JPH05269986A - Method and apparatus for ink jet recording - Google Patents

Abstract

PURPOSE:To make constant ejection of ink possible. CONSTITUTION:Ink in an ink tank is sucked up into a passage, utilizing capillary action. Then, hydrogen bubbles 23 are produced in the ink by electrolysis and furthermore, plasma fluid 26 is produced by placing the hydrogen bubbles 23 in strong electric field. Isothermal expansion is applied to the hydrogen bubbles by applying thermal vibration to electrons in the plasma. At this time, the ink is ejected to the outside on thermodynamic work amount serving as motive force. The plasma fluid 26 is ejected at this time to the outside together with the ink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording system, and more particularly to an ink jet recording system for ejecting ink to the outside by utilizing thermal expansion of bubbles generated by electrolysis of conductive water-based ink.

[0002]

2. Description of the Related Art As a conventional ink jet recording apparatus of this type, for example, an ink jet recording apparatus described in Japanese Patent Publication No. 2-50842 is known.

This ink jet recording apparatus is characterized in that it has an ink discharge port and an ink supply port and that a pair of electrodes, that is, an anode electrode and a cathode electrode, are provided in the flow path.

[0004] This technology is based on the assumption of a horizontal plane electrode pair structure, although there is no description in the publication regarding the electrode structure. This is because the horizontal plane structure is rational in implementing the technique for the following reasons.

(1) In order to improve the heat generation effect, measures are taken to make the surface area of one electrode smaller than that of the other, and the bubbles generated by electrolysis are further heated by Joule heat to cause thermal expansion of the bubbles for ink ejection. It is a so-called energization type bubble jet recording method in which the motive force is expansion, and bubbles expand and shrink rapidly with the ink around the bubbles when the energization is stopped.

(2) The essential feature of this method is that it is devised so as to avoid discharge in the generated bubbles.

[0007]

However, the above conventional ink jet recording apparatus has the following problems.

(1) The expansion / contraction of bubbles generated by electrolysis of the conductive water-based ink is introduced into the ink discharge mechanism. However, since these bubbles do not shrink and disappear, they remain in the flow path. It remains as air bubbles and hinders subsequent ink replenishment.

(2) As a means for heating and expanding the bubbles generated by electrolysis, it is assumed that Joule heat is used, but this is because the electric current in the ink is the basis, and therefore electrolysis proceeds at the same time. It will be. However, the bubble growth due to electrolysis is much faster than the bubble growth due to Joule heat, and as a result, the ink ejection pressure due to the boiling point rise cannot be expected.

It is an object of the present invention to provide an ink jet recording system which can solve the above problems and an ink jet recording apparatus which specifically realizes the system.

[0011]

According to the ink jet recording method of the present invention, an anode electrode and a cathode are provided in a channel having an ink ejection port for ejecting ink in a desired direction and an ink supply port communicating with an ink tank. In the method of arranging electrodes and controlling the voltage applied to both electrodes to realize ink ejection, the ink in the flow path is energized to generate hydrogen bubbles and the hydrogen bubbles are exposed to a strong electric field. A plasma fluid consisting of hydrogen molecules and electrons was generated between the anode electrode and the cathode electrode, and the electrons in the plasma fluid were accelerated by a strong electric field to cause thermal oscillation. As a result, hydrogen bubbles expand and are discharged outside the flow path.

In the ink jet recording method of the present invention, in the above recording method, the ink supply port is directly adjacent to the ink tank, and a capillary phenomenon is induced in the flow path, so that the plasma fluid and the ink are mixed. It was designed to be discharged outside the flow channel.

Further, the ink jet recording apparatus of the present invention has a flow path having an ink ejection port for ejecting ink in a desired direction and an ink supply port communicating with the ink tank,
In an apparatus in which an anode electrode and a cathode electrode are arranged, an insulating thin plate is arranged between the anode electrode on the ink ejection port side and the cathode electrode on the ink supply port side to adjoin both electrodes, and The openings are formed in a shape that is rotationally symmetric with respect to the central axis in the ink ejection direction.

The ink jet recording apparatus of the present invention also has a flow path having an ink ejection port for ejecting ink in a desired direction and an ink supply port communicating with the ink tank.
In an apparatus having an anode electrode and a cathode electrode, a power control unit for setting the anode electrode on the ink ejection port side to a higher potential than the cathode electrode on the ink supply port side, and for performing constant voltage drive control on both electrodes. Was established.

