Pressure fluctuation suppressing device and image forming apparatus

Abstract

To provide a pressure fluctuation suppressing device and an image forming device capable of predicting the breakage of a flexible film due to time degradation.SOLUTION: The inside of a housing 301 is divided into a first space 304 and a second space 305 by using a flexible film, and a spring 303 is arranged in the second space 305 to regulate the bending of the flexible film. The first space 304 communicates to a channel 209 of ink, and the flexible film bends according to the fluctuation of ink pressure to perform a damper function, while flatting when repeating the bending. A flexible film sensor 300 detects whether or not displacement amount due to bending of the flexible film in the second space reaches a displacement value (threshold value). Since the flexible film increases the displacement amount when the flatting progresses, the breakage of the flatting of the flexible film can be predicted by the flexible film sensor 300.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a pressure fluctuation suppressing device and an image forming apparatus, and more particularly to a technique for predicting damage due to deterioration over time of a flexible membrane in a pressure fluctuation suppressing device. [Background technology]

[0002] In recent years, inkjet printers, in which an inkjet head ejects ink from nozzles to form images on a recording medium, have been used in a wide range of fields. In order for an inkjet printer to eject ink at an appropriate ink speed and land the ink on a recording medium with good accuracy, the meniscus shape of the ink in the nozzle is important. As shown in Figure 10, a nozzle 1001 of an inkjet head 10 is open to the atmosphere, and a meniscus 1000 is the liquid surface shape of ink 1002 formed at the tip of the nozzle 1001.

[0003] However, in a scan-type inkjet printer, since the inkjet head is moved, acceleration is applied to the ink 1002, which may distort the shape of the meniscus 1000. Also, in a single-pass type inkjet printer, although the inkjet head is not moved, if acceleration is applied to the ink 1002 for some reason, the shape of the meniscus 1000 will still be distorted.

[0004] If the acceleration applied to the ink 1002 is particularly large, the meniscus shape may be destroyed, causing air to enter the nozzle 1012, resulting in ejection failure that makes it impossible to eject ink, or ink 1023 may leak from the nozzle 1022, causing image defects or soiling the inside of the inkjet printer.

[0005] To address this problem, for example, focusing on the fact that the meniscus 1000 is destroyed when acceleration is applied to the ink 1002 because the pressure of the ink 1002 at the nozzle 1001 fluctuates extremely, an image forming device is known in which a flexible film member (hereinafter referred to as a "flexible membrane") is arranged on the flow path of the ink 1002 from an ink tank that supplies the ink 1002 to the inkjet head to the nozzle 1001 (see Patent Document 1).

[0006] In this image forming apparatus, an ink container 11 as shown in Fig. 11 is provided on an ink flow path from an ink tank to a nozzle as a pressure fluctuation suppression device for suppressing pressure fluctuations in the ink, and the container 11 includes a flexible membrane 1101, a spring 1102, and a housing 1103. The housing 1103 has an ink inlet 1104 and an ink outlet 1105, and is further provided with an opening 1106. The flexible membrane 1101 is adhered and fixed to the housing 1103 so as to cover and close the opening 1106.

[0007] A spring 1102 is disposed inside the accommodating section 11 surrounded by the flexible membrane 1101 and the housing 1103. One end of the spring 1102 is erected at a position facing the flexible membrane 1101 of the housing 1103, and the other end is bonded to the flexible membrane 1101. The spring 1102 biases the flexible membrane 1101 outward from the accommodating section 11.

[0008] When the ink pressure in the flow path decreases, the flexible film 1103 deforms, changing the volume of the storage section 11, causing ink to flow out of the storage section 11. Conversely, when the ink pressure increases, the flexible film 1103 deforms, causing ink to flow into the storage section 11. By providing such a damper function, it is possible to suppress the pressure fluctuation of the ink in the flow path even when acceleration is applied to the ink, thereby reducing ejection defects and ink leakage caused by the inflow of air. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2012-250393 A [Patent Document 2] JP 2014-226811 A Summary of the Invention [Problem to be solved by the invention]

[0010] Inkjet printers can form images using a variety of inks. For example, UV (Ultra Violet) curable ink is an ink that uses a monomer that cures with ultraviolet light as a solvent, and has excellent properties such as being instantly fixed to a recording medium, but it must be heated before being ejected from a nozzle. For this reason, when the hot UV curable ink comes into contact with the flexible film 1103, the flexible film 1103 is also heated and increases in temperature. By repeating this process of increasing the temperature each time an image is formed, the flexible film 1103 gradually expands.

[0011] As a result, if the flexible membrane 1103, which is a pressure fluctuation suppression means for suppressing fluctuations in ink pressure, deteriorates over time, it may eventually break, causing ink to leak from the storage section 11 and causing problems such as soiling the inside of the inkjet printer or the recording medium.

[0012] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a pressure fluctuation suppressing device and an image forming apparatus that are capable of predicting damage to a pressure fluctuation suppressing means due to deterioration over time. [Means for solving the problem]

[0013] In order to achieve the above object, a pressure fluctuation suppression device according to one embodiment of the present disclosure includes a suppression means that is disposed in a liquid flow path and suppresses fluctuations in pressure of the liquid in the flow path, and a detection means that detects a decrease in the suppression function of the suppression means. The suppression means includes a flexible membrane that divides the inside and outside of the flow path, and the flexible membrane flexes when subjected to the pressure to suppress fluctuations in the pressure, and the detection means includes membrane displacement detection means that detects displacement of the flexible membrane and detects a decrease in the suppression function based on the magnitude of the displacement. It is characterized by:

[0014] In this case, the suppression means may include a flexible membrane that separates the inside and outside of the flow path, and the flexible membrane may bend under the pressure to suppress fluctuations in the pressure.

[0015] The flexible membrane may be stretched by repeatedly bending, and the detection means may detect the deterioration of the suppression function from the degree of stretching of the flexible membrane.

[0016] It is also preferable that the suppression means comprises a first space communicating with the flow path, and a second space partitioned from the first space by the flexible membrane.

[0017] The detection means may include a membrane displacement detection means for detecting a displacement of the flexible membrane, and may detect a decrease in the suppression function from the magnitude of the displacement.

[0018] The membrane displacement detection means may be disposed outside the flow channel.

[0019] In addition, the detection means may include a membrane displacement detection means for detecting a displacement of the flexible membrane, and detect a decline in the suppression function from the magnitude of the displacement, and the membrane displacement detection means may be disposed in the second space.

[0020] The membrane displacement detection means may be a contact sensor, and the detection means may determine the magnitude of the displacement based on whether or not the membrane displacement detection means detects contact with the flexible membrane.

[0021] The detection means may include pressure detection means for detecting pressure in the second space, and may detect a decrease in the suppression function from a response time of the pressure detected when the pressure varies.

[0022] The detection means may include a pressure adjustment means for adjusting the pressure in the second space, and may detect a decrease in the suppression function by varying the pressure using the pressure adjustment means.

