JP6900711B2 - Inkjet recording device and control method of inkjet recording device - Google Patents

Description

The present invention relates to an inkjet recording device that ejects ink onto a recording medium to form an image, and a control method for the inkjet recording device.

In the inkjet recording device, a piezoelectric element is incorporated in the nozzle substrate of the inkjet head, and ink is ejected from the nozzle of the inkjet head by using the volume change due to the piezoelectric element to form an image on a recording medium. In such an inkjet 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 recording device, a degassing module is arranged between the flow paths of the ink before the ink is supplied to the ink jet head, and the degassing module removes air 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 Patent Document 1). In the degassing module using this hollow fiber membrane, bubbles dissolved in the ink flowing in the hollow fiber membrane can be removed by reducing the pressure inside the tubular member to a vacuum while flowing ink through the hollow fiber membrane. it can.

Japanese Unexamined Patent Publication No. 2015-168257

However, in the degassing module using the hollow fiber membrane, there is a problem that impurities remaining in the ink are clogged in the hollow fiber membrane and degassing cannot be performed, or the ink does not flow in the degassing module. ..

Therefore, an object of the present invention is to provide an inkjet recording device and a control method for the inkjet recording device, which include an inkjet recording device with improved degassing performance.

In order to solve the above problems and achieve the object of the present invention, the inkjet recording apparatus of the present invention ejects an ink tank in which ink is stored and ink supplied from the ink tank from a nozzle to image on a recording medium. It is provided with an inkjet head forming the ink jet head and a degassing device provided on the ink supply path between the ink tank and the ink jet head and removing the gas dissolved in the ink supplied from the ink tank side. Further, a flow rate limiting unit provided on the ink supply path between the ink tank and the degassing unit to limit the flow rate of the ink supplied to the degassing device, and a control for controlling the degassing device and the flow rate limiting unit. It has a part. Further, the degassing device includes a degassing unit that holds the supplied ink in a thin film form, and a pressure control unit that can hold the inside of the degassing unit in a vacuum.

Further, in the control method of the inkjet recording device of the present invention, in the inkjet recording device of the present invention, the control unit controls the flow rate limiting unit to limit the flow rate of the ink supplied into the degassing unit.

According to the present invention, the degassing performance is improved in the degassing device applied to the inkjet recording device.

It is an overall block diagram of the inkjet recording apparatus which concerns on 1st Embodiment of this invention. FIG. 2A is a schematic view of the internal configuration when the head unit is viewed from the side. FIG. 2B is a schematic view of the internal configuration of the head unit when viewed from the recording medium side. It is a block diagram which showed the ink ejection mechanism which consists of an ink supply part and a head unit. It is a schematic block diagram which showed the deaeration device which concerns on 1st Embodiment of this invention in an enlarged manner. It is a block diagram of the control system of an inkjet recording apparatus. It is a flowchart which shows the control method of the flow rate limiting part in the inkjet recording apparatus which concerns on 1st Embodiment of this invention. It is a flowchart which shows the control method of the deaeration device of the inkjet recording apparatus which concerns on 1st Embodiment of this invention. It is a schematic block diagram which concerns on the ink ejection mechanism of the inkjet recording apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram of the control system of the inkjet recording apparatus which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the control method of the deaeration device of the inkjet recording apparatus which concerns on 2nd Embodiment of this invention. It is a schematic block diagram concerning the ink ejection mechanism of the inkjet recording apparatus which concerns on a modification.

Hereinafter, an example of the inkjet recording device according to the embodiment of the present invention and the control method of the inkjet recording device will be described with reference to the drawings. The present invention is not limited to the following examples. In each of the figures described below, the common members are designated by the same reference numerals. The explanation will be given in the following order.
1. 1. First Embodiment 1-1. Overall configuration of inkjet recording device 1-2. Ink ejection mechanism 1-3. Degassing principle 1-4. Control system configuration 1-5. Control method of inkjet recording device (control example of flow rate limiting unit)
1-6. Control method of inkjet recording device (control method of degassing device)
2. Second embodiment (an example in which an intermediate tank is provided in the degassing device and the degassed ink is stored in the intermediate tank).
2-1. Ink ejection mechanism 2-2. Control system configuration 2-3. Control method of inkjet recording device 2-4. Modification example

1. 1. First Embodiment 1-1. Overall Configuration of Inkjet Recording Device FIG. 1 is an overall configuration diagram of the inkjet recording device 1 according to the first embodiment of the present invention (hereinafter referred to as the present embodiment). As shown in FIG. 1, the inkjet recording device 1 of the present embodiment includes a paper feeding unit 10, an image forming unit 20, a paper ejection unit 30, an ink supply unit 40, and a control unit 100 (see FIG. 5). Has. The inkjet recording device 1 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 100, and the image forming unit 20 forms an image on the recording medium P, and the image is produced. The formed recording medium P is ejected to the paper ejection unit 30.

[Paper feed section]
The paper feed unit 10 includes a paper feed tray 11 for storing a recording medium P made of, for example, paper, and a transport unit 12 for transporting the recording medium P from the paper feed tray 11 to the image forming unit 20.

The paper feed tray 11 is a plate-shaped member provided on which one or a plurality of recording media P can be placed. The paper feed tray 11 is provided so as to move up and down according to the amount of the recording medium P placed on the paper feed tray 11, and the highest recording medium P is conveyed by the transport unit 12 in the vertical movement direction. It is held in the position where it is.

The transport unit 12 is placed on a transport mechanism that drives a ring-shaped belt 123 supported by a plurality of (for example, two) rollers 121 and 122 on the inside to transport the recording medium P on the belt 123, or on a paper feed tray 11. It has a supply unit (not shown) that delivers the highest mounted recording medium P onto the belt 123. The transport unit 12 transports the recording medium P delivered on the belt 123 by the supply unit along the belt 123.

[Image forming part]
The image forming unit 20 includes an image forming drum 21, a delivery unit 22, a paper heating unit 23, a head unit 24, an irradiation unit 25, a delivery unit 26, and an image reading sensor 27.

The image forming drum 21 is composed of a cylindrical member, and is rotated counterclockwise by a drive motor (not shown). The image forming drum 21 carries the recording medium P along the cylindrical outer peripheral surface, and conveys the recording medium P as the recording medium P rotates. The transport surface of the image forming drum 21 faces the paper heating unit 23, the head unit 24, and the irradiation unit 25, and the paper heating unit 23, the head unit 24, and the irradiation unit 25 are recorded by the image forming drum 21. The medium P is subjected to processing related to image formation.

As shown in FIG. 1, the delivery unit 22 is provided at a position interposed between the transport unit 12 of the paper feed unit 10 and the image forming drum 21. The delivery unit 22 has a claw portion 221 that supports one end of the recording medium P transported by the transport unit 12, a cylindrical transfer drum 222 that guides the recording medium P supported on the claw portion 221 and the like, and transports the unit 22. The recording medium P on the portion 12 is picked up by the claw portion 221 and placed along the outer peripheral surface of the delivery drum 222 to guide the recording medium P in the direction along the outer peripheral surface of the image forming drum 21 and delivered to the image forming drum 21. ..

The paper heating unit 23 has, for example, a heating wire, and generates heat in response to energization. The paper heating unit 23 is provided near the outer peripheral surface of the image forming drum 21 and is located upstream of the head unit 24 with respect to the conveying direction of the recording medium P by the rotation of the image forming drum 21. Under the control of the control unit 100, the paper heating unit 23 generates heat so that the recording medium P supported on the image forming drum 21 and passing near the paper heating unit 23 reaches a predetermined temperature.

Further, a temperature sensor (not shown) is provided in the vicinity of the paper heating unit 23. Based on the temperature near the paper heating unit 23 detected by the temperature sensor, the control unit 100 so that the recording medium P supported by the image forming drum 21 and passing near the paper heating unit 23 reaches a predetermined temperature. Controls the operation of the paper heating unit 23.

The head unit 24 ejects ink onto the recording medium P supported on the image forming drum 21 to form an image. The head unit 24 is individually provided for each color of C (cyan), M (magenta), Y (yellow), and K (black). In FIG. 1, head units 24 are provided in order corresponding to each color of Y, M, C, and K from the upstream with respect to the transport direction of the recording medium P that is conveyed with the rotation of the image forming drum 21.

