JPH02153746A - Liquid-jet recording apparatus - Google Patents

Abstract

PURPOSE:To easily prevent cloggings of a nozzle at a low cost by terminating a wall defining a flow passage before an end face of a nozzle substrate and forming a top plate and said nozzle substrate in the shape of slits at a front end of an orifice. CONSTITUTION:A heater 64, an electrode 63 and a protecting layer 65 are laminated on a nozzle substrate, whereby a heater board is formed. A photosensitive dry film 75 is laminated on this board. A mask 76 patterned so that a desired flow passage and an ink liquid chamber are formed is overlapped with the heater board laminated with the dry film 75. Thereafter, the heater board is exposed. The exposed part of the film 75 is hardened through photopolymerization. The part not exposed is dissolved and removed when the film 75 is developed after exposure, whereby the wall of the flow passage is formed. However, an end face 71 of the wall of the flow passage forming the end of a discharging section of ink drops terminates at a point several mum-several hundred mum to this side of the end face of the nozzle substrate. Then, the heater board is joined via a glass top plate 70 and an adhesive layer 62. As a result, a nozzle section can be prevented from being clogged without affecting stability of discharged ink drops at a low cost with a small number of processes.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid jet recording apparatus, and more particularly to a device for preventing clogging of nozzles in a recording head of a bubble diene 1 to a printer.

The non-impact recording method has recently attracted attention because the noise generated during recording is so small that it can be ignored. Among them, high-speed recording is possible,
In addition, the so-called inkjet recording method, which allows recording on TT paper without the need for special fixing processing, is an extremely powerful recording method, and various methods have been proposed and improvements have been made to improve the quality of products. Some have been developed, and efforts are still being made to put them into practical use.

In this type of inkjet recording method, recording is performed by causing droplets of a recording liquid called ink to fly and adhere to a recording member. There are several types of methods depending on the control method used to control the flight direction of the generated recording liquid droplets.

First, the first method is the one (Tale type method) disclosed in, for example, US Pat. Recording is performed by controlling the droplets with an electric field in accordance with a recording signal to selectively attach recording liquid droplets onto a recording member.

To explain this in more detail, an electric field is applied between the nozzle and the accelerating electrode to eject a negatively charged recording liquid droplet from the nozzle, and the ejected recording liquid droplet is converted into a recording signal. Accordingly, recording is carried out by causing a beam to fly between the x and y deflection electrodes, which are configured to be electrically controllable, and by selectively adhering small particles onto the recording member by changing the intensity of the electric field.

The second method is a method (Sweet method) disclosed in, for example, U.S. Pat. No. 3,596,275, U.S. Pat. Recording is performed on a recording member by generating droplets with a controlled amount of charge and flying the generated droplets between deflection electrodes to which a negative electric field is applied.

Specifically, the orifice (discharge [1
) is configured so that the recording signal is applied before the 411
: A set of electrodes is placed a predetermined distance apart, and an electric signal of a constant frequency is applied to the piezoelectric vibrating element to mechanically vibrate the piezoelectric vibrating element, thereby ejecting small droplets of recording liquid from the ejection opening. At this time, a charge is electrostatically induced in the recording liquid droplet discharged by the charging electrode, and the droplet is charged with an electric charge corresponding to the recording signal. When a droplet of recording liquid with a controlled amount of charge flies between deflection electrodes to which a constant electric field is uniformly applied, it is deflected according to the amount of charge added, and the droplet carries the recording signal. only can be deposited on the recording member.

The third method is, for example, the method disclosed in U.S. Pat. This method records by generating and atomizing small droplets. That is, in this method, the atomization state of droplets is controlled by modulating the electric field intensity applied between the nozzle and the charging electrode in accordance with the recording signal, and the gradation of the recorded image is produced.

The fourth method is 1, for example, the method disclosed in U.S. Pat. No. 3,747,120 (StCIIIIIIe method).
This method is fundamentally different in principle from the above three methods.

