JPH05169678A - Liquid jet recorder and recording method - Google Patents

Abstract

PURPOSE:To obtain a means for changing a printing density or conducting gradation recording in an ink jet recording in which ink is changed in phase by heat and delivered out of a fine orifice for conducting recording. CONSTITUTION:An ink container 33 or an ink cartridge as an ink supply means is appropriately changed in height with respect to a recording head H, whereby the position of an ink meniscus in an orifice 24 is moved forward and backward, and a mass of ink to be delivered by a bubble formed by a heating element 29 is controlled. In this manner, the recording head H functions so as to handle a multi-valued recording image other than a binarized recording image which can be formed by a basic delivery ink amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid jet recording apparatus and recording method.

[0002]

2. Description of the Related Art The non-impact recording method has recently been drawing attention because noise during recording is extremely small to a negligible level. Among the recording methods, high-speed recording is possible, and the so-called ink jet recording method, which enables recording on plain paper without requiring a special fixing process, is an extremely powerful recording method. Various methods have been proposed so far, some of which have been improved and commercialized, and some of which are still being put into practical use.

In such an ink jet recording method, small droplets of a recording liquid, so-called ink, are ejected and adhered to a recording member (recording paper) for recording, and this recording liquid is used. The method is roughly classified into several methods according to the method of generating droplets and the control method of controlling the flight direction of the generated droplets of the recording liquid.

First, the first method is, for example, USP306.
The method disclosed in Japanese Patent No. 0429 (Tele t
type system). This is to electrostatically absorb the generation of the recording liquid droplets, and to control the electric field of the generated recording liquid droplets according to the recording signal to selectively deposit the recording liquid droplets on the recording member. Is recorded. More specifically, by applying an electric field between the nozzle and the accelerating electrode, uniformly charged droplets of the recording liquid are ejected from the nozzle, and the ejected droplets of the recording liquid are responded to the recording signal. Recording is performed by flying between xy deflection electrodes configured to be electrically controllable, and selectively depositing a small droplet of the recording liquid on the recording member according to a change in the electric field strength.

The second method is, for example, USP359627.
5 and US Pat. No. 3,298,030, etc., is a method (Sweet method), which generates small droplets of a recording liquid whose charge amount is controlled by a continuous vibration generation method, and Recording is performed on the recording member by causing a controlled droplet of the recording liquid to fly between the deflection electrodes to which a uniform electric field is applied.

Specifically, before the orifice (ejection port) in the recording head provided with the piezoelectric vibrating element,
Charging electrodes configured to apply a recording signal are arranged apart from each other by a predetermined distance, an electric signal having a constant frequency is applied to the piezoelectric vibrating element to mechanically vibrate the piezoelectric vibrating element, and the piezoelectric element is ejected from the ejection port. Eject small droplets of recording liquid. At this time, electric charges are electrostatically induced in the small droplets of the recording liquid ejected by the charging electrodes, and the small droplets of the recording liquid are charged with an amount of electric charge according to the recording signal. When the droplets of the recording liquid of which the charge amount is controlled fly between the deflection electrodes to which a constant electric field is uniformly applied, the droplets are deflected according to the added charge amount and carry the recording signal. Only the small droplets can adhere to the recording member.

The third method is, for example, USP341516.
According to the method disclosed in Japanese Patent No. 3 (Hertz method), an electric field is applied between a nozzle and a ring-shaped charging electrode, and small droplets of a recording liquid are generated and atomized by a continuous vibration generation method for recording. It is a method. That is, in this method, the atomization state of the small droplets of the recording liquid is controlled by modulating the electric field strength applied between the nozzle and the charging electrode according to the recording signal, and the gradation of the recorded image is output to produce the recorded image. is there.

A fourth method is, for example, USP374712.
Method disclosed in specification No. 0 (Stemme method)
The principle of this method is fundamentally different from the above three methods. That is, in all of the three methods, the droplets of the recording liquid ejected from the nozzles are electrically controlled during the flight, and the droplets of the recording liquid that carry the recording signal are selectively recorded. On the other hand, the recording is performed by adhering the recording liquid onto the upper surface, whereas in this method, a small droplet of the recording liquid is ejected and ejected from an ejection port according to a recording signal to perform recording. In other words, this system applies an electrical recording signal to a piezoelectric vibration element attached to a recording head having a discharge port for discharging a small droplet of recording liquid, and applies this electrical recording signal to the mechanical vibration of the piezoelectric vibration element. The recording is performed by changing to the mechanical vibration and ejecting and ejecting a small droplet of the recording liquid from the ejection port according to the mechanical vibration and adhering it onto the recording member.

