JP2006062330A - Discharge head device, fluid discharge device, and fluid discharge method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a pressure on a nozzle surface of a discharge head caused by a sudden pressure fluctuation in a sub tank when a sub tank is depressurized and a negative pressure is applied to the discharge head in a state where the discharge head and the sub tank communicate with each other. Avoid breaking the meniscus.
SOLUTION: A negative pressure arrival speed adjusting unit 20 for controlling a speed at which the sub tank 13 reaches a specified negative pressure is provided between the sub tank 13 and a negative pressure generating unit 19 for reducing the pressure of the sub tank 13.
[Selection] Figure 1

Description

  The present invention relates to a fluid ejection apparatus that performs drawing by ejecting a fluid ejection material onto a medium, such as an inkjet printer or a large-scale production apparatus using inkjet technology. More specifically, a discharge head device that employs a negative pressure generating system that applies a negative pressure to the discharge head in order to prevent leakage of discharge material from the discharge head that discharges fluid, a fluid discharge device equipped with the discharge head, and The present invention relates to a fluid discharge method.

  Conventionally, in order to prevent the discharge material from leaking from the discharge head, the discharge head is controlled to a negative pressure. In this way, as a negative pressure generation system for making the discharge head negative pressure, a tank in which a porous sponge is impregnated with a discharge material is directly connected to the discharge head, and a negative pressure is generated using a capillary phenomenon. For example, as disclosed in Japanese Patent Application Laid-Open No. H10-133707, a mainstream method is to attach a tension spring to a shrinkable ink bag and generate a negative pressure using a force by which the spring expands the ink bag. It has been.

In addition, in a large fluid discharge device, there is also a wide range of methods in which a tank of discharge material is installed outside the carriage on which the discharge head is movably mounted, and negative pressure is generated by utilizing the water head difference between the discharge head and the tank. It is used.
JP 2003-266734 A (publication date: September 24, 2003)

  However, when considering application to a large-scale fluid discharge device, in the method using the capillary phenomenon, the water head difference with respect to the discharge head varies greatly depending on the amount of discharge material in the tank. A stable negative pressure cannot be secured. For example, if the remaining amount of the discharge material is too large, an excessive positive pressure may be applied to the discharge head and the discharge material may leak from the discharge head. On the other hand, if the remaining amount of the discharge material is too small, an excessive negative pressure is applied to the discharge head, the meniscus formed on the nozzle (discharge hole) surface of the discharge head is destroyed, and air is mixed from the nozzle. There is a risk of non-ejection.

  Further, in the technique described in Patent Document 1, there is a risk that the spring attached to the sub tank vibrates when the carriage moves and the proper negative pressure cannot be maintained. In addition, a decrease in the spring constant with time is expected, and as a result, a proper negative pressure cannot be maintained over a long period of time, and there is a possibility that periodic component replacement is required. Further, when the remaining amount of ink in the sub tank is extremely reduced, the internal pressure of the sub tank becomes an excessive negative pressure, and as a result of air being sucked from the discharge head, non-ejection may occur.

  In addition, in the method of installing a tank outside the carriage, which is used in large fluid discharge devices, the tube piping of the discharge material supply system from the tank to the discharge head is complicated, and the discharge material is also filled in the tube. There is a problem that the consumption of the discharge material is increased as compared with the case where a tank is installed in the vicinity of the discharge head.

  Therefore, a small-capacity bag-shaped sub tank that supplies the discharge material necessary for drawing to the discharge head, and a large capacity that supplies the discharge material to the sub tank when the remaining amount of the discharge material in the sub tank is insufficient. In the discharge material supply system composed of the main tank, the sub tank and the main tank are not normally in communication, and the sub tank is not affected by the head difference with the discharge head when the tank is full and when the tank is empty. The difference in liquid level can be made as small as possible, and by setting the internal pressure of the sub tank to negative pressure by the negative pressure generating means attached to the sub tank, a stable negative pressure can always be secured for the discharge head. Configuration is conceivable.

  However, the ink supply system having such a configuration is also set by the pressure generation system of another system when a pressure generation system of another system other than the negative pressure generation means is connected to the sub tank. When the pressure applied to the discharge head is switched from the pressure to the set pressure by the negative pressure generation system, a sudden pressure fluctuation occurs to destroy the meniscus formed on the nozzle surface of the discharge head, resulting in the nozzle The air may be sucked from the ink, which may cause ink non-ejection.

