JP2003001846A - Ink supply device and ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably supply ink to a recording head for high-speed printing for a long time. SOLUTION: When the ink is supplied to a sub-tank 2 from a main tank 11, an atmospheric opening valve 22 makes the inside of the sub-tank 2 opened to the atmosphere, and a negative pressure generating part 26 is expanded to supply the ink to the sub-tank 2 from an ink supply part 21. After the sub- tank 2 is refilled with the ink, the valve 22 is blocked to contract the generating part 26, generate negative pressure in the sub-tank 2 and prevent a bad influence from being exerted on the ink which is supplied to the recording head 3 in order to be used for the printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink supply device and an ink jet recording device for supplying ink to a recording head of an ink jet recording device.

[0002]

2. Description of the Related Art On-demand type ink jet recording systems used in printers, facsimiles, copiers, etc.
A vibrating plate is provided on a part of the wall of the ink liquid chamber that has a nozzle and is filled with ink, and the vibrating plate is displaced by a piezoelectric actuator or the like to change the volume in the ink liquid chamber and increase the pressure to eject ink from the nozzle. A method is used in which a heating element that generates heat when energized is provided in the ink liquid chamber, and ink is ejected from the nozzle by increasing the pressure in the liquid chamber by the bubbles generated by the heat generation of the heating element. Printers using this ink jet recording system are widely used for various purposes due to the recent price reduction, high image quality, and popularization of personal computers in general households.

One of the problems in using this ink jet printer is speeding up. To this speeding up, the driving frequency of active elements for ink ejection, the number of nozzles and the number of heads are increased. Has been done. Due to such high-speed printing, the ink in the ink cartridge for supplying the ink to the recording head is rapidly consumed, and therefore the number of times of replacement is large for a small capacity cartridge, which is not preferable in use. Further, when a large-capacity ink cartridge is mounted on the carriage, a drive system for scanning the carriage becomes large, which causes a problem that the printer becomes large. Therefore, as shown in, for example, Japanese Unexamined Patent Publication No. 10-128992, Japanese Unexamined Patent Publication No. 10-235892, and Japanese Patent No. 3053017, a small-capacity sub tank is mounted on a carriage, and a large-capacity main tank is installed in a printer. Installed on the main body,
When the amount of ink in the sub-tank is low due to printing, the sub-tank is replenished with ink from a large-capacity main tank.

[0004]

SUMMARY OF THE INVENTION
In the method disclosed in Japanese Patent Laid-Open No. 10-128992 or Japanese Patent Laid-Open No. 10-235892, the air permeability and moisture permeability of the tube and the attachment / detachment of the main tank mix the ink into the ink supply path that supplies ink from the main tank to the sub tank. Since a large amount of air enters the sub tank for a long period of time, the air enters the recording head from the sub tank, which deteriorates the printing performance. In order to avoid this deterioration of printing performance, use it only for disposable recording heads with a short life, or use an ink supply tube that connects the sub tank and the main tank with excellent air permeability and moisture permeability. Inconveniences such as the need to use a different one will occur. Further, in the method shown in Japanese Patent No. 3053017, the ink supply tube and the air suction tube are connected to the sub tank, and ink is filled while bleeding air from the sub tank. There is no problem of air accumulation, but it is necessary to connect the ink supply tube and the air suction tube to the sub tank. Since the sub-tank is mounted on the carriage together with the recording head for scanning, the tube connected to the sub-tank needs to have a length corresponding to the scanning amount, and it is a disadvantage that many long tubes must be crawled inside the printer. There is.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink supply device and an ink jet recording device, which are capable of remedying the above disadvantages and stably supplying ink to a recording head for high speed printing over a long period of time. is there.