These four conventional methods have their respective characteristics, but on the other hand, they also have a point to be solved. That is, in the first to third methods, the direct energy for generating the recording liquid droplets is electrical energy, and the deflection control of the recording liquid droplets is also electric field control. Therefore, the first method is simple in configuration, but requires a high voltage to generate small droplets of the recording liquid, and it is difficult to form the recording head with multiple nozzles. Therefore, the first method is not suitable for high-speed recording. is there.

The second method is suitable for high-speed recording because the recording head can have multiple nozzles, but has a complicated structure, and it is difficult and difficult to electrically control small droplets of the recording liquid. There is a problem that satellite dots are easily formed on the member. The third method has a feature that an image excellent in gradation can be recorded by atomizing the small droplets of the recording liquid, but on the other hand, it is difficult to control the atomized state, and fog is generated in the recorded image. However, there are various problems that it is difficult to make the recording head multi-nozzle and it is not suitable for high-speed recording.

The fourth method has many advantages over the first to third methods. That is, since the configuration is simple and the recording liquid is ejected from the ejection ports of the nozzles on-demand to perform recording, it is suitable for ejecting and ejecting as in the first to third methods. Of these, it is not necessary to collect the small droplets that were not required for image recording, and there is no need to use a conductive recording liquid as in the first and second methods, and it is a substance of the recording liquid. It has great advantages such as a high degree of freedom. However,
On the other hand, there is a problem in processing the recording head,
It is difficult to make the recording head multi-nozzle because it is extremely difficult to miniaturize the piezoelectric vibrating element having a desired resonance frequency, and the mechanical energy of mechanical vibration of the piezoelectric vibrating element causes a small amount of recording liquid. Since the droplets are ejected and ejected, they are not suitable for high-speed recording.

As described above, in the conventional liquid jet recording method,
There are merits and demerits in terms of configuration, high-speed recording, multi-nozzle of recording head, generation of satellite dots, fog of recorded image, etc., and there is a restriction that it can be applied only to applications that take advantage of that advantage. ..

However, such an inconvenience can be almost eliminated by adopting the ink jet recording method as the liquid jet recording method previously proposed by the present applicant. As one of such ink jet recording systems, there is Japanese Patent Publication No. 56-9429. In this method, the ink in the liquid chamber is heated to generate bubbles to cause a pressure increase in the ink, the ink is ejected from a fine capillary nozzle, and recording is performed on a recording member. After that, many inventions were made to improve this principle.

As a similar recording system, Japanese Patent Publication No. 61-59
There is a technique disclosed in Japanese Patent No. 914. In this technique, a part of the recording liquid is heated to cause film boiling in a liquid path communicating with the discharging port for discharging the recording liquid in a predetermined direction, and thereby the recording liquid discharged from the discharging port is discharged. Droplets are ejected and deposited on the recording member. Specifically, in the thermal action portion provided in the nozzle-shaped liquid path portion, the recording liquid undergoes a rapid state change, By the action force based on the state change, the small droplet of the recording liquid is ejected and ejected from the ejection port.

The principle of ink ejection by the bubble jet will be described with reference to FIG. (A)
Is a steady state, and the surface tension of the ink 10 and the external pressure are in equilibrium at the orifice 4. (B) shows a state in which the heating element 9 as a heater is heated, the surface temperature of the heating element 9 rises sharply, and is heated until the boiling phenomenon occurs in the adjacent ink layer, and the minute bubbles 11 are scattered.

(C) shows a state in which the adjacent ink layer that has been rapidly heated on the entire surface of the heating element 9 is instantly vaporized to form a boiling film, and the bubble 11 has grown. At this time, the pressure in the nozzle rises as much as the bubbles grow, the balance with the external pressure on the orifice surface is lost, and the ink column starts to grow from the orifice 4. (D) shows a state in which the bubble 11 has grown to the maximum, and the ink 10 corresponding to the volume of the bubble is pushed out from the orifice surface. At this time, no current is flowing in the heating element 9, and the surface temperature of the heating element 9 is decreasing. The maximum value of the volume of the bubble 11 is slightly delayed from the timing of applying the electric pulse.