The head unit 24 of the present embodiment is provided with a length (width) that covers the entire recording medium P in a direction perpendicular to the transport direction of the recording medium P (width direction of the recording medium P). That is, the inkjet recording device 1 is a one-pass type line head type inkjet recording device. The head unit 24 can form a line head by arranging a plurality of inkjet heads 50 (see FIG. 2A).

2A and 2B are views showing the internal configuration of the head unit 24. FIG. 2A is a schematic view of the internal configuration of the head unit 24 when viewed from the side. FIG. 2B is a schematic view of the internal configuration of the head unit 24 when viewed from the recording medium P side. The view of the head unit 24 from the side is the case where the head unit 24 is viewed from the vertical direction of the head unit 24 and the surface along the vertical direction (X direction) with respect to the paper surface of FIG. Shown.

As shown in FIGS. 2A and 2B, the head unit 24 has a plurality of inkjet heads 50. 2A and 2B show an example in which 16 inkjet heads 50 are provided in two head units 24. The 16 inkjet heads 50 each consist of two inkjet heads 50 as a set to form eight inkjet modules 51.

Each inkjet head 50 has a plurality of nozzles 52. The inkjet head 50 ejects ink from a plurality of nozzles 52 to form an image on a recording medium P supported on an image forming drum 21. That is, the inkjet head 50 is provided so that the plurality of nozzles 52 are exposed on the lower surface side of the head unit 24. As shown in FIG. 2B, each inkjet module 51 composed of two inkjet heads 50 has nozzles 52 arranged in two rows along the X direction.

The eight inkjet modules 51 form, for example, two rows along the X direction, as shown in FIG. 2B. The two rows are arranged so that the inkjet modules 51 are staggered with each other in the direction orthogonal to the X direction.

Further, the head unit 24 is individually provided for each color (CMYK) used for image formation. The inkjet recording apparatus 1 shown in FIG. 1 corresponds to each color in the order of Y, M, C, and K from the upstream along the conveying direction of the recording medium P conveyed with the rotation of the image forming drum 21. A head unit 24 is provided. The configuration of the inkjet head 50 in the head unit 24 and the ink ejection mechanism will be described in detail later.

The irradiation unit 25 irradiates energy rays for curing the ink after the ink used in the inkjet recording device 1 of the present embodiment is ejected onto the recording medium P. The irradiation unit 25 has, for example, a fluorescent tube such as a low-pressure mercury lamp, and the fluorescent tube is made to emit light to irradiate energy rays such as ultraviolet rays. The irradiation unit 25 is provided near the outer peripheral surface of the image forming drum 21 and is provided on the downstream side of the head unit 24 in the transport direction of the recording medium P due to the rotation of the image forming drum 21. The irradiation unit 25 irradiates the recording medium P supported on the image forming drum 21 and ejected the ink with energy rays to cure the ink ejected on the recording medium P by the action of the energy rays.

Fluorescent tubes that emit ultraviolet rays include low-pressure mercury lamps, mercury lamps with an operating pressure of several hundred Pa to 1 MPa, light sources that can be used as germicidal lamps, cold cathode tubes, ultraviolet laser light sources, metal halide lamps, and light emitting diodes. Can be mentioned. Among these, a light source (for example, a light emitting diode) that can irradiate ultraviolet rays with higher illuminance and consumes less power is more desirable. Further, the energy ray is not limited to ultraviolet rays, and may be any energy ray having a property of curing the ink according to the property of the ink, and the light source is also replaced according to the wavelength of the energy ray.

The delivery unit 26 conveys the recording medium P irradiated with energy rays by the irradiation unit 25 from the image forming drum 21 to the paper ejection unit 30. The delivery unit 26 rotationally drives the ring-shaped belt 263 by a plurality of (for example, two) rollers 261,262 to convey the recording medium P on the belt 263, and the recording medium P from the image forming drum 21. It has a cylindrical delivery drum 264 and the like to be delivered to the transfer mechanism. The delivery unit 26 conveys the recording medium P delivered to the belt 263 by the delivery drum 264 by the belt 263 and sends it out to the paper ejection unit 30.

The image reading sensor 27 is composed of an in-line sensor or the like, and reads an image formed on the recording medium P discharged to the delivery unit 26. The read image data is sent to the control unit 100.

[Paper ejection section]
The paper ejection unit 30 stores the recording medium P sent from the image forming unit 20 by the delivery unit 26. The paper ejection unit 30 has a plate-shaped paper ejection tray 31 and the like, and the recording medium P after image formation is placed on the paper ejection tray 31.

[Ink supply unit]
The ink supply unit 40 has a main tank 41 (see FIG. 3) for storing ink, and supplies ink of each color to the head unit 24 of the image forming unit 20. The ink supplied to the head unit 24 of the image forming unit 20 is ejected from the respective nozzles 52 of the inkjet head 50.

The ink used in the inkjet recording apparatus 1 in the present embodiment is, for example, an ultraviolet (UV) curable ink. This UV curable ink undergoes a phase change between a gel state and a liquid (sol) state depending on the temperature in a state where UV is not irradiated. This ink has, for example, a phase change temperature of about 40 ° C. to 100 ° C., and is uniformly liquefied (solized) by being heated and raised above this phase change temperature. On the other hand, this ink gels at a predetermined temperature or lower including about normal room temperature (0 ° C. to 30 ° C.).

1-2. Ink Discharge Mechanism Next, an ink ejection mechanism that is supplied from the ink supply unit 40 to the head unit 24 and ejected from the inkjet head 50 will be described. Here, the ink ejection mechanism refers to a mechanism related to an operation of supplying ink from the ink supply unit 40 to the head unit 24 and ejecting ink from a plurality of nozzles 52 of the inkjet head 50. FIG. 3 is a configuration diagram showing an ink ejection mechanism including an ink supply unit 40 and a head unit 24. In FIG. 3, the parts corresponding to FIG. 1 are designated by the same reference numerals, and duplicate description will be omitted.

The ink ejection mechanism includes a main tank 41, a first sub tank 64 (the ink tank of the present invention), a degassing device 80, a second sub tank 65, and an inkjet head 50. Further, the ink ejection mechanism includes a first piping section 90, a second piping section 91, a third piping section 93, a fourth piping section 95, and a first sub tank, which serve as ink supply paths for supplying ink to the ink jet head 50. 64 includes a fifth piping unit 94 and a sixth piping unit 96, which serve as ink discharge paths for discharging ink.

[Main tank]
The main tank 41 stores the ink distributed in each part of the ink ejection mechanism, and supplies the stored ink to the first sub tank 64. In the main tank 41, the ink is held at substantially room temperature (room temperature), and the ink at room temperature is supplied from the main tank 41 to the first sub tank 64.

[1st sub tank]
The first sub-tank 64 stores the ink supplied from the main tank 41, and the stored ink is heated to a liquefaction temperature by a heating unit (not shown) provided in the first sub-tank 64. The heating unit is composed of a heater, a heat transfer member that transfers heat from the heater, and the like, and heats and keeps the temperature of the ink in the first sub tank 64 to a predetermined temperature. As the heater, for example, a heating wire that generates Joule heat when energized is used. Further, as the heat transfer member, a member having a high thermal conductivity, for example, a heat conductive plate made of various metals (alloys) is used. The first sub-tank 64 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. Further, the first sub-tank 64 is provided with the first liquid level sensor 64a, and the amount of ink stored in the tank can be constantly detected.

[Degassing device]
The degassing device 80 includes a degassing unit 81, a dispersion plate 82, a dispersion plate drive unit 83, and a pressure control unit 84. FIG. 4 is a schematic configuration diagram showing an enlarged degassing device 80. As shown in FIG. 4, the degassing portion 81 is a cylindrical side wall portion 87, a disk-shaped upper surface portion 85 provided so as to cover the upper end surface of the side wall portion 87, and a lower side portion 87 thereof. It has a bottom surface portion 86 provided so as to cover the end face. As will be described later, the inner wall surface 87a of the side wall portion 87 is a portion that flows down to the bottom surface portion 86 side along the inner wall surface 87a while holding the ink in a thin film form. It is configured to stand vertically.

