JP2914576B2 - Liquid jet recording apparatus and recording method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid jet recording apparatus and method, and more particularly, to a liquid jet recording apparatus and a recording method that enable gradation recording of 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, for example, a method disclosed in US Pat. No. 3,060,429 (Tele type method), in which droplets of a recording liquid are generated by electrostatic attraction, and the generated recording liquid is determined according to a recording signal. The recording is performed by controlling the electric field and selectively adhering the recording liquid to the recording member.

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 a method (Sweet method) disclosed in, for example, US Pat. No. 3,596,275, US Pat. No. 3,298,030, in which a droplet of a recording liquid whose charge amount is controlled by a continuous vibration generation method is generated, and the generated charging is performed. The recording is performed on the recording member by causing the controlled amount of the droplet to fly between the deflection electrodes to which a uniform electric field is applied.

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 to generate and atomize small droplets of a recording liquid by a continuous vibration generation method. This is the method of 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 method is, for example, a method (Stemme method) disclosed in US Pat. No. 3,747,120. This method is fundamentally different from the above three methods 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.

As described above, the conventional liquid jet recording method has advantages and disadvantages in terms of configuration, high-speed recording, multi-nozzle recording head, generation of satellite dots, fogging of a recorded image, and the like. There is a restriction that it can be applied only to applications that benefit.

However, this inconvenience can be almost completely eliminated by employing the ink jet recording method proposed earlier by the present applicant. The details of such an ink jet recording method are described in Japanese Patent Publication No. 56-9429, but in summary here, the ink in the liquid chamber is heated to generate air bubbles, causing a pressure increase in the ink. Then, ink is ejected from a fine capillary nozzle to record. Since then, many inventions have been made using this principle. As one of them, for example, Japanese Patent Publication No. 59-31943
There is an official gazette. This is characterized in that gradation recording is performed by applying a signal having gradation information to an electrothermal transducer having a heating section having a heating value adjustment structure and generating a heat quantity corresponding to the signal in the heating section. It was to be. Specifically, it has a structure in which the thickness of the protective layer, the heat storage layer, or the heating element layer changes gradually, or a structure in which the pattern width of the heating element layer changes gradually.

FIGS. 17 to 19 correspond to the above-mentioned JP-B-59-31943, respectively.
FIG. 4 is a cross-sectional structural view showing an example of the electrothermal converter disclosed in FIGS. 4 to 6 of the publication, in which 71 is a substrate, 72 is a heat storage layer,
73 is a heating element, 74 and 75 are electrodes, and 76 is a protective film. In the example shown in FIG. 17, the protective film 76 is provided with a thickness gradient from the electrode 74 side toward the electrode 75, so that the heating section is provided. From the surface of Δl, a gradient is provided for the amount of heat generated per unit time acting on the liquid in contact with the surface.

In the example shown in FIG. 18, the thickness of the heat storage layer 72 is gradually reduced from A to B in the heating portion Δl, and the heat generated by the heating element 73 is released to the substrate 71. A distribution is given to the amount of heat, and a gradient is provided for the amount of heat per unit time to be applied to the liquid in contact with the surface of the heat generating portion Δl.

In the example shown in FIG. 19, the heating element 73 is formed on the heat storage layer 72 by providing a gradient in the thickness of the heating element 73 in the heating section Δl. The amount of heat generated per unit time is controlled by the change in resistance at the time.

20 to 24 correspond to the above-mentioned Japanese Patent Publication No.
FIG. 31 is a plan view showing an example of an electrothermal converter disclosed in FIGS. 9 to 13 of Japanese Patent No. 31943, in which reference numeral 81 denotes a heat generating portion;
Reference numeral 3 denotes an electrode, and the example shown in FIG. 20 is such that the planar shape of the heating section 81 is rectangular, and the connection between the electrode 82 and the heating section 81 is smaller than the connection between the electrode 83 and the heating section 81. is there. In the examples shown in FIGS. 21 and 22, the central portion of the heat generating portion 81 has a planar shape smaller than both ends. In the example shown in FIG. 23, the heating section 81 has a trapezoidal planar shape, and electrodes 82 and 83 are connected to opposite sides of the trapezoid as shown in the figure.

In the example shown in FIG. 24, the central portion of the heat generating portion 81 has a planar shape wider than both ends. In these examples, a negative gradient is given to the current density from A to B of the heat generating portion. The size of droplets ejected by controlling the sharp change in the state of the liquid generated in the heat acting portion by changing the applied power level, thereby performing gradation recording It is.

However, as in the example shown in FIGS.
Forming a three-dimensional structure by a thin film forming technique has a drawback that it is practically impossible, and if it is made, it is very expensive. Further, when the pattern width was changed as shown in FIG. 20 to FIG. 24, disconnection was likely to occur where the pattern was the narrowest, and good results were not necessarily obtained from the viewpoint of durability.