[0023] In another aspect of the present disclosure, a liquid supply system includes: a suppression means that is disposed on a liquid flow path and suppresses fluctuations in pressure of the liquid in the flow path; and a detection means that detects a decrease in the suppression function of the suppression means. A pressure fluctuation suppression device comprising: The suppression means includes a flexible membrane that separates the inside and outside of the flow path, and the flexible membrane flexes when subjected to the pressure to suppress fluctuations in the pressure. The suppression means includes a first space that communicates with the flow path, and a second space that is separated from the first space by the flexible membrane. The detection means includes pressure detection means that detects the pressure in the second space, and pressure adjustment means that adjusts the pressure in the second space. The pressure is varied by the pressure adjustment means, and a decrease in the suppression function is detected from the response time of the pressure detected when the pressure varies. The pressure fluctuation suppression device includes a liquid storage section that is arranged upstream of the pressure adjustment means in the flow path, and a communication means that communicates the second space with the storage section. The pressure adjustment means forms a common negative pressure in the second space and the storage section.

[0024] The device may also include a notification unit that notifies an error when a deterioration in the suppression function is detected.

[0025] The notification means may further comprise a display means for displaying a warning notifying an error.

[0026] Furthermore, an image forming apparatus according to one embodiment of the present disclosure is an inkjet type image forming apparatus that forms an image by ejecting ink from a nozzle, and is characterized in that it is equipped with a pressure fluctuation suppression device described in any one of claims 1 to 13, the liquid is the ink, and the flow path is connected to the nozzle. Effect of the Invention

[0027] In this way, by detecting a deterioration in the suppression function of the suppression means, it is possible to estimate the extent to which the deterioration of the suppression means has progressed over time, and therefore it is possible to predict damage to the suppression means. [Brief description of the drawings]

[0028] [Figure 1] 1 is a diagram showing a main configuration of an image forming apparatus 1 according to a first embodiment of the present disclosure. [Diagram 2] 2 is a diagram showing a main configuration of an ink supply system 2 included in an image forming apparatus 1. FIG. [Diagram 3] 1A and 1B are diagrams showing the main components of the pressure fluctuation suppression device 200, in which (a) is a flexible membrane 302 before spreading, showing the flexible membrane 302 under normal ink pressure, (b) is a flexible membrane 302 after spreading, showing the flexible membrane 302 when the ink pressure is higher than normal, (c) is a flexible membrane 302 before spreading, showing the flexible membrane 302 when the ink pressure is lower than normal, and (d) is a flexible membrane 302 before spreading, showing the flexible membrane 302 when the ink pressure is higher than normal. [Figure 4] 2 is a block diagram showing the main components of a control unit 150. FIG. [Diagram 5] 13 is a flowchart illustrating a process in which the control unit 150 detects the extension of the flexible film 302. [Figure 6] 13A and 13B are diagrams showing the main components of a pressure fluctuation suppression device 200 according to a second embodiment of the present disclosure, in which (a) is a flexible membrane 302 before spreading, showing the flexible membrane 302 under normal ink pressure, and (b) is a flexible membrane 302 after spreading, showing the flexible membrane 302 when the ink pressure is higher than normal. [Figure 7] 13 is a diagram showing the main components of a pressure fluctuation suppression device 200 according to a third embodiment of the present disclosure, in which (a) is a flexible membrane 302 before spreading and shows the flexible membrane 302 under normal ink pressure, (b) is a flexible membrane 302 after spreading and shows the flexible membrane 302 when the ink pressure is higher than normal, and (c) is a graph comparing the change over time in air pressure in the second space 305 when the air pressure is adjusted for the flexible membrane 302 before and after spreading. [Figure 8] 13 is a diagram illustrating an example of a configuration for adjusting air pressure by communicating a second space 305 of the pressure fluctuation suppressing device 200 with a space above the ink liquid level in the subtank 207. FIG. [Figure 9]9 is a diagram showing a modified example in which the first space 304 of the pressure fluctuation suppressing device 200 and the flow path 209 communicate with each other through a single communication port 901. FIG. [Figure 10] 1A and 1B are diagrams illustrating problems that may occur when acceleration is applied to ink in a nozzle. [Figure 11] FIG. 1 is a diagram showing a main configuration of a pressure fluctuation suppressing device 11 according to a conventional technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a pressure fluctuation suppressing device and an image forming apparatus according to the present disclosure will be described with reference to the drawings. [1] First embodiment (1-1) Configuration of Image Forming Apparatus First, the configuration of the image forming apparatus according to the present embodiment will be described.

[0030] As shown in FIG. 1, an image forming apparatus 1 according to the present embodiment is a so-called inkjet printer, and includes a paper feed section 110, an image forming section 120, a paper discharge section 140, a control section 150, and an operation panel 160.

[0031] The paper feed unit 110 has a paper feed tray 111 and a conveying unit 112. The paper feed tray 111 is a tray for placing a stack of recording sheets S to be used for image formation. As the recording sheets S, various media capable of fixing ink that has landed on the surface, such as paper such as plain paper or coated paper, fabric or sheet-like resin, can be used.

[0032] The paper feed tray 111 moves up and down depending on the number of sheets in the sheet stack, and moves to a position where the topmost recording sheet S in the sheet stack is fed out by the conveying section 112 .

[0033] The conveying unit 112 uses a pickup roller (not shown) to feed the recording sheets S one by one from the top of the stack of sheets placed on the paper feed tray 111. The conveying unit 112 has a sheet conveying mechanism in which an endless conveying belt 114 is wound around rollers 113 and 115.

[0034] In the conveying unit 112, while the recording sheet S sent out by the pickup roller is placed on the conveying belt 114, the conveying unit 112 rotates and drives the rollers 113 and 115 to make the conveying belt 114 rotate in the direction of the arrow A, thereby conveying the recording sheet S to the image forming unit 120.

[0035] The image forming section 120 includes a transport drum 121, a delivery unit 122, a sheet heating section 123, a head unit 124, a fixing section 125, a delivery section 126, etc., and forms an image on a recording sheet S by an inkjet method.

[0036] The delivery unit 122 has a swing arm portion 127 and a delivery drum 128. The delivery unit 122 uses the swing arm portion 127 to hold one end of the recording sheet S conveyed by the conveying portion 112, and then picks up the recording sheet S and delivers the recording sheet S to the delivery drum 128.

[0037] The delivery drum 128 delivers the recording sheet S to the transport drum 121 by guiding the recording sheet S along the outer circumferential surface of the transport drum 121 .

[0038] When the transport drum 121 receives the recording sheet S from the delivery unit 122, the transport drum 121 transports the recording sheet S by being rotated in the direction of arrow B while carrying the recording sheet S on the outer circumferential surface of the cylindrical shape.

[0039] The conveying drum 121 may have, for example, an air intake hole on the outer peripheral surface, and may suck in outside air from the air intake hole to adsorb the recording sheet S onto the outer peripheral surface. Also, a claw for holding the edge of the recording sheet S may be provided on the outer peripheral surface.

