JP2849399B2 - Liquid jet recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid jet recording apparatus, and more particularly, to a liquid jet recording apparatus.
It relates to an ink jet printer.

2. Description of the Related Art Non-impact recording methods have recently attracted attention in that the generation of noise during recording is extremely small to a negligible level. Among them, the so-called ink jet recording method, which can perform high-speed recording and can perform recording on so-called plain paper without requiring a special fixing process, is an extremely powerful recording method. Some have been proposed and commercialized with improvements, while others are still being put to practical use.

In such an ink jet recording method, recording is performed by flying droplets of a recording liquid called so-called ink and attaching the droplets to a recording member. The control method for controlling the flying direction of the generated recording liquid droplet is roughly classified into several types.

First, the first method is disclosed in, for example, US Pat. No. 3,060,429 (Tele type method),
Recording liquid droplets are generated by electrostatic attraction, and the generated recording liquid droplets are subjected to electric field control according to a recording signal, and recording is performed by selectively adhering the recording liquid droplets onto a recording member. It is.

More specifically, in more detail, an electric field is applied between the nozzle and the accelerating electrode to discharge a uniformly charged droplet of the recording liquid from the nozzle, and the discharged droplet of the recording liquid is converted into a recording signal. In accordance with this, recording is performed by causing the droplets to fly between the xy deflection electrodes configured so as to be electrically controllable and selectively adhering small droplets onto the recording member by a change in the intensity of the electric field.

The second method is described, for example, in US Pat. No. 3,596,275,
The method disclosed in US Pat. No. 3,298,030 and the like (S
Weet method) in which droplets of the recording liquid with a controlled charge amount are generated by a continuous vibration generation method, and the generated droplets with a controlled charge amount are subjected to a uniform electric field. The recording is performed on the recording member by flying between the deflection electrodes.

More specifically, a charging electrode configured so that a recording signal is applied in front of an orifice (ejection port) of a nozzle, which is a part of a recording head provided with a piezoelectric vibrating element, is separated by a predetermined distance. The piezoelectric vibrating element is mechanically vibrated by applying an electric signal of a constant frequency to the piezoelectric vibrating element, and a droplet of the recording liquid is discharged from the discharge port. At this time, a charge is electrostatically induced in the recording liquid droplet discharged by the charging electrode, and the droplet is charged with a charge amount according to the recording signal. When the droplet of the recording liquid whose charge amount is controlled flies between the deflection electrodes to which a constant electric field is uniformly applied, the droplet is deflected according to the added charge amount and carries a recording signal. Only the recording material can be deposited on the recording member.

The third method is a method (Hertz method) disclosed in, for example, US Pat. No. 3,416,153, in which an electric field is applied between a nozzle and a ring-shaped charging electrode, and a continuous vibration generation method is used. This is a method in which small droplets are generated and atomized for recording. That is, in this method, the atomization state of the small droplet is controlled by modulating the electric field intensity applied between the nozzle and the charging electrode in accordance with the recording signal, and the image is recorded with the gradation of the recorded image.

The fourth system is, for example, a system (Stemme system) disclosed in US Pat. No. 3,747,120, and this system is fundamentally different from the above three systems in principle.

That is, in each of the three methods, the droplet of the recording liquid discharged from the nozzle is electrically controlled during the flight, and the droplet carrying the recording signal is selectively attached to the recording member. On the other hand, according to the Stemme method, recording is performed by ejecting a small droplet of recording liquid from an ejection port in accordance with a recording signal.

That is, in the Stemme method, the piezoelectric vibrating element attached to the recording head having the ejection port for ejecting the recording liquid includes:
Applying an electrical recording signal, converting the electrical recording signal into mechanical vibration of a piezo-vibrating element, and ejecting a droplet of the recording liquid from the ejection port in accordance with the mechanical vibration to cause the droplet to fly and adhere to the recording member. Is to record.

Each of these four conventional methods has its own features, but on the other hand, there are points that can be solved.

That is, in the first to third methods, the direct energy of the generation of the droplet of the recording liquid is electric energy,
Droplet deflection control is also electric field control. Therefore, the first method is simple in structure, but requires a high voltage to generate small droplets, and is not suitable for high-speed printing because it is difficult to use a multi-nozzle recording head.

The second method enables multi-nozzle recording heads and is suitable for high-speed recording. However, the method is complicated in structure, and the electrical control of small droplets of recording liquid is difficult and difficult. Are liable to occur.

The third method has a feature that an image having excellent gradation can be recorded by atomizing a recording liquid droplet, but on the other hand, it is difficult to control the atomization state, and fogging occurs in the recorded image. In addition, there are problems such as the fact that it is difficult to use a multi-nozzle recording head, and it is not suitable for high-speed recording.