On the other hand, JP-A-63-42872 discloses a similar gradation recording technique. This is also characterized in that the heating element layer has a three-dimensional structure, as in the technique of Japanese Patent Publication No. 59-31943, and has a drawback that the production is extremely difficult. As other gradation recording techniques, Japanese Patent Publication No. Sho 62-46358, Japanese Patent Publication No. Sho 62-46359, and Japanese Patent Publication No. Sho 62-48585 are known. Each of them selects a predetermined number of heating elements from a plurality of heating elements arranged in one flow path, or selects one from a plurality of heating elements having different heating values to generate bubbles. The size is changed or the ejection amount is changed by variably controlling the shift of the input timing of the drive signal to the plurality of heating elements. However,
In these technologies, since a plurality of heating elements correspond to one flow path or discharge port, the number of control electrodes connected to the plurality of heating elements increases, and the discharge ports are arranged at high density. It was impossible to do. Further, Japanese Patent Application Laid-Open Nos. 59-12463 and 59-124864 disclose a technique for controlling a discharge amount, which has a heating element and a bubble generating section different from a heating element for discharging. However, these also have the disadvantage that high density arrangement is difficult due to the presence of the bubble generating portion. Further, Japanese Patent Application Laid-Open No. 63-42869 discloses a technique for controlling the discharge amount by changing the number of times of generation of bubbles by changing the time for energizing the resistor. However, in a normal bubble jet, the energizing time is limited to several to several tens of microseconds, and when energizing for a longer time, the heating element is disconnected, so the technology of Japanese Patent Application Laid-Open No. 63-42869 is not It is not feasible.

As described above, in the prior art, various attempts have been made to perform gradation recording, but satisfactory results have not always been obtained from the viewpoint of manufacturing, durability, or high density arrangement. Absent.

In view of this point, the present applicant has previously filed Japanese Patent Application No. 1-192357. This is a liquid jet recording apparatus which is easy to manufacture, has excellent durability, is capable of high-density arrangement and is capable of gradation recording, and is an invention of a gradation recording method. Briefly summarizing a part of the invention, a discharge port for discharging a liquid to form a flying droplet and an electric heat for causing a state change of the liquid by heat to discharge the liquid. In a liquid jet recording apparatus including a liquid jet recording head having a conversion layer and a pair of electrodes electrically connected to the electrothermal conversion layer, heat is applied to the electrothermal conversion layer in an energizing direction. The heat radiation structure is formed so as to have a gradient, and the input energy is made variable according to the image information. More specifically, as shown in FIGS. 7 to 11, the ejection principle and the head structure are shown in FIG. In a so-called edge shooter type bubble jet, as described later, a heat dissipation structure is formed on (or below) the heating element so as to have a heat gradient in a direction of current supply, and the input energy can be varied according to image information. did Than it is. The present invention is an epoch-making liquid jet recording apparatus capable of high-density recording and gradation recording, and is a recording method. However, there is still room for improvement in terms of energy saving.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is easy to manufacture, excellent in durability, capable of high-density arrangement, capable of gradation recording, and energy-efficient liquid jet recording. Another object of the present invention is to provide a device, and to propose an energy-efficient gradation recording method.

