JP2006110901A - Deaeration method of liquid tank and the liquid tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal deaeration method of a liquid tank and the liquid tank enabling the efficiency of holding the liquid to be enhanced by inhibiting the liquid discarded in accompanying the deaeration in the liquid tank and not remaining an air layer therein. <P>SOLUTION: The deaeration method of a subtank 20 for eliminating air from the subtank 20, which has an exhaust valve 39 for opening and closing an opening 35 connectable to a suction pump 48 to eliminate the internal air and internally holds the liquid, includes a process for connecting the suction pump 48 to the exhaust valve 39 which serves as an upper part in the state of eliminating the air in the subtank 20 and driving the suction pump 48 (step S6), a process for sucking the internal air of the subtank 20 and eliminating it by releasing the exhaust valve 39 of the subtank 20 (step S7) after the driving process, a process for closing the exhaust valve 39 after the air eliminating process (step S8) and a process for stopping driving the suction pump 48 after the closing process (step S9). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and a liquid tank for removing air accumulated in a liquid tank that stores ink for forming an image on a print medium and a processing liquid for adjusting printability of ink on the print medium.

  In some ink jet recording apparatuses, a large ink tank (hereinafter referred to as a main tank) is disposed at a position away from the carriage in order to increase the ink capacity without increasing the carriage size. The ink supply method in the ink jet recording apparatus having such a structure includes a tube supply method in which a carriage and a main tank are connected by a tube, and a main tank only when supplying ink to an ink tank (hereinafter referred to as a sub tank) that supplies ink to a recording head. A pit-in supply system that connects sub-tanks is adopted.

  In the sub tank, in order to generate a negative pressure, the ink containing portion is made of an elastic body such as rubber, or an elastic member such as a leaf spring is arranged in the ink containing portion to form a sealed structure and generate a negative pressure by an elastic force. Some have adopted a configuration. The sub-tank having such a configuration discharges ink, and when the ink in the sub-tank decreases, the ink containing portion shrinks.

  The ink jet recording apparatus having the above-described configuration has a problem that if it is left for a long period of time, air gradually enters the ink storage portion of the sub tank, and the negative pressure is relieved.

  Further, in the tube supply method, since the tube must be made of a flexible material, it is inevitable that air gradually enters the tube. In the pit-in supply method, although the flow path length is shorter than that in the tube supply method, it is not possible to completely prevent air from entering the flow channel as in the tube supply method.

  In both the tube supply and the pit-in supply methods, when the ink in the main tank is used up and replaced, the main tank must be attached and detached, and air slightly enters the flow path from the connection portion.

  The air that has entered in this manner gradually accumulates in the sub tank, and as the amount of air increases, the ink capacity that can be accommodated in the sub tank decreases. For this reason, in order to prevent the ink from running out during printing, the supply frequency from the main tank to the sub tank must be increased, or the ink and air must be sucked together from the discharge port by the recovery means and discarded.

  In order to remove air almost completely, the sub-tank must be emptied, which causes a large amount of ink to be discarded. This increases the running cost and the size of the waste ink absorber (the size of the recording device). It imitates such a serious fault.

Therefore, Patent Document 1 discloses a configuration using a recovery pump, a one-way valve, and a water-repellent gas permeable membrane for discharging only air in the ink tank without discharging ink.
JP-A-8-187874

  However, the configuration of the ink tank disclosed in Patent Document 1 is a configuration that stores liquid ink while leaving an air layer sealed from the atmosphere, and therefore, there is a waste in terms of ink storage efficiency.

  Therefore, the present invention provides a liquid tank internal air removal method and a liquid tank that can suppress the liquid discarded with air removal in the liquid tank and can increase the liquid storage efficiency by leaving no air layer. For the purpose.

  The method for removing air from a liquid tank according to the present invention includes an opening / closing means configured to be connected to a negative pressure generating means provided in an image forming apparatus and configured to open and close an opening for removing internal air. In the liquid tank air removing method for removing air from the liquid tank to be held, the negative pressure generating means is connected to the upper opening / closing means in a state where the air in the liquid tank is removed, and the negative pressure generating means is driven. A driving process, an air removing process for opening and closing the liquid tank opening and closing means after the driving process to suck and remove air inside the liquid tank, a closing process for closing the opening and closing means after the air removing process, and a negative after the closing process. And a stopping step of stopping driving of the pressure generating means.

  A liquid tank according to the present invention is configured to be connectable to a negative pressure generating unit provided in an image forming apparatus, and includes an opening / closing unit that opens and closes an opening for removing internal air. The opening / closing means is arranged above the liquid tank.

  According to the present invention, after driving the negative pressure generating means, the liquid tank opening / closing means is opened to suck and remove the air inside the liquid tank, and then the open / close means is closed and then the negative pressure generating means is driven. The air will not flow back into the liquid tank. Therefore, the liquid storage efficiency can be increased by leaving no air layer. In addition, since it is not necessary to discard the liquid along with air removal, it is possible to suppress waste liquid that accompanies air removal in the liquid tank.

An embodiment in which the present invention is applied to an image forming apparatus, particularly an ink jet printer will be described. However, the present invention is not limited to such an embodiment, and these may be further combined or described in the claims of this specification. It can also be applied to other technologies that should be included in the concept of the present invention.
(First Example)
In the present embodiment, an ink jet printer of a system in which a supply path is connected only when ink is supplied from a main tank to a sub tank (referred to as a pit-in supply system in the present invention) will be described as an example.

  1 and 2 are cross-sectional views illustrating a schematic structure of an ink jet printer according to an embodiment of the present invention. The image forming apparatus according to the present embodiment is a serial scan method in which a liquid discharge head moves in the main scanning direction. This is an application example. 2 is a cross-sectional view taken along the line AA in FIG.

  In FIG. 1, the printer main body includes a medium feeding unit 1 that feeds a print medium S, a printing unit 2 that performs a printing operation, an ink supply unit 3 that supplies ink, and the like.

  The plurality of print media S stacked on the installation table 5 are inserted into the insertion port 4a provided in the cover 4 which is the exterior of the printer body, and are discharged from the discharge port 4b. On the inner side of the side plate 6 provided in the cover 4, a mounting base 8, a feeding roller 9 and a guide member 11 are provided. The mounting base 8 constitutes means for mounting the print medium S, and is urged by the spring 7 toward the upper feed roller 9. The feeding roller 9 constitutes a medium feeding unit, and abuts on the uppermost position of the plurality of print media S on the mounting table 8. The guide member 11 guides the single print medium S separated by the separating means 10 toward the print unit 2.

