Liquid supply device and liquid application device

Abstract

The present application provides a liquid supply device and a liquid coating device capable of stably and remotely ejecting a liquid of high viscosity. The liquid supply device includes: a pressurized tank supplied with compressed air from a compressed air supply source and accumulating a liquid pressurized by the compressed air; a delivery unit that delivers the liquid accumulated in the pressurized tank to a liquid flow path; a jet head having an internal flow path through which the liquid delivered from the liquid flow path flows and ejecting the liquid from the internal flow path via a nozzle; and a first moderating device provided in the liquid flow path on a downstream side of the pressurized tank and on an upstream side of the jet head, absorbing a variation in pressure of the liquid flowing in the liquid flow path, and constituting a circulation path in which the liquid circulates in the order of the pressurized tank, the first moderating device, the jet head, and the pressurized tank, the delivery unit circulating the liquid in the circulation path.

Description

Technical Field

[0001] This invention relates to a liquid supply device and a liquid coating device. Background Technology

[0002] In ink supply devices, such as inkjet printers, to transport high-viscosity inks with high solid content and settling properties in a dispersed state, the ink chamber of the printhead is also included as part of the flow path. Techniques related to the circulation and transport of the ink (hereinafter sometimes referred to as flowthrough) are known. Furthermore, as a technique for ejecting high-viscosity inks (e.g., around 1000 MPa·s) that cannot be ejected in conventional inkjet methods, airless spraying is known, which atomizes the ink by applying high pressure to rapidly eject it from the nozzle tip of the spray gun.

[0003] In the aforementioned inkjet technologies, when using water head pressure, the circulating structure operates at near atmospheric pressure. This presents a problem: it's difficult to circulate and deliver high-viscosity ink. This lack of circulation leads to ink separation and sedimentation, resulting in abnormal images due to reduced ink concentration or nozzle clogging caused by ink solids. Furthermore, the fluctuating pressure caused by the meniscus prevents the ink from being ejected over long distances. Additionally, while airless spraying can eject high-viscosity ink over greater distances, the non-flowing structure relative to the printhead causes ink separation and sedimentation, again resulting in abnormal images due to reduced ink concentration or nozzle clogging caused by ink solids.

[0004] As such inkjet technology, the disclosed configuration includes a degassing component and a differential pressure between the upstream filling tank and the downstream discharge tank of the printhead to allow flow. In order to supply ink to both tanks so that the ink in the filling tank and the discharge tank will not run out even if large droplets are ejected, when the ink in the filling tank or the discharge tank is about to run out, the flow path is switched by a solenoid valve or the like to connect the main tank to the filling tank or the discharge tank, and a pump is used to maintain a continuous flow of ink in the printhead (for example, Patent Document 1).

[0005] However, in the technology described in Patent Document 1, since it has a degassing component, it is presumably a conventional spray head. The circulation of high-viscosity ink would be difficult, so there is a problem that the high-viscosity ink cannot be stably sprayed to a distance.

[0006] The present invention was made in view of the above-mentioned problems, and its object is to provide a liquid supply device and a liquid coating device capable of stably and over a long distance spraying high-viscosity liquid.

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2020-163839 Summary of the Invention

[0008] To address the aforementioned issues and achieve the objectives, the present invention relates to a liquid supply device, characterized by comprising: a pressure tank supplied with compressed air from a compressed air supply source and storing liquid pressurized by the compressed air; a conveying unit conveying the liquid stored in the pressure tank to a liquid flow path; a nozzle having an internal flow path through which liquid conveyed from the liquid flow path passes and ejects liquid from the internal flow path via a nozzle; and a first mitigation device disposed in the liquid flow path downstream of the pressure tank and upstream of the nozzle, absorbing pressure fluctuations of the liquid flowing in the liquid flow path, and forming a circulation path in which the liquid circulates within the liquid flow path in the order of the pressure tank, the first mitigation device, the nozzle, and the pressure tank, wherein the conveying unit circulates the liquid within the circulation path.

[0009] According to the present invention, it is possible to stably and over long distances eject high-viscosity liquids. Attached Figure Description

[0010] Figure 1 The diagram shown is a schematic example of the configuration of the ink supply device according to the first embodiment.

[0011] Figure 2 (a)-(c) show a schematic diagram of the configuration of an accumulator of the ink supply device according to the first embodiment.

[0012] Figure 3 (a) and (b) show a schematic diagram of a piston pressing mechanism of an accumulator that can replace the ink supply device according to the first embodiment.

[0013] Figure 4 (a) and (b) show a schematic diagram of a configuration example of an auxiliary tank that can replace the ink supply device according to the first embodiment.

[0014] Figure 5 The diagram shown is a schematic example of a configuration of an ink supply device according to the first embodiment, used to measure the pressure and flow rate of ink flowing into the nozzle.

[0015] Figure 6 Figures (a)-(f) are example diagrams showing the comparison results of the pressure and flow rate of ink flowing into the nozzle according to the presence or absence of an accumulator in the ink supply device according to the first embodiment.

[0016] Figure 7 The diagram shown is a schematic example of the configuration of the ink supply device according to the second embodiment.

[0017] Figure 8 The diagram shown is a schematic example of the configuration of the ink supply device according to the third embodiment.

[0018] Figure 9 The diagram shown is a schematic example of a configuration of an ink supply device according to the third embodiment, used to measure the pressure and flow rate of ink upstream and downstream of the nozzle.

[0019] Figure 10 Figures (a)-(d) are example diagrams showing the comparison results of the pressure and flow rate of ink upstream and downstream of the ink supply device according to the presence or absence of an accumulator and the presence or absence of a constantly flowing nozzle.

[0020] Figure 11 Figures (a)-(d) are example diagrams showing the comparison results of the pressure and flow rate of ink upstream and downstream of the ink supply device according to the presence or absence of an accumulator and the presence or absence of a constantly flowing nozzle.

[0021] Figure 12 Figures (a)-(d) are example diagrams showing the comparison results of the amount of ink ejected from the ink supply device according to the presence or absence of an accumulator and the presence or absence of an inkjet head that is always flowing, in accordance with the third embodiment.

[0022] Figure 13 The diagram shown is a schematic example of the configuration of the ink supply device according to the fourth embodiment.

[0023] Figure 14 The diagram shown is a schematic example of the configuration of the ink supply device according to the fifth embodiment.

[0024] Figure 15 The diagram shown is a schematic example of the configuration of the ink supply device according to the sixth embodiment.

[0025] Figure 16 The diagram shown is an example of the overall appearance of the liquid coating apparatus according to the seventh embodiment.

[0026] Figure 17 The diagram shown is an example of the state in which the carriage of the printing device in the liquid coating apparatus according to the seventh embodiment is in a holding position.

[0027] Figure 18 The diagram shown is a schematic example of the configuration of an ink supply device mounted in the liquid coating apparatus according to the seventh embodiment.

[0028] Figure 19 The diagram shown is a schematic example of the configuration of the moving mechanism of the carriage of the liquid coating apparatus according to the seventh embodiment. Detailed Implementation

[0029] Hereinafter, embodiments of the liquid supply device and liquid application device of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the present invention is not limited to the following embodiments, and the constituent elements in the following embodiments include substantially the same and so-called equivalent elements that can be easily conceived by those skilled in the art. Moreover, various omissions, substitutions, changes, and combinations of the constituent elements are possible without departing from the spirit of the following embodiments.

[0030] [First Implementation Method]

[0031] (Composition of the ink supply device)

[0032] Figure 1 The diagram shown is a schematic example of the configuration of the ink supply device according to the first embodiment. Figure 2 The diagram shown is a schematic example of the configuration of the accumulator of the ink supply device according to the first embodiment. Figure 3 The diagram shown is a schematic example of a piston pressing mechanism that can replace the ink supply device according to the first embodiment. Figure 4 The diagram shown is a schematic example of a configuration of an auxiliary tank that can replace the accumulator of the ink supply device according to the first embodiment. (Refer to...) Figures 1-4 The configuration of the ink supply device 100 according to this embodiment will be described.

[0033] The ink supply device 100 (an example of a liquid supply device) is an apparatus that forms an image on a printing medium by ejecting a high-viscosity ink (hereinafter, sometimes referred to as high-viscosity ink or simply ink) that is a thixotropic non-Newtonian fluid from the ejector head 123 while the ink is flowing through it. Furthermore, while this embodiment uses ink as an example for explanation, it can generally be applied to high-viscosity liquids that are thixotropic non-Newtonian fluids. Figure 1 As shown, the ink supply device 100 includes a high-pressure air supply source 200 (compressed air supply source), a regulator 111, a pressurization tank 101, a stirring device 103, a pump 121 (an example of a delivery unit), a filter 122, an accumulator 131 (an example of a first buffer device), a pressure gauge 115, a nozzle 123, a nozzle opening and closing control device 125, a pressure control device 117 (a first control device), and a control device 300.

[0034] The high-pressure air supply source 200 is connected to the pressurization tank 101 via the air supply path 201, and is an air supply source used to supply high-pressure air compressed by a compressor or the like to the pressurization tank 101. The high-pressure air supply source 200 supplies air compressed at a pressure above atmospheric pressure to the pressurization tank 101, for example.

[0035] The regulator 111, installed on the air supply path 201, is a device that reduces the pressure of high-pressure air supplied from the high-pressure air supply source 200 to an arbitrary pressure. Specifically, the regulator 111 adjusts the pressure of the air supplied from the air supply path 201 to an arbitrary pressure that is higher than atmospheric pressure and lower than the pressure of the air compressed by the high-pressure air supply source 200, using this pressure to pressurize the high-viscosity ink, i.e., ink IK1, filled in the pressurization tank 101. Furthermore, the pressure reduction adjustment performed by the regulator 111 can be done, for example, manually.

