JP3307601B2 - INK JET RECORDING APPARATUS AND SUB-TANK DEPRESSION CONTROL METHOD IN THE APPARATUS - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head mounted on a carriage and driven reciprocally in the width direction of recording paper;
An ink jet recording apparatus, comprising: a sub-tank for supplying ink to the recording head, the sub-tank being in communication with a negative pressure generating unit to be in a decompressed state, and a decompression control unit for supplying ink from the main tank into the sub-tank; The present invention relates to a method for controlling pressure reduction of a sub tank in the same device.

[0002]

2. Description of the Related Art Ink jet recording apparatuses have been used in many types of printing including color printing in recent years, since noise at the time of printing is relatively small and small dots can be formed at a high density. Such an ink jet recording apparatus is generally mounted on a carriage and moves in the width direction of a recording sheet, and an ink jet recording head;
Paper feed means is provided for moving the recording paper relative to the recording head. Recording is performed by ejecting ink droplets on the recording paper while moving the recording head on the carriage in the width direction of the recording paper. Will be

On a common carriage, for example, a black recording head for discharging black ink and a color recording head for discharging each of yellow, cyan, and magenta inks are mounted. Instead, full-color printing is made possible by changing the ejection ratio of each ink.

On the other hand, in this type of recording apparatus provided for office use or business use, it is necessary to provide a large-capacity ink cartridge in order to cope with a relatively large amount of printing. 2. Description of the Related Art There has been provided a recording apparatus of a type in which a main tank as a cartridge is loaded into a mounting apparatus (cartridge holder) arranged, for example, on a side of an apparatus main body. Then, a sub-tank is arranged on a carriage on which the recording head is mounted, ink is supplied from the main tank to each sub-tank via an ink supply tube, and ink is further supplied from each sub-tank to the recording head. It is configured to be.

[0005]

By the way, in the above-described recording apparatus, ink supply tubes are connected to respective inks in order to supply ink from each main tank to each sub tank. Particularly, in a recording apparatus having a long scanning distance for printing on a large-sized paper surface required recently, there is a problem that the ink supply tube gives resistance to the movement of the carriage.

Therefore, the above-described ink supply tube is eliminated, and when the remaining amount of ink in the sub-tank becomes small,
The present applicant proposes a recording apparatus in which the carriage moves to the ink supply stage, depressurizes the inside of the sub-tank, and supplies ink from each main tank to each sub-tank via a connection mechanism arranged at the location. Have been.

According to this configuration, the ink supply valve is disposed between the sub tank and the recording head. If the pressure in the sub tank is reduced before closing the ink supply valve, the nozzle opening of the recording head is opened. Since the air is sucked from the nozzle, the meniscus formed at the nozzle opening is destroyed, and normal ejection of ink from the recording head becomes impossible. When the ink is supplied to the sub-tank by depressurizing the sub-tank and the ink supply valve is opened immediately thereafter, a phenomenon that the air is similarly sucked in from the nozzle opening of the recording head due to the decompression remaining in the sub-tank occurs. .

Further, when the connection mechanism is separated after the ink is supplied to the sub-tank, the ink leaks in the connection mechanism due to a head difference between the connection mechanism and the main tank, or conversely, the main mechanism is disconnected. This causes problems such as a phenomenon that air flows backward to the tank side.

The present invention has been made in view of such technical problems, and includes the operation timing of the ink supply valve between the sub-tank and the recording head, the timing of the pressure reduction operation of the sub-tank, or the connection timing of the connection mechanism. It is an object of the present invention to provide an ink jet type recording apparatus which solves the above-mentioned problems by setting conditions and the like to specific conditions, and a method for controlling the pressure reduction of a sub tank in the apparatus.

[0010]

Means for Solving the Problems To achieve such a problem
In the present invention in order, and the recording head, and the sub tank for supplying ink to the recording head is supplied with ink from the main tank, the recording heads and the sub-tank
An ink supply valve arranged in a flow path connecting the
Ink jet equipped with carriage equipped with connection mechanism
In the recording apparatus, the carriage is positioned at a predetermined position.
When the main tank is moved,
And the sub-tank, and
And the ink supply valve is closed.
After decompressing the sub tank,
Equipped with a timing control system for supplying ink to the sub tank.