  The photo sensor 12 is for detecting the print medium S passing through the downstream side of the guide member 11. The fed print medium S is transported at a constant speed by a pair of transport rollers 13, and the print medium S after printing an image is transported by a pair of transport rollers 14.

  The carriage 19 is guided by guide members 15 and 16 so as to be movable in the main scanning direction (the width direction of the print medium S) indicated by an arrow B in FIG. The carriage 19 moves in the main scanning direction by the driving force transmitted from the carriage motor 70 via the belt 18 that is stretched between the pair of pulleys 17. The sub tank 20 is a reservoir liquid tank that is mounted on the carriage 19 in a replaceable manner. The inkjet head 20a as a liquid ejection head of the present invention (hereinafter referred to as a print head) ejects ink supplied from the sub tank 20 based on image information.

  In the case of the present embodiment, the sub tank 20 and the print head 20a constitute a head cartridge integrally joined. The sub tank 20 and the print head 20a may be configured separately and may be detachably coupled to each other, or may be individually mountable on the carriage 19.

  The electric wiring board 24 arranged inside the cover 4 is provided with a plurality of operation buttons 23 that penetrate the cover 4 and protrude from the surface thereof. In the control means 25, a microcomputer, a memory, and the like are mounted on a control electrical wiring board disposed inside the cover 4. The control means 25 controls the printer while communicating with the host computer.

  As shown in FIG. 2, the main tank 22 of this embodiment includes a main tank 22Y for yellow ink, a main tank 22M for magenta ink, a main tank 22C for cyan ink, and a main tank 22C for cyan ink. It is divided into a main tank 22B for black ink. Each of the main tanks 22Y, 22M, 22C, and 22B (hereinafter may be collectively referred to as 22) is connected to a corresponding supply joint for each ink color via a corresponding pipe (not shown). (Details will be described later). The sub tank 20 in FIG. 2 is in a position when printing on the print medium S.

  An exploded perspective view of the head cartridge in this embodiment is shown in FIG. The following description will proceed with respect to the sub tank 20Y, but the configurations of the other three color sub tanks are the same. The print head 20a includes a plurality of independent head portions for each ink color, and each head portion has a common ink chamber 31 communicating with the ink supply port 30 of the corresponding sub tank 20 and a plurality of ink droplets for ejecting ink droplets. The discharge port 32 is provided. In an ink passage portion that communicates the common ink chamber 31 and the discharge port 32, a discharge energy generation unit (not shown) that generates energy for discharging ink from the discharge port 32 is provided. The sealing member 43 made of a rubber material seals the ink intake port of the sub tank except when ink is supplied. The guide members 15 and 16 are slidably supported by bearing portions 33 and 34.

  The sub tank 20 has a resin top plate 35, a bottom plate 36, an ink bag 37 formed therebetween, and a stainless plate spring 38 therein. The sub-tank 20 includes an exhaust valve 39 on the top plate 35, an ink intake port 40 on the bottom plate 36, and a flexible exhaust tube 41 connected from the top plate 35 to the vicinity of the discharge port 32. The path from the exhaust valve 39 to the exhaust port 42 is first connected from the exhaust valve 39 to the exhaust tube 41 via a flow path (dotted line) inside the top plate 35, and further exhausted via the flow path of the print head 20a. It is formed so as to reach the mouth 42. The exhaust ports 42 are on the same plane as the discharge ports 32, and one exhaust port 42 is arranged for each color. The flow path to the exhaust port 42 in the print head 20a may be integrated into one exhaust port 42. An electrode (details will be described later) is arranged on the top plate 35 toward the inside of the sub tank 20 to detect ink. The flexible cable 60 is a collection of wiring for controlling signal lines from the electrodes and exhaust valves.

  FIG. 4 is a perspective view of the leaf spring 38. The leaf spring 38 having a substantially elliptical shape when viewed from the side has openings 39a and 39b formed at portions corresponding to the exhaust valve 39 and the ink supply port 30, respectively.

  5 and 6 are front views of the sub tank.

  FIG. 5 shows a state where the sub tank 20 is full of ink. The leaf spring 38 is urged in a direction to widen the space between the top plate 35 and the bottom plate 36, and the negative pressure necessary for printing is obtained so that ink does not leak from the discharge port 32 by the force. The side ink bag 37 is composed of a laminate of an aluminum film and a resin film, a laminate of a plurality of resin films, a film material with a coating that prevents gas permeation, or a thin rubber material. Also good. When ink is discharged from the discharge port 32 and the ink in the sub tank 20 is consumed, the top plate 35 descends toward the bottom plate 36 against the force of the leaf spring 38, the ink bag 37 is folded, and the sub tank 20 is thinned. When the ink is used up to the end, the state shown in FIG. 6 is obtained. At this time, since the exhaust tube 41 is flexible, it is deformed into a U shape in the direction perpendicular to the plane of FIG.

  Next, an actual operation state in the ink jet printer will be described with reference to FIGS.

  FIG. 7 shows a state during printing, FIG. 8 shows a standby state and a power-off state, FIG. 9 shows an ink supply state, and FIGS. Details at each position will be described below.

  The supply joint that can be connected to the ink intake port 40 of each sub tank 20 includes a sealing member 44, a supply pipe 45, a spring 46, and a drive system (not shown). One end of the supply joint is connected to the main tanks 22 </ b> Y, 22 </ b> M, 22 </ b> C, and 22 </ b> B, so that the ink in the main tank 22 can be replenished into the sub tank 20.

  The supply pipe 45 has a shape having an ink supply port 45a on the side surface near the tip, and a sealing member 44 made of rubber is urged upward by a spring 46, and the ink supply port 45a is not used during supply. Is hermetically sealed. The distal end of the supply pipe 45 is closed, and the proximal end side is connected to the main tank 22. A cap member 47 that is vertically movable is connected to a waste ink absorber (not shown) via a suction pump 48. The platen 49 guides the print medium to the image print position by the print head 20a.

  FIG. 7 shows a state during printing, and the alternate long and short dash line indicates the shape of the sub tank 20 when the ink in the sub tank 20 is full, and the ink in the sub tank 20 decreases as the ink in the sub tank 20 decreases as the ink is discharged from the discharge ports 32. The plate 35 gradually descends to a state shown by a solid line. The exhaust valve 39 remains closed during printing.

  FIG. 8 shows a state where the print head 20a has moved to its home position. The cap member 47 is raised and the discharge port 32 of the print head 20a is capped. In this case, the sealing member 44 keeps the ink supply port 45a of the supply pipe 45 closed.