Configuration In order to achieve the above object, the present invention provides (1) a discharge port for discharging a liquid to form a flying droplet, and a state change caused by heat in the liquid for discharging the liquid. An electrothermal transducer layer for squeezing, and a pair of electrodes electrically connected to the electrothermal transducer layer, wherein the discharge port and the electrothermal transducer layer are arranged at opposing positions; In a liquid jet recording apparatus including a liquid jet recording head that flies the liquid in a direction substantially perpendicular to the electrothermal transducer layer, a heat radiating structure is formed so as to generate a thermal gradient on the electrothermal transducer layer. Or (2) a discharge port for discharging a liquid to form a flying droplet, and applying heat to the liquid to discharge the liquid. Electricity to cause a state change due to A heat converter layer, and a pair of electrodes electrically connected to the electrothermal converter layer, wherein the discharge port and the electrothermal converter layer are arranged at opposing positions; In a liquid jet recording method using a liquid jet recording head that flies the liquid in a direction substantially perpendicular to the body layer,
The input energy is changed in accordance with the image information to cause a thermal gradient on the electrothermal transducer layer, and the amount of liquid discharged from the discharge port is changed by changing the size of bubbles generated on the electrothermal transducer layer. To change it, or
(3) a discharge port for discharging a liquid to form a flying droplet, an electrothermal transducer layer for causing the liquid to undergo a state change due to heat in order to discharge the liquid, and the electric heat A pair of electrodes electrically connected to the converter layer,
The liquid ejection recording apparatus including a liquid ejection recording head that is disposed at a position where the discharge port and the electrothermal transducer layer face each other and that ejects the liquid in a direction substantially perpendicular to the electrothermal transducer layer. A heat dissipation structure is formed so as to generate a thermal gradient below the electrothermal transducer layer, and the input energy is made variable according to image information, or
(4) a discharge port for discharging liquid to form flying droplets, an electrothermal transducer layer for causing the liquid to undergo a state change due to heat in order to discharge the liquid, and the electric heat A pair of electrodes electrically connected to the converter layer,
In the liquid ejection recording method using a liquid ejection recording head that ejects the liquid in a direction substantially perpendicular to the electrothermal conversion layer, the discharge port and the electrothermal transducer layer are arranged at opposing positions. A liquid discharged from the discharge port by changing input energy according to image information, causing a thermal gradient under the electrothermal transducer layer, and changing the size of bubbles generated on the electrothermal transducer layer. Or (5) a discharge port for discharging a liquid to form a flying droplet, and a state change caused by heat in the liquid for discharging the liquid. And a pair of electrodes electrically connected to the electrothermal converter layer, wherein the discharge port and the electrothermal converter layer are disposed at opposing positions, Almost perpendicular to the heat conversion layer In a liquid jet recording apparatus having a liquid jet recording head for flying the liquid, a heat radiating structure is formed so as to generate a thermal gradient on the electrothermal transducer layer, and the heat radiating structure is formed of the pair of electrodes. And (6) a discharge port for discharging a liquid to form a flying droplet and a discharge port for discharging the liquid. An electrothermal converter layer for causing the liquid to undergo a state change due to heat, and a pair of electrodes electrically connected to the electrothermal converter layer, wherein the discharge port and the electrothermal converter In a liquid jet recording apparatus including a liquid jet recording head that is disposed at a position facing the liquid jet head and that jets the liquid in a direction substantially perpendicular to the electrothermal transducer layer, a heat is applied below the electrothermal transducer layer. Create a gradient The heat dissipation structure is formed so that, a structure in which heat radiation structure also serves as one of the pair of electrodes, in which characterized in that a variable input energy in accordance with image information. Hereinafter, a description will be given based on an example of the present invention.

FIG. 7 is a view for explaining the operation of a bubble jet head as an example of an ink jet head to which the present invention is applied, FIG. 8 is a perspective view showing an example of a bubble jet head, and FIG. A lid substrate (FIG. 9 (a)) and a heating element substrate (FIG. 9 (b)) which constitute the head shown in FIG.
FIG. 10 is a perspective view of the lid substrate shown in FIG. 9 (a) viewed from the back side, where 21 is a lid substrate,
22 is a heating element substrate, 23 is a recording liquid inlet, 24 is an orifice, 25 is a flow path, 26 is a region for forming a liquid chamber, 27 is an individual (independent) electrode, 28 is a common electrode, and 29 is a heating element. (Heat), 30 is ink, 31 is bubbles, and 32 is flying ink droplets. The present invention is applied to such a bubble jet type liquid jet recording head.

First, ink ejection by bubble jet will be described with reference to FIG. 7. (a) is a steady state, and the surface tension of the ink 30 and the external pressure are in an equilibrium state at the orifice surface.

3B shows a state in which the heater 29 is heated until the surface temperature of the heater 29 sharply rises and boiling development occurs in the adjacent ink layer, and minute bubbles 31 are scattered.

(C) shows a state in which the adjacent ink layer, which is rapidly heated on the entire surface of the heater 29, is instantaneously vaporized to form a boiling film, and the bubbles 31 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 30 corresponding to the volume of the bubble is pushed out from the orifice surface. At this time, no current is flowing through the heater 29, and the surface temperature of the heater 29 is decreasing. The maximum value of the volume of the bubble 31 is slightly delayed from the timing of applying the electric pulse.

(E) shows a state where the bubble 31 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. .

(F) is a state in which the bubble 31 further contracts, 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 becomes a droplet and moves in the direction of the recording paper.
Flying at a speed of 10m / sec.

(G) is a 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.

FIG. 11 is a cutaway view of the essential part of the above-described bubble jet type inking jet recording head, which is generally called an edge shooter. FIG. 12 is a cross-sectional view of a main part of what is called a side shooter with respect to the edge shooter, and FIG. 13 is a view showing the operation principle thereof, as in FIG. From the state, the state shown in (d) is reached, and thereafter, the state returns to (e) in the same state as in (a), during which the droplet 32 is ejected. In such a bubble jet technology, ink ejection is performed by a change in the volume of generated bubbles.When examining the behavior of bubble generation, pulsed driving energy is input to the heating element, and when bubbles are generated, bubbles are generated. The growth-shrinkage is largely controlled by the inertia, and it is difficult to freely change the growth speed and size. When one heating element generates bubbles and ejects ink, it may or may not be necessary to generate bubbles. In this case, it is apt to be a binary drive for ejecting or not ejecting ink, and it is difficult to perform a so-called multi-value drive for freely changing the bubble size and continuously changing the ink ejection amount. Was. In order to overcome this difficulty, the present applicant has proposed Japanese Patent Application No. 1-192357, the principle of which is described below.