  In addition, regardless of the pressure setting by the separate pressure generation system, the same problem may occur when the power is turned on from the power-off state and negative pressure is generated by the negative pressure generation system. .

  In order to solve the above problems, an ejection head device according to the present invention includes an ejection head that ejects an ejection material onto a medium, a subtank that stores ejection material supplied to the ejection head, and an ejection material that is supplied to the subtank. A negative pressure generating means connected to the sub tank and depressurizing the sub tank to make the pressure of the discharge head a predetermined negative pressure, and the negative pressure generating means is a pressure of the discharge head. And a negative pressure arrival speed adjusting means for controlling an arrival speed until the pressure reaches a predetermined negative pressure.

  According to this configuration, the negative pressure arrival speed adjustment unit reaches the negative pressure determined by the pressure of the ejection head when the pressure of the ejection head is shifted to the negative pressure required for ink ejection by the negative pressure generating unit. Therefore, the pressure of the discharge head does not change rapidly, the meniscus formed on the nozzle surface of the discharge head is not destroyed, and a state where ink can be discharged can be created. it can.

  In the ejection head device of the present invention, the sub tank may be connected to pressure generating means for setting the pressure of the sub tank to a pressure different from that of the negative pressure generating means. In the configuration where another pressure generating means is connected to the sub-tank, especially when the one that generates positive pressure is connected to the discharge head, the pressure of the discharge head is necessary for ink discharge by the negative pressure generating means. In shifting to a predetermined negative pressure, a sudden change in the pressure of the discharge head is very likely to occur, and the meniscus is likely to be destroyed. By adopting the configuration of the present invention, a state in which ink discharge is possible is created. be able to.

  The negative pressure generation means includes a vacuum pump as a negative pressure generation source and a regulator that adjusts the negative pressure generated by the vacuum pump to a predetermined negative pressure, or a negative pressure generation as a negative pressure generation source. And a regulator that adjusts the negative pressure generated by the negative pressure generator to a predetermined negative pressure.

  By using a vacuum pump as a negative pressure generation source, it is possible to generate a negative pressure with a relatively simple configuration without requiring an external input as compared with the case of using a vacuum generator. On the other hand, when a vacuum generator with a built-in electromagnetic switching valve is used as a negative pressure generation source, space can be saved compared to the case where a vacuum generation pump is used, and a switching valve for negative pressure generation control is provided. Since it is not necessary to provide a route on the way, cost reduction and space saving can be achieved.

  In the ejection head device of the present invention, the negative pressure arrival speed adjusting means may be a speed controller, and may be arranged between the sub tank and the negative pressure generating means.

  By using a speed controller as a negative pressure arrival speed adjustment means to control the arrival speed to the specified negative pressure, it is possible to control the arrival speed with a relatively simple and inexpensive configuration without requiring complex control. Can be adjusted.

  In the discharge head device of the present invention, the negative pressure arrival speed adjusting means is composed of an electropneumatic regulator, and is arranged between the sub tank and the negative pressure generating means, and the predetermined negative pressure is set to a plurality of set pressures. And the negative pressure attainment speed adjusting means is composed of a mass flow controller, and the sub tank and the negative pressure are adjusted by increasing the set pressure stepwise. It can also be set as the structure arrange | positioned between pressure generation means.

  In order to solve the above-described problems, the fluid ejection device of the present invention is characterized by including the ejection head device of the present invention, so that the meniscus in the ejection head is not destroyed and the ink can be ejected. It is possible to realize a fluid ejection device that can be stably produced, and thus can perform stable drawing.

  In order to solve the above-described problems, the fluid discharge method of the present invention reduces the pressure of the discharge head that discharges the discharge material to the medium by the negative pressure generating means of the tank that supplies the discharge material to the discharge head. In the fluid discharge method for controlling the negative pressure determined in this way, when the pressure of the discharge head is reached from the pressure different from the predetermined negative pressure to the predetermined negative pressure, the reaching speed is controlled. It is characterized by.