[0006]

SUMMARY OF THE INVENTION An ink supply device of the present invention includes a sub tank for supplying ink to a recording head for ejecting ink from a nozzle to form an image, the sub tank being provided independently of the sub tank. In the ink supply device having a main tank for supplying a negative pressure, a negative pressure generating portion that expands and contracts by supplying and discharging a fluid is provided inside the sub tank, and a negative pressure is generated in the sub tank.

Further, the sub-tank is provided with an atmosphere opening part for opening the inside of the sub-tank to the atmosphere, a negative pressure generating part provided inside the sub-tank for expanding and contracting by supplying and discharging a fluid, and ink from the main tank. When supplying ink from the main tank to the sub tank, the inside of the sub tank is opened to the atmosphere by the atmosphere opening part and the negative pressure generating part is expanded to supply the ink from the ink supplying part to the sub tank. After replenishing the ink in the sub tank, the atmosphere opening portion is shut off and the negative pressure generating portion is contracted to surely generate the negative pressure in the sub tank.

Further, it is possible to prevent the negative pressure generating portion from expanding and contracting by supplying and discharging the ink to generate negative pressure and adversely affecting the supplied ink.

Further, by switching the ink supplied to the negative pressure generating section and the ink supply section by the ink flow path switching member, the negative pressure is generated in the sub tank with a simple structure.

Further, the sub-tank is provided with a negative pressure adjusting section for adjusting the internal negative pressure by passing only the air without passing the ink, and the negative pressure in the sub-tank containing the ink is kept constant. By forming the negative pressure adjusting portion with a porous body, clogging is prevented and the function is stably exhibited for a long period of time.

Further, the sub-tank is provided with a member for preventing the negative pressure generating portion from collapsing to prevent air bubbles from staying in the ink due to the air from the negative pressure adjusting portion.

Further, a filter for filtering outside air is provided in the atmosphere opening portion to prevent dust and the like contained in the atmosphere from entering the sub tank when the atmosphere opening portion opens the sub tank to the atmosphere.

Further, the sub-tank of the ink supply device is mounted on the carriage together with the recording head for ejecting ink from the nozzles to form an image, and the main tank is installed on the main body to mount a small sub-tank on the carriage. The carriage can be scanned at high speed, and the printing speed can be increased. In addition, the main body is equipped with a large-capacity main tank to reduce the frequency of replacement of the main tank.

[0014]

1 is a block diagram of an ink jet printer of the present invention. As shown in the figure, the ink jet printer 1 has four sub-tanks 2 respectively containing inks of cyan C, magenta M, yellow Y, and black Bk, and a plurality of nozzles, and ink is supplied from each sub-tank 2. Four recording heads 3, a carriage 4 on which the sub-tank 2 and the recording head 3 are mounted, paper feed trays 5a and 5b containing recording paper, and paper feed trays 5a and 5
It has a conveyance roller 8 that conveys the recording paper to the printing unit 7 from b or the manual feed table 6, and a discharge roller 10 that discharges the printed recording paper to the discharge tray 9. The sub-tank 2 is connected to a main tank 11 installed in the main body of the inkjet printer 1 via an ink supply tube 12, as shown in the configuration diagram of the ink supply device in FIG. When the image data sent from the host device is printed on the recording paper 13, the carriage 4 is moved to the carriage guide roller 14
The recording paper 1 conveyed in the direction of arrow B by the conveyance roller 8 and sent to the printing unit 7 while scanning in the direction of arrow A following
Ink is ejected from the nozzles of the recording head 3 according to the image data, and characters and images are recorded. When the ink is consumed by this printing, the ink is appropriately supplied from the main tank 11 to the sub tank 2 as needed.

