contacts the stopper 64. At this time, the meniscus M has already returned in the vicinity of the discharge port 18. However, even after the movable member 31 returns to the initial position and shuts off the liquid flow path 10, the side end of the movable member 31 and the liquid flow path partition wall 101 remain in contact with each other. When the meniscus M has not completely returned, the liquid can slightly pass through the gap between them, and assists refilling.

When the movable member 31 returns to the initial position, the flow of the liquid from the common liquid chamber 13 to the discharge port 18 is controlled, and the movement of the meniscus M quickly converges near the discharge port 18. Here, since the liquid flow path 10 is in the cutoff state, the overshoot phenomenon of the meniscus M and the like can be prevented.
Factors which make the ejection state unstable and lower the print quality can be greatly reduced.

In the series of operations of the movable member 31 described above, when the bubble 40 grows, the movable member 31 bends in a convex shape, so that the heat generation characteristics of the heating element 2 vary and the surrounding temperature changes. Even if the foaming state varies, this variation in the foaming state is absorbed by the curvature of the movable member 31. Therefore, it is possible to suppress the variation in the ejection amount due to the variation in the foaming state.

Next, further characteristic effects of the present embodiment will be described.

FIG. 2 is a perspective view of a part of the head shown in FIG. 1B, and shows basically the same state as that of FIG. is there. In the present embodiment, there is a slight clearance (gap) between both side walls of the wall constituting the liquid flow path 10 and both side portions of the movable member 31 to enable the convex member of the movable member 31 and the passage of liquid. ing. Further, in the growth step of foaming by the heating element 2, the air bubbles 40 curve the movable member 31 into a convex shape and protrude to the upper surface side of the movable member 31 via the clearance to slightly enter the low flow path resistance region 65. . The intruded raised bubbles 41 wrap around the back surface of the movable member 31 (the surface opposite to the surface facing the bubble generation region 11), thereby suppressing blurring of the movable member 31 and stabilizing the ejection characteristics.

Further, in the defoaming step of the bubbles 40, the raised bubbles 41 are moved from the low flow resistance region 65 to the bubble generation region 11.
In combination with the above-described high-speed meniscus pull-in from the discharge port 18 side, the defoaming is completed promptly. In particular, bubbles are hardly stored in the movable member 31 and the corners of the liquid flow path 10 due to the liquid flow caused by the raised bubbles 41.

As described above, in the liquid discharge head having the above structure, at the moment when the liquid is discharged from the discharge port due to the generation of bubbles, the discharged droplet is discharged in a state close to a liquid column having a spherical portion at the tip. Although this is the same in the conventional head structure, in the present invention, in the bubble growth step, the movable member comes into contact with the stopper to block the liquid flow path, and the liquid flow path includes the bubble generation region. However, the space is substantially closed except for the discharge port. Therefore, if the bubbles are eliminated in this state, the movable member is stopped by the defoaming (regulator).
Until further away, the above-described closed space is maintained, so that most of the defoaming energy of the bubbles acts as a force for moving the liquid near the discharge port in the upstream direction. As a result, immediately after the start of bubble defoaming, the meniscus is rapidly drawn into the liquid flow path from the discharge port, and the tail portion connected to the discharged liquid droplet outside the discharge port to form a liquid column is a meniscus. It is quickly separated by stronger force. As a result, satellite dots formed from the trailing portion become smaller, and the ejection amount is stabilized, so that print quality can be improved.

Further, since the tailing portion is not continuously pulled by the meniscus M, the ejection speed does not decrease, and the distance between the ejection droplet and the satellite dot is shortened. Attracts satellite dots. as a result,
Merging of the ejected droplets and satellite dots can occur, and it is possible to provide a liquid ejecting head having almost no satellite dots.

Further, the present invention is characterized in that, in the above-described head, the movable member is provided to suppress only bubbles that grow in the upstream direction with respect to the flow of the liquid toward the discharge port. More preferably, the free end of the movable member is located substantially at the center of the bubble generation region. According to this configuration, it is possible to suppress the back wave to the upstream side due to bubble growth and the inertial force of the liquid, which are not directly related to the ejection of the liquid, and to directly direct the growth component to the downstream side of the bubble toward the ejection port. It is possible.

Further, the present invention is characterized in that, in the above-described head, the flow path resistance of the liquid flow path on the opposite side of the discharge port with respect to the regulating portion is low. According to this configuration, since the movement of the liquid in the upstream direction due to the growth of the bubbles becomes a large flow by the liquid flow path having the low flow path resistance, the movable member receives the stress in the form pulled in the upstream direction. Become.
As a result, even if defoaming is started in this state, since the liquid moving force in the upstream direction due to the growth of bubbles remains largely, the repulsive force of the movable member and the negative pressure at the time of defoaming are superior to this liquid moving force. The above-mentioned closed space can be maintained for a certain period of time. That is, with this configuration, the high-speed meniscus retraction is more reliable. In addition, the bubble defoaming step proceeds, and when the repulsive force of the movable member and the negative pressure at the time of defoaming exceed the liquid moving force in the upstream direction due to bubble growth, the movable member is displaced downward while concavely curved, Accordingly, a flow in the downstream direction occurs even in the low flow path resistance region. Since the flow in the downstream direction in the low flow resistance region has a low flow resistance, the flow quickly becomes a large flow and flows into the liquid flow passage via the regulating portion. As a result, due to the liquid movement in the downstream direction toward the discharge port, the above-described meniscus retraction can be suddenly braked, and the vibration of the meniscus can be quickly converged.

