A device for dispensing liquid

Abstract

To provide a device for discharging a liquid which enables a recovered liquid to be recycled without increasing the size of the device and the cost.SOLUTION: A device for discharging a liquid includes a liquid discharge head 11 for discharging at least a black liquid, a liquid cartridge 20 for supplying the liquid to the liquid discharge head 11, a maintenance part 10 for performing maintenance of the liquid discharge head 20, a single fixation waste liquid tank 8 for storing a waste liquid discharged from the maintenance part 10, and a route 4 for supplying the waste liquid stored in the fixation waste liquid tank 8 to the liquid discharge head 11 for discharging the black liquid, wherein the fixation waste liquid tank 8 includes means 81 for stirring the stored waste liquid.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an apparatus for discharging a liquid.

Background Art

[0002] In an inkjet recording apparatus as an example of an apparatus for discharging a liquid, ink as the liquid remaining in the nozzles or on the nozzle surface of a liquid discharge head is collected in a waste liquid tank by performing empty discharge or suction.

[0003] Conventionally, the ink discharged into the waste liquid tank has been discarded as it is. There has been a problem that the disposal leads to an environmental load. Also, there has been a problem that the user has to replace the tank for collecting the waste liquid, which results in a cost burden. In response to such problems, a technique for reusing the collected waste ink has been proposed (see, for example, Patent Document 1).

[0004] Patent Document 1 discloses an inkjet recording apparatus provided with means for supplying the ink collected by a collecting means to a recording head for reused ink as reused ink.

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the apparatus of Patent Document 1, since it has a configuration including a recording head dedicated to reused ink, it may lead to an increase in the size of the apparatus and it may be difficult to reduce costs.

[0006] Therefore, an object of the present invention is to provide an apparatus for discharging a liquid that can reuse the collected liquid without causing an increase in the size of the apparatus or an increase in cost.

Means for Solving the Problems

[0007] To solve the above problems, the liquid dispensing apparatus of the present invention comprises a liquid dispensing head that dispenses at least a black liquid, a liquid cartridge that supplies liquid to the liquid dispensing head, a maintenance unit for performing maintenance on the liquid dispensing head, a single fixed waste liquid tank for storing waste liquid discharged from the maintenance unit, and a path for supplying the waste liquid stored in the fixed waste liquid tank to the liquid dispensing head that dispenses a black liquid, wherein the fixed waste liquid tank is equipped with means for agitating the stored waste liquid. The fixed wastewater tank has a longitudinal direction on one side and a short direction on the other side, with an inlet provided above one side in the longitudinal direction for the wastewater to flow in in the longitudinal direction, and an outlet provided below the other side in the longitudinal direction for the wastewater to be discharged in the longitudinal direction, and the inside of the fixed wastewater tank has a first slope that decreases from the inlet side to the outlet side in the longitudinal direction, a second slope that decreases from one outside to the inside when the outlet side in the short direction is considered the inside, and a third slope that decreases from the other outside to the inside. It is characterized by the following: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a device that dispenses liquid that can be reused after being recovered, without increasing the size or cost of the device. [Brief explanation of the drawing]

[0009] [Figure 1] This is an explanatory diagram showing the schematic configuration of the main components of the liquid dispensing device of this embodiment. [Figure 2] This is a schematic diagram showing an example of a fixed waste liquid tank. [Figure 3] This is a schematic diagram showing an example of a fixed waste liquid tank. [Figure 4] This is an explanatory diagram showing the schematic configuration of the main components of the liquid dispensing device of this embodiment. [Figure 5] This figure shows an example of a liquid dispensing device according to this embodiment. [Modes for carrying out the invention]

[0010] The liquid dispensing apparatus according to the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited to the embodiments shown below, and can be modified, added, altered, or deleted to the extent that a person skilled in the art can conceive of it. Any embodiment that achieves the function and effect of the present invention is included within the scope of the present invention.