That is, in all three methods, the droplets of recording liquid ejected from the nozzle are electrically controlled while they are in flight, and the droplets carrying the recording signal are selectively attached to the recording member. In contrast, recording is performed by

This Stem+se method performs recording by ejecting small droplets of recording liquid from an ejection port in response to a recording signal.

In other words, the Stemme method applies an electrical recording signal to a piezo vibrating element attached to a recording head that has an ejection port for discharging recording liquid, and converts this electrical recording signal into mechanical vibration of the piezo vibrating element. In this method, recording is performed by ejecting small droplets of recording liquid from the ejection opening according to the mechanical vibrations and adhering them to the recording member.

Each of these four conventional methods has its own advantages, but there are also drawbacks that can be solved in the other method.

That is, in the first to third methods, the direct energy of one generation of a recording liquid droplet is electrical energy, and
Deflection control of droplets is also electric field control.

Therefore, although the first method is simple in structure, it requires a high voltage to generate droplets, and it is difficult to use a multi-nozzle recording head, making it unsuitable for high-speed recording.

The second method allows the recording head to have multiple nozzles and is suitable for high-speed recording, but it has a complicated structure, and the electrical control of recording liquid droplets is sophisticated and difficult, and satellite dots are placed on the recording member. There are problems such as easy occurrence of.

The third method has the advantage of being able to record images with excellent gradation by atomizing recording liquid droplets, but on the other hand, it is difficult to control the atomization state and fog occurs in the recorded image. In addition, it is difficult to create a multi-nozzle recording head.
There are various problems such as being unsuitable for high-speed recording.

The fourth method has relatively many advantages compared to the first to third methods. That is, the configuration is simple, and in order to perform recording by ejecting the recording liquid from the ejection opening of the nozzle on-demand, a small ejecting liquid is used as in the first to third methods. It is unnecessary to collect droplets that are not needed for recording an image among the droplets, and the 17th
! Unlike the second method, this method has great advantages in that there is no need to use a conductive recording liquid and there is a large degree of freedom regarding the material of the recording liquid. On the other hand, it is difficult to make the recording head multi-nozzle because there are problems in processing the recording head, and it is extremely difficult to miniaturize the piezoelectric vibrating element having the desired resonance number. This method has drawbacks such as that it is not suitable for high-speed recording because the recording liquid droplets are ejected and ejected in flight using the mechanical energy of the mechanical vibration of the piezoelectric vibrating element.

Furthermore, Japanese Patent Application Laid-Open No. 48-9622 (corresponding to the above-mentioned US Pat. No. 3,747,120) discloses, as a modification,
It is described that thermal energy is used instead of using mechanical vibration energy by means such as the piezo vibration element described above.

That is, the above-mentioned publication describes a so-called bubble jet liquid jet recording device that uses a heating coil that directly heats liquid as a pressure increasing means instead of a piezo vibrating element to generate steam that causes a pressure increase. There is.

However, in the above publication, the liquid ink in the bag-shaped ink chamber (liquid chamber), which has only one opening through which liquid ink can go in and out, is directly heated and vaporized by energizing the heating coil as a pressure increasing means. However, when discharging liquid continuously and repeatedly, how to heat it is described in 5.
There is nothing to suggest. In addition, the heating coil is located at the deepest part of the bag-shaped liquid chamber far from the liquid ink supply path, which makes the head structure complicated and requires continuous high-speed printing. For repeated use,
It is not suitable.

Moreover, based on the technical content described in the above publication.

After discharging a liquid using the generated heat, which is of practical importance, it is impossible to quickly prepare for the next liquid discharge.

As described above, conventional methods have advantages and disadvantages in terms of structure, high-speed recording, multi-nozzle recording heads, generation of satellite dots, and fogging of recorded images. There was a restriction that it could only be applied.

Furthermore, in JP-A-52-21833, a nozzle gun is covered with a nozzle cover, and the nozzle cover is provided with a solvent supply port and a solvent discharge port to allow the solvent to flow, and this flow covers the nozzle tip. , 41i construction is complicated and costs increase. Also, since it uses a solvent, it lacks safety.

