JP6077188B2 - Liquid supply device and liquid discharge device - Google Patents

Description

  The present invention relates to a liquid supply apparatus and a liquid discharge apparatus, and more particularly to a pressure control technique for supplying liquid to a liquid discharge head.

  In recent years, there has been an increasing demand for small copy printing in the printing industry. Since it is necessary to create a plate in offset printing, time and cost have become obstacles in printing a small number of copies. One method for solving this problem is to use single-pass inkjet recording.

  In an inkjet recording apparatus, in order to stably supply ink to the inkjet head and operate the inkjet head stably, it is necessary to control the internal pressure of the ink flow path for supplying ink and the internal pressure of the inkjet head to be constant. There is. For this pressure control, a damper configured to include a liquid chamber communicating with the ink flow path, and a gas chamber arranged to face the liquid chamber and the elastic film is disposed in the ink flow path. There are known techniques for suppressing fluctuations in internal pressure and fluctuations in internal pressure of an inkjet head.

  Japanese Patent Application Laid-Open No. 2004-228561 describes a technique in which a damper volume is set to be large when non-ejection and a damper volume is set to small during ejection in a damper provided in an ink flow path. According to this technique, pulsation due to the supply pump can be suppressed during non-discharge, and pressure fluctuation due to discharge can be effectively suppressed during discharge.

JP 2013-71247 A

  In single-pass high-speed printing, the amount of ink consumed is large and the pressure fluctuation increases, so that it is necessary to enlarge the damper provided in the liquid flow path. On the other hand, when the damper is increased in size, the expansion and contraction of the gas chamber with respect to the temperature change is increased, so that the damper performance is sensitive to the temperature change. This is not limited to a single-pass inkjet recording apparatus, but is a general problem with liquid supply apparatuses. However, the invention described in Patent Document 1 does not consider temperature change.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid supply device and a liquid discharge device that eliminate the influence of temperature change and perform stable pressure control.

  In order to achieve the above object, one aspect of the liquid supply apparatus includes a liquid flow path that connects a liquid discharge head that discharges liquid from a nozzle and a liquid tank that stores liquid, and the liquid flow path. A pump for applying pressure to the liquid in the channel, and a pressure adjusting means provided between the liquid discharge head and the pump, wherein the liquid chamber communicating with the liquid channel via the flow port is sealed with the gas. Pressure adjusting means having a gas chamber of variable volume, an elastic membrane separating the liquid chamber and the gas chamber, a sensor for measuring the state of the gas chamber and outputting a measurement value, and a gas according to the measurement value Volume changing means for keeping the pressure inside the gas chamber constant by changing the volume of the chamber. Here, “measurement of the situation” means measurement of a physical quantity capable of keeping the pressure inside the gas chamber constant by changing the volume of the gas chamber based on the measured value. For example, it means the measurement of temperature and pressure.

  According to this aspect, since the pressure inside the gas chamber is kept constant by changing the volume of the gas chamber according to the measured value of the sensor, the influence of the temperature change is eliminated, and stable pressure control is performed. It can be carried out. Note that keeping the pressure constant does not mean that the pressure is strictly fixed to the same value, but means that the pressure falls within a range that is allowed under normal use environment conditions. The value within the allowable range refers to a pressure value within a range in which no problem in use occurs in the liquid discharge head supplied with the liquid as a result of pressure adjustment by the pressure adjusting means.

  The liquid supply device includes a storage unit that stores an initial value of the measurement value, a change amount calculation unit that calculates a measurement value change amount from the newly measured measurement value, and a gas chamber from the calculated measurement value change amount. It is preferable to include a volume change amount calculation means for calculating a change amount of the volume of the gas chamber so that the internal pressure of the gas chamber becomes the pressure at the time of measurement of the initial value. As a result, the volume changing means can change the volume of the gas chamber to return the pressure inside the gas chamber to the pressure at the time of measurement of the initial value, so that the pressure inside the gas chamber can be kept constant. it can.

  It is preferable that the gas chamber has an expansion / contraction part that can change the volume of the gas chamber by expanding and contracting, and the volume changing unit continuously changes the volume of the gas chamber by controlling expansion / contraction of the expansion / contraction part. Thereby, the pressure inside the gas chamber can be kept more constant.

  The volume changing means preferably includes a linear stepping motor that expands and contracts the expansion / contraction part of the gas chamber. Thereby, the volume of a gas chamber can be changed appropriately.

  The liquid supply apparatus includes drive amount calculation means for calculating the drive direction and drive amount of the linear stepping motor from the calculated change amount of the gas chamber volume, and the volume change means is linear by the calculated drive amount in the calculated drive direction. It is preferable to drive the stepping motor. Thereby, a linear stepping motor can be driven appropriately.

  It is preferable that the change amount of the volume and the drive amount of the linear stepping motor have a linear relationship. Thereby, the volume of the gas chamber can be accurately changed.

  The stretchable part preferably has a bellows part. The stretchable part may have a cylinder part. Thereby, an expansion-contraction part can be comprised with a simple structure.

  The sensor may be a temperature sensor that outputs the temperature of the gas chamber as a measurement value, or may be a pressure sensor that outputs the pressure of the gas chamber as a measurement value. Thereby, the pressure fluctuation of a gas chamber can be known appropriately.

  The gas chamber preferably includes a first gas chamber having a constant volume and separated from the liquid chamber by an elastic film, and a second gas chamber having a variable volume communicating with the first gas chamber. Moreover, it is preferable that the liquid chamber and the first gas chamber are integrally formed, and the first gas chamber and the second gas chamber are communicated with each other through a communication path. By configuring the gas chamber in this manner, more appropriate pressure control is possible.

  In order to achieve the above object, one aspect of a liquid discharge apparatus includes a liquid tank that stores liquid, a liquid discharge head that discharges liquid from a nozzle, a liquid discharge head that discharges liquid from a nozzle, and a liquid that stores liquid A liquid flow path communicating with the tank, a pump provided in the liquid flow path for applying pressure to the liquid in the liquid flow path, and a pressure adjusting means provided between the liquid discharge head and the pump. Pressure adjusting means having a liquid chamber communicating with the liquid flow path through the mouth, a variable volume gas chamber in which gas is sealed, and an elastic membrane separating the liquid chamber and the gas chamber; Supply using a liquid supply device comprising a sensor for measuring the pressure and outputting a measurement value, and a volume changing means for keeping the pressure inside the gas chamber constant by changing the volume of the gas chamber according to the measurement value Means, a liquid tank and a liquid A supply unit that is disposed between the liquid discharge head and supplies the liquid stored in the liquid tank to the liquid discharge head; a moving unit that relatively moves the liquid discharge head and the medium; The discharge control means for discharging the liquid from the nozzle of the liquid discharge head and applying the liquid to the medium.

  According to this aspect, since the pressure inside the gas chamber is kept constant by changing the volume of the gas chamber according to the measured value of the sensor, the influence of the temperature change is eliminated, and stable pressure control is performed. The liquid can be discharged stably from the liquid discharge head.