  As a result, when the pressure of the discharge head is shifted to the negative pressure required for ink discharge by the negative pressure generating means, the arrival speed until the negative pressure of the discharge head reaches the predetermined negative pressure is controlled. The pressure of the head does not change abruptly, the meniscus formed on the nozzle surface of the ejection head is not destroyed, and a state where ink can be ejected can be created.

  As described above, the discharge head device or the fluid discharge device of the present invention is configured to adjust the negative pressure arrival speed for controlling the arrival speed until the negative pressure generating means causes the pressure of the discharge head to reach the predetermined negative pressure. Therefore, the pressure of the discharge head does not change abruptly, the meniscus formed on the nozzle surface of the discharge head is not destroyed, and the ink can be discharged. As a result, a fluid ejection device capable of stable drawing can be realized.

  In the fluid discharge method of the present invention, as described above, the pressure of the discharge head that discharges the discharge material to the medium is determined by reducing the tank that supplies the discharge material to the discharge head by the negative pressure generating means. In the fluid discharge method for controlling to a predetermined negative pressure, the arrival speed is controlled when the pressure of the discharge head is reached from the pressure different from the predetermined negative pressure to the predetermined negative pressure. The pressure of the ink does not change abruptly, the meniscus formed on the nozzle surface of the ejection head is not destroyed, and it is possible to create a state where ink can be ejected, thereby enabling stable drawing.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 8 as follows.

  FIG. 1 is a schematic diagram showing an outline of a main configuration of a discharge head device 1 mounted on a fluid discharge device such as an ink jet device which is one embodiment of the present invention.

  In the ejection head device 1, the ejection head 11 is mounted on a carriage 16 that reciprocates with respect to the recording surface of the recording medium. The ejection head 11 scans the recording surface of the recording medium 10 in parallel with the movement of the carriage 16 and adjusts the amount of the ink 12 that is an ejection material during the scanning, thereby ejecting the recording medium 10 for drawing. Is what you do.

A sub tank 13 is connected to the ejection head 11 via an ink tube 24 described later. The sub tank 13 stores the ink 12 supplied to the ejection head 11. Here, the sub tank 13 is formed of a bag-like member having stretchability, and has a high airtightness and does not expand and contract. It is stored in the tank box 17. Although details will be described later, by controlling the atmospheric pressure in the tank box 17, a negative pressure for the discharge head 11 is generated in the sub tank 13 or a positive pressure for the main tank 14 is generated. Further, as described above, it is preferable that the sub-tank 13 has a configuration in which the difference in liquid level between the tank full and the tank empty can be made as small as possible so as not to be affected by the water head difference with the discharge head 11. Therefore, here, the capacity of the sub tank 13 is small and the capacity of the main tank 14 is larger than this. The main tank 14 is connected to the sub tank 13 via the ink pipe 24. The main tank 14 stores the ink 12 supplied to the sub tank 13. The sub tank 13 and the main tank 14 (more precisely, the sub tank 13 and the main tank 14 stored in the tank box 17) are mounted on the carriage 16 together with the discharge head 11, and move together with the discharge head 11. It is the composition to do.

  On the carriage 16, the sub tank 13 is installed at a position higher than the ejection head 11, and the main tank 14 is installed at a position higher than the sub tank 13. By setting such an installation position, the supply of the ink 12 from the main tank 14 to the sub tank 13 and the supply of the ink 12 from the sub tank 13 to the ejection head 11 are both performed using the water head difference.

  The ink pipe 24 connecting the discharge head 11, the sub tank 13, and the main tank 14 is composed of branch pipes 24a, 24b, and 24c branched in three directions, and a three-way switching valve 15 is disposed at the branch point. The three-way switching valve 15 is a solenoid valve having a common port COM, a normally open port NO, and a normally closed port NC. When no voltage force is applied, the common port COM port and the normally open port NO communicate with each other. When a predetermined voltage force (for example, 24 V) is applied, the common port COM and the normally closed port NC communicate with each other.

  The normally closed port NC has one end connected to the other end of the branch pipe 24a connected to the discharge head 11, and the common port COM is connected to the other end of the branch pipe 24b connected to the sub tank 13. . The normally open port NO is connected to the other end of the branch pipe 24 c connected at one end to the main tank 14.