The fourth scheme has relatively many advantages over the first to third schemes. That is, in order to perform recording by discharging the recording liquid from the discharge port of the nozzle on demand (on-demand), it is simple in terms of the configuration. It is not necessary to collect small droplets that are not required for recording an image, and there is no need to use a conductive recording liquid as in the first and second methods, and the recording liquid material Has a great advantage such as a large degree of freedom. 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 piezoelectric vibrating element having a desired resonance number. However, since the recording liquid droplets are ejected and fly by the mechanical energy of mechanical vibration of the piezo-vibration element, it is not suitable for high-speed recording.

Further, Japanese Patent Application Laid-Open No. 48-9622 (the aforementioned U.S. Pat.
No. 120) describes, as a modification, the use of thermal energy instead of the mechanical vibration energy by means such as the piezo-vibration element.

That is, the above-mentioned publication describes a so-called bubble jet liquid jet recording apparatus which uses a heating coil for directly heating a liquid as a pressure increasing means instead of a piezo vibrating element in order to generate vapor which causes a pressure increase. I have.

However, the above publication discloses that a heating coil serving as a pressure increasing means is energized to directly evaporate the liquid ink in a bag-shaped ink chamber (liquid chamber) having only one opening through which the liquid ink can enter and exit. However, there is no suggestion as to how to perform the heating when the liquid is continuously and repeatedly discharged. In addition, since the position where the heating coil is provided is provided at the deepest part of the bag-shaped liquid chamber far from the supply path of the liquid ink, in addition to being complicated in terms of the head structure, continuous It is not suitable for repeated use.

Moreover, according to the technical contents described in the above-mentioned publication, it is not possible to quickly form a preparation state for the next liquid discharge after performing the liquid discharge with the generated heat which is practically important.

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 and occurrence of fogging of a recorded image, etc. There was a restriction that only the application was possible.

The bubble jet recording method described above is an excellent recording method that can easily realize high density and high integration.However, in order to aim at more detailed image quality of copiers and the like, a heat generating portion, in other words, a nozzle It is necessary to arrange the array at an ultra high density of 16 lines / mm or more. In addition, in the case of ultra-high density, the pixel diameter naturally becomes small, and the number of dots to be printed on the paper surface inevitably increases, so that it takes a lot of time to form one image from a simple viewpoint. . Therefore, it is necessary to form ink droplets at a high frequency exceeding 4 KHz. That is, it is necessary to drive the heating element at a high frequency exceeding 4 KHz. In addition, it is necessary to form a multi-array of heating elements to form an image at high speed. In particular, when used for a copier or the like, a highly integrated head exceeding 256 nozzles is practically required, and a so-called full-line type head is optimally desirable. However,
There are still problems to be solved in order to realize such ultra-high density of 16 lines / mm or more, high integration exceeding 256 nozzles, and high frequency driving exceeding 4 KHz. In particular,
The so-called heat dissipation has been a major problem because heat generated from the heating element is quickly released without being accumulated.

Conventionally, the structure of the heating element substrate in the bubble jet recording method is as follows: a heat storage layer, an electrothermal conversion element (heating element), as shown in Japanese Patent Publication No. 61-59913, on a ceramic, glass, or silicon substrate. The electrode and the protective layer were laminated. In particular, silicon is suitably used as the substrate because of its excellent heat dissipation. However, for example, in the case of an A4 Full Line type multi-array head, the silicon substrate requires a substrate length of at least 210 mm, and it is extremely difficult to obtain a silicon substrate of this length at present. Therefore, conventionally, when a line type head is used, as shown in Japanese Patent Application Laid-Open No. 55-132253, a method is used in which the head is divided into blocks and the blocks are arranged in a staggered manner on the same support plate. Have been. However, in this method, there is a disadvantage that positioning of each block requires precision and that the ejection characteristics vary depending on the block. In particular, in the case of an ultra-high-density array of 16 lines / mm or more, even a slight error in the alignment between blocks greatly affects the dot position accuracy on the recording surface.
Extremely high-precision alignment was required, which caused the yield to deteriorate.

In the case of a glass substrate, an alumina substrate used in a thermal head, etc., from the viewpoint of thermal conductivity, an ultra-high density,
In the case of high integration and high frequency driving, heat radiation is not enough, head temperature rises, satellite dots are generated, frequency response is poor, and image quality is significantly reduced, causing problems. Was.

Also, as shown in Japanese Patent Application Laid-Open No. 62-231761, using a SiC ceramic substrate is extremely expensive compared to alumina, and when using a Full Line type, an extremely expensive head is required. There was a drawback that it would be.

