JP2021017029A - Image formation device - Google Patents

Abstract

To provide an image formation device capable of monitoring an amount of a waste liquid stored in a waste liquid storage part without using a sensor.SOLUTION: An image formation device includes a deaeration part which uses a gas transmission film capable of transmitting a gas remaining in an ink to remove the gas remaining in the ink; a waste liquid storage part 66 which stores a liquid component contained in the ink, which is transmitted through the gas transmission film with the remaining gas, as a waste liquid; and an estimation part which estimates an amount of the waste liquid stored in the waste liquid storage part based on the time for removing the gas remaining in the ink.SELECTED DRAWING: Figure 3

Description

The present invention relates to an image forming apparatus.

Conventionally, there is an inkjet image forming apparatus that forms an image on a recording medium by ejecting ink from a plurality of nozzles provided in an image forming head on a recording medium conveyed by the conveying device.

In such an inkjet image forming / recording device, if the gas dissolved in the ink becomes bubbles and remains in the ink, a ejection failure may occur at the time of ejecting the ink. Therefore, in the conventional inkjet image forming apparatus, a degassing module is arranged between the flow paths of the ink before the ink is supplied to the inkjet head, and the degassing module removes the bubbles dissolved in the ink. The composition is adopted.

As the degassing module, a device in which a plurality of hollow fiber membranes are held in a tubular member capable of depressurizing is generally used (see, for example, Patent Document 1). In the degassing module using this hollow fiber membrane, bubbles dissolved in the ink flowing in the hollow fiber membrane are reduced to a vacuum by suction of a vacuum pump while flowing ink through the hollow fiber membrane. Can be removed.

By the way, in the ink degassing module using the hollow fiber membrane, the liquid component contained in the ink may permeate through the hollow fiber membrane together with the air bubbles, for example, due to the deterioration of the hollow fiber membrane. In this case, there is a problem that the liquid component that has passed through the hollow fiber membrane flows into the vacuum path through which the air bubbles flow and clogs the vacuum path, which in turn causes a failure in the vacuum pump.

To solve this problem, a technology to prevent clogging of the vacuum path by providing a waste liquid tank (waste liquid storage unit) that stores the liquid component that has passed through the hollow fiber membrane as waste liquid between the degassing module and the vacuum pump. It has been proposed (see, for example, Patent Document 2). Here, the amount of waste liquid stored in the waste liquid tank is monitored based on the detection result of the sensor that detects the weight and liquid level position of the waste liquid, and when the amount of waste liquid reaches a predetermined amount, a user (for example, a serviceman) ) Cleans (removes) the waste liquid stored in the waste liquid tank.

JP 2015-168257 Japanese Unexamined Patent Publication No. 2008-238127

However, in the conventional technique of monitoring the amount of waste liquid based on the detection result of the sensor, there are problems that a space for arranging the sensor is required and the cost for providing the sensor increases.

An object of the present invention is to provide an image forming apparatus capable of monitoring the amount of waste liquid stored in a waste liquid storage unit without using a sensor.

The image forming apparatus according to the present invention is
A degassing part that removes the dissolved gas in the ink using a gas permeable film that can permeate the dissolved gas in the ink.
A waste liquid storage unit that stores the liquid component contained in the ink as a waste liquid that has permeated the gas permeable membrane together with the dissolved gas.
An estimation unit that estimates the amount of the waste liquid stored in the waste liquid storage unit based on the time for removing the dissolved gas in the ink, and an estimation unit.
To be equipped.

According to the present invention, the amount of waste liquid stored in the waste liquid storage unit can be monitored without using a sensor.

It is a figure which shows the schematic structure of the inkjet image forming apparatus. It is a schematic diagram which shows the structure of a head unit. It is a figure which shows the structure of the ink supply mechanism which supplies ink to an image formation head. It is a block diagram which shows the main functional structure of an inkjet image forming apparatus. It is a figure which shows the relationship between the decompression time for decompressing the air pressure in a degassing part, and the amount of waste liquid stored in a waste liquid storage part. It is a flowchart which shows the example of the storage amount estimation processing. It is a flowchart which shows the example of the warning confirmation processing. It is a figure which shows the relationship between the decompression time for decompressing the air pressure in a degassing part, and the amount of waste liquid stored in a waste liquid storage part. It is a flowchart which shows the example of the storage amount estimation processing.

Hereinafter, the present embodiment will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an inkjet image forming apparatus 1. The inkjet image forming apparatus 1 includes a feeding unit 10, an image forming unit 20, a paper ejection unit 30, and a control unit 40 (see FIG. 4).

The inkjet image forming apparatus 1 (functioning as the "image forming apparatus" of the present invention) conveys the recording medium P stored in the paper feeding unit 10 to the image forming unit 20 under the control of the control unit 40, and conveys the recording medium P to the image forming unit 20. An image is formed on the recording medium P at No. 20, and the recording medium P on which the image is formed is conveyed to the paper ejection unit 30. As the recording medium P, in addition to paper such as plain paper and coated paper, various media such as cloth or sheet-shaped resin capable of fixing the ink landed on the surface can be used.

The paper feed unit 10 includes a paper feed tray 11 for storing the recording medium P, and a medium supply unit 12 for transporting and supplying the recording medium P from the paper feed tray 11 to the image forming unit 20. The medium supply unit 12 includes a ring-shaped belt whose inside is supported by two rollers, and the recording medium P is transferred from the paper feed tray 11 by rotating the rollers with the recording medium P placed on the belt. It is conveyed to the image forming unit 20.

The image forming unit 20 includes a transport unit 21, a delivery unit 22, a heating unit 23, a head unit 24, a fixing unit 25, a delivery unit 28, and the like.