As described above, in the liquid discharge head of the present invention, the movable member 31 is brought into contact with the stopper 64 in the initial state where the bubbles 40 are not generated, so that the liquid from the upstream in the defoaming stage is discharged. Restrict the flow,
The rapid pull-in of the meniscus M into the liquid flow path 10 is achieved.

In order to effectively restrict the flow of liquid from upstream in the defoaming stage, the movable member 31 is not displaced downward by a force generated in the liquid flow path 10 from upstream to downstream at the beginning of the defoaming stage. It is desirable. That is, the movable member 31
It is preferable that the displacement does not start immediately after the defoaming stage starts, but starts after a time lag. Therefore, in the present embodiment, the movable member 31 is elastically deformed and the stopper 6
4 and the movable member 31 is pressed against the stopper 64 with a certain force.

That is, the element substrate 1 shown in FIG.
The height H from the surface of the element substrate 1 to the tip of the movable member 31 in a state before the bonding between the element substrate 1 and the top plate 50 before the bonding between the element substrate 1 and the top plate 50 shown in FIG. The movable member 31 is formed to be inclined with respect to the surface of the element substrate 1 such that the free end side of the movable member 31 is lifted so as to be larger than the height h from the surface of the element substrate 1 to the stopper 64.

As described above, the movable member 31 is formed on the element substrate 1 and the element substrate 1 and the top plate 50 are joined to each other. It is displaced and is in contact with the stopper 64. Therefore, as long as the force due to the large flow of the liquid from upstream to downstream does not act on the movable member 31, the movable member 31
4, the liquid flow path 10 can be reliably shut off between the downstream side including the bubble generation region 11 and the upstream side not including the bubble generation region 11. In addition, since the position of the movable member 31 is determined by being pressed by the stopper 64, the tip position of the movable member 31 can be arbitrarily set by changing the height of the stopper 64.

Further, the downward displacement of the movable member 31 at the time of defoaming is performed by further elastic displacement of the movable member 31, so that the inside of the movable member 31 generated when the movable member 31 is displaced to the lowest position. Stress can be increased. As a result, the restoring force in the state where the movable member 31 is displaced downward can be increased, and the operation of the movable member 31 after refilling the liquid, that is, the return operation from the lowest position to the initial position is performed at high speed. be able to.

From the viewpoint of performing the returning operation of the movable member 31 at a high speed, the ratio of the height from the surface of the element substrate 1 to the tip of the movable member 31 before and after joining the element substrate 1 and the top plate 50 is determined. H / h is preferably large. However, H / h
Is too large, it is difficult for the movable member 31 to be displaced downward. Therefore, H / h is designed in consideration of the force acting on the movable member 31 at the time of defoaming, the elastic modulus of the movable member 31, and the like. Is preferred.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
It is a schematic diagram which shows embodiment. In addition, FIG.
(G) is shown corresponding to FIGS. 1 (a) to (g), and the description of the same configuration is omitted. FIG. 4 (h)
FIG. 4 is a sectional view taken along line AA of FIG.

In this embodiment, in the vicinity of the bubble generation region 11, the movable member 31 has the convex portion 3 protruding toward the element substrate 1.
1c (hereinafter, referred to as “lower convex portion 31c”) and the top plate 50 restrict the displacement of the movable member 31 on both sides of the liquid flow path 10 downstream of the stopper 64. The difference from the first embodiment is that a side stopper (side regulation portion) 63 is provided.

The lower protruding portion 31c suppresses the growth of bubbles generated in the bubble generation region 11 rearward (upstream side). By providing the lower protruding portion 31c,
FIG. 4B shows that the backward growth of the bubbles 40 is smaller than in the first embodiment. And
The lower protruding portion 31c contributes to improving the ejection energy by suppressing the growth of the bubbles 40 in the rearward direction.

When the movable member 31 is displaced toward the element substrate 1 as shown in FIG.
As shown in (e), the lower protruding portion 31c may come into contact with the element substrate 1; therefore, it is preferable that the lower protruding portion 31c be located at least at a position apart from a step portion around the heating element 2. Specifically, it is desirable to be at least 5 μm away from the effective foaming area. Also, if it is too far from the bubble generation area 11,
Since the effect of suppressing the backward growth of the bubbles 40 cannot be sufficiently exhibited, the heating element 2 is moved from the effective foaming region of the heating element 2 to the heating element 2.
Is preferably provided within a distance of up to approximately half of the length of. That is, in the present embodiment, it is set to 45 μm, preferably within 30 μm, more preferably 20 μm.
m. The height of the lower convex portion 31c is substantially equal to or less than the distance between the movable member 31 and the element substrate 1 when the movable member 31 is parallel to the surface of the element substrate 1. In the present embodiment, in the above state, the lower protrusion 31
The height has a slight clearance between the element c and the element substrate 1.

