JP2772733B2 - Ink jet recording device - Google Patents

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 apparatus utilizing an air flow for recording characters, figures and the like by discharging ink from minute openings.

[0002]

2. Description of the Related Art There are various types of ink jet recording apparatuses, and some apparatuses utilizing an air flow have been proposed. Hereinafter, this type of conventional ink jet recording apparatus will be described with reference to the drawings. FIG. 4 shows a configuration of a conventional ink jet recording apparatus using an air flow and an electrostatic force. In FIG. 4, 1 is an air nozzle plate, 2 is an air discharge port, 3 is an ink nozzle plate, 4 is an ink discharge port,
Is a body member, 6 is an air chamber, 7 is an air flow path, 8 is an air supply pipe, 9 is an ink chamber, 10 is an ink supply pipe, and 11 is formed around the ink ejection port 4 on the back surface of the ink nozzle plate 3. A first electrode 12 is a second electrode formed around the air discharge port 2 on the surface of the air nozzle plate 1, and 13 is a first electrode 11 and a second electrode 11.
These are signal sources connected between the electrodes 12 and constitute an ink jet head 14. Reference numeral 15 denotes an ink tank for supplying ink into the ink chamber 9 through the ink supply pipe 10, 16 denotes an air supply source for supplying air into the air chamber 6 through the air supply pipe 8,
Reference numeral 17 denotes a branch pipe provided in the middle of the air supply path, and reference numeral 18 denotes a pressure regulator provided in the middle of the branch pipe 17 for adjusting the ink pressure in the ink tank 15.

In the above conventional example, the air discharge port 2 and the ink discharge port 4 are opposed to each other. From the air discharge port 2, air at a constant flow rate flowing from the air chamber 6 through the air flow path 7 flows out. I have. When a potential difference is applied from the signal source 13 between the first and second electrodes 11 and 12 provided on the front surface of the air discharge port 2 and the back surface of the ink discharge port 4, the ink held in the ink discharge port 4 is discharged. The ink is drawn out, flies while being accelerated by the air flow through the air discharge port 2, and adheres to the recording paper disposed in front to perform recording.

The air in the air chamber 6 is supplied from an air supply source 16, and the air from the air supply source 16 is sent to an ink tank 15 via a pressure regulator 18 on the other hand. Pressure is applied to the ink to balance the pressure of the ink in the ink discharge port 4 with the pressure of the air near the ink discharge port 4 so that the ink discharge port 4 stably holds the meniscus of the ink. It is set so that ink is ejected only when a corresponding electrostatic force is generated. That is, if the pressure of the ink tank 15 is too high, the pressure of the ink in the ink discharge port 4 also increases, and the ink spontaneously discharges even when no electrostatic force is generated,
On the other hand, if it is too low, the air flow will flow into the ink ejection port 4 and the ink cannot be supplied. Therefore, the pressure adjuster 18 adjusts the ink pressure in the ink tank 15 so that the ink is held in the ink discharge ports 4 and a meniscus is generated in a stable shape by the action of the surface tension.

FIG. 5 shows a conventional example of the pressure regulator 18 shown in FIG. In general, as a method of adjusting the pressure, a method is employed in which a certain amount of pressure drop is caused by a pressure loss due to the flow of air by using the viscosity of a fluid to reduce the pressure by a certain value, as shown in FIG. In an inkjet recording device,
The ink tank 15 has a closed system, and the flow of air in the piping system led to the ink tank 15 occurs only when the air supply source 16 is turned on and off. Therefore, in such an ink jet recording apparatus, air from the air supply source 16 is supplied to the leak valve 19 as shown in FIG.
A mechanism that reduces the airflow to the ink tank 15 by allowing a part of the air to escape to the outside air and adjusts the ink pressure in the ink tank 15 has been adopted.

[0006]

However, in the above-mentioned conventional configuration, when the capacity of the ink tank 15 is large, when the air supply source 16 is turned on and off, the pressure of the air flow sent to the ink jet head 14 and the ink tank Fifteen
In some cases, the balance of the internal pressure is lost, and the above-described spontaneous ejection and air flow into the ink ejection port 4 may occur. This is because the capacity of the ink tank 15 is large, so that a time delay occurs between the application and release of the pressure to the ink.
That is, although the air sent to the inkjet head 14 has already been released, the air pressure in the ink tank 15 still remains, and the pressure is now being released by the leak valve 19. Things happen. In addition, the conventional pressure regulator 1
8, the pressure is adjusted by releasing the airflow to the outside air, so that power is required for the air supply source 16 and the size of the air supply source 16 is increased. Furthermore, it is difficult to make the leak valve 19 itself a small part, which has been one obstacle in integrating the inkjet recording apparatus into a compact form.