The transport unit 21 holds the recording medium P mounted on the transport surface 211a (mounting surface) of the cylindrical transport drum 211, and the transport drum 211 extends in the X direction (the direction perpendicular to the paper surface in FIG. 1). By rotating around the rotating shaft (cylindrical shaft) and moving around, the recording medium P on the transport drum 211 is transported in the transport direction (Y direction). The transport drum 211 includes a claw portion and an intake portion (not shown) for holding the recording medium P on the transport surface 211a. The recording medium P is held on the transport surface 211a by pressing the end portion by the claw portion and attracting the recording medium P to the transport surface 211a by the intake portion. The transport unit 21 is connected to a transport drum motor (not shown) for rotating the transport drum 211. The transfer drum 211 rotates by an angle proportional to the amount of rotation of the transfer drum motor.

The delivery unit 22 delivers the recording medium P conveyed by the medium supply unit 12 of the paper feed unit 10 to the transfer unit 21. The delivery unit 22 is provided at a position between the medium supply unit 12 and the transfer unit 21 of the paper feed unit 10, and one end of the recording medium P conveyed from the medium supply unit 12 is held by the swing arm unit 221 and picked up. , Delivered to the transport unit 21 via the delivery drum 222.

The heating unit 23 is provided between the arrangement position of the transfer drum 222 and the arrangement position of the head unit 24, and the recording medium P conveyed by the transfer unit 21 has a temperature within a predetermined temperature range. Heat P. The heating unit 23 has, for example, an infrared heater or the like, and energizes the infrared heater based on a control signal supplied from the control unit 40 (see FIG. 4) to heat the infrared heater.

The head unit 24 connects the recording medium P to the recording medium P from a nozzle opening provided on the ink ejection surface facing the transport surface 211a of the transport drum 211 at an appropriate timing according to the rotation of the transport drum 211 holding the recording medium P. On the other hand, ink is ejected to form an image. The head unit 24 is arranged so that the ink ejection surface and the transport surface 211a are separated by a predetermined distance. In the inkjet image forming apparatus 1 according to the present embodiment, four head units 24 corresponding to four colors of inks of yellow (Y), magenta (M), cyan (C), and black (K) are used on the recording medium P. They are arranged so as to be arranged at predetermined intervals in the order of Y, M, C, and K colors from the upstream side in the transport direction.

FIG. 2 is a schematic view showing the configuration of the head unit 24. Here, the surface of the head unit 24 facing the transport surface 211a of the transport drum 211 is shown.

The head unit 24 includes four image forming heads 242 attached to the attachment member 244. Each of the image forming heads 242 is provided with a plurality of image forming elements (recording elements) each having a pressure chamber for storing ink, a piezoelectric element provided on the wall surface of the pressure chamber, and a nozzle 243. When a drive signal for deforming the piezoelectric element is input to this image forming element, the pressure chamber is deformed due to the deformation of the piezoelectric element, the pressure in the pressure chamber changes, and ink is ejected from a nozzle communicating with the pressure chamber. ..

In the image forming head 242, two nozzle rows consisting of nozzles 243 arranged at equal intervals in a direction intersecting the transport direction of the recording medium P (in the present embodiment, a direction orthogonal to the transport direction, that is, the X direction) are arranged. It is formed. These two nozzle rows are provided so that the arrangement positions of the nozzles 243 are displaced from each other in the X direction by half of the arrangement interval of the nozzles 243 in each nozzle row.

The four image forming heads 242 are arranged in a houndstooth pattern so that the arrangement ranges of the nozzle rows in the X direction are seamlessly connected. The arrangement range of the nozzle 243 included in the head unit 24 in the X direction covers the width of the recording medium P conveyed by the transfer unit 21 in the X direction of the region where the image is formed, and the head unit 24. The position is fixed and used with respect to the rotation axis of the transport drum 211 when the image is formed. That is, the head unit 24 has a line head capable of ejecting ink over the image forming width in the X direction with respect to the recording medium P, and the inkjet image forming apparatus 1 is a single-pass type inkjet image forming apparatus. Is.

The number of nozzle rows included in the image forming head 242 may be one or three or more instead of two. Further, the number of image forming heads 242 included in the head unit 24 may be three or less or five or more instead of four.

As the ink ejected from the nozzle of the image forming element, an ink having a property of changing its phase into a gel or sol depending on the temperature and being cured by irradiating with energy rays such as ultraviolet rays is used. Further, in the present embodiment, an ink that is gel-like at room temperature and becomes sol-like when heated is used. The head unit 24 includes an ink heating unit (not shown) that heats the ink stored in the head unit 24. The ink heating unit operates under the control of the control unit 40 and heats the ink to a sol-like temperature.

The image forming head 242 ejects the heated and sol-like ink. When this sol-like ink is ejected onto the recording medium P, the ink droplets land on the recording medium P and then are naturally cooled so that the ink quickly becomes a gel and solidifies on the recording medium P.

The fixing unit 25 has a light emitting unit arranged over the width of the transport unit 21 in the X direction, and irradiates the recording medium P mounted on the transport unit 21 with energy rays such as ultraviolet rays from the light emitting unit. Then, the ink ejected on the recording medium P is cured and fixed. The light emitting portion of the fixing portion 25 is arranged to face the transport surface 211a from the arrangement position of the head unit 24 to the arrangement position of the delivery drum 281 of the delivery unit 28 in the transfer direction.