  Basically, most of the inside of the sub-tank 20 is ink and air is small, so that expansion and contraction due to pressure fluctuations in the sub-tank 20 accompanying changes in ambient temperature need not be considered. However, when air is present inside, the volume of the sub tank 20 fluctuates with expansion and contraction, which is absorbed by the deformation of the ink bag 37 made of a film or rubber material, and the exhaust valve 39 remains closed. is there.

  With respect to the print head 20a at the home position, it is possible to maintain a good ink discharge state by a head discharge recovery process (hereinafter simply referred to as a recovery process) that discharges ink that does not contribute to image formation. As the recovery process, the inside of the cap member 47 is brought into close contact with the print head 20a, and the ink is forcibly sucked and discharged from the discharge port 32 by the negative pressure generated by the suction pump 48, or the cap member is discharged from the discharge port 32. 47 includes a process of ejecting ink toward the inside. In the home position, the discharge port 32 as well as the exhaust port 42 are capped by the cap member 47. However, since the exhaust valve 39 remains closed, ink is not sucked through the exhaust valve 39 during the recovery process.

  FIG. 9 shows a state where ink is being supplied from the main tank 22 to the sub tank 20. Ink supply is performed when the ink amount in the sub tank 20 falls below a predetermined amount in any one of the four colors of ink. The number of ejected dots may be counted individually for each color, and the time when any one of the colors reaches the predetermined number of dots may be set as the ink supply time. Alternatively, the photo sensor 12 may be used to set the top plate 35 of the sub tank 20. It may be detected that the position has been lowered to a predetermined position and set as the ink supply timing. The two-dot chain line in the figure is the shape of the sub tank 20 before ink supply.

  When the print head 20a moves to the ink replenishment position, the cap member 47 rises to cover the ejection port 32 of the print head 20a. With the sealing member 44 closing the ink supply port 45a, the supply pipe 45, the sealing member 44, and the spring 46 are raised by an unillustrated lifting mechanism. When the sealing member 43 and the sealing member 44 of the ink intake port 40 of the sub tank 20 come into contact with each other, the spring 46 is compressed thereafter, and the sealing member 44 starts to be lowered relative to the supply pipe 45. The ink supply port 45 a is opened inside the sub tank 20. This is a state where an ink supply path is formed between the sub tank 20 and the main tank 22. At this time, a stopper (not shown) is provided so that the sub tank 20 does not rotate with the guide member 16 as a fulcrum.

  In the configuration of this embodiment, ink supply is started when the ink supply port 45a is opened in the sub tank 20 as shown in FIG. The drive source is a stainless steel plate spring 38 that generates a predetermined negative pressure in the sub tank 20. While the pressure inside the main tank 22 is atmospheric pressure, the pressure inside the sub tank 20 is about −49 Pa to −1961 Pa (−50 to −200 mmAq) depending on the discharge capacity of the head and the specifications of the leaf spring 38. ing. Therefore, when an ink supply path is formed between the main tank 22 and the sub tank 20, ink is supplied to the sub tank 20 due to the pressure difference. A stopper 50 is provided above the top plate 35, and the top plate 35 is configured to stop at the position of the stopper 50. The stopper 50 is in a position not in contact with the top plate 35 shown by a two-dot chain line in FIG. 9 except when ink is supplied. This elevating mechanism may have the same drive source as the supply pipe 45. When ink is supplied and the top plate 35 comes into contact with the stopper 50, the pressure in the sub tank 20 is almost atmospheric pressure. When the stopper 50 is raised from this state, the top plate 35 is generated by the force generated by the leaf spring 38. Rises slightly and generates a predetermined negative pressure at a balanced position. During this time, the exhaust valve 39 remains closed.

  10 and 11 show the state after the start of the air accumulated in the sub tank 20 and after the completion. When the printer is left unused for a long period of time or the main tank 22 is attached or detached, the pipe 45, the flow path from the main tank 22 to the sub tank 20, or the ink bag 37 of the sub tank 20 gradually enters the sub tank 20. Air enters. Further, the air is gradually accumulated in the sub tank 20 by repeating the pit-in supply. FIG. 10 shows a state in which air has accumulated in the sub-tank 20, and a portion indicated by oblique lines 51 on the sub-tank 20 is an accumulated air region.

  As shown in this figure, the print head 20a is located slightly to the left of the home position in FIG. 8, that is, the discharge port 32 is opened, and the cap member 47 is raised at a position where the exhaust port 42 is sealed.

  At this time, the discharge port 32 is in an open state, but the ink in the discharge port 32 is not dried and fixed because it is only for a short period of time when air is vented. If there is any reason why the discharge port 32 must be sealed even during air venting, a dummy cap that communicates with the atmosphere through a small-diameter hole instead of communicating with the suction pump 48 may be provided next to the cap member 47. When the cap member 47 seals the exhaust port 42, the suction pump 48 is first driven while the exhaust valve 39 is closed, and the inside of the flow path up to the front of the exhaust valve 39 is set to a negative pressure. When the pressure in the flow passage becomes lower than the pressure in the sub tank 20, the exhaust valve 39 is opened. The opening timing is determined by the negative pressure arrival time calculated from the volume of the flow passage and the capacity of the suction pump 48, and even after the suction pump 48 is driven for a time to reach a negative pressure larger than the negative pressure in the sub tank 20. It is also possible to provide a means for detecting the pressure in the flow passage and when the detected value becomes larger (more negative) than the negative pressure in the sub tank 20. By such control, the air does not flow back into the sub tank during the air vent, and the negative pressure in the sub tank is not eliminated. Therefore, ink does not flow out from the nozzle.

  Since only the raw ink is present in the sub tank 20 except for the leaf spring 38, the air in the sub tank 20 always exists in the upper part. Further, the exhaust valve 39 is located in the upper part of the sub tank 20 as shown in the figure. Therefore, when the exhaust valve 39 is opened and the suction pump 48 is driven, the air accumulated above the sub tank 20 can be extracted through the exhaust tube 41 and the exhaust port 42. When the air in the sub tank 20 decreases and the electrode 52 formed on the top plate 35 detects ink, the exhaust valve 39 is closed. The closing timing is set based on the suction capability of the suction pump 48 and the length of the electrode 52. When the suction capability (speed) is high, the electrode 52 may be lengthened and the exhaust valve 39 may be closed at the moment of detection. When the suction capability is low, the length of the electrode 52 is arbitrary, and the timing of closing the exhaust valve 39 is also Set it accordingly. In any case, the timing may be set so that the ink does not pass through the exhaust valve 39 and enter the flow path to the exhaust port 42. That way, you don't have to waste ink.