FIG. 14 is a structural view of a main part (heating element) of the bubble jet liquid jet recording apparatus according to Japanese Patent Application No. 1-192357, FIG. 14 (a) is a plan view, and FIG. A sectional view taken along the line B is shown, in which 10 is a substrate, 11 is a heat storage layer, 12 is a heating element layer, 13 is a control electrode, 14 is a ground electrode, 15 is a protective layer, 16 is a radiator,
Reference numeral 17 denotes an insulating layer, which is disclosed in Japanese Patent Application No. 1-192357.
As shown in FIG. 14, a heat radiator 16 is provided on the heat generating layer 12. The heat radiator 16 is not provided uniformly on the entire surface of the heating element layer 12, but the area covering the heating element layer 12 changes from the control electrode 13 side to the ground electrode 14 side as shown in FIG. Is provided. By doing so, on the heating element layer, it is possible to have a thermal gradient in the direction of conduction by the effect of the heat radiator. As a material for forming the radiator, Al, Au, or the like, which generally has a high thermal conductivity and can easily form a thin film such as vapor deposition and sputtering and facilitate fine processing such as photoetching, is preferably used. Japanese Patent Application No. 1-19235
In the publication No. 7, the heat dissipating body is planar (two-dimensional) in this way.
Therefore, there is an advantage that it can be easily and simply made in terms of manufacturing or structure. In the case of FIG. 14, the radiator 16 is formed in direct contact with the heating element layer, but the pattern of the radiator 16 is grounded so that the radiator 16 does not serve as a ground electrode. Appropriate insulating treatment 17 is performed without contacting the electrode 14. With respect to such a head having a thermal gradient on the heating element layer, Japanese Patent Application No. 1-192357 further changes the input energy to the heating element layer according to image information. Generally, in the bubble jet technique, when air bubbles are generated on the heating element layer by the film boiling phenomenon, it is necessary that the surface temperature on the heating element layer instantaneously reaches a certain temperature or more. In other words, in order for film boiling to occur, it is necessary that the temperature rises above a certain critical temperature. However, if a region where the critical temperature is reached is formed at any position on the heating element layer, the size of generated bubbles Can be changed arbitrarily. Fig. 15 shows the principle. FIG. 15 shows bubbles generated by dotted lines in the cross section of FIG. As described above, in Japanese Patent Application No. 1-192357, the heat radiator 16 provided on the heating element layer 12 has a thermal gradient on the heating element layer in the direction of current flow. Therefore, by changing the input energy from a small value to a large value, the critical point position of the bubble generation due to the film boiling sequentially moves according to the thermal gradient. As a result, as shown by the dotted line in FIG. 15, the bubbles 18 gradually increase from small bubbles 1 to 2, 3, and 4.

FIG. 16 is a configuration diagram of a main part (heating element) of a bubble jet liquid jet recording apparatus that does not perform normal gradation recording. No.
The major difference between FIG. 14 and FIG. 16 lies in the presence or absence of the heat radiator 16. Japanese Patent Application No. 1-192357 is an invention having the effect by providing a heat radiator 16, but from a different viewpoint, the heat is radiated by the heat radiator 16, so that a normal bubble jet as shown in FIG. There is an aspect that energy consumption is larger than that of the liquid jet recording apparatus. In other words, if both recording devices try to eject ink at approximately the same flying speed, Japanese Patent Application No. 1-192357 requires input of extra energy for the heat escaping by the radiator 16. That is.

By the way, in the so-called side shooter type bubble jet as shown in FIGS. 12 and 13 described above, a discharge port is provided at a position facing the heating element, and the ink is supplied in a direction in which bubbles grow on the heating element. Because it has a flying structure,
It is known that, since the pressure for causing ink to fly due to the generation of air bubbles is efficiently transmitted to the ink, it is superior to the edge shooter type in terms of energy consumption. The present inventors have paid attention to this point, and formed a heat radiating structure so as to have a heat gradient in a heating element portion of a side shooter type bubble jet liquid jet recording apparatus, and made it possible to vary input energy according to image information. Energy loss due to heat dissipation is compensated by the high efficiency of the side shooter type, and the critical film boiling temperature region in the heating element can be easily changed by the action of the heat dissipation structure with a thermal gradient and the change in input energy. At the very least, they found that the size of the generated bubbles could be changed and the ink ejection amount could be changed continuously. In other words, it is intended to propose a recording device that can perform gradation recording with low energy consumption.