The delivery unit 28 has a cylindrical transfer drum 281 that transfers the recording medium P from the transfer unit 21 to the belt loop 282, and a belt loop 282 having a ring-shaped belt whose inside is supported by two rollers. The recording medium P delivered from the transfer unit 21 onto the belt loop 282 by the transfer drum 281 is conveyed by the belt loop 282 and sent to the paper ejection unit 30.

The paper ejection unit 30 has a plate-shaped paper ejection tray 31 on which the recording medium P sent out from the image forming unit 20 by the delivery unit 28 is placed.

Next, with reference to FIG. 3, the configuration of the ink supply mechanism 60 that supplies ink to the image forming head 242 in the inkjet image forming apparatus 1 will be described.

As shown in FIG. 3, the ink supply mechanism 60 includes a main tank 62, a degassing unit 64, a waste liquid storage unit 66, a vacuum pump 68, a sub tank 70, a degassing air release valve 72, a temperature detection unit 74, and a pressure detection unit 76. To be equipped.

The main tank 62 is provided outside the head unit 24, and stores ink of a color (yellow (Y), magenta (M), cyan (C), or black (K)) corresponding to the head unit 24. The ink stored in the main tank 62 is pumped out by a supply pump (not shown) that operates based on a control signal supplied from the control unit 40 (see FIG. 4), and is pumped out by the ink flow path and the degassing unit 64. It is supplied to the sub tank 70 via.

The sub tank 70 stores ink pumped from the main tank 62 and supplied to the image forming head 242. In the present embodiment, a metal container having a capacity of about 40 liters is used as the sub tank 70. The sub tank 70 is a container open to the outside, and is maintained at substantially atmospheric pressure regardless of an increase or decrease in the amount of ink.

The degassing unit 64 removes the dissolved gas in the ink that has flowed into the degassing unit 64 from the main tank 62 via the ink flow path (more specifically, degass the dissolved gas from the ink). Do. The ink degassed by the degassing unit 64 is sent to the sub tank 70.

The degassing unit 64 and the vacuum pump 68 are connected by a vacuum tube (not shown), and a vacuum path from the degassing unit 64 to the vacuum pump 68 is formed. When the vacuum pump 68 performs a suction operation to make the inside of the vacuum path a vacuum pressure lower than the atmospheric pressure (pressure within a predetermined negative pressure range), the dissolved gas in the ink is removed in the degassing portion 64, and the dissolved gas in the ink is removed. This removed dissolved gas flows through the vacuum path. The vacuum pump 68 does not necessarily have to bring the inside of the vacuum path to an ultra-high vacuum state, and depressurizes to a degree necessary for degassing. Further, the vacuum pump 68 operates based on the control signal supplied from the control unit 40.

The degassing section 64 is provided with a degassing membrane (functioning as the "gas permeable membrane" of the present invention) having gas permeability that allows gas to permeate but does not allow liquid to permeate. In the degassing section 64, the ink flowing into the degassing section 64 is brought into contact with one surface of the degassing film, and the gas is sucked by the vacuum pump 68 on the other side, so that the dissolved gas in the ink is sucked into the vacuum path. And degas. The configuration of the degassing portion 64 is not particularly limited, but for example, it has a large number of degassing membranes (hollow fiber membranes) forming a large number of hollow fine yarn structures with one end closed, and the other end of the hollow fiber membrane. The inside of the hollow fiber membrane can be depressurized by sucking gas from the side by the vacuum pump 68. In this state, when the ink comes into contact with the membrane surface (outer surface) of the hollow fiber membrane, only the dissolved gas in the ink selectively permeates the membrane surface and is sucked into the hollow fiber membrane, and the ink is degassed. To. The degassing portion 64 may be configured such that the outside of the hollow fiber membrane is depressurized and the dissolved gas in the ink passing through the inside of the hollow fiber membrane is desorbed to the outside of the hollow fiber membrane.

The waste liquid storage unit 66 is provided on a vacuum path through which the dissolved gas removed by the degassing unit 64 flows. For example, due to deterioration of the hollow fiber membrane, the liquid contained in the ink as well as the dissolved gas from the degassing unit 64. When a component permeates the degassing membrane and flows into the vacuum path, the liquid component is stored as a waste liquid. That is, when not only the dissolved gas but also the liquid component is sucked from the degassing unit 64 and flows into the vacuum path, the waste liquid storage section 66 separates the liquid component from the dissolved gas, and the liquid component follows the vacuum path. It is a trap that plays a role of preventing the vacuum pump 68 from causing a failure due to clogging and, by extension, the liquid component being sucked into the vacuum pump 68. The waste liquid storage unit 66 has, for example, a small tank shape, and a liquid component is stored in the bottom portion thereof.

A heating unit (not shown) for heating the vacuum path from the degassing unit 64 to the waste liquid storage unit 66 is provided in the vicinity of the degassing unit 64. With this configuration, even in the case of ultraviolet curable ink whose viscosity has increased due to gelation, it is possible to prevent poor liquid transfer from the degassing unit 64 to the waste liquid storage unit 66 for the liquid component flowing into the vacuum path. it can.

The degassing air release valve 72 is a valve for opening the inside of the vacuum path between the degassing unit 64 and the vacuum pump 68 to the atmosphere. The degassing atmosphere release valve 72 is controlled to open so that the degassing unit 64 changes from the vacuum state to the atmospheric pressure state in order to maintain the degassing unit 64, for example, when the power supply of the inkjet image forming apparatus 1 is stopped. Due to this opening control, the liquid component remaining in the degassing membrane of the degassing section 64 or in the degassing section 64 (specifically, outside the degassing film) is removed from the degassing section 64 to the waste liquid storage section 66. Is discharged to. The degassing atmosphere release valve 72 operates based on a control signal supplied from the control unit 40.