[0040] The transport drum 121 is rotated by a transport drum rotation drive motor (not shown). During this rotation, the rotation angle of the transport drum 121 is adjusted so that the ink ejected from the inkjet head lands on a desired location on the recording sheet S.

[0041] The sheet heating section 123 heats the recording sheet S carried on the outer circumferential surface of the transport drum 121 on the transport path of the recording sheet S from the delivery unit 122 to the head unit 124 so that the temperature of the recording sheet S falls within a predetermined range.

[0042] For this reason, the sheet heating unit 123 is disposed opposite the outer circumferential surface of the conveying drum 121, and supplies power to an infrared heater or the like to radiate heat and raise the temperature of the recording sheet S. The temperature of the recording sheet S is adjusted to a predetermined range by controlling the amount of power supplied to the infrared heater or the like.

[0043] The head unit 124 is disposed downstream of the sheet heating unit 123 in the rotation direction of the transport drum 121. The head unit 124 includes a plurality of inkjet heads, and forms an image on the recording sheet S by ejecting ink from the nozzles of the inkjet heads in synchronization with the transport state of the recording sheet S by the transport drum 121.

[0044] The head unit 124 may be of a single-pass type in which nozzles are arranged across the entire effective image area of ​​the recording sheet S along the axial direction of the transport drum 121, or may be of a scan type in which nozzles are arranged on a carriage that moves back and forth along the axial direction of the transport drum 21, and ink is ejected while the carriage is moved.

[0045] When the scan method is adopted, the head transport mechanism that moves the carriage moves the nozzle surface of the inkjet head to a position (printing area) facing the outer circumferential surface of the transport drum 121 during image formation.

[0046] On the other hand, during maintenance or the like, the head transport mechanism may move the nozzle surface of the inkjet head to a position (maintenance area) facing a cleaning device (not shown) for cleaning.

[0047] In order to cause ink to land at an appropriate position on the recording sheet S, the head unit 124 is disposed at a position where the distance from the ink ejection surface of the inkjet head to the outer circumferential surface of the transport drum 121 is appropriate.

[0048] The head unit 124 is equipped with a pressure fluctuation suppressing device that suppresses fluctuations in the ink pressure within the ink flow path for transporting the ink to the nozzles.

[0049] In this embodiment, four colors of ink, yellow (Y), magenta (M), cyan (C) and black (K), are used to form a color image. For this reason, four head units 124 corresponding to the four colors of ink, YMCK, are disposed along the outer circumferential surface of the transport drum 121 in order from the upstream side to the downstream side in the rotation direction of the transport drum 121.

[0050] The fixing section 125 is disposed downstream of the head unit 124 in the rotation direction of the transport drum 121, and uses, for example, a mercury lamp to irradiate ultraviolet rays across the entire width of the recording sheet S in the main scanning direction, thereby hardening the ink that has landed on the recording sheet S and fixing it to the recording sheet S.

[0051] In addition, since the energy rays suitable for curing the ink differ depending on the characteristics of the ink, it is preferable to use an energy ray source suitable for the characteristics of the ink, not limited to a mercury lamp.

[0052] The delivery section 126 includes a sheet transport mechanism in which an endless belt 131 is wound around rollers 129 and 132, and a delivery drum 130. The delivery drum 130 is disposed so as to face the outer circumferential surface of the transport drum 121 downstream of the fixing section 125 in the rotation direction of the transport drum 121, and delivers the recording sheet S carried on the outer circumferential surface of the transport drum 121 to the sheet transport mechanism of the delivery section 126.

[0053] The sheet transport mechanism rotates rollers 129 and 132 to cause a belt 131 to travel in the direction of arrow C, and transports the recording sheet S received from a delivery drum 130 to a paper discharge unit 140.

[0054] The paper discharge unit 140 has a paper discharge tray 141, and sequentially stacks the recording sheets S transported from the image forming unit 120 by the delivery unit 126 on the paper discharge tray 141. The stack of recording sheets S stacked on the paper discharge tray 141 is then collected by the user.

[0055] The control unit 150 monitors and controls the state and operation of each part of the image forming apparatus 1. The control unit 150 also receives print jobs from external devices such as a personal computer (PC) and issues notifications related to the print jobs.

[0056] The operation panel 160 presents information to a user of the image forming apparatus 1 and receives instruction inputs from the user under the control of the control unit 150. For this reason, the operation panel 160 includes a display unit such as a liquid crystal panel, and an operation unit such as a touch panel or hard keys. (1-2) Ink supply system The image forming apparatus 1 includes an ink supply system that supplies ink to an inkjet head from an ink tank that stores ink used in an image forming process. As shown in Fig. 2, the ink supply system 2 includes a pressure fluctuation suppressing device 200, an ink tank 201, an inkjet head 211, and the like. In Fig. 2, the parts excluding the ink tank 201, the degassing device 204, and the pumps 206 and 215 constitute the head unit 124.

[0057] As described above, in this embodiment, the ink is gelled at room temperature and changes to liquid when heated, and in particular, energy ray irradiation type ink such as UV ink that solidifies when irradiated with energy rays is used. For this reason, the ink supply system 2 is also provided with a heater (not shown) for heating the ink to increase its temperature.

[0058] In Figure 2, an example is described in which the ink supply system 2 has a circulation flow path configuration, but it goes without saying that the present disclosure is not limited to the circulation flow path configuration, and other flow path configurations (see, for example, Patent Document 2) may be adopted.

[0059] The ink tank 201 stores ink 202 which is the liquid to be ejected from the inkjet head 211 .

[0060] When ink 202 is supplied from an ink tank 201 to an inkjet head 211, first, the ink 202 is sucked out of the ink tank 201 using a pump 206, and the ink 202 is sent to a degassing device 204 via a flow path 203. The degassing device 204 degasses the gas dissolved in the ink 202.

[0061] The ink 202 from which the dissolved gas has been degassed is sent to a subtank (hereinafter referred to as the "IN side subtank") 207 via a flow path 205. The IN side subtank 207 is for removing air bubbles that have become mixed into the flow path. An air pressure regulator 208 is connected to the IN side subtank 207, and the pressure of the air layer in the IN side subtank 207 is adjusted.

[0062] A filter 210 and a pressure fluctuation suppressing device 200 are disposed on a flow path 209 of the ink 202 that flows from the IN side sub-tank 207 toward the inkjet head 211 .

[0063] The filter 210 is provided to remove foreign matter contained in the ink 202, thereby preventing foreign matter from clogging the downstream portion of the filter 210 of the flow path 209 and the nozzle (not shown) of the inkjet head 211, etc.

[0064] The pressure fluctuation suppressing device 200 suppresses fluctuations in ink pressure when acceleration is applied to the ink 202 inside the nozzles of the inkjet head 211, thereby preventing air from entering the nozzles of the inkjet head 211 and ink from leaking out of the nozzles (FIG. 10). The inkjet head 211 ejects ink from the nozzles according to the image to be formed.