1 (a) to 1 (c) show a main part of a liquid jet recording head according to the present invention, wherein FIG. 1 (a) is a plan view and FIG. 1 (b) is a sectional view taken along line AA of FIG. 1 (a). Figure, Figure (c) is Figure (a)
FIG. Here, for the sake of simplicity, the discharge port portion is omitted, and only the heating element substrate is shown.

In the figure, 40 is a substrate, 41 is a heat storage layer, 42 is a heating element layer, 43 is a radiator protection layer, 44 is a heat dissipation structure, 45 is a protection layer, 46 is a control electrode (layer), and 47 is a ground electrode (layer). ) And 48 are heating elements, and 49 is a heating element.

This heating element substrate was prototyped by the following method.

First, a silicon wafer is thermally oxidized to
The heat storage layer 41 is formed by growing an O ₂ film by 1.5 μm. The HfB ₂ is then heat layer 42 to 2500Å sputtering, further 1.2μm sputtered electrode layer Al thereon. Then, by performing photolithography and etching techniques twice, first, a pattern having a two-layer structure of the heating element layer 42 and the electrode layer is formed. The heating element 49 having a shape is exposed. In this state, when a pulse-like current is applied between the control electrode 46 and the ground electrode 47, the heating element 48 generates Joule heat, but since the recording head of the present invention comes into contact with the recording liquid, conduction between the two electrodes is prevented. In order to prevent the heating element layer 42 from being corroded from the recording liquid, 1 μm of SiO ₂ is sputtered as a protective layer 45 over the entire surface. Further, a heat dissipation structure 44 which is a feature of the present invention is formed thereon. In this case, the heat dissipation structure 44 is formed by sputtering Al over the entire surface to a thickness of 1.5 μm, followed by photolithography and an etching technique to form a pattern as shown by hatched portions in FIG. That is, as a main part of the heat dissipation structure 44,
The heat-dissipating structure 44 has a heat-dissipating effect on the square-shaped heat-generating part 48, which has a large heat-dissipating effect on the upper and lower sides of the figure and hardly dissipates heat at the center. Thereafter, in order to prevent Al of the heat radiation structure material from being corroded by the recording liquid, SiO ₂ was applied to the entire surface as a heat radiation protection layer 43 to a thickness of 1 μm.
Sputtered.

The above is one embodiment in which the heating element substrate was experimentally manufactured. Materials that can be used in addition to this embodiment will be described below.

As a material constituting the substrate, ceramics such as alumina, glass, or the like is used in addition to silicon. At present, silicon having high thermal conductivity is the most preferable material in consideration of availability and the like, but alumina or glass may be used in consideration of cost and the like.

When alumina is used for the substrate, the heat storage layer 41 is made of a glass material known as a glaze layer.
When glass is used as the substrate, SiO ₂ may be formed by sputtering, but since the glass itself serves as a heat storage layer, no special heat storage layer needs to be provided.

As the material constituting the heating element, the useful, for example, a mixture of Tantaru SiO _2, tantalum nitride, nichrome, silver - palladium alloy, silicon semiconductor or hafnium, lanthanum, zirconium, titanium, tantalum, tungsten, molybdenum, Boride of a metal such as niobium, chromium, and vanadium;

Among these materials constituting the heating element, metal borides can be mentioned as being particularly excellent. Among them, hafnium boride has the most excellent properties, followed by zirconium boride and boron boride. Lanthanum boride, tantalum boride,
The order is vanadium boride and niobium boride.

The heating element can be formed using a method such as electron beam evaporation or sputtering using the above materials.
The film thickness of the heating element is determined according to its area, material, shape and size of the heat acting portion, and furthermore, power consumption in an actual plane so that the amount of heat generated per unit time is as desired. However, it is usually 0.001 to 5 μm, preferably 0.01 to 1 μm.

As the material constituting the electrode, many of the commonly used electrode materials are effectively used, and specifically, for example, Al, Ag, Au, Pt, Cu, etc. are used. It is provided at a predetermined position in a predetermined size, shape, and thickness by a technique such as vapor deposition.

The property required for the protective layer is to protect the heating element from the recording liquid without preventing the heat generated by the heating element from being effectively transmitted to the recording liquid. Useful materials for forming the protective layer include, for example, silicon oxide, silicon nitride, magnesium oxide, aluminum oxide, tantalum oxide, zirconium oxide, and the like, which are formed by using a technique such as electron beam evaporation or sputtering. Can be formed. The thickness of the protective layer is usually 0.
01-10 μm, preferably 0.1-5 μm, optimally 0.1-3
μm is desirable.