The temperature detection unit 74 is composed of, for example, a thermistor (wet contact thermistor), detects the temperature of the ink flowing into the degassing unit 64 from the main tank 62, and outputs the detected temperature to the control unit 40.

The pressure detection unit 76 detects the air pressure in the vacuum path between the degassing unit 64 and the vacuum pump 68, and outputs the detected air pressure to the control unit 40.

FIG. 4 is a block diagram showing a main functional configuration of the inkjet image forming apparatus 1. The inkjet image forming apparatus 1 includes a heating unit 23, a head driving unit 241 and an image forming head 242, a fixing unit 25, a control unit 40, a transport driving unit 51, and an operation display unit 52 (the "notifying unit" of the present invention). It is provided with an input / output interface 53 and the like.

The head drive unit 241 supplies image data from the nozzle 243 of the image forming head 242 by supplying a driving signal for deforming the piezoelectric element according to the image data at an appropriate timing to the image forming element of the image forming head 242. The amount of ink corresponding to the pixel value of is ejected.

The control unit 40 includes a CPU 41 (Central Processing Unit), a RAM 42 (Random Access Memory), a ROM 43 (Read Only Memory), and a storage unit 44. The control unit 40 functions as an "estimation unit", a "time calculation unit", a "vacuum control unit", a "reset unit", and an "emission control unit" of the present invention.

The CPU 41 reads various control programs and setting data stored in the ROM 43, stores them in the RAM 42, executes the programs, and performs various arithmetic processes. In addition, the CPU 41 controls the overall operation of the inkjet image forming apparatus 1.

The RAM 42 provides the CPU 41 with a working memory space and stores temporary data. The RAM 42 may include a non-volatile memory.

The ROM 43 stores various control programs, setting data, and the like executed by the CPU 41. Instead of the ROM 43, a rewritable non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

The storage unit 44 stores a print job (image formation command) input from the external device 2 via the input / output interface 53, image data related to the print job, and the like. Among them, the print job includes information related to the type of the recording medium P forming the image (for example, the size and thickness of the recording medium P) in addition to the information specifying the image data related to the image to be formed. As the storage unit 44, for example, an HDD (Hard Disk Drive) may be used, or a DRAM (Dynamic Random Access Memory) or the like may be used in combination.

The transfer drive unit 51 supplies a drive signal to the transfer drum motor of the transfer drum 211 based on the control signal supplied from the control unit 40 to rotate the transfer drum 211 at a predetermined speed and timing.

Further, the transport drive unit 51 supplies a drive signal to the motor for operating the medium supply unit 12, the delivery unit 22, and the delivery unit 28 based on the control signal supplied from the control unit 40, and supplies the drive signal to the recording medium P. Supply to the transport unit 21 and discharge from the transport unit 21.

The operation display unit 52 includes a display device such as a liquid crystal display or an organic EL display, and an input device such as an operation key and a touch panel arranged on the screen of the display device. The operation display unit 52 displays various information on the display device, converts the user's input operation to the input device into an operation signal, and outputs the operation signal to the control unit 40.

The input / output interface 53 mediates the transmission and reception of data between the external device 2 and the control unit 40. The input / output interface 53 is composed of, for example, various serial interfaces, various parallel interfaces, or a combination thereof.

The external device 2 is, for example, a personal computer, and supplies print jobs, image data, and the like to the control unit 40 via the input / output interface 53.

By the way, in the conventional inkjet image forming apparatus 1, the amount of waste liquid stored in the waste liquid storage unit 66 is monitored based on the detection result of the sensor that detects the weight and the liquid level position of the waste liquid, and the amount of waste liquid is a predetermined amount. When the amount reaches (for example, the full amount), the waste liquid stored in the waste liquid tank is cleaned (removed) by the user (for example, a serviceman). However, in the conventional technique of monitoring the amount of waste liquid based on the detection result of the sensor, there are problems that a space for arranging the sensor is required and the cost for providing the sensor increases.

Therefore, in the present embodiment, the control unit 40 stores the amount of waste liquid in the waste liquid storage unit 66 based on the decompression time for reducing the air pressure in the degassing unit 64 when the degassing unit 64 performs degassing. To estimate.

The present inventors conducted a test by variously changing the set value set for the vacuum pressure (set value peculiar to the degassing unit 64) when reducing the air pressure in the degassing unit 64, and as a result, the degassing unit It was found that a substantially proportional relationship is established between the decompression time for decompressing the air pressure in 64 and the amount of waste liquid stored in the waste liquid storage unit 66 that the amount of storage increases as the decompression time increases. It was also found that the smaller the set value (absolute value) of the vacuum pressure, that is, the closer to the atmospheric pressure, the smaller the slope of the proportional relationship. In the present embodiment, utilizing these findings, the amount of waste liquid stored in the waste liquid storage unit 66 is estimated from the decompression time for reducing the air pressure in the degassing unit 64.

The storage unit 44 stores in advance the relationship information indicating the relationship between the decompression time for reducing the air pressure in the degassing unit 64 and the amount of waste liquid stored in the waste liquid storage unit 66 for each set value of the vacuum pressure. There is.

FIG. 5 approximates the relationship between the decompression time for depressurizing the air pressure in the degassing unit 64 and the amount of waste liquid stored in the waste liquid storage unit 66 when the set value of the vacuum pressure is constant. As shown by the solid line L in FIG. 5, as the decompression time T becomes longer, the stored amount W increases proportionally. By referring to the relational information stored in the storage unit 44, the control unit 40 estimates that the amount of waste liquid stored reaches w1 when the decompression time reaches t1. Further, the control unit 40 can estimate that the stored amount of the waste liquid reaches w2 (full amount) when the decompression time reaches t2 by referring to the relational information stored in the storage unit 44. As a result, the remaining time (t2-t1) until the stored amount of the waste liquid reaches the full amount (predetermined amount or more) at the stage where the decompression time is t1 can be calculated.