Japanese Patent Application Laid-Open No. 64-1553 discloses that Al is used as a substrate.
_A head using AlN in addition to ₂ O ₃ and SiC is disclosed.
However, the production amount of AlN is small, there is concern about stable supply, and it is expensive. Furthermore, since the AlN active surface reacts with water and decomposes, when used as a heating element substrate, it becomes a problem in production or use, and the production process becomes complicated, the management is strict, or
The necessity of protection by a protective film or the like arises.

Further, JP-A-61-100464 discloses that the thermal conductivity is 2 W / cm.
An example using a substrate material of at least ℃ is disclosed.In the specification, in addition to the SiC as a material satisfying the above conditions, aluminum and a metal of copper are listed. Therefore, it is necessary to pay sufficient attention to the insulation between the electrodes. That is, a sufficiently dense and thick insulating layer is required between the electrode layer and the substrate. Aluminum and copper have a very large expansion coefficient, and the thermal expansion due to the driving of the heating element cannot be ignored when the density is 16 lines / mm or more.

As described above, none of the conventional substrate configurations has been satisfactory.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described drawbacks, and has as its main object to provide a heating element substrate having a completely different structure from the prior art and having excellent heat dissipation.

Another object is to improve the ink droplet ejection performance of an ultra-high-density array multi-nozzle head of 16 lines / mm or more.

Yet another purpose is to dispense at higher speeds (eg, 4K
(Above Hz) To improve the ink droplet ejection performance of the multi-nozzle head.

Still another object is to provide an inexpensive full line type head.

Configuration In order to achieve the above object, the present invention provides (1) a discharge orifice for discharging a recording liquid as liquid droplets, a liquid path communicating with the discharge orifice, and a method for applying heat to the recording liquid in the liquid path. A thermal energy generator for applying energy, wherein the thermal energy generator is provided on a lower layer laminated on a substrate. 16 energy generators / m
m is a full line type recording device arranged at an array density of at least m, wherein one thermal energy generator is driven at a driving frequency of 4 kHz or more, and the lower layer is constituted by at least a heat storage layer and a heat transfer layer The heat transfer layer has a thickness of 0.1 to 100 on a substrate by forming a thin film by sputtering or CVD.
or (2) a discharge orifice for discharging the recording liquid as liquid droplets, a liquid path communicating with the discharge orifice, and heat applied to the recording liquid in the liquid path. A heat energy generator for applying energy, wherein the heat energy generator is provided on a lower layer laminated on a substrate, and the lower layer is constituted by at least a heat storage layer and a heat transfer layer. In the liquid jet recording apparatus, the liquid jet recording apparatus includes the heat energy generator.
A full-line type recording device arranged at an array density of 16 lines / mm or more, wherein one heat energy generator is driven at a driving frequency of 4 kHz or more, and the heat transfer layer is formed by sputtering or CVD to form a thin film. 0.1-100μm on substrate
And a portion which is not provided between at least the adjacent heat energy generators.

 Hereinafter, a description will be given based on examples of the present invention.

First, based on FIG. 2, the principle of ink ejection by a bubble jet that suitably implements the present invention will be described.

(A) is a steady state, and the surface tension of the ink 2 and the external pressure are in an equilibrium state at the orifice surface.

FIG. 3B shows a state in which the heater 3 is heated until the surface temperature of the heater 3 rises rapidly and a boiling phenomenon occurs in the adjacent ink layer, and minute bubbles 4 are scattered.

(C) is a state in which the adjacent ink layer rapidly heated on the entire surface of the heater 3 is instantaneously vaporized to form a boiling film, and the bubbles 4 grow. At this time, the pressure in the nozzle rises by an amount corresponding to the growth of the bubble, the balance with the external pressure on the orifice surface is lost, and the ink column starts to grow from the orifice.

(D) is a state in which the bubble has grown to the maximum, and the ink 2 corresponding to the volume of the bubble is pushed out from the orifice surface. At this time, no current is flowing through the heater 3 and the surface temperature of the heater 3 is decreasing. The maximum value of the volume of the bubble 4 is slightly delayed from the timing of applying the electric pulse.

(E) shows a state where the bubble 4 is cooled by ink or the like and starts to contract. At the front end of the ink column, the ink moves forward while maintaining the pushed speed, and at the rear end, the ink flows backward from the orifice surface into the nozzle due to a decrease in the nozzle internal pressure due to the contraction of the bubble, and the ink column is constricted. .

4F, the bubble 4 is further contracted, the ink comes into contact with the heater surface, and the heater surface is cooled more rapidly. At the orifice surface, the external pressure is higher than the internal pressure of the nozzle, so that the meniscus largely enters the nozzle.
The tip of the ink column turns into a droplet and moves in the direction of the recording paper 5 to 10 m /
Flying at the speed of sec.

