JP7013972B2 - Device that discharges liquid - Google Patents

Description

The present invention relates to a device for discharging a liquid.

In recent years, an image forming apparatus using inkjet technology has also been used for printing on product packages (commercial printing). Further, there is a demand for the image forming apparatus to increase the image forming speed and improve the quality of the image forming result. In order to cope with the increase in the image formation speed, the number of nozzles of the liquid discharge head that discharges the liquid used for image formation toward the recording medium is increasing. On the other hand, as the number of nozzles of the liquid discharge head increases, the probability that a liquid discharge failure occurs tends to increase. When ejection defects occur, the quality of the image formation result is deteriorated. Therefore, in order to achieve both high image formation speed and high quality image formation result in the image forming apparatus, some ingenuity is required.

There are multiple causes for poor liquid discharge. One of them is that gas is mixed in at the stage of supplying the liquid to be discharged from the nozzle to the nozzle. If a gas is mixed in the liquid, bubbles may flow together with the liquid into the liquid chamber for discharging the liquid from the nozzle. When the bubbles enter the liquid chamber, the discharge energy (droplet discharge pressure) applied to the liquid chamber is absorbed by the bubbles, and the drop discharge pressure adjusted for forming the optimum droplets cannot be obtained. That is, if the ejection energy is reduced due to the mixing of bubbles, the original ejection state of the droplets cannot be obtained, and the quality of image formation is deteriorated. Further, when a gas enters the liquid supply path from a cartridge or the like that holds the liquid supplied to the liquid discharge head and becomes large bubbles and flows together with the liquid, the liquid supply to the discharge head is roughly damaged and a large number of nozzles are used. It can also be a factor of ejection failure in.

As a technique for preventing a liquid discharge failure from the liquid discharge head due to gas mixing as described above, a circulation path for circulating the liquid supplied to the head is provided, and the liquid tank in the middle of the circulation path is degassed. A technique for providing a degassing circulation flow path provided with an apparatus is disclosed (see, for example, Patent Document 1).

Even if the technique disclosed in Patent Document 1 is used, there is a problem that gas may remain in the liquid circulating in the circulation path, and it is possible to surely prevent a problem that occurs when the head enters the liquid chamber. Further, when the number of bubbles increases, there is a problem that the bubbles overflow from the open portion to the atmosphere provided in a part of the circulation path, which leads to the occurrence of liquid leakage.

An object of the present invention is to provide a device for discharging a liquid while circulating the liquid, which can prevent liquid leakage from an open portion to the atmosphere.

The present invention relates to a device for discharging a liquid, and one aspect thereof is a device for discharging a liquid including a liquid discharge head, the liquid circulation mechanism including the liquid discharge head for circulating the liquid. The liquid circulation mechanism includes a first liquid feed pump for pressurization, a second liquid feed pump for depressurization, and a second liquid feed pump for generating a differential pressure for circulating the liquid to the liquid discharge head. The intermediate tank is arranged between the first liquid feed pumps and connected to the second liquid feed pump and the first liquid feed pump via a fluid path, and the intermediate tank flows in from the second liquid feed pump. It is provided with a gas-liquid separation section that separates the gas mixed in the liquid from the liquid, and the gas-liquid separation section is a liquid that is discharged from the end of the fluid path from the second liquid feed pump and flows in. Includes a gas-liquid separation circulation path including a circulation pump that collects and returns to the intermediate tank via the gas-liquid separation member, the flow rate by the circulation pump is larger than the flow rate by the second liquid feed pump, and the gas-liquid separation The circulation path has a first circulation path in which one end is arranged in the liquid layer of the intermediate tank and the other end is connected to the circulation pump or the gas-liquid separation member, and one end is in the middle. A second circulation path located in the gas layer of the tank, the other end of which is connected to the gas-liquid separation member or the circulation pump, and the end disposed in the gas layer is the second feed. It is characterized in that it is located near the end of the fluid path from the liquid pump .

According to the present invention, in a device that discharges a liquid while circulating the liquid, it is possible to prevent liquid leakage from an open portion to the atmosphere.

The schematic explanatory view of the printing apparatus which is embodiment of the apparatus which ejects a liquid which concerns on this invention. The plan view which shows an example of the head unit which concerns on this embodiment. The external perspective explanatory view which shows an example of the liquid discharge head which concerns on this embodiment. The cross-sectional explanatory view in the liquid chamber longitudinal direction of the liquid discharge head which concerns on this embodiment. The piping explanatory view of the liquid circulation mechanism provided in the apparatus which discharges a liquid which concerns on this embodiment. An explanatory diagram illustrating a state in which liquid leakage occurs in a conventional liquid circulation mechanism. The functional block diagram of the control part of the apparatus which discharges a liquid which concerns on this embodiment. Explanatory drawing explaining the first structural example of the liquid circulation mechanism which concerns on this embodiment. Explanatory drawing explaining the second structural example of the liquid circulation mechanism which concerns on this embodiment. An explanatory diagram illustrating a third configuration example of the liquid circulation mechanism according to the present embodiment.

Hereinafter, an embodiment of a device for discharging a liquid (liquid discharge device) according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a printing apparatus 1000 which is an embodiment of the apparatus according to the present invention.

<Configuration of printing device 1000>
As shown in FIG. 1, the printing apparatus 1000 has a carry-in means 1 for carrying in a continuum 10 in which a recording medium is wound in a roll shape, and a printing means 5 for forming an image on the continuum 10 carried in from the carry-in means 1. The guide transport means 3 for guiding and transporting the continuous body 10, the printing means 5 for printing to form an image by ejecting a liquid to the continuous body 10, the drying means 7 for drying the continuous body 10, and the continuous body 10 are discharged. It is equipped with a discharge means 9 and the like.

The continuum 10 is sent out from the original winding roller 11 installed in the carry-in means 1, guided and conveyed by the rollers of the carry-in means 1, the guide transport means 3, the drying means 7, and the discharge means 9, and is conveyed by the discharge means 9. It is wound up by the take-up roller 91 provided in the above.

The continuum 10 is conveyed on the transfer guide member 59 in the printing means 5 facing the head unit 50 and the post-processing head unit 55, and an image is formed by the liquid discharged from the head unit 50, and the post-processing head is formed. Post-treatment is performed with the treatment liquid discharged from the unit 55.

