JP2902137B2 - Ink flight recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus which is one of non-impact recording apparatuses.

[0002]

2. Description of the Related Art The non-impact recording method has attracted attention for office use and the like because noise generation during recording is small enough to be ignored. Among them, the so-called ink jet recording method, which is capable of high-speed recording and can record on so-called plain paper without requiring a special fixing process, is an extremely powerful method, and various methods have been conventionally proposed or already commercialized. Has been put to practical use.

In such an ink jet recording method, recording is performed by flying small droplets of a recording liquid called so-called ink and attaching the droplets to a recording medium. Depending on the control method for controlling the flight direction of the airplane, it is roughly classified into several types.

The first method is disclosed, for example, in US Pat.
It is disclosed in the specification. This is referred to as a Tele type method, in which droplets of the recording liquid are electrostatically attracted, the generated droplets are subjected to an electric field control according to a recording signal, and the droplets are placed on a recording medium. Is selectively attached to perform recording. More specifically, an electric field is applied between the nozzle and the accelerating electrode to discharge droplets of the uniformly charged recording liquid from the nozzle, and the discharged droplets can be electrically controlled in accordance with a recording signal. In this case, the droplets fly between the xy deflection electrodes and the small droplets are selectively deposited on the recording medium by a change in the intensity of the electric field.

[0005] A second method is disclosed, for example, in US Pat. No. 3,596,275.
And US Pat. No. 3,298,030. This is called a Sweet method, in which a droplet of the recording liquid whose charge amount is controlled by a continuous vibration generation method is generated, and the droplet whose charge amount is controlled is
The recording is performed on the recording medium by flying between the deflection electrodes to which a uniform electric field is applied. Specifically, a charging electrode to which a recording signal is applied is arranged at a predetermined distance in front of an orifice (ejection port) of a nozzle, which is a part of a recording head provided with a piezoelectric vibrating element. Then, by applying an electric signal of a constant frequency to the piezo-vibration element, the piezo-vibration element is vibrated mechanically, and a small droplet of the recording liquid is discharged from the orifice. At this time, a charge is electrostatically induced in the discharged droplet by the charging electrode, and the droplet is charged with a charge amount corresponding to the recording signal. The droplet whose charge amount is controlled is deflected according to the added charge amount when flying between the deflection electrodes to which a constant electric field is uniformly applied, and only the droplet carrying the recording signal is recorded on the recording medium. Will adhere to the top.

A third method is disclosed in, for example, US Pat. No. 3,416,153.
It is disclosed in the specification. This is Hearts
This is a method called an (Hertz) method, in which an electric field is applied between a nozzle and a ring-shaped charging electrode, and a continuous vibration generation method is used to generate and atomize small droplets of a recording liquid for recording. That is,
By modulating the intensity of the electric field applied between the nozzle and the charging electrode in accordance with the recording signal, the atomization state of the small droplet is controlled, and recording is performed with the gradation of the recorded image.

[0007] A fourth method is disclosed in, for example, US Pat. No. 3,747,120.
It is disclosed in the specification. This is called a steam (Stemme) system, and is fundamentally different in principle from the first to third systems. That is, in any of the first to third methods, the droplets of the recording liquid ejected from the nozzles are electrically controlled during the flight, and the droplets carrying the recording signal are selectively recorded. On the other hand, recording is performed by adhering the recording liquid onto a body. In the steam method, recording is performed by discharging a small droplet of a recording liquid from an ejection port in accordance with a recording signal. In other words, in the steam method, an electric recording signal is applied to a piezoelectric vibrating element attached to a recording head having a discharge port for discharging a recording liquid to change the mechanical vibration of the piezoelectric vibrating element. The recording liquid droplets are ejected from an ejection port and ejected to adhere to a recording medium.

[0008] Each of these four methods has its own features, but also has problems to be solved at the same time. First, in the first to third methods, the direct energy for generating a droplet of the recording liquid is electric energy, and the deflection control of the droplet is also by electric field control. Therefore, although the first method is simple in configuration, it requires a high voltage to generate small droplets, and it is difficult to form a multi-nozzle recording head, which is not suitable for high-speed recording. The second method is capable of multi-nozzle recording heads and is suitable for high-speed recording. However, the configuration is complicated and the electrical control of small droplets of recording liquid is advanced and difficult. Satellite dots tend to form on the top. Further, the third method makes it possible to perform printing with excellent gradation by atomizing small droplets of the recording liquid, but it is difficult to control the atomization state. In addition, there are drawbacks such as fogging of a recorded image and difficulty in using a multi-nozzle recording head, which is not suitable for high-speed recording.

