JPH10138506A - Ink jet recording apparatus and valve mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable ink jet recording apparatus by preventing trouble such as the fixing of a sub-tank film or the clogging of a passage even when a circulating type ink jet recording apparatus is allowed to stand over a long period of time. SOLUTION: A flexible supply tube 51 is connected to the ink supply port 7 on the side of a cartridge 41 and a passage valve 52 being a valve means is connected to the other end of the supply tube 51. The passage valve 52 is further connected to an ink cartridge 41 through a tube 54 and a tubular needle 53. An air pump 61 serving as an ink supply means is branched into four systems through a pressure regulator 62 to be connected to the ink cartridge 41 from changeover valves 63 through air pipes 64.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus having an ink jet head for ejecting ink droplets only when recording is required and attaching the ink droplets to recording paper.

More specifically, a circulating system in which an ink jet recording head and a sub-tank are mounted on a carriage, and recording is performed while supplying ink to the sub-tank and the recording head via a flow path from an ink cartridge installed in a box. Related to inkjet recording devices.

[0003]

2. Description of the Related Art An ink jet recording apparatus mounts an ink jet recording head for ejecting ink droplets by a pressure generating means on a carriage and performs printing while receiving ink supply from an ink tank. An ink cartridge is also mounted on a carriage to simplify the structure.

On the other hand, with the improvement in the performance of the ink jet recording head, the dot density has increased dramatically, and color printing with a natural color has become possible. Efforts have been made to minimize the bleeding of the skin.

[0005] As one of the means, there has been proposed a method in which an emulsion made of a thermoplastic resin or sugar is contained in the ink, and the discharged ink is heated on a recording medium to form a film.

[0006] Ink having such a film forming property has the advantage that the image quality is greatly improved due to very little bleeding, and the emulsion in the ink is melted and fixed by heating. While having the advantage of obtaining water resistance, the concentration of solids in the ink composition is high, and is further affected by heat from heating means,
Unstable discharge is likely to occur due to an increase in the viscosity of the ink or the generation of bubbles due to the temperature rise.

As a method of solving such a problem,
It has also been proposed to circulate the ink by connecting the printhead, sub-tank, and ink cartridge endlessly. However, there are two flow paths between the printhead and the ink cartridge: a forward flow path and a return flow path. Since a flow path is required, there is a problem that the flow path structure is complicated. The present applicant has two common ink chambers communicating with both sides of the pressure chamber of the recording head, and an ink supply port through which ink flows into each common ink chamber from the outside, and one of the ink supply ports is provided. The sub-tank and the other ink supply port are connected to the ink cartridge, and ink is pumped into the sub-tank via an ink jet recording head by ink supply means for pressure-feeding the ink in the ink cartridge, and the recording head is also discharged from the sub-tank. An ink jet recording apparatus has been proposed in which printing is performed while circulating the ink inside the recording head by flowing the ink back to the ink cartridge via the ink cartridge.

According to this, without increasing the complexity of the structure, it is possible to prevent the increase in viscosity of the recording head and the temperature of the recording head as much as possible, and to perform stable recording.

[0009]

The sub-tank is made of a flexible film, so that pressure fluctuation is extremely small.
Furthermore, since the circulation can be performed without foaming even by the vibration of the carriage accompanying the recording operation, there is an excellent merit that more stable recording can be performed.

However, in the non-operating state, the ink in the sub-tank flows back toward the ink cartridge due to the difference in gravity, so that the films are in close contact with each other via a slight ink layer. In this state, when moisture evaporates through the flexible film when left for a long time or the like, the concentration of the solid content in the remaining ink significantly increases, and the films are fixed to each other or the sub-tank reaches the head. There is a problem that the ink in the flow path up to the solidification causes a trouble such as clogging.

The present invention has been made in view of such a problem, and an object of the present invention is to allow ink to remain in a sub-tank even in a non-operating state, so that even if the ink is not used for a long period of time, an obstacle is caused. An object of the present invention is to provide an ink jet recording apparatus which does not cause the problem.

