JP3046329B2 - Liquid jet recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid ejection recording apparatus, and more particularly, to a liquid ejection recording apparatus that enables 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 method of the generated recording liquid droplets is roughly classified into several types.

First, the first system is, for example, a system disclosed in US Pat. No. 3,060,429 (Tele type system), in which droplets of a recording liquid are generated by electrostatic attraction, and the generated droplets of the recording liquid are converted according to a recording signal. The electric field is controlled, and recording is performed by selectively adhering the recording liquid droplets onto the recording member.

More specifically, an electric field is applied between the nozzle and the accelerating electrode to discharge evenly charged droplets of the recording liquid from the nozzle, and the discharged droplets of the recording liquid are 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 system is a system (Sweet system) disclosed in, for example, US Pat. No. 3,596,275, US Pat. No. 3,298,030, and generates small droplets of a recording medium whose charge amount is controlled by a continuous vibration generation method. 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. A droplet of a recording medium having a controlled charge amount is deflected in accordance with the added charge amount when flying between deflection electrodes to which a constant electric field is uniformly applied, and the droplet 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, which 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 electric heat exchanger 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. 28 to 30 show the above-mentioned JP-B-59-31943, respectively.
FIG. 4 is a sectional structural view showing an example of an electric heat exchanger 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. 28, 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. 29, the thickness of the 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. 30, the heating element 73 is formed on the accumulation 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.

FIG. 31 to FIG.
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. In the example shown in FIG. 31, 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 FIG. 32 and FIG. 33, the central portion of the heat generating portion 81 has a planar shape thinner than both ends. In the example shown in FIG. 34, the heat generating portion 81 has a trapezoidal planar shape, and electrodes 82 and 83 are connected as shown in the figure on opposite sides of the trapezoid that are not parallel.

In the example shown in FIG. 35, 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 state change of the steep liquid generated in the heat acting portion by changing the applied power level, thereby changing the size of the discharged liquid, 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 FIGS. 31 to 35, disconnection was likely to occur where the pattern was narrowest, and good results were not necessarily obtained in terms 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. 62-46358, Japanese Patent Publication No. 62-46359, and Japanese Patent Publication No. 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. 59-12863 and 59-124864 disclose a technique for controlling a discharge amount, which has a heating element and a bubble generating section separate 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 a resistor. However, in a normal bubble unit, the energization time is limited to several to several tens of microseconds, and if the energization time is longer than that, the heating element is disconnected, so that the technology of JP-A-63-42869 is not practical in terms of durability. 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.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a liquid jet recording apparatus which is easy to manufacture, has excellent durability, and can perform gradation recording capable of high-density arrangement. Is to do.

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 causing a state change of the liquid due to heat to discharge the liquid. In a liquid jet recording apparatus including a liquid jet recording head having an electrothermal transducer layer for, and a pair of electrodes electrically connected to the electrothermal transducer layer, the electrothermal transducer layer, A heat radiating structure having a two-dimensional planar structure is formed such that the length of the current flowing direction is longer than the length of the direction perpendicular to the current flowing direction, and has a thermal gradient in the current flowing direction on the electrothermal transducer layer. Or (2) an ejection port for ejecting a liquid to form a flying droplet, and applying heat to the liquid to eject the liquid. Electric heat to cause a state change In a liquid jet recording apparatus using a liquid jet recording head having a converter layer and a pair of electrodes electrically connected to the electrothermal converter layer, the electrothermal converter layer has a direction in which the current flows. Forming a heat dissipation structure having a two-dimensional planar structure having a length longer than a length in a direction perpendicular to a current application direction and a thermal gradient in a current application direction below the electrothermal transducer layer; (3) In the above (1) or (2), the radiator also serves as one of the pair of electrodes. It is characterized by having. Hereinafter, a description will be given based on an example of the present invention.

FIG. 22 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. 23 is a perspective view showing an example of a bubble jet head, and FIG. A lid substrate (FIG. 24 (a)) and a heating element substrate (FIG. 24 (b)) constituting the head shown in FIG.
FIG. 25 is a perspective view of the lid substrate shown in FIG. 24 (a) viewed from the back side, where 21 is a lid substrate,
22 is a heating element substrate, 23 is a recording plate 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, 29 is a heating element (heater),
Reference numeral 30 denotes ink, 31 denotes air bubbles, and 32 denotes flying ink droplets. The present invention is applied to such a bubble jet type liquid jet recording head.