  When the power is cut off or when a predetermined voltage force is not applied to the switching valve 15, the sub tank 13 and the main tank 14 communicate with each other and the ink 12 is supplied to the sub tank 13. On the other hand, when a predetermined voltage force is applied to the switching valve 15, the ejection head 11 and the sub tank 13 communicate with each other, and ink is supplied to the ejection head 11. In any case, by providing the switching valve 15 that selectively switches the connection destination of the sub tank 13 at the branch point, the discharge head 11 and the main tank 14 do not communicate with each other. Ink leakage from the discharge head 11 is not caused by the pressurized component caused by the water head difference between the main tank 14 and the main tank 14.

  The three-way switching valve 15 is preferably used for a chemical solution, and the liquid contact portion and the connection portion with the ink tube 24 are preferably formed of Teflon (registered trademark) resin having high chemical resistance. The ink tube 24 is preferably formed of a Teflon (registered trademark) tube and / or a Kalrez tube.

  On the other hand, in the tank box 17 storing the sub tank 13, a positive pressure generating part (positive pressure generating means) 18 and a negative pressure generating part (negative pressure generating means) 19 provided outside the carriage 16 are separately bent. The pipes 26 and 27 are connected. The positive pressure generator 18 generates a positive pressure for the main tank 14 in the sub tank 13 by pressurizing the inside of the tank box 17 via the flexible pipe 26. On the other hand, the negative pressure generating unit 19 generates a negative pressure for the discharge head 11 in the sub tank 13 by reducing the pressure in the tank box 17 via the flexible pipe 27. The positive pressure generator 18 and the negative pressure generator 19 do not operate simultaneously.

  The flexible pipe 27 connecting the negative pressure generating unit 19 and the tank box 17 has a negative pressure arrival speed adjusting unit (negative pressure arrival speed adjustment) for adjusting the speed until the inside of the tank box 17 reaches the specified pressure. Means) 20 is provided. As will be described in detail later, by adjusting the speed of the pressure change in the tank box 17 by such a negative pressure arrival speed adjusting unit 20, a sudden pressure fluctuation in the discharge head 11 is suppressed, and air is sucked in. Ink ejection failure can be effectively avoided.

  The negative pressure arrival speed adjustment unit 20, the positive pressure generation unit 18, the negative pressure generation unit 19, and the three-way switching valve 15 are controlled by a control unit 25 including a CPU, and the negative pressure arrival speed adjustment unit 20. The control unit 25 constitutes a negative pressure arrival speed adjusting means, the positive pressure generating part 18 and the control part 25 constitute positive pressure generating means, and the negative pressure generating part 19 and the control part 25 are negative. A pressure generating means is configured.

  As described above, the negative pressure generator 19 generates a negative pressure with respect to the ejection head 11, but the control unit 25 applies the ejection head 11 with respect to the ejection head 11 when ejecting the ink 12 from the ejection head 11. Except during a part of the maintenance sequence, the negative pressure generator 19 is operated to apply the predetermined voltage force to the switching valve 15 to connect the sub-tank 13 to the tank box 17. The inside is depressurized. As a result, a negative pressure that can prevent ink leakage from the discharge head 11 due to a water head difference between the discharge head 11 and the sub tank 13 is generated in the sub tank 13, and this negative pressure is applied to the discharge head 11. Ink leakage does not occur.

  This negative pressure will be described in more detail. In the ejection head device 1 of the present embodiment, the water head difference between the ejection head 11 and the sub tank 13 is 10 cm. Since the head difference of 10 cm generates a pressure of 1 kPa, if the pressure applied to the sub tank 13, that is, the pressure in the tank box 17 is equal to the atmospheric pressure and the carriage 16 is stationary, A pressure 1 kPa larger than the atmospheric pressure is applied. That is, the ejection head 11 has a positive pressure of 1 kPa with respect to the outside. This 1 kPa causes ink leakage. Further, while the carriage 16 is moving, the ejection head 11 may be at a higher positive pressure due to acceleration / deceleration of the carriage 16.

