JP2001277544A - Ink supply device and ink jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eject ink drops while holding stable jet characteristics by temporarily storing air bubbles getting mixed in ink from the ink supply route from an ink tank to a recording head, each joint part and the nozzles of the recording head to directly discharge them from the nozzles of the recording head. SOLUTION: An ink holding part 9 and an air bubble holding part 10, which is provided so as to communicate with the upper part of the ink holding part 9, are provided in the ink buffer part 8, which is mounted on a carriage 2 and connected to the ink supply route 12 on the primary side thereof and connected to the recording head 6 on the secondary side thereof, and air bubbles getting mixed in ink from the ink supply route 12 or the joint part of the ink supply route 12 are stored in the air bubble holding part 10 of the ink buffer part 8 while the pressure fluctuations of ink generated by the scanning of the carriage 2 are suppressed to be prevented from being sent to the recording head 6 to stably discharge ink from the nozzles of the recording head 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink supply apparatus and an ink jet recording apparatus for supplying ink from a sub-tank to a head unit mounted on a carriage and ejecting ink from a recording head of the head unit. The present invention relates to stabilizing the ejection characteristics of ink droplets by suppressing the ejection.

[0002]

2. Description of the Related Art In recent years, an ink supply mechanism of a recording apparatus such as an ink jet ejection type printer, a facsimile, a copying machine, etc. has a head in which ink stored in a main tank is mounted on a carriage via a flexible ink supply tube. In many cases, ink is supplied to a unit and ejected as droplets from a recording head of a head unit for printing.
Thus, the ink supply mechanism that supplies the ink in the main tank to the head unit via the ink supply tube is:
Bubbles enter and permeate from the ink supply tube joints and ink supply tubes, etc., and bubbles enter the ink inside the ink tanks and ink supply tubes even when they are detached to replace the ink tank cartridge. there is a possibility. In addition, bubbles may flow backward from the nozzles of the recording head during printing or scanning of the carriage, causing the bubbles to enter the ink supply path. If the air bubbles mixed into the ink supply path reach the recording head during printing, the flow of the ink becomes worse or cut off, thereby causing a printing failure.

In order to prevent air bubbles mixed in the ink supply path from reaching the recording head during printing, for example, as shown in JP-A-10-114081, a sub-tank is provided with an air vent valve, and the air bubbles are provided in the sub-tank. When the pressure in the space of the sub-tank rises, air is discharged from the air release valve to the atmosphere.
As shown in Japanese Patent Publication No. 5 (1993), a deaerator is provided in the ink supply path,
An ink circulation path for returning the ink passing through the deaerator to the ink tank, and when a predetermined amount of dissolved gas is contained in the ink in the ink supply path, the ink is returned from the ink supply path to the ink tank, and To prevent the ink contained in the bubbles from being supplied.

[0004]

However, even if the air accumulated in the sub-tank is exhausted or the ink is degassed in the ink supply path, the air is mixed into the ink near the recording head from the joint between the sub-tank and the recording head. In addition, air bubbles mixed in from the nozzles of the print head cannot be removed, and these air bubbles block a system for supplying ink to the print head during printing, resulting in insufficient ink supply and printing defects.

The present invention has been made to solve the above-mentioned disadvantages, and temporarily collects air bubbles introduced from the ink supply path from the ink tank to the recording head and from each joint portion and the nozzles of the recording head and directly discharges the bubbles from the nozzles of the recording head. Let me
It is an object of the present invention to provide an ink supply device and an ink jet recording device capable of ejecting ink droplets with stable ejection characteristics.

[0006]

An ink supply device according to the present invention supplies ink stored in a main tank to a recording head mounted on a carriage reciprocating along a print sheet via an ink supply path. In the supply device, an ink buffer provided on a carriage, a primary side connected to an ink supply path, and a secondary side connected to a recording head, an ink holding unit, and a bubble provided in communication with an upper part of the ink holding unit. A holding section, and an ink supply path connected to an ink supply port at an upper end of the ink holding section and connected to an ink supply path connected to a recording head, and a bubble discharge path connected to an air discharge port at an upper end of the bubble holding section. The air stored in the bubble holding unit is suctioned from the recording head and discharged.

The connection path of the ink supply path connected to the ink supply port of the ink holding section is provided so as to be inclined so that the ink supply port side is higher, and the connection path of the bubble supply path connected to the air discharge port of the bubble holding section is provided. It is desirable that the connection path is also provided so as to be inclined so that the air discharge port side is higher.