<Head unit 50>
FIG. 2 is a plan explanatory view of the head unit 50 of the printing apparatus. The head unit 50 is, for example, a full-line head array 51K, 51C, 51M, 51Y for four colors from the upstream side in the medium transport direction (hereinafter, referred to as “head array 51” when the colors are not distinguished). Is placed.

The head array 51 has a plurality of liquid discharge heads 100 (hereinafter, also simply referred to as simply referred to as liquid discharge heads 100) arranged in a staggered manner on the base member 52. The arrangement of the liquid discharge head 100 is not limited to that illustrated in FIG.

Each head array 51 is a liquid discharging means, and each discharges a liquid of black K, cyan C, magenta M, and yellow Y to the conveyed continuum 10. The types and numbers of colors are not limited to this.

<Liquid discharge head 100>
Next, the liquid discharge head 100 according to the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is an external perspective explanatory view of the liquid discharge head 100, and FIG. 4 is a cross-sectional explanatory view in a direction orthogonal to the nozzle arrangement direction (liquid chamber longitudinal direction) of the liquid discharge head 100.

As shown in FIG. 3, the liquid discharge head 100 also serves as a nozzle plate 101, a flow path member 140 laminated on the nozzle plate 101, and a frame member of the liquid discharge head 100 laminated on the flow path member 140. It has a common liquid chamber member 120 and a rectangular parallelepiped cover 129 that covers the upper part of the common liquid chamber member 120. Further, the common liquid chamber member 120 forms a supply side common liquid chamber 110 and a discharge side common liquid chamber 150, which will be described later. The upper surface of the common liquid chamber member 120 has a supply port 171 that leads to the common liquid chamber 110 on the supply side and a discharge port 181 that leads to the common liquid chamber 150 on the discharge side.

Subsequently, the internal structure of the liquid discharge head 100 will be described with reference to FIG. The liquid discharge head 100 has a multi-layer structure in which a nozzle plate 101, a flow path plate 102, and a diaphragm member 103 as a wall surface member are laminated and joined. Further, it includes a piezoelectric actuator 111 that displaces the vibration region 130 of the diaphragm member 103, and a common liquid chamber member 120 that also serves as a frame member of the head. The portion composed of the flow path plate 102 and the diaphragm member 103 corresponds to the flow path member 140.

The nozzle plate 101 has a plurality of nozzles 104, which are discharge ports for discharging liquid.

The flow path plate 102 penetrates into the individual liquid chamber 106 that leads to the nozzle 104 via the nozzle communication passage 105, the supply-side fluid resistance portion 107 that leads to the individual liquid chamber 106, and the liquid introduction portion 108 that leads to the supply-side fluid resistance portion 107. It forms holes and grooves. The nozzle communication passage 105 is a flow path that connects to the nozzle 104 and the individual liquid chamber 106, respectively. Further, the liquid introduction portion 108 is connected to the common liquid chamber 110 on the supply side through the opening 109 of the diaphragm member 103.

The diaphragm member 103 has a deformable vibration region 130 that forms the wall surface of the individual liquid chamber 106 of the flow path plate 102. Here, the diaphragm member 103 has a two-layer structure (not limited), and is formed by a first layer that forms a thin wall portion from the flow path plate 102 side and a second layer that forms a thick wall portion. A deformable vibration region 130 is formed in a portion corresponding to the individual liquid chamber 106.

Then, on the side of the diaphragm member 103 opposite to the individual liquid chamber 106, a piezoelectric actuator 111 including an electromechanical conversion element as a driving means (actuator means, pressure generating means) for deforming the vibration region 130 of the diaphragm member 103 is included. Is placed.

In this piezoelectric actuator 111, a piezoelectric member joined on a base member 113 is grooved by half-cut dicing, and a required number of columnar piezoelectric elements 112 are formed in a comb-teeth shape at predetermined intervals.

Then, the piezoelectric element 112 is joined to the convex portion 130a, which is an island-shaped thick portion formed in the vibration region 130 of the diaphragm member 103. Further, a flexible wiring member 115 is connected to the piezoelectric element 112.

The common liquid chamber member 120 forms a common liquid chamber 110 on the supply side and a common liquid chamber 150 on the discharge side. As described above, the supply-side common liquid chamber 110 leads to the supply port 171 shown in FIG. 3, and the discharge-side common liquid chamber 150 leads to the discharge port 181.

Here, the common liquid chamber member 120 is composed of a first common liquid chamber member 121 and a second common liquid chamber member 122, and the first common liquid chamber member 121 is placed on the diaphragm member 103 side of the flow path member 140. The second common liquid chamber member 122 is laminated and joined to the first common liquid chamber member 121.

The first common liquid chamber member 121 forms a downstream common liquid chamber 110A which is a part of the supply side common liquid chamber 110 leading to the liquid introduction portion 108 and a discharge side common liquid chamber 150 leading to the discharge flow path 151. ing. Further, the second common liquid chamber member 122 forms the upstream common liquid chamber 110B, which is the remainder of the supply side common liquid chamber 110.

Further, the flow path plate 102 is formed with a discharge flow path 151 along the surface direction of the flow path plate 102 that communicates with each individual liquid chamber 106 via the nozzle communication passage 105. The discharge flow path 151 leads to the discharge side common liquid chamber 150.

In the liquid discharge head 100, for example, the piezoelectric element 112 contracts by lowering the voltage applied to the piezoelectric element 112 from the reference potential (intermediate potential). Due to this contraction, the vibration region 130 of the diaphragm member 103 is pulled and the volume of the individual liquid chamber 106 expands. By such an operation, the liquid flows into the individual liquid chamber 106. After that, when the voltage applied to the piezoelectric element 112 is increased to extend the piezoelectric element 112 in the stacking direction, the diaphragm member 103 deforms the vibration region 130 in the direction toward the nozzle 104 and contracts the volume of the individual liquid chamber 106. .. By such an operation, the liquid in the individual liquid chamber 106 is pressurized, and the liquid is discharged from the nozzle 104.

Further, the liquid that is not discharged from the nozzle 104 passes through the nozzle 104 and is discharged from the discharge flow path 151 to the discharge side common liquid chamber 150, and is discharged from the discharge side common liquid chamber 150 through the liquid circulation mechanism 200 described later to the supply side common liquid chamber. It is supplied to 110 again.