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ink jet recording apparatus according to the present invention will be described based on an embodiment shown in the drawings. FIG. 1 is a sectional view showing the configuration of a sub-tank and a connection mechanism on the sub-tank side in an ink jet recording apparatus to which the present invention is applied. The sub-tank 1 and the connection mechanism 2 attached to the upper part thereof are mounted on a carriage together with a recording head described later.
It is configured to be driven back and forth in the width direction of a recording sheet (not shown). In addition, it is configured such that ink can be supplied from the main tank via the connection mechanism 2 and ink can be supplied to the recording head.

A sub-tank 1 shown in the lower half of FIG. 1 has a case 1a having an open upper part, and a lid 1 for closing the upper part.
b, thereby forming an ink storage chamber 1c whose inside is sealed. In the sub-tank 1, there is disposed a float member 3 that floats with the ink stored in the sub-tank. The float member 3 is configured to be movable up and down in the direction of gravity about a support shaft 4 formed integrally with the float member.

A seal member 5 is arranged above the float member 3. The seal member 5 floats with the ink filled in the sub tank 1, and the air is arranged above the sub tank 1. By contacting the valve member 6 constituting the valve, a suction passage leading to a pressure reducing pump as a negative pressure generating means described later can be closed.

The sub tank 1 is provided with an ink supply port 7 for receiving ink from a main tank, which will be described later, via a connection mechanism 2 shown in the upper half. An ink supply port 8 for supplying ink to a recording head described later is also provided. Further, an air inlet 9 is disposed above the sub-tank 1 so that air can be introduced from the air inlet 9 in response to consumption of ink during printing.

Although FIG. 1 shows the structure of one sub-tank, a plurality of (six in the present embodiment) identical sub-tanks are arranged in the vertical direction on the paper in correspondence with each ink to be handled. The sub-tank of the configuration is provided in a side-by-side manner.

On the other hand, a common valve unit 11 connected to the decompression pump side via a suction space (hereinafter also referred to as a suction port) 10 communicating with the valve member 6 is arranged in the connection mechanism 2. The suction space 10 is formed in a direction perpendicular to the paper surface so as to be transversely communicated with each sub-tank. Therefore, the suction space 10 is disposed on the ink supply stage via a common valve unit 11. It is configured so that it can be connected to another connection mechanism described later. The valve unit 11 is configured to open when it is connected to another connection mechanism disposed on the ink supply stage.

A supply space 12 for feeding ink to the ink supply port 7 is separately formed in the connection mechanism 2 so as to correspond to each sub-tank 1, and a valve unit arranged in each supply space 12 is provided. It is configured such that it can be connected to another connection mechanism, which will be described later, disposed on the ink supply stage through the connection 13. Note that each of the valve units 13 is also configured to open when connected to another connection mechanism arranged on the ink supply stage.

In the connection mechanism 2, in the ink supply path from the ink supply port 8 to the recording head, ink supply valves 14 whose opening and closing are controlled are individually arranged corresponding to the respective sub-tanks. Further, in the connection mechanism 2, air introduction valves 15 that are opened and closed so as to face the above-described air introduction ports 9 are individually arranged corresponding to the respective sub-tanks, and air introduction through the air introduction valves 15 is performed. The space 16 is formed to communicate transversely, and although not shown in FIG. 1, a part of the air introduction space 16 is open to the atmosphere.

Between the sub-tank 1 and the connection mechanism 2, a connection pipe 17 extending integrally from the sub-tank 1 side is formed on the connection mechanism 2 side, for example, as shown by the configuration of the ink supply port 8 portion. It is connected so as to be press-fitted into an annular flexible seal member 19 arranged in the concave portion 18. This configuration is similarly applied to the ink supply port 7, the valve member 6, and the air inlet 9 described above.

In the embodiment shown in FIG. 1, a projection 20 is provided on one side wall of the sub-tank 1.
Enters into an engagement hole 21 formed in the connection mechanism 2, while a projection 22 formed on the other side wall of the sub-tank 1
In addition, the two are integrally connected such that the engaging claw 23 formed on the connection mechanism 2 gets over.

FIG. 2 is a schematic diagram showing a basic configuration of one ink supply system for supplying ink from a ink cartridge serving as a main tank to a recording head via the above-described sub-tank. 2, the connection mechanism 2 on the sub-tank side shown in FIG. 1 and a connection mechanism in an ink supply stage to be described later connected to this connection mechanism are omitted.