(E) shows a state in which the bubble 11 is cooled by ink or the like and starts to contract. At the front end of the ink column, the ink column moves forward while maintaining the pushing speed, and at the rear end, ink contracts back from the orifice surface into the nozzle due to the decrease in the nozzle internal pressure due to the contraction of the bubbles 11, and the ink column is constricted. Has occurred. In (f), the bubble 11 is further contracted,
The ink is in contact with the surface of the heating element, and the surface of the heating element is further rapidly cooled. On the orifice surface, the external pressure is higher than the internal pressure of the nozzle, so a large meniscus has entered the nozzle. The tip of the ink column becomes a droplet and flies toward the recording paper at a speed of 5 to 10 m / sec.

(G) is a process in which the ink is supplied to the orifice again by the capillary phenomenon and returns to the state of (a),
The bubbles have disappeared completely. FIG. 13 is a cross-sectional view of the main part of the bubble jet type ink jet recording head described above, which is generally called EDGE SHOOTER,
On the other hand, the inkjet recording head shown in FIG. 14 is called SIDE SHOTER. The operating principle of the ink jet recording head shown in FIG. 14 is shown in FIG. 15. As in the description of FIG. 12, the state of (a) is changed to the state of (e) and then the state of (a) is changed. It returns, and in the meantime, the droplet 12 is ejected. In the figure, 1 is a lid substrate, 2 is a heating element substrate, 4 is an orifice, and 5
Is a flow path, 9 is a heating element (heater), 10 is ink, 11 is a bubble, and 12 is a flying ink liquid.

The feature of this system is that it is shown in FIGS.
This is the point where the film boiling phenomenon is used in the process of-(d) or FIGS. 15 (b)-(c). In order to be able to be applied as a recording means, it depends on how to perform control for regularly generating and eliminating film bubbles.

The film boiling phenomenon occurs in the following two cases. Immerse an object heated to a high temperature in the liquid surface. Suddenly raise the surface temperature of the object that comes into contact with the liquid. In order to reproduce the film boiling phenomenon on the heater, the method of is used. FIG. 16 shows the pulse width applied to the heater and how bubbles are generated. When a very short pulse of about 10 μs or less is given, the heater is rapidly heated, and the ink reaches the overheat limit before the pre-existing foam nuclei are activated, and a clean film bubble is obtained. This foam is calculated to be 15 kg / cm
Adiabatic expansion with a certain internal pressure pushes ink out of the nozzle. The heating is stopped when the bubbles become maximum, and the vapor bubbles deprived of the heat disappear by themselves.

When heating is gradually performed, normal boiling starts from the foam nuclei existing on the heater surface, and unspecified bubbles and fixed bubbles are generated as shown in the figure. Repeatability, bubble size and disappearance. Cannot be controlled. By realizing such film boiling on the heater surface, the size of bubbles is uniform and stable (bubbles of the same size can always be formed at the same timing.) Little heat loss to ink (ink is not heated much) Therefore, no cooling means is required.)
When the bubble reaches the maximum volume, the ink around the bubble has already cooled, so the bubble contracts rapidly (frequency response is good, and bubble generation and disappearance are repeated at high speed). An ideal means can be obtained as a driving force for ejecting a demand type inkjet.

Further, in this method, the size of the bubble influences the ejection characteristic, and as is clear from the principle, the fact that the size of the bubble does not depend on the voltage can bring about such characteristic. There is. The size of the bubble depends on the size of the heater and the structure of the nozzle. Therefore, once the design is determined, it is possible to obtain stable dots, which is optimal as a digital type recording means. That is, this method is a so-called binary recording technique in which the liquid droplets are ejected, but are not ejected.

However, in order to satisfy the increasing demands of printer users in recent years, simple binary recording is not enough, print density can be changed, or high-definition pictorial color printing is possible. It is required to be able to record.

[0024]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an ink jet which causes a change in state of ink due to heat and ejects the ink from a fine orifice for recording. An object of the present invention is to provide an apparatus and method capable of changing print density or performing gradation recording in recording.

[0025]

To achieve the above object, the present invention provides, as a liquid jet recording apparatus, an orifice for ejecting ink, a thermal energy acting portion provided in a flow path leading to the orifice, and A liquid ejecting recording apparatus, comprising a liquid chamber containing an orifice and a flow path for holding ink, and a means for supplying the ink to the liquid chamber, wherein the ink is ejected as droplets onto a recording medium to perform recording, It is characterized in that the positions of the orifice side and the means for supplying the ink to the liquid chamber in the height direction are relatively variable.

