JP2815583B2 - Liquid jet recording method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid jet recording method, and more particularly, to a recording method using a bubble jet type liquid 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.

Moreover, according to the technical contents described in the above-mentioned publication, it is not possible to quickly form a preparation state for the next liquid discharge after performing the liquid discharge with the generated heat which is practically important.

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. 61-242850 has a head temperature detecting means in view of the fact that the ejection performance changes due to an increase in the temperature of the head, and detects the head temperature by the detecting means. Although the droplet discharge energy is supplied in accordance with the temperature, this method requires a temperature detecting means and its feedback control device, and thus has a disadvantage that the device becomes large and complicated.

The present invention has been made in view of the above-mentioned circumstances, and particularly, in a bubble jet type liquid jet recording method, even when recording is started immediately, or even after a certain period of time from the start of recording, uniform discharge droplets are obtained. The purpose of the present invention is to provide a liquid jet recording method capable of obtaining the following.

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. A orifice for communicating with the flow path to discharge the recording liquid as droplets by the action force, and introducing the recording liquid to the flow path by communicating with the flow path. In a liquid jet recording method in which recording is performed using a liquid jet recording head including a liquid chamber for introducing the recording liquid into the liquid chamber, the energy to be applied to the thermal energy action section is set at the start of recording and immediately thereafter. In this case, the recording is made larger, and after a certain time has elapsed, the recording is made smaller. Hereinafter, a description will be given based on an example of the present invention.

FIG. 1 is a main part configuration diagram for explaining one embodiment of a liquid jet recording method according to the present invention, and FIG. 2 is an operation explanation of a bubble jet head as an example of an ink jet head to which the present invention is applied. FIG. 3 is a perspective view showing an example of a bubble jet head, and FIG.
FIG. 4A is a perspective view of the head shown in FIG. 4 when disassembled into a lid substrate (FIG. 4A) and a heating element substrate (FIG. 4B). FIG. 11 is a perspective view of the lid substrate shown from the back, 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, and 16 is a liquid chamber. 17 is an individual (independent) electrode, 18 is a common electrode, 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. 2. (a) is a steady state, and the surface tension of the ink 20 and the external pressure are in an equilibrium state at the orifice surface.

3B shows a state in which the heater 19 is heated until the surface temperature of the heater 19 sharply rises and the adjacent ink layer is heated until boiling development occurs, and minute bubbles 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 stopper, the ink 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 reduction of the internal pressure of the nozzle due to the contraction of the bubble, and the ink stopper 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.

SUMMARY OF THE INVENTION The present invention provides a recording method in a bubble jet type liquid jet recording head as described above, in which the discharged droplets are always uniform, so that the image quality is stable and the apparatus is not large. Thus, there are two reasons why uniform ejection droplets cannot be obtained in the bubble jet type liquid jet recording. One of the reasons is that when recording is to be performed after stopping for a long time, FIG. As shown in a), the evaporation of the water from the orifice portion increases the viscosity of the recording liquid 20a near the orifice outlet, thereby increasing the fluid resistance at the time of ejection, and increasing the energy (eg, pulse) In the case of (voltage), power is insufficient, and a smaller amount is ejected than originally ejected. Another cause in this case is that the recording liquid 20b attached to the outside of the orifice becomes a resistance. Another reason why uniform ejection cannot be obtained is that the temperature of the recording liquid at the start of recording is different from the temperature of the recording liquid after a certain period of time, so that if the same energy is always applied, as shown in FIG. At a low temperature (immediately after the start of recording), since the bubbles 21 do not grow sufficiently large,
Also, at a high temperature (when a certain period of time has elapsed after the start of recording), as shown in FIG. 1 (c), the bubbles 21 grow large and the discharged droplets 22 become large.

Although the above two reasons are different physical phenomena, the same measures can be taken to eliminate the problem. In other words, one of the reasons is that it is difficult to discharge due to the fluid resistance caused by the high viscosity of the orifice recording liquid, and the other is that the recording liquid is at a low temperature and the thermal energy is insufficient and it is difficult to discharge. The problem can be solved by adding more energy at the start of injection.

The present invention focuses on the above points, and applies a slightly higher energy for a certain period of time from the start of recording,
After a certain period of time, the energy is reduced. Note that this energy level may be changed stepwise instead of a low high binary level. Further, the energy to be applied may be changed depending on time. However, since the patterns of the recorded images vary widely, the energy level may be changed by counting the number of ejected droplets. In addition, by providing a switching mode switch that allows a plurality of types to be set so that the predetermined time can be changed depending on the environmental temperature (or season), a constant high image quality can be always obtained.

Although an example in which a heating resistor is used as the bubble generating means has been described above, any well-known technique such as a pulse laser and a discharge energy may be used as the bubble generating means.

Effects As is clear from the above description, according to the present invention, since the discharged droplets are uniform at the start of recording and after a certain period of time, a high quality image can be obtained.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram for explaining an embodiment of the present invention, FIG. 2 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. 3 is a perspective view showing an example of a bubble jet head, FIG. 4 is an exploded perspective view, and FIG. 5 is a view of the lid substrate as viewed from the back. 11 ... lid substrate, 12 ... heating element substrate, 19 ... heating element, 20, 2
0a: Recording liquid, 20b: Adhered recording liquid, 21: Bubbles.

Claims (1)

(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 ejection recording head comprising: an orifice for discharging droplets; a liquid chamber communicating with the flow path and introducing the recording liquid into the flow path; and a means for introducing the recording liquid into the liquid chamber. In the liquid jet recording method for performing recording by using, the energy applied to the thermal energy acting portion is increased and recorded at the start of recording and immediately after the recording, and then reduced and recorded after a lapse of a certain period of time. Liquid recording method.