A second piping portion 91, which will be described later, is connected to the central portion of the upper surface portion 85. From the second piping section 91, the ink supplied from the first sub tank 64 side is supplied to the inside of the degassing section 81. The bottom surface portion 86 is composed of a convex portion 86a provided so that a central portion partially protrudes toward the upper surface side, and an outer peripheral portion 86b connected to the lower end surface of the side wall portion 87 on the outer peripheral side of the convex portion 86a. ing. That is, in the present embodiment, in the degassing portion 81, the distance from the upper surface portion 85 to the outer peripheral portion 86b of the bottom surface portion 86 is configured to be longer than the distance from the upper surface portion 85 to the convex portion 86a of the bottom surface portion 86. Has been done. Further, a third piping portion 93 that supplies ink to the second sub tank 65 side is connected to a part of the outer peripheral portion 86b.

Further, the degassing portion 81 is provided with a lower sensor 81a, an intermediate sensor 81b, and an upper sensor 81c at predetermined intervals from the bottom surface portion 86 side to the upper surface portion 85 side of the inner wall surface 87a. These sensors 81a, 81b, and 81c are sensors that detect the liquid level of the ink stored in the degassing unit 81, respectively, and the liquid level is detected by each of the lower sensor 81a, the intermediate sensor 81b, and the upper sensor 81c. If so, the information is sent to the control unit 100 (see FIG. 5). The amount of ink stored in the degassing unit 81 can be changed at any time depending on the setting. The method of controlling the amount of storage in the degassing unit 81 will be described in detail later.

The dispersion plate 82 is composed of a disk-shaped dispersion plate main body 82a and a shaft portion 82b that connects the dispersion plate main body 82a to the dispersion plate drive unit 83. The dispersion plate main body 82a has an outer diameter smaller than the inner diameter of the side wall portion 87, and rotates around the shaft portion 82b. The shaft portion 82b is erected at the central portion of the convex portion 86a on the bottom surface portion 86, and is rotatably driven by the dispersion plate driving portion 83 provided on the outside of the degassing portion 81. In the shaft portion 82b, the dispersion plate main body 82a is located directly under the second piping portion 91, and the ink supplied from the second piping portion 91 flows down to the surface of the dispersion plate main body 82a. To support.

The dispersion plate drive unit 83 is provided outside the degassing unit 81, and rotationally drives the shaft portion 82b of the dispersion plate 82. The pressure control unit 84 communicates with the inside of the degassing unit 81 via the ventilation path 92. Under the control of the control unit 100, the pressure control unit 84 controls the pressure so that the inside of the degassing unit 81 becomes a vacuum. In the present embodiment, the ink supplied to the degassing section 81 is degassed (defoamed) inside the degassing section 81 and discharged to the third piping section 93 side. The degassing principle in the degassing device 80 will be described in detail later.

[Second sub tank]
The second sub-tank 65 stores ink supplied from the first sub-tank 64 via the degassing unit 81, and has a heating unit (not shown) for holding the stored ink at a predetermined temperature. Have. The configuration of the heating unit in the second sub tank 65 can be the same as that of the heating unit for heating the ink in the first sub tank 64. The second sub-tank 65 is a closed tank-shaped container except for various connection points. Therefore, the pressure in the second sub tank 65 changes depending on the degree of negative pressure applied by the pressure control unit (not shown), the presence or absence of ink supply from the first sub tank 64, and the like. Further, the second sub-tank 65 is provided with a second liquid level sensor 65a, and the amount of ink stored in the tank can be constantly detected.

In the present embodiment, the pressure from the second sub tank 65 to the inside of the inkjet head 50 is set to a negative pressure state by the pressure control unit (not shown), and ink is discharged from the nozzle 52 when image formation and various maintenances are not performed. It is prevented from leaking.

Although a detailed diagram is omitted, the inkjet recording apparatus 1 of the present embodiment has a configuration in which ink is supplied from one first sub-tank 64 to a plurality of four second sub-tanks 65 in the head unit 24. Further, each second sub-tank 65 is configured to supply ink to two inkjet heads 50.

[Inkjet head]
The inkjet head 50 communicates with an inlet 53 connected to the third piping section 93, an upper flow path section 44 and a lower flow path section 57, and a sixth piping section 96 that function as a flow path for ink discharged from the inkjet head 50. It has an outlet 55 and a head control unit 54.

The inlet 53 is composed of a tubular member, one end of which is connected to the fourth piping portion 95 and the other end of which is connected to the upper flow path portion 44. Both ends of the inlet 53 are open and communicate with the upper flow path portion 44. As a result, the ink flowing from the third piping portion 93 flows to the upper flow path portion 44 side via the inlet 53.

The upper flow path portion 44 and the lower flow path portion 57 each have a flow path inside which guides ink to be supplied to each of the plurality of nozzles 52 of the inkjet head 50. The flow path is a common flow path shared by the plurality of nozzles 52, and guides the ink flowing through the inlet 53. That is, the ink supplied from the inlet 53 flows through the upper flow path portion 44 and the lower flow path portion 57 and reaches the plurality of nozzles 52.

Further, a filter 56 is provided between the upper flow path portion 44 and the lower flow path portion 57. As a result, the ink flowing from the upper flow path portion 44 to the lower flow path portion 57 is filtered by the filter 56, and the ink in a state in which impurities are removed can be supplied to the nozzle 52 side.

A pressure chamber 59 is provided near the nozzle 52 surface below the lower flow path portion 57. Under the control of the control unit 100, the pressure chamber 59 applies pressure to the nozzle 52 corresponding to the ink ejected according to the image formed on the recording medium P, and ejects the ink.

The outlet 55 is provided on the side opposite to the position where the inlet 53 is provided so as to sandwich the area where the nozzle 52 is provided. Like the inlet 53, the outlet 55 is composed of a tubular member, one end of which is connected to the sixth piping portion 96 and the other end of which is connected to the upper flow path portion 44. Both ends of the outlet 55 are opened, and communicate with the sixth piping portion 96 and the upper flow path portion 44. As a result, the ink that has flowed from the upper flow path portion 44 without being ejected from the nozzle 52 is discharged to the sixth piping portion 96 side via the outlet 55.

The head control unit 54 is provided above, for example, the upper flow path unit 44, and controls the operation of the pressure chamber 59 under the control of the control unit 100.

[1st piping section]
The first piping portion 90 is composed of a tubular member that serves as an ink flow path, connects the main tank 41 and the first sub tank 64, and communicates the inside of the main tank 41 and the inside of the first sub tank 64. A first pump 66 is provided in the first piping portion 90. The first pump 66 supplies ink from the main tank 41 to the first sub tank 64 under the control of the control unit 100. As the first pump 66, a positive displacement pump such as a diaphragm pump or a tube pump is used.

[Second piping section]
The second piping portion 91 is composed of a tubular member that serves as an ink flow path, and one end thereof is connected to the first sub tank 64 and the other end is connected to the upper surface portion 85 of the degassing portion 81. The inside of the sub tank 64 and the inside of the degassing unit 81 are communicated with each other. As the second piping portion 91, for example, a tube made of a resin material having good heat transfer properties is used. A filter 67, a flow rate limiting unit 68, and a first solenoid valve 69 are provided on the flow path of the second piping unit 91 from the first sub tank 64 side to the degassing unit 81 side. The filter 67 is arranged on the upstream side of the flow rate limiting unit 68 and the first solenoid valve 69 in the ink supply direction. The flow rate limiting unit 68 is arranged on the upstream side of the first solenoid valve 69 in the ink supply direction.

The filter 67 is a member that removes foreign matter from the ink flowing through the second piping portion 91, and is provided on the upstream side of the flow rate limiting portion 68 and the first solenoid valve 69 with respect to the direction in which the ink flows, so that the degassing portion It is possible to prevent foreign matter from being mixed into 81. The flow rate limiting unit 68 is composed of a member capable of adjusting the flow rate of ink flowing from the first sub tank 64 side to the degassing unit 81 side, and can be composed of, for example, a speed controller.