The present invention solves the above-mentioned problems of the prior art. Even when the air supply source is turned on and off, the pressures in the ink jet head and the ink tank are balanced, and the air supply source and the entire ink jet recording apparatus are used. An object of the present invention is to provide an ink jet recording apparatus that can be downsized.

[0008]

In order to achieve the above object, the present invention controls the pressure of air by changing the cross-sectional area of an air flow path in an air supply path from an air supply source to an ink jet head. A pressure regulator is provided to supply the air passing through the pressure regulator to the ink jet head, and to supply the air whose pressure has been regulated to the ink tank.

[0009]

According to the above construction, the air flow velocity in a small cross-sectional area is increased and the pressure is reduced by using the principle of atomization or Bernoulli's theorem, and the air flow path in the pressure regulator is cut off. By controlling the area, the pressure in the ink jet head and the pressure in the ink tank can be balanced, and the air is not leaked to the outside air, so that the air can be used efficiently, and a small and inexpensive ink jet recording apparatus is realized. be able to.

[0010]

【Example】

Embodiment 1 Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view showing a partial configuration of an ink jet recording apparatus according to a first embodiment of the present invention. In FIG. 1, 21 is an air nozzle plate, 22 is an air discharge port, 23 is an ink nozzle plate, 24 is an ink discharge port, 25 is a body member, 26 is an air chamber, 27 is an air flow path, 28 is an air supply pipe, 29 is an ink chamber, 30 is an ink supply pipe, 31 is a first electrode formed around the ink discharge port 24 on the back of the ink nozzle plate 23, and 32 is formed around the air discharge port 22 on the surface of the air nozzle plate 21. The second electrode 33 is a signal source connected between the first electrode 31 and the second electrode 32, and these constitute an ink jet head. Reference numeral 35 denotes an ink tank for supplying ink into the ink chamber 29 through the ink supply pipe 30. Reference numeral 36 denotes a pressure regulator provided in an air supply path between the air supply source 37 and the ink head 34. The air from the source 37 is supplied into the air chamber 26 through the air supply pipe 28 of the inkjet head 34, and the air whose pressure is controlled is supplied to the ink tank 35 through the branch pipe 38.

In the above embodiment, the air discharge port 22 and the ink discharge port 24 face each other,
From 2, air at a constant flow rate flowing through the air flow path 27 flows out of the air chamber 26. First and second electrodes 3 provided on the surface of the air discharge port 22 and the back of the ink discharge port 24
When a potential difference is applied between the signal source 33 and the signal source 32, the ink held in the ink discharge port 24 is drawn out, and the ink flies while being accelerated by the air flow through the air discharge port 22, and is arranged in front. The recording is performed by adhering to the recorded recording paper.

FIG. 2 is a sectional view of the pressure regulator 36 according to one embodiment of the present invention. In FIG. 2, 41 is an air inlet, 42 and 43 are air outlets, 44 and 45 are air supply chambers, 46 is a thin layer channel, 47 is a diaphragm, and 48 is a pressure adjusting screw. Air from the air supply source 37 flows in from the air inlet 41, and flows from the air supply chamber 44 to the thin layer flow path 46.
It is led to. An air outlet 42 is provided in the thin layer flow path 46 in the orthogonal direction, and pressure is applied to the ink tank 35 through the branch pipe 38. The air sent to the air supply chamber 45 through the thin layer flow path 46 is guided from the air outlet 43 to the air chamber 26 through the air supply pipe 28 of the inkjet head 34.

In such a pressure regulator 36, when air from the air supply source 37 is supplied to the air supply chamber 44 and passes through the thin layer flow path 46, the air flow in the air supply chamber 44 is perpendicular to the flow of air. Is the cross-sectional area of S ₀ , the flow velocity of the air there is V ₀ , the pressure is P ₀ , the similar cross-sectional area in the thin layer flow path 46 is S, the air flow velocity there is V, and the pressure is P. From certain rules,

(Equation 1) Ignoring the pressure loss due to air flow,

(Equation 2) From the above equations (1) and (2), the pressure P of the thin layer flow path 46 is obtained.
Is obtained as in the following equation (3).

(Equation 3)

Equation (3) indicates that the pressure P in the thin-layer flow path 46 is
This is variable by the ratio S ₀ / S of the cross-sectional area, and indicates that control is possible. Accordingly, the diaphragm 47 is moved by the pressure adjusting screw 48 to
The pressure P can be changed by changing the cross-sectional area S of FIG.