The driving method of the liquid discharge head 100 is not limited to the above example (pull-pushing), and pulling or pushing may be performed depending on the driving waveform.

<Liquid circulation path>
Next, an embodiment of the liquid circulation path provided in the device for discharging the liquid according to the present invention will be described with reference to FIG. FIG. 5 is a piping explanatory view showing a basic configuration of the liquid circulation mechanism 200 according to the present embodiment.

The liquid circulation mechanism 200 shown in FIG. 5 exemplifies a configuration for circulating liquid in a line head type in which a plurality of liquid discharge heads 100 having a configuration capable of circulating liquid are arranged in a line in the width direction of the continuum 10. is doing.

The liquid circulation mechanism 200 includes a main tank 201 (liquid tank) which is a liquid supply means for supplying the liquid discharged from the liquid discharge head 100 to the circulation path. Further, it is provided with a pressurizing side tank 220 (first sub-tank), a depressurizing side tank 210 (second sub-tank), and a buffer tank 290 (intermediate tank) constituting a structure for generating a differential pressure for circulating a liquid. .. The decompression side tank 210, the pressurization side tank 220, and the buffer tank 290 are connected by each circulation path, and have a configuration in which a liquid flows with respect to each. The configuration for flowing this liquid includes a pressurizing liquid feed pump 202 (first liquid feed pump) which is a pressurizing side pump, a depressurizing liquid feeding pump 203 (second liquid feeding pump) which is a depressurizing side pump, and the like. A supply pump 209 (third liquid feed pump) for supplying liquid to the circulation path is included.

Further, the liquid circulation mechanism 200 includes a supply-side head tank 300a (first), which is arranged in each of the liquid supply-side paths of the first manifold 230, the second manifold 240, and the liquid discharge head 100, which communicate with the plurality of liquid discharge heads 100. (1 head tank), the discharge side head tank 300b (second head tank) arranged in each liquid discharge side path of the liquid discharge head 100, and degassing means for removing the dissolved gas in the liquid. It is equipped with a gas device 260. In the following description, when the liquid supply side and the liquid discharge side are not distinguished, it is referred to as "head tank 300".

Further, the buffer tank 290 is arranged between the pressurizing side tank 220 and the depressurizing side tank 210, and is fed from the main tank 201 by the supply pump 209 via the fluid path 289 including the main filter 205. The buffer tank 290 is provided with a buffer liquid level sensor 291 and a buffer air release valve 292 that constitutes an air release mechanism that opens the inside of the buffer tank 290 to the atmosphere.

The buffer tank 290 and the decompression side tank 210 are connected to each other through a fluid path 283, and a decompression liquid feed pump 203 is arranged in the fluid path 283. The decompression side tank 210 has a gas chamber 210a, and is configured such that a liquid and a gas coexist. The decompression side tank 210 is provided with a decompression side liquid level sensor 211 for detecting the liquid level and a decompression side atmosphere release valve 212 which is an electromagnetic valve for opening the inside to the atmosphere.

The buffer tank 290 and the pressurizing side tank 220 are connected to each other through a fluid path 284, and a pressurizing liquid feed pump 202 is arranged in the fluid path 284.

The pressurizing side tank 220 has a gas chamber 220a, and is configured such that a liquid and a gas coexist. The pressurizing side tank 220 is provided with a pressurizing side liquid level sensor 221 for detecting the liquid level and a pressurizing side atmospheric opening valve 222 as an atmospheric opening mechanism for opening the inside to the atmosphere. The pressurizing side tank 220 is connected to the first manifold 230 through a fluid path 281 including a degassing device 260 and a circulation filter 261.

The first manifold 230 is connected to the supply port 171 (supply port) side of the liquid discharge head 100 via the supply path 231. The supply path 231 is connected to the supply port 171 of the liquid discharge head 100 via the supply side head tank 300a. The supply path 231 is provided with a solenoid valve 232 that opens and closes the path upstream of the supply side head tank 300a. The solenoid valve 232 is provided according to the number of liquid discharge heads 100, and can be individually opened and closed. Further, the first manifold 230 is provided with a first pressure sensor 233.

The decompression side tank 210 is connected to the second manifold 240 via the fluid path 282. The second manifold 240 is connected to the discharge port 181 (discharge port) side of the liquid discharge head 100 via the discharge path 241. The discharge path 241 is connected to the discharge port 181 of the liquid discharge head 100 via the discharge side head tank 300b. The discharge path 241 is provided with a solenoid valve 242 that opens and closes the path downstream of the discharge side head tank 300b. The solenoid valve 242 is provided according to the number of liquid discharge heads 100, and can be individually opened and closed. Further, the second manifold 240 is provided with a second pressure sensor 243.

Further, a bypass path 270 is provided through the first manifold 230 and the second manifold 240. The bypass path 270 is provided with a solenoid valve 271 on the first manifold 230 side and a solenoid valve 272 on the second manifold 240 side.

A path from the buffer tank 290 to the buffer tank 290 via the fluid path 284, the pressurizing side tank 220, the fluid path 281, the deaerator 260, the first manifold 230, the bypass path 270, the second manifold 240, and the decompression side tank 210. The first route is used. The first path is a path in which the liquid discharge head 100 does not become a part of the circulation path and the bypass path 270 becomes a part of the circulation path.

A path from the buffer tank 290 to the buffer tank 290 via the fluid path 284, the pressurizing side tank 220, the fluid path 281, the deaerator 260, the first manifold 230, the liquid discharge head 100, the second manifold 240, and the decompression side tank 210. Is the second route. The second path is a path in which the liquid discharge head 100 is a part of the circulation path and the bypass path 270 is not a part of the circulation path.

By controlling the opening and closing of the solenoid valve 232, the solenoid valve 242, the solenoid valve 271, and the solenoid valve 272, the configuration of the circulation path can be switched. Each of these solenoid valves constitutes a switching means.

Further, a means for generating a pressure for circulating the liquid supplied from the main tank 201 in the circulation path is configured by the pressurizing side tank 220 and the depressurizing side tank 210, the pressurizing liquid feeding pump 202 and the depressurizing liquid feeding pump 203. There is.

<1: Replenishment of buffer tank 290>
Next, the supply and circulation of the liquid will be described. First, the liquid transfer from the main tank 201 to the buffer tank 290 will be described. When the buffer liquid level sensor 291 for detecting the amount of liquid stored in the buffer tank 290 detects that the amount of liquid is insufficient, the supply pump 209 is used from the main tank 201 to the buffer tank 290 via the fluid path 289. The liquid is supplied. This supply operation continues until the buffer liquid level sensor 291 detects the liquid level.