  Moreover, since the electrode 52 and the exhaust valve 39 are provided for each color, individual control of each color is possible. For example, the sub-tank 20 in which no air is accumulated is in a state where the electrode 52 detects ink, and the exhaust valve 39 may be kept closed while the suction pump 48 is driven.

  The configuration of Patent Document 1 is such that the recovery pump removes air through the ventilation membrane and the one-way valve, but the timing for stopping the drive of the recovery pump is not described in detail, and the amount of air to be removed Regardless, the recovery pump is driven for a certain predetermined time.

  Also, the amount of air present in the ink tank is different for each color of ink, and there are some that do not need to discharge air, some that must discharge a large amount of air, and all colors are discharged. The amount of air to be discharged may be small or large, and the time required for discharge varies depending on the time. That is, in the configuration of Patent Document 1, the recovery pump drive time must be set in accordance with the longest time among the various patterns, and there is a problem in that the time during which printing cannot be performed becomes long and the printing speed is hindered. there were.

  On the other hand, in the case of the present embodiment, an operation for sucking and exhausting air is performed for the sub-tank in which air is accumulated, and a suction / exhaust operation is not performed for the sub-tank in which air is not accumulated. Optimal control is possible. That is, according to this embodiment, all the sub tanks 20 can be vented simultaneously, and only the necessary sub tanks 20 can be selectively vented, so that the exhaust process can be completed in a short time.

  When the electrodes 52 of all the sub tanks 20 detect ink and close the exhaust valve 39, the suction pump 48 is stopped and the air venting is finished. Normally, the pressure in the flow path from the sub tank 20 to the exhaust port 42 does not have a value that destroys the ink meniscus of the discharge port 32 while the air venting operation is being performed. And the meniscus pressure resistance value are close to each other, a pressure adjusting means may be provided between the exhaust valve 39 and the exhaust port 42 in advance. For example, a pressure sensor and an opening valve (second opening / closing means) are provided as pressure adjusting means, and when the pressure sensor detects that the pressure in the flow passage has reached a predetermined value, the opening valve is opened, and pressure (negative When the pressure is reduced to some extent, the open valve may be closed. That is, the pressure in the range where the ink near the ejection port 32 does not flow in the direction opposite to the direction in which the ink is ejected from the ejection port 32 can prevent the meniscus from being destroyed. The amount of waste liquid can be reduced.

  In addition, an opening valve made of an elastic material such as rubber is provided as a pressure adjusting means, and the opening valve is closed when the pressure exceeds a predetermined negative pressure due to the elastic force, and the elastic force is overcome when the negative pressure increases. The release valve may be opened.

  FIG. 11 shows a state in which the air venting is finished, that is, a state in which the discharge of the air accumulated in the hatched portion 51 on the sub tank 20 shown in FIG. 10 is finished. If the next print data is received from this state, printing may be started. If printing is not performed, the sub tank 20 and the print head 20a may be moved to the home position in FIG. Alternatively, a sequence may be used in which the ink is always fully supplied after the air is released.

FIG. 12 is an exploded perspective view of the exhaust valve 39. The exhaust valve 39 includes a leaf spring member 39a made of a shape memory material having bent portions at two locations, and a valve member 39b made of a rubber material having a substantially vertically symmetrical shape in the figure. Has been. Leaf spring member 39a titanium - in and punching an alloy of nickel-based, hollow circular, it is obtained by a shape having a bent portion 39a ₁ at a site opposite in the circle. The valve member 39b is sealed portion 39b ₂ of the hollow cylinder are formed respectively on the upper and lower surfaces of the base portion 39b ₁ of the disc-shaped. Exhaust valve 39 is disposed in the opening 35a of the top plate 35 while supporting the lower surface of the base portion 39b ₁ of the valve member 39b at the end of the bent portion 39a ₁ of the leaf spring member 39a (FIG. 13, 14, etc. reference).

The opening / closing control of the exhaust valve 39 in the present embodiment is roughly as follows. The bent portion 39a ₁ is elastically deformed by utilizing the fact that the leaf spring member 39a is energized and the elastic coefficient of the leaf spring member 39a varies due to the resistance heat generated by the energization and the elastic force changes. The bent portion 39a ₁ of the elastic valve member 39b on the bent portion 39a ₁ by deformation opening and closing of the valve by up and down are performed. In this figure and related drawings, the electrical wiring portion of the leaf spring member 39a is omitted.

FIG. 13 is an enlarged view of FIG. 10 with the exhaust valve 39 open, and FIG. 14 is a view showing a state in which the exhaust valve 39 is closed. As shown in FIG. 14, the exhaust valve 39 normally has a disc-shaped base portion 39b ₁ of the valve member 39b in contact with the end of the bent portion 39a ₁ of the leaf spring member 39a, and the valve member 39b is more leaf spring member 39a. Since the elastic force is larger than that, the bent portion 39a ₁ is slightly bent downward, and the end portion of the sealing portion 39b ₂ of the valve member 39b is in close contact with the opening portion 35a of the top plate 35 and the exhaust valve 39 is closed. Is maintained.

As described in the explanation of FIG. 10, the leaf spring member 39a is energized when a predetermined negative pressure is reached in the flow passage up to the exhaust valve 42. The longitudinal elastic modulus (Young's modulus E) of the leaf spring member 39a is increased by 2-3 times due to resistance heat generated by energization. Since the bending amount of the bent portion 39a ₁ is inversely proportional to the longitudinal elastic modulus, it is reduced to 1/2 to 1/3, that is, displaced upward so as to approach a no-load state. As a result, the base portion 39b ₁ of the valve member 39b is pushed up and deformed as shown in FIG. 13, and the distal end portion of the sealing portion 39b ₂ formed on the lower surface side of the base portion 39b ₁ is separated from the opening portion 35a of the top plate 35. Thus, a gap 35b is formed. By forming the gap 35b, the sub-tank 20 is connected to the suction pump 48, and the air accumulated in the sub-tank 20 passes through the gap 35b to the outside through the exhaust tube 41, the exhaust port 42, and the suction pump 48. Discharged. When air is discharged and the ink level rises and the electrode 52 detects ink, the power is turned off to close the exhaust valve 39 and the air venting ends. The timing for closing the exhaust valve 39 is as described above.

  As described above, the exhaust valve 39 of the present embodiment is configured only by the leaf spring member 39a that is a shape memory material and the valve member 39b that is a rubber material, and can be controlled to open and close only by electrical control. It is smaller than a solenoid valve using a solenoid and can be made thinner and requires fewer parts.

  As the shape memory material, any material can be used as long as it has flexibility at a normal temperature and can acquire rigidity by control. In addition to Ti—Ni alloys, there are materials containing polymers such as Cu alloys such as Cu—Zn—Al and Cu—Au—Ni. Moreover, the control can also consider heating a shape memory material by a heating means other than electricity supply.