In addition, the bubble discharge path of the bubble discharge path is so controlled that the fluid resistance of the bubble discharge path communicating with the ink supply path is smaller than the fluid resistance of the connection path from the ink supply port of the ink supply path to the communicating portion of the bubble discharge path. It is preferable to determine the cross-sectional area and the cross-sectional area of the connection path of the ink supply path.

Further, it is preferable to arrange the ink supply path and the ink inflow path so that the ink supply path of the ink holding section is at an acute angle with the ink inflow path through which the ink flows into the ink holding section.

[0010] An ink jet recording apparatus according to the present invention includes the above ink supply device.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink jet printer according to the present invention scans a carriage along a carriage guide rod while supplying ink stored in a main tank to a head unit mounted on the carriage via an ink supply tube. Printing is performed by ejecting ink as droplets from the recording head of the unit. The carriage has an ink buffer unit having a primary side connected to an ink supply tube and a secondary side connected to a recording head.

The ink buffer unit suppresses pressure fluctuations caused by scanning by the carriage, and has an ink holding unit and a bubble holding unit provided in communication with an upper portion of the ink holding unit. The ink introduction path connected to the lower part of the ink holding unit is connected to the ink supply tube, and the ink supply path connected to the upper end of the ink holding unit is connected to the recording head. The bubble discharge path connected to the upper end of the bubble holding unit communicates with the ink supply path. The wall of the ink supply path side of the ink holding unit is formed vertically,
An inclined portion is provided on the opposite wall, and the width decreases toward the bubble holding portion side. Further, a head maintenance / recovery device is provided at a predetermined position near the home position of the carriage that scans the recording head. The head maintenance / recovery device has a head cap that can be in close contact with the recording head, a suction pump, an ink discharge tube, and a discharge tank.

In this ink jet printer, when the cartridge constituting the main tank is replaced or the power is turned on, the recording head is moved to the position of the head maintenance / recovery device, the head cap is brought into close contact with the recording head, and the suction pump is driven. Then, the ink is sucked from the nozzles of the recording head to partially discharge the ink in the ink buffer unit. When partially discharging the ink in the ink buffer unit, the air in the bubble holding unit is discharged together with the ink in the ink holding unit,
The inside of the bubble holding unit is filled with ink. In this state, when printing is performed by scanning the carriage and ejecting ink from the recording head, air bubbles or ink supply tubes that have entered the ink in the ink supply path from each joint between the ink tank and the ink buffer. The air bubbles that have passed through and mixed with the ink flow are guided to the ink holding unit of the ink buffer unit along with the flow of ink generated by printing. The bubbles guided to the ink holding unit move upward inside the ink holding unit, and the bubbles that have moved upward are guided to the bubble holding unit along the inclined portion of the ink holding unit, and are stored at the upper portion of the bubble holding unit. . On the other hand, ink required for printing is supplied to the recording head through an ink supply path connected to the upper end of the ink holding unit. When the ink is supplied to the recording head, the ink flows out from the ink supply port of the ink holding section provided below the air discharge port provided at the top of the bubble holding section to the ink supply path. Is supplied as a bubble to the recording head.

When ink is supplied to the recording head and printing is repeated in this manner, the amount of air stored in the bubble holding unit is changed from the ink supply port of the ink holding unit to a position at a certain height at regular time intervals or in the bubble holding unit. At each timing until the air is filled, the recording head is moved to the position of the head maintenance / recovery device, the head cap is brought into close contact with the recording head, the suction pump is driven, and the ink is sucked from the nozzles of the recording head and the ink buffer unit is moved. Is partially discharged, and the air in the bubble holding unit is discharged to fill the bubble holding unit with the ink. By repeating the printing operation by ejecting ink from the recording head and the suction operation by the head maintenance / recovery device,
This prevents bubbles mixed in from the respective joints and the ink supply tube between the ink tank and the ink buffer from being sent to the recording head, and stably ejects ink from the nozzles of the recording head.

[0015]

FIG. 1 is a block diagram of one embodiment of the present invention.
The ink jet printer shown in FIG. 1 supplies the ink stored in the main tank 1 to a head unit 5 mounted on the carriage 2 via a fixed ink supply tube 3 and a flexible ink supply tube 4 while moving the carriage 2. The ink is ejected as droplets from the recording head 6 of the head unit 5 by scanning following the carriage guide rod 7 and printing is performed. The carriage 2 has a primary side connected to an ink supply tube 4 as shown in the configuration diagram of FIG.
The next side has an ink buffer unit 8 connected to the recording head 6.