[0011] Figure 1 is an explanatory diagram showing the schematic configuration of the main parts of one embodiment of a liquid dispensing device according to the present invention. The liquid dispensing device of this embodiment comprises a liquid dispensing head 11, a liquid cartridge 20 for supplying liquid to the liquid dispensing head 11, a maintenance unit for performing maintenance on the liquid dispensing head 11, a fixed waste liquid tank 8 for storing waste liquid discharged from the maintenance unit, and a path 4 for supplying the waste liquid stored in the fixed waste liquid tank 8 to the liquid dispensing head 11. The fixed waste liquid tank 8 is equipped with means 81 for agitating the stored waste liquid.

[0012] The liquid ejection device shown in Figure 1 is, for example, an inkjet recording device and is equipped with multiple liquid ejection heads 11. Each liquid ejection head 11 has multiple nozzle holes opening on its nozzle surface 11a, from which black (Bk), cyan (C), magenta (M), and yellow (Y) inks are ejected.

[0013] The liquid cartridge 20 supplies ink of the corresponding color to the liquid ejection head 11. The liquid cartridge 20 is removable.

[0014] The liquid dispensing device of this embodiment only needs to include a liquid dispensing head 11 that dispenses black (Bk) liquid and a liquid cartridge 20 that supplies black (Bk) liquid, and the presence or type of liquid dispensing head 11 and liquid cartridge 20 of other colors can be selected as appropriate. The stored waste liquid is supplied to a liquid discharge head 11 that discharges a black (Bk) liquid.

[0015] The maintenance unit 10 (see Figure 5) is equipped with a wiper 12, a suction cap 14, a moisturizing cap 16, etc., and performs operations to maintain the normal discharge of the liquid discharge head 11. Figure 1 shows only the suction cap 14. The suction cap 14 is a cap member equipped with a suction mechanism for drawing liquid from the nozzle surface 11a when the liquid discharge head 11 is being maintained.

[0016] During the suction operation by the suction cap 14, it abuts against the nozzle surface 11a of any one of the liquid ejection heads 11 (Bk in FIG. 1) to cover the nozzle holes. In an aspect where a plurality of liquid ejection heads 11 are provided, the suction cap 14 sequentially abuts against the nozzle surfaces 11a of all the liquid ejection heads 11. Also, an aspect in which a plurality of suction caps 14 corresponding to the plurality of liquid ejection heads 11 may be provided.

[0017] On the side of the suction cap 14 opposite to the nozzle surface 11a, a suction pump 6 is connected via a tube 5. With the suction cap 14 attached to the nozzle surface 11a, the suction pump 6 is driven. Thereby, the suction pump 6 sucks the ink remaining in the nozzle and on the nozzle surface 11a, and the sucked ink reaches the fixed waste liquid tank 8 through the connected tube 5 and is stored in the fixed waste liquid tank 8.

[0018] Since the sucked ink contains foreign matters such as dust adhering to the nozzle surface 11a etc., it is preferable to provide a filter member 7 for filtering the waste liquid discharged from the maintenance section on the upstream side of the fixed waste liquid tank 8.

[0019] FIG. 2 is a schematic diagram showing the inside of the fixed waste liquid tank 8, and shows an example of means (hereinafter, also simply referred to as "stirring means") 81 for stirring the stored waste liquid provided in the fixed waste liquid tank 8. In the apparatus of this embodiment including a single fixed waste liquid tank 8, in an aspect where a plurality of liquid ejection heads 11 and liquid cartridges 20 of a plurality of colors in addition to black are provided, the waste liquid discharged from the maintenance section will have black liquid and liquid of other colors mixed therein. On the other hand, by providing the stirring means 81 inside the fixed waste liquid tank 8, the liquids of each color are stirred and become a color close to black as a whole. Also, by performing stirring by the stirring means 81, the occurrence of thickening of the stored liquid can be delayed, and the freshness of the liquid can be maintained.

[0020] As the stirring means 81, a stirring screw as shown in Fig. 2(A) can be used. Examples of the stirring screw include those in which blade-like members such as twisted blades are attached at predetermined intervals to a rotating shaft along the longitudinal direction of the fixed waste liquid tank 8. When the blade-like members rotate, the waste liquid is stirred. Also, the stirring means 81 can be a fan as shown in Fig. 2(B). The drive mechanism of the stirring means 81 is composed of, for example, a motor and a transmission connected to the rotating shaft.