[0036] The pressurized tank 101 is a container for storing ink IK1, which is a high-viscosity ink. An air supply passage 201 is connected to the upper part of the pressurized tank 101. Compressed air from the high-pressure air supply source 200 and via the regulator 111 is supplied to the pressurized tank 101 to pressurize the ink IK1 inside. In addition, an ink flow passage 203 (an example of a liquid flow passage) is connected to the lower part of the pressurized tank 101, which allows the ink IK1 to flow out. This ink flow passage 203 is connected to the ejector head 123. That is, the ink flow passage 203, as a "liquid flow passage," refers to the flow path from the pressurized tank 101 to the ejector head 123.

[0037] In addition, the pressurized tank 101 may also include, for example, a water level gauge capable of measuring the filling amount of ink IK1, an ink temperature regulating device such as a heater or cooler for managing the viscosity of ink IK1, and a thermometer for temperature management and control of ink IK1.

[0038] The stirring device 103 is used to stir the ink liquid IK1 filled in the pressurized tank 101. The stirring device 103 includes a stirring motor 103a and a stirring paddle 103b.

[0039] The stirring motor 103a is a motor device used to stir the ink liquid IK1 by rotating and driving the stirring paddle 103b. The on / off operation of the stirring motor 103a is controlled by the control device 300.

[0040] The stirring paddle 103b is a stirring component that rotates and stirs the ink IK1 by rotating the stirring motor 103a.

[0041] Pump 121 is located downstream of pressurized tank 101 (the side where ink flows out) and upstream of accumulator 131 (the side where ink flows in) on ink flow path 203. It is a pump device that pressurizes and delivers the ink IK1 stored in pressurized tank 101 towards accumulator 131 along the direction of arrow A in ink flow path 203. Pump 121 is a diaphragm pump that has a membrane, which is an elastic body separating the ink from the structure, and pressurizes the ink by the contraction of this diaphragm. The rotational speed of pump 121 is controlled by pressure control device 117.

[0042] The filter 122 is located downstream of the pump 121 on the ink flow path 203 and is a device for removing foreign matter from the ink pumped by the pump 121.

[0043] An accumulator 131 is located downstream of the filter 122 and upstream of the nozzle 123 in the ink flow path 203. It is an accumulator that mitigates pressure fluctuations by absorbing and replenishing the pressure changes of the ink flowing within it. Specifically, the accumulator 131 is located downstream of the pressurized tank 101 and upstream of the nozzle 123 in the ink flow path 203, absorbing pressure changes in the ink flowing within the ink flow path 203. The accumulator 131 has the function of converting the pressure energy of liquid ink into the pressure energy of gas and accumulating it. Specifically, for the pressure energy applied to the liquid ink, the accumulator 131 absorbs the pressure energy by reducing the volume of gas. On the other hand, when the pressure energy of the ink is lost, the pressure energy of the gas is used to replenish the pressure energy of the liquid. Because of this function, it can absorb and replenish the pressure changes, thus mitigating pressure fluctuations. In this case, since the ink flow path 203 is closed, the increase or decrease of ink pressure is essentially the same as the increase or decrease of ink flow rate. Therefore, the accumulator 131 also functions as a moderating agent for the ink flow rate.

[0044] For example, such as Figure 2 As shown in (a), the accumulator 131 has a main body 131a and a membrane 131b. The membrane 131b, referred to as a prander, is filled with a gas such as nitrogen. In order to effectively utilize the accumulator 131 to mitigate pressure fluctuations in the ink, a gas such as nitrogen is filled into the membrane 131b at a filling pressure of approximately 60% of the ink pressure. When the pressure of the ink flowing in the ink flow path 203 is low, such as... Figure 2 As shown in (a), the gas sealed in the membrane 131b expands, and the membrane 131b becomes tightly connected to the inner wall surface of the body 131a. Then, when the pressure of the ink flowing in the ink flow path 203 increases, as... Figure 2As shown in (b), the gas-sealed membrane 131b shrinks, the gas is compressed, and the gas absorbs the pressure energy of the ink. On the other hand, when the pressure of the ink flowing in the ink flow path 203 decreases, as... Figure 2 As shown in (c), the gas-filled membrane 131b expands, imparting pressure energy to the ink from the gas. Through these actions, the accumulator 131 functions to maintain a constant pressure of the ink flowing in the ink flow path 203, thereby mitigating pressure fluctuations in the ink.

[0045] In addition, Figure 1 In the example shown, an accumulator 131 is used as a device to mitigate pressure fluctuations in the ink flowing in the ink flow path 203, but it is not limited to this. Other devices may also be used as devices to mitigate these pressure fluctuations. Figure 3 The piston pressing mechanism 131-2 shown (an example of the first buffer device) or Figure 4 The auxiliary tank 131-3 (an example of the first buffer device) shown is used instead of the accumulator 131.

[0046] For example, such as Figure 3 As shown, the piston pressing mechanism 131-2 includes a buffer 131-2a, a cylinder 131-2b, and a piston 131-2c. Figure 3 (a) and Figure 3 As shown in (b), the buffer 131-2a is a component used to attenuate and absorb pressure changes exerted on the connected piston 131-2c by the ink flowing in the ink flow path 203. The cylinder 131-2b is a cylindrical component, and the piston 131-2c, connected to the buffer 131-2a, can slide along its inner wall. The piston 131-2c, connected to the buffer 131-2a, is a component capable of sliding back and forth along the inner wall of the cylinder 131-2b. Pressure changes from the ink flowing from the bottom surface of the piston 131-2c are absorbed by the buffer 131-2a connected to the piston 131-2c. Through this action, the piston pressing mechanism 131-2 functions to maintain a constant pressure of the ink flowing in the ink flow path 203, thereby mitigating pressure fluctuations in the ink.

[0047] like Figure 4 As shown, the auxiliary tank 131-3 is a tank component internally sealed with high-pressure gas. When the pressure of the ink flowing in the ink flow path 203 increases, as... Figure 4 As shown in (a), the sealed gas shrinks and is compressed, thus absorbing the pressure energy of the ink. On the other hand, when the pressure of the ink flowing in the ink flow path 203 decreases, as... Figure 4As shown in (b), the sealed gas expands and imparts pressure energy to the ink. Through these actions, the auxiliary tank 131-3 functions to maintain a constant pressure of the ink flowing in the ink flow path 203, thereby mitigating pressure fluctuations in the ink.

[0048] Pressure gauge 115 is a pressure gauge that measures the pressure of ink flowing in ink flow path 203. Figure 1 In this example, pressure gauge 115 is located downstream of accumulator 131 and upstream of ejector head 123 on ink flow path 203. It measures the pressure after subtracting the discharge pressure from pump 121 when discharging ink from the pressurized ink IK1 applied by high-pressure air supply source 200 to pressurized tank 101, and the pressure loss in each device upstream of pressure gauge 115 on ink flow path 203. To achieve stable ink ejection from nozzle of ejector head 123, the pressure of ink flowing to ejector head 123 needs to be stabilized. Therefore, to measure the pressure of ink flowing to ejector head 123 as accurately as possible, it is preferable to not place any components other than ink flow path 203 between pressure gauge 115 and ejector head 123, and to place pressure gauge 115 as close as possible upstream of ejector head 123 to minimize ink pressure loss. In this case, the pressure of ink flowing to ejector head 123 measured by pressure gauge 115 is called ejection pressure. The pressure data of the ink measured by pressure gauge 115 is sent to pressure control device 117.

[0049] The printhead 123 is an inkjet head equipped with one or more nozzles that can be opened and closed, and from which high-viscosity ink is ejected. The opening and closing of the nozzles of the printhead 123 is controlled by a nozzle opening and closing control device 125. Specifically, the printhead 123 uses an actuator to operate a needle to open and close the nozzles. This method involves lifting a needle with a cap (stopper) on the nozzle by an actuator, allowing ink to flow out through the nozzle. At this time, if the ink flow is stopped by pressing the needle to quickly cover (stop) the nozzle, the flowing ink will become droplets and be ejected rapidly in the direction approximately towards the centerline of the nozzle, falling onto the printing medium while maintaining a droplet state until about 50 mm. For example, the configuration of the printhead 123 can be the one disclosed in Japanese Patent Application Publication No. 2004-142382. Furthermore, the ejector head 123 has an internal flow path (not shown) that communicates with one or more nozzles. One end, serving as an inlet, is connected to the ink flow path 203, and the other end, serving as an outlet, is connected to the ink flow path 204 (an example of a liquid flow path). That is, ink supplied from the ink flow path 203 flows through the aforementioned internal flow path and is ejected from this internal flow path via the nozzles. The ink flow path 204 is connected to the upper part of the pressurization tank 101. In other words, the ink flow path 204, as a "liquid flow path," represents the flow path from the ink flowing out of the internal flow path (internal flow path) of the ejector head 123 until it flows into the pressurization tank 101. Thus, a circulation path is formed in which the ink repeatedly circulates within the liquid flow path formed by the ink flow path 203 and the ink flow path 204 in the order of pressurization tank 101, accumulator 131, ejector head 123, and pressurization tank 101. Driven by pump 121, ink is delivered in the direction of arrow A within the circulation path, resulting in ink also flowing through nozzle 123. This state, where ink flows through nozzle 123 through circulation in the aforementioned circulation path, is termed flow. Furthermore, the state where pump 121 is driven both when nozzle 123 is ejecting ink and when it is not ejecting ink, resulting in continuous ink flow through nozzle 123 (the state where pump 121 circulates ink within the circulation path), is termed constant flow.

[0050] The nozzle opening and closing control device 125 is a device that controls the opening and closing of the nozzle by operating the needle of the spray head 123 with an actuator.

[0051] The pressure control device 117 receives ink pressure data measured by the pressure gauge 115 and freely controls the rotation speed of the pump 121 to achieve an arbitrary pressure (prescribed value). Furthermore, the pressure control device 117 is linked to the nozzle opening / closing control device 125, controlling the rotation speed of the pump 121 based on the ink pressure (ejection pressure) measured by the pressure gauge 115 when the nozzle of the ejector head 123 is not open, thereby enabling stable ink pressure control. At this time, the pressure control device 117 can detect the nozzle opening / closing state of the nozzle of the nozzle opening / closing control device 125 via the control device 300.