  Therefore, in the ejection head device 1, the negative pressure generator 19 generates a negative pressure in the sub tank 13, thereby canceling out the positive pressure due to the water head difference and the acceleration / deceleration of the carriage 16. Specifically, the negative pressure generating unit 19 reduces the pressure inside the highly airtight tank box 17. The pressure at the time of depressurization is a pressure that takes into account the pressure generated by the water head difference between the sub tank 13 and the ejection head 11 and the pressure accompanying acceleration / deceleration during scanning of the carriage 16. In the ejection head device 1, since the pressure due to the water head difference is 1 kPa, the pressure is further reduced by 2 kPa added by 1 kPa in consideration of the pressure change accompanying the movement of the carriage 16. Thereby, the discharge head 11 can overcome the water head difference from the sub tank 13 and the pressure change accompanying the acceleration / deceleration of the carriage 16, and can stably maintain the discharge head at a negative pressure.

  An example of the configuration of the negative pressure generator 19 is shown in FIG. The negative pressure generator 19A shown in FIG. 2 generates a negative pressure by a vacuum pump 21 as a negative pressure source, and the generated negative pressure is transferred between the vacuum pump 21 and the tank box 17 in which the sub tank 13 is stored. A desired pressure is adjusted by a connected regulator 22. Further, between the vacuum pump 21 and the tank box 17, a two-way switching valve 23 that controls whether or not the tank box 17 is decompressed is disposed. Under the control of the control unit 25, the switching valve 23 does not depressurize the tank box 17 when the power is shut off or in a state where the predetermined voltage force is not applied, and when the predetermined voltage force is applied, 17 is depressurized. In the drawing, the switching valve 23 is arranged between the regulator 22 and the tank box 17, but of course, the switching valve 23 may be provided between the regulator 22 and the vacuum pump 21.

  FIG. 3 shows another configuration example of the negative pressure generator 19. The negative pressure generator 19B generates a negative pressure by using a vacuum generator 30 that generates a vacuum by supplying compressed air as a negative pressure generation source, and the vacuum pump 21 and the sub tank 13 store the generated negative pressure. The pressure is adjusted to a desired pressure by a regulator 22 connected to the tank box 17. The control of whether or not the tank box 17 is depressurized by the control unit 25 is performed by an electromagnetic switching valve built in the vacuum generator 30, and when the power is shut off or when a predetermined voltage force is not applied. When a predetermined voltage force is applied without depressurizing the tank box 17, the tank box 17 is depressurized. Instead of controlling whether or not the tank box 17 is depressurized by the electromagnetic switching valve built in the vacuum generator 30, the electromagnetic switching valve of the vacuum generator 30 does not function (set to be normally open), Two switching valves may be connected between the regulator 22 and the tank box 17 or between the regulator 22 and the vacuum generator 30 in the same manner as the negative pressure generator 19A of FIG.

  By using the vacuum pump 21 as a negative pressure generating source, it is possible to generate a negative pressure with a relatively simple configuration without requiring an external input as compared with the case where the vacuum generator 30 is used. On the other hand, when the vacuum generator 30 having a built-in electromagnetic switching valve is used as the negative pressure generation source, space can be saved as compared with the case where the vacuum pump 21 is used, and the switching valve 23 for negative pressure generation control. Since it is not necessary to provide a route on the way, cost reduction and space saving can be achieved.

  On the other hand, the positive pressure generator 18 is used to return excess ink in the sub tank 13 to the main tank 14. When the applied voltage force of the switching valve 15 is interrupted and the sub tank 13 and the main tank 14 communicate with each other, the ink 12 is supplied from the main tank 14 to the sub tank 13 due to a water head difference, and the sub tank 13 is filled. However, at this time, if the ejection head 11 and the sub tank 13 communicate with each other while the amount of ink in the sub tank 13 is excessive, an excessive positive pressure is applied to the ejection head 11, and the nozzle surface of the ejection head 11 Ink leakage or abnormal ink discharge occurs.

  Therefore, the control unit 25 activates the positive pressure generation unit 18 to pressurize the sub tank 13 in a state where the sub tank 13 is full, thereby partially (a predetermined amount) of the ink 12 in the sub tank 13 to the main tank 14. )return. Thereby, it is possible to avoid ink leakage from the nozzle surface of the ejection head 11 and abnormal ink ejection due to an excessive amount of ink in the sub tank 13.