As shown in the sectional view of FIG. 3, the sub tank 2 is fixed with a recording head 3 including a nozzle, an ink liquid chamber, an ejection pressure generating element and the like. In this sub tank 2,
The ink supply unit 21, the atmosphere release valve 22, the ink remaining amount detection sensor 23 that detects that the ink remaining amount in the sub tank is low, and the replenishment that detects completion of ink replenishment when replenishing ink from the main tank 11. Completion sensor 24
And a negative pressure adjusting unit 25 and a negative pressure generating unit 26. The ink supply unit 21 includes a first ink supply pipe 27 that penetrates the side wall of the sub tank, an ink supply tube 12 connected to the main tank 11, and a first ink supply pipe 27.
And a pump 28 provided at the connecting portion with. The atmosphere release valve 22 has an opening 29 provided on the upper surface of the sub tank 2.
And a seal portion 30 that seals the opening 29, and a seal portion 3
A spring mechanism 31 for pressing 0 to the opening 29, and a seal portion 3
It has a pressing mechanism section 32 for pushing 0 into the sub tank 2 and a filter 33 provided outside the opening 29, and normally shuts off the inside of the sub tank 2 from the atmosphere.
2 to open the inside of the sub tank 2 to the atmosphere. The ink remaining amount detection sensor 23 and the replenishment completion sensor 24 detect the ink end or the ink replenishment completion by using, for example, a change in the electric resistance in the sub tank 2 or an optical sensor, and estimate the ink remaining amount from the output image signal. Set the replenishment amount.
The negative pressure adjusting unit 25 is provided at the bottom of the sub tank 2 and adjusts the negative pressure in the sub tank 2. For example, the hole diameter and depth are set so that the ink inside does not flow out and bubbles are not sucked. It has micro holes and porous body set, and when the negative pressure in the sub tank 2 becomes large, it takes in air from the outside to adjust the negative pressure, or an elastic body is provided in a part of the sub tank 2 to deform the elastic body. The negative pressure in the sub tank 2 is adjusted by. The negative pressure generating section 26 includes a second ink supply pipe 34 provided through the side wall of the sub tank 2 and the main tank 1.
It has a pump 35 provided at a connecting portion between the ink supply tube 12 and the second ink supply tube 34 connected to 1, and a bag member 36 provided in the sub tank 2. Bag member 3
6 is made of a low-rigidity material such as a resin film or rubber, and has an opening at the inner wall of the sub tank 2 or the second ink supply pipe 34.
It is fixed to the tip of the.

The operation of supplying ink from the main tank 11 to the sub-tank 2 constructed as described above will be described with reference to the process chart of FIG. When the ink is ejected from the recording head 3 and the printing is repeated and the ink in the sub tank is consumed and the ink remaining amount sensor 23 detects the ink end, as shown in FIG. 4A, the air release valve 22 is pressed. The seal portion 30 is pushed into the sub tank 2 by the mechanism portion 32 to open the atmosphere release valve 22. This atmosphere release valve 22
When opening, the sub tank 2 is in a negative pressure state,
Air flows into the sub tank 2 at the moment when the atmosphere release valve 22 is opened. At that time, if the atmosphere contains a large amount of dust, there is a risk that dust may enter the sub tank 2 together with the air. The filter 33 prevents this dust from entering the sub tank 2.

In this state, the pump 35 of the negative pressure generator 26 is driven to drive the main tank 11 to the second ink supply pipe 34.
Ink is injected into the bag member 36 through. Bag member 36
When ink is injected into the bag, the bag member 36 expands, and a part of the air in the sub tank 2 is discharged through the atmosphere release valve 22, as shown in FIG. After the ink is injected into the bag member 35 to expand the bag member 36, the negative pressure generating unit 26
The driving of the pump 35 is stopped, and the pump 28 of the ink supply unit 21 is driven to supply the ink from the main tank 11 into the sub-rank 2 through the first ink supply pipe 27.
When this ink is supplied into the sub-tank 2, the air in the sub-tank 2 is discharged from the atmosphere opening valve 22 and it is possible to prevent the air from staying in the sub-tank 2. When the ink level in the sub tank 2 rises due to the ink supplied to the sub tank 2 and the upper surface of the ink reaches the replenishment completion sensor 24 as shown in FIG. 4C, the driving of the pump 28 is stopped and the sub tank 2 To stop the ink supply to. Next, as shown in FIG.
Is closed and the pump 35 of the negative pressure generating unit 26 is driven to suck the ink in the bag member 36 and discharge it to the outside. By discharging the ink in the bag member 36, the bag member 36 contracts and a negative pressure is generated in the sub tank 2. From this state,
Printing can be started again by the recording head 3.
When the printing by the recording head 3 is repeated and the ink in the sub tank 2 is consumed as shown in FIG.
The negative pressure in the sub tank 2 gradually increases. If this negative pressure becomes too large, bubbles may be sucked from the nozzles of the recording head 3 and normal printing may not be performed. If the negative pressure in the sub tank 2 becomes too large, the sub tank 2
This is prevented by the negative pressure adjusting unit 25 provided at the bottom of the.