[0012]

For this purpose, in the present invention, two common ink chambers communicating with both sides of the pressure generating chamber are provided, and each of the common ink chambers is provided with an ink supply port connected to the outside. An ink jet recording head and a subtank mounted on a carriage, and an ink cartridge provided outside the carriage and connected to the ink jet recording head by a flow path; and an ink supply unit for pressure-feeding the ink of the ink cartridge. In a recording apparatus, a valve means is provided between the recording head and the ink cartridge.

Further, the valve means is a normally closed type solenoid valve.

Further, the invention is characterized in that the valve means operates in accordance with the pressure of the ink supply means for pressure-feeding the ink.

Further, in the valve mechanism, the ink supply means for pressure-feeding the ink is an air pump, and the diaphragm is connected to the air pump by a flow path, and is disposed inside a flow path between the recording head and the ink cartridge. And the valve member is displaced in conjunction with the displacement of the diaphragm.

Further, the valve mechanism is characterized in that a plurality of valve members are provided for a single diaphragm.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of the flow path of the ink jet recording apparatus of the present invention, and FIG. 2 shows the structure of the ink jet recording apparatus of the present invention. FIGS. 3 and 4 are structural views of a subtank portion and an ink cartridge portion used in the present invention, respectively.

In FIG. 2, the recording head 1 and the sub-tank unit 30 are locked on the carriage 2 and perform reciprocating scanning by driving means (not shown) (main scanning). On the other hand, a platen 10 disposed at a position facing the recording head 1 is rotated by a driving unit (not shown), and conveys recording paper 12 as a recording medium in one direction (sub-scan). In synchronization with the main scanning and the sub-scanning, ink droplets are ejected from the recording head 1 based on the recording data, and adhere to the recording paper 12 to perform predetermined recording.

The ink droplets recorded on the recording paper 12 receive heat supply from a platen 10 heated by a heater 11 as a heating means, and water in the ink is rapidly evaporated and contained in the ink. The surface of the emulsion, which is a thermoplastic resin, is melted and bonded to prevent bleeding on the paper surface and impart water resistance.

At this time, heat is also transmitted to the recording head 1 facing the platen 10, but this heat is cooled by flowing ink inside the recording head 1 (ink circulation) in addition to cooling by an exhaust fan (not shown). Is done.

Next, the flow path configuration of the ink jet recording apparatus of the present invention will be described with reference to FIG. In the present embodiment, color printing is performed using four color inks. However, air from a single air pump is branched into four systems and ink circulation is performed for each system. Only one of them is shown.

A sub-tank 32 is connected to the recording head 1. The recording head 1 has two common ink chambers 4 and 5 communicating with both sides of the pressure chamber 3 and ink supply ports 6 and 7 into which ink flows from the outside into each common ink chamber. One ink supply port 6 is located on the sub tank 32 side, and the other ink supply port 7 is located on the ink cartridge 4 side.
Connected to the first side, the ink flows (ink circulation) via the pressure chamber according to the pressure difference generated between the ink chambers.

A flexible supply tube 51 is connected to the ink supply port 7 on the cartridge 41 side.
The other end of 1 is connected to a flow path valve 52 as a valve means. The flow path valve 52 of this embodiment is a so-called normally closed type solenoid valve having a characteristic that the flow path is opened by energizing an internal solenoid and the flow path is shut off in a non-energized state.

The flow valve 52 is further connected to the ink cartridge 41 via a tube 54 and a tubular needle 53.

An air pump 61 serving as an ink supply means is branched into four systems via a pressure regulator 62, and is connected to the ink cartridge 41 via a switching valve 63 via an air pipe 64.

Next, the recording operation will be described and will be described in further detail.

At the start of the recording operation, the flow path valve 5
2 and the flow path is opened to operate the air pump 61.

Thereafter, the ink circulation operation is started based on the amount of ink in the sub tank.