  The positive pressure generator 18 is used for discharging the ink 12 from the nozzle surface of the ejection head 11. If air or dust accumulates in the nozzles of the ejection head 11, non-ejection of the ink 12 and landing deviation on the recording medium 10 occur. In order to avoid such a problem, a recovery operation for discharging air and dust in the nozzles of the ejection head 11 is necessary. In the recovery operation, the control unit 25 stops the depressurization operation of the sub tank 13 by the negative pressure generating unit 19, and the switching valve 15 keeps the state where the discharge head 11 and the sub tank 13 are connected while the voltage force is applied. Here, the sub tank 13 is pressurized by the positive pressure generator 18. Thereby, ink is discharged from the nozzles of the discharge head 11, and air and dust in the nozzles can be discharged simultaneously.

  By the way, in the above configuration, the internal pressure of the sub tank 13 is changed by the positive pressure generator 18 and the negative pressure generator 19 in accordance with the drawing process and the other processes. When returning from other pressures to the specified negative pressure, which is a predetermined negative pressure set at the time of ejection or other standby, controlling the arrival speed causes the ink 12 to be ejected normally and stably from the ejection head 11. It turned out to be very important above. This is because when the sub-tank 13 is returned to the specified negative pressure by the negative pressure generator 19 and the flow rate becomes excessive without introducing means for controlling the arrival speed, a sudden pressure fluctuation occurs in the meniscus. This is because the meniscus is instantaneously destroyed by this, so that air may be mixed in from the nozzle.

  Therefore, the discharge head device 1 is provided with a negative pressure arrival speed adjustment unit 20 that controls the arrival speed to the specified negative pressure generated by the negative pressure generation unit 19. Will be described in detail.

  In FIG. 4, an ink supply in which a needle valve type speed controller 40 is connected between the tank box 17 and the negative pressure generating unit 19 as a negative pressure reaching speed adjusting unit 20 that controls the speed of reaching a specified negative pressure. An outline of the system is shown. As shown in FIG. 5, the speed controller 40 has a characteristic that the gas flow rate changes linearly according to the number of rotations of the needle, and can adjust the speed of reaching the specified pressure with good controllability. The speed controller 40 has a characteristic that the gas flow rate varies depending on the ultimate pressure even at the same needle rotation speed, and the flow rate at the same rotation speed increases as the ultimate pressure increases. Therefore, the plurality of lines in FIG. 5 indicate the correlation between the needle rotation speed and the gas flow rate at a plurality of ultimate pressures.

  Here, the actual arrival speed control sequence performed under the control of the control unit 25 will be described. The control unit 25 generates a negative pressure in the sub tank 13 from the state in which the sub tank 13 is pressurized by the positive pressure generating unit 18 (for example, cleaning of the nozzle) while the discharge head 11 and the sub tank 13 are in communication. When shifting (returning) to a state where the pressure is reduced by the unit 19, the pressurizing operation of the sub tank 13 by the positive pressure generating unit 18 is stopped, and then the negative pressure generated by the negative pressure generating unit 19 is stopped. The gas flow rate is adjusted by using the speed controller 40, and the speed at which the specified negative pressure applied to the sub tank 13 is reached is suppressed. As a result, it is possible to prevent a sudden negative pressure from being applied to the ejection head 11 and to create a state where ink can be ejected without destroying the meniscus formed on the nozzle surface of the ejection head 11.

  Further, in FIG. 6, the discharge head device 1 in which an electropneumatic regulator 60 is incorporated as a negative pressure arrival speed adjusting unit 20 that controls the arrival speed to the specified negative pressure between the tank box 17 and the negative pressure generating unit 19. An outline of the ink supply system is shown. As shown in FIG. 7, the electropneumatic regulator 60 has a characteristic that the control pressure changes linearly in accordance with the input signal voltage force. Here, a system that can control the input signal in 256 steps is applied, and the set value is divided into multiple steps in advance for the input signal of the electropneumatic regulator 60 required to generate the specified pressure. Prepare multiple setting values.