First, the ink ejection by the bubble jet will be described with reference to FIG. 22. (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. 26 is a view showing a typical example for explaining a main configuration of the liquid jet recording head as described above. FIG. 26 (a) is a detailed front partial view of the bubble jet recording head viewed from the orifice side. , FIG. 26 (b)
FIG. 3A is a partial cross-sectional view when cut along a portion indicated by a chain line XX in FIG.

In the recording head 41 shown in these figures, a predetermined number of grooves having a predetermined linear density and a predetermined width and depth are provided on a substrate 43 provided with an electrothermal transducer 42 on the back surface thereof. Grooved plate
By joining the substrate 44 so as to cover the substrate 43, a liquid ejection portion 46 including an orifice 45 for flying a liquid is formed. The liquid discharge section 46 has an orifice
The heat energy generated by the heat energy generated by the heat exchanger 45 and the electric heat exchanger 42 acts on the liquid to generate bubbles, which cause a sudden state change due to expansion and contraction of the volume.
And

The heat acting portion 47 is located above the heat generating portion 48 of the electrothermal converter 42, and has a low heat acting surface 49 as a surface of the heat generating portion 48 which is in contact with the liquid. The heat generating section 48 includes a lower layer 50 provided on the base 43, a heating resistor layer 51 provided on the lower layer 50, and an upper layer 52 provided on the heating resistor layer 51.

On the surface of the heating resistance layer 51, electrodes 53 and 54 for supplying electricity to the layer 51 to generate heat are provided on the surface thereof.
A heat generating portion 48 is formed by a heat generating resistance layer between these electrodes.

The electrode 53 is an electrode common to the heat generating unit of each liquid discharging unit, and the electrode 54 is a selection electrode for selecting the heat generating unit of each liquid discharging unit to generate heat. It is provided along the flow path.

The protective layer 52 includes the heat generating resistance layer 51 in the heat generating portion 48,
In order to protect the used liquid chemically and physically, the heating resistance layer 51 is isolated from the liquid filling the liquid flow path of the liquid discharge section 46, and the short circuit between the electrodes 53 and 54 through the liquid is prevented. It has a function of preventing the occurrence of electric leakage between adjacent electrodes.

The liquid flow paths provided in each of the liquid discharge sections are communicated upstream of each of the liquid discharge sections via a common liquid chamber (not shown) constituting a part of the liquid flow path. The electrodes 53 and 54 connected to the electrothermal converter 42 provided in each liquid discharge unit are protected by the upper layer and pass under the common liquid chamber on the upstream side of the heat acting unit due to the design convenience. It is provided to pass through.

FIG. 27 is a detailed view for explaining the structure of the bubble generating means using a pressure resistance resistor, in which 61 is a heating resistor, 62 is an electrode, 63 is a protective layer, 64 is a power supply device, Heating resistor 61
As material constituting the a useful, for example, a mixture of Tantaru SiO _2, tantalum nitride, nichrome, silver - palladium alloy, silicon semiconductor or hafnium,
Examples include borides of metals such as lanthanum, zirconium, titanium, tantalum, tungsten, molybdenum, niobium, chromium, and vanadium.

Among these materials constituting the heating resistor 61, metal borides can be mentioned as being particularly excellent, and among them, hafnium boride has the most excellent characteristics.
Next are zirconium boride, lanthanum boride, tantalum boride, vanadium boride, and niobium boride.

The heating resistor 61 can be formed using the above-mentioned materials by using a technique such as electron beam evaporation or sputtering. The film thickness of the heating resistor 61 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. , But usually 0.001-5μ
m, preferably 0.01 to 1 μm.

As the material forming the electrode 62, many commonly used electrode materials are effectively used, and specifically,
For example, Al, Ag, Au, Pt, Cu and the like can be cited, and they are provided at a predetermined position in a predetermined size, shape and thickness by a technique such as vapor deposition.