In (g), in the process in which the ink is supplied (refilled) to the orifice again by capillary action and returns to the state of (a), the bubbles have completely disappeared. 8 is a flying ink droplet.

FIG. 3 is an overall perspective view of a bubble jet recording head based on the above-described ejection principle. In the figure, 9 is a heating element substrate, 10 is a lid substrate, 11 is an ink supply port, and 12 is an orifice.

FIG. 1 is a view for explaining an embodiment of a liquid jet recording apparatus according to the present invention, and is a view for explaining a structure of a bubble generating means using a heating resistor, and FIG. FIG. 1B is a partial front view of the head as viewed from the orifice side, and is a partial cutaway view taken along a portion indicated by a chain line XX in FIG. 1A. In the figure, 13 is a substrate, 14
Is a lid substrate, 15 is an orifice, 16 is a liquid discharge section, 17 is a heat acting section, 18 is a heat generating section, 19 is a heat acting surface, 20 is a lower layer, 21 is a heating resistance layer, 22 is a protective layer, 23, Reference numeral 24 denotes an electrode, reference numeral 25 denotes a flow path wall, a predetermined number of grooves having a predetermined width and a predetermined depth are provided at a predetermined density on the surface of the substrate 13 provided with the heat generating portion 18 so as to be covered with the lid substrate 14. By joining, the orifice 15 and the liquid discharge section 16
Is formed.

The liquid discharge unit 16 has an orifice for discharging liquid droplets at its end, and thermal energy generated by the heat generation unit 18 acts on the liquid to generate bubbles, and a sudden state change due to expansion and contraction of the volume. Has a heat acting portion 17 which is a place for causing

The heat acting section 17 is located above the heat generating section 18 and
The heat acting surface 19 in contact with the liquid 18 is the bottom surface.

The heat generating portion 18 includes a lower layer 20 provided on the substrate 13, a heating resistor layer 21 provided on the lower layer 20, and the heating resistor layer 21 for generating heat. Electrodes 23 and 24 for supplying power to the power supply are provided on the surface thereof. The electrode 23 is
The electrode is common to the heat generating part of each liquid discharge part, and the electrode 24 is
It is a selection electrode for selectively causing the heat generating section of each liquid discharge section to generate heat, and is provided along the flow path of the liquid discharge section.

Examples of the material of the substrate 13 include glass, ceramics, metal, and silicon.In the case of a multi-nozzle type head, and further in the case of a full line type head, glass or alumina is used for a large-area substrate. This is preferable in that it can be obtained at low cost.

The lower layer 20 includes a heat transfer layer 20-1 and a heat storage layer 20-2 provided thereon. The heat transfer layer is a layer provided below the heat storage layer and intended to quickly release the heat generated from the heat generating portion from the heat generating portion. Therefore, the heat transfer layer
It is formed of a material having higher thermal conductivity than the substrate and the heat storage layer. That is, the thermal conductivity of glass is about 0.017 J / s · cm · ° C., and the thermal conductivity of alumina is greater than 0.32 J / s · cm · ° C. That is, it is formed of a material having a thermal conductivity higher than 0.32 J / s · cm · ° C. The material of the heat transfer layer is a material that satisfies the above conditions and has a softening point and a melting point of 300 ° C. or more, taking into consideration that the temperature of the heat generating portion rises to around 300 ° C. For example, copper, aluminum, nickel, platinum,
Simple substances such as gold, silver, zinc, iron, tungsten, magnesium, silicon, calcium, cobalt, molybdenum, chromium, niobium, beryllium, iridium, and palladium, and alloys and mixtures thereof, as well as SiC, BeO, and Al
N, cubic BN, diamond-like carbon and the like. Using these materials, usually 0.05μm or more on the substrate by a known thin film forming method such as sputtering or CVD, preferably,
It is laminated to a thickness of 0.1 to 100 μm. On top of this heat transfer layer,
As the heat storage layer, a SiO ₂ thin film is formed by using a vacuum thin film forming method such as sputtering or CVD. The heat storage layer can form a thin film having a desired thickness with good film formability by using a vacuum thin film forming method, and can also control the composition thereof, and the film thickness is usually 0.1 to 50 μm, preferably, 1 to 10 μm
Formed.

As the material constituting the heating resistor layer 21, the useful, 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, tungsten, molybdenum, niobium, chromium, and vanadium can be used.

Among these materials constituting the heat generating resistance layer 21, metal borides can be cited as being particularly excellent. Among them, hafnium boride has excellent characteristics, followed by zirconium boride and boron boride. Lanthanum boride, tantalum boride,
The order is vanadium boride and niobium boride.