[0021] The drive mechanism of the stirring means 81 is composed of, for example, a motor and a transmission connected to the rotating shaft. The drive mechanism of the stirring means 81 is preferably shared with the drive mechanism of the adjacent suction pump 6. This can reduce the space occupied by the device and lower the cost.

[0022] Fig. 3 is a diagram schematically showing the internal shape of the fixed waste liquid tank 8, and the illustration of the stirring means 81 is omitted. Fig. 3(A) is a cross-sectional view of the side surface in the longitudinal direction of the fixed waste liquid tank 8, and Fig. 3(B) is a cross-sectional view taken along the line X-X of Fig. 3(A). The inside of the fixed waste liquid tank 8 has an inclined portion 8a with a gradient that becomes lower toward the discharge port 8b through which the waste liquid 2 is discharged. The inclined portion 8a is formed in the longitudinal direction and the short side direction, respectively.

[0023] By providing the inclined portion 8a inside the fixed waste liquid tank 8, the waste liquid 2 can be reliably sent out to the discharge port 8b. Also, since air is collected above the discharge port 8b, it is possible to prevent air from being mixed into the discharged waste liquid 2.

[0024] Figure 4 is an explanatory diagram showing the schematic configuration of the main parts of another embodiment of the liquid ejection device according to the present invention. The liquid ejection device shown in Figure 4 is, for example, an inkjet recording device, similar to that in Figure 1, and is equipped with a plurality of liquid ejection heads 11. Each liquid ejection head 11 has a plurality of nozzle holes opening on its nozzle surface 11a, from which black (Bk), cyan (C), magenta (M), and yellow (Y) inks are ejected, respectively.

[0025] In the liquid dispensing device of this embodiment, the fixed waste liquid tank 8 can be provided with a detection means for detecting the characteristics of the stored waste liquid. Examples of waste liquid characteristics to be detected include viscosity, concentration, pH, etc., and can be appropriately selected as needed.

[0026] In the example shown in Figure 4, the fixed waste liquid tank 8 is equipped with viscosity detection means 83 for detecting viscosity. An example of the viscosity detection means 83 is a viscometer. Alternatively, instead of providing the viscosity detection means 83, the output load of the drive mechanism of the stirring means 81 (the output load of the motor) can be used as a substitute value for viscosity.

[0027] In the liquid dispensing device of this embodiment, the fixed waste liquid tank 8 can be provided with a heating means 82 for heating the stored waste liquid. By providing the heating means 82, it is possible to prevent an increase in the viscosity of the waste liquid even in environments where the temperature inside the fixed waste liquid tank 8 is low. The heating means 82 is not particularly limited as long as it can heat to a predetermined temperature, and examples include a heater equipped with an automatic temperature control means such as a thermostat.

[0028] In the example shown in Figure 4, a filter member 7 is provided upstream of the fixed waste liquid tank 8 to filter the waste liquid discharged from the maintenance unit. The fixed waste liquid tank 8 has a slope 8a (not shown) that decreases towards the outlet from which the waste liquid is discharged, and is equipped with a viscosity detection means 83 for detecting the viscosity of the stored waste liquid and a heating means 82 for heating the stored waste liquid.

[0029] Furthermore, in the liquid dispensing device of this embodiment, the device can be configured to include means for detecting deterioration of the waste liquid stored in the fixed waste liquid tank 8, a replacement waste liquid tank 31, and a switching valve 33 for switching the destination of the waste liquid supplied from the fixed waste liquid tank 8 between the replacement waste liquid tank 31 and the liquid dispensing head 11, thereby supplying the liquid in which deterioration has been detected to the replacement waste liquid tank 31. The viscosity detection means 83 described above can be used as a means to detect the deterioration of the waste liquid. Furthermore, as shown in Figure 4, it is preferable to provide a waste liquid suction pump 32 for sucking up the waste liquid in the fixed waste liquid tank 8 upstream of the switching valve 33.