The present invention provides, as a liquid jet recording method, an orifice for ejecting ink, a thermal energy acting portion provided in a flow path leading to the orifice, a liquid chamber for holding ink including the orifice and the flow path, In a liquid jet recording apparatus having a means for supplying ink to the liquid chamber and ejecting the ink as droplets onto a recording medium to perform recording, the position of the ink meniscus at the orifice is changed to perform recording. It is what

The present invention also provides, as a liquid jet recording method, an orifice for ejecting ink, a thermal energy acting portion provided in a flow path leading to the orifice, and a liquid chamber for holding ink including the orifice and the flow path. And a means for supplying ink to the liquid chamber, wherein the ink is ejected as droplets onto the recording medium to perform recording, and
The recording is performed by changing the position of the ink meniscus in the orifice and changing the input energy to the thermal energy acting portion.

Furthermore, the present invention provides, as a liquid jet recording method, an orifice for ejecting ink, a thermal energy acting portion provided in a flow path leading to the orifice, and a liquid chamber for holding ink including the orifice and the flow path. And a means for supplying ink to the liquid chamber, wherein the ink is ejected as droplets onto the recording medium to perform recording, and
When the image information is binary information, a substantially constant energy is input to the thermal energy acting portion, ink having a substantially constant mass is ejected from the orifice, and when the image information is multivalued information, the binary information It is characterized in that the ink meniscus of the orifice is retracted more than in the case, the energy smaller than the substantially constant energy is input once to a plurality of times, and the ink discharge amount is changed according to the input frequency.

[0029]

With the configuration of the present invention, the position of the ink meniscus at the orifice can be moved back and forth by appropriately changing the height of the ink container or the ink cartridge as the ink supply means with respect to the recording head. It is possible to control the mass of the ejected ink to be ejected by the formed bubbles and to act as a recording head that can deal with multi-valued recording images other than the binary recording image, which is the basic amount of ejected ink. Also, by changing the input energy applied to the ink meniscus and the heating element,
Supports a wide range of multi-value recorded images.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 7 is a perspective view showing an example of a bubble jet head to which the present invention is applied, and FIG. 8 is a lid substrate (FIG. 8A) and a heating element substrate (FIG. 8) that constitute the recording head shown in FIG. 8 (b)) is an exploded perspective view, and FIG. 9 is FIG. 8 (a).
FIG. 6 is a perspective view of the lid substrate shown in FIG. 2 in the figure
Reference numeral 1 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. , 29 are heating elements (heaters).

The present invention is applied to a recording head relating to such bubble jet type liquid jet recording. In the present invention, the lid substrate 21 is integrally molded with resin and manufactured. As the resin material used, polysulfone, polyether sulfone, polyphenylene oxide, polypropylene or the like, which has excellent ink resistance, is used. Among them, "mel" which has good fluidity for molding
It is preferable to use a material having a “t flowrate” of 10 g / 10 min or more. Although a commercially available injection molding machine is used as the molding machine, a molding machine having an injection pressure of 2000 kg / cm ² or more is desirable in order to transfer a fine shape with high accuracy. Further, in order to enhance the fluidity of the resin, the cylinder temperature is heated to 400 ° C. or higher. As the mold, a mold having a shape that forms a pair with the lid substrate 21 shown in FIG. 9 is used. Further, in order to improve transferability, a heater, a heat medium, etc. are provided in the mold so that the material can be heated to a temperature higher than the thermal deformation temperature of the mold. It is also effective to reduce the pressure of the resin-filled portion of the mold with a vacuum pump or the like to improve transferability.

FIG. 10 shows an embodiment for explaining the construction of the main part of the above-mentioned liquid jet recording head. (A) is a detailed front view of the bubble jet head as seen from the orifice side, and (b) is (a). 3 is a partial sectional view taken along the alternate long and short dash line xx in FIG. The structure of the recording head H shown in this drawing is a substrate 43 having an electrothermal converter 42 provided on the back surface.
It is formed by bonding it so as to cover a grooved plate 44 having a predetermined number of grooves with a predetermined linear density and a predetermined width and depth, and liquid is applied to the end of the recording head H. A liquid discharge portion 46 including an orifice 45 for flying is formed.