On the other hand, the fourth system has relatively many advantages. First, the configuration is simple. In addition, since the recording liquid is ejected on demand from the ejection port of the nozzle to perform recording, of the droplets ejected and flying as in the first to third methods, small droplets not required for image recording are collected. No need to do. Further, unlike the first and second systems, there is no need to use a conductive recording liquid, and there is an advantage that the recording liquid has a high degree of freedom in terms of material. However, on the other hand, it is difficult to form a multi-nozzle recording head because there are problems in processing the recording head and it is extremely difficult to reduce the size of the piezo vibrating element having a desired resonance frequency. In addition, since the ejection of small droplets of the recording liquid is performed by the mechanical energy of mechanical vibration of the piezo-vibrating element, the above-mentioned difficulty in forming a multi-nozzle is unsuitable for high-speed recording. I have.

As described above, the conventional method has advantages and disadvantages in terms of configuration, high-speed recording, multi-nozzle recording head, generation of satellite dots, fogging of recorded images, and the like. It is limited that it can be applied only to the intended use.

However, such an inconvenience can be substantially eliminated by the ink jet recording system disclosed in Japanese Patent Publication No. 56-9429 proposed by the present applicant. In this method, ink in a liquid chamber is heated to generate air bubbles, which causes a pressure increase in the ink, and the ink is ejected from a fine capillary nozzle to perform recording. A similar recording method is disclosed in Japanese Patent Publication No. 61-59914. this is,
By heating a part of the liquid in the liquid path communicating with the discharge port for discharging the liquid in a predetermined direction to cause film boiling, a flying droplet of the liquid discharged from the discharge port is formed, The droplets are made to adhere to the recording medium to perform recording. Specifically, as shown in FIG. 1 and FIG. 2 of the publication, the recording liquid undergoes a sudden change in state at a heat acting portion provided in a nozzle-like liquid path portion, thereby causing the state to change. The recording liquid is ejected from the ejection port by the action force based on the change. According to the description in the publication, such an outlet has an inner diameter of 100 (μm),
By thermally melting a cylindrical glass fiber having a thickness of 10 (μm), a discharge port having a diameter of 60 (μm) is formed. In addition, there is also described a method in which a discharge port is formed separately from a liquid path, and then a hole is formed in, for example, a glass plate by electron beam processing, laser processing, or the like, and is combined with the liquid path. In any case, it is very difficult to form such a fine discharge port stably with high precision industrially. According to the publication, a recording head having another discharge port is disclosed in FIGS. 3, 4 and 5 of the publication. It describes that a groove plate formed with a groove having a width of 60 (μm), a depth of 60 (μm), and a pitch of 250 (μm) by a cutting machine is bonded to a substrate provided with an electric / thermal converter section. . However, also in this case, the discharge port to be formed is very fine, and when forming a groove with a fine cutting machine, chipping or cracking often occurs, resulting in a low yield. In addition, the formed discharge port cannot be formed with high accuracy at its end portion due to chipping or the like. Further, when the groove plate is bonded to the substrate after the formation of the groove, the adhesive clogs the discharge port, thereby lowering the yield.

Incidentally, a more specific method of manufacturing the recording head shown in FIGS. 3, 4 and 5 of the publication is disclosed in Japanese Patent Application Laid-Open No. 55-128471 and Japanese Patent Publication No. 59-43314. It is disclosed in the gazette. Japanese Patent Application Laid-Open No. 55-128471 has a recording liquid flow path composed of pores, and the recording liquid in the recording liquid flow path is formed into small droplets from an ejection port communicating with the pores. A recording head that ejects ink to fly and adheres onto the surface of a recording medium to record, and has a predetermined number of ejection ports arranged in parallel, and the same number of pores are arranged in parallel at substantially the same density as the arrangement density of the ejection ports. It was set up. Further, Japanese Patent Publication No. 59-43314 has a pore serving as a recording liquid flow path, an opening having a predetermined diameter d communicating with the pore, and a heat generating portion provided along the pore. In the droplet ejection recording apparatus described above, the heat generating portion is disposed such that the edge near the opening is located within a range of d to 50d from the opening position. Furthermore, it is described that the heat generating portion is formed of a planar heat generating element that is long in the longitudinal direction of the pores.

[0013] The manufacturing method of the recording head described in JP-A-55-128471 and JP-B-59-43314 can be summarized as a part having a narrow groove using photosensitive glass. And the component on which the heating resistor pattern is formed,
A discharge orifice is formed by bonding. That is, it differs from that described in Japanese Patent Publication No. 61-59914 in that narrow grooves are formed by etching the photosensitive glass, but the same is true in that the clogging of the discharge orifice by the adhesive occurs and the yield decreases. It is. This is because these recording heads have a problem in the fundamental configuration itself having an ejection port (orifice).

Further, according to JP-A-55-59974,
JP-B-61-59914, JP-A-55-128471, and JP-A-59-43314, a substrate having an ink flow channel as shown in Examples in JP-B-59-43314, a substrate having a heating element A manufacturing method of bonding with an adhesive capable of forming a three-dimensional network structure is described. However, as long as the basic configuration of forming the discharge orifice by bonding is the same as that described in the above three publications, there is a similar problem, that is, the problem that the discharge orifice is blocked by the adhesive.