JP-A-59-12367023670 An energy generating body for forming droplets is located in the groove, and this forms the ejection port, but the pressure wave caused by the energy generating body
It is not efficiently transmitted to the 7j15 outlet.

Energy loss is large and dispensing is very difficult.

Purpose The present invention was made in order to solve the above-mentioned drawbacks, and an object of the present invention is to provide a liquid jet recording device that can easily and inexpensively prevent clogging of nozzles in an inkjet printer head. This was done as a.

Also 1-Issei.

In order to achieve the above object, the present invention provides a thermal energy application unit that accommodates the recording liquid introduced, generates bubbles in the recording liquid by heat, and generates an acting force as the body M of the bubbles increases. an orifice connected to the flow path for ejecting the recording liquid as a droplet by the acting force, and an orifice connected to the flow path for introducing the recording liquid into the flow path. In a liquid jet recording device comprising a liquid chamber and an introduction means for introducing recording liquid into the liquid chamber, the wall forming the flow path ends before the end surface of the nozzle substrate, and the top plate and the nozzle are connected at the tip of the orifice. It is characterized in that the substrate is formed into a slit shape.

First, referring to FIG. 7, the principle of ink ejection using a bubble jet will be explained.

In the figure, 21 is a lid substrate, 22 is a heating element plate, 27 is a selection (independent) electrode, 28 is a common electrode, 29 is a heating element (heater), 30 is ink, 31 is a bubble, and 32 is a flying ink droplet. be.

(a) is a steady state, in which the surface tension of the ink 30 and the external pressure are in equilibrium on the orifice surface.

In (b), the heater 29 is heated, and the surface temperature of the heater 29 rises rapidly until boiling PA development occurs in the adjacent ink layer, and microbubbles 31 are scattered.

(c) shows a state in which the adjacent ink layer that 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 inside the nozzle rises by the amount of bubble growth, and the balance with the external pressure on the orifice surface is lost, and an ink column begins to grow from the orifice.

(d) shows a state in which the bubble has grown to its maximum, and 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 111 gas pulse.

(e) shows a state in which the bubbles 31 are cooled by ink or the like and begin to contract. At the tip of the ink column, it moves forward while maintaining the extruded speed, and at the rear end, the ink flows backward from the orifice surface into the nozzle due to the decrease in nozzle internal pressure as the bubbles contract, creating a constriction in the ink column. .

In (f), the air bubbles 31 are further contracted, the ink comes into contact with the heater surface, and the heater surface is cooled even more rapidly. At the orifice surface, the external pressure is higher than the nozzle internal pressure, so the meniscus is largely moving into the nozzle. The tip of the ink column becomes a droplet and drops 5 to 1 droplets toward the recording paper.
It is flying at a speed of o■+/sec.

In (g), the air bubbles have completely disappeared in the process of refilling the orifice with ink by capillary action and returning to the state of (a).

Figure 8 is a perspective view of the bubble jet recording head, Figure 9 is an exploded configuration diagram of the recording head, (,) is the lid substrate, (b)
10 is a diagram showing a heating element substrate, and FIG. 10 is a back view of the lid substrate shown in FIG. 9(a). In the figure, 23 is a recording liquid inlet, 24 is an orifice, 25 is a flow path, and 26 is a region for forming a liquid chamber.

FIG. 11 is a partial view of the bubble jet liquid jet recording head, in which (a) is a front partial view seen from the orifice side;
b) is a partial view cut along the dashed-dotted line XX in (a).

The recording head 41 shown in FIG. 11 has a predetermined number of grooves having a predetermined opening and depth at a predetermined linear density on a substrate 43 on which an electrothermal transducer 42 is provided on the back surface. By bonding a grooved plate 44 that covers the substrate 43, a liquid discharge portion 46 including an orifice 45 for ejecting liquid is formed.