  A liquid ejection device includes a liquid channel that communicates a liquid ejection head that ejects liquid from a nozzle and a liquid tank that stores liquid, a pump that is provided in the liquid channel, and that applies pressure to the liquid in the liquid channel; A pressure adjusting means provided between the liquid discharge head and the pump, the liquid chamber communicating with the liquid flow path through the flow port, the variable volume gas chamber sealed with gas, the liquid chamber and the gas An elastic membrane for isolating the chamber, a sensor for measuring the state of the gas chamber and outputting a measured value, and changing the volume of the gas chamber according to the measured value to thereby change the inside of the gas chamber. A recovery means using a liquid supply device having a volume changing means for keeping the pressure of the liquid constant, and is disposed between the liquid discharge head and the liquid tank, and the liquid supplied to the liquid discharge head is supplied to the liquid tank. You may provide the collection means to collectEven in the liquid flow path for recovering the liquid from the liquid discharge head to the liquid tank, the influence of temperature change can be eliminated and stable pressure control can be performed, so that stable liquid discharge from the liquid discharge head can be performed. .

  According to the present invention, the influence of temperature change can be eliminated and stable pressure control can be performed.

FIG. 1 is a schematic diagram illustrating the overall configuration of the ink supply device 10. FIG. 2 is a block diagram illustrating a system configuration of the ink supply apparatus 10. FIG. 3 is a flowchart showing the pressure control operation of the ink supply device 10. FIG. 4 is a graph showing changes in the temperature, internal pressure, and volume of the air chamber 34. FIG. 5 is a schematic diagram showing the overall configuration of the ink supply device 60. FIG. 6 is a schematic diagram illustrating the overall configuration of the ink supply device 70. FIG. 7 is a block diagram showing a system configuration of the ink supply device 70. FIG. 8 is a flowchart showing the pressure control operation of the ink supply device 70. FIG. 9 is a diagram showing a mode in which the adjustment air chamber 36 is driven by bimetal. FIG. 10 is a schematic diagram illustrating the overall configuration of the ink supply apparatus 100. FIG. 11 is a block diagram illustrating a system configuration of the ink supply apparatus 100. FIG. 12 is a schematic diagram showing the overall configuration of the inkjet recording apparatus 200. FIG. 13 is a block diagram illustrating a system configuration of the inkjet recording apparatus 200.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
[Overall configuration of ink supply device]
The ink supply device 10 (an example of a liquid supply device) according to the first embodiment includes an ink jet head 50 (an example of a liquid ejection head) to which ink (an example of a liquid) stored in an ink tank 52 is supplied. This is a non-circulating liquid supply device that controls the internal pressure (negative pressure) of the inkjet head 50 by the amount of ink fed.

  As shown in FIG. 1, the ink supply device 10 includes a supply flow path 12, supply valves 14-1, 14-2,..., And 14-n, dampers 15-1, 15-2,. The sensor 16, the supply sub tank 18, the supply pump 20, and the like are included.

  The supply channel 12 (an example of a liquid channel) communicates the ink tank 52 and the inkjet head 50 via the supply pump 20, the supply sub tank 18, the manifold 54, and the like.

  The inkjet head 50 is configured by connecting n head modules 51-1, 51-2,..., 51-n each provided with a plurality of nozzles (not shown) for ejecting ink. .

  Each of the head modules 51-1, 51-2,..., 51-n has an ink supply port 51A to which ink is supplied. Each of the ink supply ports 51A of the head modules 51-1, 51-2,..., 51-n includes supply valves 14-1, 14-2,. ... and 15-n communicate with the supply flow path 12.

  The supply valves 14-1, 14-2,..., And 14-n are channel opening / closing means for switching communication / blocking between the manifold 54 and the dampers 15-1, 15-2,. The supply valves 14-1, 14-2,..., And 14-n are connected to the nozzles of the head modules 51-1, 51-2,. A normally closed or latch type electromagnetic valve whose opening / closing is controlled by a control signal is applied so that ink does not leak out.

  The dampers 15-1, 15-2,..., And 15 -n are the nozzle discharge operations and supply valves 14-1, 14-2,. 14 is a pressure adjusting unit for suppressing pulsation of ink generated by opening and closing of 14-n.

  The pressure sensor 16 is a pressure measuring unit that measures the internal pressure of the supply flow path 12, and is disposed between the supply sub tank 18 and the manifold 54. As the pressure sensor 16, a sensor such as a semiconductor piezoresistive method, a capacitance method, or a silicon resonant method can be applied.

  The supply sub-tank 18 is a pressure adjustment unit that performs pressure adjustment so as to suppress fluctuations in the internal pressure of the supply flow path 12. The supply sub-tank 18 partitions (isolates) the inside of the sealed container using an elastic membrane 22, one side of the elastic membrane 22 is a liquid chamber 24 (an example of a liquid chamber), and the other side is a main air chamber 26 (elastic membrane). (An example of a first gas chamber having a constant volume and separated from the liquid chamber) (an example in which the liquid chamber and the first gas chamber are integrally formed). The elastic film 22 is made of a flexible material that can be easily deformed.

  The supply pump 20 is a liquid pressure applying unit that applies pressure to the ink inside the supply flow path 12. For example, a tube pump can be applied to the supply pump 20.

  The ink tank 52 (an example of a liquid tank) is a storage unit that stores ink to be supplied to the inkjet head 50. The ink stored in the ink tank 52 is supplied by the supply pump 20 to the supply sub tank 18, the manifold 54, the supply valves 14-1, 14-2,..., And 14-n, and the dampers 15-1, 15-2,. , And 51-n of the inkjet head 50 via 15-n.

  In the liquid chamber 24 of the supply sub tank 18, an ink outlet 24A (an example of a circulation port) and an ink inlet 24B (an example of a circulation port) are provided. The ink outlet 24 </ b> A communicates with the manifold 54 via the supply channel 12, and the ink inlet 24 </ b> B communicates with the supply pump 20 via the supply channel 12.

  When ink flows into the liquid chamber 24 from the ink inlet 24B, the elastic film 22 is deformed toward the main air chamber 26 according to the volume of the ink that flows in. As a result, the volume of the ink flowing out from the ink outlet 24A does not change, and the flow rate of the ink flowing out from the liquid chamber 24 is constant. Therefore, the supply subtank 18 can suppress fluctuations in the internal pressure of the inkjet head 50 due to the discharge operation from the nozzles and fluctuations in the internal pressure of the supply flow path 12 due to the pulsating flow due to the liquid feeding operation of the supply pump 20. it can.

  In addition, the ink supply device 10 includes an air flow path 32, an adjustment air chamber 36, a thermistor 42, a linear stepping motor 44, and the like as a gas elasticity adjustment unit for determining the pressure adjustment performance of the supply sub tank 18.