[0030] Depending on the detection results from the means for detecting the deterioration of the waste liquid, it is possible to select whether to reuse the waste liquid in the fixed waste liquid tank 8 or to dispose of it. For example, if viscosity detection means 83 is used as the means for detecting the deterioration of the waste liquid, waste liquid exceeding a predetermined viscosity is deemed unsuitable for reuse and is selected for disposal. If the waste liquid is to be disposed of without reuse, it is supplied to the replacement waste liquid tank 31 and disposed of in the replacement waste liquid tank 31.

[0031] Furthermore, the liquid dispensing device of this embodiment can be configured to include a removable waste liquid storage cartridge 30 for storing waste liquid to be reused, located downstream of the outlet 8b of the fixed waste liquid tank 8. As shown in Figure 4, the waste liquid storage cartridge 30 can be installed between the outlet 8b of the fixed waste liquid tank 8 and the liquid discharge head 11 to which the waste liquid is supplied, that is, on the path 4 that supplies the waste liquid to the liquid discharge head 11.

[0032] The waste liquid storage cartridge 30, once filled to its capacity, can be removed and stored, and can be used, for example, as a recycled cartridge for supplying liquid to the black (Bk) liquid dispensing head 11.

[0033] Figure 4 illustrates an example of the waste liquid recycling process in an inkjet recording device. First, waste liquid discharged by the maintenance unit from each liquid discharge head 11, which dispenses black (Bk), cyan (C), magenta (M), and yellow (Y) inks, is stored in a fixed waste liquid tank 8. The waste liquid stored in the fixed waste liquid tank 8 has its viscosity detected by a viscosity detection means 83 as an indicator of the degree of ink degradation, and a decision is made on whether to reuse or discard it. The waste liquid is sucked into the waste liquid suction pump 32, and the supply destination is switched by a switching valve 33. If discarding is selected, the waste liquid is sent to the replacement waste liquid tank 31. The replacement waste liquid tank 31 is replaceable. On the other hand, if reuse is selected, it is supplied to the liquid ejection head 11 that ejects black (Bk) ink, or to the removable waste liquid storage cartridge 30. When the waste liquid supplied to the waste liquid storage cartridge 30 reaches its capacity, it can be removed and stored, and reused as a recycled part to supply ink to the black (Bk) liquid ejection head 11. Furthermore, the waste liquid stored inside the fixed waste liquid tank 8 is kept fresh by preventing viscosity increase through stirring by the stirring means 81 and temperature control by the heating means 82.

[0034] With the above configuration, the liquid dispensing device of this embodiment allows for the reuse of the recovered liquid without increasing the size or cost of the device.

[0035] An example of an inkjet recording apparatus as a liquid ejection device according to the present invention will be described with reference to Figure 5. Figure 5 shows a serial-type head unit (liquid ejection device). As shown in Figure 5, the inkjet recording device 100 holds the carriage 63 so that it can move in the main scanning direction D1 by a main guide member 61 and a secondary guide member. The main guide member 61 and the secondary guide member are mounted horizontally on the left and right side plates.

[0036] A timing belt 68 is stretched between a drive pulley 66 and a driven pulley 67. When the drive pulley 66 rotates due to the driving force of the main scanning motor 65, the timing belt 68 travels in a circular motion, and the driven pulley 67 rotates in response. This circular motion of the timing belt 68 causes the carriage 63 to reciprocate in the main scanning direction D1 (carriage movement direction).

[0037] The carriage 63 is equipped with a head unit 3 that has multiple liquid ejection heads 11. The liquid ejection heads 11 eject ink droplets of various colors, such as yellow (Y), cyan (C), magenta (M), and black (K). The liquid ejection heads 11 also have multiple nozzle rows 11n, each consisting of multiple nozzles, in the sub-scanning direction D2, which is perpendicular to the main scanning direction D1. Each nozzle opens downwards (from the front side to the back side in the direction perpendicular to the paper surface in Figure 5), and this direction is the droplet ejection direction.