On the other hand, according to Japanese Patent Publication No. 62-59672, a discharge method described in Japanese Patent Publication No. 61-59914, Japanese Patent Application Laid-Open No. 55-128471, and Japanese Patent Publication No. A process is disclosed that eliminates the disadvantages of the orifice process. That is, as in these publications, in the method of forming an ink flow path by grinding a glass plate, the method of forming an ink flow path by etching a photosensitive glass, and the like, the inner wall surface of the ink flow path is rough, and the inner surface is a droplet. Since a large resistance is required against a sudden change in pressure for ejection, a large amount of energy is required for ejecting droplets, which is contrary to energy saving, and the glass is chipped and cracked during grinding, resulting in a low yield. Bad
It is a major factor that impairs the stability and uniformity of droplet ejection,
In addition, the photosensitive glass has a limitation in fine processing accuracy and has a high material cost. In this regard, Japanese Patent Publication No. 62-59672 discloses that after a plurality of active elements such as a heating element and a piezoelectric element are fixedly provided at a predetermined position on a substrate as an energy source for applying energy for generating droplets to the ink. (Electrodes are appropriately formed), a photosensitive composition layer is formed at a predetermined thickness on the substrate surface by a coating method or the like, and an orifice portion, a working portion, an ink supply passage portion, an ink discharge passage is formed by a normal photolithography method. An ink flow path groove for forming an ink flow path of a part or the like is formed, and thereafter, an upper lid is joined to manufacture a recording head.

However, according to the head manufacturing method described in the publication, when the orifice is formed, that is, when the upper lid is joined to the active element side of the substrate in which the ink flow channel is formed, the above-described feature still remains. There are the same problems as in JP-B-61-59914, JP-A-55-128471, and JP-B-59-43314. That is, the orifice is clogged by the adhesive, and the yield of head manufacturing is significantly reduced. Suppose, in the method of Japanese Patent Publication No. 62-59672, without using an adhesive when joining the upper lid, utilizing the adhesiveness of the photosensitive composition layer before it is completely cured, heat bonding or thermocompression bonding Even in this case, in this case, the ink discharge path portion,
There is a problem that the orifice portion is deformed and a desired shape cannot be obtained. After all, even in the case of this publication, a problem due to the basic structure of having an orifice remains.

According to JP-A-59-118469,
A recording head having an orifice plate integrally including a plurality of orifices, a separating portion for separating the orifices, and an outer frame portion for an ink storage portion is shown. Although having a different purpose from the above, there is one disclosed in Japanese Patent Application Laid-Open No. 1-152068 as a device having a similar configuration. This is, as shown in FIG. 4 and the like in the publication, a substrate having a heating element (resistor) and an ink feed channel (separating section).
And an orifice (nozzle) plate. Further, those disclosed in JP-A-59-118469 and JP-A-1-52068 are suitable for manufacturing a nozzle plate, head and the like.
4 and JP-A-62-234941. Further, as one suitable for assembling the heads described in these four publications, there is one disclosed in JP-A-62-264957. This involves forming a polymer barrier layer on a substrate, arranging a nozzle plate on this barrier layer, and then applying heat and pressure to the nozzle plate with sufficient time and temperature for the barrier layer to plastically deform, Thereafter, a process of fixing the substrate, the barrier layer, and the nozzle plate is performed to manufacture an ink jet printer head.

However, Japanese Patent Application Laid-Open Nos. 59-118469, 1-152068, 59-207264, and
Japanese Patent Application Laid-Open Nos. 62-234941 and 62-264957 also have problems due to having an orifice (nozzle) plate. First, a fine orifice (nozzle,
It is technically quite difficult to form an orifice plate having a discharge port) with high precision. For example, even if the orifice plate is formed with high precision, the manufacturing cost is high and the head becomes expensive. Further, in the above-mentioned publications, as described in detail in JP-A-62-264957, a substrate having a heating element with an orifice plate and a photoresist barrier layer (dry film barrier layer, ink feed channel)
When bonding or bonding through, the photoresist barrier layer deforms, or the adhesive goes around unnecessary parts and clogs the ink feed channel, in the worst case,
It also clogs the fine orifices. This is also a problem caused by the fundamental configuration and manufacturing method of having an orifice plate and passing through a joining or bonding step.

There is another problem common to all of the above publications. That is, each of the above-described ink jet recording heads has a fine orifice (= nozzle or ejection port), and performs recording by ejecting or flying ink from such an orifice and attaching to a recording medium. Common. Here, the fine orifice is generally
Since the size is about 30 to 50 (μm) (the shape is not necessarily round but also square), impurities contained in the ink or dust generated from the ink supply system, supply path, etc. There is always a risk that the orifice holes will be clogged due to (for example, dust may be mixed in during the manufacture of the head-ink supply system or small pieces may fall off from the sliding parts).