The lower convex portion 31c suppresses the growth of the bubble 40 generated in the bubble generation region 11 in the upstream direction between the movable member 31 and the element substrate 1, thereby preventing the liquid from moving in the upstream direction. As a result, the refill of the liquid can be further improved.

Further, by providing the side stopper 63, the sealed state of the bubble generation region 11 can be further improved, and the side wall of the flow path and the movable member 31 can be improved.
, And the displacement of the movable member 31 at the time of defoaming can be made smoother. In the present embodiment, the lower projection 31c and the side stopper 63 are both provided.
These may be used alone, in which case they exhibit their own effects.

(Other Embodiments) Hereinafter, various embodiments applicable to a head using the above-described liquid discharging method will be described.

<Movable Member> FIG. 5 shows various shapes of the movable member 31. FIG. 7A shows a movable member 31 having a rectangular shape, FIG. 7B shows a shape in which the fulcrum side is thin and the movable member 31 is easy to operate, and FIG. The movable member 31 has a shape that increases in rigidity.

In the above embodiment, the movable member 31 is made of nickel having a thickness of 3 μm. However, the material of the movable member 31 is not limited to this and has solvent resistance to the discharge liquid. The movable member 31 only needs to have elasticity to operate well.

As the material of the movable member 31, silver, nickel, gold, iron, titanium, aluminum,
Metals such as platinum, tantalum, stainless steel, phosphor bronze, and alloys thereof, or acrylonitrile, butadiene,
Resin having a nitrile group such as styrene, resin having an amide group such as polyamide, resin having a carboxyl group such as polycarbonate, resin having an aldehyde group such as polyacetal, resin having a sulfone group such as polysulfone, and other liquid crystal polymers. Resins and their compounds,
Metals such as gold, tungsten, tantalum, nickel, stainless steel, titanium, etc., which have high ink resistance, alloys of these, and those with ink resistance coated on the surface, resins having amide groups such as polyamide, polyacetal, etc. Resin having an aldehyde group, resin having a ketone group such as polyetheretherketone, resin having an imide group such as polyimide, resin having a hydroxyl group such as a phenol resin, resin having an ethyl group such as polyethylene, and alkyl such as polypropylene. Resin with groups,
Resins having an epoxy group such as an epoxy resin, resins having an amino group such as a melamine resin, resins having a methylol group such as a xylene resin and compounds thereof, and ceramics such as silicon dioxide and silicon nitride and compounds thereof are desirable.
The movable member 31 in the present invention has a thickness on the order of μm.

Next, the positional relationship between the heating element and the movable member will be described. By the optimal arrangement of the heating element and the movable member,
The flow of the liquid at the time of foaming by the heating element can be appropriately and controlled to be used effectively.

Here, the area (or foam area) of the heating element
The relationship between and the ink ejection amount will be described with reference to FIG. By giving energy such as heat to the ink, a state change accompanied by a steep volume change (bubble generation) is caused in the ink, and the ink is ejected from the ejection port by an action force based on this state change, and this is recorded. In the related art of an ink jet recording method of forming an image by adhering onto a medium, that is, a so-called bubble jet recording method, as shown by a broken line in FIG. It is found that there is a non-foaming effective area S which does not contribute to the above. In addition, from the appearance of the kogation on the heating element, it can be seen that the non-foaming effective area S exists around the heating element. From these results, about 4
The μm width is not considered to be involved in foaming. On the other hand, in the liquid discharge head of the present invention, since the liquid flow path is blocked by the movable member and the restricting portion, and the maximum discharge amount is regulated thereby, as shown by the solid line in FIG. There is a region where the discharge amount does not change even if the variation in the foaming volume is large. By using this region, the discharge amount can be stabilized.

Further, in order to form the above-mentioned substantially closed space well, it is preferable that the distance between the movable member and the heating element in the standby state is 10 μm or less.

<Element Substrate> Next, the configuration of the element substrate will be described.

FIG. 7 is a longitudinal sectional view of the liquid discharge head of the present invention. FIG. 7A shows a head having a protective film described later, and FIG. 7B shows a head without the protective film.

A top plate 50 provided with a liquid flow path 10, a discharge port 18 communicating with the liquid flow path 10, a low flow path resistance region 65, and a groove forming the common liquid chamber 13 is provided on the element substrate 1. .