As described above, in order to replenish the sub-tank 2 mounted on the carriage 4 with ink from the large-capacity main tank 11 installed in the main body as needed, a small sub-tank 2 may be mounted on the carriage 4. Can be scanned at high speed, and the printing speed can be increased.
Also, since the main body can be provided with a large-capacity main tank 11, the frequency of replacement of the main tank 11 can be reduced, and the ink-jet printer 1 with good usability can be realized. Furthermore, when the sub tank 2 is refilled with ink, the sub tank 2 is opened to the atmosphere,
The air that has flowed into the sub tank 2 together with the supplied ink can be discharged to the outside, and highly reliable printing can be performed for a long period of time. Further, the same driving mechanism as the pump 28 or the like of the ink supply unit 21 may be used as a drive mechanism such as a pump 35 or a valve that supplies ink to the bag member 36 of the negative pressure generating unit 26 to expand or contract the bag member 36. Therefore, common parts can be achieved. In addition, for example, the bag member 36
If the bag member 36 has a pinhole when it is inflated with air, the air in the subtank 2 will flow into the ink supplied to the subtank 2 from the pinhole of the bag member 36, causing a problem of bubbling the ink. In addition, when the bag member 36 is contracted, ink may enter the air pump, causing a malfunction of the pump. On the other hand, by injecting the ink into the bag member 36 to expand the bag member 36, even if the bag member 36 has, for example, a pinhole or the like, the above-mentioned inconvenience does not occur, and the selectivity of the material of the bag member 36 is expanded. In addition, the required quality can be lowered, and the strike can be reduced.

In the sub-tank 2 shown in FIG. 3, the case where the ink supply unit 21 and the negative pressure generation unit 26 are provided with the pumps 21 and 35, respectively, has been described, but one ink supply unit 21 and one negative pressure generation unit 26 are provided. Ink may be supplied by a pump. For example, as shown in the configuration diagram of FIG. 5, the negative pressure generating unit 26 has an ink flow path inside and has a tip end portion sealed, and an ink supply port 37 is provided on the side surface near the sealed tip end portion.
The ink supply channel 21 has an ink flow path switching member 38 and a side wall of the sub-tank 2 provided in an opening of the bag member 36, and a seal hole 39 for sliding the ink flow path switching member 38. A negative pressure generating portion is provided at a connection portion between the ink supply tube 12 connected to the main tank 11 and the ink flow path switching member 38, which has an ink supply passage 40 communicating with an intermediate portion of the seal hole 39 of the pressure generating portion 26. 26 and the ink supply unit 21
It has a pump 41 commonly used in.