Incidentally, JP-A-62-253456, JP-A-63-182152, JP-A-63-197653,
JP-272557, JP-A-63-272558, JP-A-63-281
There are also recording heads described in JP-A-853, JP-A-63-281854, JP-A-64-67351, JP-A-1-97654 and the like. Each of the publications described above has individual characteristics when individually examined, but as a basic configuration, a slit nozzle plate having a slit-shaped opening is used instead of a conventional orifice plate having an orifice. In common. However, also in these cases, the slit width is several tens (μ) as described in, for example, JP-A-62-253456.
m), which is very small, and there is no substantial difference from the orifice (nozzle) diameter of the conventional ink jet, and since it has a slit shape, it is a degree that has become slightly advantageous to clogging. The problem of clogging, which is a fatal drawback, remains unsolved. In addition, even though the slit method is used, since it is based on a manufacturing method of forming and joining a slit nozzle plate, the manufacturing method is completely different from that of forming and joining a conventional inkjet orifice plate as described above. However, there is no cost advantage in manufacturing a slit nozzle plate involving fine processing, and the process of assembly joining (adhesion) is not reduced, and there is no cost advantage. This is the same as in Japanese Patent Application Laid-Open No. 61-189950, which uses a slit nozzle plate, as in Japanese Patent Application Laid-Open No. 62-253456, and the problem of clogging remains.

Further, according to the above-mentioned Japanese Patent Application Laid-Open No. 62-253456, bubbles of ink vapor are formed, and when each bubble bursts, the action force generated by the preserving momentum of the bursting bubbles causes the ink layer to move from the ink layer. An ejection principle is described in which a droplet of ink is ejected toward a moving recording medium in a direction perpendicular to a heating element and an ink layer. Droplets of ink ejected according to such a principle are considered to be the same as liquid microjets whose existence is recognized in the field of research on the collapse of cavitation bubbles. this is,
A columnar jet is formed so as to penetrate the bubble when the bubble collapses, and this columnar jet (liquid microjet) is used for ink-jet, Japanese Patent Application Laid-Open Nos. 61-189949 and 64 No. -30758. What is described in the above-mentioned JP-A-61-189950,
It can be seen that the ejection principle disclosed in JP-A-61-189949 and JP-A-64-30758 is applied to a slit nozzle.

The method disclosed in Japanese Patent Application Laid-Open No. 61-189950 discharges ink droplets based on the principle of bursting bubbles. Although possible, there is an unavoidable disadvantage that the generation of ink mist due to the burst of bubbles significantly disturbs the image quality. In other words, the one described in the publication does not solve the problem of clogging as in the above-mentioned Japanese Patent Application Laid-Open No. 62-253456, and furthermore, the image quality is disturbed due to scattering of ink mist due to bursting of bubbles. Is also caused.

Furthermore, Japanese Patent Laid-Open Publication No. Sho 51 (1993) discloses an apparatus having no orifice or slit nozzle and eliminating the problem of clogging.
There are those disclosed in JP-A-132036 and JP-A-1-101157. However, when examining the ejection principle, it is difficult to say that the ejection principle can provide a satisfactory image quality. That is, the ejection principle of JP-A-51-132036 is the same as that described in JP-A-61-189950 described above, and has a disadvantage that the image quality is deteriorated due to bursting of bubbles.
The discharging principle in Japanese Patent Application Laid-Open No. 1-101157 is that the recording liquid is instantaneously boiled by energizing a minute heating element to fly in the form of a mist and perform recording. Recording is difficult, fogging and background smearing occur, and a good image cannot always be obtained.

Japanese Patent Application Laid-Open No. Sho 60-260, as an example, aims to improve the reliability and durability by preventing damage to the energy acting portion.
-208246 and JP-A-2-80253. In the ink jet printers disclosed in these publications, an opening or a notch is provided in the vicinity of the stop of the heating element layer to reduce a mechanical impact to prevent damage. However, this is intended only to prevent damage, and does not consider optimizing the ejection characteristics of ink droplets.

[0025]

As described above, in the conventional various ink jet systems, the problem of clogging of an orifice (nozzle) or a slit-shaped nozzle due to drying of dust and ink, which is a fatal disadvantage of the ink jet system, is described. There is. Further, there is a problem that a high-precision orifice (nozzle) cannot be formed on the head assembly. Further, there is a problem of assembly cost. Further, there is a problem that it is difficult to maintain and restore the reliability due to the presence of the orifice (nozzle). There is also a problem that the printing quality is low. That is, the conventional ink jet recording method has problems in reliability such as clogging, cost of the head, and image quality.