In the above ink jet recording apparatus, the energization area of the anode electrode is smaller than the energization area of the cathode electrode, and at least the surface portions of the anode electrode and the cathode electrode are made of gold, platinum, stainless steel, titanium alloy, or It is formed of any material of these combinations.

[0016]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is an exploded view showing the structure of a recording head section in an ink jet recording system according to an embodiment of the present invention.

Referring to FIG. 1, the recording head portion is mainly composed of an anode plate 1, a gap plate (insulating thin plate) 8 and a cathode plate 5.

The anode plate 1 is formed by forming a pattern of the anode electrode 2 in a desired shape and interval on an insulating plate having excellent discharge characteristics, and forming an opening 3 in a part thereof. Thus, the ink ejection port 4 is formed on the opposite side of the opening 3.

The cathode plate 5 is a conductor plate having excellent heat dissipation characteristics and electrochemical characteristics, and an opening 6 corresponding to the opening 3 is formed therein, and functions as a common electrode. Thus, the ink supply port 7 is formed on the opposite side of the opening 6.

The gap plate 8 has a similar opening 9 formed on an insulating plate having excellent heat resistance. By laminating the opening 9 with the anode plate 1 and the cathode plate 5 from both sides, Opening 3,
9 and 6 communicate. Therefore, a circular tubular path from the ink ejection port 4 to the ink supply port 7 is formed, and the anode electrode 2 and the cathode plate 5 are close to each other in the flow path via the gap plate 8. The cathode plate 5 functions as a cathode electrode.

When the ink tank 10 having a hollow solid shape such as a box shape is assembled so as to be covered with the cathode plate 5, the ink supply port 7 is directly adjacent to the ink tank 10. Therefore, ink can be supplied into the flow path from the ink tank 10 through the ink supply port 7 to the ink ejection port 4 by the action of the capillary phenomenon.

Further, the processing of the above-mentioned openings 3, 9 and 6 is
Since the electrode shape inevitably has a ring shape in the flow path, it is not only rotationally symmetrical with respect to the central axis in the ink ejection direction, but also of high dot density flow path and multiple flow paths for colorization are formed. Sometimes mass production can be expected.

FIG. 2 is a system diagram of a head control unit for controlling the above-mentioned recording head unit. Referring to this figure, when the data buffer 13 is full of data, the buffer busy signal 10 is sent to the recording device main body control unit 11 via the I / O bus 12.
Returns 1 to indicate that data cannot be received.

On the contrary, when the buffer busy signal 101 is inactive, it is considered that the data buffer 13 is in a receivable state, and the data signal is transferred from the recording device main body control section 11 via the I / O bus 12. Then, the data buffer 13 is stacked in the FIFO mode.

On the other hand, as long as there is data in the data buffer 13, the buffer ready signal 103 becomes active, during which the flow path selection signal generator 14 operates. The flow path selection signal generator 14 outputs the pulse width control signal 104 for all drive flow paths in a fixed sequence.

The pulse width control signal 104 is input to the switch circuit 15 composed of a decoder or a multiplexer or the like, selects the data signal 102 to the corresponding drive flow path, and outputs it to the level conversion circuit 16 as the head drive instruction signal 105. Transferred.

The level conversion circuit 16 converts the head drive instruction signal 105 as a digital control level signal into a constant voltage head drive level signal 106 as an analog control level signal.
Convert to. The head drive level signal 106 means a constant voltage level sufficient to generate a plasma (described later) by discharging between the anode electrode and the cathode electrode, and this value is generally determined by the atmosphere of the plasma generation space.

However, since electrolysis (described later) by energizing the ink in the flow path of the recording head portion 18 is performed by current control, the current amplification circuit 17 having the function of the output impedance conversion of the level conversion circuit 16 is configured. To do. Therefore, the output is the recording head unit 18 as a head drive signal 107 having a constant voltage and a required current capacity.
It becomes possible to supply power to.

FIG. 3 is an operation principle diagram for stepwise explaining the operation principle of the ink jet recording system of the present invention based on a physical phenomenon.

FIGS. 3 (a) and 3 (b) are models of bubbles due to electrolysis when the aqueous ink is energized, particularly hydrogen bubbles 21 and oxygen bubbles 22. That is,
Hydrogen bubbles 21 are generated from the cathode electrode 5 side, and oxygen bubbles 22 are generated from the anode electrode 2 side. These bubbles 21,22
First, as shown in FIG. 3 (a), they are generated in a string of beads, but thereafter, as the bubbles 21 and 22 grow, finally, as shown in FIG. 3 (b), hydrogen is the main component. Becomes a single bubble 23.