  The main air chamber 26 of the supply subtank 18 (an example of a first gas chamber having a constant volume) is provided with an air flow passage opening 26A, and a regulated air chamber 36 (a variable volume second air communicating with the first gas chamber). An example of the gas chamber) is provided with an air flow passage opening 36A. Further, the air channel communication port 26A and the air channel communication port 36A communicate with the air channel 32. That is, the main air chamber 26 and the adjustment air chamber 36 communicate with each other via the air flow path 32 and form a space in which gas is sealed (the first gas chamber and the second gas chamber). An example of communication with the communication path). A sealed space including the main air chamber 26, the air flow path 32, and the adjustment air chamber 36 is referred to as an air chamber 34 (an example of a variable volume gas chamber in which gas is sealed).

  The adjustment air chamber 36 has a bellows portion 37 that can expand and contract on the side wall. The adjustment air chamber 36 is configured so that the internal volume of the adjustment air chamber 36 can be continuously changed by continuously changing from the folded state of the bellows portion 37 (an example of the expansion / contraction portion) to the extended state. Has been.

  The thermistor 42 (an example of a temperature sensor) is a temperature measurement unit that measures the temperature of the air chamber 34 (an example of the state of the gas chamber) and outputs a measurement value. Here, the thermistor 42 is in direct contact with the main air chamber 26 and measures the temperature of the air chamber 34. However, the thermistor 42 measures the atmosphere temperature of the ink supply device 10, the main air chamber 26, and the adjustment air chamber 36. A mode in which the temperature of the gas inside the air chamber 34 is measured is also possible.

  The linear stepping motor 44 (an example of a volume changing unit) includes a shaft 45 configured to reciprocate in a direction parallel to the side wall of the adjustment air chamber 36, and the shaft 45 is fixed to the upper wall 38 of the adjustment air chamber 36. ing. The lower wall 39 of the adjustment air chamber 36 is supported and fixed at a fixed position. Therefore, when the linear stepping motor 44 is driven to reciprocate the shaft 45, the upper wall 38 reciprocates while the lower wall 39 of the adjustment air chamber 36 is fixed, and the bellows portion 37 on the side wall expands and contracts. Thereby, the volume inside the adjustment air chamber 36 increases / decreases, and as a result, the volume inside the air chamber 34 increases / decreases.

  Note that the configuration for reciprocating the upper wall 38 is not limited to a mode using a linear stepping motor, and a mode using a rack and pinion mechanism or a feed screw mechanism is also possible.

[System configuration of ink supply device]
As shown in FIG. 2, the ink supply device 10 controls the supply valves 14-1, 14-2,..., 14-n, the pressure sensor 16, the supply pump 20, the thermistor 42, and the linear stepping motor 44 described above. Unit 46, memory 48, timer 49, and the like.

  The control unit 46 is a control unit that performs overall control of the ink supply device 10. The control unit 46 controls the supply valves 14-1, 14-2,..., And 14 -n, and switches whether ink is supplied to the inkjet head 50. In addition, the control unit 46 can acquire the operation status of the inkjet head 50 from the inkjet head 50. Further, the control unit 46 controls the supply pump 20 based on the measurement result of the pressure sensor 16 and controls the internal pressure of the supply flow path 12. Further, although details will be described later, the linear stepping motor 44 is controlled based on the measurement result of the thermistor 42.

  The memory 48 is a storage unit that stores various parameters used by the control unit 46. The timer 49 is a time measuring unit that measures time according to the control of the control unit 46.

[Ink supply pressure control]
The ink supply pressure control of the ink supply apparatus 10 will be described with reference to the flowchart shown in FIG.

  First, the elastic film 22 is initialized (step S1). When the control unit 46 initializes the elastic film 22, the supply valves 14-1, 14-2,..., And so that ink is not discharged from the nozzles of the head modules 51-1, 51-2,. 14-n is blocked. Further, the control unit 46 controls the linear stepping motor 44 to set the shaft 45 to the initial position, and sets the expansion / contraction amount of the bellows portion 37 to a predetermined initial expansion / contraction amount. Thereby, the volume of the air chamber 34 is set to a predetermined initial volume.

  Subsequently, the control unit 46 opens an air communication port (not shown) provided in the main air chamber 26 or the adjustment air chamber 36 to make the inside of the air chamber 34 communicate with the atmosphere. Thereby, the inside of the air chamber 34 becomes atmospheric pressure. In addition, the control unit 46 controls the supply pump 20 based on the measurement result of the pressure sensor 16 to make the inside of the liquid chamber 24 atmospheric pressure. That is, the pressure in the liquid chamber 24 and the pressure in the main air chamber 26 are balanced. In this equilibrium state, the open air communication port is closed to block the inside of the air chamber 34 from the atmosphere, and the air chamber 34 is sealed. Thereby, the volume of the air chamber 34 is set.

  Next, the control unit 46 controls the supply pump 20 based on the measurement result of the pressure sensor 16 to adjust the internal pressure of the liquid chamber 24 to a negative pressure having a predetermined value. Thereby, the initialization of the elastic film 22 is completed.

  After the elastic membrane 22 is initialized, the control unit 46 opens the supply valves 14-1, 14-2,..., And 14-n, and controls the supply pump 20, whereby the head modules 51-1, 51-2, ... and 51-n can be supplied with ink. In the present embodiment, the inkjet head 50 operates according to a print job, and the control unit 46 can acquire the operating status of the inkjet head 50. Accordingly, the control unit 46 starts supplying ink to the inkjet head 50 with the start of operation of the inkjet head 50.

Next, the control unit 46 initializes the elapsed time t to an initial time _{t 0} (step S2). The initial time t ₀ is stored in the memory 48 in advance, and for example, the initial time t ₀ = 0 [minutes] can be set. Further, the control unit 46 acquires the temperature of the air chamber 34 from the thermistor 42, and uses the acquired temperature as the initial temperature T ₀ [K] (an example of the initial value of the measured value) when the volume of the air chamber 34 is set. Store in the memory 48 (step S3).

Control unit 46 increments the elapsed time t by using the timer 49 (step S4), and increments a result, determines whether the elapsed time t becomes the temperature measurement time t ₁ which is determined in advance (step S5) . The temperature measurement time t ₁ is stored in advance in the memory 48, and even if the pressure of the air chamber 34 fluctuates due to a rapid temperature change, this fluctuation in pressure does not cause a problem in use in the inkjet head 50. The time is set to fall within the range. For example, the temperature measurement time t ₁ can be set to 10 [minutes].

When the elapsed time t reaches the temperature measurement time t ₁ (Yes in step S5), the control unit 46 acquires the temperature of the air chamber 34 from the thermistor 42, and stores the acquired temperature as the current temperature T ₁ [K] in the memory 48. (Step S6). Then, whether or not the current temperature T ₁ and the initial temperature T ₀ stored in the memory 48 are the same temperature, that is, whether or not the temperature of the air chamber 34 has changed since the volume of the air chamber 34 was set. Is determined (step S7). The present temperature T ₁ and the initial temperature T ₀ are not limited to the same temperature, and the case where the difference between the current temperature T ₁ and the initial temperature T ₀ is within a certain range may be regarded as the same temperature.

When the current temperature T ₁ and the initial temperature T ₀ are the same temperature, that is, when the temperature of the air chamber 34 has not changed since the volume of the air chamber 34 was set (Yes determination in step S7), the elapsed time t is set. initialized to an initial time _{t 0} (step S8).