<2: Liquid transfer from the buffer tank 290 to the pressurized tank 220>
Using the pressurizing liquid feed pump 202, the liquid is fed from the buffer tank 290 to the pressurizing side tank 220 via the fluid path 284.

<3: Liquid transfer from the decompression side tank 210 to the buffer tank 290>
Using the decompression liquid feed pump 203, the liquid is supplied from the decompression side tank 210 to the buffer tank 290 via the fluid path 283.

<4: Liquid transfer by the second route>
Ink is supplied to the pressurizing side tank 220 by using the pressurizing liquid feed pump 202 until the first pressure sensor 233 reaches the target pressure (for example, the pressure to be pressurized). At the same time, the liquid is supplied to the buffer tank 290 using the depressurizing liquid feed pump 203 until the second pressure sensor 243 reaches the target pressure (for example, a pressure that becomes a negative pressure). By doing these, a differential pressure is generated between the pressurizing side tank 220 and the depressurizing side tank 210. In response to this differential pressure, from the pressurizing side tank 220 via the fluid path 281, a circulation filter 261, a degassing device 260, a first manifold 230, a plurality of supply paths 231 and a plurality of supply side head tanks 300a, a plurality of Liquid can be circulated to the decompression side tank 210 via the liquid discharge head 100, the plurality of discharge paths 241 and the plurality of discharge side head tanks 300b, the second manifold 240, and the fluid path 282. At this time, the solenoid valve 232 and the solenoid valve 242 are open, and the solenoid valves 271 and the solenoid valve 272 are closed.

<5: Liquid delivery by the first route>
With the solenoid valve 232 and the solenoid valve 242 closed and the solenoid valve 271 and the solenoid valve 272 open, the pressurizing liquid feed pump 202 and the depressurizing liquid feed pump 203 are driven to generate a differential pressure. In response to this differential pressure, the liquid flows from the buffer tank 290 through the fluid path 284. Further, from the pressurizing side tank 220 to the depressurizing side tank 210 via the fluid path 281 in the order of the circulation filter 261, the deaerator 260, the first manifold 230, the bypass path 270, the second manifold 240, and the fluid path 282. The liquid circulates. Then, by the operation of the decompression liquid feed pump 203, the liquid flows from the decompression side tank 210 to the buffer tank 290 via the fluid path 283. The liquid circulates as described above.

The decompression side liquid level sensor 211 for detecting the liquid level of the decompression side tank 210, the pressurization side liquid level sensor 221 for detecting the liquid level of the pressurization side tank 220, and the buffer liquid level sensor for detecting the liquid level of the buffer tank 290. The format of 291 is not limited to any of the above. For example, it is possible to use a float method for detecting the presence or absence of a liquid, a method for detecting the presence or absence of a liquid according to the output of a voltage detected by using at least two or more electrode pins, a liquid level detection method using a laser, and the like. can.

Further, the decompression side tank 210, the buffer tank 290, and the pressurization side tank 220 are provided with a decompression side atmosphere opening valve 212, a buffer atmosphere opening valve 292, and a pressurizing side atmosphere opening valve 222, which are solenoid valves as an atmosphere opening mechanism, respectively. ing. By controlling the opening and closing of these tanks, it is possible to communicate with the atmosphere.

The liquid level of the buffer tank 290 is arranged below the nozzle surface of the liquid discharge head 100 by a predetermined distance in the direction of gravity. As a result, when the buffer atmosphere release valve 292 of the buffer tank 290 is opened, the head difference corresponding to the height difference is constantly stably applied to the liquid discharge head 100. Therefore, when the liquid circulation is stopped or the like, the meniscus of the nozzle included in the liquid discharge head 100 can be stably maintained due to the head difference. Further, since the pressure of the buffer tank 290 becomes constant, it becomes easy to control the pressures of the pressurizing side tank 220 and the depressurizing side tank 210 even during liquid circulation during liquid discharge, and the liquid discharge characteristics can be further stabilized.

Further, the liquid circulation mechanism 200 includes a gas-liquid separation unit 400 which is a circulation path for separating the gas mixed in the liquid to be circulated in the buffer tank 290. The detailed configuration of the gas-liquid separation unit 400 will be described later, and will be described first. A comparative example for explaining the effect obtained by providing the gas-liquid separation unit 400 will be described with reference to FIG. FIG. 6 illustrates the configuration of the buffer tank 290 when the gas-liquid separation unit 400 is not provided. As described above, when the liquid circulates in the buffer tank 290, the liquid enters from the depressurizing liquid feed pump 203 and exits to the pressurizing liquid feed pump 202 by the pressurizing liquid feed pump 202.

If gas is mixed from the nozzle opening or piping of the liquid circulation mechanism 200 during the initial filling of the liquid for the first time or during the time when the liquid discharge head 100 is operated to perform the liquid discharge process, a buffer is supplied from the depressurizing liquid feed pump 203. Gas is mixed with the liquid flowing in the tank 290. As a result, as shown in FIG. 6, the mixed gas 601a is discharged to the liquid layer 290b in the buffer tank 290. The mixed gas 601a becomes bubbles 601b in the gas layer 290a in the buffer tank 290. When the amount of the mixed gas 601a is large, as shown in FIG. 6, a large number of bubbles 601b are generated in the gas layer 290a of the buffer tank 290.

As described above, the buffer tank 290 is provided with a buffer air release valve 292. Therefore, when the amount of bubbles 601b generated in the gas layer 290a increases, the bubbles 601b overflow from the buffer atmosphere opening valve 292. That is, when the amount of the mixed gas 601a increases, liquid leakage occurs from the buffer atmosphere release valve 292. The liquid circulation mechanism 200 according to the present embodiment includes a gas-liquid separation unit 400 in order to prevent the above-mentioned problems.

<Control unit 500>
Here, the functional block of the control function for controlling the operation of the device for discharging the liquid will be described with reference to FIG. 7. As shown in FIG. 7, the control unit 500 is a ROM (Read Only Memory) that stores fixed data such as a CPU (Central Processing Unit) 501 that controls the entire printing device 1000 and various programs including a program executed by the CPU 501. It includes a main control unit 500A composed of a 502 and a RAM (Random Access Memory) 503 for temporarily storing image data and the like.