The heat generating resistance layer 21 can be formed using the above-mentioned materials by a method such as photolithography, electron beam evaporation, sputtering, CVD, or plasma CVD. The thickness of the heat generating resistance layer 21 is determined according to the area, the material, the shape and size of the heat acting portion, the actual power consumption, and the like so that the amount of heat generated per unit time is as desired. Although it is usually, it is 0.001 to 5 μm, preferably 0.01 to 1 μm.

As the material constituting the electrodes 23 and 24, many commonly used electrode materials are effectively used.Specifically, for example, metals such as Al, Ag, Au, Pt, Cu, and the like, Alloys and the like are used, and they are provided at predetermined positions in a predetermined size, shape, and thickness by a technique such as vapor deposition or sputtering.

The characteristics required for the protective layer 22, without preventing the heat generated in the heating resistance layer 21 from being effectively transmitted to the recording liquid,
This means that the heating resistance layer 21 is protected from the impact force when the recording liquid or bubbles disappear. Useful materials for forming the protective layer 22 include, for example, silicon oxide, magnesium oxide, aluminum oxide, tantalum oxide, zirconium oxide, and the like.These include electron beam evaporation and sputtering, CVD, plasma CVD, It can be formed using a thin film forming technique such as a vapor phase growth method. The thickness of the protective layer 22 is usually 0.01 to 10 μm, preferably 0.1 to 5 μm,
Most preferably, it is 0.1 to 3 μm.

Further, an electrode protection layer may be provided on the electrode portion except the heat acting portion 17 on the protection layer 22. The characteristics required for the electrode protection layer include excellent ink resistance and heat resistance, and good electrical insulation. Therefore, it is required that the film has good film-forming properties, has few pinholes, and does not swell or dissolve in the used ink. Many materials satisfying the above conditions can be used as a material constituting the electrode protection layer. For example, silicone resin, fluorine resin, aromatic polyamide, addition polymerization type polyimide, metal chelate polymer, titanate, epoxy resin, phthalic acid resin, thermosetting phenol resin, P-
If a resin such as vinylphenol resin, Xyloc resin, or triazine resin is to be manufactured, and if a high-density multi-orifice type recording head is to be manufactured, an organic material that is extremely easy to perform fine photolithography processing besides the organic material described above. It is desirable to use.

A flow path is formed of a photosensitive resin on the heating element substrate configured as described above. A cavitation-resistant resin such as a photosensitive polyamide varnish or a photosensitive polyimide varnish is applied using an application means such as a spinner or a roll coater. The layer thickness of the photosensitive resin is not particularly limited, but if practicality as an ink jet recording head is considered, at least 5 to 100 μm
m, preferably 10 to 50 μm, and most preferably 15 to 50 μm. Therefore, it is preferable that the photosensitive resin can be laminated to such a thickness, and the commercially available photosensitive resin includes the above-mentioned photosensitive polyamide varnish, that is, Pleinite EF95, Toplon (Toplon),
Nylonprint or photosensitive polyimide, that is, Photonice VR-3140 and Selectyllux HTR-2 are preferably used.

The substrate on which the photosensitive resin is laminated in this way is subjected to the following processing such as exposure or development to form an ink flow path wall made of the photosensitive resin. In the following, the processing will be described by taking as an example the case where the photosensitive resin is Photonice VR-3140, but the method of forming the ink flow path wall may be any method according to the photosensitive resin used.

Prebaking is performed on the substrate on which the photosensitive resin is laminated, if necessary. After the completion of the pre-bake, a photomask having a desired pattern is overlaid on the photo nice VR-3140, and then exposure is performed through the photomask.

After the exposure, the unexposed portion of the photonice VR-3140 is developed using a developing solution DV-505 for the photonice VR-3140, and the unexposed portion is dissolved and removed, thereby forming a groove to be used as an ink flow path. To form

After dissolving and removing the unexposed portion in this manner, post-baking is performed to cure the exposed portion of the photo-nice VR-3140 remaining on the substrate, and the photo-nice VR-3140 as an ink flow path wall having a desired pattern on the substrate. To form a cured film. The method of forming a liquid type photosensitive resin such as Photonice VR-3140 has been described above, but it can also be formed using a photosensitive dry film. The substrate thus formed and a lid substrate for forming a ceiling portion of the flow path are joined via an adhesive layer. As the material of the lid substrate, the same material as the heating element substrate can be used. That is, silicon, glass, ceramics, and the like. A photosensitive dry film is provided on a substrate made of these materials in a semi-cured state, and after joining to the grooved substrate, heat is applied for full curing to join the heating element substrate and the lid substrate.

 Next, examples of the present invention will be described.