[0038] Furthermore, the inkjet recording device 100 is equipped with a transport belt 69, which is a transport means. The transport belt 69 electrostatically attracts the paper P and transports the paper P in the sub-scanning direction D2 at a position facing the liquid ejection head 11. This transport belt 69 is an endless belt and is stretched between the transport roller 78 and the tension roller 79.

[0039] The driving force of the sub-scanning motor 70 causes the transport roller 78 to travel in a circular motion in the sub-scanning direction D2 via the timing belt 71 and timing pulley 72. As the transport belt 69 moves in a circular motion, it is charged (charged) by the charging roller. The circular motion of the transport roller 78 allows the paper P on the transport roller 78 to be transported in the sub-scanning direction D2.

[0040] Furthermore, the inkjet recording device 100 is equipped with a maintenance unit 10 on one side of the main scanning direction D1 of the carriage 63, next to the transport belt 69. The maintenance unit 10 includes a wiper 12, a suction cap 14, a moisturizing cap 16, and the like.

[0041] The inkjet recording device 100 also has an encoder scale 73 and an encoder sensor 74. The encoder scale 73 is stretched between the side plates of the carriage 63 along the main scanning direction D1 and has a predetermined pattern along the main scanning direction D1. The encoder sensor 74 has a transmissive photosensor and can read this predetermined pattern on the encoder scale 73. Together with the encoder scale 73 and encoder sensor 74, a linear encoder (main scanning encoder) is configured to detect the movement of the carriage 63.

[0042] Furthermore, the shaft of the conveyor roller 78 is equipped with a code wheel 75 having a predetermined pattern formed on it, and an encoder sensor 76. The encoder sensor 76 has a transmissive photosensor and can detect the pattern formed on the code wheel 75. These code wheel 75 and encoder sensor 76 constitute a rotary encoder (sub-scan encoder) that detects the amount of movement and position of the conveyor belt 69.

[0043] In the inkjet recording device 100 configured in this way, when paper P is transported from the paper feed tray, the charged transport belt 69 attracts the paper P to its surface. The transport belt 69 then moves in a circular motion, transporting the paper P in the sub-scanning direction D2. In conjunction with this, the carriage 63 is moved in the main scanning direction D1, and the liquid ejection head 11 is driven according to the image signal, ejecting ink droplets onto the stationary paper P to record one line. After transporting a predetermined amount of paper P, the next line is recorded. Upon receiving a recording completion signal or a signal that the trailing edge of paper P has reached the recording area, the recording operation is terminated and the paper P is ejected into the output tray.

[0044] Furthermore, when cleaning the liquid ejection head 11, the carriage 63 is moved to the maintenance unit 10 while the printer is waiting to print (record), and the maintenance unit 10 performs the maintenance operation. Alternatively, the liquid ejection head 11 may remain stationary, with the maintenance unit 10 moving to perform the maintenance operation.

[0045] "Liquid dispensing devices" include devices that have a liquid dispensing head, liquid dispensing unit, head module, head unit, etc., and drive the liquid dispensing head to dispense liquid. Liquid dispensing devices include not only devices that can dispense liquid onto surfaces to which liquid can adhere, but also devices that dispense liquid into air or into liquid.

[0046] This "liquid dispensing device" may also include means for feeding, transporting, and dispensing paper onto materials to which liquid can adhere, as well as pre-treatment devices, post-treatment devices, etc. Furthermore, "devices that dispense liquid" are not limited to those that visualize meaningful images such as letters or figures through the dispensed liquid. For example, devices that form patterns that do not have meaning in themselves, or devices that create three-dimensional images, are also included.

[0047] The term "materials to which liquid can adhere" above refers to materials to which liquid can adhere, at least temporarily, including materials that adhere and solidify, or materials that adhere and penetrate. Specific examples include recording media such as paper, recording paper, film, and cloth; electronic components such as electronic circuit boards and piezoelectric elements; powder layers; organ models; and inspection cells. Unless otherwise specified, it includes all materials to which liquid can adhere.