[0065] To eject ink from the nozzles, a pressure chamber (not shown) and a piezoelectric element (not shown) provided for each nozzle are used.

[0066] That is, the pressure chamber communicates with the nozzle, and ink is stored in the pressure chamber. The piezoelectric element forms the wall of the pressure chamber, and when a drive signal corresponding to an image signal is input, the piezoelectric element deforms, causing the ink stored in the pressure chamber to be ejected from the nozzle.

[0067] The ink 202 that has passed through the inkjet head 211 is sent to a subtank (hereinafter referred to as the "OUT-side subtank") 213 via a flow path 212. An air pressure adjusting device 214 is connected to the OUT-side subtank 213, and the pressure of the air layer in the OUT-side subtank 213 is adjusted.

[0068] Due to the difference in pressure between the air layer in the OUT-side sub-tank 213 and the air layer in the IN-side sub-tank 207, the ink 202 is sent from the IN-side sub-tank 207 to the OUT-side sub-tank 213. A pump 215 sends the ink 202 from the OUT-side sub-tank 213 to the ink tank 201 via a flow path 216.

[0069] In this way, it is possible to prevent problems caused by the ink 202 losing volatile components from the meniscus surface and increasing its viscosity, which could result in poor ejection of the ink 202, the components dispersed in the ink 202 that has accumulated in the flow path settling out and causing clogging, or the concentration of the ink 202 becoming non-uniform.

[0070] Needless to say, the location of the pressure fluctuation suppression device 200 is not limited to on the flow path 209 from the filter 210 to the inkjet head 211, but may be on the flow path 212 from the inkjet head 211 to the OUT side sub-tank 213, or at some other location.

[0071] However, in order to suppress the movement of the ink 202 in the vicinity of the nozzles of the inkjet head 211, it is more effective to dispose the pressure fluctuation suppressing device 200 at a location as close as possible to the nozzles. (1-3) Configuration of Pressure Fluctuation Suppressor 200 Next, the configuration of the pressure fluctuation suppressing device 200 will be described.

[0072] 3(a), the pressure fluctuation suppressing device 200 includes a housing 301, a flexible membrane 302a, and a spring 303. The inside of the housing 301 is divided into a first space 304 communicating with the flow path 209, and a second space 305 partitioned from the first space 304 by the flexible membrane 302.

[0073] In this embodiment, the housing 301 is described as having a rectangular parallelepiped shape as an example, but it goes without saying that the present disclosure is not limited to this, and instead of the rectangular parallelepiped shape, the housing 301 may have a shape other than a rectangular parallelepiped, such as a cylindrical shape.

[0074] Furthermore, in the case where the image forming apparatus 1 is equipped with a plurality of pressure fluctuation suppressing devices 200, the shapes of the housings 301 of the pressure fluctuation suppressing devices 200 may be different from each other.

[0075] The first space 304 has an inlet through which the ink flows in after passing through the filter 207, and an outlet through which the ink flows out toward the inkjet head 211. The first space 304 communicates with the flow path 209 via the inlet and outlet.

[0076] When no acceleration is applied to the ink in the nozzle, and therefore the pressure of the ink in the first space 304 is normal, the flexible membrane 302 is in a slack state.

[0077] The flexible film 302 may be made of a flexible material such as a resin film or a rubber film. It is preferable to select a material for the flexible film 302 that can bend appropriately according to the amount of ink pressure that may be applied to the flexible film 302.

[0078] When the flexible film 302 is fixed to the inner wall surface of the housing 301, it can be welded using heat or a laser, fixed by a mechanical process, or fixed with an agent such as an adhesive.

[0079] Also, the housing 301 may be divided into a first space 304 side and a second space 305 side at the position where the flexible film 302 is to be fixed, and these housings 301 may be fixed together with the flexible film 302 sandwiched between them.

[0080] In either case, it is preferable that the flexible membrane 302 has an appropriate amount of slack after it is fixed to the housing 301 .

[0081] In the second space 305, a base end of a spring 303 is fixed to an inner wall surface facing the flexible film 302a of the housing 301. A tip end of the spring 303 is fixed to the flexible film 302a. Since the first space 304 is in communication with the flow path 209, when the ink pressure in the flow path 209 fluctuates, the ink pressure in the first space 304 also fluctuates.

[0082] When flexible film 302a bends due to this pressure fluctuation, the fluctuation in the ink pressure in first space 304 and flow path 209 is suppressed. In other words, pressure fluctuation device 200 functions as a damper that suppresses the fluctuation in the ink pressure in flow path 209. By adopting such an arrangement, spring 303 is prevented from coming into contact with ink, so that corrosion, deterioration, and adhesion of ink due to contact with ink can be prevented.

[0083] The material of spring 303 may be metal, or may be a material other than metal, such as resin, etc. In addition, in this embodiment, a case where spring 303 is a coil spring will be described as an example, but it goes without saying that the present disclosure is not limited to this, and a spring other than a coil spring may be used.

[0084] Needless to say, an elastic member having an appropriate elastic coefficient other than a spring may be used. The appropriate elastic coefficient is an elastic coefficient that allows the flexible film 302a to be in a taut state without slack due to the biasing force (pressing force) of the elastic member (spring 303, etc.) when no ink has flowed into the first space 304, and allows the flexible film 302a to slacken when ink is stored in the first space 304 under normal ink pressure.

[0085] In this way, if the flexible membrane 302a is designed to sag appropriately under normal ink pressure, the flexible membrane 302a will flex when the ink pressure fluctuates, thereby changing the volume of the first space 304, thereby stably achieving the damper function of suppressing fluctuations in ink pressure.

[0086] The position where the tip of spring 303 is fixed is preferably the center of flexible film 302a, because this makes it possible to reduce unevenness in the tension applied to flexible film 302a.

[0087] Also, a spring may be disposed in the first space 304 as a supplement to the spring 303. However, in consideration of the effect of ink on the supplemental spring, it is preferable to provide the spring 303 only in the second space 305.

[0088] When the flexible membrane 302a is bent to the maximum extent, it cannot bend further from the maximum bent state even if the ink pressure in the flow path 209 fluctuates, and therefore cannot function as a damper to suppress fluctuations in the ink pressure. For this reason, the spring 303 reduces the bending state of the flexible membrane 302a by returning it from the maximum bent state to a less bent state when the ink pressure is not fluctuating.

[0089] In this way, the flexible film 302a can bend, so that the next time the ink pressure fluctuates, the fluctuation can be suppressed and the damper function can be performed. Note that the restoring force of the flexible film 302a itself can also act to reduce the bending of the flexible film 302a, but since the restoring force of the flexible film 302a itself can differ depending on the properties of the material of the flexible film 302a, it is effective to provide the spring 303.