When ink is ejected from the recording head 3 fixed to the sub-tank 2 constructed as described above and printing is repeated and ink in the sub-tank is consumed and the ink remaining amount sensor 23 detects the ink end, FIG. As shown in (a), the atmosphere release valve 22 is opened. Then, the ink flow path switching member 38 is moved to the bag member 36 side, the ink supply port 37 at the tip is inserted into the bag member 36, and the pump 41 is driven to pass the ink flow path switching member 38 from the main tank 11 to the bag. Ink is injected into the member 36 to expand the bag member 36. After the ink is injected into the bag member 36 to expand the bag member 36, the driving of the pump 41 is stopped. Thereafter, as shown in FIG. 6B, the ink flow path switching member 38
Back to position the ink supply port 37 at the front end in the communication part of the ink supply path 40, and drive the pump 41 to drive the ink from the main tank 11 into the sub-rank 2 through the ink flow path switching member 38 and the ink supply path 40. To supply. When this ink is supplied into the sub-tank 2, the air in the sub-tank 2 is discharged from the atmosphere opening valve 22 and it is possible to prevent the air from staying in the sub-tank 2. When the ink level in the sub tank 2 rises due to the ink supplied to the sub tank 2 and the upper surface of the ink reaches the replenishment completion sensor 24 as shown in FIG. 6C, the driving of the pump 41 is stopped and the sub tank 2 To stop the ink supply to. Next, as shown in FIG. 6D, the atmosphere opening valve 22 is closed and the ink flow path switching member 38 is moved to the bag member 36 side to insert the ink supply port 37 at the tip end into the bag member 36.
The pump 41 is driven to suck the ink in the bag member 36 and discharge it to the main tank 11. By discharging the ink in the bag member 36, the bag member 36 contracts and a negative pressure is generated in the sub tank 2. In this state, driving of the pump 41 is stopped, the ink flow path switching member 38 is retracted, and the ink supply port 37 is sealed by the seal hole 39, so that the printing can be started again by the recording head 3. As the printing by the recording head 3 is repeated and the ink in the sub tank 2 is consumed as shown in FIG. 6E, the negative pressure in the sub tank 2 gradually increases. If this negative pressure becomes too large, bubbles may be sucked from the nozzles of the recording head 3 and normal printing may not be performed. This sub tank 2
The negative pressure in the inside of the sub-tank 2 is adjusted to be too large by the negative pressure adjusting portion 25 provided at the bottom of the sub tank 2 and made of a porous body.
When air is taken in by the negative pressure adjusting unit 25, dust may be mixed with the air, but since the area can be increased by using a porous body, there is no problem of clogging due to dust and the function can be stably maintained. . Although the negative pressure is adjusted by using the negative pressure adjusting unit 25 in the above description, the negative pressure can be maintained by opening and closing the atmosphere opening valve 22 in a short cycle even in the configuration without these negative pressure adjusting members. It is possible.

The sub-tank 2 shown in FIG. 5 has been described in the case where the ink flow path switching member 38 is provided in the negative pressure generating section 26. However, the ink flow path switching member 38 is provided in the ink supply section 21.
It may be provided in.

Further, the sub-tank 2 has a bag member 36 incorporated therein, but the bag member 36 is in a contracted state during printing. Therefore, in order to obtain high flexibility, the bag member 36
If the material is formed of a thin material, a part of the bag member 36 may be collapsed and bent as shown in (b) of the sectional view of FIG. 7.
When the bag member 36 falls and bends, when air is mixed into the sub tank 2 from the negative pressure adjusting section 25 that adjusts the negative pressure,
Air bubbles 42 are trapped by the bent bag member 36. This bubble 42 is trapped and the sub tank 2
If it stays relatively close to the recording head 3 without ascending to the upper part, it is not preferable because bubbles may flow out into the recording head 3 during printing. Therefore, as shown in FIG. 7A, ribs 43 are formed on the side surface side of the bag member 36 to prevent the bag member 36 from collapsing or breaking, and to prevent the air bubbles 42 from staying.

Further, the case where the filter 33 is provided on the surface of the opening 29 of the atmosphere release valve 22 in order to prevent dust from entering the sub tank 2 when the atmosphere release valve 22 is opened has been described. As shown in the partial cross-sectional view of FIG. 8, a resin filter 33 having high flexibility and flexibility may be provided on the side of the seal portion 30 in the sub tank 2. Further, the seal portion 30 may be provided with a convex portion 44 as shown in the partial sectional view of FIG. 9, and the convex portion 44 may be pressed by the pressing mechanism portion 32 to open or close the atmosphere opening valve 22. .

