JP2738697B2 - Liquid jet recording head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid jet recording head, and more particularly, to a cooling means for a bubble jet type ink jet recording head.

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

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

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

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

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

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

The fourth method is, for example, a method (Stemme method) disclosed in US Pat. No. 3,747,120. This method is fundamentally different from the above three methods in principle.

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

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

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

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

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

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

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

Furthermore, Japanese Patent Application Laid-Open No. 48-9622 (corresponding to the above-mentioned US Pat. No. 3,747,120) describes, as a modification, the use of thermal energy instead of the mechanical vibration energy by means such as the piezo-vibration element. Have been.

That is, the above-mentioned publication describes that a heating coil that directly heats a liquid in order to generate a vapor that causes a pressure increase is used as a pressure increasing means instead of the piezoelectric vibrating element.

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

In addition, according to the technical contents described in the above-mentioned publication, it is impossible to quickly form a preparation state for the next liquid discharge after the generated heat, which is practically important, performs the liquid discharge.

As described above, the conventional method has advantages and disadvantages in terms of configuration, high-speed recording, multi-nozzle recording head, generation of satellite dots and occurrence of fogging of a recorded image, etc. There was a restriction that only the application was possible.

Japanese Patent Application Laid-Open No. Sho 60-143970 discloses a liquid comprising an orifice, an energy generator, a liquid flow path, one or more series of ejection droplet forming means formed from a liquid reservoir, a heater and a temperature sensor. In the ejection recording head,
The recording head is surrounded by heat insulating means, so that the temperature rises quickly to the set temperature, the temperature distribution can be controlled uniformly, and stable ejection is achieved by keeping the head temperature constant irrespective of changes in the environmental temperature. There is described an ink jet recording apparatus capable of giving high print quality.

However, in order to obtain a high response frequency in the bubble jet type ink jet recording head, it is desired that the ink temperature is low and the generated bubbles are instantaneously cooled and disappear. Therefore, when the head is surrounded by the heat insulating means, the head temperature becomes high, and it becomes impossible to drive at a high response frequency. Further, in a multi-array in which the number of orifices is large, the amount of generated heat is very large, and unless some cooling means (radiation means) is provided, the entire apparatus has too much heat and substantially hinders operation. There is a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in particular, in a valve jet type liquid jet recording head, a cooling means is provided in a thermal energy action section to stabilize droplet ejection performance. It is done for the purpose of.

Configuration In order to achieve the above object, the present invention provides a thermal energy operating section that accommodates a recording liquid to be introduced, generates bubbles in the recording liquid by heat, and generates an action force accompanying an increase in the volume of the bubbles. And an orifice communicating with the flow path to discharge the recording liquid as droplets by the action force, and an orifice communicating with the flow path to introduce the recording liquid into the flow path. A liquid chamber, and a liquid jet recording head comprising means for introducing the recording liquid into the liquid chamber, the liquid jet recording head having forced cooling means for cooling the liquid jet recording head, wherein the forced cooling means A tube is wound around the tube, and a cooling liquid is caused to flow into the tube. Alternatively, the substrate on which the thermal energy action section is formed has a passage for passing the liquid, and the liquid By flowing, the thermal energy acting portion is cooled, or the thermal energy acting portion is formed on a substrate made of a porous member having a heat storage layer on an upper portion, and the porous member has It is characterized in that a cooling liquid is infiltrated. Hereinafter, a description will be given based on examples of the present invention.

FIG. 4 is a view for explaining the operation of a bubble jet head as an example of an ink jet head to which the present invention is applied, FIG. 5 is a perspective view showing an example of a bubble jet head, and FIG. A lid substrate (FIG. 6 (a)) and a heating element substrate (FIG. 6 (b)) which constitute the head shown in FIG.
FIG. 7 is a perspective view of the lid substrate shown in FIG. 6 (a) viewed from the back side, in which 11 is a lid substrate,
12 is a heating element substrate, 13 is a recording liquid inlet, 14 is an orifice, 15 is a flow path, 16 is a region for forming a liquid chamber, 17 is an individual (independent) electrode, 18 is a common electrode, and 19 is a heating element (Heater), 20 is a recording liquid (ink), 21 is a bubble, and 22 is a flying ink droplet. 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. 4. (a) is a steady state, in which the surface tension of the ink 30 and the external pressure are in an equilibrium state at the orifice surface.

6B, the heater 19 is heated, the surface temperature of the heater 19 rises rapidly, and boiling development occurs in the adjacent ink layer, so that the heater 19 is heated and the microbubbles 21 are scattered.

(C) is a state in which the adjacent ink layer heated rapidly on the entire surface of the heater 19 is instantaneously vaporized to form a boiling film, and the bubbles 21 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 20 corresponding to the volume of the bubble is pushed out from the orifice surface. At this time, no current is flowing through the heater 19, and the surface temperature of the heater 19 is decreasing. The maximum value of the volume of the bubble 21 is slightly delayed from the timing of applying the electric pulse.