FIGS. 3C and 3D show the hydrogen bubble 23.
This is a model of a state in which hydrogen molecules 25 inside are ionized to generate plasma. That is, initial electrons and the like of the cathode electrode 5 are accelerated by the external electric field, and the following reaction occurs.

H ₂ + (-) → H ₂ ⁺ + (2-) By repeating this reaction, the electrons 24 are rapidly propagated and pulled by the Coulomb attractive force toward the anode electrode 2 side, and Boltzmann distribution is exhibited between the electrodes. Plasma fluid 2
6 is realized. Therefore, the change in ink state can be modeled as follows.

Liquid → Gas → Plasma As described above, the present embodiment has a unique idea from the prior art that the hydrogen bubble 23 obtained by electrolysis of ink and Joule heat of ink is used as a means for ejecting ink. And

FIG. 3 (e) is a model of how the electrons that make up the plasma oscillate.

That is, the Boltzmann-distributed electron plasma 2
The case 6 is in the equilibrium state with the hydrogen molecule ions, in other words, the case where the temperature of each plasma particle is the same.
However, since the electron 24 has a smaller mass than the hydrogen molecule 25, an electrostatic attraction due to an external electric field or a Coulomb attraction between plasma particles causes thermal oscillation with a large amplitude,
The hydrogen molecule 25 is almost stationary. Therefore, only the electrons 24 collide with the ink wall surface to raise the temperature of the ink surface, and thereafter, the volume expansion of the plasma fluid 26 is induced, leading to ink ejection.

To simply express the above phenomenon, hydrogen bubbles generated by electrolysis are isothermally expanded by thermal vibration of electrons (plasma). The thermodynamic work at this time is used as a driving force for ink ejection, which is the essence of the inkjet recording system of the present invention.

FIG. 3 (f) is a model of the ink ejection state. That is, the plasma fluid 26 and the ink on the ink ejection port side of the plasma fluid 26 are both discharged outside the flow path. The ejected ink becomes ink dot droplets 28 due to the surface tension thereof and flies toward the recording paper.

On the other hand, the plasma fluid 26 is discharged to the outside of the flow path when the replenishment ink from the ink tank 10 is re-inked into the flow path by the capillary phenomenon. It is considered that the plasma fluid 26 becomes hydrogen gas or water vapor due to rapid recombination and the like when the discharge is stopped. Therefore, when these remain in the flow channel, they cannot be eliminated by a cooling effect or the like like a heat bubble. Therefore, the plasma fluid 26 is also discharged outside the flow path.

Next, referring again to FIG. 3C, the direction of the electric field will be referred to.

When the cathode electrode 5 is biased at a higher potential than the anode electrode 2, plasma is generated in the vicinity of the cathode electrode 5 and the ink wall surface on the ink tank 10 side is heated to realize volume expansion. That is, although the ink can be ejected, the ejection force for the ink on the ejection nozzle side is indirectly transmitted via the bubbles. Therefore, in order to make the anode electrode 2 have a higher potential than the cathode electrode 5,
It is advantageous to design the head drive level signal 106 of FIG.

Furthermore, in plasma vibration, the vibration energy increases as the ambient temperature increases. That is, the current-carrying area of the anode electrode 2 is made smaller than that of the cathode electrode 5 in order to effectively utilize the Joule heat generated in the electrolysis process in order to raise the temperature of the hydrogen bubble 23 in FIG. 3B. As a result, the current density during electrolysis increases near the anode electrode 2, and the temperature rise of the generated hydrogen bubbles 23 can be expected.

Further, the relationship between the ink and the electrodes will be described.

The ink having the electricity-carrying property is generally an electric field solution, and a solvent may be deposited on the surface of the electrode, or the electrode itself may be ionized to be consumed greatly. Such problems result from the chemical reaction characteristics of the electrode material. Therefore, it is desirable to use gold, platinum, stainless steel, titanium alloy or the like, which is a non-electrolyte and poorly reactive material for the electrode.

The cathode electrode 5 as the common electrode may be made of a stainless steel plate, and the anode electrode 2 as the pattern electrode may be made of platinum (including plating).

[0046]

As described above, according to the present invention,
It has the following excellent effects.

(1) Since the anode electrode and the cathode electrode are close to each other, discharge plasma oscillation can be generated at a relatively low applied voltage.

(2) The potential distribution in the electric field bubble can be approximately linearized by making the openings of the respective electrodes symmetrical with respect to the central axis of the flow path, in particular, rotationally symmetrical.