The characteristics required for the protective layer 63, without preventing the heat generated by the heating resistor 61 from being effectively transmitted to the recording liquid,
This means that the heating resistor 61 is protected from the recording liquid. Useful materials for forming the protective layer 63 include, for example, silicon oxide, silicon nitride, magnesium oxide, aluminum oxide, tantalum oxide, zirconium oxide, and the like. Can be formed. Protective layer
The thickness of 63 is usually 0.01 to 10 μm, preferably 0.1 to 5 μm.
μm, and most preferably 0.1 to 3 μm.

In the above-described principle or the bubble jet technology having a heating element structure, the present invention provides an ejection port for ejecting a liquid to form an amorphous droplet, and applying a heat to the liquid to eject the liquid. A liquid ejecting recording apparatus comprising: a liquid ejecting recording head having an electric heat exchanger layer for causing a state change due to pressure and a pair of electrodes electrically connected to the electric heat exchanger layer. The exchanger layer is
The pair of electrodes are formed so that the length in the direction of conduction is longer than the length in the direction perpendicular to the direction of conduction, and have a thermal gradient in the direction of conduction above or below the electrothermal exchanger layer. Or an independent heat radiating structure is formed, and the input energy is made variable in accordance with image information.

FIG. 1 is a structural view of a main part (heating element) of a bubble jet liquid jet recording apparatus according to the present invention, and FIG. 2 is the same as FIG. FIG. 3 is a main part configuration diagram of a bubble jet liquid jet recording apparatus having a heating element having a form shorter than the length in a direction perpendicular to FIG. (A) is a plan view,
(B) is a sectional view taken along the line BB of (a), and FIG.
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, and 17 is an insulating layer.

FIG. 4 shows only the heating element layer of FIG. 1 taken out, and the heating element layer of the present invention has a length L between the direction of conduction and the length W perpendicular to the direction of conduction. L> W. The shape of the heating element layer need not be rectangular. In the case of not being rectangular, as shown in FIG. 5, when the shape of the heating element layer is approximated by a rectangle, the length L ′ between the length in the energizing direction and the length W ′ in the direction perpendicular to the energizing direction is L '>
What is necessary is that the relationship of W 'holds. In the present invention, as shown in FIG.
A radiator 16 is provided on 12.

The radiator 16 is not provided evenly on the entire surface of the heating element layer 12, but as shown in FIG. 1, the area covering the heating element 12 changes from the control electrode 13 side to the ground electrode 14 side. 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. In the present invention, since the heat radiator is formed two-dimensionally as described above, there is an advantage that the heat radiator can be easily and simply manufactured or manufactured. In the case of FIG. 1, 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 function as a ground electrode. Appropriate insulating treatment 17 is performed without contacting the electrode 14. According to the present invention, for a head having a thermal gradient on such a heating element layer,
Further, the input energy to the heating element layer is changed according to the image information. Generally, in bubble jet technology, when air bubbles are generated on a heating element layer by a film boiling phenomenon, it is necessary that the surface temperature on the heating element layer instantaneously reaches a certain temperature or higher. 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. 6 shows the principle.

FIG. 6 shows bubbles generated in the cross section of FIG. 1 by dotted lines. As described above, in the present invention, the heat radiator 16 provided on the heating element layer 12 has a thermal gradient on the heating element layer with respect to the energization direction. 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. 6, the bubbles 18 gradually increase from the small bubbles 1 to 2, 3, and 4.

In order to effectively control the amount of liquid discharged from the discharge port by controlling the amount of input energy, the sensitivity of the amount of movement of the critical point position of bubble generation to changes in the amount of input energy must be sufficiently large. . In the present invention, the length L of the heating element layer 12 in the direction of conduction shown in FIG. 4 is longer than the length W of the heating element layer 12 in the direction perpendicular to the direction of conduction. Thereby, the sensitivity is improved to a required size. FIG. 7 shows this state.