Reference numeral 31 in FIG. 2 indicates a main tank, and the main tank 31 is loaded into, for example, a cartridge holder arranged on both outer sides of the recording apparatus.
The ink is supplied to the sub-tank 1 mounted on the carriage via the ink supply path 32. Also, as shown in FIG. 1, the sub-tank 1 is configured to supply ink to the recording head 33 via an ink supply valve 14, and the sub-tank 1 further includes a valve member 6 disposed inside. Is connected to a decompression pump 35 as a negative pressure generating means via a common suction path 34 communicating with the pump.

As schematically shown in FIG. 2, in this configuration, the ink outlet 31a of the main tank 31 is
Both are arranged at a position lower in the direction of gravity with respect to the ink supply port 7 arranged in the sub-tank, in other words, at a negative pressure at the ink supply port 7. With such a configuration, it is possible to prevent the leakage of the ink in the connection mechanism arranged on the ink supply stage.

Next, FIG. 3 shows the structure of a connection mechanism interposed between the main tank 31 and the sub tank 1. FIG. 3 illustrates the six sub-tanks 1 and the connection mechanism 2 on the sub-tank side respectively disposed therein and the connection mechanism 41 on the ink supply side disposed on the ink supply stage. That is, FIG. 3 shows a state viewed from a direction orthogonal to FIG.

The connection mechanism 41 on the ink supply side is configured to be vertically movable by four guide projections 43 arranged inwardly on the guide case 42. The connection mechanism 41 is a connection mechanism described later. It is moved up and down within a predetermined range by a drive motor. A connection opening 44 is formed at the upper end of the connection mechanism 41, and the connection opening 44 has an ink supply path 32, one end of which is connected to each of the main tanks 33 storing the six colors of ink. Are connected to each other. And at each lower end of the connection mechanism 41,
The valve unit 51 described in FIG. 4 and subsequent figures is arranged.

On the other hand, the connection mechanisms 2 are also arranged on the respective sub-tank 1 sides as described in FIG. 1, and the valve units 13 described in FIG. ing. Although not shown in the drawing, the pressure reducing pump 35
A suction path connection mechanism for connecting or disconnecting between the suction path 34 and the suction port 10 is mounted, and this connection mechanism is also configured to be connected or released by a drive motor.

FIGS. 4 to 6 are sectional views showing the configuration of the valve unit in the connection mechanism 41 disposed on the ink supply stage and the valve unit disposed on the sub tank 1 side. 4 shows a state in which both of the valve units are separated, FIG. 5 shows a state in which they are connected, and FIGS. 6 (A) and (B) show FIGS.
2A and 2B are sectional views as viewed in the directions of arrows, respectively.

First, the valve unit 51 on the ink supply stage side has its outer shell formed by joining first and second cylindrical cases 52 and 53 in the axial direction, and an O-ring is provided between the two. 54 are arranged, and the joint is airtight. An opening 5 formed at the upper end in the figure
5 is connected to the main tank 31 via the connection mechanism 41.

An abutting bar 56 having a convex portion 56a formed on the connection end face side is slidably disposed in the axial center portion of the cylindrical cases 52 and 53 so as to be slidable in the axial direction. The protrusion 56a of the abutment rod 56 is urged by a coil spring 57 disposed between the flanged portion and the second case 53 so as to protrude toward the connection end surface (downward in the drawing).

A part of the abutting rod 56 has a tapered portion 56
The taper portion 56b is formed so that the inclined surface of the tapered portion 56b abuts on the seal member 58 when the abutting rod 56 projects. Therefore, in the state shown in FIG.
The slope comes into contact with the seal member 58, and sufficient confidentiality can be secured.

Further, a part of the seal member 58 is integrally extended to the end face side, and in a state where both of the valve units shown in FIG. 5 are connected, each valve unit is extended by the extension part 58a on the end face side. Is configured to be sealed. With such a shared configuration, the number of parts of the seal member 58 can be reduced to one.

On the other hand, the valve unit 13 on the sub tank side
In this case, the outer shell is formed by joining the first and second cylindrical cases 61 and 62 in the axial direction, and an O-ring 63 is arranged between the two cases to make the joint portion airtight. I have. An opening 6 formed at the lower end in the figure
4 communicates with the sub-tank side.