[0052] Furthermore, the pressure control device 117 can temporarily increase or decrease the ejection pressure by controlling the rotational speed of the pump 121. For example, if solids are dispersed in the ink, or if condensed ink or foreign matter accumulates in the filter 122, the fluid resistance in the filter 122 increases, and the ink pressure, i.e., the ejection pressure, measured by the downstream pressure gauge 115, decreases. In this case, the pressure control device 117 can adjust the ejection pressure of the pump 121 based on the ink pressure measured by the pressure gauge 115 (in this case, increasing), thereby stabilizing the ejection pressure at a certain value. Additionally, for example, to restore the nozzle of the ejector head 123 from an abnormal state such as ink blockage, as a nozzle cleaning process, the pressure control device 117 can also temporarily increase the ink discharge rate of the pump 121 (increasing the discharge pressure) according to the instruction from the upper control device 300, thereby increasing the ejection pressure and expelling the ink blocked in the nozzle.

[0053] The control device 300 is a controller that controls the overall operation of the ink supply device 100. For example, the control device 300 performs on / off control of the stirring action of the stirring device 103, control of the nozzle opening and closing control device 125, and control of the pressure control device 117.

[0054] In addition, the ink supply device 100 is not only Figure 1 The constituent elements shown may also include other constituent elements. For example, the ink supply device 100 may also include a flow path opening / closing valve, which consists of a solenoid valve for controlling the start and stop of ink flow, a safety valve for opening the high pressure of the pressurized tank 101 to the atmosphere, and a discharge switching flow path for discharging ink from the circulation path.

[0055] (Regarding the stabilization of ink pressure and flow rate)

[0056] Figure 5 The diagram shown is a schematic example of a configuration of an ink supply device according to the first embodiment, used to measure the pressure and flow rate of ink flowing into the nozzle. Figure 6The diagram shown is an example of a graph comparing the pressure and flow rate of ink flowing into the ejector head based on the presence or absence of an accumulator in the ink supply device according to the first embodiment. (Refer to...) Figure 5 and Figure 6 The stabilization of the pressure (ejection pressure) and flow rate of the ink flowing to the ejector head 123 by the accumulator 131 of the ink supply device 100 according to this embodiment will be explained.

[0057] As described above, since the pump 121 has a diaphragm, the ink inside the pump 121 does not come into contact with the internal structures, making it difficult for foreign matter to enter. However, on the other hand, the periodic fluctuations (pulsations) in the pressure and flow rate of the ink caused by the contraction of the diaphragm can become an obstacle to maintaining a stable ejection pressure. As described above, the ink supply device 100 according to this embodiment, having an accumulator 131 provided downstream of the filter 122 on the ink flow path 203 and upstream of the ejector head 123, can suppress the pulsations in ink pressure and flow rate caused by the driving of the pump 121.

[0058] Furthermore, when ink is ejected from the ejector head 123, the ejection pressure decreases because the pressure of the ink flowing within the ejector head 123 is released to the atmosphere during the nozzle opening period. Moreover, the sum of the increase in flow rate corresponding to the amount of ink ejected upstream of the ejector head 123 and the decrease in flow rate corresponding to the amount of ink ejected downstream of the ejector head 123, generated by ejecting ink from the nozzles of the ejector head 123, constitutes a variation in the flow rate of the ink flowing into the ejector head 123. In other words, when ink is ejected from the ejector head 123, the ink pressure (ejection pressure) and flow rate change drastically. When ink is ejected intermittently and continuously from the multiple nozzles of the ejector head 123, the ejection pressure at a given moment can be considered to be non-constant (crosstalk) due to the ejection conditions of nearby nozzles, including itself, up to the previous moment. As described above, the ink supply device 100 according to this embodiment includes an accumulator 131 located downstream of the filter 122 on the ink flow path 203 and upstream of the nozzle 123, thereby suppressing pressure and flow rate fluctuations caused by the ejection of ink from the nozzle 123.

[0059] Here, refer to Figure 5 and Figure 6 A specific example will be described regarding the effect of stabilizing the pressure (ejection pressure) and flow rate of ink flowing from the accumulator 131 to the ejector head 123 in the ink supply device 100 according to this embodiment. Figure 5 In the ink supply device 100 shown, in order to measure the flow rate of ink flowing into the ejector head 123, relative to... Figure 1The ink supply device 100 shown has a flow meter 140 installed downstream of the accumulator 131 and upstream of the pressure gauge 115 on the ink flow path 203. Then, in Figure 5 In the ink supply device 100 shown, pump 121 circulates the ink in a circulation path. In this case, Figure 6 The image shown is related to... Figure 5 The graphs shown show the pressure (measured by pressure gauge 115) and flow rate (measured by flow meter 140) of the ink flowing to the print head 123 in the configuration of the ink supply device 100 with and without the accumulator 131.

[0060] Figure 6 The graph shown in (a) is a time series representation of the pressure and flow rate of ink flowing to the ejector head 123 without the accumulator 131 installed. On the other hand, Figure 6 The graph shown in (d) is a time-series representation of the pressure and flow rates of ink flowing towards the ejector head 123 when the accumulator 131 is installed. Furthermore, since each graph uses raw data measured by the pressure gauge 115 and flow meter 140, the accompanying description contains minor noise. Comparing the graphs clearly shows that... Figure 6 As shown in the chart (d), Figure 6 The periodic variations (amplitude) in ink pressure and flow rate that appear in graph (a) are significantly suppressed.

[0061] Figure 6 The graph shown in (b) is the result of a Fast Fourier Transform (FFT) analysis of the pressure of the ink flowing into the ejector head 123 without the accumulator 131 installed. On the other hand, Figure 6 The graph shown in (e) is the result of an FFT analysis of the pressure values ​​of the ink flowing into the ejector head 123 with the accumulator 131 installed. Comparing the two graphs, it is clear that without the accumulator 131, peaks occur at two specific frequencies, indicating strong pressure fluctuations. The frequencies of these peaks increase as the pump 121's discharge rate increases, i.e., the pump 121's rotational speed is increased, indicating that the cause is the pump 121's rotational speed. On the other hand, these peaks are not found in the graph with the accumulator 131 installed, indicating that pressure fluctuations at that frequency are suppressed.

[0062] in addition, Figure 6 The graph shown in (c) is the result of an FFT analysis of the ink flow rate to the ejector head 123 without the accumulator 131 installed. On the other hand, Figure 6The graph shown in (f) is the result of an FFT analysis of the ink flow rate to the ejector head 123 with the accumulator 131 installed. Comparing the two graphs, it is clear that without the accumulator 131, peaks occur at two specific frequencies, indicating strong fluctuations in the flow rate. Similarly, the frequencies of these peaks increase as the pump 121's discharge rate increases, i.e., the pump 121's rotational speed is increased, indicating that the cause is the pump 121's rotational speed. On the other hand, these peaks are not found in the graph with the accumulator 131 installed, indicating that fluctuations in the flow rate at that frequency are suppressed.

[0063] From the above, it can be seen that, Figure 6 As shown, by providing an accumulator 131 on the downstream side of the filter 122 (downstream side of the pump 121) and upstream side of the nozzle 123 on the ink flow path 203, the pressure and flow rate fluctuations of the ink caused by the drive of the pump 121 can be suppressed to the point that peaks cannot be detected even when FFT analysis is performed.

[0064] As described above, in the ink supply device 100 according to this embodiment, the pressurized tank 101 is supplied with compressed air by the high-pressure air supply source 200 and stores ink pressurized by the compressed air. A pump 121 is installed in the ink flow path 203 downstream of the pressurized tank 101 and upstream of the accumulator 131, and pumps the ink in the pressurized tank 101 toward the accumulator 131 into the ink flow path 203. The nozzle 123 is configured to pump ink from the ink flow path 203... The ink flows through an internal flow path, from which ink is ejected through a nozzle. An accumulator 131 is located in the ink flow path 203 downstream of the pressurized tank 101 and upstream of the ejector head 123, absorbing pressure fluctuations in the ink flowing within the ink flow path 203. This creates a circulation path in which the ink circulates within the ink flow path in the sequence of pressurized tank 101, accumulator 131, ejector head 123, and pressurized tank 101 again. The pump 121 circulates the ink within this circulation path. This suppresses pressure and flow rate fluctuations caused by the ejection of ink from the ejector head 123, enabling the stable and long-distance ejection of high-viscosity ink (an example of a liquid). Furthermore, it suppresses pressure and flow rate pulsations in the ink caused by the driving of the pump 121.

[0065] [Second Implementation]

[0066] The ink supply device according to the second embodiment will be described focusing on the differences from the ink supply device 100 according to the first embodiment. In this embodiment, the configuration in which an accumulator is also provided on the downstream side of the ejector head 123 will be described.

[0067] Figure 7 The diagram shown is an example of the configuration of the ink supply device according to the second embodiment. (Refer to...) Figure 7 The configuration of the ink supply device 100a according to this embodiment will be described.

[0068] like Figure 7 As shown, the ink supply device 100a includes a high-pressure air supply source 200 (compressed air supply source), a regulator 111, a pressurization tank 101, a stirring device 103, a pump 121 (an example of a delivery unit), a filter 122, an accumulator 131 (an example of a first buffering device), a pressure gauge 115, a nozzle 123, a nozzle opening and closing control device 125, an accumulator 132 (an example of a second buffering device), a pressure control device 117 (a first control device), and a control device 300. That is, the configuration of the ink supply device 100a is the same as that of the ink supply device 100 according to the first embodiment described above, except that it includes the accumulator 132.