In the liquid discharge part 46, the heat energy generated from the orifice 45 and the electrothermal converter 42 acts on the liquid to generate bubbles, which causes a rapid state change due to expansion and contraction of the volume. And an action portion 47. The heat acting part 47 is the heat generating part 4 of the electrothermal converter 42.
The heat acting surface 49, which is located on the upper part of 8 and is in contact with the liquid of the heat generating portion 48, is the lower surface thereof. Heat generation part 4
Reference numeral 8 denotes a lower layer 50 provided on the base body 43, and the lower layer 5
0, and a protective layer 52 which is an upper layer provided on the heating resistance layer 51.

The heating resistance layer 51 is provided with electrodes 53 and 54 for energizing the heating layer 51 to generate heat, and a heat generating portion is provided between these electrodes by the heating resistance layer 51. 48 are formed. The electrode 53 is an electrode common to the heat generating portion 48 of each liquid ejecting portion 46, and the electrode 54 is a selection electrode for selecting the heat generating portion 48 of each liquid ejecting portion 46 to generate heat. It is provided along the liquid flow path of the discharge part 46.

The protective layer 52 fills the heat generation resistance layer 51 and the liquid flow path of the liquid discharge part 46 in order to protect the heat generation resistance layer 51 in the heat generation part 48 chemically and physically from the liquid used. It has the role of isolating the existing liquid, preventing a short circuit between the electrodes 53 and 54 through the liquid, and further preventing electrical leakage between adjacent electrodes. The liquid flow path provided in each liquid discharger 46 constitutes a part of the liquid flow path upstream of each liquid discharger, and
Communication is performed via a liquid passage chamber (not shown). The electrode 5 connected to the electrothermal converter 42 provided in each liquid discharger
3, 54 are protected by the protective layer 52, which is the upper layer, on the upstream side of the heat acting portion, due to the design.
It is provided so as to pass under the common liquid chamber.

FIG. 11 is a detailed view for explaining the structure of the bubble generating portion using a heating resistor, in which 61 is a heating resistor, 62 is an electrode, 63 is a protective layer, and 64 is a power supply device. Shows. As a material forming the heating resistor 61,
Useful, for example, a mixture of tantalum -SiO _2, tantalum nitride, nichrome, silver - palladium alloy, silicon semiconductor or hafnium, lanthanum, zirconium, titanium, tantalum, tungsten, molybdenum, niobium, chromium, vanadium, etc. Examples include metal borides.

Among the materials composing these heating resistors 61, metal borides can be mentioned as particularly excellent ones. Among them, hafnium boride has the most excellent characteristics, and then, The order is 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 the area, the material, the shape and size of the heat acting portion, and the actual power consumption so that the heat generation amount per unit time becomes a desired value. In general, it is 0.001 to 5 μm, preferably 0.01 to 1 μm.
It is said that.

As the material for the electrode 62, many of the commonly used electrode materials can be effectively used.
Specifically, for example, Al, Ag, Au, Pt, Cu, and the like are used, and these are provided in a predetermined position, with a predetermined size, shape, and thickness by means such as vapor deposition.

The characteristic required for the protective layer 63 is that it does not prevent the heat generated by the heating resistor 61 from being effectively transferred to the recording liquid, and protects the heating resistor 61 from the recording liquid. is there. Examples of useful materials for forming the protective layer 63 include silicon oxide, silicon nitride, magnesium oxide, aluminum oxide, tantalum oxide, zirconium oxide, and the like. These can be formed using a technique such as electron beam evaporation or sputtering. The thickness of the protective layer 63 is usually 0.01 to
10 μm, preferably 0.1-5 μm, optimally 0.1
It is desirable that the thickness is formed to be about 3 μm.

FIG. 1 shows the relationship between the portion of the recording head and the ink supply means in order to explain the constitution and function of the present invention. As described above, the recording head in the liquid jet recording unit of the present invention is connected to the recording liquid inlet 23, and ink is supplied to the liquid chamber 26, the flow path 25, and the orifice 24, and the liquid chamber 26 is supplied with the ink. Is the pipe 34
An ink container 33 as an ink supply means for accommodating the ink 35 is connected via the. As is clear from this figure, the flow path 25 and the orifice 2 in the recording head H are
4 and the ink container 33 are provided with the head difference of the ink column having the height h. Normally, the static pressure due to the head difference of this height h and the ink meniscus holding force due to the fluid resistance in the flow path 25 and the orifice 24 and the surface tension of the orifice 24 are balanced, and the ink is transferred to the orifice 24.
It doesn't run out of.