(3) Since the electric field bubbles are used, the responsiveness is superior to that of the thermal bubbles and the discharge start voltage in the hydrogen bubbles is lower than that in the other gases, so that a relatively low voltage is applied. The voltage can cause discharge plasma oscillation.

(4) Since the ink wall surface is heated by utilizing the thermal vibration of electrons, only the state change occurs with respect to a minute amount of ink, and it is necessary to consider the temperature rise and deterioration due to the heat of the ink and the electrode. There is no.

(5) Since the plasma fluid is discharged together with the ink to the outside of the flow path, there is no need for a bubble contraction process as in the bubble jet recording system, and therefore, the flow path, especially to the electrodes, is not required. There is no need for cavity erosion countermeasures.

(6) By setting the anode electrode at a higher potential than the cathode electrode, a strong plasma space is formed in the vicinity of the former, and the plasma vibration energy at that time can be directly transmitted to the ejected ink.

(7) By making the conducting area of the anode electrode smaller than that of the cathode electrode, it is possible to realize the temperature of the electric field bubble which is not influenced by the external environment. Moreover, by using a non-electrolyte such as gold, platinum, stainless steel, and titanium alloy as the electrode material and a chemically stable metal, it is possible to prevent deterioration of the ink and clogging due to the deterioration.

These effects eventually contribute to steady ink ejection.

[Brief description of drawings]

FIG. 1 is an exploded view showing a configuration of a recording head unit in an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a control system diagram of a recording head unit according to the present embodiment.

FIG. 3 is an operation principle diagram relating to the inkjet recording method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Anode plate 2 ... Anode electrode 3,6,9 ... Opening part 4 ... Ink discharge port 5 ... Cathode plate 7 ... Ink supply port 8 ... Gap plate 10 ... Ink tank 11 ... Recording device main body control part 12 ... I / O Bus 13 ... Data buffer 14 ... Flow path selection signal generator 15 ... Switch circuit 16 ... Level conversion circuit 17 ... Current amplification circuit 18 ... Recording head unit 19 ... Recording head control unit (electric power control means) 21, 23 ... Hydrogen bubble 22 ... oxygen bubbles 24, 27 ... electrons 25 ... hydrogen molecules 26 ... plasma fluid 28 ... ink dot drops 101 ... buffer busy signal 102 ... data signal 103 ... buffer ready signal 104 ... pulse width control signal 105 ... head drive instruction signal 106 ... head Drive level signal 107… Head drive signal

Claims (6)

[Claims] 1. An anode electrode and a cathode electrode are arranged in a flow path having an ink ejection port for ejecting ink in a desired direction and an ink supply port communicating with an ink tank, and applied to both electrodes. In an ink jet recording method that realizes ink ejection by controlling a voltage, the ink in the flow path is energized to generate hydrogen bubbles, and the hydrogen bubbles are placed in a strong electric field and the anode electrode and the cathode electrode are placed. An ink jet recording method characterized in that a plasma fluid composed of hydrogen molecules and electrons is generated between and, and further, electrons in the plasma fluid are accelerated by a strong electric field to cause thermal oscillation. 2. The ink jet recording system according to claim 1, wherein the ink supply port is directly adjacent to the ink tank, and a capillary phenomenon is induced in the flow channel, thereby causing the plasma fluid to flow outside the flow channel together with the ink. The inkjet recording method is characterized in that the ink is discharged to the inside. 3. An ink jet recording apparatus in which an anode electrode and a cathode electrode are arranged in a flow path having an ink ejection port for ejecting ink in a desired direction and an ink supply port communicating with an ink tank. , An insulating thin plate is placed between the anode electrode on the ink ejection port side and the cathode electrode on the ink supply port side to adjoin both electrodes, and the openings of each electrode rotate relative to the central axis in the ink ejection direction. An inkjet recording apparatus, which is formed in a symmetrical shape. 4. An ink jet recording apparatus in which an anode electrode and a cathode electrode are arranged in a flow path having an ink ejection port for ejecting ink in a desired direction and an ink supply port communicating with an ink tank. An ink jet recording apparatus characterized in that an anode electrode on the ink ejection port side has a higher potential than a cathode electrode on the ink supply port side, and a power control means for controlling constant voltage driving of both electrodes is provided. 5. The ink jet recording apparatus according to claim 4, wherein the energization area of the anode electrode is smaller than the energization area of the cathode electrode. 6. The method according to claim 3, wherein at least the surface portions of the anode electrode and the cathode electrode are made of any material of gold, platinum, stainless steel, titanium alloy, or a combination thereof. 5. The inkjet recording device according to item 5.