[0048] The materials referred to as "materials to which liquid can adhere" above include paper, thread, fibers, fabrics, leather, metal, plastic, glass, wood, ceramics, etc., as long as liquid can adhere to them, even temporarily. Recording media include plain paper (P), as well as cardboard, postcards, envelopes, thin paper, coated paper (such as coated paper and art paper), tracing paper, OHP sheets, plastic film, prepreg, copper foil, and the like.

[0049] Furthermore, "liquid dispensing devices" include devices in which the liquid dispensing head and the surface to which the liquid can adhere move relative to each other, but are not limited to these. Specific examples include serial-type devices in which the liquid dispensing head moves, and line-type devices in which the liquid dispensing head does not move.

[0050] In the terminology used in this application, image formation, recording, printing, copying, printing, and molding are all synonymous. Furthermore, the liquid is not particularly limited as long as it has a viscosity and surface tension that can be discharged from the liquid discharge head, but it is preferable that its viscosity becomes 30 mPa·s or less at room temperature and atmospheric pressure, or when heated or cooled. More specifically, it is a solution, suspension, emulsion, etc., containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a polymerizable compound, a resin, a functional material such as a surfactant, a biocompatible material such as DNA, amino acids or proteins, calcium, or an edible material such as a natural pigment. These can be used, for example, as inkjet inks, surface treatment liquids, liquids for forming components of electronic elements and light-emitting elements or electronic circuit resist patterns, and material liquids for 3D molding.

[0051] Examples of the present invention are as follows: <1> A liquid dispensing head that dispenses at least a black liquid and A liquid cartridge that supplies liquid to the liquid dispensing head, A maintenance unit for performing maintenance on the liquid dispensing head, A single fixed wastewater tank for storing wastewater discharged from the aforementioned maintenance unit, The system includes a path for supplying the waste liquid stored in the fixed waste liquid tank to the liquid discharge head that discharges a black liquid, The aforementioned fixed waste liquid tank is a liquid discharge device characterized by having means for agitating the stored waste liquid. <2> The interior of the fixed waste liquid tank is characterized by having an inclined section that slopes downward toward the outlet from which the waste liquid is discharged. <1> This is a device for dispensing the liquid described above. <3> The aforementioned is characterized by comprising viscosity detection means for detecting the viscosity of the waste liquid stored in the fixed waste liquid tank. <1> or <2> This is a device for dispensing the liquid described above. <4> The aforementioned fixed wastewater tank is equipped with a heating means for heating the wastewater stored in the fixed wastewater tank. <1> from <3> This is a device for dispensing any of the liquids described in the following. <5> The aforementioned fixed wastewater tank is characterized by having a filter member on the upstream side for filtering the wastewater discharged from the maintenance unit. <1> from <4> This is a device for dispensing any of the liquids described in the following. <6> A filter member for filtering the waste liquid discharged from the maintenance unit is provided on the upstream side of the fixed waste liquid tank. The aforementioned fixed waste liquid tank has a slope inside that decreases toward an outlet from which the waste liquid is discharged, and is characterized by comprising viscosity detection means for detecting the viscosity of the stored waste liquid and heating means for heating the stored waste liquid. <1> This is a device for dispensing the liquid described above. <7> The system comprises means for detecting deterioration of the waste liquid stored in the fixed waste liquid tank, a replacement waste liquid tank, and a valve for switching the destination of the waste liquid supplied from the fixed waste liquid tank between the replacement waste liquid tank and the liquid discharge head, wherein the liquid in which deterioration has been detected is supplied to the replacement waste liquid tank. <1> from <6> This is a device for dispensing any of the liquids described in the following. <8> The fixed waste liquid tank is characterized by having a removable waste liquid storage cartridge for storing the waste liquid to be reused, located downstream of the outlet of the fixed waste liquid tank. <1> from <7> This is a device for dispensing any of the liquids described in the following. <9> The fixed waste liquid tank is provided with a removable waste liquid storage cartridge for storing the waste liquid between the outlet of the fixed waste liquid tank and the liquid discharge head to which the waste liquid is supplied, and further comprises means for detecting the deterioration of the waste liquid stored in the fixed waste liquid tank, a replacement waste liquid tank, and a valve for switching the destination of the waste liquid supplied from the fixed waste liquid tank between the replacement waste liquid tank and the liquid discharge head, and the liquid in which deterioration has been detected is supplied to the replacement waste liquid tank. <6> This is a device for dispensing the liquid described above. [Explanation of symbols]