The control unit 500 includes a rewritable non-volatile memory 504 (NVRAM: Non-Volunteer Random Access Memory) for holding data even when the power is cut off. The control unit 500 includes an ASIC (Applicatin Specific Integrated Circuit) 505 that processes various signal processing for image data, image processing for sorting, and other input / output signals for control, and a host I / F (Interface). ) Send and receive data to and from the printer driver 590 via 506.

The control unit 500 includes a print control unit 508 and a head driver 509. The print control unit 508 includes a data transfer means, a drive signal generation means, and a bias voltage output means for driving and controlling each of the liquid discharge heads 100 included in the head unit 50. The head driver 509 is a drive IC for driving each liquid discharge head 100.

The control unit 500 includes a solenoid valve control unit 510 that drives and controls each solenoid valve (232, 242, 271, 272, 212, 222, 292) that constitutes the solenoid valve group 550.

The control unit 500 includes a supply system control unit 511 that drives and controls the supply pump 209.

The control unit 500 includes a pressurizing liquid feed pump 202 and a pressure system control unit 512 that drives and controls the depressurizing liquid feed pump 203 to generate and adjust the differential pressure.

The control unit 500 drives and controls the first pump 401, the second pump 411, the first exhaust pump 406 and the like constituting the liquid circulation mechanism 200 described later, and degass to control the operation of removing the mixed gas 601a. It includes a system control unit 516.

The control unit 500 has an I / O unit 513. The I / O unit 513 can process various sensor information, and acquires the detection results of the first pressure sensor 233 and the second pressure sensor 243 and the information from various sensor groups 515. Then, the information necessary for controlling the printing device 1000 is extracted and used for control by the printing control unit 508, the solenoid valve control unit 510, the supply system control unit 511, the pressure system control unit 512, the degassing system control unit 516, and the like. ..

An operation panel 514 for inputting and displaying information necessary for this device is connected to the control unit 500.

Next, an embodiment of the device for discharging the liquid according to the present invention will be described. The following embodiments are only for the characteristic configuration provided in the device for discharging the liquid, and the details such as the liquid discharge operation and the liquid circulation operation in the device for discharging the liquid will be omitted.

[First Embodiment]
FIG. 8 is an example of a gas-liquid separation structure provided in the liquid circulation mechanism 200 included in the printing apparatus 1000. The gas-liquid separation unit 400 according to the present embodiment includes a first pump 401 that is a circulation pump, a filter 402, and an umbrella-shaped member 403 that constitutes a gas retention unit. Further, the gas-liquid separation unit 400 includes a first separation path 404a, a second separation path 404b, and a third separation path 404c that connect the above configurations.

The first separation path 404a is a pipe having one end in the liquid layer 290b and the other end corresponding to the first circulation path connected to the first pump 401. The second separation path 404b is a pipe corresponding to a second circulation path connecting one to the first pump 401 and the other to the filter 402. The third separation path 404c is a pipe having one connected to the filter 402 and the other corresponding to the third circulation path in the gas layer 209a. The gas-liquid separation unit 400 has one end in the liquid layer 290b and the other end in the first circulation path connected to the first pump 401 or the filter 402, and one end in the gas layer 290a. It can also be seen as a configuration including a second circulation path in which the other end is connected to the filter 402 or the first pump 401. In this case, the first circulation path may be such that one end is arranged in the liquid layer 290b and the other end is connected to the filter 402 or the first pump 401, and the second circulation path is in the gas layer 290a. One end may be arranged and the other end may be connected to the first pump 401 or filter 402.

The relationship between the first pump 401 and the filter 402 is not limited to the connection mode as shown in FIG. For example, the first separation path 404a is connected to the filter 402, the second separation path 404b is connected to the opposite side of the filter 402, the first pump 401 is connected downstream thereof, and the gas passes through the third separation path 404c. It may be circulated so as to return to the layer 290c.

The gas-liquid separation unit 400 constitutes a gas-liquid separation circulation path that collects the liquid containing the mixed gas 601a from the liquid layer 290b of the buffer tank 290 and discharges it to the gas layer 290a.

By operating the first pump 401, the liquid is sucked up from the liquid layer 290b through the first separation path 404a and reaches the filter 402 through the second separation path 404b. The liquid and gas are separated in the filter 402, and the liquid returns to the buffer tank 290 via the third separation path 404c. As described above, the liquid stored inside the buffer tank 290 is circulated.

As described above, the liquid is sent to the buffer tank 290 from the depressurizing liquid feed pump 203 via the fluid path 283. Therefore, the position where the liquid in which the gas is mixed in the buffer tank 290 is discharged is the discharge side end of the fluid path 283 inside the buffer tank 290. Therefore, one end of the first separation path 404a is set in the vicinity of the discharge side end of the fluid path 283 and in the liquid layer 290b.

Further, in order to ensure that the gas (mixed gas 601a) discharged from the discharge end of the fluid path 283 is sucked up from one end of the first separation path 404a, as a gas retention portion above the discharge side end. Umbrella-shaped member 403 is arranged. The umbrella-shaped member 403 is a member that prevents the mixed gas 601a discharged from the discharge side end of the fluid path 283 from staying in a part of the liquid layer 290b and diverging from the gas layer 290a. One end of the first separation path 404a is arranged at a position where the mixed gas 601a is collected by the umbrella-shaped member 403.

The filter 402 is a mesh-shaped member, and is a gas-liquid separation member made of a member having a property that a liquid is easy to pass through and a gas is difficult to pass through. When the liquid passes through the filter 402, the liquid advances and the mixed gas 601a lags behind the liquid. As a result, the liquid and the mixed gas 601a are separated, and the gas from which the mixed gas 601a is separated is returned to the buffer tank 290. Further, the mixed gas 601a gathers on the first pump 401 side of the filter 402, and the bubbles may pop and become smaller or disappear due to the flow of the liquid. If this is released to the gas layer 290a, minute bubbles may remain on the surface of the liquid layer 290b, but if it is a minute bubble, it can be prevented from overflowing from the buffer atmosphere release valve 292.

The flow rate of the first pump 401 is set to be larger than the flow rate of the depressurizing liquid feed pump 203. As a result, the mixed gas 601a released into the liquid layer 290b is surely recovered by the gas-liquid separation unit 400.