On the other hand, when the current temperature T ₁ is different from the initial temperature T _0, that is, when the temperature of the air chamber 34 has changed since the volume of the air chamber 34 was set (No determination in step S7), this temperature Due to the change, the internal pressure of the air chamber 34 may change, and the pressure adjustment of the supply flow path 12 may not be performed properly. Therefore, by changing the volume of the adjustment air chamber 36, the internal pressure of the air chamber 34 is returned to the internal pressure at the time of setting the volume, and the internal pressure of the air chamber 34 is controlled to be constant.

In this case, first, the control unit 46 (an example of the change amount calculating means and the volume change amount calculating means) uses the gas state equation to set the internal pressure of the air chamber 34 to the internal pressure when the volume of the air chamber 34 is set. The amount of change ΔV of the volume of the air chamber 34 for returning to (atmospheric pressure) (an example of the amount of change of the volume of the gas chamber for setting the pressure inside the gas chamber to the pressure at the time of measurement of the initial value) is calculated ( Step S9). This volume change amount ΔV is:
ΔV = nR (T ₁ −T ₀ ) / P (Formula 1)
Can be calculated. Here, n is the number of moles [mol] of the gas inside the air chamber 34, R is the gas constant [Pa · m ³ / (mol · K)] of the gas inside the air chamber 34, and T ₁ is at step S6. The acquired current temperature [K] of the air chamber 34, T ₀ is the initial temperature [K] of the air chamber 34 acquired in step S3, P is the internal pressure [Pa] when the volume of the air chamber 34 is set, Here it is atmospheric pressure. T ₁ -T ₀ corresponds to the measured value change amount.

Next, the control unit 46 (an example of the drive amount calculation means) calculates the expansion amount or the reduction amount of the bellows portion 37 of the adjustment air chamber 36 corresponding to the volume change amount ΔV of the air chamber 34 calculated in step S9. The calculated extension amount or reduction amount of the bellows portion 37 is converted into the drive direction and drive amount of the linear stepping motor 44 (step S10). As shown in Equation 1, the initial case temperature T ₀ than with the higher current temperature T ₁ of the ΔV is a positive value, a negative value ΔV is if it is low the current temperature T ₁ of the initial temperature T ₀ Become. Therefore, the moving direction of the shaft 45 of the linear stepping motor 44 is a direction in which the bellows portion 37 is extended when ΔV is a positive value, and a direction in which the bellows portion 37 is reduced when ΔV is a negative value. Further, the change rate of ΔV with respect to the movement amount of the shaft 45 is linear (an example of a linear relationship).

  The control unit 46 drives the linear stepping motor 44 based on the drive direction and drive amount of the linear stepping motor 44 converted in step S10, and expands or contracts the bellows portion 37 of the adjustment air chamber 36, so that the volume of the air chamber 34 is increased. Is changed by ΔV (step S11). As a result, the volume of the air chamber 34 is reset, and the internal pressure of the air chamber 34 is maintained at the internal pressure (atmospheric pressure) at the time of volume setting, that is, the pressure before the temperature change. Therefore, the pressure adjustment of the supply flow path 12 can be performed appropriately.

Further, the control unit 46 updates the initial temperature _{T 0} to the current temperature _{T 1} (step S12). That is, the temperature stored in the memory 48 as a new initial temperature T ₀ when performing resetting of the volume of the air chamber 34. Thereafter, the control unit 46 initializes the elapsed time t to an initial time _{t 0} (step S8).

  Finally, the control unit 46 determines whether or not the print job is completed, that is, whether or not the ink jet head 50 is in operation and supply of ink by the supply pump 20 and adjustment of the internal pressure of the supply flow path 12 are necessary. Is determined (step S13). This determination is performed when the control unit 46 acquires the operation status from the inkjet head 50.

  When the print job is completed, it is not necessary to supply ink to the head modules 51-1, 51-2,..., 51-n and to adjust the internal pressure of the supply flow path 12, so the supply pump 20 is stopped, The supply valves 14-1, 14-2,..., And 14-n are closed, and the process ends.

  If the print job is not completed and the inkjet head 50 is operating, the process returns to step S4 and the same processing is repeated.

  By controlling the volume of the air chamber 34 as described above, the internal pressure of the air chamber 34 can always be kept constant while the inkjet head 50 is operating. Therefore, even when the temperature change of the air chamber 34 (change in the ambient temperature of the ink supply device 10) occurs, the damper performance of the supply sub tank 18 can be kept constant, and the internal pressure of the supply flow path 12 can be maintained. The fluctuation can be stably suppressed.

  Here, the temperature, internal pressure, and volume of the air chamber 34 will be described with reference to FIGS. 3 and 4. 4A is a graph showing the temperature of the air chamber 34, FIG. 4B is a graph showing the internal pressure of the air chamber 34, and FIG. 4C is a graph showing the volume of the air chamber 34, each represented by the same time axis. ing.

As shown in FIG. 4, the air chamber 34 has a temperature T ₁₀ , a pressure P ₁₀ , and a volume V ₁₀ at time t ₁₀ . It initializes the elastic membrane 22 in the time t _10, and that sets the volume of the air chamber 34. At this time, the control unit 46 stores the temperature T ₁₀ acquired from the thermistor 42 in the memory 48 as the initial temperature T ₀ .

Thereafter, the temperature of the air chamber 34 changes to T ₁₁ (T ₁₁ > T ₁₀ ) and the pressure changes to P ₁₁ (P ₁₁ > P ₁₀ ) at time t ₁₁ . In this time t _11, and that now the temperature measurement time t ₁ in step S5 of the flowchart shown in FIG.

At time _{t 11,} if it is Yes in determination of Step S5, the control unit 46 acquires the temperature of the air chamber 34 from the thermistor 42, stored in the memory 48 the temperature _{T 11} was obtained as the current temperature _T 1 [K] To do. Since the initial temperature T ₀ stored in the memory 48 is T ₁₀ and T ₁ ≠ T ₀ , No determination is made in step S7, and the process proceeds to step S9.

In step S9, the change amount ΔV of the volume of the air chamber 34 is calculated using Equation 1. Here, it is assumed that the calculated change amount ΔV of the volume of the air chamber 34 satisfies the relationship ΔV = V ₁₁ −V ₁₀ .

  The process proceeds to step S10, and the drive direction and drive amount of the linear stepping motor 44 are converted from the change amount ΔV of the volume of the air chamber 34. Here, the temperature of the air chamber 34 rises, and the internal pressure of the air chamber 34 rises. Therefore, the driving direction of the linear stepping motor 44 is determined as the extending direction of the bellows portion 37. Further, the extension amount corresponding to the change amount ΔV of the volume of the air chamber 34 is calculated.