[0069] Accumulator 132 is located on the ink flow path 204 immediately downstream of the print head 123. It is an accumulator that mitigates pressure fluctuations by absorbing and filling the ink flowing inside it with pressure changes. Specifically, accumulator 132 is located on the ink flow path 204 downstream of the print head 123 and upstream of the pressurized tank 101, and absorbs pressure fluctuations in the ink flowing in the ink flow path 204. The configuration of accumulator 132 is the same as that of accumulator 131, but the above-described configuration can also be used. Figure 3 The piston pressing mechanism 131-2 shown (an example of the second buffer device) or Figure 4 The auxiliary tank 131-3 shown (an example of a second buffer device) is used instead of the accumulator 132.

[0070] In the nozzles located at the upstream side of the circulation path within the ejector head 123, i.e. the nozzle closest to the accumulator 131, and the nozzles located at the downstream side of the circulation path, i.e. the nozzles farthest from the accumulator 131, the pressure loss varies due to differences in the shape and distance of the circulation path within the ejector head 123 up to the accumulator 131. Therefore, the pressure of the ink may be uneven.

[0071] The ejector head 123 can move freely within the printable area of ​​the image forming apparatus equipped with the ink supply device 100a. To eject ink at any position within this printable area, multiple nozzles are arranged with the narrowest possible spacing between them. While it is possible to provide a damping effect to each nozzle equally, this is impractical given the size and layout of the ejector head 123. Therefore, in this embodiment, as described above, an accumulator 132 is provided on the ink flow path 204 immediately downstream of the ejector head 123. This allows for a more uniform damping effect on all nozzles of the ejector head 123 and more effectively suppresses pressure and flow rate fluctuations caused by the ejection of ink from the ejector head 123.

[0072] It should be noted that, in order to reduce pressure loss in the flow path, the accumulator 132 is preferably located as close as possible to the downstream side of the nozzle 123.

[0073] [Third Implementation Method]

[0074] The ink supply device according to the third embodiment will be described focusing on the differences from the ink supply device 100 according to the first embodiment. In this embodiment, the configuration in which a pressure tank is provided in addition to the pressure tank 101 will be described.

[0075] (Composition of the ink supply device)

[0076] Figure 8 The diagram shown is an example of the configuration of the ink supply device according to the third embodiment. (Refer to...) Figure 8 The configuration of the ink supply device 100b according to this embodiment will be described.

[0077] like Figure 8 As shown, the ink supply device 100b includes a high-pressure air supply source 200 (compressed air supply source), a regulator 111 (first regulator), a pressurization tank 101 (first pressurization tank), a stirring device 103, a regulator 112 (second regulator), a pressurization tank 102 (second pressurization tank), a stirring device 104, a pump 121, a filter 122, a flow meter 140, an accumulator 131 (an example of a first buffer device), a pressure gauge 115, a nozzle 123, a nozzle opening and closing control device 125, a pressure and flow control device 118 (second control device), and a control device 300b.

[0078] The regulator 111, installed on the air supply path 201, is a device that reduces the pressure of high-pressure air supplied from the high-pressure air supply source 200 to an arbitrary pressure (first pressure). Specifically, the regulator 111 adjusts the pressure of the air supplied from the air supply path 201 to an arbitrary pressure that is higher than atmospheric pressure and lower than the pressure of the air compressed by the high-pressure air supply source 200, using this pressure to pressurize the high-viscosity ink, i.e., ink IK1, stored in the pressurization tank 101. Furthermore, the pressure reduction adjustment performed by the regulator 111 is controlled by the pressure-flow control device 118, described later.

[0079] Regulator 112 is installed on air supply path 202, which branches off from air supply path 201. It is a regulator device that reduces the pressure of air supplied from high-pressure air supply source 200 and passing through regulator 111 to a predetermined pressure (second pressure) lower than a first pressure. Specifically, regulator 112 adjusts the pressure of air supplied from air supply path 201 and passing through regulator 111 to an arbitrary pressure higher than atmospheric pressure and lower than the pressure of the air reduced by regulator 111. This pressure is used to pressurize the high-viscosity ink, i.e., ink IK2, filled in pressurization tank 102. Furthermore, the pressure reduction adjustment performed by regulator 112 is controlled by pressure flow control device 118, described later. Air supply path 202, where regulator 112 is installed, is connected to the upper part of pressurization tank 102, described later.

[0080] The pressurized tank 102 is a container that stores ink IK2, which is a high-viscosity ink. An air supply passage 202 is connected to the upper part of the pressurized tank 102. Compressed air from a high-pressure air supply source 200, passing through regulators 111 and 112, is supplied to the pressurized tank 102 to pressurize the ink IK2 inside. Furthermore, an ink flow passage 205 (an example of a liquid flow passage) is connected to the lower part of the pressurized tank 102, allowing ink IK2 to flow out. This ink flow passage 205 is connected to the upper part of the pressurized tank 101. That is, the ink flow passage 205, as a "liquid flow passage," represents the flow path from the ink flowing out of the pressurized tank 102 to the pressurized tank 101. Additionally, an ink flow passage 204, connected to the discharge port of the nozzle flow passage in the print head 123, is also connected to the upper part of the pressurized tank 102. Therefore, the ink flowing out of the nozzle flow path of the print head 123 is transported to the pressurization tank 102 via the ink flow path 204. The ink stored in the pressurization tank 102 is supplied (transported) to the pressurization tank 101 by the pump 121, and the ink stored in the pressurization tank 101 is transported to the accumulator 131 side by the pump 121.

[0081] In addition, the "conveying unit" of the present invention corresponds to the pressurizing tank 101, pressurizing tank 102, regulator 111, regulator 112 and pump 121.

[0082] This creates a circulation path where the ink repeatedly circulates within the liquid flow path comprised of ink flow path 203, ink flow path 204, and ink flow path 205, following the sequence of pressurized tank 101, accumulator 131, nozzle 102, pressurized tank 102, and pressurized tank 101. Furthermore, by reducing pressure through regulators 111 and 112, a pressure difference is created between pressurized tank 101 and pressurized tank 102. This pressure difference causes the ink to be transported from the bottom of pressurized tank 101 in the direction of arrow A, circulating within the circulation path and also flowing through nozzle 123. Thus, in the ink supply device 100b according to this embodiment, ink also flows through nozzle 123. Furthermore, the state in which ink continuously flows through the print head 123 due to the aforementioned pressure difference, whether ink is being ejected or not (the state in which the pressurized tank 101, pressurized tank 102, regulator 111, and regulator 112 cause the ink to circulate in the circulation path) is called constant flow.

[0083] In addition, the pressurized tank 102 may also include, for example, a water level gauge capable of measuring the filling amount of ink IK2, an ink temperature regulating device such as a heater or cooler for managing the viscosity of ink IK2, and a thermometer for temperature management and control of ink IK2.

[0084] The stirring device 104 is used to stir the ink liquid IK2 filled in the pressurized tank 102. The stirring device 104 includes a stirring motor 104a and a stirring paddle 104b.

[0085] The stirring motor 104a is a motor device used to stir the ink liquid IK2 by rotating and driving the stirring paddle 104b. The on / off operation of the stirring motor 104a is controlled by the control device 300b.

[0086] The stirring paddle 104b is a stirring component that rotates and stirs the ink IK2 by rotating the stirring motor 104a.

[0087] Pump 121, installed on ink flow path 205, is a pump device that pressurizes ink IK2 in pressurized tank 102 towards ink flow path 205 in the direction of arrow B. Ink in pressurized tank 102 continuously flows into pressurized tank 101 via a circulation path. On the other hand, ink in pressurized tank 101 continuously flows out of ink flow path 203 via air pressurized by regulator 111, and will eventually be depleted. Therefore, by driving pump 121, ink in pressurized tank 102 is continuously or intermittently returned to pressurized tank 101 via ink flow path 205. Pump 121 internally has a membrane, called a diaphragm, which is an elastic body separating the ink and the structure, and pressurizes the ink by the contraction of this diaphragm. The rotational speed of pump 121 is controlled by pressure and flow control device 118.

[0088] The flow meter 140 is installed downstream of the filter 122 on the ink flow path 203 and measures the flow rate of ink flowing in the ink flow path 203. Then, an accumulator 131 is installed downstream of the flow meter 140 on the ink flow path 203.

[0089] Pressure gauge 115 is a pressure gauge that measures the pressure of ink flowing in ink flow path 203. Figure 8 In this example, pressure gauge 115 is located downstream of accumulator 131 and upstream of nozzle 123 on ink flow path 203. It measures the pressure after subtracting pressure losses in the devices upstream of pressure gauge 115 from the pressure applied by high-pressure air supply source 200 to ink IK1 in pressurized tank 101. The pressure data of the ink measured by pressure gauge 115 is sent to pressure flow control device 118.

[0090] The pressure-flow control device 118 receives ink pressure data measured by the pressure gauge 115 and controls the pressure reduction actions of regulators 111 and 112 to achieve an arbitrary pressure (prescribed value). Furthermore, the pressure-flow control device 118 is linked to the nozzle opening / closing control device 125, controlling the pressure reduction actions of regulators 111 and 112 based on the ink pressure (ejection pressure) measured by the pressure gauge 115 when the nozzle of the ejector head 123 is not open, thereby enabling stable ink pressure control. At this time, the pressure-flow control device 118 can detect the opening state of the nozzle of the nozzle opening / closing control device 125 via the control device 300b. Additionally, the pressure-flow control device 118 receives ink flow data measured by the flow meter 140 and controls the drive time and speed of the pump 121 to prevent the ink IK1 in the pressurized tank 101 from running dry.

[0091] Furthermore, the pressure flow control device 118, by controlling the pressure reduction process of regulators 111 and 112, can control the pressure difference between pressurized tank 101 and pressurized tank 102, thereby temporarily adjusting the ejection pressure. For example, if solids are dispersed in the ink, or if condensed ink or foreign matter accumulates in the filter 122, the fluid resistance in the filter 122 increases, and the ink pressure measured by the downstream pressure gauge 115, i.e., the ejection pressure, decreases. In this case, the pressure flow control device 118 can adjust the pressure setpoint for regulator 111 based on the ink pressure measured by pressure gauge 115 (in this case, increasing), thereby stabilizing the ejection pressure at a certain value. In addition, when the pressure difference between the pressurizing tank 101 and the pressurizing tank 102 increases, the ink flow rate will increase. Therefore, the pressure flow control device 118 can control the pressure difference between the pressurizing tank 101 and the pressurizing tank 102 by increasing the discharge of the pump 121, extending the normal operating time, or changing the pressure setting value of the regulator 112.