FIG. 15 shows a bent state of the bent portion 39a ₁ of the leaf spring member 39a. Most dotted 53 on the bent portion 39a ₁ the valve member 39b and shows a yet not unloaded state shape in contact, when in the solid line position of the bottom is pressed by the bent portion 39a ₁ valve member 39b in a state exhaust valve 39 is a closed, the middle dotted line 54 shows the position when that is deformed there bent portion 39a ₁ the valve member 39a while the elastic coefficient energized to the leaf spring member 39a is increased.

  As described above, since the energization control of the exhaust valve 39 (leaf spring member 39a) is performed based on the detection result of the electrode 52 in the sub tank 20, optimal control is individually performed while processing the air accumulated in the sub tanks 20 of all colors together. The generation of waste ink can be suppressed and the processing time can be shortened. Further, since the exhaust process is performed by the suction pump 48 that performs the recovery process of the discharge port 32, even if the ink is sucked together with the air from the exhaust valve 39 for some reason, it flows to the waste ink absorber, so that the outside of the printer. Ink leakage can be prevented.

  It is also conceivable that the printer is left under a high temperature such as in a car under hot weather. If the temperature at this time is equal to the temperature at which the elastic coefficient of the leaf spring member 39a changes, even if the printer is not turned on, the leaf spring member 39a is energized and the valve member 39b is pushed up. The sub tank 20 will be in an open state. However, since the exhaust port 42 is capped by the cap member 47 together with the discharge port 32 as shown in FIG. 8, even if ink leaks from the exhaust valve 39, it flows to the waste ink absorber through the cap member 47. Ink leakage to the outside can be prevented.

  Moreover, you may use the member which cancels the operation | movement of the leaf | plate spring member 39a in such an environment.

16 and 17 are an exploded perspective view and a front view showing an example thereof. A leaf spring member (hereinafter referred to as a cancel spring member) 55 is further added to the leaf spring member 39a and the valve member 39b described in FIG. 12 so as to face the leaf spring member 39a. Like the leaf spring member 39a this cancellation spring member 55 biases the base 39b ₁ below the bent portion 55a ₁ the valve member 39b is formed of a shape memory material. Since the cancel spring member 55 has a smaller plate thickness and width of the bent portion than the plate spring member 39a, the force that can be generated is small. Further, unlike the leaf spring member 39a, the cancel spring member 55 is not electrically connected and is configured such that energization control cannot be performed.

  Normally, when the air is not vented, the combined force of the rigidity of the valve member 39b and the elastic force of the cancel spring member 55 is larger than the elastic force of the leaf spring member 39a. The valve 39 is kept closed.

  As described above, when the exhaust valve 39 is opened to extract air from the sub-tank 20, the elastic coefficient is increased by energizing and heating the leaf spring member 39a or heating by the heating means. A clearance is created between the valve member 39 b and the top plate 35 by overcoming the rigidity and the force of the cancel spring member 55. At this time, the cancel spring member 55 is not energized, and a valve member 39b made of a rubber material having a low thermal conductivity is interposed between the cancel spring member 55 and the leaf spring member 39a, so that the temperature of the leaf spring member 39a rises. However, the heat from the leaf spring member 39a is hardly conducted to the cancel spring member 55, and therefore the temperature of the cancel spring member 55 hardly changes. For this reason, the elastic coefficient of the cancel spring member 55 does not change and remains a so-called “weak spring”.

  On the other hand, the printer may be left at a high temperature to reach a temperature at which the elastic coefficient of the leaf spring member 39a changes. At this time, not only the leaf spring member 39a but also the elastic coefficient of the cancel spring member 55 changes in the same manner, so that the force for biasing downward, that is, the force facing the leaf spring member 39a increases, and the rigidity of the valve member 39b Since the resultant force is greater than the force of the leaf spring member 39a, the tip of the valve member 39b is in close contact with the top plate 35 and maintains a sealed state.

That is, if the elastic force of the leaf spring member 39a is Fa (when energized, the temperature rises Faa), the elastic force of the valve member 39b is Fb, and the elastic force of the cancel spring member 55 is Fc (when the temperature rises Fcc),
Fa <Fb + Fc when not venting in normal environment
When the leaf spring member 39a is energized to remove air, Faa> Fb + Fc
When the ambient temperature reaches the temperature at which elastic deformation occurs, Faa <Fb + Fcc
The shape and material of each member may be set so that

  Next, the timing for performing air venting will be described.

  This is determined by the elapsed time since the previous air bleed in the same way as the normal recovery process. This elapsed time is determined at the design stage in consideration of the gas permeability of the material constituting the flow path through which the ink passes, the sub tank 20, and the supply joint. Further, a switch such as an “air vent switch” may be provided so that the user can vent the air at an arbitrary timing.

  The ink flow path between the main tank 22 and the sub tank 20 may slightly enter air when the main tank 22 is attached or detached, and when ink is supplied from the main tank 22 to the sub tank 20 after the main tank 22 is attached or detached. The air also enters the sub tank 20. Therefore, the main tank 22 may be attached and detached, and the air may be removed after the ink is supplied to the sub tank 20. The air may be removed after the first supply after detachment or after a certain number of times of supply.

  Of course, if the electrodes 52 of the sub-tanks 20 of all colors detect ink even under these timings, the air venting operation is unnecessary, so the air is not vented.

  Also, if the exhaust valve 39 is opened when the printer is placed upside down or tilted greatly under these timings, the ink in the sub tank 20 will flow out and waste ink will increase. To prevent this, the printer is first equipped with a sensor that detects the angle and orientation, and depending on the detection result, the printer main body warns the user with an alarm without venting or the computer connected to the printer. Display a warning on the screen. Also, the printer posture is detected during air venting, and when the posture changes suddenly and the output of the posture detection sensor exceeds a certain predetermined range, the exhaust valve 39 is closed at that time and suction is performed. The drive of the pump 48 is stopped. In any case, when the warning issued on the printer or on the screen is canceled by the user's operation, the process returns to the step of detecting the angle and orientation of the printer by the sensor again.

  The above flow is shown in FIGS.

  FIG. 18 is a flowchart from turning on the power to starting printing.

  When the power is turned on (step S1), first, a control unit (not shown) determines whether or not a predetermined time has elapsed since the previous air venting (step S2).

  If the predetermined time has not elapsed, the presence / absence of a print job is determined (step S10), and printing is started (step S11). If there is no print job, the sub tank 20 is moved to the home position and capped with the cap member 47 (step S14). If the predetermined time has elapsed, it is determined whether the angle / posture of the printer is within a predetermined range (step S3).