In the present embodiment, at the timing when the remaining time until the stored amount of waste liquid reaches the full amount is less than a predetermined time (for example, 100 hours) (in other words, the timing when the stored amount of waste liquid approaches the full amount). The control unit 40 causes the operation display unit 52 to display a warning regarding cleaning of the waste liquid storage unit 66 (for example, an instruction to clean the waste liquid stored in the waste liquid storage unit 66). A user (for example, a serviceman) who sees the display can clean (remove) the waste liquid stored in the waste liquid storage unit 66 at an appropriate timing before the stored amount of the waste liquid reaches the full amount.

FIG. 6 is a flowchart showing an example of the storage amount estimation process. The process of step S101 in FIG. 6 is executed by turning on the power of the inkjet image forming apparatus 1. In the flowchart of FIG. 6, it is assumed that the set value of the vacuum pressure when the air pressure in the degassing unit 64 is reduced is constant.

First, the control unit 40 executes the warning confirmation process (step S101). FIG. 7 is a flowchart showing an example of the warning confirmation process.

In the flowchart of FIG. 7, first, the control unit 40 determines whether or not a warning regarding cleaning of the waste liquid storage unit 66 is displayed on the operation display unit 52 (step S201). As a result of the determination, when the warning regarding cleaning of the waste liquid storage unit 66 is not displayed (step S201, NO), the inkjet image forming apparatus 1 ends the process in FIG. 7.

On the other hand, when a warning regarding cleaning of the waste liquid storage unit 66 is displayed (step S201, YES), the control unit 40 determines whether or not the cleaning completion button has been pressed by the user (step S202). Here, the cleaning complete button notifies the inkjet image forming apparatus 1 that the cleaning is completed after the user who sees the warning regarding the cleaning of the waste liquid storage unit 66 cleans the waste liquid stored in the waste liquid storage unit 66. It is a button to press for.

As a result of the determination, if the cleaning completion button is not pressed (step S202, NO), the process returns to the previous step S202. On the other hand, when the cleaning completion button is pressed (step S202, YES), the control unit 40 controls the operation display unit 52 to end the warning display regarding cleaning of the waste liquid storage unit 66 (step S203).

Finally, the control unit 40 resets the depressurization time (vacuum control time) for depressurizing the air pressure in the degassing unit 64, that is, sets it to 0 (step S204). When the process of step S204 is completed, the inkjet image forming apparatus 1 ends the process in FIG. 7.

Returning to the flowchart of FIG. 6, in step S102, the control unit 40 acquires the detection result of the temperature detection unit 74, and whether or not the temperature of the ink flowing into the degassing unit 64 from the main tank 62 is equal to or higher than the predetermined temperature. Judge about. Here, the predetermined temperature is a temperature at which the ink undergoes a phase change from a gel-like state to a sol-like state when heated. When the temperature of the ink exceeds a predetermined temperature, the ink is sufficiently melted, and when the degassing unit 64 degass, not only the dissolved gas in the ink but also the liquid component permeates the degassing film and the vacuum path. There is a possibility of inflow.

As a result of the determination, when the temperature of the ink is lower than the predetermined temperature (step S102, NO), the process returns to before step S102. On the other hand, when the temperature of the ink is equal to or higher than a predetermined temperature (step S102, YES), the control unit 40 performs degassing to remove the dissolved gas in the ink flowing into the degassing unit 64 from the main tank 62. Control of the degassing unit 64 is started (step S103). Specifically, the control unit 40 controls the vacuum pump 68 so that the air pressure in the degassing unit 64 is reduced to the set value of the vacuum pressure based on the detection result of the pressure detection unit 76.

Next, the control unit 40 determines whether or not the power of the inkjet image forming apparatus 1 has been turned off (step S104). As a result of the determination, when the power of the inkjet image forming apparatus 1 is not turned off (step S104, NO), the process returns to the step before step S104. On the other hand, when the power of the inkjet image forming apparatus 1 is turned off (step S104, YES), the control unit 40 ends the control of the degassing unit 64 started in step S103 (step S105).

Next, the control unit 40 determines the time (which can be calculated by the counter function of the control unit 40) from the start of the control of the degassing unit 64 in step S103 to the end of the control of the degassing unit 64 in step S105. The pressure in the degassing unit 64 is integrated into the depressurizing time for depressurizing. Then, the control unit 40 refers to the relational information stored in the storage unit 44, and estimates the storage amount (the amount of waste liquid stored in the waste liquid storage unit 66) corresponding to the decompression time after the integration (step S106). ).

Next, the control unit 40 reaches from the decompression time after the integration (for example, t1 in FIG. 5) to the time when the stored amount of the waste liquid reaches a predetermined amount (for example, the full amount) (for example, t2 in FIG. 5). Is calculated, and it is determined whether or not the remaining time is equal to or less than the predetermined time (step S107). As a result of the determination, when the remaining time is not less than or equal to the predetermined time (step S107, NO), the inkjet image forming apparatus 1 ends the process in FIG.

On the other hand, when the remaining time is less than or equal to a predetermined time (step S107, YES), the control unit 40 controls the operation display unit 52 to display a warning regarding cleaning of the waste liquid storage unit 66 (step S108). When the process of step S108 is completed, the inkjet image forming apparatus 1 ends the process in FIG.