When a metal pin is used as the pressing member 321 of the pressing mechanism section 32 for opening and closing the atmosphere opening valve 22, the ink remaining amount detecting sensor 23 at the bottom of the sub tank 2 is used, as shown in FIG. It is possible to detect the replenishment completion by detecting the difference in the electric resistance value between the replenishment completion sensor 24 and the electrode, and the pressing member 3 can be omitted.
Since the reference numeral 21 touches the ink only when the ink is replenished, deterioration due to electrolytic corrosion or the like can be reduced and the reliability of the sensor can be improved.

[0025]

EXAMPLES Example 1 The sub-tank 2 shown in FIG. 3 is formed of polyethylene resin so that the volume is about 5 cc.
The bag member 36 is made of polyethylene having a thickness of 0.05 mm, and is in a deflated state when there is no pressure, and about 0 when expanded.
A volume of 5 cc was used. Also, sub tank 2
The negative pressure adjusting portion 25 having a minute hole is provided at the bottom of the
In order to evaluate the sub-tank 2 instead of the recording head 3, a fluid resistance element set to a fluid resistance value equivalent to that of the recording head 3 was bonded to the opening on the bottom surface of the sub tank 2 to which the recording head 3 was bonded. In this way, an evaluation sample was produced and the ink replenishment status was evaluated. When the negative pressure in the sub tank 2 was measured by the pressure sensor in a state where the ink was supplied to the sub tank 2 and the bag member 36 was contracted, it was about −
It was 0.4 kPa. From this state, a pump is connected to the fluid resistance element, ink is sucked at a flow rate that actually flows by the recording head 3, and the negative pressure change and the ink level are observed, and the ink level drops as the ink is discharged. At the same time, the negative pressure in the sub-tank increased, and air started to be injected from the minute holes of the negative pressure adjusting section 25 at about -1 kPa, and ink was discharged while maintaining a substantially negative pressure. After the ink end was detected, the ink supply and discharge were repeated again. As a result, it was possible to obtain stable performances such as the ink replenishment state and the negative pressure value for a large number of repetitions.

[Embodiment 2] The sub-tank 2 shown in FIG. 5 is made of polyethylene resin so that the volume is about 5 cc, and the bag member 36 is made of polyethylene having a thickness of 0.05 mm. Then, a material having a volume of about 0.5 cc when expanded was used. Further, urethane foam is provided at the bottom of the sub-tank 2 as a negative pressure adjusting portion 25 having an area of about 10 mm ² , and the opening of the bottom of the sub-tank 2 where the recording head 3 is joined is replaced by the sub-tank 2 instead of the recording head 3. In order to evaluate, the fluid resistance element set to the fluid resistance value equivalent to that of the recording head 3 was joined.
The ink replenishment status was evaluated using this evaluation sample.
When negative pressure inside the sub tank 2 was measured with a pressure sensor in a state where the ink was supplied to the sub tank 2 and the bag member 36 was contracted, it was about -0.4 kPa. From this state,
When a pump is connected to the fluid resistance element and ink is sucked at a flow rate that actually flows from the recording head 3 to observe the change in negative pressure and the ink level, the ink level drops as the ink is discharged, and the sub-tank Negative pressure rises,
At about -0.8 kPa, air started to be injected through the urethane foam of the negative pressure adjusting section 25, and the ink was discharged while maintaining a substantially constant negative pressure. After the ink end was detected, the ink supply and discharge were repeated again. As a result, it was possible to obtain stable performance such as the replenishment state and the negative pressure value for many repetitions.