The element substrate 1 has a base 107 made of silicon or the like.
A silicon oxide film or a silicon nitride film 106 for the purpose of insulation and heat storage is formed thereon, and hafnium boride (HfB ₂ ), tantalum nitride (TaN), tantalum aluminum ( An electric resistance layer 105 (having a thickness of 0.01 to 0.2 μm) such as TaAl) and a wiring electrode 104 (having a thickness of 0.2 to 1.0 μm) such as aluminum are patterned as shown in FIG. 7A. A voltage is applied from the wiring electrode 104 to the resistance layer 105, and a current flows through the resistance layer to generate heat. On the resistance layer between the wiring electrodes, a protective layer 103 of silicon oxide, silicon nitride,
It is formed to a thickness of 2.0 μm, and further has a cavitation-resistant layer 102 of tantalum or the like (0.1 to 0.6 μm thick)
Is formed on the resistive layer 1 from various liquids such as ink.
05 is protected.

In particular, the pressure and shock waves generated during the generation and defoaming of air bubbles are very strong, and the durability of a hard and brittle oxide film is significantly reduced.
Are used as the anti-cavitation layer 102.

In addition, a configuration in which the protective layer 103 is not required for the above-described resistance layer 105 may be employed depending on the combination of the liquid, the liquid flow path configuration, and the resistance material. An example is shown in FIG.
Examples of the material of the resistance layer 105 that does not require the protective layer 103 include an iridium-tantalum-aluminum alloy.

As described above, the configuration of the above-mentioned heating element may be only the above-described resistance layer (heating section) between the electrodes.
Further, it may include a protective layer for protecting the resistance layer.

Here, a heating element having a heating portion composed of a resistance layer that generates heat in accordance with an electric signal is used as the heating element. However, the present invention is not limited to this. What is necessary is just to generate | occur | produce in a foaming liquid.
For example, a light-to-heat converter that generates heat by receiving light from a laser or the like, or a heat generator that has a heat generating unit that generates heat by receiving a high frequency may be used as the heat generating unit.

The above-mentioned element substrate 1 has, in addition to the above-mentioned electrothermal transducer composed of the resistance layer 105 constituting the above-mentioned heat generating portion and the wiring electrode 104 for supplying an electric signal to this resistance layer, Functional elements such as a transistor, a diode, a latch, and a shift register for selectively driving the electrothermal conversion element may be integrally formed by a semiconductor manufacturing process.

Further, in order to drive the heat generating portion of the electrothermal transducer provided on the element substrate 1 and discharge the liquid, the above-described resistance layer 105 is connected to the above-described resistance layer 105 through the wiring electrode 104 as shown in FIG. A rectangular pulse as shown by is applied to cause the resistance layer 105 between the wiring electrodes to generate heat sharply. In the head of each of the above-described embodiments, the voltage is 24 V, the pulse width is about 4 μsec, the current is about 100 mA, and the electric signal is 6 kHz.
The heating element was driven by the addition described above, and the liquid ink was ejected from the ejection port by the operation described above. However, the condition of the drive signal is not limited to this, and any drive signal can be used as long as it can appropriately foam the foaming liquid.

<Discharged Liquid> Among such liquids, as a liquid (recording liquid) used for recording, an ink having a composition used in a conventional bubble jet apparatus can be used.

Also, liquids having low foaming properties, which have been difficult to discharge in the past, liquids which are easily deteriorated or deteriorated by heat, and high viscosity liquids can be used.

However, the properties of the discharged liquid are as follows:
It is desired that the liquid is not a liquid that hinders ejection, foaming, operation of the movable member, and the like.

As the ejection liquid for recording, a high-viscosity ink or the like can also be used.

In the present invention, recording was performed using an ink having the following composition as a recording liquid that can be used as the discharge liquid. However, since the discharge speed of the ink was increased due to the improvement of the discharge force, the liquid was discharged. Drop landing accuracy is improved, and a very good recorded image can be obtained.

Composition of Dye Ink (Viscosity 2 cP) (C-1. Food Black 2) Dye 3 wt% Diethylene glycol 10 wt% Thiodiglycol 5 wt% Ethanol 5 wt% Water 77 wt%

<Liquid Discharge Head Structure> FIG. 9 is an exploded perspective view showing the entire configuration of the liquid discharge head of the present invention.

An element substrate 1 provided with a plurality of heating elements 2 on a support 70 made of aluminum or the like is arranged. A support member 34 supporting the movable member 31 is provided on the heating member 2 so as to face a half of each heating element 2 on the common liquid chamber 13 side. Further, a top plate 50 provided with a plurality of grooves constituting the liquid flow path 10 and a concave groove of the common liquid chamber 13 is provided thereon.
As can be seen from FIG. 9, the movable member 31 is formed obliquely with its tip end lifted.

<Side shooter type> Here, FIG.
The liquid ejection principle described with reference to FIG. 2 is applied to a side shooter type head in which a heating element and an ejection port face each other on a parallel plane. FIG. 10 is a view for explaining this side shooter type head.