  If the angle / posture of the printer is not within the predetermined range, an operation for alerting the user, such as a warning by an alarm or a warning on a monitor of a personal computer, is performed (step S12). The user releases the issued warning (step S13) and returns to step S3. Since the exhaust valve 39 is not opened in such a posture that the ink flows out from the opening 35a by issuing a warning in this way, the amount of waste liquid can be suppressed.

  If the angle / posture of the printer is within the predetermined range, it is subsequently determined whether the electrode 52 has detected ink (step S4). Here, if ink is detected for any of the colors, it is determined that the air removal operation of the sub tank 20 is unnecessary, it is determined whether there is a print job (step S10), and printing is started (step S11). If no ink is detected for any of the colors, it is determined that air is in the sub tank 20, the sub tank 20 is moved to the air vent position, and the exhaust port 42 is capped with the cap member 47 (step S5). After capping, first, the suction pump 48 is driven (step S6). Next, the exhaust valve 39 of the sub-tank 20 whose color is not detected is opened (step S7).

  After the air in the sub-tank 20 is removed, the exhaust 39 of the sub-tank 20 whose color is detected is closed (step S8).

  When the exhaust valves 39 for all colors are closed, the driving of the suction pump 48 is stopped (step S9).

  In this way, after the suction pump 48 is driven, the exhaust valve 39 is opened and air is removed. After this operation is finished, the exhaust valve 39 is closed and then the suction pump 48 is stopped. It can be removed and air backflow into the sub tank 20 can be prevented. Therefore, it is possible to prevent ink from flowing out from the ejection port.

  The presence or absence of a print job is determined (step S10), and printing is started (step S11).

  FIG. 19 is a flowchart from when the user operates the air vent switch (in the case of a configuration provided with an air vent switch) to the start of printing.

  When the user turns on the “air vent switch” (step S21), it is determined whether the angle / posture of the printer is within a predetermined range (step S22). The operations after the step of determining the angle / posture of the printer (steps S22 to S33) are the same as (steps S2 to S14) of the flowchart shown in FIG.

  FIG. 20 is a flowchart from the attachment / detachment of the main tank 22 to the start of printing.

The main tank of any color is attached or detached (step S41), and ink is supplied a predetermined number of times from the main tank to the sub tank (step S42). When the ink is supplied a predetermined number of times, it is determined whether or not the printer angle / posture is within a predetermined range (step S43). The operations after the step of determining the printer angle / posture (steps S43 to S54) are the same as (steps S2 to S14) of the flowchart shown in FIG.
(Second embodiment)
In the above embodiment, the sensor detects the angle and orientation of the printer and determines whether or not to perform air bleeding. However, it is also possible to configure the printer with only electrodes.

  FIG. 21 is a perspective view of the sub tank. The same components as those in the first embodiment have the same reference numerals, and the internal leaf spring 38 (see FIG. 3) is omitted. The upper electrode is provided on the top plate 35 at three positions 52a, 52b and 52c, and the lower electrode is provided on the bottom plate 36 at three positions 61a, 61b and 61c. The upper electrodes 52a, 52b, 52c are arranged at an interval of about 120 ° centered on the exhaust valve 39, and the lower electrodes 61a, 61b, 61c are evenly arranged at an interval of about 120 ° centered on the ink supply port 30 to detect ink in the sub tank 20. To do.

  When there is no air in the sub-tank 20 or when there is a minute amount and all the electrodes are in contact with the ink, the upper electrodes 52a, 52b, 52c and the lower electrodes 61a, 61b, 61c are used regardless of the orientation of the printer. Conduction occurs when a voltage is applied between the electrodes and between the upper electrodes. Therefore, the exhaust valve 39 is not opened and air is not vented.

  Next, FIG. 22 shows a flowchart from turning on the power to starting printing.

  When the power is turned on (step S61), first, a control unit (not shown) determines whether or not a predetermined time has elapsed since the previous air venting (step S62).

  If the predetermined time has not elapsed, the presence / absence of a print job is determined (step S70), and printing is started (step S711). If there is no print job, the sub tank 20 is moved to the home position and capped with the cap member 47 (step S76). If the predetermined time has elapsed, it is determined whether or not any of the upper electrodes 52a, 52b, 52c of any color has detected ink (step S63).

  If all of the upper electrodes 52a, 52b, 52c are not in contact with ink, it is then determined whether all of the upper electrodes 52a, 52b, 52c of any color have detected ink (step S72). If it is not detected, an operation for alerting the user, such as warning by an alarm or displaying a warning on a monitor of a personal computer, is performed (step S74). The user releases the issued warning (step S75) and returns to step S63. If it is determined in step S72 that all of the upper electrodes 52a, 52b, 52c of any color have detected ink, it is further determined whether all of the lower electrodes 61a, 61b, 61c have detected ink. Judgment is made (step S73). If it is determined that all of the lower electrodes 61a, 61b, 61c have not detected ink, it is determined that the printer is placed upside down, a warning is issued (step S74), and the user releases the warning (step S75). ), The process returns to step S63. If all of the lower electrodes 61a, 61b, 61c detect ink, it is determined that the air removal operation of the sub tank 20 is unnecessary, it is determined whether there is a print job (step S70), and printing is started (step S71).

  In step S63, when it is determined that all of the upper electrodes 52a, 52b, 52c of any color have not detected ink, the sub tank 20 is moved to the air vent position, and the exhaust port 42 is capped with the cap member 47 ( Step S64). After capping, the suction pump 48 is driven (step S65), and then the exhaust valve 39 of the sub-tank 20 in which no ink is detected is opened (step S66).

  Whether the ink is detected by the second electrode even after a predetermined time has elapsed after one of the upper electrodes 52a, 52b, 52c detects ink by opening the exhaust valve 39 and removing air. Is determined (step S67). When ink is not detected by the second electrode, the control means determines that the printer is tilted greatly, closes the exhaust valve 39, issues a warning (step S74), and after the user cancels the warning (step S75), The process returns to step S63. On the other hand, if ink is detected by the second electrode, after exhausting, the exhaust valves 39 for all colors are closed (step S68). The predetermined time is set in advance depending on the electrode arrangement, the pump capacity, and the like. When the printer is placed substantially horizontally, the three upper electrodes 52a, 52b, 52c of the sub tank 20 are in contact with the ink almost simultaneously, so that the predetermined time need not be set so long.

  All the upper electrodes 52a, 52b, 52c close the exhaust valves 39 of the sub-tank 20 of the color in which the ink is detected (step S68), and when the exhaust valves 39 of all the colors are closed, the driving of the suction pump 48 is stopped (step S68). In step S69, it is determined whether there is a print job (step S70), and printing is started (step S71).