Example 3 A similar experiment was conducted by setting the volume capacity of the sub-tank 2 shown in FIG. 5 to 10 cc and the volume of the bag member 36 when inflated to be about 0.5 cc. As a result, the phenomenon in which the bag member 36 collapses as shown in FIG. 7A and the air from the negative pressure adjusting unit 25 is trapped during the ink discharge while the ink supply and discharge are repeated a plurality of times. I was observed. When the sub tank 2 with the air trapped therein is mounted on a shaker that reciprocates similarly to the main scanning of the carriage 4 and ink is discharged while vibrating, air bubbles are mixed in the ink. It was observed that the air was trapped in the ink in the sub tank 2, and a defect was confirmed. Therefore, FIG.
As shown in (b), ribs 43 are provided on the side surface of the sub-tank 2 to prevent the bag member 36 from collapsing.

[Fourth Embodiment] As a result of repeatedly supplying and discharging ink in a dusty environment without providing a filter 33 at the opening 29 of the atmosphere release valve 22 of the same subtank 2 as in the first embodiment, a negative result is obtained. Since air is not sucked from the pressure adjusting unit 25, the negative pressure value in the sub tank 2 becomes large, and the ink cannot be discharged. Then, when the minute hole portion of the negative pressure adjusting portion 25 of the sub tank 2 was observed, it was found that the dust was clogged and the fluid resistance value was large. Therefore, when the negative pressure adjusting section 25 was changed to a urethane foam having a large area as in the case of Example 2, the problem that the negative pressure was increased by repeating many experiments was solved. However, analysis of the ejected ink revealed that the ink contained dust. This dust is mixed in the opening 2 of the atmosphere release valve 22.
Assuming that the number is 9, the filter 33 is attached to the opening 29.
No dust entered and the ink could be stably discharged from the sub tank 2.

[0029]

As described above, according to the present invention, a negative pressure that expands and contracts due to the supply and discharge of a fluid is generated inside a sub-tank that supplies ink to a recording head that ejects ink from a nozzle to form an image. Since the part is provided and the negative pressure is generated in the sub tank, the negative pressure can be generated in the sub tank with a simple configuration.

Further, the sub tank is provided with an atmosphere opening portion for opening the inside of the sub tank to the atmosphere, a negative pressure generating portion provided inside the sub tank for expanding and contracting by supplying and discharging a fluid, and supplying ink from the main tank. When the ink is supplied from the main tank to the sub tank, the inside of the sub tank is opened to the atmosphere by the atmosphere opening part.
After expanding the negative pressure generating part to supply ink from the ink supply part to the sub tank and replenishing the ink in the sub tank,
By shutting off the atmosphere opening portion and contracting the negative pressure generating portion, negative pressure can be reliably generated in the sub tank.

Further, the negative pressure generating portion is expanded and contracted by supplying and discharging the ink to generate the negative pressure, so that it is possible to prevent the ink which is supplied and used for printing from being adversely affected.

Further, by switching the ink supplied to the negative pressure generating section and the ink supply section by the ink flow path switching member, the negative pressure can be generated in the sub tank with a simple structure.

Further, by providing the sub-tank with a negative pressure adjusting section for adjusting the internal negative pressure by passing only the air without passing the ink, the negative pressure in the sub-tank containing the ink can be always kept constant. By forming the negative pressure adjusting portion with a porous body, clogging can be prevented and the function can be stably exhibited for a long period of time.

Further, by providing the sub-tank with a member for preventing the negative pressure generating portion from collapsing, it is possible to prevent air bubbles from staying in the ink due to the air from the negative pressure adjusting portion, and to supply the ink containing no bubbles to the recording head. Therefore, stable printing can be performed.

Further, a filter for filtering the outside air is provided in the atmosphere opening portion, and when the sub tank is opened to the atmosphere by the atmosphere opening portion, dust contained in the atmosphere is prevented from entering the sub tank and is supplied to the recording head. Prevents ink from containing dust.