[0052] 6. Suction pump 7 filters 8 Fixed waste liquid tank 8a Slope 8b Outlet 9. Supply pump 10 Maintenance Department 11 Liquid dispensing head 14 Suction cap 20 liquid cartridges 30 waste liquid storage cartridges 31 Replacement waste liquid tank 32. Waste liquid suction pump 33 Diverter Valve 81 Stirring means 82 Heating means 83 Detection means 100 Liquid dispensing device [Prior art documents] [Patent Documents]

[0053] [Patent Document 1] Japanese Patent Publication No. 2006-305902

Claims

1. A liquid dispensing head that dispenses at least a black liquid, A liquid cartridge that supplies liquid to the liquid dispensing head, A maintenance unit for performing maintenance on the liquid dispensing head, A single fixed wastewater tank for storing wastewater discharged from the aforementioned maintenance unit, The system includes a path for supplying the waste liquid stored in the fixed waste liquid tank to the liquid discharge head that discharges a black liquid, The fixed wastewater tank is equipped with means for agitating the stored wastewater, and has a longitudinal direction on one side and a short direction on the other side, with an inlet provided above one side in the longitudinal direction for the wastewater to flow in longitudinally, and an outlet provided below the other side in the longitudinal direction for the wastewater to be discharged longitudinally. A liquid discharge device characterized in that the interior of the fixed waste liquid tank has a first gradient that decreases from the inlet side to the outlet side in the longitudinal direction, a second gradient that decreases from one outside to the inside in the short direction when the outlet side is considered the inside, and a third gradient that decreases from the other outside to the inside.

2. The liquid discharge device according to Claim 1, characterized in that air is collected above the outlet inside the fixed waste liquid tank.

3. The liquid dispensing apparatus according to claim 1, further comprising viscosity detection means for detecting the viscosity of the waste liquid stored in the fixed waste liquid tank.

4. The liquid dispensing apparatus according to claim 1, further comprising a heating means for heating the waste liquid stored in the fixed waste liquid tank.

5. The liquid dispensing device according to claim 1, characterized in that a filter member for filtering the waste liquid discharged from the maintenance unit is provided on the upstream side of the fixed waste liquid tank.

6. A filter member for filtering the waste liquid discharged from the maintenance unit is provided on the upstream side of the fixed waste liquid tank. The liquid dispensing apparatus according to claim 1, characterized in that the fixed waste liquid tank comprises viscosity detection means for detecting the viscosity of the stored waste liquid and heating means for heating the stored waste liquid.

7. The liquid dispensing apparatus according to claim 1, comprising means for detecting deterioration of the waste liquid stored in the fixed waste liquid tank, a replacement waste liquid tank, and a valve for switching the destination of the waste liquid supplied from the fixed waste liquid tank between the replacement waste liquid tank and the liquid dispensing head, wherein the liquid in which deterioration has been detected is supplied to the replacement waste liquid tank.

8. The liquid dispensing device according to claim 1, further characterized in that it is provided with a removable waste liquid storage cartridge for storing the waste liquid to be reused, located downstream of the outlet of the fixed waste liquid tank.

9. The liquid dispensing device according to claim 6, further comprising a removable waste liquid storage cartridge for storing the waste liquid between the outlet of the fixed waste liquid tank and the liquid dispensing head to which the waste liquid is supplied, means for detecting deterioration of the waste liquid stored in the fixed waste liquid tank, a replacement waste liquid tank, and a valve for switching the destination of the waste liquid supplied from the fixed waste liquid tank between the replacement waste liquid tank and the liquid dispensing head, wherein the liquid in which deterioration has been detected is supplied to the replacement waste liquid tank.

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