In the above flowchart, the control unit 40 degass the liquid component remaining in the degassing unit 64 (specifically, degassing in the degassing unit 64) while the degassing unit 64 performs degassing. Discharge control may be performed to discharge the liquid component (the liquid component accumulated inside and outside the air membrane) from the degassing unit 64 to the waste liquid storage unit 66. Specifically, the control unit 40 controls the degassing atmosphere release valve 72 to open so that the degassing unit 64 changes from the vacuum state to the atmospheric pressure state. As a result, the liquid component remaining in the degassing unit 64 can also be discharged to the waste liquid storage unit 66 for cleaning. In this case, the control unit 40 may perform discharge control every time a predetermined time (for example, 2 hours) elapses while the degassing unit 64 is performing degassing. Then, the control unit 40 may estimate the amount of waste liquid stored in the waste liquid storage unit 66 each time the discharge control is performed. As a result, whether or not the amount of waste liquid stored is approaching the full amount is monitored at shorter intervals than when the amount of waste liquid stored is estimated after the power of the inkjet image forming apparatus 1 is turned off. If necessary, a warning regarding cleaning of the waste liquid storage unit 66 can be displayed.

As described in detail above, the inkjet image forming apparatus 1 according to the present embodiment is a degassing unit 64 having a degassing film (gas permeable film) capable of permeating the dissolved gas in the ink, and is a vacuum pump. A vacuum in which the degassing section 64, which removes the dissolved gas in the ink through the degassing film by reducing the pressure in the degassing section 64 to the vacuum pressure by 68, and the dissolved gas removed by the degassing section 64 flow. Waste liquid based on the waste liquid storage unit 66, which is provided on the path and permeates the degassing film together with the dissolved gas, and stores the liquid component contained in the ink as waste liquid, and the depressurization time for reducing the pressure in the degassing unit 64. A control unit 40 (estimation unit) for estimating the amount of waste liquid stored in the storage unit 66 is provided.

According to the present embodiment configured in this way, the amount of waste liquid stored in the waste liquid storage unit 66 is based on the decompression time (which can be calculated by the counter function of the control unit 40) for reducing the air pressure in the degassing unit 64. Presumed. Therefore, as compared with the conventional technique of monitoring the amount of waste liquid based on the detection result of the sensor, a space for arranging the sensor is not required and the cost for providing the sensor is not increased. Therefore, the amount of waste liquid stored in the waste liquid storage unit 66 can be monitored without using a sensor, that is, with a simple configuration.

In the above embodiment, an example in which the set value of the vacuum pressure when the air pressure in the degassing unit 64 is reduced is constant has been described, but the present invention is not limited to this. For example, the set value of the vacuum pressure may be changed each time the control for reducing the air pressure in the degassing unit 64 is executed. FIG. 8 shows a depressurizing time (each time the power is turned on) for reducing the air pressure in the degassing unit 64 when the set value of the vacuum pressure is variable each time the power of the inkjet image forming apparatus 1 is turned on. The relationship between the cumulative decompression time) and the amount of waste liquid stored in the waste liquid storage unit 66 is shown.

In FIG. 8, the solid line L1 was degassed for the first time by reducing the air pressure in the degassing unit 64 after the power of the inkjet image forming apparatus 1 was turned on and before it was turned off. In this case, the proportional relationship between the decompression time and the amount of waste liquid stored in the waste liquid storage unit 66 is shown. As shown in FIG. 8, the decompression time (cumulative time) reaches t1 and the stored amount (cumulative amount) of the waste liquid reaches w1 at the timing when the first degassing is completed.

In FIG. 8, the solid line L2 was degassed for the second time by reducing the air pressure in the degassing unit 64 after the power of the inkjet image forming apparatus 1 was turned on and before it was turned off. In this case, the proportional relationship between the decompression time and the amount of waste liquid stored in the waste liquid storage unit 66 is shown. As shown in FIG. 8, the decompression time (cumulative time) reaches t2 and the stored amount (cumulative amount) of the waste liquid reaches w2 at the timing when the second degassing is completed.

In FIG. 8, the solid line L3 is degassed for the third time by reducing the air pressure in the degassing unit 64 after the power of the inkjet image forming apparatus 1 is turned on and before it is turned off. In this case, the proportional relationship between the decompression time and the amount of waste liquid stored in the waste liquid storage unit 66 is shown. As shown in FIG. 8, the decompression time (cumulative time) reaches t3 and the stored amount (cumulative amount) of the waste liquid reaches w3 at the timing when the third degassing is completed.

In FIG. 8, the solid line L4 is degassed for the fourth time by reducing the air pressure in the degassing section 64 after the power of the inkjet image forming apparatus 1 is turned on and before it is turned off. The proportional relationship between the decompression time and the amount of waste liquid stored in the waste liquid storage unit 66 in the case is shown. As shown in FIG. 8, the decompression time (cumulative time) reaches t4 and the stored amount (cumulative amount) of the waste liquid reaches w4 at the timing when the fourth degassing is completed.

In FIG. 8, the solid line L5 is degassed for the fifth time by reducing the air pressure in the degassing unit 64 after the power of the inkjet image forming apparatus 1 is turned on and before it is turned off. In this case, the proportional relationship between the decompression time and the amount of waste liquid stored in the waste liquid storage unit 66 is shown. As shown in FIG. 8, the decompression time (cumulative time) reaches t5 and the stored amount (cumulative amount) of the waste liquid reaches w5 at the timing when the fifth degassing is completed.