(E) shows a state where the bubble 21 is cooled by ink or the like and starts to contract. At the front end of the ink column, the ink moves forward while maintaining the pushed speed, and at the rear end, the ink flows backward from the orifice surface into the nozzle due to a decrease in the nozzle internal pressure due to the contraction of the bubble, and the ink column is constricted. .

4F, the bubble 21 is further contracted, the ink comes into contact with the heater surface, and the heater surface is cooled more rapidly. At the orifice surface, the external pressure is higher than the internal pressure of the nozzle, so that the meniscus largely enters the nozzle. The tip of the ink column 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.

The present invention relates to a head cooling means in a valve jet type liquid jet recording head as described above, and stabilizes droplet discharge performance by cooling the head. In addition, the operation of the entire apparatus can be stabilized by releasing a huge amount of heat generated from the head. Further, the present invention is particularly effective for a bubble jet type head having a multi-array configuration.

FIGS. 1 to 3 are perspective views for explaining an embodiment of the present invention. In the drawings, the same portions as those of the head shown in FIGS. Parts having the same functions as those of the heads shown in FIGS. 7 to 9 are denoted by the same reference numerals as those in FIGS. Thus,
In the embodiment shown in FIG. 1, a tubular liquid supply pipe 1 is provided around the head, and the entire head is cooled by flowing a liquid (for example, water).

The embodiment shown in FIG. 2 is a heating element substrate of a head.
At the bottom of 12, for example, a hole 2 for flowing a liquid is provided,
By flowing a liquid there, the heating element is intended to be cooled more effectively.

FIG. 3 is a view for explaining another embodiment of the present invention. The heating element substrate 12 is made of a porous member (for example, sintering ceramic) 3 and is supplied by a liquid supply means (not shown). Is infiltrated. When the head starts to generate heat, the liquid (for example, water) evaporates, and the head is cooled by the heat of vaporization released at that time. In addition,
In order to release the heat of vaporization more effectively, air may be blown by a fan or the like to the heat generating substrate of the porous member into which the liquid has penetrated, to promote the vaporization and the release of the heat of vaporization. Note that a heat storage layer 4 made of, for example, SiO ₂ is provided on the porous member (opposite to the surface from which the heat of vaporization is released). The heat storage layer 4 includes a recording liquid (ink) and ( Prevents contact with liquid (for cooling).

Although all of the above description has been made with reference to an example of a bubble jet recording head using a heating element as a bubble generating unit, the present invention uses a pulse laser or a discharge energy as a bubble generating unit. The present invention can also be applied to a bubble jet recording head that performs the operation.

FIG. 8 is a view for explaining another means for generating bubbles in the recording liquid. In the figure, 31 is a laser oscillator, 32 is a light modulation drive circuit, 33 is a light modulator, 34 is a scanner, 35 Is a condenser lens, and the laser light generated by the laser oscillator 31 is pulse-modulated in the optical modulator 33 in accordance with an image information signal which is input to the optical modulator driving circuit 32, is electrically processed, and is output. . The pulse-modulated laser light passes through a scanner 34 and is condensed by a condenser lens 35 so as to be focused on the outer wall of the thermal energy action section. To generate air bubbles. Alternatively, the wall 36 of the thermal energy action section is made of a material that is permeable to laser light,
Bubbles may be generated by focusing the light so as to focus on 37 and directly heating the recording liquid.

FIG. 9 is a view for explaining an example of a printer using a laser beam as described above. The nozzle section 41 has a high density (for example, 8 nozzles / mm) and a paper width (for example, A
4 width) shows an example in which the components are integrated so as to cover the entirety.

The laser light emitted from the laser oscillator 31 is applied to an optical modulator.
Guided to 33 entrance openings. In the optical modulator 33, the laser light is subjected to strong and weak modulation according to an image information input signal to the optical modulator 33. The optical path of the modulated laser light is bent by the reflector 38 in the direction of the beam expander 39, and enters the beam expander 39. The beam diameter is expanded by the beam expander 39 while keeping the parallel light.
Next, the laser beam having the expanded beam diameter is incident on a rotating polygon mirror 40 that rotates at a high speed and a constant speed. The laser light swept by the rotating polygon mirror 40 forms an image on the outer wall 36 of the thermal energy action section of the drop generator or on the recording liquid inside by the condenser lens 35. As a result, air bubbles are generated in each of the thermal energy action sections, and the recording liquid droplets are ejected to perform recording on the recording paper.

FIG. 10 is a view showing still another bubble generating means. In this example, a pair of discharge electrodes 50 arranged on the inner wall side of the thermal energy action section receives a high voltage pulse from a discharge device 51,
A discharge is generated in the recording liquid, and bubbles are instantaneously formed by heat generated by the discharge.

