JP3351456B2 - 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 head and a sub-tank mounted on a carriage, and ink is supplied from an ink cartridge installed in a box to the sub-tank and the recording head through a flow path in a circulating manner. The present invention relates to an inkjet recording apparatus that performs recording while performing recording.

[0002]

2. Description of the Related Art With the improvement of the performance of an ink jet recording head, the dot density has increased dramatically, and color printing in a natural color has become possible. Efforts have been made to minimize the bleeding of the skin. One of the means is to make the ink contain an emulsion composed of a thermoplastic resin or sugar.
A method has been proposed in which the ejected ink is heated on a recording medium to form a film.

[0003] Inks having such film forming properties have 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, so that high water resistance is obtained. On the other hand, the ink has a high concentration of solids in the ink composition and receives heat from the heating means, so that the viscosity of the ink tends to increase. Is unstable.

In order to solve such a problem, it has been proposed to circulate the ink by connecting the recording head, the sub-tank and the ink cartridge endlessly. Because it requires two flow paths, the flow path for the return path and the flow path for the return path,
There is a problem that the flow path structure becomes complicated. In order to solve such a problem, as disclosed in Japanese Unexamined Patent Publication No. 95-031335, two communication ports on both sides of the pressure chamber of the recording head are provided.
A common ink chamber, and an ink supply port into which ink flows from the outside into each common ink chamber. One ink supply port is connected to the sub-tank, and the other ink supply port is connected to the ink cartridge. The ink in the ink cartridge is sent to the sub-tank via the ink-jet type recording head, and in this process, the bubbles of the recording head are discharged to the sub-tank, and the deep ink without bubbles from the sub-tank passes through the recording head. Proposed an ink jet recording apparatus which supplies ink to a recording head by flowing the ink back to an ink cartridge and circulates the ink for printing. According to this, it is possible to prevent a rise in the viscosity of the recording head and a rise in the temperature of the recording head as much as possible without complicating the structure, and it is possible to perform stable recording.

[0005]

However, the sub-tank is formed by forming a flexible film into a bag shape in order to absorb the pressure fluctuation of the ink accompanying the movement of the carriage and to perform stable printing. . On the other hand, in the non-operating state, the ink in the sub-tank flows back to the ink cartridge due to the gravity difference, that is, the siphon phenomenon, so that the films constituting the sub-tank are in close contact with each other via the thin ink layer for a long period of time. If left for a longer period of time in the state, moisture evaporates through the flexible film constituting the sub-tank, the solid content of the ink is concentrated, and the films adhere to each other, and the ink in the flow path from the sub-tank to the head is removed. There are problems such as solidification and clogging.

The present invention has been made in view of such a problem, and an object of the present invention is to make a sub-tank hold a printable amount of ink even in a non-operation state and leave it for a long period of time. An object of the present invention is to provide an ink jet recording apparatus capable of preventing a trouble due to the above.

[0007]

In order to achieve the above object, according to the present invention, the pressure generating chamber is connected to both sides.
Two common ink chambers and the common ink chambers.
Each has an ink supply port through which ink flows in from the outside,
An ink jet recording head for ejecting ink droplets in response to a print signal, a sub-tank made of a flexible film,
And an ink full detector that detects ink full
Sub tank unit provided with the ink jet type
Carriage with recording head and sub tank unit
Outside the carriage and below the sub tank
And the ink bag is housed in an airtight container.
Ink cartridge and the ink cartridge
Supplier that supplies ink to the sub tank unit from the
And a step, one of the ink jet recording heads
The ink supply port of the sub tank unit,
The other ink supply port is connected to the ink cartridge through valve means.
The ink supply means connected to an ink bag of the cartridge;
Before passing through the ink jet recording head
Refill the sub tank unit with ink, and
After refilling, stop the ink supply means and
The ink of the unit passes through the ink jet recording head.
When the recording operation is completed in the ink jet recording apparatus in which the recording operation is
The ink full state is detected by the ink full detector.
Until the ink is supplied to the sub tank unit.
When the ink full detector detects the ink full state, the supply of the ink is stopped, and the valve means is closed.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention. FIG. 2 shows an embodiment of the recording apparatus according to the present invention. The recording head 1 and the sub-tank unit 30 are mounted on the carriage 2 and perform reciprocal 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 described above, 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 are supplied with heat from a platen 10 heated by a heater 11 serving as a heating means, whereby water in the ink is rapidly evaporated, and the heat contained in the ink is removed. By melting and bonding the surface of the emulsion, which is a plastic resin, bleeding to the paper surface is prevented and the water resistance is enhanced. At this time, heat is also transmitted to the recording head 1 facing the platen 10, but this heat is cooled by ink flowing into the recording head 1 in addition to cooling by an exhaust fan (not shown).