In FIG. 8, the solid line L6 is degassed for the sixth time by reducing the air pressure in the degassing unit 64 after the power of the inkjet image forming apparatus 1 is turned on and before it is turned off. In this case, the proportional relationship between the decompression time and the amount of waste liquid stored in the waste liquid storage unit 66 is shown. As shown in FIG. 8, the decompression time (cumulative time) reaches t6 and the stored amount (cumulative amount) of the waste liquid reaches w6 at the timing when the sixth degassing is completed.

In FIG. 8, the solid line L7 was degassed for the seventh time by reducing the air pressure in the degassing unit 64 after the power of the inkjet image forming apparatus 1 was turned on and before it was turned off. In this case, the proportional relationship between the decompression time and the amount of waste liquid stored in the waste liquid storage unit 66 is shown. As shown in FIG. 8, the decompression time (cumulative time) reaches t7 and the stored amount (cumulative amount) of the waste liquid reaches w7 at the timing when the seventh degassing is completed.

In FIG. 8, the dotted line L8 is a case where the air pressure in the degassing section 64 is reduced by using the same vacuum pressure setting value as when the seventh degassing is performed, and the eighth degassing is performed. The proportional relationship (prediction line) between the decompression time and the amount of waste liquid stored in the waste liquid storage unit 66 is shown. That is, the slope of the proportional relationship on the solid line L7 and the slope of the proportional relationship on the dotted line L8 are the same. In this case, the control unit 40 can estimate that the stored amount of the waste liquid becomes w8 (full amount) when the decompression time reaches t8, and the stored amount of the waste liquid is full at the stage where the decompression time is t7. The remaining time T1 (= t8-t7) until the amount (predetermined amount or more) is reached can be calculated. The slopes of the solid lines L1 to L7 are different from each other because the set value of the vacuum pressure is changed every time the power of the inkjet image forming apparatus 1 is turned on.

FIG. 9 is a flowchart showing an example of the storage amount estimation process. The process of step S301 in FIG. 9 is executed by turning on the power of the inkjet image forming apparatus 1. In the flowchart of FIG. 9, the set value of the vacuum pressure can be changed by the user each time the control for reducing the air pressure in the degassing unit 64 is executed.

First, the control unit 40 executes the warning confirmation process (step S301). Since the warning confirmation process is the same as the flowchart shown in FIG. 7, the description thereof is omitted here.

Next, the control unit 40 acquires the detection result of the temperature detection unit 74 and determines whether or not the temperature of the ink flowing from the main tank 62 into the degassing unit 64 is equal to or higher than a predetermined temperature (step S302).

As a result of the determination, when the temperature of the ink is lower than the predetermined temperature (step S302, NO), the process returns to before step S302. On the other hand, when the temperature of the ink is equal to or higher than the predetermined temperature (step S302, YES), the control unit 40 degass the ink so as to remove the dissolved gas flowing into the degassing unit 64 from the main tank 62. Control of the degassing unit 64 is started (step S303). Specifically, the control unit 40 controls the vacuum pump 68 so that the air pressure in the degassing unit 64 is reduced to the set value of the vacuum pressure based on the detection result of the pressure detection unit 76.

Next, the control unit 40 acquires a set value set for the vacuum pressure at the time of degassing (step S304). Next, the control unit 40 determines whether or not the power of the inkjet image forming apparatus 1 has been turned off (step S305). As a result of the determination, when the power of the inkjet image forming apparatus 1 is not turned off (step S305, NO), the process returns to the step before step S305. On the other hand, when the power of the inkjet image forming apparatus 1 is turned off (step S305, YES), the control unit 40 ends the control of the degassing unit 64 started in step S303 (step S306).

Next, the control unit 40 determines the time from the start of control of the degassing unit 64 in step S303 to the end of control of the degassing unit 64 in step S306 (which can be calculated by the counter function of the control unit 40). It is calculated as the decompression time for depressurizing the air pressure in the degassing unit 64. Then, the control unit 40 refers to the relational information stored in the storage unit 44 and the set value acquired in step S304, and the storage amount corresponding to the calculated decompression time (the amount of waste liquid stored in the waste liquid storage unit 66). ) Is estimated (step S307). Then, the control unit 40 uses the decompression time calculated in step S307 and the estimated storage amount to clean the waste liquid stored in the waste liquid storage unit 66 by the user (specifically, FIG. The decompression time (cumulative time) and the storage amount (cumulative amount) in the decompression time (after the decompression time is reset in step S204 of 7) are updated.

Next, the control unit 40 uses the set value of the vacuum pressure acquired in step S304, the updated decompression time (cumulative time), and the stored amount (cumulative amount) to determine the air pressure in the degassing unit 64. Generates a prediction line (see, for example, the dotted line L8 in FIG. 8) showing the proportional relationship between the decompression time when the pressure is reduced and the next degassing is performed and the amount of waste liquid stored in the waste liquid storage unit 66 (see, for example, the dotted line L8 in FIG. 8). Step S308).

Next, the control unit 40 refers to the prediction line generated in step S308, and from the updated decompression time (for example, t7 in FIG. 8), the time for the stored amount of waste liquid to reach the full amount (for example, FIG. 8). The remaining time until t8) is calculated, and it is determined whether or not the remaining time is equal to or less than the predetermined time (step S309). As a result of the determination, when the remaining time is not less than or equal to the predetermined time (step S309, NO), the inkjet image forming apparatus 1 ends the process in FIG.

On the other hand, when the remaining time is less than or equal to a predetermined time (step S309, YES), the control unit 40 controls the operation display unit 52 to display a warning regarding cleaning of the waste liquid storage unit 66 (step S310). When the process of step S310 is completed, the inkjet image forming apparatus 1 ends the process in FIG.