11 to 18 are diagrams showing specific examples of the discharge electrode shown in FIG. 10, respectively.The example shown in FIG. The discharge (with low energy) is caused to occur.

In the example shown in FIG. 12, two flat electrodes are used so that air bubbles are stably generated between the electrodes. The position of the generated bubble is more stable than the needle-shaped electrode.

In the example shown in FIG. 13, a substantially coaxial hole is formed in the electrode. Both holes of the two electrodes serve as guides, and the position of the generated bubbles is further stabilized.

The example shown in FIG. 14 is a ring-shaped electrode, and is basically the same as the example shown in FIG. 13, and is a modified embodiment thereof.

In the example shown in FIG. 15, one is a ring-shaped electrode and the other is a needle-shaped electrode. The ring-shaped electrode aims at stability of generated bubbles, and the needle-shaped electrode aims at efficiency by concentrating an electric field.

In the example shown in FIG. 16, one ring-shaped electrode is formed on the wall surface of the thermal energy action section. This aims at facilitating manufacture in which electrodes are formed two-dimensionally on the substrate, in addition to the effects of the example shown in FIG. A plurality of such planar electrodes having high density can be easily manufactured by vapor deposition (or sputtering) or photo-etching technology. Especially effective for multi-array.

In the example shown in FIG. 17, the ring-shaped electrode forming portion of the example shown in FIG. 16 is formed along the outer periphery of the electrode and is raised one step from the periphery. Again, the stability of the generated bubbles is aimed at, and it is more stable than that shown in FIG. 15 by adding a three-dimensional guide.

The example shown in FIG. 18 is different from the example shown in FIG. 17 in that the ring-shaped electrode forming portion has a structure in which it is dropped down from the surroundings. Is done.

Effects As is clear from the above description, according to the present invention, the head is effectively cooled and the ejection performance is stabilized.
Further, there is an advantage that the operation of the entire device can be stabilized when the entire device is enlarged due to a multi-array head or the like.

[Brief description of the drawings]

1 to 3 are configuration diagrams for explaining an embodiment of the present invention, and FIG. 4 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. 5 is a perspective view showing an example of a bubble jet head, FIG. 6 is an exploded perspective view, FIG.
FIG. 8 is a diagram illustrating the lid substrate viewed from the back side, FIG. 8 is a diagram illustrating an example of a bubble generating unit using laser light, FIG. 9 is a diagram illustrating an example of a printer, FIG. Figure 10
FIGS. 11 to 18 are diagrams for explaining an example of a bubble generating means using discharge, and FIGS. 11 to 18 are diagrams each showing a specific example of the discharge electrode shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Cooling water tube, 2 ... Cooling water supply hole, 3 ... Porous member, 4 ... Thermal storage layer, 11 ... Storage substrate, 12 ... Heating element substrate.

Claims (3)

(57) [Claims] 1. A storage device for accommodating a recording liquid to be introduced,
A flow path provided with a thermal energy action portion for generating bubbles in the recording liquid by heat and generating an action force in accordance with an increase in the volume of the bubbles; and connecting the recording liquid by the action force to communicate with the flow path. A liquid jet recording head comprising: an orifice for discharging droplets; a liquid chamber for communicating with the flow path to introduce the recording liquid into the flow path; and a means for introducing the recording liquid into the liquid chamber. And a forced cooling means for cooling the liquid jet recording head, wherein the forced cooling means winds a tube around the liquid jet recording head and causes a cooling liquid to flow through the tube. Liquid jet recording head. 2. A storage device for accommodating a recording liquid to be introduced,
A flow path provided with a thermal energy action portion for generating bubbles in the recording liquid by heat and generating an action force in accordance with an increase in the volume of the bubbles; and connecting the recording liquid by the action force to communicate with the flow path. A liquid jet recording head comprising: an orifice for discharging droplets; a liquid chamber for communicating with the flow path to introduce the recording liquid into the flow path; and a means for introducing the recording liquid into the liquid chamber. Wherein a liquid passage is provided for passing the liquid through the substrate on which the thermal energy acting portion is formed, and the thermal energy acting portion is cooled by flowing the liquid through the passage. Recording head. 3. A storage device for accommodating a recording liquid to be introduced.
A flow path provided with a thermal energy action portion for generating bubbles in the recording liquid by heat and generating an action force in accordance with an increase in the volume of the bubbles; and connecting the recording liquid by the action force to communicate with the flow path. A liquid jet recording head comprising: an orifice for discharging droplets; a liquid chamber for communicating with the flow path to introduce the recording liquid into the flow path; and a means for introducing the recording liquid into the liquid chamber. A liquid jet recording head, wherein the thermal energy action section is formed on a substrate made of a porous member having a heat storage layer on an upper portion thereof, and a cooling liquid is allowed to penetrate the porous member.