As described above, the ink supply mechanism that supplies the ink in the main tank 1 to the head unit 5 via the ink supply tube 4 is provided with a recording head that changes in ink pressure inside the ink supply tube 4 due to the scanning of the carriage 2. 6 has an adverse effect on the ejection characteristics of the droplet ejected from 6. The pressure fluctuation generated by the scanning of the carriage 2 is generated in the ink inside the ink supply tube 6 when the carriage 2 reciprocates following the carriage guide rod 7. Moves from the position A to the position B following the carriage guide rod 7, the ink supply tube 4 also moves with the movement of the carriage 2. When the ink supply tube 4 moves, a relative speed difference occurs between the ink supply tube 4 and the ink inside the ink supply tube 4. Due to this speed difference, the ink inside the ink supply tube 4 stops after a certain time from stopping the carriage 2. Therefore, when the reciprocating operation of the carriage 2 is repeated, the ink inside the ink supply tube 4 is vibrated, and the pressure supplied to the ink supplied to the head unit 5 has a fluctuation in pressure. When the pressure fluctuation amount of the ink becomes large, the meniscus of the ink generated in the nozzle of the recording head 6 is broken, and bubbles are drawn from the nozzle,
Unintended injection occurs. Further, even if it does not reach that, it will affect the amount and speed of the droplet ejected at the time of printing.

The ink buffer unit 8 suppresses pressure fluctuations caused by the scanning of the carriage 2. As shown in the configuration diagram of FIG. 2, the ink buffer unit 8 includes an ink holding unit 9 and a bubble holding unit 10 provided in communication with an upper portion of the ink holding unit 9. An ink introduction path 11 connected to a lower portion of the ink holding section 9 is connected to the ink supply tube 4, and an ink supply path 12 connected to an upper end of the ink holding section 9 is connected to the recording head 6. The bubble discharge path 13 connected to the bubble holding unit 10 communicates with the ink supply path 12. Connection path 12a of ink supply path 12 connected to ink supply port 14 of ink holding section 9
The connection path 13a of the bubble discharge path 13 connected to the air discharge port 15 of the bubble holding unit 10 is also inclined such that the air discharge port 15 side is high. Is provided.

As shown in the side sectional view of FIG. 3, at least one side of the ink holding portion 9 and the bubble holding portion 10 which is in contact with the ink is formed of a film 16 having flexibility. The pressure fluctuation generated in the ink supply tube 4 is absorbed and attenuated by the film 16 having the capacity and flexibility of the ink holding unit 9 by the same operation as the capacitor of the electric circuit. By providing the ink buffer section 8, the ink internal pressure fluctuation characteristic diagram A near the recording head in FIG.
As shown in (1), the pressure fluctuation of the ink supplied to the recording head 6 can be attenuated. In FIG. 4, B indicates the fluctuation of the ink internal pressure near the recording head 6 when the ink buffer unit 8 is not used.

The wall of the ink holding section 9 on the ink supply path 12 side is formed vertically, and an inclined section is provided on the opposite wall.
The width becomes narrower toward the bubble holding unit 10 side. Further, a head maintenance / recovery device 17 is provided at a predetermined position at the home position of the carriage 2 that scans the recording head 6. The head maintenance / recovery device 17 has a head cap 18 that can be in close contact with the recording head 6, a suction pump 19, an ink discharge tube 20, and a discharge tank 21. When the recording head 6 reaches the position of the head maintenance / recovery device 17,
The suction pump 19 is driven by bringing the head cap 18 into close contact with the recording head 6 to suck ink from the nozzles of the recording head 6 and discharge the ink from the ink discharge tube 20 to the discharge tank 21.

In the ink jet printer constructed as described above, when the cartridge constituting the main tank 1 is replaced or when the power is turned on, the recording head 6 is moved to the position of the head maintenance / recovery device 17, and the head cap 18 is moved to the recording head. 6, the suction pump 19 is driven to suck the ink from the nozzles of the recording head 6 and partially discharge the ink in the ink buffer unit 8. When the ink in the ink buffer unit 8 is partially discharged, the air in the bubble holding unit 10 is discharged together with the ink in the ink holding unit 9, and the inside of the bubble holding unit 10 is filled with the ink. In this state, when the carriage 2 is scanned to eject ink from the recording head 6 to perform printing, the ink buffer 1
The air bubbles that have entered the ink in the ink supply path from each joint and the air bubbles that have penetrated through the ink supply tube 4 from the respective joints ride on the flow of ink generated by printing, and are stored in the ink holding unit 9 of the ink buffer unit 8. Led to. The air bubbles guided to the ink holding unit 9 move upward inside the ink holding unit 9, and the air bubbles that have moved upward move toward the ink holding unit 9.
Is guided to the bubble holding portion 10 along the inclined portion of the airbag, and is stored in the upper portion of the bubble holding portion 10. On the other hand, the ink necessary for printing is supplied to the ink supply path 1 connected to the upper end of the ink holding unit 9.
2 to the recording head 6. When supplying ink to the recording head 6, the ink holding unit 9 provided below the air outlet 15 provided above the bubble holding unit 10.
Since the ink flows out from the ink supply port 14 to the ink supply path 12, it is possible to prevent the air in the bubble holding unit 10 from being mixed as bubbles and being supplied to the recording head 6.