Further, since the umbrella-shaped member 403 prevents the released mixed gas 601a from moving in the liquid surface direction, the shape does not have to be the umbrella-shaped one as illustrated in FIG. It is desirable to have a tapered shape in which the upper side is narrowed so that the mixed gas 601a gathers in one place.

It is desirable that the gas-liquid separation unit 400 be installed at a position away from the buffer atmosphere release valve 292. In particular, it is more desirable that the third separation path 404c for returning the liquid that has passed through the filter 402 to the liquid layer 290b is farther from the buffer atmosphere release valve 292. Therefore, as illustrated in FIG. 8, the buffer atmosphere release valve 292 and the gas-liquid separation unit 400 may be arranged at both ends in the horizontal direction of the buffer tank 290.

The buffer tank 290 may be provided with an inner wall portion 293 that divides the liquid layer 290b in the vertical direction. The inner wall portion 293 is provided on the side close to the buffer atmosphere opening valve 292, and regulates the direct movement of the mixed gas 601a to the buffer atmosphere opening valve 292 side even if it comes off from the umbrella-shaped member 403. ..

According to the present embodiment described above, in the liquid circulation mechanism 200 that circulates the liquid while generating a differential pressure in order to perform pressure control for defining the discharge characteristics of the liquid discharge head 100, the gas in the circulation path is generated. The gas can be separated from the mixed liquid and returned to the circulation path.

According to the printing apparatus 1000 having the characteristic configuration according to the above embodiment, even if air is mixed in the liquid at the time of initial filling of the liquid or over time, it is possible to reliably prevent the liquid from leaking. Therefore, it is possible to obtain a device that discharges a liquid that is easy to maintain and has resistance to continuous operation for a long time.

[Second Embodiment]
Next, another example of the gas-liquid separation structure provided in the liquid circulation mechanism 200, which is an embodiment of the device for discharging the liquid according to the present invention, will be described. The gas-liquid separation structure shown in FIG. 9 partially includes a configuration common to the gas-liquid separation unit 400 already described. The following description describes the different parts in detail.

The gas-liquid separation unit 400a according to the present embodiment uses a degassing module that removes gas from the liquid instead of the filter 402 that separates the liquid and the gas. As shown in FIG. 9, the gas-liquid separation unit 400a includes a first degassing module 405 and a first exhaust pump 406 forcibly exhausting air from the first degassing module 405 in the piping constituting the separation path.

Further, in the present embodiment, in addition to the gas-liquid separation section 400a constituting the first gas-liquid separation path, the forced exhaust section 410 constituting the second gas-liquid separation path is provided. The forced exhaust unit 410 includes a second degassing module 412 and a second exhaust pump 413 forcibly exhausting air from the second degassing module 412.

The forced exhaust section 410 includes a first exhaust path 414c, a second pump 411 which is a degassing pump, a second exhaust path 414b, a second degassing module 412, a second exhaust pump 413, and a third exhaust path. It has 414a and. Further, the forced exhaust unit 410 includes a second exhaust passage 414d that connects the second degassing module 412 and the second exhaust pump 413.

The forced exhaust unit 410 constitutes a forced exhaust circulation path that recovers the gas containing minute bubbles from the gas layer 290a of the buffer tank 290 and discharges the gas to the gas layer 290a.

Both the first degassing module 405 and the second degassing module 412 are gas-liquid separation members composed of a hollow fiber filter having a property of passing only gas without passing liquid. The first degassing module 405 and the second degassing module 412 are members for removing air contained in the liquid in the path by reducing the pressure in the space outside the path. The space outside the first degassing module 405 is depressurized by the first exhaust pump 406, and the mixed gas 601a is removed through the first exhaust passage 404d. The liquid from which the mixed gas 601a has been removed is returned to the gas layer 290a of the buffer tank 290. This ensures that the mixed gas 601a is removed.

The second degassing module 412 is for circulating and exhausting the gas layer 290a between the gas-liquid separation unit 400a and the buffer atmosphere opening valve 292. Even if bubbles remain in the liquid returned to the buffer tank 290 by the gas-liquid separation unit 400a by the second degassing module 412 and accumulate on the surface of the liquid layer 290b, the bubbles are used by the second pump 411. Can be recovered, separated into gas and liquid, and returned to the buffer tank 290. As a result, it is possible to prevent bubbles from increasing in the gas layer 290a and leaking to the outside from the buffer atmosphere release valve 292.

Further, since the air flows out from the buffer atmosphere opening valve 292 by the amount of the air discharged to the outside by the second degassing module 412 of the forced exhaust unit 410, the air passes through the buffer atmosphere opening valve 292 from the inside of the buffer tank 290. The amount of gas flowing out is reduced. This makes it possible to prevent clogging of the buffer atmosphere release valve 292 side due to bubbles.

The liquid flows into the liquid circulation mechanism 200 when the decompression pump 203 is operating. Therefore, the time when the depressurizing liquid feed pump 203 is operating is the timing at which the mixed gas 601a flows into the buffer tank 290. Therefore, the operations of the first pump 401, the second pump 411, the first exhaust pump 406, and the second exhaust pump 413 may be synchronized with the operations of the depressurizing liquid feed pump 203.

By controlling the operation timing in this way, when the liquid is not flowing (when the mixed gas 601a does not flow into the buffer tank 290), the operations of the plurality of pumps are stopped to prevent wasteful power consumption. can. Further, by such control, the life of the first degassing module 405, the second degassing module 412, the first pump 401, the second pump 411, and the like can be extended.

[Third Embodiment]
Next, another example of the gas-liquid separation structure provided in the liquid circulation mechanism 200, which is an embodiment of the device for discharging the liquid according to the present invention, will be described. The gas-liquid separation structure shown in FIG. 10 is further characterized by a recovery portion of the mixed gas 601a with respect to the configuration of the gas-liquid separation section 400a and the forced exhaust section 410 according to the second embodiment.

In the present embodiment, the growth of air bubbles in the liquid layer 290b of the buffer tank 290 is prevented by the two gas-liquid separation paths of the first gas-liquid separation path and the second gas-liquid separation path as in the configuration of FIG. In addition, it prevents bubbles from flowing into the outside from the buffer atmosphere release valve 292.