The process proceeds to step S11, and the linear stepping motor 44 is driven by this extension amount. As shown in FIG. 4 (c), by driving the control unit 46 is a linear stepping motor 44 during the time _{t 11} to time _{t 12,} the volume of the air chamber 34 increases from _{V 10} to _{V 11.} Further, as shown in FIG. 4 (b), with the change in volume of the air chamber 34, the internal pressure of the air chamber 34 is changed from _{P 11} to _{P 10.} That is, the internal pressure of the air chamber 34 is returned to the internal pressure P ₁₀ when the volume of the air chamber 34 is set.

  Here, the case where the volume of the air chamber 34 is increased as the temperature of the air chamber 34 increases is described. However, when the temperature of the air chamber 34 decreases, the volume of the air chamber 34 is similarly set. You can decrease it.

Thus, even when the temperature of the air chamber 34 is changed, it is possible to adjust the internal pressure of the air chamber 34 to the pressure P ₁₀ at the time of volume setting.

<Second Embodiment>
The adjustment air chamber 36 may be configured such that the internal volume can be changed continuously using a cylinder structure. FIG. 5 is a schematic diagram illustrating an overall configuration of an ink supply device 60 according to the second embodiment. Portions common to the ink supply device 10 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 5, the adjustment air chamber 36 of the ink supply device 60 includes a cylinder part 62 and a piston part 64 (an example of an expansion / contraction part) that can slide inside the cylinder part 62.

  The linear stepping motor 44 includes a shaft 45 configured to reciprocate in a direction parallel to the sliding direction of the piston portion 64, and the shaft 45 is fixed to the piston portion 64. The cylinder part 62 of the adjustment air chamber 36 is supported and fixed at a fixed position. Therefore, when the linear stepping motor 44 is driven to reciprocate the shaft 45, the piston portion 64 reciprocates while the cylinder portion 62 is fixed, and the adjustment air chamber formed from the cylinder portion 62 and the inner wall of the piston portion 64. The internal volume of 36 increases or decreases. As a result, the volume inside the air chamber 34 continuously increases and decreases. The change rate of ΔV with respect to the movement amount of the shaft 45 is linear (an example of a linear relationship).

  Thus, even when the adjustment air chamber 36 is configured using a cylinder structure, the volume inside the air chamber 34 can be continuously changed, and ink supply similar to the flowchart shown in FIG. Pressure control can be performed.

<Third Embodiment>
[Overall configuration and system configuration of ink supply device]
In the ink supply device 10 and the ink supply device 60, the temperature of the air chamber 34 is measured as a parameter relating to pressure adjustment (the state of the gas chamber), and the linear stepping motor 44 is controlled according to the change in temperature. The internal pressure may be measured by a pressure sensor. FIG. 6 is a schematic diagram showing the overall configuration of the ink supply device 70 according to the third embodiment, and FIG. 7 is a block diagram showing the system configuration of the ink supply device 70. In addition, the same code | symbol is attached | subjected to the part which is common in FIG.1 and FIG.2, and the detailed description is abbreviate | omitted.

  The ink supply device 70 includes a pressure sensor 43 for measuring the internal pressure of the air chamber 34 (an example of the state of the gas chamber) in the main air chamber 26. The pressure sensor 43 may be disposed in the adjustment air chamber 36. The pressure sensor 43 measures the internal pressure of the air chamber 34 and outputs the measured value to the control unit 46.

[Ink supply pressure control]
The ink supply pressure control of the ink supply device 70 will be described with reference to the flowchart shown in FIG. In addition, the same code | symbol is attached | subjected to the part which is common in FIG. 3, and the detailed description is abbreviate | omitted.

First it initializes the elastic membrane 122 (step S1), and then initializes the elapsed time t to an initial time _{t 0} (step S2).

In addition, the control unit 46 acquires the internal pressure of the air chamber 34 from the pressure sensor 43 and sets the acquired pressure to the initial pressure P ₀ [Pa] (an example of the initial value of the measured value). ) In the memory 48 (step S21).

Thereafter, it timed with a timer 49 (step S4), and the elapsed time t becomes a pressure measuring time _{t 1} (Yes judgment in step S5), and the control unit 46 obtains the internal pressure of the air chamber 34 from the pressure sensor 43 Then, the acquired internal pressure is stored in the memory 48 as the current pressure P ₁ [Pa] (step S22).

Then, whether or not the present pressure P ₁ and the initial pressure P ₀ stored in the memory 48 are the same pressure, that is, whether the internal pressure of the air chamber 34 has changed since the volume of the air chamber 34 was set. It is determined whether or not (step S23). Note that the present pressure P ₁ and the initial pressure P ₀ are not limited to the same pressure, and the case where the difference between the current pressure P ₁ and the initial pressure P ₀ is within a certain range may be regarded as the same pressure.

If the current pressure P ₁ and the initial pressure P ₀ are the same pressure, that is, if the internal pressure of the air chamber 34 has not changed since the volume of the air chamber 34 was set (Yes determination in step S23), the elapsed time the t is initialized to an initial time _{t 0} (step S8).

On the other hand, when the current pressure P ₁ is different from the initial pressure P ₀ , that is, when the internal pressure of the air chamber 34 has changed since the volume of the air chamber 34 was set (No determination in step S23), Due to this pressure change, there is a possibility that the pressure adjustment of the supply flow path 12 is not properly performed. Therefore, by changing the volume of the adjustment air chamber 36, returning the internal pressure of the air chamber 34 to the initial pressure P _0, performs control to keep constant.

In this case, the control unit 46 first acquires the temperature T of the air chamber 34 from the thermistor 42 (step S24). Next, the control unit 46 (an example of the change amount calculation unit and the volume change amount calculation unit) uses the gas state equation to set the internal pressure of the air chamber 34 to be constant (atmospheric pressure). A volume change amount ΔV (an example of a gas chamber volume change amount for keeping the pressure inside the gas chamber constant) is calculated (step S25). This volume change amount ΔV is:
ΔV = nRT / (P ₁ −P ₀ ) (Expression 2)
Can be calculated. Here, n is the number of moles [mol] of the gas inside the air chamber 34, R is the gas constant [Pa · m ³ / (mol · K)] of the gas inside the air chamber 34, and T is obtained in step S24. temperatures of the air chamber 34 [K], _{P 1} is the current pressure in the air chamber 34 obtained in step S22 [Pa], _{P 0} is the initial pressure in the air chamber 34 obtained in step S21 [Pa]. P ₁ -P ₀ corresponds to the measured value change amount.

  The expansion amount or the reduction amount of the bellows portion 37 of the adjustment air chamber 36 corresponding to the volume change amount ΔV of the air chamber 34 is calculated, and the calculated extension amount or reduction amount of the bellows portion 37 is calculated as the driving direction of the linear stepping motor 44. And it converts into drive amount (step S10).

Further, the linear stepping motor 44 is driven based on the driving direction and driving amount of the linear stepping motor 44, the bellows portion 37 of the adjustment air chamber 36 is expanded or contracted, the volume of the air chamber 34 is changed by ΔV, and the air chamber The internal pressure of 34 is maintained at the pressure before the temperature change (initial pressure P ₀ ).

Then, it initializes the elapsed time t to an initial time t ₀ (step S8), and repeats the same processing until the print job ends.