  As described above, only when it is detected that the upper electrodes 52a, 52b, and 52c are not in contact with ink, air is vented, one electrode detects ink, and the second and subsequent electrodes detect ink after a predetermined time has elapsed. If not, the exhaust valves 39 of all the sub tanks 20 are closed so that the ink does not flow out from all of the plurality of sub tanks 20 during air venting, so that the amount of waste liquid from each sub tank 20 can be suppressed.

  Since the lower electrodes 61a, 61b and 61c are also provided at the lower part of the sub tank, the printer can cope with the case where the printer is upside down, so that it can be used for venting the sub tank of the mobile printer which can be placed in various postures. .

FIG. 23 is a flowchart from the user operating the air vent switch to the start of printing.
When the user turns on the “air vent switch” (step S81), it is determined whether or not any of the upper electrodes 52a, 52b, 52c of any color has not detected ink (step S82). The operations after the step of determining whether all of the upper electrodes 52a, 52b, 52c have not detected ink (steps S82 to S95) are the same as those of the flowchart shown in FIG. 22 (steps S63 to S76). Therefore, detailed description is omitted.

  FIG. 24 is a flowchart from the attachment / detachment of the main tank 22 to the start of printing.

  The main tank of any color is attached or detached (step S101), and ink is supplied a predetermined number of times from the main tank to the sub tank (step S102). When the ink is supplied a predetermined number of times, the operation after the step (steps S103 to S116) for determining whether all of the upper electrodes 52a, 52b, 52c have not detected the ink (steps S103 to S116) is shown in the flowchart of FIG. (S63 to S76), the detailed description is omitted.

The upper electrodes are preferably arranged close to each other so as not to leave air in the sub tank 20 as much as possible. The number of electrodes is not limited to three for both the top plate and the bottom plate, and may be arranged as necessary.
(Third embodiment)
In the above-described embodiment, the plate spring member 39a and the cancel spring member 55 are configured by punching a plate-shaped shape memory material, but may be configured by a coil spring.

  25 and 26 show cross-sectional views thereof, and electrical wiring is omitted.

  The exhaust valve 39 of this embodiment includes a valve member 56 made of a rubber material and a coil spring 57 made of a general material such as a stainless steel wire. The coil spring 57 has an open spring 58 and a cancel spring 59 made of a shape memory material as in the first embodiment.

  FIG. 25 shows a state in which the exhaust valve is closed. Since the resultant force of the coil spring 57 and the cancel spring 59 is larger than the force of the release spring 58, the valve member 56 is urged downward to seal the opening 35a of the top plate 35. ing.

  FIG. 26 shows a state in which the exhaust valve 39 is opened. At this time, when the opening spring 58 is energized and the elastic coefficient changes, the elastic force exceeds the combined force of the coil spring 57 and the cancel spring 59 and the valve member 56 is moved upward. The opening 35a of the top plate 35 is opened.

Similar to the first embodiment, the cancel spring 59 is not electrically connected and is configured so that energization control cannot be performed. Even when the open spring 58 is energized, the cancel spring 59 remains a “weak spring”. Similar to the first embodiment, when the printer is left under high temperature such as in a car under the hot sun and the elastic coefficients of the open spring 58 and the cancel spring 59 change, the elasticity of the two springs is not required even when the printer is turned on. The coefficient becomes large. At this time, since the resultant force of the coil spring 57 and the cancel spring 59 is larger than the elastic force of the open spring 58, the exhaust valve is kept closed.
(Fourth embodiment)
In the above embodiment, the printer is a pit-in supply system, but the present invention can also be applied to a tube supply system in which the sub tank and the main tank are always connected by a tube.

  As shown in FIG. 27, there is a system in which an inkjet recording head 1002 and a sub tank 1010 are arranged on a carriage 1001 and sub tank 1010 ink is supplied from a main tank 1003 through a tube 1004. The carriage 1001 is mounted so as to be slidable in the axial direction of the guide shaft 1005. The recording paper 1007 is conveyed by the conveyance roller 1006 and an image is formed by the ink ejected from the inkjet recording head 1002. A cap member 1008 that seals the ejection opening of the inkjet recording head 1002 to prevent drying when the power is turned off or in a standby state is disposed at the home position.

  A valve (not shown) is connected to a portion connecting the tube 1004 and the sub tank 1010 and is closed except when ink is supplied from the main tank 1003 to the sub tank 1010. The configuration and arrangement of the sub tank 1010, the cap member 1008, the exhaust valve, and the suction pump are the same as in the above embodiment.

  In the tube supply system, the tube 1004 must be made of a flexible material, and the amount of air entering from this portion is very large. By repeatedly supplying ink to the sub tank 1010, the air is accumulated in the sub tank.

  The structure, arrangement, control method and operation of the exhaust valve are the same as in the first embodiment. Further, since there is a possibility that the amount of air entering from the tube 1004 is larger than that in the pit-in supply method, the number of air vents may be set larger than that in the pit-in supply method.

  Moreover, the structure which provides a some electrode in a subtank and detects an attitude | position like 2nd Example may be sufficient. In the case of the tube method, most of the electrodes are used on a desktop and are not placed upside down, so the electrodes need only be provided on the top.

  Other than the pit-in supply method and the tube supply method, the method of the present invention can also be applied to an on-carriage supply method that does not have a main tank (a method that replaces the sub tank when ink runs out).

  In each of the above embodiments, the sub-tank is ventilated by using the suction pump of the ink jet recording apparatus main body. However, a configuration in which a dedicated pump for venting air may be provided separately. Providing a dedicated air vent pump enables air to be extracted from the sub tank even when the recording apparatus main body is printing, and the liquid storage efficiency of ink in the tank can be further increased.