By the way, while the first sub-tank 64 is open to atmospheric pressure, the degassing section 81 is maintained in a vacuum, so that the first sub-tank 64 and the degassing section 81 connected by the second piping section 91 are connected to each other. There is a pressure difference between them. Therefore, when the flow rate is controlled only by the first solenoid valve 69 without providing the flow rate limiting unit 68, the ink on the first sub tank 64 side flows into the degassing unit 81 side at once, and the degree of vacuum inside the degassing unit 81 is increased. The problem arises that deaeration is not performed properly. Further, when the degree of vacuum is increased in order to improve the degassing accuracy in the degassing portion 81, the first solenoid valve 69 may be destroyed by the pressure difference between the first sub tank 64 and the degassing portion 81.

On the other hand, in the present embodiment, since the flow rate limiting unit 68 can limit the flow rate of the ink flowing to the degassing unit 81 side, it is possible to prevent the ink from suddenly flowing into the degassing unit 81.

Under the control of the control unit 100, the first solenoid valve 69 opens and closes the flow path of the second piping unit 91 between the flow rate limiting unit 68 and the degassing unit 81. When the first solenoid valve 69 is opened, ink limited to a predetermined amount by the flow rate limiting unit 68 is supplied from the first sub tank 64 to the degassing unit 81 side. On the other hand, when the first solenoid valve 69 is closed, the supply of ink from the first sub tank 64 to the degassing portion 81 is stopped.

In this embodiment, the flow rate limiting unit 68 is arranged on the upstream side and the first solenoid valve 69 is arranged on the downstream side in the ink supply direction. However, the flow rate limiting unit 68 and the first solenoid valve 69 are used. The arrangement with and may be reversed. That is, in the ink supply direction, the first solenoid valve 69 may be arranged on the upstream side, and the flow rate limiting unit 68 may be arranged on the downstream side.

In the present embodiment, for example, the control unit 100 can control the flow rate limiting unit 68 according to the amount of ink ejected from the inkjet head 50. Further, in the present embodiment, a detector for detecting clogging of the filter 67 may be provided in the vicinity of the filter 67, and the flow rate limiting unit 68 may be controlled according to the state of the filter 67. For example, this detector can be configured to detect a change in the flow velocity of the ink that has passed through the filter 67 to detect the state of the filter 67. In addition, the first liquid level sensor 64a of the first sub-tank 64 can detect the clogging of the filter 67 by detecting the change in the amount of ink stored in the first sub-tank 64.

Further, in the present embodiment, the speed controller is used as the flow rate limiting unit 68, but in addition to this, a pump capable of supplying a predetermined amount of ink can be used.

[Third piping section]
The third piping portion 93 is composed of a tubular member that serves as an ink flow path, one end of which is connected to an outer peripheral portion 86b constituting the bottom surface portion 86 of the degassing portion 81, and the other end of which is connected to the second sub tank 65. It is connected and communicates with the inside of the degassing unit 81 and the inside of the second sub tank 65. As the third piping portion 93, for example, a tube made of a resin material having good heat transfer properties is used. Further, the third piping portion 93 is provided with a second pump 70 and a second solenoid valve 71. The second pump 70 supplies ink from the degassing unit 81 to the second sub tank 65 side under the control of the control unit 100. As the second pump 70, a positive displacement pump such as a diaphragm pump or the like is used.

Under the control of the control unit 100, the second solenoid valve 71 opens and closes the flow path of the third piping unit 93 between the degassing unit 81 and the second sub tank 65. When the second solenoid valve 71 is opened, the ink discharged from the degassing unit 81 via the second pump 70 is supplied to the second sub tank 65. On the other hand, when the second solenoid valve 71 is closed, the ink discharged from the degassing unit 81 via the second pump 70 is discharged to the first sub tank 64 side.

[4th piping section]
The fourth piping portion 95 is composed of a tubular member that serves as an ink flow path, one end of which is connected to the second sub tank 65, and the other end of which is connected to the inlet 53 of the inkjet head 50. The inside of 65 and the inlet 53 are communicated with each other. As the fourth piping portion 95, for example, a tube made of a resin material having good heat transfer properties is used. The ink supplied from the fourth piping portion 95 to the inlet 53 is ejected from the nozzle 52 via the upper flow path portion 44 and the lower flow path portion 57 of the inkjet head 50.

[Fifth piping section]
The fifth piping section 94 is composed of a tubular member that serves as an ink flow path, and one end of the fifth piping section 94 is connected between the second pump 70 and the second solenoid valve 71 provided on the flow path of the third piping section 93. The other end is connected to the first sub tank 64. That is, the fifth piping section 94 communicates the degassing section 81 with the first sub tank 64 via the third piping section 93. As the fifth piping portion 94, for example, a tube made of a resin material having good heat transfer properties is used. Further, the fifth piping section 94 is provided with a check valve 72 that allows only ink to be discharged from the degassing section 81 side to the first sub tank 64 side.

In the present embodiment, while the second pump 70 is turned on in the third piping section 93, the second solenoid valve 71 is closed, and the ink discharged from the degassing section 81 is not supplied to the second sub tank 65 side. The ink discharged from the degassing unit 81 is discharged to the first sub tank 64 side via the check valve 72. As a result, the ink degassed by the degassing unit 81 can be returned to the first sub tank 64 side. Therefore, while the ink is not supplied from the degassing unit 81 to the second sub tank 65 side, the degree of ink degassing can be further improved by circulating the ink between the degassing unit 81 and the first sub tank 64. it can.

[6th piping section]
The sixth piping portion 96 is composed of a tube-shaped member that serves as an ink flow path, connects the outlet 55 of the inkjet head 50 and the first sub tank 64, and communicates the inkjet head 50 and the inside of the first sub tank 64. To do. As the sixth piping portion 96, for example, a tube made of a resin material having good heat transfer properties is used. A third solenoid valve 73 is provided on the flow path of the sixth piping portion 96. The third solenoid valve 73 opens and closes the flow path of the sixth piping section 96 between the outlet 55 and the first sub tank 64 under the control of the control section 100. By the sixth piping unit 96, the ink remaining without being ejected from the inkjet head 50 can be collected in the first sub tank 64.

1-3. Degassing Principle Here, the degassing principle in the degassing device 80 used in the ink ejection mechanism of the present embodiment will be described. First, in the degassing device 80, the inside of the degassing unit 81 is held at a predetermined degree of vacuum by the pressure control unit 84 under the control of the control unit 100. In this state, the ink I whose flow rate is limited by the flow rate limiting unit 68 provided in the second piping unit 91 flows into the degassing unit 81. Then, the ink I that has flowed into the degassing portion 81 is supplied to the central portion of the dispersion plate main body 82a as shown in FIG. At this time, the bubbles in the ink I are expanded and released under vacuum. Further, since the dispersion plate main body 82a is rotating, the ink I supplied to the surface of the dispersion plate main body 82a due to the centrifugal force spreads toward the outer periphery of the dispersion plate main body 82a, becomes thin, and further bubbles. Is released.

Next, the ink I that has reached the outer edge of the dispersion plate main body 82a due to the centrifugal force of the dispersion plate main body 82a is dispersed in the outer radius of the dispersion plate main body 82a and adheres to the inner wall surface 87a of the degassing portion 81. It spreads like a thin film on the inner wall surface 87a. Then, the ink adhered to the inner wall surface 87a of the degassing portion 81 in the form of a thin film drips toward the bottom surface portion 86 due to gravity. Then, in the process of the ink I dripping on the inner wall surface 87a, the gas and air bubbles inside the ink I are further released, and the degassed ink I is stored on the bottom surface 86 side of the degassing portion 81. The ink I having a high degree of degassing that has hung down on the bottom surface 86 side of the degassing portion 81 is discharged to the second sub tank 65 side or the first sub tank 64 side via the third piping portion 93.

In the degassing device 80 of the present embodiment, the ink I travels along the inner wall surface 87a of the degassing portion 81 and drips from the surface of the thinned ink I to the bottom surface portion 86 side of the degassing portion 81. Degassing is achieved by releasing gases and bubbles under vacuum. Therefore, on the inner wall surface 87a of the degassing portion 81, the larger the section H in which the ink I can be maintained in a thin film shape, the higher the degree of degassing. For example, when the degassing unit 81 is configured so that the ink I can be stored up to the upper sensor 81c, the section H shown in FIG. 4 is a section in which the ink I is degassed on the inner wall surface 87a. The section H to be degassed on the inner wall surface 87a is preferably determined according to the required degree of degassing.