  By controlling the volume of the air chamber 34 in this way, the internal pressure of the air chamber 34 can always be kept constant while the inkjet head 50 is operating. Therefore, even if the internal pressure changes due to the temperature change of the air chamber 34 (change in the ambient temperature of the ink supply device 10), the damper performance of the supply sub tank 18 can be kept constant, and the supply flow path 12 internal pressure fluctuations can be stably suppressed.

  Note that the linear stepping motor 44 may be operated by feedback control based on the measurement value of the pressure sensor 43. In this case, the thermistor 42 is not necessary.

<Other modes of pressure control>
The adjustment air chamber 36 is not limited to a mode in which the linear stepping motor 44 is driven in accordance with the measurement results of the thermistor 42 and the pressure sensor 43, and may be directly driven by a thermal deformation body.

  As shown in FIG. 9A, the adjustment air chamber 36 according to this aspect includes a bellows portion 37 that can expand and contract on the side wall, and a bimetal 80 is fixed to the upper wall 38 as a heat deformable body. . The lower wall 39 is supported and fixed at a fixed position.

  The bimetal 80 (an example of a volume changing unit) includes a first metal plate 82 having a first coefficient of thermal expansion and a second coefficient having a second coefficient of thermal expansion that is relatively smaller than the first coefficient of thermal expansion. The metal plate 84 is joined to each other to form a plate shape. The bimetal 80 is fixedly supported at one end so that the first metal plate 82 is located on the side relatively close to the upper wall 38 and the second metal plate 84 is located on the side relatively far from the upper wall 38. The first metal plate 82 and the upper wall 38 are fixed at a position on the other end side.

  In the bimetal 80 configured as described above, when the ambient temperature rises, the first metal plate 82 expands relatively larger than the second metal plate 84, and the first metal plate 82 and the upper wall 38 are fixed. The position is deformed in a direction away from the lower wall 39. Thereby, the bellows part 37 of a side wall expand | extends and the volume inside the adjustment air chamber 36 increases (FIG.9 (b)). As a result, the internal volume of the air chamber 34 (not shown in FIG. 9) increases. Here, the first thermal expansion coefficient and the second thermal expansion coefficient are set so that the internal pressure of the air chamber 34 becomes constant with respect to the change in temperature.

  Further, when the ambient temperature is lowered from this state, the amount of expansion of the first metal plate 82 which has expanded relatively larger than that of the second metal plate 84 decreases, and the fixing position of the first metal plate 82 and the upper wall 38 is reduced. Is deformed in a direction approaching from the lower wall 39. Thereby, the bellows part 37 of a side wall shrinks and the volume inside the adjustment air chamber 36 reduces (FIG. 9 (a)). As a result, the internal volume of the air chamber 34 (not shown in FIG. 9) decreases.

  Thus, even if the adjustment air chamber 36 is directly driven by the heat deformable body so that the internal volume of the adjustment air chamber 36 can be continuously changed, the internal pressure of the air chamber 34 is always kept constant. Can keep. Thereby, even when the temperature change of the air chamber 34 (change in the ambient temperature of the ink supply device 10) occurs, the damper performance of the supply sub tank 18 can be kept constant, and the internal pressure of the supply flow path 12 can be maintained. Can be stably suppressed.

  Even when the adjustment air chamber 36 is directly driven by the heat deformable body, the initialization of the elastic film 22 in the main air chamber 26 may be performed in the same manner as in the first embodiment.

<Fourth Embodiment>
[Overall configuration of ink supply device]
The ink supply device 100 according to the fourth embodiment supplies ink stored in the ink tank 52 to the ink jet head 50 that is an ink supply target, and ink that has not been ejected by the ink jet head 50 to the ink tank 52. This is a circulation type ink supply device that collects and controls the internal pressure (negative pressure) of the inkjet head 50 by the amount of ink fed.

  FIG. 10 is a schematic diagram illustrating the overall configuration of the ink supply apparatus 100. In addition, the same code | symbol is attached | subjected to the part which is common in FIG. 1, and the detailed description is abbreviate | omitted. As shown in FIG. 10, the ink supply device 100 includes a recovery channel 112, recovery valves 114-1, 114-2,..., 114-n, dampers 115-1, 115-2,. A sensor 116, a collection sub tank 118, a collection pump 120, and the like are provided.

  The recovery channel 112 (an example of a liquid channel) communicates the inkjet head 50 and the ink tank 52 via a recovery pump 120, a recovery sub-tank 118, a manifold 154, and the like.

  Each of the head modules 51-1, 51-2,..., 51-n has an ink collection port 51B through which ink is collected. Each of the ink collection ports 51B of the head modules 51-1, 51-2,..., And 51-n includes dampers 115-1, 115-2, ..., 115-n, and collection valves 114-1, 114-2, respectively. ..., it communicates with the recovery channel 112 via 114-n.

  The recovery valves 114-1, 114-2,..., And 114-n are flow path opening / closing means for switching communication / blocking between the dampers 115-1, 115-2,. As the collection valves 114-1, 114-2,..., 114-n, normally closed or latch type electromagnetic valves whose opening / closing is controlled by a control signal are applied.

  The dampers 115-1, 115-2,..., And 115-n are used to discharge the nozzles of the head modules 51-1, 51-2,. It is a pressure adjusting means for suppressing pulsation of ink generated by opening and closing of 114-n.

  The pressure sensor 116 is a pressure measuring unit that measures the internal pressure of the recovery flow path 112, and is disposed between the manifold 154 and the recovery sub tank 118.

  The recovery sub tank 118 is a pressure adjusting unit that adjusts the pressure so as to suppress fluctuations in the internal pressure of the recovery flow path 112, and is configured in the same manner as the supply sub tank 18. That is, the recovery sub-tank 118 partitions the inside of the sealed container using the elastic film 122, and one side of the elastic film 122 is a liquid chamber 124 and the other side is a main air chamber 126. A material that is flexible and easily deformed is used for the elastic film 122.

  The recovery pump 120 is a liquid pressure applying unit that applies pressure to the ink inside the recovery flow path 112.

  .., And 51-n supplied to the head modules 51-1, 51-2,..., 51-n of the inkjet head 50 are dumped by the recovery pump 120 by the dampers 115-1, 115-2,. , 114-n, the manifold 154, and the recovery sub-tank 118, the ink is recovered into the ink tank 52.

  In the liquid chamber 124 of the recovery sub tank 118, an ink outlet 124A (an example of a circulation port) and an ink inlet 124B (an example of a circulation port) are provided. The ink outlet 124A is in communication with the recovery pump 120 via the recovery channel 112, and the ink inlet 124B is in communication with the manifold 54 via the recovery channel 112.

  When ink flows into the liquid chamber 124 from the ink inlet 124B, the elastic film 122 is deformed to the main chamber 126 side according to the volume of the ink that has flowed in. As a result, the volume of the ink flowing out from the ink outlet 124A does not change, and the flow rate of the ink flowing out from the liquid chamber 124 is constant. Therefore, the recovery sub tank 118 can suppress fluctuations in the internal pressure of the inkjet head 50 due to the discharge operation from the nozzles and fluctuations in the internal pressure of the recovery flow path 112 due to the pulsating flow due to the liquid feeding operation of the recovery pump 120. it can.