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.

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 the common ink chambers 4 and 5. And one ink supply port 6 is connected to a sub-tank 32 constituting the sub-tank unit 30 and the other ink supply port 7 is connected to an ink cartridge 41. Flows cyclically via the pressure chamber 3 according to the pressure.

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 the present embodiment is constituted by a so-called normally closed solenoid valve in which 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. With such a structure, at the start of the recording operation, the flow path valve 52 is energized to open the flow path, and the air pump 61 is operated, whereby the ink is supplied to the recording head 1 cyclically.

On the other hand, the sub-tank unit 30 has a sub-tank 32 made of a flexible film as shown in FIG. 3, and its volume changes according to the amount of ink due to deformation of the film. The sub tank 32 is provided with an ink full detector 141 for detecting ink full and an ink low detector 142 for detecting ink empty.
The ink full detector 141 is composed of a pair of light emitting and receiving elements, and outputs a detection signal when a detection plate 140, which is a plate-shaped spring body disposed along the surface of the sub-tank 32, blocks the optical axis. And an incrow detector 1
Reference numeral 42 denotes a pair of light-emitting and light-receiving elements sandwiching the sub-tank 32, and is configured to output a signal when the amount of light transmitted through the sub-tank 32 having a light transmittance decreases and the amount of transmitted light increases. I have.

When the ink full state of the sub tank 30 is detected, the power supply to the switching valve 63 is turned off by a control circuit (not shown). The switching valve 63 is in communication with the air pump 61 when energized, and when not energized, the air pump 6
1 is cut off, and the cartridge 41 is configured as a so-called three-way valve that communicates with the atmosphere.

As shown in FIG. 4, the ink cartridge 41 contains an ink bag 43 in an airtight box 42 and an air pipe 64 connected to an air port of the box 42.
Thereby, when the inside of the box 42 becomes the atmospheric pressure, the ink in the ink bag 43 becomes equal to the atmospheric pressure as much as possible.
The ink in the sub-tank 30 is supplied to the recording head 1 with the head difference H shown in FIG. 1 and flows back to the cartridge 41 via the recording head 1.

Next, when the ink empty detector 142 detects that the ink in the sub tank 32 is empty, the switching valve 63 is energized and the ink cartridge 41 is turned on.
Box 42 is communicated with the air pump 61. The pressure from the air pump 61 is adjusted by a pressure regulator 62 so that the ink does not leak. The ink in the ink bag 43 is pressurized by this pressure, and the ink bag 43
Is supplied to the recording head 1 via the supply tube 51, and is also supplied to the sub tank 32 via this. Then, when the ink full detector 141 detects that the ink in the sub tank 32 is full, the power supply to the switching valve 63 is stopped, and the supply of the ink is stopped. Thereafter, during the printing operation, the above operation is repeated based on the signals from the detectors 141 and 142, and the ink is supplied cyclically.

On the other hand, when the recording operation is completed, the switching valve 63 is energized to pump ink into the sub-tank 32, and the energization of the flow path valve 52 is turned off when the ink full state of the sub-tank 32 is detected. Thereby, the flow path valve 52 shuts off the flow path connecting the recording head 1 and the ink cartridge 41. Thereby, the sub tank 3
The siphon phenomenon caused by the head difference H between the ink cartridge 2 and the ink cartridge 41 is prevented, and the ink filled in the sub tank 32 stays in the sub tank 32 without flowing back to the ink cartridge 41.

According to this, even if the sub-tank 32 is left for a long period of time, the ink equivalent to the ink remains in the sub-tank 32, so that even if the sub-tank 32 is formed, the increase in the solid concentration is reduced. Clogging and sticking of films are effectively prevented.

Further, since the flow path valve as the valve means is a normally closed type solenoid valve, the flow path is shut 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 there is an advantage that the printing operation can be started immediately.

FIG. 5 shows a second embodiment of the ink jet recording apparatus according to the present invention. In this embodiment, a flow path valve 52 'provided in an ink supply tube 51 can be driven by air. It is constituted by a valve.