The structure of the sub-tank unit 30 is shown in an exploded view in FIG. The sub tank 32 is made variable in capacity by using a flexible film. 141 is the sub tank 3
2 is an ink full detector for detecting ink full,
Reference numeral 42 denotes an ink low detector for detecting ink empty. Ink full is detected when the tip of the detection plate 140, which is a plate-like spring, disposed along the surface of the sub-tank 32 blocks the optical axis of the ink-full detector 141 composed of a light emitting and receiving element pair. You. Also,
The inclaw detector 142 constitutes the optical axis of the light emitting and receiving element pair with the sub-tank 32 interposed therebetween. The ink inside the sub-tank 32 having light transmittance decreases, and the amount of transmitted light increases, so that the ink empty in the sub-tank increases. Is detected.

When the ink full state of the sub tank is detected, the power supply to the switching valve 63 is turned off by a control circuit (not shown). The switching valve 63 is a so-called three-way valve that is opened when the power is turned off, and the air pump 61 is shut off when the power is turned off, and the cartridge side is connected to the atmosphere. Therefore, the atmospheric pressure is communicated to the connected ink cartridge.

As shown in a sectional view of FIG. 4, the ink cartridge 41 has a structure in which an ink bag 43 is housed in an airtight box 42 and an air pipe 64 is connected to an air port of the box 42. Therefore, when the inside of the box 42 becomes atmospheric pressure,
Since the ink in the ink bag 43 becomes as equal as possible to the atmospheric pressure, the ink in the sub-tank is supplied to the recording head with a head difference indicated by H in FIG. It is reversed.

Next, when the ink empty state of the sub tank is detected, the switching valve 63 is energized, and the box 42 of the ink cartridge is communicated with the air pump 61.

The pressure from the air pump 61 is adjusted by the action of the pressure regulator 62 so that the ink does not leak. Since the ink in the ink bag 43 is pressurized by this pressure, the ink in the ink bag 43 is supplied to the recording head and is also pumped to the sub-tank through the recording head.

Thereafter, the ink circulation is performed by sequentially repeating the above operations during the recording operation.

When a series of recording operations is completed, the following operations are performed.

First, the switching valve 63 is energized to pump ink into the sub-tank 32, and when the ink in the sub-tank is detected, the energization to the flow path valve 52 is turned off.
F, the flow path between the recording head and the ink cartridge is shut off. Therefore, ink is stored inside the sub tank 32.

According to this, even if the ink is left in the sub-tank for a long period of time, even if the ink in the sub-tank evaporates, the increase in the solid concentration is reduced, and thus the clogging is prevented. And the films are effectively prevented from sticking to each other.

Further, since the flow path valve serving as the valve means is a normally closed type solenoid valve, the flow path is cut off even when the power is cut off due to an unexpected reason such as a power failure during the recording operation. In addition, there is an effect that ink is held in the sub tank.

Also, when the printing operation is restarted, the sub-tank holds an amount of ink equivalent to the ink full state, so that the printing operation can be started immediately.

(Other Embodiment) FIG. 5 shows a flow path configuration of an ink jet recording apparatus according to a second embodiment of the present invention.
FIG. 6 shows the structure of the valve means.

Hereinafter, description will be made with reference to the drawings.

FIG. 6A is an exploded view showing the structure of the flow path valve 52 used in this embodiment.

In the embodiment, four channels are arranged in a single unit, and the same operation is performed for each channel. Reference numeral 154 denotes a valve whose shaft portion is slidably supported by the casing 156, and which is urged by a spring 153 in a normal state to be packed.
4 is pressed. A spring 15 is provided on the upper part of the casing 156.
3 having a function of fixing the tube 3 and connecting it to the tube 51
51 is fixed. In addition, a connection port with the tube 54 communicating with the ink cartridge is formed integrally with a lower portion of the casing 156. A flexible film 157 is disposed in the lower opening of the casing 156 so as to form a clearance (indicated by c in FIG. 6B) with respect to the operating shaft of the valve 154.
The flexible film may be made of rubber or the like, but in this embodiment, the flexible film is a laminated film obtained by joining a polyethylene film, which is a thermoplastic resin, to a film obtained by depositing aluminum on a PET film. Was used. According to this, it can be joined to the casing 157 by heat welding, and is more effective in preventing permeation of moisture or intrusion of air. As described above, the ink flow path is formed. However, since the ink flows upward from below as shown by “a” in the drawing due to pressurization, it is preferable because no gas remains in the flow path valve 52. Plastic film 157
A cover 159 is disposed below the cover 159 via a diaphragm 158 made of a rubber material and integrally formed with a pressure receiving portion 161 to form a chamber 160. Cover 15
9, an air port to the chamber 160 is integrally formed. The air port is connected to a branch plate 66 via a bypass pipe 65 as shown in FIG.