In the present embodiment, in the gas-liquid separation unit 400a, the position where the mixed gas 601a is collected is set to the deep position of the buffer tank 290. Therefore, it is assumed that the buffer tank 290 has a larger depth dimension than that of the embodiment described above.

At the deep position (deep part) of the liquid layer 290b, the mixed gas 601a is in a small state due to water pressure. Therefore, by collecting the mixed gas 601a in the gas-liquid separation unit 400a at a small stage, when it is taken into the first separation path 404a, the mixed gas 601a can be removed more reliably.

Further, an inclined plate 403b as a gas retention portion is installed near the end of the first separation path 404a located inside the liquid layer 290b. The inclined plate 403b is an inclined member fixed to a part of the inner wall of the buffer tank 290 so that the lower side thereof is separated from the wall. By arranging the end portion of the fluid path 283 below the inclined plate 403b, the mixed gas 601a is collected on the wall side along the inclined plate 403b. By arranging one end of the first separation path 404a at the aggregation position, the mixed gas 601a can be recovered more reliably.

According to the present embodiment described above, by arranging the opening in the buffer tank 290 of the pipe (fluid path 283) communicating with the depressurizing liquid feed pump 203 at a deep position, the mixed gas 601a can be discharged from the opening. When discharged, the bubbles are taken into the first separation path 404a in a small state due to the action of water pressure in the buffer tank 290. As a result, defoaming and defoaming can be performed more effectively.

<Supplementary information regarding the device that discharges liquid>
In the present application, the "liquid" to be discharged may have a viscosity and surface tension that can be discharged from the head, and is not particularly limited, but has a viscosity of 30 mPa · s or less at room temperature, under normal pressure, or by heating or cooling. Is preferable. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functionalizing materials such as surfactants, biocompatible materials such as DNA, amino acids and proteins, and calcium. , Solvents, suspensions, emulsions, etc. containing edible materials such as natural pigments, such as inks for inkjets, surface treatment liquids, components of electronic and light emitting elements, and formation of electronic circuit resist patterns. It can be used in applications such as liquids and material liquids for three-dimensional modeling.

The "liquid discharge head" includes a piezoelectric actuator (laminated piezoelectric element and thin film type piezoelectric element), a thermal actuator using an electric heat conversion element such as a heat generating resistor, a vibrating plate and a counter electrode as an energy generation source for discharging liquid. Includes those that use electrostatic actuators and the like.

The "device for discharging a liquid" includes a device for driving a liquid discharge head to discharge a liquid. The device for discharging the liquid includes not only a device capable of discharging the liquid to a device to which the liquid can adhere, but also a device for discharging the liquid into the air or into the liquid.

The "device for discharging the liquid" may include means for feeding, transporting, and discharging paper to which the liquid can adhere, as well as a pretreatment device, a posttreatment device, and the like.

For example, as a "device that ejects a liquid", an image forming device that is a device that ejects ink to form an image on paper, and a three-dimensional object (three-dimensional object) are formed in layers in order to form a three-dimensional object. There is a three-dimensional modeling device (three-dimensional modeling device) that discharges the modeling liquid into the powder layer.

Further, the "device for discharging a liquid" is not limited to a device in which a significant image such as characters and figures is visualized by the discharged liquid. For example, those that form patterns that have no meaning in themselves and those that form a three-dimensional image are also included.

The above-mentioned "thing to which a liquid can adhere" means a material to which a liquid can adhere at least temporarily, such as a material to which the liquid adheres and adheres, and a material to which the liquid adheres and permeates. Specific examples include paper, recording paper, recording paper, film, recorded media such as cloth, electronic substrates, electronic components such as piezoelectric elements, powder layers (powder layers), organ models, and media such as inspection cells. Yes, and includes everything to which the liquid adheres, unless otherwise specified.

The material of the above-mentioned "material to which a liquid can adhere" may be paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics or the like as long as the liquid can adhere even temporarily.

Further, the "device for discharging the liquid" includes, but is not limited to, a device in which the liquid discharge head and the device to which the liquid can adhere move relatively. Specific examples include a serial type device that moves the liquid discharge head, a line type device that does not move the liquid discharge head, and the like.

In addition, as a "device for ejecting a liquid", a treatment liquid coating device for ejecting a treatment liquid to the paper in order to apply the treatment liquid to the surface of the paper for the purpose of modifying the surface of the paper, etc. There is an injection granulation device that granulates fine particles of raw materials by injecting a composition liquid in which raw materials are dispersed in a solution through a nozzle.

In addition, in the term of this application, image formation, recording, printing, printing, printing, modeling, etc. are all synonymous.

Although the above-described embodiment is a preferred example of the present invention, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

1: Carry-in means 3: Guide-carrying means 5: Printing means 7: Drying means 9: Discharging means 10: Continuum 11: Original winding roller 50: Head unit 51: Head array 51C: Full-line type Head array 51K: Full-line type Head array 51M: Full line type head array 51Y: Full line type head array 52: Base member 55: Post-processing head unit 59: Conveyance guide member 91: Winding roller 100: Liquid discharge head 101: Nozzle plate 102: Flow path plate 103: Vibrating plate member 104: Nozzle 105: Nozzle communication passage 106: Individual liquid chamber 107: Supply side fluid resistance part 108: Liquid introduction part 109: Opening 110: Supply side common liquid chamber 110A: Downstream side common liquid chamber 110B: Upstream Side common liquid chamber 111: piezoelectric actuator 112: piezoelectric element 113: base member 115: flexible wiring member 120: common liquid chamber member 121: first common liquid chamber member 122: second common liquid chamber member 129: cover 130: vibration region 130a: Convex portion 140: Flow path member 150: Discharge side common liquid chamber 151: Discharge flow path 171: Supply port 181: Discharge port 200: Liquid circulation mechanism 201: Main tank 202: Pressurizing liquid feed pump 203: Depressurizing feed Liquid pump 205: Main filter 209: Supply pump 209a: Gas layer 210: Decompression side tank 210a: Gas chamber 211: Decompression side liquid level sensor 212: Decompression side atmosphere release valve 220: Pressurization side tank 220a: Gas chamber 221: Pressurization side Liquid level sensor 222: Pressurized side atmospheric release valve 230: First manifold 231: Supply path 232: Electromagnetic valve 233: First pressure sensor 240: Second manifold 241: Discharge path 242: Electromagnetic valve 243: Second pressure sensor 260: Degassing device 261: Circulation filter 270: Bypass path 271: Electromagnetic valve 272: Electromagnetic valve 281: Fluid path 282: Fluid path 283: Liquid path 284: Fluid path 289: Fluid path 290: Buffer tank 290a: Gas layer 290b: Liquid layer 290c: Gas layer 291: Liquid level sensor for buffer 292: Buffer atmosphere release valve 293: Inner wall part 300: Head tank 300a: Supply side head tank 300b: Discharge side head tank 400: Gas / liquid separation part 400a: Gas / liquid separation part Part 401: First pump 402: Filter 403: Umbrella-shaped member 403b : Inclined plate 404a: First separation path 404b: Second separation path 404c: Third separation path 404d: First exhaust path 405: First degassing module 406: First exhaust pump 410: Forced exhaust section 411: Second pump 412: Second degassing module 413: Second exhaust pump 414a: Third exhaust path 414b: Second exhaust path 414c: First exhaust path 414d: Second exhaust path 500: Control unit 500A: Main control unit 501: CPU
504: Non-volatile memory 508: Print control unit 509: Head driver 510: Solenoid valve control unit 511: Supply system control unit 512: Pressure system control unit 513: I / O unit 514: Operation panel 515: Sensor group 516: Degassing System control unit 550: Solenoid valve group 590: Printer driver 601a: Mixed gas 601b: Bubbles 1000: Printing device