The protective layer is rather for preventing the heating element from being chemically corroded from the recording liquid. However, in the recording head of the present invention, bubbles are generated in the recording liquid. As a result, a cavitation action force is generated when the bubble shrinks and disappears. In order to physically protect the heating element and its protective layer from the cavitation action force, durability is improved by further providing a metal layer such as Ta. The thickness of the Ta layer is preferably from 1000 to 5000 °. When the Ta layer as the anti-cavitation layer is applied to the embodiment of the present invention shown in FIG. 1, the Ta layer is formed so as not to hinder the action of forming the heat gradient of the heat dissipation structure already formed. There is a need to.
Specifically, in the example of FIG. 1, there is no problem if a Ta layer is provided on the radiator protection layer because it is thermally insulated from the radiator structure. The heat dissipation structure material is preferably provided with a material having a high thermal conductivity. Generally, the same material as the electrode material is used in consideration of ease of pattern formation. That is, Al, Ag, Au, Pt, Cu
And so on. Since the same material as the electrode can be used for this material, the heat dissipation structure is formed integrally with the ground electrode as described later. In this way, good heat dissipation efficiency due to direct contact with the heating element and simplification of the pattern configuration can be achieved.

Further, although omitted in FIG. 1 for simplicity of explanation, a protective layer of polyimide or the like is formed in an area of 1 to 5 μm in a region where the recording liquid is in contact except for the vicinity of the heating element.

This is mainly for protecting the electrodes from the recording liquid, and is called an electrode protection layer. In the present invention, a photonice (manufactured by Toray Industries, Inc.) was formed to a thickness of 1.2 μm by spin coating, and the pattern of the bonding pad portion (not shown) connected to the vicinity of the heating element portion and the lead wire was formed by ordinary photolithography.

The above is a specific method for manufacturing the heating element substrate according to one embodiment of the present invention. In the present invention, in order to cause the recording liquid to fly in a direction substantially perpendicular to the heating element surface as shown in FIG.
A discharge port is formed at a position facing the heating element. In the figure, 50
Is a heat generating substrate, 51 is a heat dissipation structure, 52 is a channel forming member (dry film resist), 53 is a recording liquid supply channel, 54 is an orifice plate, and 55 is a discharge port.

As a method of forming the discharge ports, in the present invention, an independent recording liquid supply channel 53 is formed for each heating element on the heating element substrate 50, and an orifice plate 54 having a discharge port 55 formed thereon is joined thereto. Formed. As a method of forming a recording liquid forming channel, a photosensitive resin known as a dry film resist was laminated on a heating element substrate, and a pattern was formed by exposure to development by a usual photolithography technique. The usual method of using a dry film resist is to use a mask as a mask for performing a plating or etching step after forming a pattern and then remove it. However, in the present invention, after forming a pattern, a heating element is directly used as a channel forming member. Leave it on the substrate. The thickness of the dry film resist used in the present invention is 20 μm
Therefore, the thickness (height) of the channel forming member is the same of 20 μm. In the present invention, the orifice plate is joined to the recording liquid supply channel thus formed so that the discharge port is located substantially above the heating element. In the present invention, Ni photo electroforming is employed as a method for manufacturing an orifice plate. The size of the discharge port of the orifice plate was φ35 μm, and the thickness was 50 μm.

FIG. 2 is a diagram for explaining the principle that the ejection amount of the recording liquid can be changed according to the present invention, and is shown by an example of the heating element substrate having the configuration of the embodiment of FIG. In FIG. 2, as the driving pulse, that is, the input energy to the heating element changes from small to medium to large, in the generated bubble plan view, the bubbles (hatched portions in the figure) protrude from both sides and finally merge. Also, in the cross-sectional view showing the bubble and the discharge state, a cross-sectional view of the growth bubble,
This shows how the flying droplet becomes larger or smaller according to the size of the bubble.

The above is the description of one embodiment in which the heat dissipation structure is formed on the heating element layer. Next, an example in which the heat dissipation structure is formed below the heating element layer will be described. FIGS. 4 (a) and 4 (b) show an example thereof. Basically, the heating element layer and the heat radiating element protection layer in FIG. 1 are formed on the heat storage layer. That is, only the order of pattern lamination is changed. Here, the heat radiator protection layer will be referred to as a heat insulating layer, but the material, thickness, and the like are the same.

5 (a) to 5 (d) show another embodiment of the present invention, in which a heat dissipation structure and an electrode (for example, a ground electrode) are provided.
Is also used. As described above, the heat dissipation structure and the electrodes are formed by using the same material (such as Al and Au) and the same manufacturing method (such as sputtering and etching). In addition, a function as an electrode can be provided at the same time. By doing so, the pattern configuration is simplified, the cost is reduced, or the pattern configuration is simplified. It is possible to prevent a decrease in lifetime due to thermal strain of the pattern layer. An example of the manufacturing method will be briefly described with reference to FIG. First, a thermal oxide film-formed Si
A heating element layer 42 is formed on the wafer (a), and then a control electrode
46 is formed and connected to the heating element layer 42 (b). Further, an SiO ₂ film is formed as an insulating layer on the entire surface except for a portion connected to a ground electrode described later and a lead wire take-out portion (bonding pad portion) (c). Thereafter, a heat radiating structure 44 and a ground electrode 47 are formed in such a pattern that a thermal gradient is generated in the heating element (FIG. 1D). Thereafter, a protective layer, a cavitation-resistant layer, an electrode protective layer, etc. as described in FIG. Is formed to complete the heating element substrate. The materials and thicknesses used are almost the same as those described with reference to FIG.