FIG. 7 shows the relationship between the shape of the heating element provided with a heat radiator and the critical point position of bubble generation. FIG. 7 (a) shows FIG. The heating element portion when the length L is longer than the length W in the direction perpendicular thereto,
FIG. 2 (b) shows the heating element portion in FIG. 2, that is, when the length L of the heating layer in the conduction direction is shorter than the length W in the direction perpendicular thereto. In the figure, 1 is a critical point position for bubble generation when the value of the input energy is small, and 2 is a critical point position for bubble generation when the value of the input energy is large.
(A) In the case of the figure, when the value of the input energy is large,
The region exceeding the critical temperature greatly increases toward the discharge port side from the region exceeding the critical temperature when the value of the input energy is small and increases. On the other hand, in the case of the diagram (b), the area of the region exceeding the critical temperature when the value of the input energy is large is slightly larger than the area of the region exceeding the critical temperature when the value of the input energy is small. And the amount of movement of the critical point position toward the discharge port is also small. In order to prevent heat accumulation in the liquid jet recording head and to enable high-density arrangement of the ejection ports, it is desirable that the area of the heating element layer be small.
> W has a greater sensitivity to the change in the input energy amount of the movement amount of the above-described critical point position of bubble generation than the case of L ≦ W. The area of the body layer can be reduced.

FIG. 8 shows the relationship between the input energy and the size of the generated bubble, and FIG. 9 shows the relationship between the generated bubble and the amount of ink ejected. The solid line is a value in the bubble jet liquid jet recording apparatus of the present invention, and the dashed line is a value in the bubble jet liquid jet recording apparatus in the form of L <W. As the input energy, either the pulse voltage or the pulse width may be changed, but it is desirable to change the pulse voltage in order to instantaneously generate bubbles using the film boiling phenomenon. However, there is no practical problem as long as the pulse width is changed within a range up to about 30 μsec.

FIG. 10 is a view for explaining another embodiment of the present invention. In this case, a heat radiator 16 is formed below the heat generating layer 12. FIG. 11 shows still another embodiment. In this case, a heat radiator 16 is formed on the protective layer 15. Fig. 12,
FIG. 13 is a modified embodiment of the pattern of the heat radiator 16, and the stepwise shape as shown in FIG. 12 is advantageous in that the cost for manufacturing a photomask is reduced. On the other hand, when radiators are formed on both sides as shown in FIG. 13, there is an advantage that the generated bubbles have better symmetry and are stable.

Although the embodiments of the present invention have been described briefly, the description has been omitted in consideration of the complexity of the drawings. For example, FIG. 1, FIG. 2, FIG. 3, FIG.
In the sectional views (FIG. 10B) of FIGS. 10 and 11, the electrodes are sticky, but it is preferable that the electrodes are not directly contacted with the ink by a suitable protective film (polyimide or the like). Similarly, if a material (for example, Al) that is corroded by ink is used for the heat radiator, a protective film should be provided. 1 and 2
FIG. 3, FIG. 10, FIG. 10, FIG. 11, and FIG.
In FIG. 12 and FIGS. 12 and 13, the protective film on the heating element layer is omitted, but this is also to avoid complicating the drawing, and the protective film actually exists.

Next, a specific method of manufacturing the liquid jet recording head shown in FIG. 1 will be described. First, a silicon wafer is thermally oxidized to grow a SiO ₂ film on its surface to a thickness of 2 μm to form a heat storage layer 11.
And Next, as the heating element layer 12, HfB ₂ is sputtered at 2200 °. Next, as the heat radiator 16, Al was deposited by 10,000 °. Next, Au was vapor-deposited at 8000 ° as electrodes 13 and 14.
At this time, the insulating layer 17 should be
Previously formed SiO ₂ as. Next, the protective film 15 of the heating element layer
The SiO ₂ was 9000Å sputtering as. Furthermore, Ta was sputtered thereon at 3000 ° as a cavitation-resistant layer. During the formation of each of these films, a well-known photolithography technique and a photo-etching technique are used, and the final pattern of the heating element is a rectangle of 24 μm × 80 μm. The electrode width is 24μ in the width direction of the heating element pattern.
m.