In the present embodiment, by forming the bottom surface 86 into a convex shape, the inner wall surface 87a to which the ink is attached can be lengthened with respect to the position where the dispersion plate 82 is attached, so that the degree of degassing can be increased. .. Further, in the present embodiment, the dispersion plate 82 is erected on the bottom surface portion 86 side, but it may be attached from the top surface portion 85 side. In this case, since the dispersion plate 82 does not need to be attached to the bottom surface portion 86 side, the bottom surface portion 86 may be formed of a flat member.

1-4. Configuration of Control System Next, the internal configuration of the inkjet recording device 1 of the present embodiment will be described. FIG. 5 is a block diagram of the control system of the inkjet recording device 1.

As shown in FIG. 5, the control unit 100 of the inkjet recording device 1 is connected to the paper feeding unit 10, the paper ejection unit 30, and the image forming unit 20 via the system bus 120, respectively. Further, the control unit 100 includes a first pump 66, a second pump 70, a first solenoid valve 69, a second solenoid valve 71, a third solenoid valve 73, a pressure control unit 84, and a dispersion plate drive unit. The 83, the flow rate limiting unit 68, the lower sensor 81a, the intermediate sensor 81b, the upper sensor 81c, the first liquid level sensor 64a, and the second liquid level sensor 65a are connected via the system bus 120, respectively. Has been done. Then, the control unit 100 controls the entire system constituting the inkjet recording device 1.

The control unit 100 includes, for example, a CPU (Central ProceSSing Unit) 101, a ROM (Read Only Memory) 103 for storing programs executed by the CPU 101, and a RAM (Random AcceSS Memory) 102 used as a work area of the CPU 101. And have. As the ROM 103, a programmable ROM that can be electrically erased is usually used.

Image data transmitted from, for example, a personal computer (not shown), which is an external device connected to the image forming unit 20, is sent to the image processing unit 28 and image-processed by the image processing unit 28. Under the control of the control unit 100, the image processing unit 28 performs image processing such as shading correction, image density adjustment, and image compression on the received image data, if necessary. Further, each unit of the image forming unit 20 forms an image on the recording medium P sent from the paper feeding unit 10 based on the image data image-processed by the image processing unit 28 under the control of the control unit 100. ..

Further, the image of the recording medium P discharged to the delivery unit 26 of the image forming unit 20 is detected by the image reading sensor 27, and the image data is sent to the control unit 100.

By the way, in the conventional inkjet recording apparatus, a degassing module using a hollow fiber membrane is used in the degassing part. In a configuration in which ink is passed through the hollow fiber membrane and the outside of the hollow fiber membrane is held in a vacuum to degas bubbles and gases in the ink, the flow path resistance in the hollow fiber membrane becomes high. Therefore, even if there is a pressure difference between the degassing module using the hollow fiber membrane and the tank that supplies ink to the degassing module, the ink stored in the tank rapidly flows into the degassing module side. There is no such thing. On the contrary, when the degassing module using the hollow fiber membrane is used, the flow path resistance in the degassing module is high, so that a method of supplying ink from the tank using a liquid feeding pump is adopted.

On the other hand, when an attempt is made to supply ink into the tank-shaped degassing portion 81 which has no flow path resistance and is maintained in a vacuum as in the degassing device 80 of the present embodiment, the ink is supplied in the first sub tank 64. Ink may flow rapidly. Therefore, if the conventional degassing module is simply replaced with the degassing device 80 of the present embodiment, there is a problem that degassing cannot be performed normally when an attempt is made to use it in-line.

Therefore, in the present embodiment, by providing the flow rate limiting unit 68 between the first sub tank 64 and the degassing unit 81, the ink stored in the first sub tank 64 is degassed from the first sub tank 64. Due to the pressure difference from the unit 81, it is possible to prevent the air from being suddenly supplied to the degassing unit 81 side.

In the degassing device 80 of the present embodiment, the gas and air bubbles contained in the ink can be removed by allowing the ink to flow down in a thin film on the inner wall surface 87a of the degassing portion 81 maintained in a vacuum. Therefore, unlike the degassing module using the hollow fiber membrane, good degassing performance can be maintained without clogging the ink flow path.

Further, in the conventional degassing module using a hollow fiber membrane, when highly viscous gel ink is used, there is a problem that the ink does not flow into the degassing module due to the flow path resistance. On the other hand, in the present embodiment, since the ink may be supplied to the tank-shaped degassing portion 81 and adhered to the inner wall surface 87a in the form of a thin film, the viscosity of the degassable ink has a certain range. Can be made. Further, according to the degassing device 80 of the present embodiment, the cost can be reduced as compared with the degassing module using the hollow fiber membrane.

Further, in the present embodiment, the flow rate limiting unit 68 can be controlled by the control unit 100 according to the amount of ink stored in the degassing unit 81. The control method will be described below.

1-5. Control method of inkjet recording device (control example of flow rate limiting unit)
FIG. 6 is a flowchart showing a control method of the flow rate limiting unit 68 in the inkjet recording device 1 of the present embodiment. In the following, in the inkjet recording apparatus 1 of the present embodiment, the amount of ink stored in the degassing unit 81 is detected, and an appropriate amount of ink is supplied to the degassing unit 81 side by the flow rate limiting unit 68. A method of adjusting the flow rate limiting unit 68 will be described. The control step of the flow rate limiting unit 68 shown in FIG. 6 is a control step of operating the flow rate limiting unit 68 before the printing operation (for example, when the machine is started up).

As shown in FIG. 6, first, the control unit 100 detects whether or not the lower sensor 81a of the degassing unit 81 is in the off state (step S1). That is, in step S1, it is detected whether or not ink is stored up to the position of the lower sensor 81a of the degassing unit 81. In the case of "NO" in step S1, that is, when the ink is stored up to the position of the lower sensor 81a of the degassing unit 81 and the lower sensor 81a is in the ON state, the second pump 70 is turned on. The ink in the degassing section 81 is discharged to the first sub tank 64 via the piping section 94.

On the other hand, if "YES" in step S1, that is, if ink is not stored up to the position of the lower sensor 81a of the degassing unit 81 and the lower sensor 81a is in the off state, the second pump is turned off. (Step S3). That is, in step S1 and step S2,
The second pump 70 is driven until the lower sensor 81a is turned off to lower the liquid level in the degassing portion 81. In the control step shown in FIG. 6, it is assumed that the inside of the degassing unit 81 is held in a vacuum by the pressure control unit 84.

Next, the control unit 100 drives the dispersion plate drive unit 83 and starts the rotation of the dispersion plate 82 (step S4). After that, the control unit 100 opens the first solenoid valve 69 and supplies ink from the first sub tank 64 side into the degassing unit 81 (step S5).

After that, the control unit 100 detects whether or not the lower sensor 81a of the degassing unit 81 is in the ON state (step S6). In the case of "NO" in step S6, that is, when the ink is not stored up to the position of the lower sensor 81a of the degassing unit 81 and the lower sensor 81a is in the off state, the process returns to step S6.

On the other hand, in the case of "YES" in step S5, that is, when the ink is stored up to the position of the lower sensor 81a of the degassing unit 81 and the lower sensor 81a is in the ON state, the control unit 100 sets the control unit 100. Time counting is started (step S7).

Next, the control unit 100 detects whether or not the intermediate sensor 81b of the degassing unit 81 is in the ON state (step S8). In the case of "NO" in step S7, that is, when the ink is not stored up to the position of the intermediate sensor 81b of the degassing unit 81 and the intermediate sensor 81b is in the off state, the control unit 100 counts the time. Then, the process returns to step S8.

On the other hand, when "YES" in step S8, that is, when the ink is stored up to the position of the intermediate sensor 81b of the degassing portion 81 and the intermediate sensor 81b is in the ON state, the first solenoid valve 69 is closed. (Step S9). After that, the control unit 100 stops the time count (step S10).