Here, an ink jet recording apparatus which solves the above-mentioned problems by eliminating the need for a nozzle plate or a slit-shaped nozzle has been filed by the present applicant as Japanese Patent Application No. 1-225777. In addition, the applicant filed Japanese Patent Application No. 1-3342.
In the ink flight recording apparatus filed as No. 32, a barrier is provided in the ink liquid surface to concentrate the pressure on the ink liquid surface with high efficiency, thereby improving the ink droplet flight characteristics. However, even in such an ink flying recording apparatus, the damage of the energy action section is a factor that hinders the durability of the device, and the heat generation distribution of the energy action section is made uniform to improve energy use efficiency and durability. It is desired.

[0027]

According to the first aspect of the present invention,
An ink level holding means for holding the ink supplied by the ink supply means; an energy action section for heating the ink held by the ink level holding means to generate bubbles that grow instantaneously; In an ink jet recording apparatus in which a signal input means for providing a drive signal according to image information is provided in an action section, an energy action section is formed of a heating element layer having a film thickness in a central portion thinner than a film thickness in a peripheral portion. .

According to a second aspect of the present invention, there is provided an ink level holding means for holding the ink supplied by the ink supply means, and the bubbles which grow instantaneously by heating the ink held by the ink level holding means. In an ink jet recording apparatus provided with an energy action section that causes the energy action section, and a signal input means for providing a drive signal according to image information to the energy action section, a ratio of the film thickness of a portion overlapping with a peripheral portion of the energy action section is reduced. As a result, a heat storage layer having a small thickness in a portion overlapping the central portion was formed.

[0029]

According to the first aspect of the present invention, the temperature distribution of the energy application section becomes uniform because the energy application section is formed of a thin film layer whose central portion is thinner than the peripheral portion. In addition, the thermal stress due to local high temperature is reduced, and the energy use efficiency is good, and the flying speed of the ink droplet is high.

According to a second aspect of the present invention, the heat storage layer is formed such that the thickness of the portion overlapping the central portion of the energy action portion is smaller than the thickness of the portion overlapping the peripheral portion. Is uniform, so that thermal stress due to local high temperature is relaxed, energy efficiency is good, and the flying speed of ink droplets is high.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink flying recording apparatus according to the present invention will be described with reference to the drawings. First, components of the recording head of the ink flying recording apparatus according to the present embodiment will be described with reference to FIGS. First, as illustrated in FIG. 2, the recording head 1 has a trapezoidally formed manifold 4 having a hollow ink supply chamber 3 connected to an ink supply pipe (ink supply means) 2. Is configured as A heating element substrate 6 having a slit 5 communicating with the ink supply chamber 3 is fixed to the top of the manifold 4. Comb-shaped barriers 7 are alternately formed on both sides of the slit 5 on the heating element substrate 6, and a flow path (ink liquid level holding means) 8 is formed between the barriers 7. These channels 8 are barriers 7
On the contrary, they are alternately comb-shaped and communicate with the slit 5. Further, on the heating element substrate 6, each of the flow paths 8 is located at the innermost side and a heater section (energy action section) is provided.
9 are formed. Therefore, when the planar arrangement of the heater portions 9 is viewed, as illustrated in FIG. 3, a staggered arrangement is provided on both sides of the slit. Also, the fluid resistance portion 10 having the same height as the barrier 7 is placed on the heating element substrate 6 in the middle of each flow path 8.
Are formed. Further, a thin film conductive lead (signal input means) 12 covering the periphery of the heating element substrate 6 and being pressed and fixed by a frame-shaped holding member 11 is provided on the manifold 4.

Here, an example of the structure near the heater section 9 is illustrated in FIG. The heater section 9 has a heat storage layer 13 formed on the heating element substrate 6, and a heating element layer 14 formed thereon along with the control electrode 15 and the ground electrode 16. Further, in order to avoid direct contact with the ink. The surface is covered with a protective layer 17 and an electrode protective layer 18. Each heating element layer 14 is electrically connected to the thin-film conductive lead 12 via the control electrode 15 and the ground electrode 16 by wire bonding (not shown). The thin-film conductive leads 12 are connected to image information signal input means (not shown). In the recording head 1, as shown in the figure, the thickness of the heat storage layer 13 at the central portion is formed smaller than that at the peripheral portion.

First, the outline of the ink flying principle will be described.
First, the ink 19 (see FIG. 5) supplied from the ink supply pipe 2 to the ink supply chamber 3 passes through the fine slits 5 by capillary action and fills the entire area of the comb-shaped flow path 8 surrounded by the barrier 7. Will be. Note that, depending on the dimensions of the slit 5 and the flow path 8, it is not possible to sufficiently supply and hold the ink 19 over the entire flow path 8 by only the capillary phenomenon. By adjusting the height between a certain ink tank (not shown) and the recording head 1, the head difference may be used. In the steady state in which the height of the ink liquid level is adjusted so that the ink 19 is filled in the entire area of the flow path 8 and the respective heater sections 9 are also covered with the ink 19, each of the heaters 9 corresponds to the image information. Heating element layer 14
When an electric current is individually applied to the heating elements, bubbles are generated in the ink liquid on the heating element layer 14 that has generated heat. The ink 19 flies in a direction substantially perpendicular to the surface of the heater 9 (substrate surface) due to the propulsive force of the bubbles.