FIG. 14 shows another embodiment of the present invention. Thus, the first
In the embodiment shown in the figure, the radiator 16 is provided with the insulating layer 17 of SiO ₂ so as not to contact the ground electrode 14,
In the embodiment shown in FIG. 14, there is no insulating layer of SiO ₂ , and the radiator 16 is in contact with the ground electrode 14. Therefore, the radiator 16
Also serves as a ground electrode, in other words, the heat-generating portion of the heat-generating body layer is not rectangular, but becomes a portion where the heat-radiating body is not applied in FIG. 14, that is, a right-angled triangular portion in FIG. 14 (a), The heating element layer itself has a thermal gradient. In this case, the above-described length L of the heating element layer in the energization direction corresponds to the length of the side in the energization direction of the right triangular heating portion. In this case, both the heat gradient of the heat radiator and the heat gradient of the heat generating layer act.

Further, in the description of the manufacturing method in the case of FIG. 1, it is shown that the heat radiator and the electrode (earth electrode) are manufactured separately.
In the case of FIG. 14, they may be manufactured simultaneously (integrally).

FIG. 15 shows still another embodiment, for example, 16
A heat radiator is formed by applying the present invention to a heat generating substrate having an electrode laminated structure in order to enable a high-density arrangement of / mm or more. A method for manufacturing a heating element substrate having an electrode laminated structure will be briefly described.

FIG. 16 is a cross-sectional view for explaining another embodiment of the present invention, in which 10 is a substrate, 12 is a heating resistor layer, and 13 is a first embodiment.
, 14 is the second electrode, 15 is the protective layer (ink resistant), 17
Is an insulating layer, part A of the first electrode 13 is a part from which a lead wire is taken out, and part B is a part to which a heating resistor is connected.

FIGS. 17 (a) to 17 (e) are views showing a procedure for obtaining the configuration shown in FIG. 16. First, the first electrode 13 is formed on the substrate 10 (FIG. 17 ( a)), an insulating layer 17 is provided on the electrode 13 except for at least a portion A from which a lead wire is taken out and a portion B to which a heating resistor layer 12 described later is connected (FIG. 17 (b)). . Next, the heating resistor layer 12 is provided (FIG. 17C), and the second electrode 14 faces the portion B of the heating resistor layer 12 connected to the first electrode 13. They are connected at positions (FIG. 17 (d)).
Finally, a protective film 15 is formed to protect the heating resistor layer 12 from ink, and is completed (FIG. 17 (e)). In addition,
In addition, an electrode protection layer or an anti-cavitation protection film is provided if necessary. However, the description is omitted here for simplification. FIG. 15 is a plan view showing an example in which the heat radiator 16 of the present invention is provided to the electrode-laminated heating element substrate manufactured by the above-described process.

18 (a) to 18 (g) are views showing a manufacturing process of the heating element substrate according to the present invention, and FIG. 19 is a cross-sectional view taken along the line AA of the heating element substrate completed in FIG. 18 (g). is there. In the figure, 91 is a heating element (HfB ₂ ), 92 is a first electrode (Al), 93 is an insulating layer (Si)
O ₂ ), 94 is a second electrode (Al), 95 is a heat insulating layer (SiO ₂ ), 96
Denotes an anti-cavitation layer (Ta), 97 denotes an electrode protection layer (photonice), and 98 denotes a bonding pad. The hatched portions are the formation patterns in each step. 11A, a heating element 91 is formed on a Si wafer having a SiO ₂ film formed on the surface by thermal oxidation or the like. Here, HfB ₂ was formed by 3000 ° sputtering as a heating element material. (B) As the first electrode
Al92 was formed by 10,000 ° sputtering.
(C) SiO ₂ was formed as the insulating layer 93 by 8000 ° sputtering. When this pattern is formed, an insulating layer is not attached to a portion connected to a second electrode described later and a portion of the bonding pad. (D) Al94 was formed as the second electrode by sputtering at 10,000 °. The second electrode also serves as a heat dissipation structure. As is clear from the figure, the area occupied by the heat dissipation element in the portion above the heating element via the insulating layer is continuous so as to have a heat gradient in the direction of current flow. Has changed to Note that Al is one of the most suitable materials for the heat radiation structure because of its excellent electrode material and good thermal conductivity. (E) Next, SiO ₂ was formed as the thermal insulating layer 95 by 5000 ° sputtering. This is for thermally separating the cavitation-resistant layer described later and the above-mentioned heat dissipation structure so that the heat dissipation structure exerts its function better. (F) Ta was formed as the anti-cavitation layer 96 by 3000 ° sputtering. This is to absorb the physical impact force when the generated bubbles disappear, protect the heating element from damage, and extend the life. (G) As the electrode protection layer 97,
Photo Nice (manufactured by Toray Industries, Inc.) was formed to 12,000 mm.