[0092] The control device 300b is a controller that controls the overall operation of the ink supply device 100b. For example, the control device 300b performs on / off control of the stirring action of the stirring device 103 and the stirring device 104, controls the nozzle opening and closing control device 125, and controls the pressure and flow control device 118.

[0093] In addition, the ink supply device 100b is not only Figure 8 The constituent elements shown may also include other constituent elements. For example, the ink supply device 100b may also include a flow path opening / closing valve, which consists of a solenoid valve for controlling the start and stop of ink flow, a safety valve for opening the high pressure of the pressurized tank 101 and pressurized tank 102 to the atmosphere, and a discharge switching flow path for discharging ink from the circulation path.

[0094] (Regarding the stabilization of ink pressure and flow rate)

[0095] Figure 9 The diagram shown is a schematic example of a configuration of an ink supply device according to the third embodiment, used to measure the pressure and flow rate of ink upstream and downstream of the nozzle. Figure 10 The diagram shown is an example of a graph comparing the pressure and flow rate of ink upstream and downstream of the ink supply device according to the presence or absence of an accumulator and the presence or absence of a constantly flowing nozzle. Figure 11 The diagram shown is an example of a graph comparing the pressure and flow rate of ink upstream and downstream of the ink supply device according to the presence or absence of an accumulator and the presence or absence of a constantly flowing nozzle. Figure 12The diagram shown is an example of a graph comparing the ink ejection volume of a printhead with and without an accumulator and with and without constant flow, in the ink supply device according to the third embodiment. (Refer to...) Figures 9-12 The stabilization of the pressure (ejection pressure) and flow rate of the ink flowing to the ejector head 123 by the accumulator 131 of the ink supply device 100b according to this embodiment will be explained.

[0096] In this embodiment, as described above, pump 121 prevents the ink IK1 in pressure tank 101 from running out by returning the ink in pressure tank 102 to pressure tank 101 via ink flow path 205. Then, through the pressure difference between pressure tank 101 and pressure tank 102, ink IK1 is conveyed from the bottom of pressure tank 101 in the direction of arrow A and circulates within the circulation path. Therefore, the pressure of the ink flowing to the ejector head 123 (ejection pressure) is not affected by the pulsation of pump 121.

[0097] On the other hand, similar to the first embodiment described above, when ink is ejected from the ejector head 123, the ejection pressure decreases because the pressure of the ink flowing within the ejector head 123 is released to the atmosphere during the nozzle opening period. Furthermore, the sum of the increase in flow rate corresponding to the amount of ink ejected upstream of the ejector head 123 and the decrease in flow rate corresponding to the amount of ink ejected downstream of the ejector head 123, generated by ejecting ink from the nozzle of the ejector head 123, results in a change in the flow rate of the ink flowing to the ejector head 123. That is, when ink is ejected from the ejector head 123, the ink pressure (ejection pressure) and flow rate change drastically. The ink supply device 100b according to this embodiment includes an accumulator 131 located downstream of the filter 122 on the ink flow path 203 and upstream of the ejector head 123, thus suppressing the pressure and flow rate changes caused by the ejection of ink from the ejector head 123.

[0098] Here, refer to Figures 9-12 In the ink supply device 100 according to this embodiment, a specific example will be described to illustrate the effect of the accumulator 131 on stabilizing the pressure (ejection pressure) and flow rate of the ink when it is ejected from the ejector head 123. Figure 9 In the ink supply device 100b shown, in order to measure the pressure and flow rate of the ink on the downstream side of the ejector head 123, relative to... Figure 8 The ink supply device 100b shown has a flow meter 141 and a pressure gauge 116 arranged downstream of the nozzle 123 on the ink flow path 203. Further, in Figure 9In the ink supply device 100b shown, the pressure of the ink upstream of the ejector head 123 when ink is ejected from the ejector head 123 is measured in order to measure the pressure after the damping effect generated by the accumulator 131. Figure 8 Compared to the ink supply device 100b shown, the configuration of the pressure gauge 115 and the accumulator 131 has been swapped. Then, in Figure 9 In the ink supply device 100b shown, the ink circulates in the circulation path due to the pressure difference between the pressurizing tank 101 and the pressurizing tank 102.

[0099] First of all, Figure 10 The diagram shows graphs illustrating the pressure and flow rate of ink upstream of the ejector head 123 and downstream of the ejector head 123 when ink is ejected from the ejector head 123, with and without the accumulator 131, and under various conditions including a continuously flowing state and a non-continuously flowing state. Here, the non-continuously flowing state refers to a state in which the ink is not circulated in the circulation path during the ejection of ink from the ejector head 123, but is circulated in the circulation path outside of the ejection period (hereinafter referred to as intermittent flow).

[0100] Figure 10 The graph shown in (a) represents, in time series, the pressure (measured by pressure gauge 115) and flow rate (measured by flow meter 140) of the ink upstream of the ejector head 123, and the pressure (measured by pressure gauge 116) and flow rate (measured by flow meter 141) of the ink downstream of the ejector head 123, under the condition that the accumulator 131 is installed and is in a constantly flowing state. On the other hand, Figure 10 The graph shown in (b) represents, in time series, the ink pressure (measured by pressure gauge 115) and flow rate (measured by flow meter 140) upstream of the ejector head 123, and the ink pressure (measured by pressure gauge 116) and flow rate (measured by flow meter 141) downstream of the ejector head 123, under the condition that no accumulator 131 is installed and the flow is constant. Furthermore, since each graph uses raw data measured by pressure gauges 115, 116 and flow meters 140, 141, the accompanying description contains minor noise. A comparison of the pressure values ​​from both sides clearly shows that… Figure 10 The variation ratio of ink pressure values ​​on the upstream and downstream sides of the ejector head 123 shown in (a) Figure 10 The small variation shown in (b) indicates that the pressure fluctuation caused by the ink ejection from the nozzle 123 is suppressed by the accumulator 131. Furthermore, a comparison of the flow rate values ​​of both devices clearly shows that... Figure 10The variation in ink flow rate value downstream of the ejector head 123 shown in (a) Figure 10 The small variation shown in (b) indicates that the accumulator 131 suppresses the downstream flow rate variation caused by the ink ejection from the ejector head 123. On the other hand, regarding the ink flow rate value upstream of the ejector head 123, as... Figure 10 As shown in (a), no small amplitude fluctuations are observed; the flow rate gradually increases, and from the moment the ejection ends, it does not immediately return to the flow rate before ejection, but rather gradually decreases. Therefore, it is necessary to determine the extent to which the gradual increase in the ink flow rate upstream of the ejector head 123, and the gradual decrease in flow rate from the moment the ejection ends, affects the amount of ink ejected from the ejector head 123. This will be determined in [the following text is missing from the original extract]. Figure 11 and Figure 12 Detailed description is provided.

[0101] Figure 10 The graph shown in (c) represents, in time series, the pressure (measured by pressure gauge 115) and flow rate (measured by flow meter 140) of the ink upstream of the ejector head 123 when ink is ejected from the ejector head 123 under conditions where the accumulator 131 is installed and the flow is not continuous (i.e., intermittent flow). Furthermore, in this case, because the ink does not flow downstream of the ejector head 123 through a valve (not shown) in the ink flow path 204 downstream of the ejector head 123, a graph showing the pressure and flow rate values ​​downstream of the ejector head 123 is not included. On the other hand, Figure 10 The graph shown in (d) is a time series representation of the ink pressure (measured by pressure gauge 115) and flow rate (measured by flow meter 140) upstream of the ejector head 123 when ink is ejected from the ejector head 123 under conditions where the accumulator 131 is not installed and the flow is not continuous (i.e., intermittent flow). A comparison of the pressure values ​​in the graphs clearly shows that... Figure 10 The variation in ink pressure on the downstream side of the ejector head 123 shown in (c) is... Figure 10 The small variation shown in (d) indicates that the accumulator 131 suppresses the pressure fluctuation on the upstream side caused by the ink ejection from the ejector head 123. Furthermore, regarding the ink flow rate value on the upstream side of the ejector head 123, as... Figure 10 As shown in (c), no small amplitudes are observed; the flow rate gradually increases, and from the moment the ejection ends, it is clear that the flow rate does not immediately return to the value before ejection, but rather gradually decreases. Thus, compared to... Figure 10Similar to case (a), it is necessary to determine the extent to which the gradual increase in the ink flow rate value upstream of the ejector head 123, and the gradual decrease in the flow rate value from the moment of ejection end instead of immediately returning to the value before ejection, affects the amount of ink ejected from the ejector head 123. This will be... Figure 11 and Figure 12 Detailed description is provided.

[0102] In addition, Figure 10 The pressure and flow rates of the ink on the upstream side of the ejector head 123 shown in (b) are respectively compared with... Figure 10 By comparing the pressure and flow rates of the ink on the upstream side of the ejector head 123 shown in (d), it can be clearly known that... Figure 10 The variation ratio of ink pressure and flow rate on the upstream side of the ejector head 123 shown in (b) Figure 10 The small variation shown in (d) indicates that the constant flow state suppresses the changes in pressure and flow rate on the upstream side caused by the ink ejection from the nozzle 123.

[0103] exist Figure 11 In the chart shown, as described above, in order to confirm Figure 10 (a) and Figure 10 The effect of the flow rate of the ink on the upstream side of the ejector head 123 shown in (c) on the amount of ink ejected from the ejector head 123 is represented as a time series, dividing the ink ejected from the ejector head 123 into three halves each: the pressure value (measured by pressure gauge 115) and flow rate value (measured by flow meter 140) of the ink on the upstream side of the ejector head 123, and the pressure value (measured by pressure gauge 116) and flow rate value (measured by flow meter 141) of the ink on the downstream side of the ejector head 123. Furthermore, in Figure 11 In, with Figure 10 The conditions shown correspond to whether the accumulator 131 is installed and whether it is always in operation.