  In addition, the ink supply device 100 includes an air flow path 132, an adjustment air chamber 136, a thermistor 142, a linear stepping motor 144, and the like as a gas elasticity adjustment unit for determining the pressure adjustment performance of the recovery sub tank 118.

  The main air chamber 126 of the recovery sub-tank 118 is provided with an air flow passage communication port 126A, and the adjustment air chamber 136 is provided with an air flow passage communication port 136A. In addition, the air channel communication port 126A and the air channel communication port 136A communicate with the air channel 132. That is, the main air chamber 126 and the adjustment air chamber 136 communicate with each other through the air flow path 132, and form a space in which gas is sealed. A sealed space including the main air chamber 126, the air flow path 132, and the adjustment air chamber 136 is referred to as an air chamber 134 (an example of a gas chamber).

  The adjustment air chamber 136 has a bellows part 137 that can be expanded and contracted on the side wall. The adjustment air chamber 136 is configured such that the internal volume of the adjustment air chamber 136 can be continuously changed by continuously changing from the folded state of the bellows portion 137 (an example of the expansion / contraction portion) to the extended state. Has been.

  The thermistor 142 (an example of a temperature sensor) is a temperature measuring unit that measures the temperature of the air chamber 134. The measurement result of the thermistor 42 that measures the temperature of the main air chamber 26 may be the temperature of the air chamber 134.

  The linear stepping motor 144 includes a shaft 145 configured to reciprocate in a direction parallel to the side wall of the adjustment air chamber 136, and the shaft 145 is fixed to the upper wall 138 of the adjustment air chamber 136. The lower wall 139 of the adjustment air chamber 136 is supported and fixed at a fixed position. Therefore, when the linear stepping motor 144 is driven to reciprocate the shaft 145, the upper wall 138 reciprocates while the lower wall 139 of the adjustment air chamber 136 is fixed, and the bellows portion 137 on the side wall expands and contracts. Thereby, the internal volume of the adjustment air chamber 136 increases / decreases, and as a result, the internal volume of the air chamber 134 increases / decreases.

[System configuration of ink supply device]
As shown in FIG. 11, in the ink supply device 100, the measurement results of the pressure sensor 116 and the thermistor 142 are input to the control unit 46. In addition, the control unit 46 controls the collection valves 114-1, 114-2, ..., 114-n, the collection pump 120, and the linear stepping motor 144.

[Ink supply pressure control]
The ink supply pressure control of the ink supply apparatus 100 may be performed in the same manner as the flowchart shown in FIG. Further, the pressure control for ink recovery may be performed in accordance with the pressure control for ink supply.

That is, first initializes the elastic membrane 122 (step S1), the memory 48 then the elapsed time t is initialized to an initial time _{t 0} (the step S2) the initial temperature _T 0 [K] is obtained from the thermistor 142 (Step S3).

Thereafter, timed with a timer 49 (step S4), and When the elapsed time t becomes the temperature measurement time _{t 1} (step S5), and acquires the temperature of the air chamber 134 from the thermistor 142, the current temperature T of the acquired temperature ₁ [K] is stored in the memory 48 (step S6). Then, the current temperature T ₁ of the initial temperature T ₀ is stored in the memory 48., determines whether a temperature change of the air chamber 134 from the time of setting the volume of the air chamber 134 (step S7).

If the temperature of the air chamber 134 has not changed since the volume of the air chamber 134 was set, the elapsed time t is initialized to the initial time t ₀ (step S8), and the same processing is repeated until the print job is completed.

  On the other hand, when the temperature of the air chamber 134 has changed since the volume of the air chamber 134 was set, the internal pressure of the air chamber 134 is controlled to be constant by changing the volume of the adjusted air chamber 136.

  Using the gas equation of state, a change amount ΔV of the volume of the air chamber 134 for keeping the internal pressure of the air chamber 134 constant (atmospheric pressure) is calculated (step S9), and a change amount ΔV of the volume of the air chamber 134 is calculated. The expansion amount or the reduction amount of the bellows part 137 of the adjustment air chamber 136 corresponding to is calculated, and the calculated extension amount or reduction amount of the bellows part 137 is converted into the driving direction and the driving amount of the linear stepping motor 144 (step S10). .

  Further, the linear stepping motor 144 is driven based on the driving direction and driving amount of the linear stepping motor 144, the bellows part 137 of the adjustment air chamber 136 is expanded or contracted, the volume of the air chamber 134 is changed by ΔV, and the air chamber is changed. The internal pressure of 134 is maintained at the pressure (atmospheric pressure) before the temperature change.

Then, it initializes the initial temperature T ₀ to the current temperatures T ₁ with (step S12), the initializing the elapsed time t to an initial time t ₀ (step S8), and repeats the same processing until the print job ends.

  By controlling the volume of the air chamber 134 as described above, the internal pressure of the air chamber 134 can always be kept constant while the inkjet head 50 is operating. Therefore, even when the temperature of the air chamber 134 changes (change in the ambient temperature of the ink supply device 10), the damper performance of the recovery sub tank 118 can be kept constant, and the internal pressure of the recovery flow path 112 can be maintained. The fluctuation can be stably suppressed.

<Fifth Embodiment>
[Overall configuration of inkjet recording apparatus]
As shown in FIG. 12, an inkjet recording apparatus 200 (an example of a liquid ejection apparatus) is a single-wafer type aqueous inkjet printer that records an image by an inkjet method using aqueous ink on paper P (corresponding to a medium).

  As shown in FIG. 12, the ink jet recording apparatus 200 delivers conveyance drums 210, 212, and 214 that sequentially deliver and convey the paper P, and cyan (C), magenta (M), yellow (Y), and black (K) on the paper P. ) Ink supply devices 250C and 250M that supply ink of each color of cyan, magenta, yellow, and black to inkjet heads 240C, 240M, 240Y, and 240K and inkjet heads 240C, 240M, 240Y, and 240K, respectively, that discharge ink droplets of , 250Y, 250K, and the like.

  The transport drums 210, 212, and 214 are formed in a cylindrical shape, and are driven by a motor (not shown) to rotate around the center of the cylinder. The transport drum 210 transports the paper P fed from a paper feed unit (not shown) and delivers it to the transport drum 212. The conveyance drum 212 delivers the paper P delivered from the conveyance drum 210 to the conveyance drum 214. The transport drum 214 transports the paper P delivered from the transport drum 212 to a paper discharge unit (not shown).