[0090] For example, as shown in Fig. 3(c), when the ink pressure in the flow path 209 drops, the flexible film 302c bends and displaces toward the first space 304, suppressing the drop in ink pressure. This prevents air from entering the nozzle. After that, when the ink pressure returns to normal, the flexible film 302c is returned to a less bent state by the action of the spring 303.

[0091] 3(d), when the ink pressure in the flow path 209 increases, the flexible film 302d bends and displaces toward the second space 305, suppressing a drop in the ink pressure. This prevents ink from leaking out of the nozzles. Even in this case, when the ink pressure returns to normal, the flexible film 302c is returned to a less bent state by the action of the spring 303.

[0092] When the flexible film 302a is repeatedly bent due to the fluctuation of the ink pressure, it gradually stretches and its area increases. The flexible film 302 does not stretch uniformly as a whole, but rather the areas that are bent significantly due to the application of ink pressure are particularly prone to stretching. The flexible film 302a has a limit to how much it can stretch, and if the flexible film 302a is repeatedly bent to a point beyond the stretch limit, the flexible film 302a will break at that point, causing ink to leak from the first space 304 to the second space 305.

[0093] Since the second space 305 is surrounded by the housing 301, the ink is prevented from leaking out of the second space 305. However, if the flexible film 302a is damaged, the damping function against the pressure fluctuation of the ink is lost.

[0094] Furthermore, damage to the flexible film 302a itself may cause fluctuations in the ink pressure, which may result in problems such as destruction of the meniscus in the nozzle, entry of air into the nozzle, leakage of ink from the nozzle, etc. For this reason, it is desirable to detect signs of damage to the flexible film 302a before it is damaged, and replace the flexible film 302a, the pressure fluctuation suppressing device 200 including the flexible film 302a, or the head unit 124 including the pressure fluctuation suppressing device 200.

[0095] As described above, when the flexible film 302a is damaged by spreading, the spreading of the flexible film 302a progresses in stages. As shown in Fig. 3(b), when the flexible film 302a spreads, it is largely displaced toward the second space 305 when the ink pressure increases. For example, the displacement caused by the increase in ink pressure moves from the position indicated by the dashed line 302d before spreading to the position indicated by the solid line 302b after spreading.

[0096] With this in mind, when the difference Δh in the amount of displacement in the second space 305 compared to before spreading exceeds a predetermined threshold value and the flexible membrane 302d is displaced, by disposing a flexible membrane sensor 300 at a position where the flexible membrane 302d makes contact and detecting whether or not the flexible membrane 302d is in contact, it is possible to detect that the flexible membrane 302d has been spread to a predetermined extent.

[0097] The flexible membrane sensor 300 may be a sensor that mechanically detects contact with the flexible membrane 302d, such as a reed switch that becomes conductive or non-conductive when pressed by the extended flexible membrane 302d.

[0098] A sensor that detects the flexible film 302d in a non-contact manner, such as an optical sensor that detects whether the light path is blocked by the extended flexible film 302d, may be used. Regardless of the presence or absence of contact with the flexible film 302d, it is sufficient if the extension of the flexible film 302d can be detected based on whether the displacement amount of the flexible film 302d exceeds a threshold value.

[0099] Hereinafter, the flexible films 302a, 302b, 302c, and 302d will be collectively referred to as flexible film 302. (1-4) Configuration of the control unit 150 4, the control unit 150 includes a CPU (Central Processing Unit) 401, a ROM (Read Only Memory) 402, a RAM (Random Access Memory) 403, a HDD (Hard Disk Drive) 404, and a NIC (Network Interface Card). The CPU 401, the ROM 402, etc. are connected to each other via an internal bus 407 so as to be able to communicate with each other.

[0100] When the image forming apparatus 1 is powered on or reset, the CPU 401 reads and starts a boot program from the ROM 402, and reads and executes an OS (Operating System), a control program, and the like from the HDD 404, using the RAM 403 as a working storage area. This enables the control unit 150 to monitor and control the operating state of each unit of the image forming apparatus 1.

[0101] Note that a rewritable non-volatile memory such as an Electrically Erasable Programmable Read Only Memory (EEPROM) or a flash memory may be used instead of the ROM 402. The RAM 403 may be a non-volatile memory.

[0102] The timer 405 executes a timing process required when the CPU 401 executes a program such as a control program, etc. In other words, the timer 405 times the time from the start timing to the end timing instructed by the CPU 401, and notifies the CPU 401 when a period instructed by the CPU 401 has elapsed from the start timing instructed by the CPU 401.

[0103] The NIC 406 executes communication processing for the control unit 150 to receive a print job including image data from an external device such as a PC. The NIC 406 may perform communication via a LAN (Local Area Network) or the Internet. The NIC 406 may be a serial interface such as a USB (Universal Serial Bus) or a parallel interface.

[0104] The control unit 150 receives the detection signal of the flexible film sensor 300 and detects the spreading of the flexible film 302. When the spreading of the flexible film 302 is detected, the operation panel 160 displays the fact.

[0105] The control unit 150 controls a drive signal input to a transport drum drive motor (not shown) to rotate the transport drum 121 at a predetermined speed and timing. The control unit 150 also controls the operation of the paper feed unit 110 and the delivery unit 122 to supply the recording sheet S to the transport drum 121, and controls the operation of the delivery unit 126 to discharge the recording sheet S to the transport drum 121.

[0106] The control unit 150 controls the temperature of the paper heating unit 123 so that the recording sheet S carried on the transport drum 121 is heated to a target temperature suitable for image formation.

[0107] The control unit 150 energizes and deforms the piezoelectric element corresponding to the nozzle so that an appropriate amount of ink is ejected from each nozzle of the inkjet head constituting the head unit 124 at an appropriate timing according to image data. (1-5) Operation of the control unit 150 Among the operations of the control unit 150, particularly the operations related to the detection of the extension of the flexible membrane 302 will be described.

[0108] 5, when the control unit 150 receives a print job (S501: YES), it starts executing the received print job (S502). The control unit 150 refers to the detection signal of the flexible film sensor 300 while executing the print job (S503). When the detection signal of the flexible film sensor 300 indicates that the flexible film 302 has been detected (S504: YES), it records that the spreading of the flexible film 302 has been detected (S505).

[0109] If the print job has not been completed (S506: NO), the process proceeds to step S503 and the above process is repeated.

[0110] When the execution of the print job is completed (S506: YES), it is confirmed whether or not spreading of the flexible film 302 has been detected. When spreading of the flexible film 302 has been detected (S507: YES), the process proceeds to step S501 to wait for the next print job.

[0111] When spreading of the flexible film 302 is detected (S507: YES), a warning message is displayed on the operation panel 160 to inform the user that spreading of the flexible film 302 has been detected (S508). In this case, a warning sound may be sounded in addition to the display of the warning message. Also, since the flexible film 302 is found to be spread, there is a risk that the flexible film 302 may be damaged and a malfunction may occur due to the damage, so execution of subsequent print jobs is prohibited (S509). (1-6) Comparison with conventional technology As shown in Figure 10, in the waiting state before ink 1002 is ejected from nozzle 1001, a curved surface (meniscus) 1000 is formed in which the surface of ink 1002 indents into the inside of nozzle 1001 due to the surface tension of ink 1002 and the interaction between the surface of nozzle 1001 and ink 1002.