1 is a cross-sectional view of a first embodiment of the present invention in which an image forming apparatus is applied to a serial type ink jet printer. It is AA arrow sectional drawing in FIG. FIG. 2 is an exploded perspective view of a sub tank and a head in the embodiment shown in FIG. 1. It is a perspective view of the leaf | plate spring in the sub tank of the 1st Example of this invention. It is a front view of the sub tank of the first embodiment of the present invention in a state where the ink is full. It is a front view of the sub tank of the 1st example of the present invention of the state where ink was used up to the last. It is a figure which shows the state in the middle of printing of the inkjet printer of 1st Example of this invention. It is a figure which shows the state of a sub tank and a head being a standby and power-off. It is a figure which shows the state which supplies the ink from a main tank to a sub tank. It is a figure which shows the state which begins to extract the air accumulate | stored in the subtank. It is a figure which shows the state which finished extracting the air in a subtank. It is a disassembled perspective view of the member which comprises the exhaust valve of 1st Example of this invention. It is a figure which shows the state which the exhaust valve opened in the enlarged view of an exhaust valve periphery. It is a figure which shows the state which the exhaust valve closed in the enlarged view of an exhaust valve periphery. It is a front view of the exhaust valve for demonstrating operation | movement of the bending part of a leaf | plate spring member. It is a disassembled perspective view of the exhaust valve of the other example of the 1st Example of this invention of the structure which considered the temperature rise. FIG. 17 is a front view of the exhaust valve when considering a temperature rise shown in FIG. 16. It is a flowchart of the air bleeding performed after a power supply is turned on until printing starts. It is a flowchart of the air bleed performed after turning on the air bleed switch and starting printing. It is a flowchart of the air bleeding performed after the main tank of any color is attached or detached and it starts printing. It is a perspective view of the sub tank of the 2nd example of the present invention which provided three electrodes up and down. It is a flowchart of the air bleeding using an upper and lower electrode performed by turning on a power supply and starting printing. It is a flowchart of the air bleeding using an upper and lower electrode performed by turning on the air bleeding switch and starting printing. It is a flowchart of the air removal using an upper and lower electrode performed after a main tank of either color is attached or detached and starts printing. It is sectional drawing which shows the state which the exhaust valve of the 3rd Example of this invention using a coil spring sealed the opening part. It is sectional drawing which shows the state which the exhaust valve shown in FIG. 25 opened the opening part. It is a perspective view which shows the schematic structure of the structure inkjet printer of the tube supply system in 4th Example which can apply this invention.

Explanation of symbols

20 Sub tank 39 Exhaust valve 48 Suction pump

Claims (18)

A liquid tank that removes air from a liquid tank that holds liquid therein, and has an opening / closing means that opens and closes an opening for removing the internal air, and is configured to be connectable to a negative pressure generating means provided in the image forming apparatus In the air removal method of
A driving step of connecting the negative pressure generating means to the opening / closing means which is an upper portion in a state where air in the liquid tank is removed, and driving the negative pressure generating means;
After the driving step, an air removing step of opening the opening / closing means of the liquid tank and sucking and removing air inside the liquid tank;
A closing step of closing the opening and closing means after the air removing step;
And a stopping step of stopping driving of the negative pressure generating means after the closing step.   The liquid tank air removing method according to claim 1, wherein the negative pressure generating means is drivable during image formation of the image forming apparatus.   The image forming apparatus includes an angle detection unit that detects an angle of the liquid tank, and the air removal step includes a detection result by a liquid detection unit that detects presence / absence of liquid provided in the vicinity of the opening / closing unit, or the The method for removing air from a liquid tank according to claim 1, wherein the detection results by the means for detecting the angle of the liquid tank provided in the image forming apparatus are performed individually or by using two detection results together.   The liquid tank air removal method according to claim 3, wherein the air removal step is performed when a detection result by the angle detection means is within a predetermined range.   The method for removing air from a liquid tank according to claim 3, wherein the angle detection means also serves as means for detecting the presence or absence of the liquid.   The angle detecting means detects an angle even during the air removing step, and when the detected angle exceeds a predetermined range, the opening / closing means is closed, the driving of the negative pressure generating means is stopped, and the air removing is performed. The method for removing air from the liquid tank according to claim 3 or 5, wherein the process is stopped.   4. The air removal step, wherein a plurality of liquid detection means are provided in the vicinity of the opening / closing means of the liquid tank, and air is removed only when all of the plurality of liquid detection means are not detecting liquid. Or the liquid tank air removal method of Claim 5.   In the air removal step, a plurality of the liquid detection means are provided in the upper and lower portions of the liquid tank, and air is removed only when all of the upper liquid detection means among the plurality of liquid detection means have not detected the liquid. The method for removing air from the liquid tank according to claim 3 or 5, wherein:   A plurality of liquid detection means for detecting the presence or absence of liquid in the vicinity of the opening and closing means, and the second and subsequent ones even after a predetermined time has elapsed since one of the liquid detection means detected liquid in the air removal step; The liquid tank air removing method according to any one of claims 1 to 3, and 5 to 8, wherein when the liquid detecting means detects no liquid, the opening / closing means is closed in the closing step.   In the air removal step, even if a predetermined time has elapsed after one of the plurality of liquid detection means in each of the plurality of liquid tanks detects the liquid, the second and subsequent liquid detection means detect the liquid. The method for removing air from a liquid tank according to claim 9, wherein if not, the open / close means of all the liquid tanks are closed in the closing step.   In a state where at least one of the plurality of liquid detection means does not detect liquid, the air removal step is not performed, a warning from the image forming apparatus, and a warning on the control means to which the image forming apparatus is connected, The method for removing air from the liquid tank according to claim 1, wherein at least one of the steps is performed.   12. The method according to claim 1, further comprising a second air removing step of opening only the opening / closing means of the liquid tank that needs to remove air from a plurality of liquid tanks after the driving step. How to remove air from a liquid tank.   The method for removing air from a liquid tank according to claim 1, wherein the opening / closing means opens and closes by driving a member made of a shape memory material.   The pressure generated when the negative pressure generating means is driven is such that the liquid in the vicinity of the discharge port of the discharge means for discharging the liquid supplied from the liquid tank from the discharge port is the direction in which the liquid is discharged from the discharge port. The method for removing air from a liquid tank according to any one of claims 1 to 13, wherein the pressure is in a range that does not flow in the reverse direction.   A second opening / closing means is provided in a path between the negative pressure generating means and the discharge port of the discharge means for discharging the liquid supplied from the liquid tank from the discharge port, and the negative pressure generating means is driven. The pressure that is sometimes generated reaches the pressure that flows backward with respect to the discharge direction of the liquid from the discharge port, and the second opening and closing means is opened. Air removal method for liquid tanks. In a liquid tank that holds liquid inside, having open / close means configured to be connected to negative pressure generating means provided in the image forming apparatus and opening / closing an opening for removing internal air,
The liquid tank is characterized in that the opening / closing means is disposed corresponding to an opening formed in an upper portion of the liquid tank and has at least one shape memory material for driving the opening / closing means.   17. The liquid tank according to claim 16, wherein the opening / closing means includes an elastic member and the shape memory material in which a bending portion that contacts and drives the elastic member is formed.   The liquid tank according to claim 16 or 17, further comprising at least one liquid detection means for detecting the presence or absence of liquid in the vicinity of the opening / closing means.

Images