  The inkjet head 50 shown in FIG. 1 can be applied to the inkjet heads 240C, 240M, 240Y, and 240K. The inkjet heads 240 </ b> C, 240 </ b> M, 240 </ b> Y, and 240 </ b> K are disposed so as to be substantially orthogonal to the conveyance direction of the paper P by the conveyance drum 212 and disposed so that the nozzle surface faces the outer peripheral surface of the conveyance drum 212. . The inkjet heads 240C, 240M, 240Y, and 240K are configured to transfer a conveyance drum from a nozzle (not shown) formed on the nozzle surface based on a control signal of the recording control unit 230 (an example of a discharge control unit, see FIG. 13). By ejecting ink droplets of cyan, magenta, yellow, and black, respectively, toward 212, an image is recorded on the recording surface of the paper P that is transported by the transport drum 212 (an example of a moving unit).

  The ink supply devices 250C, 250M, 250Y, and 250K (an example of a supply unit and a collection unit) supply inks of cyan, magenta, yellow, and black to the inkjet heads 240C, 240M, 240Y, and 240K, respectively. As the ink supply devices 250C, 250M, 250Y, and 250K, the ink supply device 10 and the ink supply devices 60, 70, and 100 described so far can be appropriately applied.

  The ink jet recording apparatus 200 configured as described above receives the paper P transported by the transport drum 210 by the transport drum 212 and transports the paper P by the transport drum 212. Each of the inkjet heads 240C, 240M, 240Y, and 240K applies ink droplets of cyan, magenta, yellow, and black to the recording surface of the paper P when the paper P passes through the opposing positions. A color image is recorded on the recording surface. At this time, the ink supply devices 250C, 250M, 250Y, and 250K eliminate the influence of temperature change and supply ink to the inkjet heads 240C, 240M, 240Y, and 240K while performing stable pressure control of the ink flow path.

  Thereafter, the transport drum 212 delivers the paper P to the transport drum 214. The paper P is transported to a paper discharge unit (not shown) by the transport drum 214 and is discharged from the paper discharge unit.

  In this way, by configuring the ink jet recording apparatus 200, the internal pressures of the ink flow paths of the ink supply apparatuses 250C, 250M, 250Y, and 250K and the internal pressures of the ink jet heads 240C, 240M, 240Y, and 240K can be controlled to be constant. Can do. Therefore, the inkjet heads 240C, 240M, 240Y, and 240K can be stably operated, and high-quality images can be recorded.

  The liquid ejecting apparatus according to the present invention is not limited to the ink jet recording apparatus 200 as an image recording apparatus, and can be applied to an apparatus having a head for ejecting liquid, such as a 3D printer or an ink jet electronic circuit wiring apparatus. It is.

  The technical scope of the present invention is not limited to the scope described in the above embodiment. The configurations and the like in the respective embodiments can be appropriately combined among the respective embodiments without departing from the spirit of the present invention.

  10, 60, 70, 100, 250C, 250M, 250Y, 250K ... ink supply device, 12 ... supply flow path, 16, 116 ... pressure sensor, 18 ... supply sub tank, 20 ... supply pump, 22, 122 ... elastic membrane, 24, 124 ... Liquid chamber, 26, 126 ... Main air chamber, 32, 132 ... Air flow path, 34, 134 ... Air chamber, 36, 136 ... Adjusted air chamber, 37, 137 ... Bellows section, 42, 142 ... Thermistor , 43, 143 ... Pressure sensor, 44, 144 ... Linear stepping motor, 45, 145 ... Shaft, 46 ... Control unit, 48 ... Memory, 50, 240C, 240M, 240Y, 240K ... Inkjet head, 62 ... Cylinder unit, 64 ... Piston part, 80 ... Bimetal, 82 ... First metal plate, 84 ... Second metal plate, 112 ... Recovery flow path, 118 ... Recovery sub tank 120 ... recovery pump

Claims (14)

A liquid flow path that connects a liquid discharge head that discharges liquid from the nozzle and a liquid tank that stores liquid;
A pump provided in the liquid flow path for applying pressure to the liquid in the liquid flow path;
Pressure adjusting means provided between the liquid discharge head and the pump, a liquid chamber communicating with the liquid flow path through a flow port, a variable volume gas chamber sealed with gas, An elastic membrane that separates the liquid chamber and the gas chamber;
A sensor for measuring the state of the gas chamber and outputting a measurement value;
Volume changing means for keeping the pressure inside the gas chamber constant by changing the volume of the gas chamber according to the measured value;
A liquid supply apparatus comprising: Storage means for storing an initial value of the measured value;
A change amount calculating means for calculating a measured value change amount with respect to the initial value from a newly measured value;
A volume change amount calculating means for calculating a change amount of the volume of the gas chamber for setting the pressure inside the gas chamber to the pressure at the time of measurement of the initial value from the calculated measurement value change amount;
A liquid supply apparatus according to claim 1. The gas chamber has an expandable portion that can change the volume of the gas chamber by expanding and contracting,
The liquid supply device according to claim 2, wherein the volume changing unit continuously changes the volume of the gas chamber by controlling expansion and contraction of the expansion and contraction unit.   The liquid supply apparatus according to claim 3, wherein the volume changing unit includes a linear stepping motor that expands and contracts an expansion / contraction portion of the gas chamber. Drive amount calculation means for calculating the drive direction and drive amount of the linear stepping motor from the calculated change amount of the volume of the gas chamber,
The liquid supply apparatus according to claim 4, wherein the volume changing unit drives the linear stepping motor by the calculated drive amount in the calculated drive direction.   The liquid supply apparatus according to claim 5, wherein the change amount of the volume and the drive amount of the linear stepping motor have a linear relationship.   The liquid supply apparatus according to any one of claims 3 to 6, wherein the expansion / contraction part has a bellows part that can be expanded and contracted.   The liquid supply apparatus according to claim 3, wherein the expansion / contraction part has a cylinder part having a cylinder structure.   The liquid supply device according to claim 1, wherein the sensor is a temperature sensor that outputs a temperature of the gas chamber as the measurement value.   The liquid supply device according to claim 1, wherein the sensor is a pressure sensor that outputs the pressure of the gas chamber as the measurement value. The gas chamber is
A first gas chamber having a constant volume and separated from the liquid chamber by the elastic membrane;
A variable volume second gas chamber in communication with the first gas chamber;
The liquid supply apparatus according to claim 1, comprising: The liquid chamber and the first gas chamber are integrally formed,
The liquid supply apparatus according to claim 11, wherein the first gas chamber and the second gas chamber communicate with each other through a communication path. A liquid tank for storing liquid;
A liquid discharge head for discharging liquid from a nozzle;
13. A supply means using the liquid supply apparatus according to claim 1, wherein the liquid tank is disposed between the liquid tank and the liquid discharge head, and stores the liquid stored in the liquid tank. Supply means for supplying to the liquid discharge head;
Moving means for relatively moving the liquid discharge head and the medium;
Discharge control means for applying liquid to the medium by discharging liquid from the nozzles of the liquid discharge head while relatively moving the medium;
A liquid ejection apparatus comprising:   13. A recovery unit using the liquid supply apparatus according to claim 1, wherein the liquid supply device is disposed between the liquid discharge head and the liquid tank, and supplies the liquid supplied to the liquid discharge head. The liquid ejection apparatus according to claim 13, further comprising a collection unit that collects the liquid in the liquid tank.