An abutting rod 65 having a convex portion 65a formed on the connection end face side is disposed at the axial center of the cylindrical cases 61, 62 so as to be slidable in the axial direction. The convex portion 65a of the abutment rod 65 is urged by a coil spring 66 disposed between the flange portion and the second case 62 so as to protrude toward the connection end surface (upward in the drawing).

An annular flat plate-shaped sealing member 67 is attached to a flange formed on the abutting rod 65, and the sealing member 6 is energized by the coil spring 66.
7 is configured to abut on the inner wall surface of the cylindrical case 61 to secure confidentiality. Further, in the protruding state of the abutting rod 65 shown in FIG. 4, the connecting surfaces in the axial direction between the abutting rod 65 and the cylindrical case 61 are in close contact with each other at the connection end face, and the gap between the two is reduced. It is configured not to occur. With this configuration, it is possible to effectively prevent ink from remaining on the bonding surface.

FIG. 5 shows a state in which both the valve unit 51 and the valve unit 13 are connected, and this shows that the spring forces of the coil springs 57 and 66 disposed on both are substantially balanced. Is desirable. Since the spring forces of the two are almost balanced, the abutment rods 56 and 65 move almost simultaneously and with the same amount of movement, and an ink flow path is formed between each other.

On the other hand, FIG.
As shown in (A), three protrusions 56c are formed in the circumferential direction of the flange between the flange of the abutment rod 56 of the valve unit 51 and the case 52, so that the axial direction is increased. It is slidably supported, thereby forming an ink flow path. As shown in FIG. 6B, which is a cross section taken along the line BB in FIG. 5, the abutment rod 56 can be slid in the axial direction by four fin-shaped members 52a projecting in the axial direction of the case. Supported, thereby forming an ink flow path.

In this embodiment, four fin-shaped members 52a are formed. However, by forming at least three or more fin-shaped members 52a, the abutting rod 56 can be held at the axial center position. it can. The embodiment shown in FIG. 6 can also be employed in the valve unit 13 on the sub tank side. The valve unit 51 arranged on the ink supply stage side and the valve unit 13 arranged on the sub tank side can be used without any trouble even if they are interchanged.

In the above-described configuration, when the ink amount in the sub tank 1 shown in FIG. 1 decreases due to the continuation of the printing operation and the ink end state is reached, the float member 3 is brought into a state of sinking via the shaft 4. . Then, the carriage moves to the ink supply stage, and as shown in FIG. 3, the connection mechanism 2 on the sub tank side and the connection mechanism 41 on the ink supply side arranged on the ink supply stage are connected.

Although not shown in the drawing, the suction port of the valve member 6 is connected to the decompression pump 35 through a similar connection mechanism.
Is connected to the suction path 34 leading to In this state, the ink supply valve 14 from the sub tank 1 to the recording head 33 is closed, and the air introduction valve 15 is also closed.

As a result, the abutment rods 56, 65 of the respective valve units 51, 13 shown in FIGS. 4 to 6 are moved to a state where the ink can flow. On the other hand, the float member 3
Is located away from the valve member 6, the sub-tank 1 is depressurized by the operation of the decompression pump 35. Therefore, ink is supplied from the ink tank 31 into the sub tank 7 via the valve units 51 and 13.

In this manner, when the ink is supplied from the ink tank 31 into the sub-tank 1 and the ink in the sub-tank 1 is almost full, the float member 3 floats with the ink, and The seal member 5 contacts the valve member 6 to close the air valve. At this time, the seal member 5 is sucked by the pressure reducing pump 35 and comes into close contact with the valve member 6, and the pressure reduction in the sub tank 1 is stopped. Therefore, the ink tank 31
Also, the supply of ink into the sub tank 1 is stopped.

When all the sub-tanks are filled with ink, the connection mechanism 41 disposed on the ink supply stage and the connection mechanism 2 disposed on the sub-tank are disconnected. As a result, the valve units 51 and 13 disposed on the connection mechanism 41 disposed on the ink supply stage and the connection mechanism 2 disposed on the sub tank are separated. Therefore, as described above, the respective abutting rods 56, 65 arranged in the respective valve units 51, 13 are returned to the original state by the urging forces of the respective coil springs 57, 66, and the ink supply paths in the respective valve units 51, 13 Is closed.