Next, the operation of the flow path valve in this embodiment will be described.

While the air pump 61 serving as the ink supply means is stopped, the inside of the chamber 160 is maintained at the atmospheric pressure, and the operating shaft of the valve 154 urged by the spring 153 maintains the clearance with the flexible film 157. Therefore, the ink flow path is shut off. FIG. 6B is a sectional view showing this state.

Next, when the air pump 61 operates,
The inside of the chamber 160 is pressurized, and the diaphragm 158 is evenly loaded by the pressure. This equal load is applied to the pressure receiving unit 1
The diaphragm 158 is displaced by the urging force according to the area of the spring 61 and is urged to the operating shaft of the valve 154 via the flexible membrane 157. The valve 154 moves upward against the urging force of the spring 153, and Road is opened. The state at this time is shown in FIG.
FIG.

Therefore, at the start of the recording operation, the flow path is opened only by operating the air pump 61, and the ink can be circulated. When the recording operation is completed, the air pump 61 is stopped to shut off the flow path between the recording head and the ink cartridge.

Thus, according to the above configuration, the valve means can be operated in accordance with the pressure of the ink supply means, whereby the ink can be stored in the sub-tank even in a non-operating state.

In addition, there is an effect that a plurality of flow passage valves can be integrally formed, and thus can be formed at a lower cost.

[0051]

According to the present invention, by arranging valve means in the flow path between the recording head and the ink cartridge, ink can be stored in the sub tank.
Therefore, even when left for a long period of time, it is possible to effectively prevent sticking of the films and clogging of the flow path.

[Brief description of the drawings]

FIG. 1 is a diagram showing a flow path configuration of an ink jet recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the structure of the ink jet recording apparatus according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a structure of a sub tank used in the first embodiment of the present invention.

FIG. 4 is a sectional view of an ink cartridge used in the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a flow path configuration of an ink jet recording apparatus according to a second embodiment of the present invention.

FIG. 6 is a view for explaining the configuration of valve means used in the second embodiment.

FIG. 7 is a diagram illustrating a configuration of a conventional inkjet recording apparatus.

[Explanation of symbols]

 1: recording head 2: carriage 3: pressure chambers 4, 5: ink chambers 6, 7: supply port 10: platen 11: heater (heating means) 12: recording paper (recording medium) 32: sub tank 41: ink cartridge 51: Supply tube 52: Flow path valve (valve means) 61: Air pump (ink supply means) 154: Valve 157: Flexible membrane 158: Diaphragm 160: Chamber

Claims (5)

[Claims] An ink jet recording head and a sub-tank having two common ink chambers communicating with both sides of a pressure generating chamber, and an ink supply port connected to the outside of each of the common ink chambers are mounted on a carriage. An ink cartridge connected to the ink jet type recording head by a flow path outside the carriage; and an ink supply unit for pressure-feeding the ink of the ink cartridge. An ink jet recording apparatus, further comprising a valve means. 2. An ink jet recording apparatus according to claim 1, wherein said valve means is a normally closed type solenoid valve. 3. An ink jet recording apparatus according to claim 1, wherein said valve means operates in accordance with a pressure of an ink supply means for pressure-feeding the ink. 4. An ink supply means for feeding the ink under pressure is an air pump, a diaphragm connected to the air pump by a flow path, and a valve member disposed inside a flow path between a recording head and an ink cartridge. 4. The valve mechanism according to claim 3, wherein the valve member is displaced in conjunction with the displacement of the diaphragm. 5. The valve mechanism according to claim 4, wherein a plurality of valve members are provided for a single diaphragm.