In FIG. 10, the heating element 2 on the element substrate 1
The discharge port 18 formed on the top plate 50 is disposed so as to face the discharge port 18. The discharge port 18 communicates with the liquid flow path 10 passing over the heating element 2. A bubble generation region exists in a region near the surface where the heating element 2 contacts the liquid. And the element substrate 1
On top of which two movable members 31 are supported, each movable member 3
1 is formed so as to be plane-symmetric with respect to a plane passing through the center of the heating element (center plane), and the free ends of the respective movable members 31 are positioned so as to face each other on the heating element 2. Also,
Each movable member 31 has the same projected area on the heating element 2, and the free ends of each movable member 31 are separated by a desired size. Here, assuming that each movable member 31 is divided by a plane (center plane) passing through the center of the heating element 2,
A movable member 3 is provided near the center of each divided heating element 2.
It is provided so that one free end is located.

The top plate 50 is provided with a stopper 64 for blocking the flow path with each movable member 31. The tip of each movable member 31 is in contact with the stopper 64 in the initial state where no bubbles 40 are generated. are doing. In the flow of the liquid from the common liquid chamber 13 to the discharge port 18, a low flow resistance region 65 having a lower flow resistance than the liquid flow path 10 is provided upstream of the stopper 64. I have. The flow path structure in this region 65 has a larger flow path cross-sectional area than the liquid flow path 10, so that the resistance received from the flow path to the movement of the liquid is reduced.

Next, the characteristic action of the structure of the present embodiment will be described.
The effect will be described.

FIG. 10A shows a state in which a part of the liquid filling the bubble generation region 11 is heated by the heating element 2 and the bubbles 40 accompanying film boiling have grown to the maximum. Since the movable member 31 is already in contact with the stopper 64 before the bubble 40 is generated, the liquid in the liquid flow path 10 moves toward the discharge port 18 by the pressure based on the generation of the bubble 40, Due to the growth of 40, each movable member 31 is curved convexly toward the common liquid chamber 13 side,
Is about to jump out. Here, the movement of the liquid in the direction of the common liquid chamber 13 becomes a large flow due to each low flow path resistance region 65, but the two movable members 31 are each curved in a convex shape,
Since further displacement is regulated, the movement of the liquid in the direction of the common liquid chamber 13 is also greatly restricted there. Bubbles 4 at the same time
The growth to the upstream side of 0 is also restricted by the movable member 31. However, since the moving force of the liquid in the upstream direction is large, a part of the bubble 40 whose growth is restricted by each movable member 31 causes a gap between the side wall forming the liquid flow path 10 and the side of the movable member 31. As a result, the upper surface of the movable member 31 protrudes. That is, the raised bubble 41 is formed.

When the contraction of the bubble 40 is started after the film boiling, at this point, a large force in the upstream direction of the liquid remains, so that each movable member 31 is in contact with the stopper 64 and the bubble 40 Most of the contraction causes the liquid to move from the discharge port 18 in the upstream direction. Therefore, the meniscus is largely drawn into the liquid flow path 10 from the discharge port 18 at this time, and quickly separates the liquid column connected to the discharge droplet 66 with a strong force. As a result, the number of droplets left outside the discharge port 18, that is, satellites, is reduced.

As the defoaming step progresses, the movable member 31 in each low flow path resistance region 65 reacts to the moving force of the liquid in the upstream direction.
Repulsive force (restoring force) and negative pressure at the time of defoaming prevail, moving member 3
The downward displacement of 1 and the accompanying downstream flow in the low flow resistance region 65 are started. At the same time, since the flow in the downstream direction in the low flow resistance region 65 has a low flow resistance, the flow rapidly becomes a large flow and flows into the liquid flow passage 10 through the stopper 64. FIG. 10B shows the liquid flow in the bubble erasing step of the bubble 40 by AB. The liquid flow A indicates a component in which the liquid from the common liquid chamber 13 flows toward the discharge port 18 through the upper surface (the surface opposite to the heating element) of the movable member 31, and the liquid flow B indicates both components of the movable member 31 and the heating element. 2 shows the components flowing over the top.

As described above, in the present embodiment, the refilling property is increased at a higher speed by supplying the ejection liquid from the low flow path resistance region 65. Further, since the common liquid chamber 13 adjacent to the low flow path resistance region 65 further reduces the flow path resistance, high-speed refilling is possible.

Further, in the defoaming step of the bubbles 40, the raised bubbles 41 are moved from the low flow resistance regions 65 to the bubble generation regions 1.
1 is accelerated, and the defoaming is quickly completed in combination with the above-described high-speed meniscus pulling in from the discharge port 18 side. In particular, bubbles are hardly stored in the movable member 31 and the corners of the liquid flow path 10 due to the liquid flow caused by the raised bubbles 41.

Further, the present invention suppresses a change in the discharge amount due to the difference in the foaming state due to the surface state of the heating element and a change in the discharge amount due to the temperature by forming the movable member into a convex shape at the stage of the bubble growth. Is possible.