[0112] As described above, when the ink pressure inside the nozzle fluctuates depending on the direction of the acceleration applied to the inks 1011 and 1021, air may get into the nozzle 1012 or an ink droplet 1023 may leak from the nozzle 1022.

[0113] To address this problem, for example, a conventional technique is known in which a pressure fluctuation suppression device 11, as shown in Fig. 11, is disposed on the flow path that sends ink from an ink tank to an inkjet head. That is, a film (flexible membrane) 1101 and an elastic body 1102 such as a spring are disposed in the flow path upstream of the inkjet head, and the deformation of the flexible membrane 1101 changes the volume of the flow path, thereby absorbing the fluctuation in ink pressure.

[0114] This pressure fluctuation suppressing device 11 has an inlet 1104 that receives ink from an ink tank, and an outlet 1105 that sends ink to the inkjet head. The inside and outside of the device, in other words, the inside and outside of the flow path, are partitioned by a housing 1103. A spring 1102 is attached to the inner wall surface of the housing 1103, and the tip of the spring 1102 presses the center of a flexible film 1101.

[0115] With this configuration, when acceleration is applied to the ink in the flow path and the ink pressure fluctuates, the ink pressure in the housing 1103 of the pressure fluctuation suppression device 11 similarly fluctuates. When the flexible membrane 1101 flexes in response to this ink pressure, the volume inside the pressure fluctuation suppression device 11 fluctuates, thereby achieving a damper function that absorbs ink pressure fluctuations.

[0116] When the spring 1102 repeatedly expands and contracts in accordance with the repeated bending of the flexible film 1101, a so-called mechanochemical reaction promotes polymerization of the ink due to the sliding between the ink and the spring 1102. As a result, when the polymerized ink adheres to the spring 1102, the expansion and contraction of the spring 1102 is hindered, and bending of the flexible film 1101 is also suppressed.

[0117] If the bending of the flexible film 1101 is restricted, the pressure of the ink tends to act locally, which may cause the flexible film 1101 to spread further and become more susceptible to breakage.

[0118] To address this problem, in this embodiment, the spring 303 is disposed in the second space 305 that is separated from the ink by the flexible film 302, so there is no risk of the expansion and contraction of the spring 303 being hindered by the adhesion of ink.

[0119] Furthermore, by checking the magnitude of the displacement of the flexible membrane 302, the degree of its extension can be determined, so that signs of damage to the flexible membrane 302 can be detected before the flexible membrane 302 is damaged, thereby enhancing the effectiveness of the pressure fluctuation suppressing device 200. Therefore, various problems that may arise due to damage to the flexible membrane 302 caused by deterioration over time can be avoided.

[0120] In addition, when the flexible film 302 stretches, the response of the pressure fluctuation suppression device 200 to changes in ink pressure slows down. However, the stretching of the flexible film 302 can be detected before the response becomes too slow to adequately suppress problems such as air entering the nozzles and ink leaking from the nozzles, thereby making it possible to avoid such problems. [2] Second embodiment The image forming apparatus according to the second embodiment of the present disclosure has a configuration generally similar to that of the image forming apparatus according to the first embodiment, but differs in the configuration for detecting the extension of the flexible film in the pressure fluctuation suppressing device. The following description will focus mainly on the differences. In this specification, common reference symbols are used for components common to the embodiment and the modified examples.

[0121] As shown in FIG. 6(a), the pressure fluctuation suppressing device 200 according to this embodiment has a configuration in which a strain gauge 600 is attached to a flexible membrane 302 instead of the flexible membrane sensor 300 according to the first embodiment.

[0122] The strain gauge 600 is made by photo-etching a metal foil with a thickness on the order of microns on a lattice-shaped resistance wire on a thin base of an electrical insulator such as resin, and the electrical resistance of the metal foil changes due to expansion and contraction. By detecting the magnitude of the electrical resistance of this metal foil, the degree of bending of the flexible membrane 302 can be detected.

[0123] That is, as shown in FIG. 6(b), when the flexible film 302 stretches, the strain gauge 600 attached to the flexible film 302 is also stretched, and the electrical resistance of the strain gauge 600 changes.

[0124] In particular, when the flexible membrane 302 bends due to an increase in ink pressure in the flow path 209, if the flexible membrane 302 is stretched, the curvature of the flexible membrane 302 becomes large, and the strain gauge 600 is also stretched significantly, resulting in a particularly large change in the electrical resistance of the strain gauge 600.

[0125] When the electrical resistance of the strain gauge 600 reaches a predetermined resistance value, the control unit 150 determines that the flexible film 302a has expanded, and takes measures such as outputting a warning message as described above.

[0126] Therefore, this embodiment can also provide the same effects as those of the image forming apparatus 1 according to the first embodiment.

[0127] It goes without saying that the degree of bending of flexible membrane 302 may be detected using means other than strain gauge 600 . [3] Third embodiment While the image forming apparatus 1 of this embodiment has a configuration generally similar to that of the image forming apparatus 1 of the first and second embodiments described above, it differs in that the pressure fluctuation suppression device 200 detects the spreading of the flexible film 302 by referring to the speed of response of the flexible film 302 to ink pressure fluctuations.

[0128] That is, as shown in FIG. 7(a), the pressure fluctuation suppression device 200 is provided with an air pressure adjustment unit 700 for adjusting the air pressure in the second space 305, and this air pressure adjustment unit 700 acts as a pump to supply air into the second space 305 or exhaust air from the second space 305, thereby adjusting the air pressure in the second space 305.

[0129] Moreover, the air pressure adjustment unit 700 is equipped with an air pressure sensor 701 and can detect the air pressure in the second space 305. By supplying and discharging air while detecting the air pressure in the second space 305 with this air pressure sensor 701, the air pressure adjustment unit 700 can adjust the air pressure in the second space 305 to a desired level.

[0130] In addition, unlike the pressure fluctuation suppression device 200 according to the first and second embodiments described above, the pressure fluctuation suppression device 200 according to this embodiment does not have a spring 303, so that the flexible membrane 302 can flex freely without being restricted by the spring 303.

[0131] However, when the air pressure in the second space 305 is higher than the ink pressure in the flow path 209, the flexible membrane 302 is urged toward the first space 304 by the air pressure. Conversely, when the air pressure in the second space 305 is lower than the ink pressure in the flow path 209, the flexible membrane 302 is urged toward the second space 305.

[0132] When ink is heated prior to ejection, the heated ink may heat flexible film 302, eventually raising the temperature of the air in second space 305. In such a case, if the air pressure increases due to the rise in air temperature, the biasing force applied to flexible film 302 may change, which may reduce the damping function. Therefore, air pressure adjustment unit 700 adjusts the air pressure in second space 305 to be within an appropriate range.