When the ink is supplied to the recording head 6 and printing is repeated in this manner, the air amount stored in the bubble holding unit 10 is limited to a predetermined limit amount, that is, the ink amount in the ink holding unit 9 at regular time intervals. The recording head 6 is moved to the position of the head maintenance / recovery device 17 at each timing until the air is filled from the supply port 14 to a position at a certain height, and the suction cap 19 is brought into close contact with the head cap 18 by bringing the head cap 18 into close contact with the recording head 6. The ink is sucked from the nozzles of the recording head 6 to partially discharge the ink in the ink buffer unit 8, and the air in the bubble holding unit 10 is discharged to drive the bubble holding unit 10.
Fill the inside with ink. By repeating the printing operation by ejecting the ink from the recording head 6 and the suction operation by the head maintenance / recovery device 17, the ink is mixed from each joint between the ink tank 1 and the ink buffer unit 8, the ink supply tube 4, and the like. It is possible to prevent the generated air bubbles from being sent to the recording head 6, and to stably eject ink from the nozzles of the recording head 6.

The ink supply port 14 of the ink holding section 9
The air outlet 15 of the bubble holding unit 10 is provided above,
The connection path 12a of the ink supply path 12 is the ink supply port 1
The connection path 13 of the bubble discharge path 13 that is inclined so that the side 4 is higher and is connected to the air discharge port 15 of the bubble holding unit 10
a is also inclined so that the air outlet 15 side becomes higher, so that even if air bubbles are mixed in from the joint between the recording head 6 and the ink buffer unit 8 or air bubbles are mixed in from the recording head 6, the mixed air bubbles Under the influence of the relative weight difference with the ink, the ink is climbed upward, and is guided to the bubble holding unit 10 through the ink supply path 12 and the connection path 12 a or the ink supply path 12 and the bubble discharge path 13. Therefore, it is possible to prevent air bubbles mixed in from the joint between the recording head 6 and the ink buffer unit 8 or from the recording head 6 from adversely affecting the ink ejection characteristics of the recording head 6.

Further, in the above embodiment, the cross-sectional area of the bubble discharge path 13 is set so that the fluid resistance of the bubble discharge path 13 communicating with the ink supply path 12 is smaller than the fluid resistance of the connection path 12a of the ink supply path 12. When the cross-sectional area of the connection path 12a of the ink supply path 12 and the ink supply path 12 is determined, the recording head 6 is moved to the position of the head maintenance / recovery device 17, and the air in the bubble holding section 10 is sucked and removed together with a part of the ink. In this case, the amount of air suction can be increased and the amount of ink suction can be reduced, so that unnecessary suction of ink can be avoided. The head holding / recovering device 17 uses the bubble holding unit 1.
The suction pressure for sucking the air inside 0 is optimally set in accordance with the fluid resistance of the bubble discharge path 13 and the fluid resistance of the connection path 12a of the ink supply path 12, so that the suction pump 19
Ability can be reduced.

Further, the ink in the ink holding unit 9 is fan-shaped around the outlet of the ink introduction path 11 connected to the lower part of the ink holding unit 9 due to the pressure fluctuation generated in the ink supply tube 4 during the scanning of the carriage 2. The pressure wave spreads.
On the other hand, the connection path 12a of the ink supply path 12 connected to the ink supply port 14 of the ink holding section 9 is
Because the connection path 12a is provided at an acute angle with respect to the direction in which the pressure wave spreads, the pressure wave is applied to the ink in the ink supply path 12, that is, the ink communicating with the recording head 6. The ink and the air in the bubble holding unit 10 act as a damper against the pressure wave, and the influence of the pressure fluctuation generated in the ink supply tube 4 on the ink ejected from the recording head 6 is further suppressed. be able to.