Although the movable member 31 has a simple plate shape as an example, the side shooter type liquid ejection head can also be used for the bubble 40 as described in the second embodiment. A protrusion that regulates the growth in the upstream direction may be provided on the movable member 31 so as to protrude toward the element substrate 1.

<Liquid Discharge Apparatus> FIGS.
1 shows a schematic configuration of a liquid ejection apparatus equipped with a liquid ejection head having the structure described in FIG. In the present embodiment, an explanation will be given using an ink discharge recording apparatus using ink as the discharge liquid. The carriage HC of the liquid discharge device includes a liquid tank unit 90 for storing ink and a liquid discharge head unit 200.
And a recording medium 1 such as a recording paper conveyed by a recording medium conveying means.
It reciprocates in the width direction of 50.

When a drive signal is supplied from a drive signal supply means (not shown) to the liquid discharge means on the carriage, the recording liquid is discharged from the liquid discharge head to the recording medium in accordance with this signal.

Further, in the liquid discharge apparatus of the present embodiment, the motor 111 as a drive source for driving the recording medium transport means and the carriage, the gears 112 and 113 for transmitting the power from the drive source to the carriage, It has a carriage shaft 115 and the like. With this recording apparatus and the liquid ejection method performed by this recording apparatus, a recorded matter of a good image could be obtained by ejecting liquid to various recording media.

FIG. 12 is a block diagram of the entire apparatus for operating ink discharge recording in the liquid discharge method and liquid discharge head of the present invention.

The printing apparatus receives print information from the host computer 300 as a control signal. The print information is temporarily stored in an input interface 301 inside the printing apparatus, and at the same time, is converted into data that can be processed in the printing apparatus, and is input to the CPU 302 also serving as a head drive signal supply unit. The CPU 302 processes data input to the CPU 302 using a peripheral unit such as the RAM 304 based on a control program stored in the ROM 303,
Convert to print data (image data).

The CPU 302 generates drive data for driving a drive motor for moving the recording paper and the recording head in synchronization with the image data in order to record the image data at an appropriate position on the recording paper. . The image data and the motor drive data are respectively stored in the head driver 307
Is transmitted to the head 200 and the drive motor 306 via the motor driver 305, and is driven at controlled timing to form an image.

The recording medium which can be applied to the above-described recording apparatus and to which a liquid such as ink is applied includes plastics, cloth, aluminum, etc. used for various papers, OHP sheets, compact discs and decorative plates, and the like. Metal materials such as copper and copper, leather materials such as cow skin, pig skin and artificial leather, wood such as wood and plywood, ceramic materials such as bamboo materials and tiles, and three-dimensional structures such as sponges can be targeted.

As the above-mentioned recording device, a printer device for recording on various types of paper and OHP sheets, a recording device for plastic for recording on plastic materials such as compact disks, and a metal recording device for recording on a metal plate. Recording device, recording device for leather for recording on leather, recording device for wood for recording on wood, recording device for ceramics for recording on ceramic materials, recording device for recording on three-dimensional net structures such as sponges And a textile printing apparatus for recording on a fabric.

As the discharge liquid used in these liquid discharge devices, a liquid suitable for each recording medium and recording conditions may be used.

[0128]

As described above, in the case where the movable member is convexly curved in a state where the liquid flow path is substantially divided into the upstream and the downstream in the process of growing the bubble, the curvature of the movable member causes In addition, it is possible to suppress variations in the discharge amount due to variations in the foaming state. In particular, in this case, the convexly curved portion is concavely curved by the elastic force of the movable member itself during the bubble contraction step, so that the liquid can be stably and quickly refilled into the liquid flow path.

In the case where the movable member comes into contact with the regulating portion by the elastic force of the movable member to divide the liquid flow path into upstream and downstream, the movable member starts displacing after a lapse of time from the defoaming stage. As a result, the meniscus can be rapidly drawn into the discharge port, thereby preventing satellite dots and stabilizing the discharge amount.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a liquid discharge head according to a first embodiment of the present invention cut in a liquid flow direction, and characteristic phenomena in a liquid flow path are described in steps (a) to (g). It is shown separately.

FIG. 2 is a perspective view of a part of the head shown in FIG. 1 (b).

FIG. 3 is a view for explaining the position of a movable member of the liquid ejection head shown in FIG. 1 before and after joining an element substrate and a top plate.

FIGS. 4A to 4G are views for explaining a liquid discharge head according to a second embodiment of the present invention, wherein FIG. 4A to FIG. Sectional view at (h)
FIG. 3 is a sectional view taken along line AA of FIG.

FIG. 5 shows another shape of the movable member shown in FIG.

FIG. 6 is a graph showing a relative relationship between a heating element area and an ink ejection amount.

FIGS. 7A and 7B are longitudinal sectional views of a liquid discharge head according to the present invention, in which FIG. 7A has a protective film and FIG. 7B does not.