[0133] Moreover, the air pressure adjustment unit 700 is, for example, partly or entirely airtightly fitted into a through hole provided in the housing 301 of the pressure fluctuation suppression device 200. The air pressure adjustment unit 700 also has an air supply / exhaust hole that communicates between the inside and outside of the second space 305, and performs air supply / exhaust via the air supply / exhaust hole using a pressure pump.

[0134] If flexible film 302 is damaged and ink leaks out from the air supply / exhaust hole of air pressure adjustment unit 700, problems such as soiling the inside of image forming apparatus 1 may occur. In order to prevent such problems as much as possible, air pressure adjustment unit 700 is desirably disposed above housing 301 of pressure fluctuation suppression device 200 in the direction of gravity.

[0135] When the flexible membrane 302 is not stretched, if the air pressure adjusting unit 700 sends air into the second space 305 to increase the air pressure, first, as the air pressure in the second space 305 increases, the flexible membrane 302 is pushed by the air pressure and moves while bending toward the first space 304. This movement continues until there is no slack in the flexible membrane 302, as exemplified by the dashed line 711 in FIG. 7(a).

[0136] Even after flexible membrane 302 is no longer loose, if the air pressure in second space 305 detected by air pressure sensor 701 is lower than the target value, air pressure adjustment unit 700 continues to supply air into second space 305. Thereafter, when air pressure sensor 701 confirms that the air pressure in second space 305 has reached the target value, air pressure adjustment unit 700 stops supplying air.

[0137] On the other hand, when the flexible film 302 is extended, it is not restricted by the spring 303, and therefore can be displaced more toward the first space 304 than the flexible film 302 according to the first and second embodiments, as shown in Fig. 7(b). For example, the amount of displacement becomes larger than the dashed line 711 illustrated in Fig. 7(a), and the flexible film 302 can be displaced to the position of the dashed line 712.

[0138] When the amount of displacement of the flexible membrane 302 toward the first space 304 increases, the volume of the second space 305 increases. Therefore, in order to increase the air pressure in the second space 305 using the air pressure adjustment unit 700, more air must be supplied than before the flexible membrane 302 was expanded.

[0139] As a result, as illustrated in FIG. 7(c), before the flexible membrane 302 is extended, the air pressure in the second space 305 rises as shown in graph 721, and the response time required for the air pressure before adjustment to reach the target value is T1, whereas after the flexible membrane 302 is extended, the air pressure in the second space 305 rises as shown in graph 722, and a response time T2 longer than the response time T1 is required for the air pressure before adjustment to reach the target value.

[0140] In this way, the response time required for the air pressure before adjustment to reach the target value becomes longer as the flexible membrane 302 stretches. By focusing on this characteristic, in this embodiment, whether the flexible membrane 302 is stretched or not is determined based on whether the response time exceeds a threshold value.

[0141] Specifically, the control unit 150 controls the air pressure adjustment unit 700 to first supply and exhaust air so that the air pressure in the second space 305 becomes a predetermined initial value. Next, the air pressure adjustment unit 700 is caused to supply air into the second space 305 while monitoring the air pressure in the second space 305 with reference to the detection signal of the air pressure sensor 701.

[0142] Timer 405 is started and begins timing at the timing of starting air supply into second space 305. Thereafter, when the air pressure in second space 305 reaches a target value, air supply by air pressure adjustment unit 700 is stopped, and timer 405 is referenced to check the response time required from the start of air supply until the air pressure reaches the target value.

[0143] This response time is compared with a predetermined threshold value, and if the response time is longer, it is determined that the flexible membrane 302 has been stretched and a warning display or the like is given, thereby achieving the same effects as in the first and second embodiments described above.

[0144] Note that, instead of increasing the air pressure in the second space 305, the response time may be measured by decreasing the air pressure in the second space 305. In this case as well, the response time can be compared with a threshold value, and the presence or absence of spreading of the flexible film 302 can be determined based on the length of the response time. In addition, the detection signal of the air pressure sensor 701 may be constantly monitored to measure the time it takes for the flexible film 302 to be displaced due to fluctuations in the ink pressure in the flow path 209, and the presence or absence of spreading of the flexible film 302 may be determined based on the length of the time.

[0145] Furthermore, in the above first to third embodiments, as shown in FIG. 2, a case has been described as an example in which the sub-tank 207 and the second space 305 of the pressure fluctuation suppression device 200 are not in communication with each other. However, it goes without saying that the present disclosure is not limited to this, and when the sub-tank 207 and the second space 305 of the pressure fluctuation suppression device 200 are in communication with each other, the following can be done.

[0146] That is, as shown in FIG. 8, in a configuration in which the second space 305 of the pressure fluctuation suppression device 200 and the sub-tank 207 are connected and air can circulate, the ink back pressure may be changed using the air pressure adjustment device 208 during maintenance work on the inkjet head 211.

[0147] In such a case, by using the air pressure sensor 800 to measure the response time required for the back pressure to reach the target value, it is possible to determine whether or not the flexible membrane 302 has expanded, without having to separately change the air pressure in the second space 305 and measure the response time. [4] Variations While the present disclosure has been described above based on the embodiments, it goes without saying that the present disclosure is not limited to the above-described embodiments, and the following modified examples can be implemented. (4-1) In the above embodiment, the use of energy beam irradiation type ink has been described as an example. However, it goes without saying that the present disclosure is not limited to this, and other types of ink or liquids other than ink may be used instead. (4-2) In the above embodiment, the pressure fluctuation suppression device 200 is described as being connected to the flow path 209 at two locations, namely, an inlet for receiving ink that has passed through the filter 210, and an outlet for sending ink to the inkjet head 211. However, it goes without saying that the present disclosure is not limited to this, and the number of communication ports with the flow path 209 may be other than two.

[0148] 9 is connected to the flow path 209 only through a communication port 901. The pressure fluctuation suppressing device 200 having such a configuration can also perform a damping function by bending the flexible film 302 in response to pressure fluctuations of the ink. Moreover, by applying the present disclosure, damage to the flexible film 302 can be predicted. (4-3) In the above embodiment, an example was described in which when spreading of the flexible film 302 is detected (FIG. 5, S507: YES), execution of subsequent print jobs is prohibited (S509). However, it goes without saying that the present disclosure is not limited to this, and instead, the following may be adopted.

[0149] The detection of spreading of the flexible film 302 does not necessarily mean that the flexible film 302 will immediately break. For this reason, even if spreading of the flexible film 302 is detected, if a warning message is merely displayed without prohibiting execution of the print job, the image forming apparatus 1 can continue to execute the print job, thereby improving user convenience until the pressure fluctuation suppressing device 200 is replaced.

[0150] On the other hand, if the print job continues to be executed, the ink is accelerated, increasing the opportunities for the ink pressure to fluctuate, which may cause the flexible film 302 to expand further and break before the pressure fluctuation suppression device 200 can be replaced. If the flexible film 302 is broken, it becomes difficult to normally supply ink from the ink tank 201 to the inkjet head 211, and therefore an image of sufficient quality cannot be formed even if the print job is executed.