The sub-tank of this ink supply device is mounted on the carriage together with the recording head for ejecting ink from the nozzles to form an image, and the main tank is installed on the main body, so that a small sub-tank is mounted on the carriage. The carriage can be scanned at high speed, and the printing speed can be increased. Further, the main body is provided with a large-capacity main tank, the frequency of replacement of the main tank can be reduced, and usability can be improved.

[Brief description of drawings]

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

FIG. 2 is a configuration diagram of an ink supply device.

FIG. 3 is a cross-sectional view showing a configuration of a sub tank.

FIG. 4 is a process diagram showing an operation when ink is supplied to a sub tank.

FIG. 5 is a cross-sectional view showing a second configuration of the sub tank.

FIG. 6 is a process diagram showing an operation when ink is supplied to the sub tank of the second configuration.

FIG. 7 is a side sectional view of a sub tank.

FIG. 8 is a partial cross-sectional view showing a second configuration of the atmosphere release valve.

FIG. 9 is a partial cross-sectional view showing a third configuration of the atmosphere release valve.

FIG. 10 is a cross-sectional view showing a third configuration of the sub tank.

[Explanation of symbols]

1; inkjet printer, 2; sub tank, 3; recording head, 4; carriage, 11; main tank, 1
2; ink supply tube, 13; recording paper, 21; ink supply unit, 22; atmosphere open valve, 23; ink remaining amount detection sensor, 24; replenishment completion sensor, 25; negative pressure adjustment unit, 26;
Negative pressure generating part, 27; First ink supply pipe, 28; Pump, 29; Opening part, 30; Seal part, 31; Spring mechanism,
32; pressing mechanism part, 33; filter, 34; second ink supply pipe, 35; pump, 36; bag member.

Claims (9)

[Claims] 1. An ink supply device having a sub-tank for supplying ink to a recording head for ejecting ink from a nozzle to form an image, and a main tank provided independently of the sub-tank for supplying ink to the sub-tank. An ink supply device characterized in that a negative pressure generating portion that expands and contracts by supplying and discharging a fluid is provided inside the sub-tank. 2. An ink supply device having a sub-tank for supplying ink to a recording head which ejects ink from a nozzle to form an image, and a main tank which is provided independently of the sub-tank and supplies ink to the sub-tank. The sub-tank has an atmosphere opening portion that opens the inside of the sub-tank to the atmosphere, a negative pressure generating portion that is provided inside the sub-tank and expands and contracts by supplying and discharging a fluid, and an ink that supplies ink from the main tank. When supplying ink from the main tank to the sub-tank, it has an atmosphere opening part to open the inside of the sub-tank to the atmosphere and expands the negative pressure generating part to supply ink from the ink supply part to the sub-tank. After refilling the ink with the ink, shut off the atmosphere opening part and contract the negative pressure generating part to generate negative pressure in the sub tank. The ink supply device according to symptoms. 3. The ink supply device according to claim 1, wherein the negative pressure generating portion is expanded and contracted by supplying and discharging ink. 4. The ink supply device according to claim 3, wherein the ink supplied to the negative pressure generation section and the ink supply section is switched by an ink flow path switching member. 5. The ink supply device according to claim 1, wherein the sub-tank is provided with a negative pressure adjusting section that adjusts the negative pressure inside by passing only air without passing ink. 6. The ink supply device according to claim 5, wherein the negative pressure adjusting portion is formed of a porous body. 7. The ink supply device according to claim 1, wherein the sub-tank has a member for preventing the negative pressure generating portion from collapsing. 8. The ink supply device according to claim 1, wherein a filter for filtering outside air is provided in the atmosphere opening portion. 9. A sub-tank of the ink supply device according to claim 1, wherein the sub-tank is mounted on a carriage together with a recording head that ejects ink from a nozzle to form an image, and the main tank is installed in the main body. An inkjet recording device characterized by the above.