  The actual reach speed control sequence performed under the control of the control unit 25 will be described. The control unit 25 starts from a state where the sub tank 13 is pressurized by the positive pressure generation unit 18 in a state where the discharge head 11 and the sub tank 13 are in communication (for example, cleaning of the nozzle), and the sub tank 13 is a negative pressure generation unit. When shifting (returning) to the pressure-reduced state at 19, the pressurizing operation of the sub tank 13 by the positive pressure generator 18 is stopped. Next, with respect to the negative pressure generated by the negative pressure generator 19, the set value previously divided is sequentially input from the signal set by the division number 1 using the electropneumatic regulator 60 as shown in FIG. To go. When the signal set by the division number 10 is input, the sub tank 13 is depressurized to a specified pressure. Accordingly, it is possible to create a state in which ink can be ejected without suppressing a sudden negative pressure and destroying the meniscus formed on the nozzle surface of the ejection head 11.

  The same effect can be obtained by using a mass flow controller (not shown) widely used for flow control instead of the speed controller 40 and the electropneumatic regulator 60. A mass flow controller is a control device that integrates a small thermal mass flow meter with a controller and a control valve, and controls the flow rate to a constant value by itself. Here, a thermal mass flowmeter is a device in which a heater is wrapped around a metal thin tube and temperature sensors are placed on both sides of the heater. When no fluid is flowing, the heat of the heater is evenly transmitted to both sides, The output can be balanced, but when the fluid flows, the upstream sensor cools and the output decreases, and the downstream side rises conversely, and the output balance is disrupted. Therefore, the degree of disruption is converted into the fluid flow rate.

  Here, only the pressure switching when the sub tank 13 is shifted from the pressurized state to the negative pressure state has been described, but for example, the power is turned on from the power shut-off state to generate a negative pressure to the sub tank 13. When the normal pressure sub-tank 13 is shifted to the negative pressure state, the above-described abrupt control is performed. The meniscus destruction of the discharge head 11 due to a negative pressure can be avoided.

  In other words, the present invention can also be expressed as follows. That is, the present invention is an ink jet apparatus, and includes a discharge head that discharges ink to a recording medium, a small-capacity subtank that stores a predetermined volume of ink and supplies ink used for printing to the discharge head. In the ink jet recording apparatus having a large capacity main tank for filling the sub tank with ink and a pressure generating mechanism for the discharge head connected to the sub tank and applying at least two different set pressures. At least one of the pressure generating mechanisms is a negative pressure generating means that is connected to the sub tank and generates a specified negative pressure with respect to the discharge head by reducing the pressure of the sub tank. Other than the negative pressure generating means The pressure generating mechanism changes the set negative pressure applied to the discharge head from the specified negative pressure. When, it is characterized in that to control the arrival rate to the prescribed pressure by the adjustment mechanism provided between the negative pressure generating means and the sub-tank.

  In the above configuration, the negative pressure generation means may include a vacuum pump as a negative pressure generation source and a regulator that adjusts the negative pressure generated by the vacuum pump to a specified pressure.

  Alternatively, in the above configuration, the negative pressure generating means includes a negative pressure generator as a negative pressure generation source and a regulator that adjusts the negative pressure generated by the negative pressure generator to a specified pressure. You can also

  Further, in the above configuration, a speed controller is used as the adjusting mechanism provided between the negative pressure generating means and the sub tank, and the speed controller is disposed between the ink tank and the regulator. You can also

  Further, in the above configuration, an electropneumatic regulator is used as the adjustment mechanism provided between the negative pressure generating means and the sub tank, and the electropneumatic regulator is disposed between the ink tank and the regulator. It is also possible to divide the specified negative pressure into a plurality of set pressures and increase the pressure stepwise.

  Further, in the above configuration, a mass flow controller is used as the adjusting mechanism provided between the negative pressure generating means and the sub tank, and the mass flow controller is disposed between the ink tank and the regulator. You can also

  The present invention is also a negative pressure adjusting mechanism for an ink jet recording apparatus, which stores an ejection head that ejects ink onto a recording medium, stores a predetermined volume of ink, and supplies the ejection head with ink used for printing. A small-capacity sub-tank, a large-capacity main tank that fills the sub-tank with ink, and a pressure generation mechanism of the discharge head that is connected to the sub-tank and applies at least two different set pressures, At least one of the plurality of pressure generating mechanisms is a negative pressure generating unit that is connected to the sub tank and generates a specified negative pressure for the discharge head by reducing the pressure of the sub tank. A negative pressure adjusting mechanism of an ink jet recording apparatus capable of controlling the arrival speed when generating the pressure, and generating the pressure other than the negative pressure generating means. When changing from a certain set pressure applied to the discharge head by the mechanism to the specified negative pressure, the speed at which the specified pressure is reached by the adjusting mechanism provided between the negative pressure generating means and the sub tank. It is characterized by controlling.