The above is one embodiment of the structure in which the heat dissipation structure and the electrode are used together and formed on the heating element layer. However, as another embodiment, the heat dissipation structure and the electrode are also used and formed below the heating element layer. Is also a preferred example of the present invention. Basically, as described with reference to FIG. 4, it is only necessary to change the order of forming the stacked patterns.

The method of forming the heat radiating structure above and below the heating element layer and the method of forming the heat radiating structure and the electrode both above and below the heating element layer have been described above. It is an example and the present invention is not limited to these examples. Actually, when designing and manufacturing the head of the present invention, each pattern is called a photolithographic technique,
Although it is formed by a wafer process such as a sputtering technique and an etching technique, in consideration of a process problem, for example, a problem relating to poor step coverage, a problem that a base (lower pattern) is removed by etching, and the like, An optimal layer configuration or thickness determination or material determination is made.

Next, another example of the shape of the heat radiation structure of the present invention is shown in FIGS. 6 (a) to (e). Figures (a) to (d) show examples of a heat dissipation structure (hatched portion) formed above or below a square heating element layer, and Figure (e) shows a round heating element layer. An example of a heat dissipation structure (shaded portion) formed above or below is shown. In the figure, the arrow indicates that the input energy is small →
This indicates a direction in which the critical film boiling region in the heating element portion expands when it is changed to a large value, in other words, a direction in which the bubble generation region expands as the input energy increases. Although a structure in which the heat radiation area is large in the center as shown in FIGS. (C), (d) and (e) is not shown, a heat radiation material penetrating and connected to the heating element layer is formed in the lower layer. Improves heat dissipation efficiency.

Next, conditions actually driven by the head shown in FIGS. 1 and 3 according to an embodiment of the present invention will be described below.

Heating element size 40 × 40μm (resistance 30Ω) Outlet diameter φ35μm Driving voltage 15-30V Pulse width 3.2μsec Continuous response frequency 4.5K Hz Ink used for Canon BJ130 ink Printing pixel diameter 50μm (at 15V)-140μm (at 30V) )
(Pixel diameter is a value on NM matte coated paper manufactured by Mitsubishi Paper Mills) Under the above conditions, in the present invention, the pixel diameter could be changed from 50 to 140 μm.
In the head described in No. 192357, that is, the edge shooter type head, it is necessary to obtain 19 to 38 pixels in order to obtain almost the same pixel diameter.
V (pulse width: 6 μsec) is required, and it can be seen that energy consumption was considerably reduced by the present invention.

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

1. Since the heat dissipation structure can be easily formed two-dimensionally using the photolithography technology, high-density arrangement is possible and gradation recording is possible (corresponding to claims 1, 2, 3, and 4).

2. A heat-dissipating structure is formed on the head that flies in a direction almost perpendicular to the surface of the heating element, and gradation recording is performed. Therefore, if the recording liquid flying efficiency is higher than that of the conventional type (edge shooter type), energy-saving driving is possible. (Corresponding to claims 1, 2, 3, 4).

3. The pattern structure is simplified by using both the heat dissipation structure and the electrode, thereby reducing the cost or
Since the heat distortion can be reduced, the life time is improved (corresponding to claims 5 and 6).

[Brief description of the drawings]

1 (a) to 1 (c) are configuration diagrams of a liquid jet recording head according to the present invention, and FIGS. 2 (a) to 2 (i) explain the principle by which the jetting amount of a recording liquid can be changed according to the present invention. FIG. 3 is a structural view for causing the recording liquid to fly in a direction substantially perpendicular to the surface of the heating element, and FIGS. 4 (a) and 4 (b) show a heat radiation structure formed below the heating element layer. Figure 5 (a)
6A to 6D are views showing another embodiment of the present invention, FIGS. 6A to 6E are views showing another embodiment of the shape of the heat dissipation structure, and FIG. 7 is a view showing the present invention. FIG. 8 is a diagram for explaining the operation of a bubble jet head as an example of an ink jet head to which the present invention is applied, FIG. 8 is a perspective view showing an example of a bubble jet head, FIG. 9 is an exploded perspective view, and FIG. , A view of the lid substrate from the back, FIG. 11 is a sectional view of a principal part of a bubble jet type ink jet recording head, FIG. 12 is a sectional view of a principal part of a side shooter, FIG. 13 is an operation of FIG. FIG. 14 is a diagram showing the principle, FIG. 14 is a configuration diagram of a heating unit of the previously proposed bubble jet liquid jet recording apparatus, FIG. 15 is a diagram for explaining the principle of changing the size of bubble generation, and FIG. FIG. 17 is a configuration diagram of a heating element portion of a bubble jet liquid jet recording apparatus that does not perform normal gradation recording. 24 to 24 are diagrams each showing a configuration of a conventional heating element layer. FIGS. 17 to 19 are examples in which the thickness of a protective layer, a heat storage layer, or a heating element layer is gradually changed. 20 to 24 are examples in which the pattern width of the heating element layer is gradually changed. 40 ... substrate, 41 ... heat storage layer, 42 ... heating element layer, 43 ... heat dissipation body protection layer, 44 ... heat dissipation structure, 45 ... protection layer, 46 ...
Control electrode 47 47 Earth electrode 48 Heating element 49
Heating element.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shuji Motomura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd. (72) Inventor Masafumi Kamonaga 1-3-6 Nakamagome, Ota-ku, Tokyo No. Ricoh Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) B41J 2/205 B41J 2/05