[0025]

According to the present invention, as described above, the primary side is mounted on the carriage, and the primary side is connected to the ink supply path.
The ink buffer unit connected to the recording head on the next side is provided with an ink holding unit and a bubble holding unit provided in communication with an upper portion of the ink holding unit, while suppressing ink pressure fluctuation caused by scanning of the carriage. Bubbles mixed from the ink supply path and the joint section of the ink supply path are collected in the bubble holding section of the ink buffer section, preventing the bubbles from being sent to the print head, and stably ejecting ink from the nozzles of the print head. Can be.

Further, since the air accumulated in the bubble holding section is suctioned and discharged from the recording head at predetermined timings, the air accumulated in the bubble holding section can be reliably discharged. Bubbles can be prevented from being mixed into the ink supplied to the printer.

Further, the connection path of the ink supply path connected to the ink supply port of the ink holding section is provided so as to be inclined so that the ink supply port side is higher, and the bubble discharge path connected to the air discharge port of the bubble holding section. The connection path is also inclined so that the air discharge port side is high, so that even if air bubbles enter from the joint between the print head and the ink buffer section, or if air bubbles enter from the print head, The ink can be guided to the holding unit, and bubbles mixed in from the joint between the print head and the ink buffer or the print head can be prevented from adversely affecting the ink ejection characteristics of the print head.

Further, the bubble discharge path of the bubble discharge path is so controlled that the fluid resistance of the bubble discharge path communicating with the ink supply path is smaller than the fluid resistance of the connection path from the ink supply port of the ink supply path to the communicating portion of the bubble discharge path. By determining the cross-sectional area and the cross-sectional area of the connection path of the ink supply path, when suctioning and removing air in the bubble holding section together with part of the ink, the air suction amount is increased and the ink suction amount is reduced. And the ink need not be wasted.

Further, by arranging the ink supply path and the ink inflow path so that the ink supply path of the ink holding section is at an acute angle with the ink inflow path for flowing the ink into the ink holding section, the ink supply tube is scanned by the carriage. It is possible to further suppress the influence of the pressure fluctuation generated in the ink on the ink ejected from the recording head.

Further, by using this ink supply device in an ink jet ejection type printer, facsimile, or copier, it is possible to eject ink droplets with stable ink ejection characteristics to form a high quality image.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of an ink buffer unit.

FIG. 3 is a side sectional view of an ink buffer unit.

FIG. 4 is a graph showing ink internal pressure fluctuation characteristics near a print head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Main tank, 2; Carriage, 3; Fixed side ink supply tube, 4; Ink supply tube, 5; Head unit, 6; Recording head, 7; Carriage guide rod, 8; Ink buffer section, 9; , 10;
Bubble holding section, 11; ink introduction path, 12; ink supply path, 13; bubble discharge path, 14; ink supply port, 1
5; air outlet, 16; film, 17; head maintenance and recovery device, 18; head cap, 19; suction pump, 2
0: ink discharge tube, 21: discharge tank.

Claims (5)

[Claims] 1. An ink supply device for supplying ink stored in a main tank to a recording head mounted on a carriage reciprocating along a print sheet via an ink supply path, wherein an ink supply device mounted on the carriage supplies ink on a primary side. An ink buffer unit connected to the print head and having a secondary side connected to the recording head, the ink buffer unit having an ink holding unit and a bubble holding unit provided in communication with an upper portion of the ink holding unit; The ink supply path connected to the ink supply port and connected to the recording head communicates with the bubble discharge path connected to the air discharge port at the upper end of the bubble holding section, and the air collected in the bubble holding section is sucked from the print head. And an ink supply device for discharging. 2. A connection path of an ink supply path connected to an ink supply port of the ink holding section is provided so as to be inclined so that the ink supply port side is higher, and a bubble connected to an air discharge port of the bubble holding section. 2. The ink supply device according to claim 1, wherein a connection path of the discharge path is also inclined so that the air discharge port side is higher. 3. The bubble discharge path so that the fluid resistance of the bubble discharge path communicating with the ink supply path is smaller than the fluid resistance of the connection path from the ink supply port of the ink supply path to the communication portion of the bubble discharge path. The ink supply device according to claim 1, wherein a cross-sectional area of the ink supply path and a cross-sectional area of the ink supply path are determined. 4. The ink supply path according to claim 1, wherein the ink supply path and the ink inflow path are arranged so that the ink supply path of the ink holding section is at an acute angle with the ink inflow path through which the ink flows into the ink holding section. Ink supply device. 5. An ink jet recording apparatus comprising the ink supply device according to claim 1.