(Embodiment 2) FIG. 3 is a sectional view of an ink jet recording apparatus according to a second embodiment of the present invention.
Reference numerals 1 to 48 correspond to the members shown in FIGS. This embodiment is different from the embodiment shown in FIG.
And an ink jet head 34, an ink tank 35, and a pressure regulator 36 shown in FIG.
The air supply pipe 28, the ink supply pipe 30, and the branch pipe 37 are omitted, and the whole is configured to be compact.

The air from the air supply source 37 flows into the air supply chamber 44 and passes through the thin layer flow path 46 to the air supply chamber 45.
The air is sent from the air outlet 43 to the air chamber 26 of the inkjet head 34 and flows out of the air discharge port 22. On the other hand, an air outlet 42 communicating with the ink tank 35 is provided in the middle of the thin layer flow path 46, and pressure is applied to the ink tank 35 from the air outlet 42. The pressure of the air chamber 26 of the inkjet head 34 is controlled by the air supply chambers 44 and 45.
, But the pressure in the ink tank 35 is
By adjusting the cross-sectional area of the thin-layer flow path 46 by the diaphragm 47 by turning the pressure adjusting screw 48, it is possible to realize a pressure balance that is just convenient for the inkjet head 34.

As described above, in each of the above embodiments, when the air supply source 37 is turned on and off, the air chamber of the ink jet head 34 is proportional to the air pressure in the air supply chambers 44 and 45 of the pressure regulator 36. Since the pressures in the ink tank 26 and the ink tank 35 rise and fall, a large pressure difference does not occur between the air chamber 26 and the ink tank 35, and the application and release of the air pressure can be performed without breaking the pressure balance.

[0018]

As described above, according to the present invention, an air supply path from an air supply source to an ink jet head is provided with a pressure controller for controlling the air pressure by varying the cross-sectional area of the air flow path. The air that has passed through the pressure regulator is supplied to the ink jet head, and the air whose pressure is controlled is supplied to the ink tank, so that the pressure can be adjusted without releasing the air flow to the outside air. Therefore, a small and inexpensive air pump can be used as an air supply source. In addition, supply of pressure when the air supply source is turned on and off,
Since the release is performed at the same time in the ink jet head and the ink tank, the transient collapse of the pressure balance is eliminated,
It is possible to realize an excellent ink jet recording apparatus capable of always performing stable ink ejection.

[Brief description of the drawings]

FIG. 1 is a partial schematic cross-sectional configuration diagram of an ink jet recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a pressure regulator according to the first embodiment of the present invention.

FIG. 3 is a sectional view of an ink jet recording apparatus according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a partial cross section of a conventional ink jet recording apparatus.

FIG. 5 is a schematic diagram of a pressure regulator in a conventional inkjet recording apparatus.

[Explanation of symbols]

 21 air nozzle plate 22 air discharge port 23 ink nozzle plate 24 ink discharge port 25 body member 26 air chamber 27 air flow path 28 air supply pipe 29 ink chamber 30 ink supply pipe 31 first electrode 32 second electrode 33 signal source 34 inkjet Head 35 Ink tank 36 Pressure regulator 37 Air supply source 38 Branch pipe 41 Air inlet 42,43 Air outlet 44,45 Air supply chamber 46 Thin layer channel 47 Diaphragm 48 Pressure adjusting screw

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/045

Claims (3)

(57) [Claims] An air discharge port is provided to face an ink discharge port holding ink, a constant air flow is caused to flow out from the air discharge port, and an electrode is provided around the ink discharge port and the air discharge port. An ink jet head that ejects the ink in the ink ejection ports through the air ejection ports by applying a signal to the ink jet head, an ink tank that supplies ink to the inkjet head, and an air supply source that supplies air to the inkjet head. A pressure regulator that is provided in an air supply path that communicates the inkjet head with an air supply source and controls air pressure by varying the cross-sectional area of the air flow path. Supplying air to the ink jet head and supplying pressure-controlled air to the ink tank; Ink jet recording device. 2. A pressure regulator comprising: an air inlet, an air supply chamber, a thin-layer flow path, an air supply chamber, an air flow outlet, and an air supply chamber arranged in a direction from the air supply source toward the ink jet head; 2. The diaphragm according to claim 1, further comprising a diaphragm for varying the area, a pressure adjusting screw for adjusting a pressing force applied to the diaphragm, and an air outlet communicating with the ink tank so as to be orthogonal to the thin layer flow path. Ink jet recording device. 3. The ink jet recording apparatus according to claim 1, wherein the ink jet head, the ink tank, and the pressure regulator are integrally formed.