  The present invention can be applied to an ink jet recording apparatus that performs recording on a recording medium such as paper, a fluid discharge type production apparatus, and the like.

It is a schematic diagram which shows the structure of the discharge head apparatus mounted in the fluid discharge apparatus which concerns on one Embodiment of this invention. It is a schematic diagram which shows one structural example of the negative pressure generation part in the said discharge head apparatus. It is a schematic diagram which shows the other structural example of the negative pressure generation part in the said discharge head apparatus. FIG. 3 is a schematic diagram illustrating a configuration of an ink supply system that uses a speed controller as an adjustment unit that adjusts a negative pressure arrival speed in the ejection head device. It is a figure which shows the flow volume characteristic of the said speed controller. FIG. 3 is a schematic diagram illustrating a configuration of an ink supply system using an electropneumatic regulator as an adjustment unit that adjusts a negative pressure arrival speed in the ejection head device. It is a figure which shows the correlation with the input signal and control pressure of the said electropneumatic regulator. It is a figure explaining the multistage pressure control method by the electropneumatic regulator used for the present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Discharge head apparatus 11 Discharge head 12 Ink (discharge material)
13 Sub tank 14 Main tank 15 Three-way switching valve 18 Positive pressure generating part 19 Negative pressure generating part 19A Negative pressure generating part 19B Negative pressure generating part 20 Negative pressure reaching speed adjusting part 21 Vacuum pump 22 Regulator 30 Vacuum generator 40 Speed controller 60 Electric Empty regulator

Claims (9)

An ejection head for ejecting an ejection material to a medium;
A sub-tank for storing discharge material to be supplied to the discharge head;
A main tank for storing discharge material to be supplied to the sub tank;
A negative pressure generating means connected to the sub tank and depressurizing the sub tank to make the pressure of the discharge head a predetermined negative pressure;
An ejection head device comprising: a negative pressure arrival speed adjusting means for controlling an arrival speed until the negative pressure generating means causes the pressure of the ejection head to reach the predetermined negative pressure.   2. The discharge head device according to claim 1, wherein pressure generating means for connecting the sub tank to a pressure different from that of the negative pressure generating means is connected to the sub tank.   The said negative pressure generation means has a vacuum pump as a negative pressure generation source, and a regulator which adjusts the negative pressure generated by the said vacuum pump to the said defined negative pressure. Discharge head device.   The negative pressure generating means includes a negative pressure generator as a negative pressure generation source, and a regulator for adjusting the negative pressure generated by the negative pressure generator to the predetermined negative pressure. 2. The ejection head device according to 1.   2. The discharge head device according to claim 1, wherein the negative pressure arrival speed adjusting means comprises a speed controller and is disposed between the sub tank and the negative pressure generating means.   The negative pressure arrival speed adjusting means is composed of an electropneumatic regulator, and is arranged between the sub tank and the negative pressure generating means, and divides the determined negative pressure into a plurality of set pressures, and gradually sets the set pressures. The ejection head device according to claim 1, wherein the speed of reaching the predetermined negative pressure is adjusted by increasing the discharge head device.   2. The discharge head device according to claim 1, wherein the negative pressure arrival speed adjusting means comprises a mass flow controller and is disposed between the sub tank and the negative pressure generating means.   A fluid ejection device comprising the ejection head device according to claim 1. In the fluid ejection method for controlling the pressure of the ejection head that ejects the ejection material to the medium to a negative pressure determined by depressurizing the tank that supplies the ejection material to the ejection head by the negative pressure generating means,
A fluid ejection method for controlling an arrival speed when the pressure of the ejection head is reached from the pressure different from the predetermined negative pressure to the predetermined negative pressure.

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