In the present invention, as shown by the arrow A in the figure, the height of the ink supply means 33 can be adjusted to be variable. In this way, the ink container 3 as the ink supply means is provided to the side of the flow path 25 and the orifice 24.
By making the height of 3 variable, the position of the ink meniscus of the orifice 24 in the recording head H of the present invention can be easily changed. The ink supply means 33 can be configured to be located higher than the recording head, and the position of the ink supply means 33 can be set to the recording head H.
By setting the position lower than that, it is possible to retract the ink meniscus at the orifice 24 toward the liquid chamber 26 side.

2A and 2B, the orifice 24 is shown.
The case where the positions of the ink meniscus in are different is illustrated. In (a), the ink meniscus is the orifice 24a.
Shows a case where the ink meniscus is drawn in relatively deeply, and (b) shows a case where the ink meniscus is not drawn so much in the orifice 24b.

In the recording head of the liquid jet recording means in the present invention, when the input energy is applied to the heating element 29,
Bubbles are generated at a position near the heating element 29, and ink is ejected from the orifice 24 by the pressure of the generated bubbles. Therefore, the ink ejected by one input energy is the ink located in the region of the orifice 24 from the region of the heating element 29. Therefore, the magnitude of the mass of the ejected ink depends on the position of the ink meniscus of the orifice 24,
It depends on the shape.

By the way, for example, in a printer used for a word processor or the like, there are many cases where it is desired to make a print character thicker than usual and emphasize it. However, the conventional printer cannot meet such a demand because it is a technique corresponding to binary recording as described above. If bold characters are printed, it can be realized by striking the print twice. However, this requires twice the time required for printing, which is not a practical advantage.

However, by changing the position of the ink meniscus as in the present invention, it is possible to print normal characters in the case of FIG. 2A and bold characters in the case of FIG. 2B. it can. As described above, when changing the position of the ink meniscus, the same amount of input energy can be input in both cases (a) and (b) to change the ink ejection amount. Further, by making the energy in the case of (b) larger than the energy in the case of (a), the ink ejection amount can be further increased.

Next, a concrete experimental example will be described. Experimental Example 1 Heating element size 28 μm × 140 μm Heating element resistance value 128Ω Orifice size 28 μm × 29 μm Distance from orifice to tip of heating element 180 μm Ink used DeskJ manufactured by Hewlett Packard
Ink of et Paper used for printing Matte coated paper made by Mitsubishi Paper Mills NM Pixel size measurement sample number n = 10 Continuous drive frequency 4.6 kHz Printing is performed by changing the ink meniscus position using the above conditions and the recording head. The results are shown in Table 1.

[Table 1]

In this experiment, the measurement of the position of the ink meniscus is not visible when using ink, so
Using a vehicle in advance (a transparent solution from which the dye component has been removed from the ink, the physical properties are almost the same as the ink), the position of the ink meniscus is varied and measured, and the relative position between the ink supply means and the recording head at that time. The height relationship was investigated, and then the vehicle of the recording head was changed to ink, and the ink meniscus was set according to the conditions to carry out actual testing. When measuring the position of the meniscus, use the orifice surface as a reference, and add a plus sign if the meniscus is outside the orifice surface and a minus sign if the meniscus is retracting inward from the orifice surface. There is.

As is clear from Table 1, it can be understood that the pixel diameter changes depending on the position of the meniscus.
Further, it can be seen that even at the same meniscus position, the pixel diameter changes due to the difference in drive voltage.

Next, another example to which the present invention is applied will be described with reference to FIG. In the drawing, 12 is a flying ink drop,
Reference numeral 13 indicates the shape of the pixel on the paper, and 14 indicates the drive pulse. FIG. 3A shows a uniform flying ink amount that operates in the same manner as described with reference to FIG. 1, and as a result, the pixel diameter recorded on the recording paper is almost constant, that is, binary recording. It becomes an image.

On the other hand, in FIG. 3B, one or more pulse energies are applied at fine intervals, and one or more minute ink droplets 12 ₁ to ₁ 1 are added according to the energy.
2 ₄ is formed. Further, depending on different conditions, these minute ink droplets may not be independent, but may fly as one continuous ink droplet having a bump-shaped bulge according to the input pulse energy number.