Example 1 (a) Head A: SiO ₂ as a heat storage layer on a glass substrate
μm, 2000 mm of Ta-SiO ₂ as heating element layer, Al as electrode
5,000 °, SiO ₂ as a protective layer, ₂ μm, and Ta as a second protective layer, 1500 °.

(B) Head B: Aluminum was provided as a heat transfer layer on a glass substrate at a thickness of 1 μm over the entire surface by sputtering, and then, similarly to the head A, an accumulation layer, a heating element layer, an electrode, and a protective layer were provided.

(C) Head C: 5 μm of SiC as a heat transfer layer on a glass substrate
m, after the entire surface was formed by CVD, a heat-generating portion similar to that of the head A was provided.

(D) the head D; with a glass substrate to an RF power supply side of the vacuum apparatus consisting of hydrogen and a hydrocarbon _{(CH 4, C 2 H 6} , C 3 H 8, C 4 H 10, C 2 H 4 , etc.) A high-frequency electric field (13.56 MHz) is applied to a parallel plate electrode in a gas atmosphere, and the source gas is radically and ion-decomposed by the generated glow discharge, and heat transfer of diamond-like carbon consisting of carbon atoms and hydrogen atoms on a glass substrate Layers were provided. The thermal conductivity of the diamond-like carbon by the above-described plasma CVD method was 0.8 J / s · cm · ° C. A heat-generating portion similar to that of the head A was provided on this heat transfer layer.

(E) Head E: 1 μm of Cr as a heat transfer layer on a glass substrate
After being provided on the entire surface by m-sputtering, a heat-generating portion similar to that of the head A was provided.

(F) Head F; zinc on the glass substrate as a heat transfer layer
After being provided on the entire surface by the μm sputtering, a heating section similar to that of the head A was provided.

Using these heads, drive voltage 23V, pulse width 5μ
s, the liquid was ejected at a drive frequency of 4.2 KHz, and the variation in the droplet speed and ejection direction after 5 minutes was evaluated. The results were as shown in Table 1 below. The number of heating elements of the heads A to F is all 512, and the arrangement density of the heating elements is 16 / mm.
And 24 types / mm were evaluated.

In addition, the state of bubbles in the head A and the head B is
Observation with a microscope revealed that in the case of the head A, shortly after the start of driving, minute and irregular bubbles were generated from all over the substrate around the heating element, and the bubbles were completely removed in the heating section. The growth and shrinkage are repeated without disappearing, and then large bubbles that do not grow and shrink adhere to the heat generating part, and eventually the heat generating element is destroyed,
That was the cause of the ejection failure. In the case of the head B, the above phenomenon was not observed, and the growth and disappearance of the bubbles were repeated normally. These results clearly show that the heat transfer layer allows stable bubble growth and disappearance without accumulating heat in the substrate, thereby reducing the variation in droplet speed and performing stable ejection. From the results shown in Table 1, the thermal conductivity of the heat transfer layer is preferably 0.58 J / s · cm · ° C. or more, and more preferably 2.0 J / s · cm · ° C. or more.

In addition, although the head F has a stable droplet speed, the ejection direction varies.
Looking at the expansion coefficients of the heat transfer layers of C, D, and E, head B = 31.5 × 10 ⁻⁶ / deg, head C = 4.8 × 10 ⁻⁶ / deg, head D = 4.5 × 10 ⁻⁶ / deg, head E = 11 × 10 ⁻⁶ / deg, head F = 39.7 × 10 ⁻⁶ / deg, the head F is very large, and the expansion coefficient of the glass substrate is 0.54 × 10 ⁻⁶ / deg. The difference is extremely large. Therefore, the heat transfer layer expanded due to the heat, causing variations in the discharge direction, and cracks and the like occurred, and the heat generating portion was destroyed. From this, it is better that the coefficient of linear expansion of the heat transfer layer is as small as possible, and it is better not to be significantly different from the substrate or the heat storage layer, usually 31.5 × 10 ⁻⁶ / deg, and further, 11 × 10 ⁻⁶ / deg or less. Preferably, there is. Further, 4.8 × 10 ⁻⁶ / deg or less is optimal.

Therefore, among the above-mentioned materials, preferred are aluminum, cadmium, gold, silver, dangsten, iron,
Simple substances such as copper, nickel, platinum, magnesium, molybdenum, beryllium, niobium, chromium, cobalt, iridium, palladium, silicon, calcium, and alloys thereof,
Mixtures, further, BeO, SiC, AlN, cubic BN, diamond-like carbon, etc., among which Si, BeO, S
iC, AlN, cubic BN, and diamond-like carbon are superior in terms of thermal conductivity, coefficient of linear expansion, electrical characteristics, and the like.