20 (a) to 20 (g) are views showing another embodiment of the manufacturing process of the heating element substrate according to the present invention, and FIG. 21 is a drawing showing the B-B of the heating element substrate completed in FIG. 20 (g). It is B sectional drawing. In the figure, 101 is a first electrode (Al), 102 is an insulating layer (Si)
O ₂ ), 103 is a heating element (HfB ₂ ), 104 is a second electrode (Al), 10
5 is a heating element protection layer (SiO ₂ ), 106 is an anti-cavitation layer (Ta), 107 is an electrode protection layer (photonice), and 108 is a bonding pad. The hatched portions are the formation patterns in each step. (A) Al was formed as the first electrode 101 on a Si wafer having a SiO ₂ film formed thereon by thermal oxidation or the like by 10,000 ° sputtering. The first electrode also serves as a heat dissipation structure, and as is apparent from the drawing, the pattern of the portion where the heating element formed via the insulating layer described later is laminated is formed in the direction in which the heating element is energized. The area occupied by the heat is continuously changed so as to have a thermal gradient due to heat radiation.
(B) As the insulating layer 102, SiO ₂ was formed by 8000 ° sputtering. When forming this pattern, an insulating layer is not attached to a portion connected to a second electrode described later and a portion of the bonding pad. (C) HfB ₂ was formed as the heating element 103 by 3000 ° sputtering. (D) Al was formed as the second electrode 104 by sputtering at 10,000 °. (E) Heating element protective layer
As 105, SiO ₂ was formed by 10,000 ° sputtering. This is mainly to prevent the heating element from being chemically corroded by the ink, and is formed so as to reduce defects such as pinholes. That is, it is formed as thick as possible. On the other hand, from the viewpoint of heat conduction efficiency to the ink or thermal stress, it is desirable to form the ink as thin as possible.
000Å has been adopted. (F) Anti-cavitation layer 106
Was formed by 3000 ° sputtering. This is to absorb the physical impact force when the generated bubbles disappear, protect the heating element from damage, and extend the life. (G) Photonice (manufactured by Toray Industries, Inc.) was formed as an electrode protection layer 107 by 12,000 Å. Although the description is omitted, in each of the embodiments described above with reference to FIGS. 18 to 21, the pattern is formed by forming each layer by sputtering and then applying a positive photoresist OFPR (Tokyo Ohka Co., Ltd.) ), And each pattern was formed by etching.

The heating element substrate according to the present invention thus formed has a polyimide electrode protection layer as described above, if necessary.
The thickness is 5 to 5 μm. A lid substrate shown in FIG. 24A is joined to the heating element substrate of the present invention thus completed to complete a head. When the input pulse voltage is changed from 18 to 40 V using this head, the size of the bubble (the length of the bubble on the heating element pattern) can be changed from 15 to 110 μm. change,
The pixel diameter on the paper could be changed from 50 μm to 120 μm. The pulse width at this time is 6 μsec.

Effects As is clear from the above description, according to the present invention, a heat sink can be formed two-dimensionally using thin film forming technology, photolithography technology, photo etching technology, etc., so that manufacturing is easy and high accuracy. it can.

Since the electrothermal transducer layer has an elongated shape, the sensitivity of the volume of the bubble and the position where the bubble is generated to the input energy change is increased, so that the ability to control the ink ejection amount by the input energy is increased.

Also, since the electric heat exchanger layer has an elongated shape, the directivity of bubble growth in the direction of the discharge port is increased, so that the ink discharge force is improved.

The electrothermal transducer layer according to the embodiment of the present invention has the same length as the electrothermal exchanger layer in which the length L in the direction of conduction and the length W in the direction perpendicular to the direction of conduction is L ≦ W. Since the ink ejection amount control ability and the ink ejection force are large even in the area, it is advantageous in preventing heat storage in the liquid jet recording head and in arranging ejection ports at high density.