Claims (6)

(57) [Claims] An ejection port for ejecting a liquid to form a flying droplet; an electrothermal transducer layer for causing the liquid to undergo a state change by heat in order to eject the liquid;
A pair of electrodes electrically connected to the electrothermal transducer layer, wherein the discharge port and the electrothermal transducer layer are disposed at opposing positions, and In a liquid jet recording apparatus including a liquid jet recording head for flying the liquid in a vertical direction, a heat radiating structure is formed so as to generate a thermal gradient on the electrothermal transducer layer, and an input energy according to image information is formed. A liquid jet recording apparatus, wherein 2. An ejection port for ejecting a liquid to form a flying droplet, and an electrothermal transducer layer for causing the liquid to undergo a state change due to heat in order to eject the liquid.
A pair of electrodes electrically connected to the electrothermal transducer layer, wherein the discharge port and the electrothermal transducer layer are disposed at opposing positions, and In a liquid jet recording method using a liquid jet recording head that flies the liquid in a vertical direction, a thermal gradient is generated on the electrothermal transducer layer by changing input energy according to image information, and the electrothermal transducer layer is formed. A liquid jet recording method, wherein the amount of liquid ejected from the ejection port is changed by changing the size of the bubble generated above. 3. An ejection port for ejecting a liquid to form a flying droplet, and an electrothermal transducer layer for causing the liquid to undergo a state change due to heat in order to eject the liquid.
A pair of electrodes electrically connected to the electrothermal transducer layer, wherein the discharge port and the electrothermal transducer layer are disposed at opposing positions, and In a liquid jet recording apparatus including a liquid jet recording head that flies the liquid in a vertical direction, a heat dissipation structure is formed so as to generate a thermal gradient below the electrothermal transducer layer, and input is performed according to image information. A liquid jet recording apparatus having variable energy. 4. An ejection port for ejecting a liquid to form flying droplets, and an electrothermal transducer layer for causing the liquid to undergo a state change due to heat in order to eject the liquid.
Having a pair of electrodes electrically connected to the electrothermal transducer layer, wherein the discharge port and the electrothermal transducer layer are disposed at opposing positions, and with respect to the electrothermal transducer layer, In a liquid jet recording method using a liquid jet recording head that flies the liquid in a substantially vertical direction, an input energy is changed in accordance with image information to generate a thermal gradient below the electrothermal transducer layer, A liquid ejection recording method, wherein the amount of liquid ejected from the ejection port is changed by changing the size of bubbles generated on the heat conversion body layer. 5. An ejection port for ejecting liquid to form flying droplets, and an electrothermal transducer layer for causing the liquid to undergo a state change due to heat in order to eject the liquid.
Having a pair of electrodes electrically connected to the electrothermal transducer layer, wherein the discharge port and the electrothermal transducer layer are disposed at opposing positions, and with respect to the electrothermal transducer layer, In a liquid jet recording apparatus including a liquid jet recording head that flies the liquid in a substantially vertical direction, a heat radiating structure is formed so as to generate a thermal gradient on the electrothermal transducer layer, and the heat radiating structure is The structure also serves as one of a pair of electrodes,
A liquid jet recording apparatus wherein input energy is made variable in accordance with image information. 6. An ejection port for ejecting a liquid to form a flying droplet, and an electrothermal transducer layer for causing the liquid to undergo a state change due to heat in order to eject the liquid.
A pair of electrodes electrically connected to the electrothermal transducer layer, wherein the discharge port and the electrothermal transducer layer are disposed at opposing positions, and In a liquid jet recording apparatus including a liquid jet recording head for flying the liquid in a vertical direction, a heat radiating structure is formed so as to generate a thermal gradient below the electrothermal transducer layer, and the heat radiating structure is The structure also serves as one of a pair of electrodes,
A liquid jet recording apparatus wherein input energy is made variable in accordance with image information.