[0104] first, Figure 11 The variation ratio of ink pressure values ​​on the upstream and downstream sides of the ejector head 123 shown in (a) Figure 11 The small variation shown in (b) indicates that the pressure fluctuation caused by the ink ejection from the ejector head 123 is suppressed by the accumulator 131. Furthermore, Figure 11 The variation in ink flow rate value downstream of the ejector head 123 shown in (a) Figure 11 The small variation shown in (b) indicates that the accumulator 131 suppresses the variation in downstream flow caused by the ink ejection from the nozzle 123.

[0105] in addition, Figure 11The variation in ink pressure on the upstream side of the ejector head 123 shown in (c) is... Figure 11 The small variation shown in (d) indicates that the pressure variation on the upstream side caused by the ink ejection from the nozzle 123 is suppressed by the accumulator 131.

[0106] in addition, Figure 11 The variation ratio of ink pressure and flow rate on the upstream side of the ejector head 123 shown in (b) Figure 11 The small variation shown in (d) indicates that the constant flow state suppresses the changes in pressure and flow rate on the upstream side caused by the ink ejection from the nozzle 123.

[0107] Furthermore, from Figure 12 (a) and Figure 12 (c) and Figure 12 (b) and Figure 12 As can be seen from the comparison in (d), by providing the accumulator 131, even with rapid pressure fluctuations caused by the ejection of ink from the ejector head 123, the ejection volume of ink from the ejector head 123 remains stable, and it can be inferred that the thixotropic properties of the ink as a non-Newtonian fluid are utilized, maintaining a low viscosity state. Furthermore, from... Figure 12 (b) and Figure 12 As can be seen from the comparison of (d), by setting it to a state of constant flow, even for the sharp pressure changes caused by the ejection of ink from the ejector head 123, it can be known that the amount of ink ejected from the ejector head 123 is stable, and it can be inferred that the thixotropic properties of the ink as a non-Newtonian fluid are utilized, and the low viscosity state is maintained.

[0108] In addition, according to Figures 10-12 The results shown also indicate that the ink used in the ink supply device 100b according to this embodiment absorbs the energy that is the main cause of pressure and flow rate changes. This can be attributed to the fact that the ink is a high-viscosity fluid, thus acting like a brake to changes in pressure and flow rate, and also absorbing the energy of pressure and flow rate changes when subjected to thixotropic shear forces, thus acting like a brake as well.

[0109] Furthermore, by having an accumulator 131 and being in a constantly flowing state, the effects of suppressing the pressure and flow rate fluctuations of the ink caused by the ejection of ink from the ejector head 123, as well as stabilizing the ejection volume, are not only achieved in the ink supply device 100b according to this embodiment, but also in the ink supply devices 100 and 100a according to the first and second embodiments described above.

[0110] As described above, in the ink supply device 100b according to this embodiment, the pressure tank 101 receives air compressed by the high-pressure air supply source 200 and stores ink pressurized by the compressed air. The stored ink is transported to the accumulator 131 side. The pressure tank 102 supplies the stored ink to the pressure tank 101. The regulator 111 depressurizes the compressed air supplied from the high-pressure air supply source 200 to the pressure tank 101 to a first pressure. The regulator 112 depressurizes the compressed air supplied from the high-pressure air supply source 200 to the pressure tank 102 to a second pressure lower than the first pressure. The pump 121 pumps the ink stored in the pressure tank 102 to... The pressurized tank 101 delivers ink, and the ejector head 123 has an internal flow path through which ink supplied from the ink flow path 203 flows, and ejects ink from this internal flow path via a nozzle. The ink flowing out from the internal flow path of the ejector head 123 is delivered to the pressurized tank 102 via the ink flow path 204. An accumulator 131 is disposed in the ink flow path 203 downstream of the pressurized tank 101 and upstream of the ejector head 123, absorbing pressure fluctuations in the ink flowing in the ink flow path 203, thereby forming a circulation path in which the ink circulates in the ink flow path in the sequence of pressurized tank 101, accumulator 131, ejector head 123, pressurized tank 102, and pressurized tank 101. As a result, pressure and flow fluctuations caused by the ejection of ink from the ejector head 123 can be suppressed, thus enabling the stable and long-distance ejection of high-viscosity ink (an example of a liquid).

[0111] [Fourth Implementation Method]

[0112] The ink supply device according to the fourth embodiment will be described focusing on the differences from the ink supply device 100b according to the third embodiment. In this embodiment, the configuration in which an accumulator is also provided on the downstream side of the ejector head 123 will be described.

[0113] Figure 13 The diagram shown is an example of the configuration of the ink supply device according to the fourth embodiment. (Refer to...) Figure 13 The configuration of the ink supply device 100c according to this embodiment will be described.

[0114] like Figure 13As shown, the ink supply device 100c includes a high-pressure air supply source 200 (compressed air supply source), a regulator 111 (first regulator), a pressurization tank 101 (first pressurization tank), a stirring device 103, a regulator 112 (second regulator), a pressurization tank 102 (second pressurization tank), a stirring device 104, a pump 121, a filter 122, a flow meter 140, an accumulator 131 (an example of a first buffering device), a pressure gauge 115, a nozzle 123, a nozzle opening and closing control device 125, an accumulator 132 (an example of a second buffering device), a pressure and flow control device 118 (second control device), and a control device 300b. That is, the configuration of the ink supply device 100c is the same as that of the ink supply device 100b according to the third embodiment described above, except that it includes the accumulator 132.

[0115] Accumulator 132 is located on the ink flow path 204 immediately downstream of the print head 123. It is an accumulator that mitigates pressure fluctuations by absorbing and filling the ink flowing inside it as the pressure increases or decreases. The configuration of accumulator 132 is the same as that of accumulator 131, but the above-described configuration can also be used. Figure 3 The piston pressing mechanism 131-2 shown (an example of the second buffer device) or Figure 4 The auxiliary tank 131-3 (an example of the second damping device) shown is used instead of the accumulator 132. Thus, similar to the second embodiment described above, the damping effect can be applied more evenly to all nozzles of the ejector head 123, and the pressure and flow rate fluctuations caused by the ejection of ink from the ejector head 123 can be suppressed more effectively.

[0116] It should be noted that, in order to reduce pressure loss in the flow path, the accumulator 132 is preferably located as close as possible to the downstream side of the nozzle 123.

[0117] [Fifth Implementation Method]

[0118] The ink supply device according to the fifth embodiment will be described focusing on the differences from the ink supply device 100b according to the third embodiment. In this embodiment, the configuration of providing a flow control valve 142 on the downstream side of the pressurized tank 101 in the ink flow path 203 will be described.

[0119] Figure 14 The diagram shown is an example of the configuration of the ink supply device according to the fifth embodiment. (Refer to...) Figure 14 The configuration of the ink supply device 100d according to this embodiment will be described.

[0120] like Figure 14As shown, the ink supply device 100d includes a high-pressure air supply source 200 (compressed air supply source), a regulator 111 (first regulator), a pressurization tank 101 (first pressurization tank), a stirring device 103, a regulator 112 (second regulator), a pressurization tank 102 (second pressurization tank), a stirring device 104, a pump 121, a flow control valve 142, a filter 122, a flow meter 140, an accumulator 131 (an example of a first buffer device), a pressure gauge 115, a nozzle 123, a nozzle opening and closing control device 125, a pressure and flow control device 118 (second control device, third control device), and a control device 300d. That is, the configuration of the ink supply device 100d is the same as that of the ink supply device 100b according to the third embodiment described above, except that it includes the flow control valve 142.

[0121] The flow control valve 142 is a valve device installed on the ink flow path 203 downstream of the pressurized tank 101 and upstream of the accumulator 131, to control the flow rate of ink flowing from the pressurized tank 101 to the ink flow path 203. The opening degree of the flow control valve 142 is controlled by the pressure flow control device 118.

[0122] The pressure-flow control device 118 receives ink pressure data measured by the pressure gauge 115 and controls the pressure reduction actions of regulators 111 and 112 in a manner that allows the pressure to be arbitrary. Furthermore, the pressure-flow control device 118 is linked to the nozzle opening / closing control device 125, controlling the pressure reduction actions of regulators 111 and 112 based on the ink pressure (ejection pressure) measured by the pressure gauge 115 when the nozzle of the ejector head 123 is not open, thereby enabling stable ink pressure control. At this time, the pressure-flow control device 118 can detect the opening state of the nozzle of the nozzle opening / closing control device 125 via the control device 300d. Additionally, the pressure-flow control device 118 receives ink flow data measured by the flow meter 140 located on the ink flow path 203 downstream of the pressurized tank 101 and upstream of the ejector head 123, and controls the drive time and speed of the pump 121, as well as the opening degree of the flow control valve 142, based on this data.

[0123] The control device 300d is a controller that controls the overall operation of the ink supply device 100d. For example, the control device 300d performs on / off control of the stirring action of the stirring device 103 and the stirring device 104, controls the nozzle opening and closing control device 125, and controls the pressure and flow control device 118.

[0124] As described above, in the ink supply device 100d according to this embodiment, by providing the flow control valve 142, the pressure flow control device 118 stably controls the ejection pressure, thus enabling the adjustment of the pressure reduction performed by the regulator 111 and the regulator 112 to freely adjust the flow rate when the flow rate increases or decreases.

[0125] [Sixth Implementation Method]

[0126] The ink supply device according to the sixth embodiment will be described focusing on the differences from the ink supply device 100d according to the fifth embodiment. In this embodiment, the configuration in which an accumulator is also provided on the downstream side of the ejector head 123 will be described.