Further, in addition to the above, by providing one of the electrodes with a function of a heat dissipation structure, the layer structure of the heating element portion is simplified, thereby improving the efficiency of heat transfer to the ink or thermal stress. Deterioration of the heating element due to the fact that disconnection is extremely reduced, the life of the heating element is lengthened, the yield in the manufacturing process is improved, and the manufacturing cost is reduced due to simplification. There are also significant advantages.

[Brief description of the drawings]

FIGS. 1 and 2 show the structure of a heat generating portion of a bubble jet liquid jet recording apparatus according to the present invention, respectively. FIG. 3 shows a heating element of a bubble jet liquid jet recording apparatus which does not perform normal gradation recording. FIG. 4 is a diagram showing a shape of a heating element layer, FIG. 5 is a diagram showing an example of a deformed shape of the heating element layer, and FIG. 6 is a diagram illustrating a principle of changing a size of bubble generation. FIG. 7 is a diagram showing the relationship between the shape of the heating element and the critical position of bubble generation, FIG. 8 is a diagram showing the relationship between input energy and bubble size, and FIG. FIGS. 10 and 11 show the relationship between the size of bubbles and the amount of ejected ink, FIGS. 10 and 11 show another embodiment of the present invention, and FIGS. 12 and 13 show the deformation of the radiator pattern, respectively. FIG. 14 is a diagram illustrating an example, FIG. 14 is a diagram for explaining another embodiment of the present invention, and FIGS. FIGS. 18 and 19 are diagrams showing a manufacturing process of a heating element substrate of the present invention, and FIGS. 20 and 21 are diagrams of a heating element substrate of the present invention. FIG. 22 shows another embodiment of the manufacturing process, FIG.
The figure for explaining the operation of the bubble jet head as an example of the ink jet head to which the present invention is applied, FIG.
FIG. 23 is a perspective view showing an example of a bubble jet head, and FIG.
FIG. 24 is an exploded perspective view, FIG. 25 is a view of the lid substrate viewed from the back surface, FIG. 26 is a diagram for explaining the details of the bubble jet recording head, and FIG. FIGS. 26 to 35 are views for explaining the structure of the bubble generating means,
FIGS. 28 to 30 each show a configuration of a conventional heating element layer. FIGS. 28 to 30 show examples in which the thickness of a protective layer, a heat storage layer, or a heating element layer is gradually changed, and FIGS. The figure shows an example in which the pattern width of the heating element layer is gradually changed. 10 ... substrate, 11 ... heat storage layer, 12 ... heating element layer, 13 ... control electrode, 14 ... earth electrode, 15 ... protective layer, 16 ... heat radiator, 17 ... insulating layer, 18 ... … Generated bubbles.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshio Watanabe 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Masafumi Kamonaga 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Masaki Horiya 1-3-6 Nakamagome, Ota-ku, Tokyo, Japan Ricoh Co., Ltd. (56) References JP-A-55-132258 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) B41J 2/05 B41J 2/205

Claims (2)

(57) [Claims] 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; In a liquid jet recording apparatus including a liquid jet recording head having a pair of electrodes electrically connected to a heat conversion element layer, the length of the electrothermal conversion layer is perpendicular to the current direction. The heat radiation structure having a two-dimensional planar structure is formed on the electrothermal transducer layer so as to have a thermal gradient in the direction of electric current, and the input energy is reduced in accordance with image information. A liquid jet recording apparatus characterized by being variable. 2. An ejection port for ejecting liquid to form flying droplets, an electrothermal transducer layer for causing the liquid to undergo a state change due to heat in order to eject the liquid, and In a liquid jet recording apparatus using a liquid jet recording head having a pair of electrodes electrically connected to a heat conversion layer, the length of the electrothermal conversion layer is perpendicular to the current direction. The heat radiation structure having a two-dimensional planar structure is formed below the electrothermal transducer layer so as to have a thermal gradient in the direction of current flow, and the input energy is reduced in accordance with image information. A liquid jet recording apparatus characterized by being variable.