Next, the control unit 100 detects whether or not the time from when the lower sensor 81a of the degassing unit 81 is turned on until the intermediate sensor 81b is turned on is within a predetermined time range (step S11). If "YES" in step S11, that is, if the time from when the lower sensor 81a is turned on to when the intermediate sensor 81b is turned on is within a predetermined time, the flow rate limiting unit 68 ends without adjustment. To do.

On the other hand, in the case of "NO" in step S9, that is, when the time from when the lower sensor 81a is turned on to when the intermediate sensor 81b is turned on is not within a predetermined time, the control unit 100 is the flow rate limiting unit 68. Is adjusted (step S12). Here, the control unit 100 is a control table (illustrated) stored in the ROM 103 of the control unit 100 in advance so that the time from when the lower sensor 81a is turned on to when the intermediate sensor 81b is turned on is within a predetermined time. The flow rate limiting unit 68 is adjusted with reference to (omitted).

When the flow rate limiting unit 68 is adjusted in step S12, the process returns to step S1 and the controls from step S1 to step S11 are performed again.

In the present embodiment, the amount of ink supplied to the degassing unit 81 per unit time can be detected by the lower sensor 81a and the intermediate sensor 81b. Therefore, for example, it is necessary to provide a flow meter or the like in the second piping unit 91. There is no. Further, in the present embodiment, since the flow rate limiting unit 68 can be adjusted according to the amount of ink stored in the degassing unit 81, for example, degassing is performed according to the amount of ink discharged to the second sub tank 65 side. The flow rate of the ink charged into the unit 81 can be adjusted.

The flow rate of the ink injected into the degassing unit 81 must be larger than the flow rate of the ink ejected from the inkjet head 50. However, if the flow rate of the ink charged into the degassing unit 81 is too large, there arises a problem that the degassing performance is lowered. On the other hand, by using the control method of the flow rate limiting unit 69 in the present embodiment, the amount of ink stored in the degassing unit 81 can be kept below the position of the intermediate sensor 81b. Therefore, the section H to be degassed can be maintained on the inner wall surface 87a of the degassing portion 81, and the degassing performance can be maintained.

Further, if the filter 67 arranged on the upstream side of the flow rate limiting unit 68 with respect to the ink supply direction is clogged, there is a concern that the ink flow rate may drop. Against this, by adjusting the flow rate limiting unit 68 shown in FIG. 6, the ink flow rate charged into the degassing unit 81 can be appropriately maintained without being affected by the clogging of the filter 67. it can.

The upper sensor 81c is set to a height in the degassing section 81 where the degree of degassing cannot be guaranteed. For example, if the ink has reached the upper sensor 81c in the stage before step S1, the system An error will occur. When the upper sensor 81c is turned on, the work of supplying ink to the second sub tank 65 side and discharging the ink from the inkjet head 50 is performed.

1-6. Control method of inkjet recording device (Example of control of degassing device when ink is always stored in the degassing part)
Next, in the inkjet recording device 1 of the present embodiment, a control method of the degassing device 80 when ink is always stored in the degassing unit 81 will be described.

FIG. 7 is a flowchart showing a control method of the degassing device 80 of the inkjet recording device 1 according to the present embodiment. In the present embodiment, the control method of the degassing device 80 in the case where the ink is always stored in the degassing unit 81 in the inkjet recording device 1 is shown. The control of the degassing device 80 described below is repeated during normal printing.

First, the control unit 100 detects whether or not the lower sensor 81a of the degassing unit is in the ON state (step S31). If "YES" in step S31, that is, if the ink is stored up to the position of the lower sensor 81a of the degassing unit 81 and the lower sensor 81a is in the ON state, the process returns to step S11 again. In the control step shown in FIG. 7, it is assumed that the inside of the degassing unit 81 is held in a vacuum by the pressure control unit 84.

On the other hand, in the case of "NO" in step S31, that is, when the ink is not stored up to the position of the lower sensor 81a of the degassing unit 81 and the lower sensor 81a is in the off state, the control unit 100 The dispersion plate drive unit 83 is driven to start the rotation of the dispersion plate 82 (step S32). After that, the control unit 100 opens the first solenoid valve 69 and supplies ink from the first sub tank 64 side into the degassing unit 81 (step S33).

Although detailed description is omitted, when the flowchart shown in FIG. 7 is repeated in the degassing device 80, the degassing unit 81 to the degassing unit 81 at a predetermined timing corresponding to the ink ejection work from the inkjet head 50. 2 Ink is supplied to the sub tank 65 side. Therefore, the state of step S31 is constantly changing, and in step S31, the control unit 100 detects this change and controls the amount of storage in the degassing unit 81. The control related to the supply of ink from the degassing unit 81 to the second sub tank 65 side is independent of the control shown in FIG. 7.

Next, the control unit 100 detects whether or not the lower sensor 81a of the degassing unit 81 is in the ON state (step S34). In the case of "NO" in step S34, that is, when the ink is not stored up to the position of the lower sensor 81a of the degassing unit 81 and the lower sensor 81a is in the off state, the process returns to step S34.

On the other hand, in the case of "YES" in step S34, that is, when the ink is stored up to the position of the lower sensor 81a of the degassing unit 81 and the lower sensor 81a is in the ON state, the control unit 100 is the third. 1 The solenoid valve 69 is closed to stop the supply of ink to the degassing unit 81 (step S35). After that, the control unit 100 stops driving the dispersion plate drive unit 83 to stop the rotation of the dispersion plate 82 (step S36).

Then, in the present embodiment, the control unit 100 can hold the ink stored in the degassing unit 81 below the lower sensor 81a of the degassing unit 81 by repeating the operations of steps S31 to S36. it can.

In the present embodiment, even when the amount of ink supplied to the second sub tank 65 side changes or the amount of ink discharged to the first sub tank 64 side changes, the ink is stored inside the degassing unit 81. The amount of ink can be maintained below the lower sensor 81a.

2. Second embodiment (example of providing an intermediate tank between the deaerator and the second sub tank)
Next, the inkjet recording apparatus according to the second embodiment of the present invention will be described. The inkjet recording device of this embodiment is an example in which only the configuration of the degassing device is different from that of the first embodiment. Therefore, since the overall configuration of the inkjet recording device is the same as that in FIG. 1, the description thereof will be omitted. The ink ejection mechanism in the inkjet recording apparatus according to the present embodiment will be described below.

2-1. Ink ejection mechanism FIG. 8 is a schematic configuration diagram relating to an ink ejection mechanism of the inkjet recording apparatus of this embodiment. In FIG. 8, the same parts as those in FIG. 3 are designated by the same reference numerals, and duplicate description will be omitted.

The degassing device 180 according to the inkjet ejection mechanism of the present embodiment has an intermediate tank 181 in addition to the degassing unit 81 and the pressure control unit 84. The intermediate tank 181 is provided on the ink supply path between the degassing portion 81 and the second sub tank 65. Like the second sub-tank 65, the intermediate tank 181 is composed of a closed tank-shaped container except for various connection points, and the lower sensor 181a, which detects the liquid level at a predetermined interval from the bottom surface, An intermediate sensor 181b and an upper sensor 181c are provided. The lower sensor 181a, the intermediate sensor 181b, and the upper sensor 181c each detect the liquid level of the ink stored in the intermediate tank 181 and send the detected signal to the control unit 100 as necessary.

Further, the intermediate tank 181 is connected to the pressure control unit 84 via the air passage 99. The pressure control unit 84 is a pressure control unit 84 that controls the pressure of the degassing unit 81. Under the control of the control unit 100, the pressure inside the degassing unit 81 is controlled to a vacuum, and the inside of the intermediate tank 181 is controlled. The pressure of is also controlled to vacuum. As a result, the inside of the intermediate tank 181 is in a state of being controlled to the same pressure as the degassing portion 81.

Further, the ink ejection mechanism of the present embodiment has a third piping portion 93 provided between the degassing portion 81 and the intermediate tank 181 and a fifth piping provided between the degassing portion 81 and the first sub tank 64. A portion 98 and a seventh piping portion 97 provided between the intermediate tank 181 and the second sub tank 65 are provided.