The liquid discharge part 46 has a heat acting part 47 where the thermal energy generated by the orifice 45 and the electrothermal converter 42 acts on the liquid to generate bubbles and cause a sudden change in state due to expansion and contraction of the volume. and has.

The heat acting part 47 is connected to the L of the heat generating part 48 of the electrothermal converter 42.
The heat acting surface 49, which is the surface of the heat generating section 48 that comes into contact with the liquid, is the lower surface of the heat generating section 48. The heat generating section 48 is
It is composed of a lower layer 50 provided on the base 43, a heating resistor 51 provided on the lower layer 50, and an upper layer 52 provided on the heating resistor Jr 451.

The heating resistor JeJ51 includes a core layer 5 to generate heat.
Electrodes 53 and 54 for supplying electricity to the electrode 1 are provided on its surface, and a heat generating portion 48 is formed by a heat generating resistive layer between these electrodes.

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

The layer 52 isolates the heating resistor jn 51 from the liquid in the liquid discharge part 46 in order to chemically and physically protect the heating resistor layer 51 from the liquid used, and also prevents a short circuit between the electrodes 53 and 54 through the liquid. It has the protective function of the heat generating resistor layer 51 to prevent this from occurring.

The upper WJ 52 has the above-mentioned functions, but if the heating resistance layer 51 is liquid resistant and there is no need for electrical short-circuiting between the electrodes 53 and 54 through liquid, It is not necessary to provide such an electrothermal transducer, and the electrothermal transducer may be designed to have a structure in which the liquid comes into immediate contact with the surface of the heat generating resistance layer 51.

The lower layer 50 has a heat flow control function, that is, when ejecting droplets, the heat generated in the heat generating resistor layer 51 is transferred to the substrate 43.
The proportion of conduction toward the heat-effecting portion 47 side is increased as much as possible than the conduction toward the side, and after the droplet is ejected, that is, after the electricity to the heat-generating resistor layer 51 is turned off, the heat-effecting portion 4
7 and the heat generating part 48 is quickly released to the substrate 43 side, and the liquid in the heat acting part 47 and the generated bubbles are rapidly cooled.

In general, one of the causes of clogging is that if the ink is left unprinted for a long period of time, the ink in the orifice that is in contact with the atmosphere dries and the viscosity increases.

The present invention is characterized in that the tip of the nozzle is formed into a slit shape in order to prevent the ink viscosity near the orifice from increasing when printing is not being performed. With this slit, the tip of the nozzle is always covered with a thin film of ink, which prevents the viscosity of the ink from increasing due to drying. below.

An explanation will be given based on an example of the present invention.

FIG. 1 is a perspective view of an ink droplet ejection section, for explaining an example of a liquid jet recording apparatus according to the present invention. In the figure, 61 is the nozzle, 62 is the adhesive part, 63 is the main electrode,
64 is a heater, 65 is a protective layer, 66 is 5iO-Jt'
J, 67 is a Si substrate, 68 is an ink chamber, 69 is an ink supply port, 70 is a glass top plate, 71 is an end face of a channel wall, 72
is the end face of the nozzle substrate.

FIG. 2 is a diagram showing the manufacturing process of the recording head.
5 is a photosensitive dry film, and 76 is a mask.

(a) Heater 64. The electrode 63 and the protective layer 65 are deposited using photolithography, etching, and sputtering techniques. IL forms the heater board.

(b) A photosensitive dry film 75 is laminated on the heater board, a mask 7G patterned so as to obtain the desired flow path and ink chamber is placed on top of the mask 7G, and exposure is performed from above.

(c) The exposed portion of the photosensitive dry film 75 undergoes a photopolymerization reaction and is cured. Therefore, when development is performed after exposure, the unexposed portions are dissolved and removed to form the walls of the channel. At this time, as shown in the shaded area of FIG.
It ends a few hundred micrometers short. At this time, the photosensitive dry film 7 that forms the side surface of the ink droplet ejection surface
5, the end face 71 of the wall forming the flow path as shown in the shaded area is
It does not necessarily have to reach the nozzle board end face 72;
Like the photosensitive dry film that creates other flow paths, it may end before the nozzle substrate end face 72.