Japanese Unexamined Patent Publication No. 2009-279848

Claims (10)

A device that discharges a liquid equipped with a liquid discharge head.
A liquid circulation mechanism including the liquid discharge head and circulating the liquid is provided.
The liquid circulation mechanism is
Between the first liquid feed pump for pressurization and the second liquid feed pump for decompression, and the second liquid feed pump and the first liquid feed pump for generating a differential pressure for circulating the liquid to the liquid discharge head. Includes an intermediate tank located in and connected to the second and first liquid feed pumps via the fluid path.
The intermediate tank includes a gas-liquid separation unit that separates the gas mixed in the liquid flowing from the second liquid feeding pump from the liquid.
The gas-liquid separation unit includes a gas-liquid separation circulation including a circulation pump that collects the liquid discharged from the end of the fluid path from the second liquid feed pump and returns it to the intermediate tank via the gas-liquid separation member. Including the path, the flow rate by the circulation pump is larger than the flow rate by the second liquid feed pump.
The gas-liquid separation circulation route is
A first circulation path in which one end is located in the liquid layer of the intermediate tank and the other end is connected to the circulation pump or the gas-liquid separation member.
One end is disposed in the gas layer of the intermediate tank and the other end comprises a gas-liquid separation member or a second circulation path connected to the circulation pump.
The end arranged in the gas layer is arranged in the vicinity of the end of the fluid path from the second liquid feed pump.
A device that discharges a liquid. The device for discharging a liquid according to claim 1 , wherein a gas retention portion is installed in the vicinity of one end of the first circulation path. The device for discharging a liquid according to claim 2, wherein the gas retention portion is composed of a tapered member that narrows upward. The device for discharging a liquid according to claim 2, wherein the gas retention portion comprises an inclined member that inclines upward. A device that discharges a liquid equipped with a liquid discharge head.
A liquid circulation mechanism including the liquid discharge head and circulating the liquid is provided.
The liquid circulation mechanism is
Between the first liquid feed pump for pressurization and the second liquid feed pump for decompression, and the second liquid feed pump and the first liquid feed pump for generating a differential pressure for circulating the liquid to the liquid discharge head. Includes an intermediate tank located in and connected to the second and first liquid feed pumps via the fluid path.
The intermediate tank includes a gas-liquid separation unit that separates the gas mixed in the liquid flowing from the second liquid feeding pump from the liquid.
The gas-liquid separation unit includes a gas-liquid separation circulation including a circulation pump that collects the liquid discharged from the end of the fluid path from the second liquid feed pump and returns it to the intermediate tank via the gas-liquid separation member. Including the route,
The flow rate by the circulation pump is larger than the flow rate by the second liquid feed pump.
The gas-liquid separation unit includes a forced exhaust circulation path including a degassing pump that recovers gas from the gas layer of the intermediate tank and returns it to the gas layer via a gas-liquid separation member.
The forced exhaust circulation route is
A first exhaust path in which one end is placed in the gas of the intermediate tank and the other end is connected to the degassing pump.
A second exhaust path, one end of which is connected to the degassing pump and the other end of which is connected to the gas-liquid separation member.
One end is connected to the gas-liquid separation member, and the other end is a third exhaust path arranged in the gas layer of the intermediate tank.
Includes an exhaust passage having one end connected to the gas-liquid separation member and the other end connected to an exhaust pump.
A device that discharges a liquid. The device for discharging a liquid according to claim 5 , wherein the exhaust pump and the circulation pump operate in synchronization with the operation of the second liquid feed pump. A device that discharges a liquid equipped with a liquid discharge head.
A liquid circulation mechanism including the liquid discharge head and circulating the liquid is provided.
The liquid circulation mechanism is
Between the first liquid feed pump for pressurization and the second liquid feed pump for decompression, and the second liquid feed pump and the first liquid feed pump for generating a differential pressure for circulating the liquid to the liquid discharge head. Includes an intermediate tank located in and connected to the second and first liquid feed pumps via the fluid path.
The intermediate tank includes a gas-liquid separation unit that separates the gas mixed in the liquid flowing from the second liquid feeding pump from the liquid.
The gas-liquid separation unit includes a gas-liquid separation circulation including a circulation pump that collects the liquid discharged from the end of the fluid path from the second liquid feed pump and returns it to the intermediate tank via the gas-liquid separation member. Including the route,
The flow rate by the circulation pump is larger than the flow rate by the second liquid feed pump.
The position where the liquid is discharged from the end of the fluid path from the second liquid feed pump is the deep part of the intermediate tank.
A device that discharges a liquid. The liquid according to any one of claims 1 to 7 , wherein the intermediate tank is provided with an air release valve, and the gas-liquid separation unit is arranged at a position away from the air release valve in the intermediate tank. A device that discharges. The device for discharging the liquid according to any one of claims 1 to 8 , wherein the gas-liquid separation member is a filter. The device for discharging the liquid according to any one of claims 1 to 8 , wherein the gas-liquid separation member is a degassing module.

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