[Third piping section]
The third piping portion 93 is composed of a tubular member that serves as an ink flow path, one end of which is connected to the outer peripheral portion 86b constituting the bottom surface portion 86 of the degassing portion 81, and the other end of which is connected to the intermediate tank 181. The inside of the degassing unit 81 and the inside of the intermediate tank 181 communicate with each other. As the third piping portion 93, for example, a tube made of a resin material having good heat transfer properties is used. A second pump 74 is provided on the flow path of the third piping section 93. The second pump 74 supplies ink from the degassing unit 81 to the intermediate tank 181 side under the control of the control unit 100. As the second pump 74, a positive displacement pump such as a diaphragm pump or the like is used.

[Fifth piping section]
The fifth piping portion 98 is composed of a tubular member that serves as an ink flow path, one end of which is connected to the outer peripheral portion 86b constituting the bottom surface portion 86 of the degassing portion 81, and the other end of which is connected to the first sub tank 64. The inside of the degassing unit 81 and the inside of the first sub tank 64 are communicated with each other. As the fifth piping portion 98, for example, a tube made of a resin material having good heat transfer properties is used. Further, on the flow path of the fifth piping portion 98, a third pump 75 and a check valve 72 are provided in this order from the degassing portion 81 side toward the first sub tank 64 side. Under the control of the control unit 100, the third pump 75 discharges ink from the degassing unit 81 to the first sub tank 64 side. The check valve 72 prevents backflow of ink from the first sub-tank 64 side to the degassing portion 81.

[7th piping section]
The seventh piping portion 97 is composed of a tubular member that serves as an ink flow path, one end of which is connected to the intermediate tank 181 and the other end of which is connected to the second sub tank 65, and the inside of the intermediate tank 181 and the second. It communicates with the inside of the sub tank 65. As the seventh piping portion 97, for example, a tube made of a resin material having good heat transfer properties is used. Further, a fourth pump 76 is provided on the flow path of the seventh piping portion 97. The fourth pump 76 supplies ink from the intermediate tank 181 side to the second sub tank 65 side under the control of the control unit 100.

With the above configuration, the ink supplied from the main tank 41 to the degassing section 81 via the first sub tank 64 is degassed in the degassing section 81 and inkjet via the intermediate tank 181 and the second sub tank 65. It is supplied to the head 50. Further, the ink that has been degassed in the degassing section 81 and has not been supplied to the intermediate tank 181 side is discharged to the first sub tank 64 side via the fifth piping section 98.

Further, in the inkjet recording apparatus of the present embodiment, the degassed ink is supplied to the intermediate tank 181 side by the second pump 74 at any time without storing the degassed ink inside the degassing unit 81. It is stored in the intermediate tank 181. As a result, a large section in which the ink is formed into a thin film can be taken inside the degassing portion 81, so that the degree of degassing can be increased. Further, in the present embodiment, the ink that is not stored in the intermediate tank 181 is discharged to the first sub tank 64 side via the third pump 75, so that the ink having a high degree of degassing is discharged to the first sub tank 64 and the degassing portion 81. It can be circulated between the ink and the ink, and the degree of degassing of the ink can be increased.

2-2. Configuration of Control System Next, the internal configuration of the inkjet recording device of the present embodiment will be described. FIG. 9 is a block diagram of the control system of the inkjet recording device 1. In FIG. 9, the parts corresponding to FIG. 5 are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 9, in the inkjet recording apparatus of the present embodiment, the control unit 100 is connected to the paper feeding unit 10, the paper ejection unit 30, and the image forming unit 20 via the system bus 120, respectively. ing. Further, the control unit 100 includes a first pump 66, a second pump 74, a third pump 75, a first electromagnetic valve 69, a third electromagnetic valve 73, a pressure control unit 84, and a dispersion plate drive unit 83. The flow limiting unit 68, the lower sensor 81a, the intermediate sensor 81b and the upper sensor 81c of the degassing unit 81, the lower sensor 181a, the intermediate sensor 181b and the upper sensor 181c of the intermediate tank 181 and the first liquid level sensor. The 64a and the second liquid level sensor 65a are each connected via the system bus 120. Then, the control unit 100 controls the entire system constituting the inkjet recording device.

Also in this embodiment, since the flow rate limiting unit 68 is provided between the first sub tank 64 and the degassing unit 81, ink is rapidly supplied into the degassing unit 81 from the first sub tank 64 side. Can be prevented. Further, in the inkjet recording apparatus of the present embodiment, the degassed ink is supplied to the intermediate tank 181 side by the second pump 74 at any time without storing the degassed ink inside the degassing unit 81. , Can be stored in the intermediate tank 181. By preventing the ink from being stored in the degassing portion 81 in this way, it is possible to take a large section in which the ink is formed into a thin film inside the degassing portion 81, so that the degree of degassing is high. can do.

Further, in the present embodiment, the control unit 100 can detect the amount of ink stored in the intermediate tank 181 by the lower sensor 181a, the intermediate sensor 181b, and the upper sensor 181c of the intermediate tank 181 as needed. Therefore, the control unit 100 controls the second pump 74 and the third pump 75 according to the amount of ink stored in the intermediate tank 181. If the ink is not stored in the intermediate tank 181 side, the control unit 100 controls the first sub tank 64 side. The degassed ink can be discharged.

2-3. Control Method of Inkjet Recording Device FIG. 10 is a flowchart showing a control method of the degassing device 180 according to the present embodiment. In the following, in the inkjet recording apparatus of the present embodiment, the ink is stored in the intermediate tank 181 without storing the ink inside the degassing unit 81, and the ink that is not stored in the intermediate tank 181 after degassing is constantly circulated. The control method of the degassing device 180 will be described. The control of the degassing device 180 described below is repeated during normal printing.

In the present embodiment, the dispersion plate 82 is rotationally driven, the first solenoid valve 69 is released, and the ink is always supplied into the degassing unit 81. First, the control unit 100 turns on the third pump 75 and discharges the ink degassed by the degassing unit 81 from the degassing unit 81 to the first sub tank 64 (step S21). Next, the control unit 100 determines whether or not the lower sensor 181a of the intermediate tank 181 is turned on (step S22). If "YES" in step S22, that is, if the ink is stored up to the position of the lower sensor 181a of the intermediate tank 181 and the lower sensor 181a is in the ON state, the process returns to step S21.

On the other hand, in the case of "NO" in step S22, that is, when the ink is not stored up to the position of the lower sensor 181a of the intermediate tank 181 and the lower sensor 181a is in the off state, the control unit 100 sets the control unit 100. The third pump 75 is turned off, the second pump 74 is turned on, and the ink degassed by the degassing section 81 is supplied from the degassing section 81 to the intermediate tank 181 side (step S23).

Next, the control unit 100 determines whether or not the lower sensor 181a of the intermediate tank 181 is turned on (step S24). In step S24, in the case of "NO", that is, when ink is not stored up to the lower sensor 181a of the intermediate tank 181 and the lower sensor 181a is in the off state, the control unit 100 performs step S24. Do it again.

On the other hand, in step S24, when "YES", that is, when the ink is stored up to the position of the lower sensor 181a of the intermediate tank 181 and the lower sensor 181a is in the ON state, the control unit 100 sets the control unit 100. The second pump 74 is turned off, and the supply of ink from the degassing unit 81 to the intermediate tank 181 side is stopped. Then, by repeating the control from step S21 to step S25, the ink storage charge in the intermediate tank 181 is always held below the lower sensor 181a, and the ink is degassed by the degassing unit 81, and the intermediate tank 181 is degassed. The ink that is not supplied to the side is discharged to the first sub tank 64 side and circulated.

When the control flow shown in FIG. 10 is repeated in the degassing device 180, ink is supplied from the intermediate tank 181 to the second sub tank 65 side by another control flow. Therefore, since the state of step S22 changes constantly, the control unit 100 detects this change and controls the amount of storage in the intermediate tank 181.

In the present embodiment, the degassed portion 81 is always degassed, and the ink that is not supplied to the intermediate tank 181 side is discharged to the first sub tank 64 side, so that the degassed ink can be circulated. The degree of degassing of ink can be improved.

Further, in the present embodiment, the ink is stored in the intermediate tank 181 and the ink is not stored in the degassing section 81, so that the section where the ink adheres in a thin film form is widened in the degassing section 81. Therefore, the degassing performance can be improved. In the present embodiment, the degassing unit 81 is also provided with the sensor, but when the intermediate tank 181 is used, the degassing unit 81 may not be provided with the sensor.