Thus, it is possible to prevent the ink from leaking from the connection ends of the valve units 51 and 13. Then, in this state, the ink supply valve 14 from the sub tank 1 to the recording head 33 is opened, and the air introduction valve 15 is also opened, and printing by the recording head 33 is started.

As described above, when the printing operation is performed by the recording head 33 and the amount of ink in the sub-tank 1 is reduced, the ink is supplied at the ink supply stage by the same operation as described above, and the recording head is again operated. The printing operation by 33 is executed.

FIG. 7 shows the ink supply valve 1 described above.
4, a block diagram showing a basic configuration of a control circuit for controlling the operation of the air introduction valve 15, the pressure reducing pump 35, the ink supply path connecting mechanism 41 and the like as time passes. This control circuit is provided with a timing control device 71, which controls the air introduction valve control device 72, the pressure reduction pump control device 73, the suction path control device 74, the ink supply path control device 75, and the ink supply valve. Each of the control devices 76 is configured to be supplied with a command signal.

The air introduction valve control device 72 receives the command and controls the air introduction valve 15 to open or close, and the pressure reduction pump control device 73 receives the command and drives or stops the pressure reduction pump 35. It is configured to control. In addition, the suction path control device 74 includes a suction path connection mechanism 8 that connects or disconnects between the vacuum pump 35 and the suction port 10.
1 is controlled to a connected state or a separated state, and the ink supply path control device 75 controls the ink supply path connecting mechanism 14 to a connected state or a separated state with respect to the sub-tank side. Then, the ink supply valve control device 76
Controls the ink supply valve 14 to open or close.

First, when the sub-tank is in the ink end state and the sub-tank is filled with ink, the timing control unit 71 controls the ink supply valve control unit 7.
A control signal is sent to the pressure reducing pump control device 73 after a predetermined time has passed. Thus, after the ink supply valve 14 is closed, the driving of the pressure reducing pump 35 is started. By performing such control, the ink supply valve 14 is already closed before the pressure in the sub-tank 1 is reduced by driving the pressure reducing pump 35, so that air is sucked in from the nozzle opening of the recording head. The problem of destroying the meniscus formed at the nozzle opening can be prevented.

In this case, by sending a connection command to the suction path control device 74 after a lapse of a predetermined time, the pressure in the sub tank 1 is similarly reduced. In this case, the ink supply valve 14 is already closed. Is controlled,
Therefore, it is possible to prevent the problem of sucking air from the nozzle openings of the recording head.

Further, when the filling of the ink in the sub tank is completed, a valve opening command is sent from the timing control device 71 to the air introduction valve control device 72, and the valve is opened to the ink supply valve control device 76 after a predetermined time has elapsed. Control to send a command. As a result, the air introduction valve 15 is opened first, and the reduced pressure remaining in the sub-tank is canceled to reach the atmospheric pressure. Since the ink supply valve 14 is opened, the problem of sucking air from the nozzle opening of the recording head can be similarly prevented.

In this case, the decompression pump 35 is also stopped by sending a drive stop signal to the decompression pump control device 73 first without sending a valve opening command to the air introduction valve control device 72, so that the predetermined time can be reduced. During the lapse of time, the pressure reduction remaining in the sub tank via the pressure reduction pump 35 is eliminated, and the pressure becomes the atmospheric pressure. Then, since the ink supply valve 14 is opened thereafter, the problem of sucking air from the nozzle opening of the recording head can be similarly prevented.

On the other hand, as described in the above embodiment, the ink lead-out section 31a of the main tank 31
In a case where the ink supply port 7 is arranged at a position lower in the direction of gravity with respect to the ink supply port 7 arranged in the sub tank, it is preferable to execute the following control timing.

That is, the separation control signal is sent from the timing control device 71 to the ink supply channel control device 75, and control is performed so that a valve opening command is sent to the air introduction valve control device 72 after a predetermined time has elapsed. Thus, the connection mechanism 41 of the ink supply path is separated from the sub tank, and the air introduction valve 15 is opened after a predetermined time has elapsed. Therefore, backflow of air to the main tank can be suppressed.

After a lapse of a predetermined time, the suction path control device 7
By sending a separation command to the main tank 4, the backflow of air to the main tank can be suppressed. Further, by sending a drive stop signal to the decompression pump control device 73 after a lapse of a predetermined time, the backflow of air to the main tank can be similarly suppressed.