The pulse energy input in the case of FIG. 3 (b) is smaller than the pulse energy of FIG. 3 (a), so that the ink droplets formed are also small. In addition, this small pulse energy has a high frequency (several to several tens of kHz) and one to several pulses are applied, so that as shown in FIG. By ejecting and ejecting them as one connected ink column, they adhere to the paper surface to form pixels. Since these minute ink droplets adhere to the paper surface in a short time, a plurality of ink droplets form one pixel. In other words, gradation recording is performed in which the pixel size is changed according to the number of ink drops.

In short, one recording head is used, the operation shown in FIG. 3A is performed for the character information (binary recording information), and the image information (multi-value recording information) is used. , And can be used for performing the operation shown in FIG. 3B, and can handle all kinds of image information.
In the case of this embodiment, the size of one ink drop is different between the case shown in FIG. 3A and the case shown in FIG. 3B, and in order to form the different ink drops. It is necessary to appropriately change the position of the ink meniscus. That is, in the case of FIG. 3A, the position of the ink meniscus is not pulled in that much as shown in FIG. 2B, and in the case of FIG. 3B, the position of FIG. )
As shown in, each is set in a state in which it is pulled in relatively deep.

Next, another concrete example will be described. Actual Example 2 Using the same recording head as in Actual Example 1, printing was performed by changing the ink meniscus position, the number of pulses, etc., and the evaluation results are shown in Table 2.

[Table 2]

The method of measuring and setting the position of the meniscus is the same as that in the practical example 1, and
Observation was carried out by means of e and then printing was carried out by substituting with ink. The continuous drive frequency is No. If 1, 4.6
kHz, and No. 2 to No. In the case of 9, the driving frequency of the plurality of pulse groups was 4.6 kHz, and the generation frequency of the plurality of pulses in the pulse group was 30 kHz. As is apparent from Table 2, it is understood that the pixel diameter can be changed by changing the meniscus position and the input energy, and any image output can be dealt with.

Next, another example of changing the ink meniscus position will be described. The ink supply means shown in FIG.
When performing a printing operation that consumes a large amount of ink, the ink level of the ink supply unit becomes low due to the large consumption, so the height h in the figure changes. In order to eliminate this displacement of the height h, in FIG. 4, the ink container 33A of the ink supply means overflows the ink and always keeps the height h constant, thereby maintaining the ink meniscus at a constant position. There is. As means for overflowing, the ink is supplied to the outside of the ink container 33A of the ink supplying means.
Container 36 for receiving overflow ink and container 36
A pipe 37 for circulating the ink to the ink container 33A and a pump 38 are provided in the pipe 37. In the embodiment of FIG. 4, the position of the ink meniscus is changed by moving the ink supply means K with the recirculation device up and down in the area surrounded by the alternate long and short dash line.

FIG. 5 shows another modification for changing the position of the ink meniscus of the present invention. In this embodiment, a recording head H including a lid substrate 21, a heating element substrate 22, an orifice 24, a flow path 25, a region 26 for forming a liquid chamber, a heating element (heater) 29, and the like on a substrate 40, An ink cartridge 39 is arranged via a solenoid 41, and the ink cartridge 39 and the liquid chamber 2 of the recording head H are arranged.
A pipe 34 having a flexible region 34a is connected to the pipe 6 and the pipe 6.

In such a configuration, the solenoid 41
The height h of the ink cartridge 39 can be changed by applying an ON / OFF signal to the ink cartridge 39. By switching the height h of the ink cartridge 39, the position of the meniscus at the orifice 24 of the recording head can be changed. The height h of the ink cartridge 33 can be switched without difficulty by the flexible region 34a provided in the pipe 34. The end 34b of the pipe 34 on the ink cartridge side is formed in a needle shape so that it can be inserted into the connection hole 39b of the ink cartridge 39, and the end 34b of the pipe 34 extends from the needle end 34b of the ink cartridge 39. Since it can be inserted and removed, the ink cartridge 39 can be easily replaced. Reference numeral 39a is an atmosphere communication hole formed in the ink cartridge 39.

FIG. 6 shows a modification of the ink cartridge shown in FIG. This ink cartridge 3
9A has a configuration in which a foam material 55 is arranged inside and ink is impregnated in the foam material 55. With such a configuration of the ink cartridge, it is possible to prevent the ink from jumping out from the atmosphere communication hole of the ink cartridge due to the vibration, and to prevent bubbles from being generated inside. Polyurethane foam is effective as the foam material.