[0127] Figure 15 The diagram shown is an example of the configuration of the ink supply device according to the sixth embodiment. (Refer to...) Figure 15 The configuration of the ink supply device 100e according to this embodiment will be described.

[0128] like Figure 15 As shown, the ink supply device 100e includes a high-pressure air supply source 200 (compressed air supply source), a regulator 111 (first regulator), a pressurization tank 101 (first pressurization tank), a stirring device 103, a regulator 112 (second regulator), a pressurization tank 102 (second pressurization tank), a stirring device 104, a pump 121, a flow control valve 142, a filter 122, a flow meter 140, an accumulator 131 (an example of a first buffer device), a pressure gauge 115, a nozzle 123, a nozzle opening and closing control device 125, an accumulator 132 (an example of a second buffer device), a pressure and flow control device 118 (a second control device, a third control device), and a control device 300d. That is, the configuration of the ink supply device 100e is the same as that of the ink supply device 100e according to the fifth embodiment described above, except that it includes the accumulator 132.

[0129] Accumulator 132 is located on the ink flow path 204 immediately downstream of the print head 123. It is an accumulator that mitigates pressure fluctuations by absorbing and filling the ink flowing inside it as the pressure increases or decreases. The configuration of accumulator 132 is the same as that of accumulator 131, but the above-described configuration can also be used. Figure 3 The piston pressing mechanism 131-2 shown (an example of the second buffer device) or Figure 4 The auxiliary tank 131-3 (an example of the second damping device) shown is used instead of the accumulator 132. Thus, similar to the second embodiment described above, the damping effect can be applied more evenly to all nozzles of the ejector head 123, and the pressure and flow rate fluctuations caused by the ejection of ink from the ejector head 123 can be suppressed more effectively.

[0130] It should be noted that, in order to reduce pressure loss in the flow path, the accumulator 132 is preferably located as close as possible to the downstream side of the nozzle 123.

[0131] [Seventh Implementation Method]

[0132] In this embodiment, the configuration of the liquid coating apparatus equipped with the ink supply device 100 described above will be explained.

[0133] (Composition of the liquid coating apparatus)

[0134] Figure 16 The diagram shown is an example of the overall appearance of the liquid coating apparatus according to the seventh embodiment. Figure 17 The diagram shown is an example of the state in which the carriage of the printing device in the liquid coating apparatus according to the seventh embodiment is in a holding position. Figure 18 The diagram shown is an example of the configuration of an ink supply device mounted in the liquid coating apparatus according to the seventh embodiment. (Refer to...) Figures 16-18 The overall configuration of the liquid coating apparatus 1 according to this embodiment will be described. In addition, the configuration of the liquid coating apparatus 1 when it is equipped with the ink supply device 100 described above will be described here, but it is not limited to this, and any one of the ink supply devices 100a to 100e described above may also be used.

[0135] Figure 16 The liquid coating apparatus 1 shown divides a large liquid coating area on a surface such as a road surface into multiple printing areas and moves sequentially to each printing area. It then divides the printing data for printing onto the liquid coating areas into multiple printed images for printing. Furthermore, "printing" refers to the action of forming an image by applying or spraying ink onto a surface. Additionally, in... Figure 17 In order to illustrate the internal structure of the frame portion 11 described later, the following is shown: Figure 17 From the paper's perspective, this is the state after the front panel has been removed. For example... Figure 16 As shown, the liquid coating apparatus 1 includes an ink supply device 100, a frame 11, and a trolley 20.

[0136] In this embodiment, such as Figure 16 and Figure 18 As shown, the ink supply device 100 includes an ink supply mechanism 13, a control device 300, a print head 123, a nozzle opening and closing control device 125, and a pressure gauge 115. Specifically, as... Figure 18 As shown, the ink supply mechanism 13 includes Figure 1The components of the ink supply device 100 shown, excluding the print head 123, pressure gauge 115, nozzle opening / closing control device 125, and control device 300, are as follows: Figure 16 It is disposed on the upper surface of the frame portion 11 as shown.

[0137] The frame 11 can be transported by a trolley 20 and is a device that prints on the mounting surface by scanning a carriage equipped with a print head 123. For example... Figure 16 and Figure 17 As shown, the frame 11 includes four supports 14, a carriage 16, and a holding system 16a. An ink supply mechanism 13 and a control device 300 are provided on the upper surface of the frame 11.

[0138] The brackets 14 are installed at the four corners of the bottom surface of the rectangular frame 11, and are used to support the frame 11 by contacting the mounting surface. In addition, the number of brackets 14 is not limited to four, as long as there are at least three.

[0139] like Figure 18 As shown, the carriage 16 is a component that carries an ink-ejecting head 123, a pressure gauge 115, and a nozzle opening / closing control device 125, and performs scanning in the main scanning direction and the sub-scanning direction via a moving mechanism described later. The scanning of the carriage 16 is controlled by the control device 300. Alternatively, at least one of the pressure gauge 115 and the nozzle opening / closing control device 125 may also be included in the ink supply mechanism 13.

[0140] The maintenance system 16a is a mechanism for maintaining the nozzle surface of the spray head 123 mounted on the carriage 16, such as cleaning. For example, Figure 17 As shown, when the carriage 16 is moved to the holding position 30, the control device 300 performs a holding process through the holding system 16a.

[0141] The trolley 20 is a transport device used to move the frame 11 to the printing area by lifting it from its bottom surface. For example... Figure 16 As shown, the trolley 20 has a trolley frame 21, a lifting device 22, a lifting device 23, a front wheel 24, a rear wheel 25, and a handle 26.

[0142] The trolley frame 21 is a frame component that forms a rectangle and supports the frame part 11 from the bottom when the frame part 11 is raised or lowered.

[0143] The lifting device 22 is a part that supports the handle part 26 side (rear side) of the frame part 11 and raises and lowers the frame part 11.

[0144] The lifting device 23 is a part that supports the handle part 26 of the frame part 11 on the opposite side (front side) and raises and lowers the frame part 11.

[0145] The front wheel 24 and the rear wheel 25 are wheels used to move the trolley 20 forward, backward, left, and right.

[0146] The handle 26 is a handle component installed on the rear side of the trolley 20 and held by the user (operator). By holding the handle 26, the user can move the trolley 20 freely in all directions.

[0147] (The composition of the carriage's moving mechanism)

[0148] Figure 19 The diagram shown is an example of the configuration of the moving mechanism of the carriage of the liquid coating apparatus according to the seventh embodiment. (Refer to...) Figure 19 The configuration of the moving mechanism of the carriage 16 used for scanning the liquid coating apparatus 1 according to this embodiment will be described.

[0149] like Figure 19 As shown, the frame 11 serves as a moving mechanism for scanning the carriage 16. The printing apparatus 11 includes a frame 11a, a main scanning guide 17, a main scanning motor 17a, a secondary scanning guide 18, a secondary scanning motor 18a, and a timing belt 18b. This moving mechanism is supported by four supports 15 located in the frame 11a, which forms the periphery of the bottom surface of the printing apparatus body 11.

[0150] Frame 11a is a frame component that forms the four sides of the bottom surface of frame part 11.

[0151] The main scanning guide 17 is in Figure 19 The extended arrangement shown in the main scanning direction supports the carriage 16 as a guide member capable of sliding and moving in the main scanning direction.

[0152] The main scanning motor 17a is a motor used to move the carriage 16 back and forth along the main scanning guide 17 in the main scanning direction.

[0153] Sub-scanning guide 18 is set along the Figure 19 On the frame 11a extending in the sub-scanning direction shown, there is a guide component that can slide along the sub-scanning direction to support the main scan guide 17. For example... Figure 19 As shown, the sub-scanning guides 18 are respectively disposed on two frames 11a extending in opposite directions along the sub-scanning direction to support the vicinity of the end of the main scanning guide 17 extending in the main scanning direction.

[0154] The auxiliary scanning motor 18a is a motor used to move the main scanning guide 17 back and forth along the auxiliary scanning guide 18 in the auxiliary scanning direction. In this case, the synchronous belt 18b mounted on the pulley rotated by the auxiliary scanning motor 18a and driven by the pulley is driven by the rotation of the auxiliary scanning motor 18a, thereby moving the main scanning guide 17 back and forth in the auxiliary scanning direction.

[0155] In this way, the carriage 16 equipped with the jet head 123 can move freely along the main scanning direction and the sub-scanning direction on the surface surrounded by the four frames 11a.

[0156] With the above configuration, a liquid coating apparatus 1 can be obtained that can stably and far spray high-viscosity liquid.

[0157] The present invention is described below.

[0158] <1> A liquid supply device is characterized by comprising: a pressure tank supplied with compressed air from a compressed air supply source and storing liquid pressurized by the compressed air; a conveying unit conveying the liquid stored in the pressure tank to a liquid flow path; a nozzle having an internal flow path through which liquid conveyed from the liquid flow path flows and spraying liquid from the internal flow path via a nozzle; and a first mitigation device disposed in the liquid flow path downstream of the pressure tank and upstream of the nozzle, absorbing pressure fluctuations of the liquid flowing in the liquid flow path, and forming a circulation path in which the liquid circulates in the liquid flow path in the order of the pressure tank, the first mitigation device, the nozzle, and the pressure tank, wherein the conveying unit circulates the liquid in the circulation path.

[0159] <2> according to <1> The liquid supply device is characterized in that the conveying unit circulates the liquid in the circulation path both when the spray head sprays liquid and when it does not spray liquid.

[0160] <3> according to <1> or <2> The liquid supply device is characterized in that: the conveying unit is a pump, which is disposed in the liquid flow path on the downstream side of the pressurizing tank and the upstream side of the first buffering device, and pressurizes the liquid in the pressurizing tank toward the first buffering device and delivers it to the liquid flow path.

[0161] <4> according to <3> The liquid supply device is characterized in that it further comprises: a pressure gauge disposed in the liquid flow path downstream of the first buffer device and upstream of the injection head, for measuring the pressure of the liquid flowing in the liquid flow path; and a first control device for controlling the rotational speed of the pump so that the pressure measured by the pressure gauge becomes a predetermined value.