Further, the ink flying principle will be described in detail with reference to FIG. In FIG. 5, the heater 9 and its peripheral portion are shown in an enlarged manner, but electrodes and the like are omitted for simplicity. FIG. 5 (a) shows a steady state, in which ink 1
9 is filled, and the heater 9 is also covered with the ink 19. When the heater section 9 is heated, the surface temperature of the heater section 9 rises rapidly, and the ink layer is heated until a boiling phenomenon occurs in the adjacent ink layer, so that fine bubbles 20 are scattered as shown in FIG. . At this time, for example, when the thickness of the heat storage layer 13 of the heater section 9 is uniform as in the conventional apparatus, the temperature distribution is high in the central portion and low in the peripheral portion. To the peripheral portion. However, in the recording head 1 of the present embodiment, FIG.
Since the heat storage layer 13 is formed to be thin at the center and thick at the periphery as shown in FIG. Air bubbles 20 will be generated inside.

Then, the adjacent ink layer heated rapidly on the entire surface of the heater section 9 is instantaneously vaporized, and
A boiling film is formed as shown in FIG. In the state in which the bubbles 20 grow in this way, the surface temperature becomes 300 to 350 ° C.,
It is in a so-called film boiling state. In addition, the ink 19 layer above the heater section 9 is in a state where the ink liquid level is raised as shown in the figure by the driving force of bubble growth. At this time, since the boiling phenomenon occurs uniformly on the upper surface of the heater section 9, the boundary surface between the bubble 20 and the ink 19 formed also becomes flat,
Since the pressure acts on the ink 19 more efficiently than a spherical bubble generated when the thickness of the heat storage layer 13 is uniform, a larger ink column 21 is formed.

FIG. 4D shows a state in which the bubble 20 has grown to the maximum, and a state in which the ink column 21 has further grown from the ink liquid level. The time required to reach such maximum bubbles depends on the structure of the head (heating element substrate 6), applied pulse conditions, etc., but is usually 5 to 30 (μsec) after pulse application.
It takes about. At the point in time when the bubble reaches the maximum, the heater 9 has not been energized, and the surface temperature of the heater 9 is decreasing. The timing when the bubble 20 is maximized is slightly delayed from the timing of applying the electric pulse. FIG. 3E shows a state in which the bubble 20 is cooled by the ink 19 or the like and starts to contract. The front end of the ink column 21 moves forward while maintaining the extruded speed, and the rear end of the ink column 21 flows back along with the contraction of the bubble 20, causing the ink 19 to flow back to the ink liquid surface. Constriction occurs. When the bubble 20 further contracts, the ink 19 comes into contact with the surface of the heater 9 as shown in FIG.
The surface becomes more rapidly cooled. Then, the ink column 21 is cut from the ink liquid surface, and flies at a speed of 2 to 12 (m / s) in the direction of the recording medium (not shown). The flying speed at this time depends on the structure of the head (heating element substrate 6), the physical properties of the ink, the conditions of the applied pulse, and the like. If the flying speed is relatively low (2 to 3 (m / s)), the ink 19 The ink 19 flies in the form of drops, and when relatively fast (7 to 12 (m / s)), the ink 19 flies in the form of an elongated column. Thereafter, as shown in FIG. 7G, the state returns to the steady state similar to FIG. 7A, and the ink 19 is filled in the entire area of the flow path 8 and the bubbles 20 are completely eliminated.

Next, the structure and manufacturing method of the heating element substrate 6 will be described in detail. In this embodiment, the heating element substrate 6 is one of important parts. First, the heating element substrate 6 itself is made of a material such as glass, alumina (Al ₂ O ₃ ), or silicon. The slit 5 is preferably formed by a laser beam processing method in that it has relatively high precision and can be processed at low cost. However, when single crystal silicon is used as the substrate, the slits 5 can be formed with very high precision even by anisotropic etching.

Heat storage layer 13 formed on heating element substrate 6
Is formed of, for example, a SiO ₂ layer, and is formed by a thin film forming method such as a sputtering method in the case of a glass or alumina substrate, and is formed by a thermal oxidation method in the case of a silicon substrate. As the thickness of the heat storage layer 13, the heating element layer 1
4 is about 1 to 5 (μm) in a thick portion overlapping the peripheral portion, and 0.5 in a thin portion overlapping the central portion of the heating element layer 14.
It is good to be about 4 (μm). It should be noted that the production of the heat storage layer 13 that is partially thin in this manner can be performed by well-known photolithography and etching techniques. For example, when the heat storage layer 13 is made of SiO ₂ , an opening is formed by photolithography using a photoresist OFPR800 manufactured by Tokyo Ohka, and etching is performed with a buffer etching solution of hydrofluoric acid and ammonium fluoride, thereby reducing the number of layers. The heat storage layer 13 having a thickness of 0.5 to 1.0 (μm) can be partially obtained in minutes.