[0059]

The structure of the present invention provides a means for changing the position of the ink meniscus, and the same orifice enables not only normal size printing but also thick and dark printing as appropriate. In addition, by changing the position of the ink meniscus and the input energy, a large change in the pixel diameter can be obtained, and binary recording and multilevel recording can be performed, which has the advantage of enabling any image output. Have.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the relationship between a recording head portion and an ink supply unit for explaining the configuration and function of the present invention.

2A and 2B are explanatory views illustrating a case where the positions of ink meniscuses at the orifices are different.

FIG. 3 is an explanatory diagram showing a relationship between a flying ink (a) having a constant pixel diameter, a plurality of flying ink droplets (b) having different pixel diameters, and a pulse in a recording unit using a thermal inkjet.

FIG. 4 is a schematic cross-sectional view of another embodiment of changing the position of the ink meniscus of the present invention.

FIG. 5 is a schematic cross-sectional view of another embodiment of changing the position of the ink meniscus of the present invention.

6 is a schematic cross-sectional view showing one embodiment of a modification of the ink cartridge shown in FIG.

FIG. 7 is a perspective view showing an example of a bubble jet head to which the present invention is applied.

8 is an exploded perspective view of a lid substrate (a) and a heating element substrate (b) that form the recording head shown in FIG.

9 is a perspective view of the lid substrate shown in FIG. 8A as viewed from the back side.

FIG. 10 shows a sectional view (a) from the front for explaining the configuration of a main part of the liquid jet recording head, and a sectional view (b) taken along the line xx of FIG.

FIG. 11 is a detailed cross-sectional view for explaining the structure of a bubble generating portion using a thermal resistor.

12A to 12G are drawings for explaining the principle of ink ejection by a bubble jet.

FIG. 13 is a cross-sectional view of essential parts of the bubble jet type inkjet recording head (EDGE SHOOTER) described in FIG.

FIG. 14 is a cross-sectional view of a main part of a bubble jet type ink jet recording head (SIDE SHOOTER).

15A to 15E are operation explanatory views of the inkjet recording head shown in FIG.

FIG. 16 is an explanatory diagram illustrating the relationship between the pulse width and the appearance of bubbles.

[Explanation of symbols]

 1, 21 Lid substrate 2, 22 Heating element substrate 4, 24 Orifice 5, 25 Flow path 9, 29 Heating element (heater) 11, 31 Bubble 12, 32 Flying ink droplet 23 Recording liquid inlet 26 To form a liquid chamber Area 33 Ink container 34, 37 Pipe 35 Ink 36 Container for receiving overflow ink 38 Pump 39 Ink cartridge 40 Substrate 41 Solenoid 55 Foam material H Recording head

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 9012-2C B41J 3/04 103 X

Claims (4)

[Claims] 1. An orifice for ejecting ink, a thermal energy acting portion provided in a flow path leading to the orifice, a liquid chamber containing the orifice and the flow path for holding ink, and ink is supplied to the liquid chamber. In the liquid jet recording apparatus for recording by ejecting ink as droplets onto a recording medium, the orifice side and the means for supplying ink to the liquid chamber are relatively positioned in the height direction. A liquid jet recording apparatus characterized by being variable. 2. An orifice for ejecting ink, a thermal energy acting portion provided in a flow path leading to the orifice, a liquid chamber containing the orifice and the flow path for holding ink, and ink is supplied to the liquid chamber. A liquid jet recording apparatus for recording by ejecting ink as droplets onto a recording medium, and recording by changing the position of the ink meniscus at the orifice. 3. An orifice for ejecting ink, a thermal energy acting portion provided in a flow path leading to the orifice, a liquid chamber containing the orifice and the flow path for holding ink, and ink is supplied to the liquid chamber. A liquid jet recording apparatus for recording by ejecting ink as droplets onto a recording medium by changing the position of the ink meniscus at the orifice and changing the input energy to the thermal energy acting portion. A liquid jet recording method characterized by recording. 4. An orifice for ejecting ink, a thermal energy acting portion provided in a flow path leading to the orifice, a liquid chamber containing the orifice and the flow path for holding ink, and supplying the ink to the liquid chamber. A liquid jet recording apparatus for recording by ejecting ink as droplets onto a recording medium, when the image information is binary information, a substantially constant energy is input to the thermal energy acting unit, When the ink having a substantially constant mass is ejected from the orifice, and the image information is multi-valued information, the ink meniscus of the orifice is retracted more than in the case of binary information, and the energy smaller than the substantially constant energy is 1 to plural. A liquid jet recording method characterized in that the ink is ejected once and the ink ejection amount is changed according to the number of inputs.