FIG. 6 (a) shows an embodiment of a flow path valve 52 '. In this embodiment, four flow paths are provided in a single unit. The system operates similarly. The valve 154 has a shaft portion slidably supported by the casing 156 and is urged by a spring 153 to be pressed by the packing 155 in a normal state. A lid 151 having a role of fixing the spring 153 and connecting to the tube 51 is fixed to an upper portion of the casing 156. 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 valve 15 is provided at the lower opening of the casing 156.
The flexible film 157 is provided so as to form a clearance (indicated by c in FIG. 6B) with respect to the operating shaft 4. The flexible film 157 may be made of rubber or the like, but in this embodiment, the flexible film is a laminate obtained by bonding a polyethylene film, which is a thermoplastic resin, to a film obtained by depositing aluminum on a PET film. Film is used. According to this embodiment, the flexible film 157 can be joined to the casing 157 by heat welding.
Further, it is more effective in preventing the permeation of moisture or the invasion of air.

Since the ink flows upward due to the pressure as shown by the arrow a in FIG.
This is preferable because no gas remains in the interior of the device. A cover 159 is provided below the plastic film 157 via a diaphragm 158 made of a rubber material and integrally formed with a pressure receiving portion 161 to form a chamber 160. The cover 159 is formed integrally with an air port to the chamber 160 and is connected to the branch plate 66 via a bypass pipe 65 as shown in FIG.

In this embodiment, when the air pump 61 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 membrane 157. FIG. 6 (b)
As shown in (2), the ink flow path is shut off.

When the air pump 61 is operated, the inside of the chamber 160 is pressurized, and the diaphragm 158 is uniformly loaded by the pressure. This uniform load becomes an urging force according to the area of the pressure receiving portion 161 and the diaphragm 158 is displaced.
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,
The flow path is opened as shown in FIG.

Therefore, the flow path is opened only by operating the air pump 61 at the start of the recording operation, and the ink circulation is performed. When the recording operation is completed, the ink supply flow path 51 connecting the recording head 1 and the ink cartridge 41 can be closed by stopping the air pump 61, and the ink is stored in the sub tank 32. For a long period of time.

[0029]

According to the present invention, it is possible to prevent the can for a long time remain filled with specified amount of ink in sub Butanku, sub-tank of the ink by long-term standing solidified .

[Brief description of the drawings]

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

FIG. 2 is a diagram showing an embodiment of the ink jet recording apparatus of the present invention.

FIG. 3 is an assembled perspective view showing one embodiment of a sub tank of the recording apparatus.

FIG. 4 is a sectional view showing an embodiment of an ink cartridge of the recording apparatus.

FIG. 5 is a flow path configuration diagram showing a second embodiment of the present invention.

FIGS. 6A to 6C are an assembly perspective view and a sectional view, respectively, showing an embodiment of a valve means of the recording apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 2 Carriage 3 Pressure chamber 4,5 Common ink chamber 6,7 Ink supply port 10 Platen 30 Subtank unit 32 Subtank 41 Ink cartridge 51 Supply tube 52 Flow path valve (valve means) 61 Air pump (ink supply means)

Claims (4)

(57) [Claims] 1. Two commons communicating with both sides of a pressure generating chamber
Ink chambers and the common ink chambers
An ink- jet recording head that has an ink supply port through which ink flows in , discharges ink droplets in response to a print signal, a sub-tank made of a flexible film, and ink in the sub-tank
Sub tank with ink full detector to detect full
Unit, the ink jet recording head and the sub tank unit.
A carriage on which the cartridge is mounted , and outside the carriage and below the sub tank.
An ink cartridge comprising an ink bag disposed therein, and an ink cartridge from the ink cartridge to a sub-tank unit.
And an ink supply means for supplying ink to the ink jet recording head.
The supply port is connected to the sub tank unit and the other ink supply
A supply port is connected to the ink cartridge via valve means.
And the ink supply means
To the sub-tank unit
Refill ink, and after refilling the ink,
Stop the step and let the ink in the sub tank unit
Ink cartridge via the ink jet recording head
In the ink jet recording apparatus for flowing backward to the ridge, at the time when the recording operation is completed , the ink full detector
Until the ink full state is detected,
When more ink is supplied to the sub-tank unit, Inkufuru condition is detected by the Inkufuru detector
To stop the ink supply and close the valve means.
Let the ink jet recording apparatus. 2. An ink jet recording apparatus according to claim 1, wherein said valve means is constituted by a normally closed solenoid valve. 3. The ink cartridge according to claim 2, wherein
Acting on the ink bag by storing the bag and the ink bag
And an airtight container for
Supply means for supplying compressed air to the airtight container;
Pump, and connect the air pump and the airtight container.
An ink jet recording apparatus according to claim 1 which is constituted by a valve provided in the flow path. 4. The air pump according to claim 1 , wherein
4. A valve which is opened by compressed air.
3. The ink jet recording apparatus according to claim 1.