[0151] For this reason, from the time when the spreading of the flexible membrane 302 is detected until the pressure fluctuation suppression device 200 is replaced, it is desirable to monitor whether ink has leaked from the damaged part of the flexible membrane 302 within the second space 305 of the pressure fluctuation suppression device 200, and to prohibit the execution of the print job if ink is detected.

[0152] As a configuration for detecting ink, for example, a pair of electrodes is disposed at a distance from one another at the bottom of the second space 305 of the pressure fluctuation suppressing device 200, and it is monitored whether the pair of electrodes is conductive or not. If the pair of electrodes is conductive, it means that the leaked ink is pooled across the pair of electrodes, and therefore it can be determined that the flexible film 302 is damaged.

[0153] If the pair of electrodes are positioned close to each other without coming into contact due to vibration, etc., they can be made conductive even with a small amount of ink, thereby increasing the sensitivity for detecting leaked ink.

[0154] Furthermore, when it is difficult to predict which part of the flexible film 302 will be damaged, pairs of electrodes may be disposed at multiple locations within the second space 305. Furthermore, in order to detect ink leakage at an early stage, it is desirable to dispose electrodes at positions close to the flexible film 302, within a range where they do not come into contact with the flexible film 302 that is bent due to fluctuations in ink pressure.

[0155] In this way, even if spreading of the flexible film 302 is detected, execution of the print job can be continued as long as high image quality is guaranteed, thereby improving user convenience. (4-4) In the above embodiment, the pressure fluctuation suppression device 200 is provided in the image forming apparatus 1. However, the present disclosure is not limited to this example, and the pressure fluctuation suppression device 200 may be provided in an apparatus other than the image forming apparatus 1.

[0156] That is, in a device that ejects liquid from a nozzle and in which problems may occur due to acceleration being applied to the liquid, the present disclosure can be applied to predict damage to the flexible film 302 due to deterioration over time. Therefore, the pressure fluctuation suppression device 200 can be replaced before the flexible film 302 is damaged, thereby preventing problems caused by damage to the flexible film 302. (4-5) In the above embodiment, an example was described in which a warning message is displayed using operation panel 160 when extension of flexible membrane 302 is detected. However, it goes without saying that the present disclosure is not limited to this, and instead of or in addition to this, the following may be performed.

[0157] That is, a warning message may be sent to an external device such as a PC. For example, if spreading of the flexible film 302 is detected while a print job is being accepted from an external device and executed, a warning message may be sent to the external device that is the sender of the print job. Also, if there is an external device that monitors the device status of the image forming device 1, a warning message may be sent to that device.

[0158] Since a user or the like is not always present near the image forming apparatus 1, if a warning message is transmitted to an external device and displayed so that it is easily visible to people, the pressure fluctuation suppressing device 200 can be promptly replaced. Therefore, it is possible to prevent the user from suffering disadvantages such as being unable to use the image forming apparatus 1 due to damage to the flexible film 302. (4-6) The above-described embodiments and modifications are merely examples of the implementation of the present disclosure, and the technical scope of the present disclosure should not be interpreted as being limited by them. The present disclosure can be implemented in various forms without departing from the gist or main characteristics thereof. [Industrial Applicability]

[0159] INDUSTRIAL APPLICABILITY The pressure fluctuation suppressing device and image forming apparatus according to the present disclosure are useful as devices capable of predicting damage to the flexible membrane caused by deterioration over time in the pressure fluctuation suppressing device. [Explanation of symbols]

[0160] 1. Image forming device 11, 200………………………Pressure fluctuation suppression device 120...................................................................Image forming unit 124………………………………Head unit 150…………………………Control unit 207………………………………IN side sub tank 208………………………………Air pressure regulator 209………………………………Flow path 211………………………………Inkjet head 300………………………………Flexible membrane sensor 301………………………………Housing 302………………………………Flexible membrane 303………………………………Spring 304………………………………First space 305………………………………Second space 600………………………………Strain gauge 700………………………………Air pressure adjustment section 701, 800……………………Air pressure sensor 1000……………………………Meniscus 1001, 1012, 1022...Nozzle

Claims

1. A suppression means is disposed in a liquid flow path and suppresses fluctuations in pressure of the liquid in the flow path; A detection means for detecting a decrease in the suppression function of the suppression means, the suppression means includes a flexible membrane that separates the inside and outside of the flow path, the flexible membrane flexes under the pressure to suppress fluctuations in the pressure; The detection means includes: a membrane displacement detection means for detecting a displacement of the flexible membrane, A decrease in the inhibitory function is detected based on the magnitude of the displacement. A pressure fluctuation suppression device characterized by:

2. The membrane displacement detection means is disposed outside the flow channel.

2. The pressure fluctuation suppressing device according to claim 1.

3. The suppression means is A first space communicating with the flow path; a second space partitioned from the first space by the flexible membrane; 3. The pressure fluctuation suppressing device according to claim 1 or 2.

4. The membrane displacement detection means is disposed in the second space.

4. The pressure fluctuation suppressing device according to claim 3.

5. The membrane displacement detection means is a contact sensor, The detection means determines the magnitude of the displacement based on whether or not the membrane displacement detection means detects contact with the flexible membrane.

5. The pressure fluctuation suppressing device according to claim 1,

6. A suppression means is disposed in a liquid flow path and suppresses fluctuations in pressure of the liquid in the flow path; A pressure fluctuation suppression device comprising: a detection means for detecting a decrease in suppression function by the suppression means, the suppression means includes a flexible membrane that separates the inside and outside of the flow path, the flexible membrane flexes under the pressure to suppress fluctuations in the pressure; The suppression means is A first space communicating with the flow path; a second space partitioned from the first space by the flexible membrane; The detection means includes: a pressure detection means for detecting a pressure in the second space; and a pressure adjusting means for adjusting the pressure in the second space, fluctuating the pressure by the pressure adjusting means, and detecting a decrease in the suppression function from a response time of the pressure detected when the pressure fluctuates; The pressure fluctuation suppression device comprises: a reservoir for the liquid disposed upstream of the pressure adjusting means in the flow path; A communication means for communicating the second space with the storage portion, The pressure adjusting means forms a common negative pressure in the second space and the storage section. A pressure fluctuation suppression device characterized by:

7. A notification means is provided for notifying an error when a deterioration in the suppression function is detected.

7. A pressure fluctuation suppressing device according to claim 1.

8. The notification means includes a display means for displaying a warning notifying an error.

8. The pressure fluctuation suppressing device according to claim 7.

9. An inkjet type image forming apparatus that forms an image by ejecting ink from a nozzle, A pressure fluctuation suppression device according to any one of claims 1 to 8, the liquid is the ink, The flow passage communicates with the nozzle.

1. An image forming apparatus comprising:

Images