2-4. Modification Example Next, the ink ejection mechanism of the inkjet recording apparatus according to the modification of the present embodiment will be described. FIG. 11 is a schematic configuration diagram of an ink ejection mechanism according to a modified example. In FIG. 11, the parts corresponding to FIG. 10 are designated by the same reference numerals, and duplicate description will be omitted.

The ink ejection mechanism according to the modified example has a different ink supply path configuration from the third embodiment. As shown in FIG. 11, in the ink ejection mechanism according to the modified example, the ink supply path from the degassing section 81 to the intermediate tank 181 is composed of the third piping section 93, and the degassing section 81 to the first sub tank 64. The ink discharge path is composed of a fifth piping section 94 provided between the third piping section 93 and the first sub tank 64. The flow path between the degassing portion 81, the intermediate tank 181 and the first sub tank 64 of the present embodiment is the degassing portion 81, the first sub tank 64 and the second sub tank 65 of the ink ejection mechanism according to the first embodiment. It is the same as the flow path between and.

[Third piping section]
The third piping portion 93 is composed of a tubular member that serves as an ink flow path, one end of which is connected to the outer peripheral portion 86b constituting the bottom surface portion 86 of the degassing portion 81, and the other end of which is connected to the intermediate tank 181. The inside of the degassing unit 81 and the inside of the intermediate tank 181 communicate with each other. As the third piping portion 93, for example, a tube made of a resin material having good heat transfer properties is used. Further, the third piping portion 93 is provided with a second pump 70 and a second solenoid valve 71. The second pump 70 supplies ink from the degassing unit 81 to the intermediate tank 181 side under the control of the control unit 100. As the second pump 70, a positive displacement pump such as a diaphragm pump or the like is used. Under the control of the control unit 100, the second solenoid valve 71 opens and closes the flow path of the third piping unit 93 between the degassing unit 81 and the second sub tank 65. The third piping section 93 serves as an ink supply path for supplying the ink discharged from the degassing section 81 to the intermediate tank 181 side when the second pump 70 and the second solenoid valve 71 are on.

[Fifth piping section]
The fifth piping section 94 is composed of a tubular member that serves as an ink flow path, and one end of the fifth piping section 94 is connected between the second pump 70 and the second solenoid valve 71 provided on the flow path of the third piping section 93. The other end is connected to the first sub tank 64. That is, the fifth piping unit 94 communicates the third piping unit 93 with the first sub tank 64. As the fifth piping portion 94, for example, a tube made of a resin material having good heat transfer properties is used. Further, the fifth piping section 94 is provided with a check valve 72 that allows only ink to be discharged from the degassing section 81 side to the first sub tank 64 side. In the fifth piping section 94, when the second solenoid valve 71 is turned off and the second pump 70 is turned on, it serves as an ink discharge path for discharging the ink in the degassing section 81 to the first sub tank 64 side.

In the modified example, the second pump 74 and the third pump 75 were turned on / off in the third embodiment shown in FIG. 8, and the degassing portion 81 was degassed by opening and closing the second solenoid valve 71. It is possible to control whether the ink is supplied to the intermediate tank 181 side or discharged to the first sub tank 64 side. Therefore, by controlling the opening and closing of the second solenoid valve 71, the ink is stored in the intermediate tank 181 and the ink is circulated to the first sub tank 64 side by the same control as that shown in FIG. Can be done. Thereby, the same effect as that of the third embodiment can be obtained.

Although the present invention has been described above based on the embodiment, the present invention is not limited to the configuration described in the above-described embodiment, and the configuration can be appropriately changed without departing from the spirit of the present invention. It is a thing.

For example, in the present embodiment, the first sub-tank and the second sub-tank are provided on the flow path between the main tank and the inkjet head, but only the first sub-tank or the second sub-tank may be provided. Further, in the present embodiment, an example in which a gel-like ink is used has been described, but the present invention is not limited to this, and can be applied to an inkjet recording device using a liquid ink. That is, any ink that can be degassed by forming a thin film of ink in the degassing portion of the degassing device can be applied.

Further, in the above-described embodiment, the degassing portion 81 is formed of a cylindrical member, but may also have a conical shape, and holds the ink in a thin film shape and has a wall surface on the bottom surface side. Various changes can be made as long as the configuration allows the flow to flow along the above. Further, the inner wall surface may be formed, for example, in a corrugated shape or an uneven shape in order to increase the distance through which the ink flows.

Further, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. For example, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

1 ... Inkjet recording device, 10 ... Paper feeding unit, 20 ... Image forming unit, 27 ... Image reading sensor, 28 ... Image processing unit, 30 ... Paper ejection unit, 40 ... Ink supply unit, 41 ... Main tank, 50 ... Inkjet Head, 53 ... Inlet, 55 ... Outlet, 64 ... 1st sub tank, 65 ... 1st sub tank, 65 ... 2nd sub tank, 68 ... Flow limit part, 80 ... Degassing device, 81 ... Degassing part, 82 ... Dispersion plate , 83 ... Dispersion plate drive unit, 84 ... Pressure control unit, 87a ... Inner wall surface, 100 ... Control unit

Claims (10)

Ink tank where ink is stored and
An inkjet head that ejects ink supplied from the ink tank from a nozzle to form an image on a recording medium.
An degassing device provided on the ink supply path between the ink tank and the inkjet head to remove the gas dissolved in the ink supplied from the ink tank.
It is provided on the ink supply path between the ink tank and the degassing device, and is supplied to the degassing device so that the amount of ink supplied to the degassing device per unit time is within a predetermined range. A flow rate limiter that limits the flow rate of ink,
A control unit that controls the degassing device and the flow rate limiting unit is provided.
The degassing device is an inkjet recording device including a degassing unit that holds the supplied ink in a thin film form and a pressure control unit that can hold the inside of the degassing unit in a vacuum. The inkjet recording device according to claim 1, wherein the degassing device is provided in the degassing section and includes a dispersion plate that disperses ink supplied by being rotationally driven by centrifugal force. The inkjet recording device according to claim 1 or 2, wherein the flow rate limiting unit is composed of a speed controller. Claim 1 is provided on an ink supply path between the ink tank and the degassing portion, and a filter for removing foreign matter is provided on the upstream side of the flow rate limiting portion in the ink supply direction. The inkjet recording apparatus according to any one of 3 to 3. The inkjet recording apparatus according to any one of claims 1 to 4, wherein an on-off valve for operating the opening and closing of the flow path is provided on the ink supply path between the ink tank and the degassing portion. A pump for sending the ink degassed by the degassing section to the inkjet head side is provided on the ink supply path between the degassing section and the inkjet head. 5. The inkjet recording apparatus according to any one of 5. Any of claims 1 to 6, wherein an ink discharge path for discharging the ink degassed by the degassed portion to the ink tank side is provided between the degassed portion and the ink tank. The inkjet recording apparatus according to one item. The inkjet recording device according to any one of claims 1 to 7, wherein the degassing device includes an intermediate tank that holds the ink degassed in the degassing section in a vacuum. The inkjet recording according to any one of claims 1 to 8, wherein the ink supplied to the inkjet head is a gel-like ink that liquefies at a temperature equal to or higher than the liquefaction temperature and gels at a temperature lower than the liquefaction temperature. apparatus. Ink tank where ink is stored and
An inkjet head that ejects ink supplied from the ink tank from a nozzle to form an image on a recording medium.
An degassing device provided on the ink supply path between the ink tank and the inkjet head to remove the gas dissolved in the ink supplied from the ink tank.
It is provided on the ink supply path between the ink tank and the degassing device, and is supplied to the degassing device so that the amount of ink supplied to the degassing device per unit time is within a predetermined range. A flow rate limiter that limits the flow rate of ink,
A control unit that controls the degassing device and the flow rate limiting unit is provided.
The degassing device is a control method for an inkjet recording device including a degassing unit that holds the supplied ink in a thin film form and a pressure control unit that can hold the inside of the degassing unit in a vacuum. hand,
The control unit is a control method for an inkjet recording device that controls the flow rate limiting unit and limits the flow rate of ink supplied into the degassing unit.

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