In the above flowchart, while the power of the inkjet image forming apparatus 1 is turned on, the vacuum pressure setting value may be changed and degassing may be performed a plurality of times. In this case, the control unit 40 estimates the amount of waste liquid stored in the waste liquid storage unit 66 each time the set value of the vacuum pressure is changed, and generates a prediction line generated based on the set value before the change. Then, the control unit 40 calculates the remaining time until the amount of waste liquid stored reaches the full amount, and when the remaining time is equal to or less than a predetermined time, displays a warning regarding cleaning of the waste liquid storage unit 66.

Further, in the above embodiment, an example of notifying the user by displaying a warning regarding cleaning of the waste liquid storage unit 66 has been described, but the present invention is not limited to this. For example, the user may be notified by outputting a voice warning regarding cleaning of the waste liquid storage unit 66.

Further, in the above-described embodiment, the example in which the recording medium P is conveyed by the conveying drum 211 has been described, but the present invention is not limited to this. For example, the recording medium P may be conveyed by a conveying belt that is supported by two rollers and moves according to the rotation of the rollers. Further, the recording medium P may be conveyed by a conveying member that reciprocates on the same plane.

Further, in the above-described embodiment, the single-pass type inkjet image forming apparatus 1 has been described as an example, but the present invention may be applied to an inkjet image forming apparatus that records an image while scanning the head unit. .. Further, the present invention may be applied to an inkjet image forming apparatus provided with a single nozzle in the head unit.

Further, in the above embodiment, the inkjet image forming apparatus 1 that heats and ejects the ink that is gel-like at room temperature and becomes sol-like by heating into a sol-like ink has been described as an example. Not limited to this, various known inks including inks that are sol or liquid at room temperature may be used.

Further, in the above-described embodiments, all of them are merely examples of embodiment of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

1 Inkjet image forming device 2 External device 10 Paper feeding unit 11 Paper feeding tray 12 Media supply unit 20 Image forming unit 21 Transporting unit 211 Transporting drum 211a Transporting surface 22 Delivery unit 23 Heating unit 24 Head unit 241 Head drive unit 242 Image forming head 243 Nozzle 244 Mounting member 25 Fixing part 28 Delivery part 29 Rotary encoder 30 Paper ejection part 31 Paper ejection tray 40 Control unit 41 CPU
42 RAM
43 ROM
44 Storage unit 51 Transport drive unit 52 Operation display unit 53 Input / output interface 60 Ink supply mechanism 62 Main tank 64 Degassing unit 66 Waste liquid storage unit 68 Vacuum pump 70 Sub tank 72 Degassing air release valve 74 Temperature detection unit 76 Pressure detection unit P recoding media

Claims (13)

A degassing part that removes the dissolved gas in the ink using a gas permeable film that can permeate the dissolved gas in the ink.
A waste liquid storage unit that stores the liquid component contained in the ink as a waste liquid that has permeated the gas permeable membrane together with the dissolved gas.
An estimation unit that estimates the amount of the waste liquid stored in the waste liquid storage unit based on the time for removing the dissolved gas in the ink, and an estimation unit.
An image forming apparatus comprising. The degassing portion has the gas permeable membrane inside, and the dissolved gas in the ink is removed through the gas permeable membrane by reducing the air pressure in the degassing portion to the vacuum pressure by a vacuum pump.
The waste liquid storage unit is provided on a vacuum path through which the dissolved gas removed by the degassing unit flows.
The estimation unit estimates the amount of the waste liquid stored based on the decompression time for depressurizing the air pressure in the degassing unit.
The image forming apparatus according to claim 1. When the temperature of the ink in the degassing section is equal to or higher than a predetermined temperature, the vacuum pump reduces the air pressure in the degassing section.
The image forming apparatus according to claim 2. The estimation unit estimates the storage amount of the waste liquid by referring to the relational information indicating the relationship between the decompression time and the storage amount of the waste liquid.
The image forming apparatus according to claim 2 or 3. The estimation unit estimates the amount of the waste liquid stored according to the value of the vacuum pressure and the decompression time.
The image forming apparatus according to any one of claims 2 to 4. The estimation unit estimates the storage amount of the waste liquid by referring to the relationship information indicating the relationship between the decompression time and the storage amount of the waste liquid for each value of the vacuum pressure.
The image forming apparatus according to claim 5. The value of the vacuum pressure is a set value set for the vacuum pressure.
The image forming apparatus according to claim 5 or 6. Time calculation for calculating the time until the stored amount of the waste liquid reaches a predetermined amount when the air pressure in the degassing part is continuously reduced based on the estimated stored amount of the waste liquid and the value of the vacuum pressure. Department and
When the calculated time is less than or equal to a predetermined time, a notification unit for notifying a warning regarding cleaning of the waste liquid storage unit and a notification unit.
The image forming apparatus according to any one of claims 2 to 7. A pressure detection unit that detects the air pressure inside the degassing unit,
A vacuum control unit that controls the vacuum pump so that the air pressure in the degassing unit is reduced to the vacuum pressure based on the detection result of the pressure detection unit.
The image forming apparatus according to any one of claims 2 to 8. A reset unit for resetting the decompression time after the waste liquid stored in the waste liquid storage unit is removed by the user.
The image forming apparatus according to any one of claims 2 to 9. A discharge control unit for controlling discharge of the liquid component remaining in the degassing unit from the degassing unit to the waste liquid storage unit is provided.
The image forming apparatus according to any one of claims 2 to 10. The discharge control unit performs the discharge control every time a predetermined time elapses.
The image forming apparatus according to claim 11. The estimation unit estimates the amount of the waste liquid stored in the waste liquid storage unit each time the discharge control is performed.
The image forming apparatus according to claim 11 or 12.

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