In addition, diamond-like carbon means i
-Sometimes referred to as carbon or, due to its crystalline nature, as amorphous carbon. In addition, a diamond thin film that is crystalline and has a structure similar to natural diamond due to lattice spacing and the like is also referred to as diamond-like carbon.

 Next, another embodiment of the present invention will be described.

Embodiment 2 FIG. 4 shows an embodiment of the pattern of the heat transfer layer 20-1. In the figure, 40 is a heat transfer layer, 41-1 to 41-5 are portions where no heat transfer layer is provided (cut portions), and 42-1 to 42-4 are portions where heat generating resistance layers are stacked. . FIG. 5 shows a heat storage layer 20-2 and a heating resistor layer 21- on the heat transfer layer of the pattern of FIG.
FIG. 3 is a YY cross-sectional view of a head in which 1 to 21-3, a protective layer 22, a flow path wall 25, and a lid substrate 14 are stacked. As can be seen from the above, a heat transfer layer is provided under each of the heat generating resistance layers 21-1, 21-2, and 21-3. However, since there is a cutout between adjacent heat generating resistance layers, for example, The heat generated in the heat-generating resistor layer 21-1 is transmitted through the heat-transfer layer to the adjacent heat-generating resistor layer 21-2, and although the heat-generating resistor layer 21-2 is not driven,
Bubbles may be generated, and the heating resistance layer 21-1
In the case where 21-2 are driven simultaneously or with a slight time difference, the ejection characteristics are not affected (so-called crosstalk). Further, heat is radiated from each heat generating resistance layer along the flow path direction, and sufficiently fulfills the purpose of the heat transfer layer. The above-mentioned crosstalk becomes more conspicuous as the distance between the heating elements is shorter.

In the heat transfer layer pattern as shown in FIG.
A head having the structure of (d) was prepared, and the droplet speed was evaluated. The number of heating elements of the head was 512, the array density was 16 / mm, the driving voltage and pulse width were the same, the driving frequency was increased to 5 KHz, and each heating element was driven simultaneously. Table 2 shows the results.

As can be seen from the results, the variation in the droplet speed was reduced to 5% or less despite the strict drive frequency.

In the embodiment of the present invention, the patterns as shown in FIG. 4 are used, but all the patterns as shown in FIG. 6 suitably realize the present invention.

In FIG. 6, (a) shows a structure in which a number of small cuts are provided in the heat transfer layer between the heat generating parts to reduce the heat transfer efficiency in the lateral direction.
(B) is a case in which a notch portion is provided sufficiently longer than the heat generating portion.
(C) is a diagram in which the heat transfer layer is separated for each heating part.

Further, in the present invention, since there is a notch beside the heat generating portion having the largest expansion, the notched portion serves to absorb the thermal expansion, and it is not necessary to consider the thermal expansion as described above. Further, in the case of a material having a low thermal expansion as described above, there is a feature that the stability in the ejection direction is further increased. In particular, in the case of FIGS. 6 (b) and 6 (c), that is, when the cutout portion is sufficiently longer than the heating element length (for example, twice or more), or when the heat transfer layer is separated for each heating element. Almost no need to consider thermal expansion.

FIG. 7 is a view showing still another bubble generating means. In this example, a pair of discharge electrodes 70 arranged on the inner wall side of the heat energy action section receives a high voltage pulse from a discharge device 71,
A discharge is generated in the recording liquid, and bubbles are instantaneously formed by heat generated by the discharge.

8 to 15 are diagrams showing specific examples of the discharge electrode shown in FIG. 7, respectively. In the example shown in FIG. Discharge (at low energy).

In the example shown in FIG. 9, two flat electrodes are used so that air bubbles are stably generated between the electrodes. The position of the generated bubble is more stable than the needle-shaped electrode.

In the example shown in FIG. 10, a substantially coaxial hole is formed in the electrode. Both holes of the two electrodes serve as guides, and the position of the generated bubbles is further stabilized.

The example shown in FIG. 11 is a ring-shaped electrode, and is basically the same as the example shown in FIG. 10, and is a modified embodiment thereof.

In the example shown in FIG. 12, one is a ring-shaped electrode and the other is a needle-shaped electrode. The ring-shaped electrode aims at stability of generated bubbles, and the needle-shaped electrode aims at efficiency by concentrating an electric field.

The example shown in FIG. 13 is one in which one ring-shaped electrode is formed on the wall surface of the heat energy action section. This aims at the easiness in manufacturing that the electrodes are formed two-dimensionally on the substrate, in addition to the effect of the example shown in FIG. A plurality of such planar electrodes having high density can be easily manufactured by vapor deposition (or sputtering) or photo-etching technology. Especially effective for multi-array.