FIG. 8 is a waveform diagram for driving a heating element used in the present invention.

FIG. 9 is an exploded perspective view showing the entire configuration of the liquid ejection head of the present invention.

FIG. 10 is a diagram for explaining a side shooter type head to which the liquid ejection method of the present invention is applied.

FIG. 11 is a diagram showing a schematic configuration of a liquid ejection apparatus equipped with the liquid ejection head having the structure described in FIG. 1 or FIG.

FIG. 12 is a block diagram of an entire apparatus for operating ink discharge recording in a liquid discharge method and a liquid discharge head of the present invention.

FIG. 13 is a cross-sectional view of a flow path illustrating a “linear communication state”.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Element board 2 Heating element 10 Liquid flow path 11 Bubble generation area 13 Common liquid chamber 18 Discharge port 31 Movable member 31c Lower convex part 32 Free end 33 Support point 34 Support member 40 Bubble 41 Raised bubble 50 Top plate 63 Side stopper (side) (Regulator) 64 Stopper 65 Low flow resistance region 66 Discharged droplet 67 Satellite 70 Support 90 Ink tank 102 Cavitation resistant layer 103 Protective layer 104 Wiring electrode 105 Resistive layer 106 Silicon nitride film 107 Base 111 Motor 112, 113 Gear 115 Carriage shaft 150 recording medium 200 head 300 host computer 301 input / output interface 302 CPU 303 ROM 304 RAM 305 motor driver 306 driving motor 307 head driver

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masao Mori 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Sadayuki Sugama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated F term (reference) 2C056 EA04 FA03 HA02 2C057 AF06 AF23 AF28 AF93 AG03 AG12 AG46 AG76 AP02 AP14 AP25 BA03 BA13

Claims (24)