[0065]

As is apparent from the above description, according to the ink jet recording apparatus and the method for controlling the pressure reduction of the sub tank in the apparatus, the operation timing of the ink supply valve between the sub tank and the recording head, the sub tank The pressure reduction operation timing of the ink supply connection mechanism or the connection timing of the ink supply connection mechanism is controlled in a specific order along the passage of time. Therefore, the nozzle in this type of recording apparatus that supplies ink by reducing the pressure of the sub tank is used. Problems such as suction of air from the opening or backflow of air to the main tank can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a sub tank and a connection mechanism in an ink jet recording apparatus to which the present invention is applied.

FIG. 2 is a schematic diagram illustrating a configuration of an ink supply system from a main tank to a recording head.

FIG. 3 is a side view illustrating a configuration of a connection mechanism disposed on an ink supply stage.

FIG. 4 is a cross-sectional view showing an embodiment of a valve unit arranged in a connection mechanism.

FIG. 5 is a sectional view showing a state where the valve unit is connected.

FIG. 6 is a cross-sectional view of the valve unit as viewed in the direction indicated by arrows from lines AA and BB in FIG.

FIG. 7 is a block diagram showing a basic configuration of a control circuit that executes pressure reduction control in a sub tank.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Subtank 2 Connection mechanism 3 Float member 5 Seal member 6 Valve member (air valve) 7 Ink supply port 8 Ink supply port 9 Air introduction port 10 Suction space (Suction port) 13 Valve unit 14 Ink supply valve 15 Air introduction valve 31 Main Tank 32 Ink supply path 33 Recording head 34 Suction path 35 Decompression pump (negative pressure generating means) 41 Connection mechanism 51 Valve unit

Claims (9)

(57) [Claims] A recording head, a sub-tank for supplying ink to the recording head by receiving ink from a main tank, an ink supply valve disposed in a flow path connecting the sub-tank and the recording head, In the ink jet recording apparatus having a carriage equipped with a connection mechanism, when the carriage moves to a predetermined position, the connection mechanism connects the main tank and the sub tank, and connects the sub tank to pressure reduction control means. With
An ink jet recording apparatus, comprising: a timing control device that depressurizes the sub tank and supplies ink from the main tank to the sub tank after closing the ink supply valve. 2. The ink jet recording apparatus according to claim 1, wherein the timing control device opens the ink supply valve after the depressurized state of the sub tank is released. 3. The ink jet recording apparatus according to claim 2, wherein the pressure in the sub-tank is reduced by opening an air inlet communicating with the sub-tank. 4. The depressurized state of the sub tank is released after the connection between the main tank and the sub tank by the connection mechanism and the connection between the sub tank and the decompression control unit are released. 4. The ink jet recording apparatus according to 3. 5. A printhead, a sub-tank that receives ink from a main tank and supplies ink to the printhead, an ink supply valve disposed in a flow path connecting the subtank and the printhead, In a method for controlling pressure reduction of a sub tank in an ink jet recording apparatus including a carriage equipped with a connection mechanism, the carriage is moved to a predetermined position, the main tank and the sub tank are connected by the connection mechanism, and the sub tank is An ink jet recording apparatus comprising: a step of connecting to a pressure reduction control means; and a step of, after closing the ink supply valve, depressurizing the sub tank by the pressure reduction control means to supply ink from the main tank to the sub tank. Sub-tank pressure reduction control method. 6. The ink jet printer according to claim 5, further comprising: a step of releasing the reduced pressure state of the sub tank after the sub tank is filled with ink; and a step of opening the ink supply valve after a predetermined time has elapsed. A method for controlling the pressure reduction of a sub-tank in a recording apparatus. 7. A step of moving the carriage to release the connection between the main tank and the sub-tank and the connection between the sub-tank and the decompression control means by the connection mechanism, and a step of releasing the depressurized state of the sub-tank. The pressure reduction control method for a sub tank in the ink jet recording apparatus according to claim 5, comprising: 8. The method according to claim 6, wherein the release of the reduced pressure state of the sub-tank is performed by opening an air introduction port communicating with the sub-tank. 9. The depressurization of the sub-tank in the ink jet recording apparatus according to claim 6, wherein the release of the depressurized state of the sub-tank is performed by stopping the operation of a decompression pump constituting the decompression control means. Control method.