In the example shown in FIG. 14, the ring-shaped electrode forming portion of the example shown in FIG. 13 is formed along the outer periphery of the electrode and is raised one step from the periphery. Again, the stability of the generated bubbles is aimed at, and it is more stable than that shown in FIG. 12 by adding a three-dimensional guide.

The example shown in FIG. 15 is different from the example shown in FIG. 14 in that the ring-shaped electrode forming portion has a structure in which it is dropped down from the surroundings. Is done.

Effects As is apparent from the above description, the present invention has the following effects.

(1) In the liquid jet recording apparatus of the first aspect, since the heat transfer layer is provided, good ejection performance can be obtained regardless of the type of the substrate. In particular, an ultra-high density multi-nozzle head of 16 nozzles / mm or more has an effect that a good ejection performance can be obtained, although it has been impossible to eject due to accumulation. Further, it is possible to use a substrate such as glass or alumina which can obtain a large area at low cost, and a full-line type head can be obtained at low cost. Also, even in high-frequency driving exceeding 4 KHz, extremely good heat radiation can be performed.

(2) A liquid jet recording apparatus having a portion in which no heat transfer layer is provided between thermal energy generators as described in claim 2 so as to drive at a very high density of 16 lines / mm or more and exceed 4 KHz. , Good ejection can be performed. Also,
Without causing crosstalk due to heat, variations in droplet speed can be made extremely small, and stable ejection can be performed. Further, it is possible to perform good discharge without causing a variation in the discharge direction due to thermal expansion of the heat transfer layer.

[Brief description of the drawings]

FIG. 1 is a view for explaining an embodiment of a liquid jet recording apparatus according to the present invention, and is a view for explaining a configuration of a bubble generating means using a heating resistor, and FIG. (B) is X- of (a)
FIG. 2 is a partial cutaway view of the case of cutting at a portion indicated by X-rays, FIG. 2 is a view for explaining the principle of ink ejection by bubble jet, FIG. 3 is an overall perspective view of a bubble jet recording head, FIG. FIG. 5 is a view showing one embodiment of the heat transfer layer pattern of the present invention, FIG. 5 is a sectional view taken along line YY of the pattern of FIG. 4, and FIGS. 6 (a) to 6 (c) show other patterns. Diagram,
FIG. 7 is a diagram for explaining an example of a bubble generating means using discharge, and FIGS. 8 to 15 are diagrams showing specific examples of the discharge electrode shown in FIG. 7, respectively. 13 ... substrate, 14 ... lid substrate, 15 ... orifice, 16 ...
Liquid discharging part, 17: heat acting part, 18: heat generating part, 19: heat acting surface, 20: lower layer, 20-1 ... heat transfer layer, 20-2 ...
Heat storage layer, 21 Heat generation resistance layer, 22 Protective layer, 23, 24
Electrodes, 25 ... channel walls.

Continuation of front page (56) References JP-A-62-90254 (JP, A) JP-A-64-1553 (JP, A) JP-A-57-185173 (JP, A) JP-A-64-56566 (JP) , A) JP-A-62-231761 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/05

Claims (2)

(57) [Claims] A discharge orifice for discharging the recording liquid as droplets, a liquid passage communicating with the discharge orifice, and a thermal energy generator for applying thermal energy to the recording liquid in the liquid passage. In the liquid ejecting recording apparatus provided on the lower layer wherein the thermal energy generator is laminated on a substrate, the liquid ejecting recording apparatus has an arrangement of the thermal energy generators of 16 lines / mm or more. A full-line type recording device arranged at a high density, wherein one thermal energy generator is
Driving at a driving frequency of 4 kHz or more, the lower layer is composed of at least a heat storage layer and a heat transfer layer, and the heat transfer layer has a thickness of 0.1 to 100 μm on a substrate by thin film formation by sputtering or CVD. A liquid jet recording apparatus characterized by being formed. A discharge orifice for discharging the recording liquid as liquid droplets, a liquid passage communicating with the discharge orifice, and a thermal energy generator for applying thermal energy to the recording liquid in the liquid passage. Wherein the thermal energy generator is provided on a lower layer laminated on a substrate, wherein the lower layer comprises at least a heat storage layer and a heat transfer layer. The apparatus is a full-line type recording apparatus in which the thermal energy generators are arranged at an array density of 16 lines / mm or more, wherein one thermal energy generator is driven at a drive frequency of 4 kHz or more, and the heat transfer layer is A thin film formed by sputtering or CVD on a substrate to a thickness of 0.1 to 100 μm, and at least a portion not provided between the adjacent heat energy generators. Liquid jet recording apparatus according to.