[Claims] 1. A heating element for generating thermal energy for generating bubbles in a liquid, a discharge port from which the liquid is discharged, and a bubble generation region in which the bubbles are generated, and communicates with the discharge port. A liquid flow path, a cantilevered movable member provided to be displaceable in the bubble generation region, and a regulating portion provided to face the bubble generation region to regulate a displacement range of the movable member, A liquid ejection head that ejects the liquid from the ejection port with energy at the time of generation of bubbles, wherein the movable member contacts the regulating unit in an initial state where the bubbles are not generated, and the liquid flow path Is substantially divided into a downstream side including the bubble generation region and an upstream side not including the bubble generation region,
Before the bubble grows to the maximum, the liquid flow path is elastically convexly curved toward the upstream side with the liquid flow path being substantially cut off, and is displaced by the contraction force of the bubble defoaming to regulate the liquid flow path. A liquid discharge head that releases contact with a part. 2. The liquid discharge head according to claim 1, wherein the convexly curved portion of the movable member is concavely curved by the elastic force of the movable member at the time of the contraction of the bubble. . 3. A heating element for generating thermal energy for generating bubbles in the liquid, a discharge port from which the liquid is discharged, and a bubble generation region in which the bubbles are generated, and communicates with the discharge port. A liquid flow path, a cantilevered movable member provided to be displaceable in the bubble generation region, and a regulating portion provided to face the bubble generation region to regulate a displacement range of the movable member, A liquid ejection head that ejects the liquid from the ejection port using energy at the time of generation of bubbles, wherein the movable member is in an initial state in which the bubbles are not generated, and the movable member is moved to the regulating portion by elastic force of the movable member. In contact, the liquid flow path is substantially divided into a downstream side including the bubble generation region and an upstream side not including the bubble generation region, and is displaced by the contraction force of the defoaming of the bubbles to release the contact with the regulating portion. Liquid characterized by the following: Out head. 4. A liquid flow path having the bubble generation region is formed by joining a top plate member having the discharge port and the regulating portion to a substrate member having the heating element and the movable member. The distance from the surface of the substrate member before the bonding of the top plate member and the substrate member to a portion that is in contact with the regulating portion of the movable member is determined after the bonding of the top plate member and the substrate member. 4. The liquid ejection head according to claim 3, wherein the distance is larger than a distance from a surface of the substrate member to the regulating portion. 5. The moving member according to claim 1, further comprising a convex portion protruding in a portion adjacent to the bubble generation region, the convex portion protruding to a side opposite to the restricting portion. Item 2. The liquid discharge head according to item 1. 6. The liquid discharge head according to claim 1, wherein the heating element and the discharge port are in a linear communication state. 7. The apparatus according to claim 1, wherein the movable member is provided to suppress only bubbles that grow in an upstream direction with respect to a flow of the liquid toward the discharge port. 3. The liquid ejection head according to item 1. 8. The apparatus according to claim 1, wherein the movable member has a free end, and the free end is located substantially at a center of the bubble generation region. The liquid ejection head according to any one of the preceding claims. 9. The liquid ejection head according to claim 8, wherein the movable member is in contact with the regulating portion near the free end. 10. The method according to claim 1, wherein the flow path resistance of the liquid flow path is lower on the upstream side than on the downstream side with respect to the regulating portion as a boundary. Liquid ejection head. 11. The apparatus according to claim 1, wherein the restricting portion is formed by partially reducing a distance of the liquid flow path from the bubble generation region. The liquid ejection head according to any one of the preceding claims. 12. The liquid discharge head according to claim 1, wherein the discharge port is provided to face the heating element. 13. The method according to claim 13, wherein a plurality of the movable members are formed for one heating element, and the plurality of movable members are formed so as to be symmetrical with respect to a foaming center of the heating element. 13. The liquid ejection head according to claim 12, wherein: 14. A heating element for generating thermal energy for generating bubbles in a liquid, a discharge port from which the liquid is discharged, and a bubble generation region in which the bubbles are generated, and communicates with the discharge port. A liquid flow path, a cantilevered movable member provided to be displaceable in the bubble generation region, and a regulating portion provided to face the bubble generation region to regulate a displacement range of the movable member, A liquid ejection method using a liquid ejection head that ejects the liquid from the ejection port with energy at the time of generation of bubbles, wherein the movable member contacts the regulating portion in an initial state where the bubbles are not generated. Step of substantially dividing the liquid flow path into a downstream side including the bubble generation region and an upstream side not including the bubble generation region, and after the generation of the bubbles, before the bubbles grow to the maximum, the liquid flow paths In front of a practically divided state A step in which the movable member elastically bends convexly toward the upstream side; and, in the step of contracting the bubble, the movable member is displaced by the contraction force of the defoaming of the bubble to release the contact with the regulating portion. A liquid ejecting method. 15. The method according to claim 14, further comprising, before the movable member is displaced in the step of contracting the bubble, the convexly curved portion of the movable member is concavely curved by the elastic force of the movable member. The liquid discharging method according to the above. 16. A heating element for generating thermal energy for generating bubbles in a liquid, a discharge port from which the liquid is discharged, and a bubble generation region in which the bubbles are generated, and communicates with the discharge port. A liquid flow path, a cantilevered movable member provided to be displaceable in the bubble generation region, and a regulating portion provided to face the bubble generation region to regulate a displacement range of the movable member, A liquid ejection method using a liquid ejection head that ejects the liquid from the ejection port with energy at the time of generation of bubbles, wherein the movable member has an elastic force of the movable member in an initial state where the bubbles are not generated. A step of substantially dividing the liquid flow path into a downstream side including the bubble generation region and an upstream side not including the bubble generation region by contacting the regulating portion, By force Liquid discharging method characterized by a step of member is displaced to open the contact between the restricting portion. 17. The liquid discharging method according to claim 14, further comprising a step of shrinking the bubble while the movable member is in contact with the regulating portion. 18. In the step of shrinking the bubble while the movable member is in contact with the regulating portion, most of the movement of the liquid accompanying the shrinkage of the bubble is directed to the upstream direction from the discharge port, and the meniscus is adjusted to the meniscus. The liquid discharging method according to claim 17, wherein the liquid is rapidly drawn into the discharge port. 19. When the movable member is displaced to release contact with the regulating portion, a flow of liquid is generated in the bubble generation region in a downstream direction toward the discharge port, and the meniscus is drawn. The method according to claim 18, wherein sudden braking is performed. 20. A liquid, comprising: the liquid discharge head according to claim 1; and a recording medium transport unit that transports a recording medium that receives the liquid discharged from the liquid discharge head. Discharge device. 21. The liquid ejecting apparatus according to claim 20, wherein recording is performed by ejecting ink from the liquid ejecting head and attaching the ink to the recording medium. 22. A heating element for generating thermal energy for generating bubbles in the liquid, a discharge port from which the liquid is discharged, and a bubble generation region in which the bubbles are generated, and communicates with the discharge port. A liquid flow path, a cantilevered movable member provided to be displaceable in the bubble generation region, and a regulating portion provided to face the bubble generation region to regulate a displacement range of the movable member, A method for manufacturing a liquid ejection head that ejects the liquid from the ejection port by using energy at the time of generation of bubbles, wherein a step of preparing a top plate member including the ejection port and the regulating unit; A step of preparing a substrate member having a movable member, and a step of joining the top plate member and the substrate member to form the liquid flow path, wherein the top plate member and the substrate member are The joining process is A liquid that includes a step of substantially dividing the liquid flow path into a downstream side including the bubble generation region and an upstream side not including the bubble generation region by contacting the regulating portion in a state where the movable member is elastically deformed. A method for manufacturing a discharge head. 23. In the step of preparing the substrate member, a distance from a surface of the substrate member to a portion of the movable member that comes into contact with the restricting portion is the distance after joining the substrate member and the top plate member. 23. The method according to claim 22, wherein the distance is larger than a distance from a surface of the substrate member to the regulating portion. 24. The method according to claim 23, wherein in the step of joining the top plate member and the substrate member, the restricting portion presses the movable member.