[0162] <5> according to <1> or <2> The liquid supply device is characterized in that: the pressurizing tank is composed of a first pressurizing tank and a second pressurizing tank, the first pressurizing tank transports the accumulated liquid to one side of the first buffering device through the conveying unit, and the second pressurizing tank supplies the accumulated liquid to the first pressurizing tank.

[0163] <6> according to <5> The liquid supply device is characterized in that it further comprises: a first regulator that reduces the pressure of the compressed air supplied from the compressed air supply source to the first pressure tank to a first pressure; a second regulator that reduces the pressure of the compressed air supplied from the compressed air supply source to the second pressure tank to a second pressure lower than the first pressure; and a pump that delivers the liquid stored in the second pressure tank to the first pressure tank.

[0164] <7> according to <6> The liquid supply device is characterized in that: the liquid flowing out from the internal flow path of the nozzle is transported to the second pressurized tank via the liquid flow path, and the conveying unit is composed of the first pressurized tank, the second pressurized tank, the first regulator, the second regulator and the pump, and transports the liquid accumulated in the first pressurized tank to the liquid flow path.

[0165] <8> according to <6> or <7> The liquid supply device is characterized in that it further comprises: a pressure gauge disposed in the liquid flow path downstream of the first buffer device and upstream of the injection head, for measuring the pressure of the liquid flowing in the liquid flow path; and a second control device for controlling the pressure reduction action of the first regulator and the second regulator so that the pressure measured by the pressure gauge becomes a predetermined value.

[0166] <9> according to <5> to <7> The liquid supply device according to any one of the following methods is characterized in that it further comprises a flow control valve, which is disposed in the liquid flow path downstream of the first pressurizing tank and upstream of the first mitigation device, and controls the flow rate of the liquid in the liquid flow path.

[0167] <10> according to <9> The liquid supply device is characterized in that it further comprises: a flow meter disposed in the liquid flow path downstream of the first pressurized tank and upstream of the injection head, for measuring the flow rate of the liquid flowing in the liquid flow path; and a third control device for controlling the opening degree of the flow control valve based on the flow rate measured by the flow meter.

[0168] <11> according to <1> ~ <10> The liquid supply device according to any one of the following is characterized in that: it further comprises a second mitigation device, which is disposed in the liquid flow path downstream of the injection head and upstream of the pressurization tank, to absorb pressure fluctuations of the liquid flowing in the liquid flow path.

[0169] <12> according to <1> to <11> The liquid supply device according to any one of the following methods is characterized in that the first mitigation device is a piston-pressing mechanism having an accumulator, a secondary tank, or a buffer.

[0170] <13> according to <11> The liquid supply device is characterized in that the second buffering device is a piston pressing mechanism having an accumulator, a secondary tank, or a buffer.

[0171] <14> according to <1> ~ <13> The liquid supply device according to any one of the following descriptions is characterized in that: the inkjet head is an inkjet head that opens and closes the nozzle by means of an actuator operating a needle.

[0172] <15> according to <3> , <6> or <7> The liquid supply device is characterized in that the pump is a diaphragm pump.

[0173] <14> according to <1> ~ <15> The liquid supply device according to any one of the following descriptions is characterized in that: the pressurized tank is supplied with air compressed to a pressure above atmospheric pressure by the compressed air supply source.

[0174] <17> A liquid coating apparatus, characterized by comprising: a liquid supply device for spraying liquid onto a surface; a transport device for moving the liquid supply device; and a support member for supporting the liquid supply device. The liquid supply device includes: a pressure tank supplied with compressed air from a compressed air supply source and storing liquid pressurized by the compressed air; a transport unit for transporting the liquid stored in the pressure tank to a liquid flow path; a spray head having an internal flow path through which liquid transported from the liquid flow path flows and spraying liquid from the internal flow path via a nozzle; and a first buffering device disposed in the liquid flow path downstream of the pressure tank and upstream of the spray head, absorbing pressure fluctuations of the liquid flowing in the liquid flow path and forming a circulation path in which the liquid circulates in the liquid flow path in the order of the pressure tank, the first buffering device, the spray head, and the pressure tank, and the transport unit circulates the liquid in the circulation path.

Claims

1. A liquid supply device, characterized in that... include: A pressurized tank, which is supplied with compressed air from a compressed air supply source and stores liquid pressurized by the compressed air; A delivery unit that delivers the liquid stored in the pressurized tank to the liquid flow path; A spray head having an internal flow path through which liquid supplied from the liquid flow path passes, and liquid is sprayed out from the internal flow path via a nozzle, and A first mitigation device is disposed in the liquid flow path downstream of the pressurized tank and upstream of the injection head, absorbing pressure fluctuations of the liquid flowing in the liquid flow path. This constitutes a circulation path in which the liquid circulates within the liquid flow path in the order of the pressurized tank, the first buffer device, the injection head, and the pressurized tank. The delivery unit circulates the liquid in the circulation path. The pressurization tank consists of a first pressurization tank and a second pressurization tank. The first pressurization tank transports the accumulated liquid to one side of the first buffer device through the conveying unit, and the second pressurization tank supplies the accumulated liquid to the first pressurization tank. The liquid supply device further includes: A first regulator reduces the pressure of the compressed air supplied from the compressed air supply source to the first pressurized tank to a first pressure. A second regulator reduces the pressure of the compressed air supplied from the compressed air supply source to the second pressurized tank to a second pressure lower than the first pressure. A pump that delivers the liquid stored in the second pressurized tank to the first pressurized tank.

2. The liquid supply device according to claim 1, characterized in that: The delivery unit circulates the liquid in the circulation path both when the nozzle is spraying liquid and when it is not spraying liquid.

3. The liquid supply device according to claim 1 or 2, characterized in that: The delivery unit is a pump located in the liquid flow path downstream of the pressurization tank and upstream of the first buffer device, and pumps the liquid in the pressurization tank toward the first buffer device into the liquid flow path.

4. The liquid supply device according to claim 3, characterized in that, Also includes: A pressure gauge, disposed downstream of the first mitigation device and upstream of the injection head, in the liquid flow path, measures the pressure of the liquid flowing in the liquid flow path, and A first control device controls the rotational speed of the pump so that the pressure measured by the pressure gauge becomes a predetermined value.

5. The liquid supply device according to claim 1, characterized in that: The liquid flowing out from the internal flow path of the nozzle is transported to the second pressurized tank via the liquid flow path. The delivery unit delivers the liquid stored in the first pressurized tank to the liquid flow path.

6. The liquid supply device according to claim 1, characterized in that, Also includes: A pressure gauge, disposed downstream of the first mitigation device and upstream of the injection head, in the liquid flow path, measures the pressure of the liquid flowing in the liquid flow path, and A second control device controls the pressure reduction action of the first regulator and the second regulator to make the pressure measured by the pressure gauge reach a predetermined value.

7. The liquid supply device according to claim 1, characterized in that: It also includes a flow control valve, which is located in the liquid flow path downstream of the first pressurizing tank and upstream of the first mitigation device, and controls the flow rate of the liquid in the liquid flow path.

8. The liquid supply device according to claim 7, characterized in that, Also includes: A flow meter, installed in the liquid flow path downstream of the first pressurized tank and upstream of the injection head, measures the flow rate of the liquid flowing in the liquid flow path. A third control device controls the opening of the flow control valve based on the flow rate measured by the flow meter.

9. The liquid supply device according to claim 1 or 2, characterized in that: It also includes a second mitigation device disposed in the liquid flow path downstream of the nozzle and upstream of the pressurized tank, which absorbs pressure fluctuations of the liquid flowing in the liquid flow path.

10. The liquid supply device according to claim 1 or 2, characterized in that: The first mitigation device is an accumulator, a secondary tank, or a piston-pressing mechanism with a buffer.

11. The liquid supply device according to claim 9, characterized in that: The second mitigation device is an accumulator, a secondary tank, or a piston-depressing mechanism with a buffer.

12. The liquid supply device according to claim 1 or 2, characterized in that: The printhead is an inkjet printhead that opens and closes the nozzle by operating a needle with an actuator.

13. The liquid supply device according to claim 3, characterized in that: The pump is a diaphragm pump.

14. The liquid supply device according to claim 1 or 2, characterized in that: The pressurized tank is supplied with air compressed to a pressure above atmospheric pressure by the compressed air supply source.

15. A liquid coating apparatus, characterized in that... include: A liquid supply device that sprays liquid onto the installation surface; A conveying device that enables the liquid supply device to move, and Supporting component that supports the liquid supply device The liquid supply device includes: A pressurized tank, which is supplied with compressed air from a compressed air supply source and stores liquid pressurized by the compressed air; A delivery unit that delivers the liquid stored in the pressurized tank to the liquid flow path; A spray head having an internal flow path through which liquid supplied from the liquid flow path passes, and liquid is sprayed out from the internal flow path via a nozzle, and A first mitigation device is disposed in the liquid flow path downstream of the pressurized tank and upstream of the injection head, absorbing pressure fluctuations of the liquid flowing in the liquid flow path. This constitutes a circulation path in which the liquid circulates within the liquid flow path in the order of the pressurized tank, the first buffer device, the injection head, and the pressurized tank. The delivery unit circulates the liquid in the circulation path. The pressurization tank consists of a first pressurization tank and a second pressurization tank. The first pressurization tank transports the accumulated liquid to one side of the first buffer device through the conveying unit, and the second pressurization tank supplies the accumulated liquid to the first pressurization tank. The liquid supply device further includes: A first regulator reduces the pressure of the compressed air supplied from the compressed air supply source to the first pressurized tank to a first pressure. A second regulator reduces the pressure of the compressed air supplied from the compressed air supply source to the second pressurized tank to a second pressure lower than the first pressure. A pump that delivers the liquid stored in the second pressurized tank to the first pressurized tank.

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