Further, the material constituting the heating element layer 14 is, for example, a mixture of tantalum-SiO ₂ , tantalum nitride, nichrome, silver-palladium alloy, silicon semiconductor,
Alternatively, boride of a metal such as hafnium, lanthanum, zirconium, titanium, tantalum, tungsten, molybdenum, niobium, chromium, and vanadium can be used.
Of these, metal borides are particularly preferred, and among them, hafnium boride is the most characteristically preferred.
Zirconium boride, lanthanum boride, tantalum boride, vanadium boride, and niobium boride are preferred in that order. The heating element layer 14 is formed using such a material by an electron beam method, an evaporation method, a sputtering method, or the like. The area of the film thickness, so that the calorific value per unit time is a desired value,
It is appropriately set according to the material, the shape and size of the heat acting portion, the actual power consumption, etc., but usually 0.001 to 5 (μm)
, Preferably about 0.01 to 1 (μm).

The materials of the control electrode 15 and the ground electrode 16 may be the same as ordinary electrode materials.
1, Ag, Au, Pt, Cu and the like are used. These are formed at a predetermined position in a predetermined size, shape, and film thickness by an evaporation method or the like.

The protective layer 17 is for protecting the heat generating layer 14 without preventing the heat generated in the heat generating layer 14 from being effectively transmitted to the ink 19 side.
Silicon oxide (SiO ₂ ), silicon nitride, magnesium oxide, aluminum oxide, tantalum oxide, zirconium oxide, or the like is used. The production method is based on an electron beam method, an evaporation method, a sputtering method, or the like. And the film thickness is usually 0.
01 to 10 (μm) is preferable, and 0.1 to 5 (μm) (among others, 0.1 to 3
(μm) is optimal). The protective layer 17 is formed in a single-layer or multiple-layer structure using these materials. In addition to these layers, the protective layer 17 protects the heater section 9 from cavitation generated when the bubbles 20 contract and disappear. It is desirable to form a metal layer such as Ta on the surface. Specifically, T
A metal layer such as a may be formed with a thickness of about 0.05 to 1 (μm).

As a material of the electrode protection layer 18, for example, polyimide isoindoloquinazolinedione (trade name: PI
Q, manufactured by Hitachi Chemical Co., Ltd.), polyimide resin (trade name: PYRA)
LIN, manufactured by DuPont), cyclized polybutadiene (trade name:
JSR-CBR, manufactured by Japan Synthetic Rubber Co., Ltd., Photo Nice (trade name: manufactured by Toray Industries, Inc.), and other photosensitive polyimide resins are used.

Next, the durability of the heater section 9 will be described. First, in the recording head 1 of this embodiment, the heating element layer 1
By forming the film thickness d of the heat storage layer 13 overlapping with the central part of the heater 4 thin, the temperature distribution of the heater unit 9 becomes uniform and the durability is improved. That is, as in the conventional apparatus, the heat storage layer 1
In the case where the film thickness of the heater 3 is uniform, the central portion of the heater section 9 is locally heated to generate an excessive thermal stress.
The cavitation shock at the time of the disappearance was added, causing destruction. However, in the recording head 1 of the present embodiment, since the temperature distribution of the heater section 9 is made uniform by partially reducing the thickness of the heat storage layer 13, thermal stress due to local high temperature is reduced. Durability is improved.

Incidentally, in the recording head 1 of this embodiment, FIG.
As illustrated in (a), the heat storage layer 13 in which the film thickness d is partially reduced is illustrated as the invention of claim 2.
The present invention is not limited to the above structure,
As an example, it is also possible to form the heating element layer 14 whose central portion has a smaller thickness than the peripheral portion thickness d '. Also in this case, as in the case where the thickness of the heat storage layer 13 is partially reduced, the temperature distribution of the heater section 9 becomes uniform, the boundary surface between the bubbles 20 and the ink 19 becomes flat, and the energy use efficiency and durability are improved. Performance will be improved.