(d) Next, it is joined to the glass top plate 70 via adhesive J (glue 62). This glass top plate 70 is drilled in a portion corresponding to the ink chamber to supply ink to the ink chamber 68. The supply port 69 has been processed.

FIG. 4 is a cross-sectional view taken along line A-A in FIG. 3, where 73 is a meniscus portion and 74 is ink. The meniscus portion 73 is in an equilibrium state between the surface tension of the ink 74 and external pressure, and when thermal energy is generated in the heater 64, ink droplets can be ejected using the same principle as shown in FIG.

Furthermore, as shown in FIG. 5, when forming the ink chamber 68 and the flow channel wall 71, instead of laminating the photosensitive dry film 75 on the nozzle substrate side as described above, the photosensitive dry film 75 is laminated on the glass top plate 70 side. It can also be produced by laminating it through a process similar to that shown in FIG.

Alternatively, as shown in FIG. 6, the desired ink chamber 68 and flow path can be formed by directly etching the glass top plate 70.

When photosensitive glass is used for the glass top plate 70, when the photosensitive glass is exposed to light in a desired flow path pattern of the ink chamber 68, only the exposed portions are opalescent.

This opalescent glass portion can be etched with dilute hydrofluoric acid.

Note that the top plate 70 is not limited to the above-mentioned glass, but may also be made of ceramic, resin, or metal, but in order to connect it to the heater board, an adhesive material is laminated on the top plate, or it is glued to the top plate itself. Preferably something with gender.

As is clear from the above explanation, according to the present invention, the structure is very simple, the number of steps is small, the cost is low, and the stability of the ejected ink droplets is not compromised.

It is possible to prevent clogging of the nozzle part.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an ink droplet ejecting section, and FIGS. 2(a) to 2(d) are for explaining an embodiment of a liquid jet recording apparatus according to the present invention. FIG. 3 is a diagram for explaining the wall of the channel, and FIG. 4 is a diagram showing the walls of the channel.
FIG. 3 is a sectional view taken along line A-A in FIG. 3, FIG. Figure 7 is a principle diagram of bubble jet ink discharge and bubble generation/disappearance in the recording head, Figure 8 is a perspective view of the recording head, Figure 9 is an exploded configuration diagram of the recording head, and (a) shows the lid substrate. , (b) is a diagram showing the heating element substrate, FIG. 10 is a back view of the cover substrate of the recording head, FIG. 11 is a partial view of the recording head, and (a) is a partial front view of the head as seen from the orifice side. , (b) is a partial view taken along line XX of (a). 61... Nozzle, 62... Adhesive layer, 63... Electrode, 64... Heater, 65... Protective layer, 66... S
i○2/l'l, 67...Si substrate, 68 ink chamber,
69... Ink supply port, 70... Glass top plate, 71
...The end face of the channel wall. 72... Nozzle substrate end surface, 73... Meniscus portion, 74... Ink, 75... Dry film, 76
···mask. Figure 1 Figure 3 Figure 4 Figure 2 (C) (d) (d Figure ○#=: Figure IQ) Figure (b) Section

Claims (1)

[Claims] 1. A flow path that accommodates the recording liquid to be introduced and is provided with a thermal energy acting section that generates bubbles in the recording liquid using heat and generates an acting force as the volume of the bubbles increases; an orifice in communication with which the recording liquid is ejected as a droplet by the acting force, a liquid chamber in communication with the flow path and with which the recording liquid is introduced into the flow path, and a recording liquid in the liquid chamber. In a liquid jet recording device comprising an introduction means for introducing a liquid, the wall forming the flow path ends before the end face of the nozzle substrate, and the top plate and the nozzle substrate are formed in a slit shape at the tip of the orifice. Characteristic liquid jet recording device.