Next, the results of an ejection experiment along with various conditions when the present applicant actually manufactures the recording head 1 and performs printing and recording will be described below. a. Specific Example 1 Condition Size of Heating Element Layer 14: 80 μm × 80 μm Thickness d ′ of Heating Element Layer 14: 0.5 μm Resistance Value of Heating Element Layer 14: 31 Ω Material of Heating Element Layer 14: Ta ₂ N Film of Heat Storage Layer 13 Thickness d Central part of the heater part 9: 1.0 μm Peripheral part of the heater part 9: 1.5 μm Material of the heat storage layer 13: SiO ₂ drive voltage: 15 V Pulse width: 5.0 μsec Continuous drive frequency: 2.0 kHz (for solid printing) Ink: BJ130 ink manufactured by Canon Inc. Recording medium: NM matte coated paper manufactured by Mitsubishi Paper Mills Spacing with the recording medium: 1.0 mm This is a central part of the heater unit 9 by photolithography of OFPR800 (Tokyo Ohka). An opening was formed in a portion where is formed, and SiO ₂ was etched by 0.5 (μm) with a buffer etching solution of hydrofluoric acid and ammonium fluoride to reduce the thickness d. b. Specific Example 2 Conditions Thickness d ′ of Heating Element Layer 14 Center part of heater part 9: 0.3 μm Peripheral part of heater part 9: 0.5 μm Material of heating element layer 14: Ta ₂ N An opening was formed at the center of the heater section 9 by photolithography of OFPR800 (manufactured by Tokyo Ohka), and Ta ₂ N was etched by 0.2 (μm) by dry etching to reduce the thickness d ′. c. Comparative Example 1 Conditions Thickness d 'of heating element layer 14: 0.5 μm Thickness d of heat storage layer 13: 1.5 μm Others are the same as in Example 1.

When a printing and recording experiment was performed under the above conditions, in Comparative Example 1, the flying speed of the ink 19 was about 5.5 (m / s).
The image flowed in the head scan direction, albeit slightly, and the endurance time for continuous driving was confirmed to be about 22 hours. However, in the specific example 1, the flying speed of the ink 19 is 8.
At 5 (m / s), the image was high quality without flowing, and the endurance time for continuous driving was about 475 hours. Further, in the specific example 2, the flying speed of the ink 19 is 9.2 (m / s), the image is extremely high quality, and the durability time for continuous driving is about 420.
It was time.

As is clear from the above experimental results,
By forming the thickness d of the heat storage layer 13 overlapping the central portion of the heating element layer 14 to be small, or by forming the heating element layer 14 having a central portion thinner than the peripheral portion. A recording head 1 with high performance and good durability can be obtained. In addition,
It is also possible to provide such two conditions in one recording head 1.

[0048]

According to the first aspect of the present invention, an ink level holding means for holding the ink supplied by the ink supply means is provided, and the ink held by the ink level holding means is heated to grow instantaneously. In an ink jet recording apparatus provided with an energy action section that generates bubbles that generate bubbles and signal input means for providing a drive signal according to image information to the energy action section, the energy action section is compared with the thickness of the peripheral portion. By forming a heating element layer with a thin film at the center,
The uniformity of the temperature distribution in the energy application section reduces the thermal stress due to local high temperature and improves durability.Moreover, the energy use efficiency is good and the ink droplet flying speed is high, so the printing quality is also good. It has effects such as good.

According to a second aspect of the present invention, there is provided an ink liquid level holding means for holding the ink supplied by the ink supply means, and bubbles which grow instantaneously by heating the ink held by the ink liquid level holding means are provided. In an ink jet recording apparatus provided with an energy action section that causes the energy action section, and a signal input means for providing a drive signal according to image information to the energy action section, a ratio of the film thickness of a portion overlapping with a peripheral portion of the energy action section is reduced. By forming a heat storage layer with a thin film thickness at the part overlapping the central part, the temperature distribution of the energy acting part becomes uniform, so the thermal stress due to local high temperature is relaxed and the durability is improved, In addition, since the energy use efficiency is good and the flying speed of the ink droplets is high, the print quality is good.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of a main part showing an embodiment of the present invention.

FIG. 2 is an overall exploded perspective view.

FIG. 3 is a plan view of a main part.

FIG. 4 is a longitudinal sectional front view of a main part.

FIG. 5 is an operation explanatory diagram.

[Description of Signs] 1 Ink flying recording device 8 Ink liquid level holding means 9 Energy application section 12 Signal input means 13 Heat storage layer 14 Heating element layer

Continued on the front page (72) Inventor Takayuki Yamaguchi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Shuji Motomura 1-3-6 Nakamagome, Ota-ku, Tokyo Co., Ltd. Ricoh (72) Inventor Eiko Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (56) References JP-A-55-132258 (JP, A) JP-A-63-189243 (JP) , A) JP-A-63-42872 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/05 B41J 2/16

Claims (2)

(57) [Claims] An energy action section for providing ink level holding means for holding ink supplied by an ink supply means, and heating the ink held by the ink level holding means to generate bubbles that grow instantaneously. In the ink jet recording apparatus provided with signal input means for providing a drive signal according to image information to the energy action section, the thickness of the energy action section is smaller at the central portion than at the peripheral portion. An ink flying recording device formed of a heating element layer. 2. An energy action section for providing ink level holding means for holding ink supplied by the ink supply means, and heating the ink held by the ink level holding means to generate bubbles that grow instantaneously. In the ink jet recording apparatus provided with a signal input means for providing a drive signal according to the image information to the energy application section, the central portion compared to the film thickness of the portion overlapping the peripheral portion of the energy application section An ink jet recording apparatus, wherein a heat storage layer having a small film thickness in an overlapping portion is formed.