EP4219171A1

EP4219171A1 - Liquid circulating device and liquid ejecting device

Info

Publication number: EP4219171A1
Application number: EP22206803.3A
Authority: EP
Inventors: Satoshi Miura
Original assignee: Toshiba TEC Corp
Current assignee: Toshiba TEC Corp
Priority date: 2022-01-26
Filing date: 2022-11-10
Publication date: 2023-08-02
Also published as: JP2023109066A

Abstract

According to one embodiment, a liquid circulating device (30) includes a first pump (33), a second pump (36), a filter (52), a buffer tank (35), a pressure sensor (39), and a control unit. The first pump (33) is configured to supply a liquid of a liquid replenishment tank (51) to a liquid ejecting head (20). The second pump (36) is configured to collect the liquid from the liquid ejecting head (20) and to supply the liquid to the liquid replenishment tank (51). The filter (52) is provided in a flow path between the liquid replenishment tank (51) and the liquid ejecting head (20). The buffer tank (35) is connected to a flow path between the filter (52) and the liquid ejecting head (20) and a flow path between the liquid ejecting head (20) and the second pump (36), and the liquid ejected from the first pump (33) flows into the buffer tank (35). The pressure sensor (39) is configured to detect an internal pressure of the buffer tank (35). The control unit is configured to determine clogging of the filter (52) based on a drive voltage of the second pump (36) during adjustment circulation where a nozzle surface pressure of the liquid ejecting head (20) is adjusted based on the pressure of the buffer tank (35).

Description

FIELD

Embodiments described herein relate generally to a liquid circulating device and a liquid ejecting device.

BACKGROUND

In the related art, in a liquid ejecting device that ejects liquid, a liquid circulating device that circulates liquid using two pumps is known. A filter for, for example, removing foreign matter is connected to any one of the inside and the outside of the liquid circulating device. This filter is clogged due to various factors, but this clogging cannot be detected. As a method of detecting the clogging of the filter, a method of detecting a decrease in circulation flow rate using a flow rate sensor or a plurality of pressure sensors can be used. However, there is a concern such as an increase in cost and device size due to an increase in the number of components and spatial restrictions.

DISCLOSURE OF THE INVENTION

To this end, there is provided a liquid circulating device for a liquid ejecting device comprising a liquid ejecting head and liquid replenishment tank. The device comprises a first pump configured to supply a liquid of the liquid replenishment tank to the liquid ejecting head; a second pump configured to collect the liquid from the liquid ejecting head and to supply the liquid to the liquid replenishment tank; a filter provided in a flow path between the liquid replenishment tank and the liquid ejecting head; a buffer tank that is connected to a flow path between the filter and the liquid ejecting head and a flow path between the liquid ejecting head and the second pump and to which the liquid ejected from the first pump flows in; and a pressure sensor configured to detect an internal pressure of the buffer tank; and a control unit configured to determine clogging of the filter based on a drive voltage of the second pump during adjustment circulation where a nozzle surface pressure of the liquid ejecting head is adjusted based on the pressure of the buffer tank.
Preferably, if an output of the first pump is higher than or equal to a first threshold and an output of the second pump is lower than or equal to a second threshold, the control unit determines that clogging occurs in the filter.
Preferably, if the state where the output of the second pump is lower than or equal to the second threshold continues for a predetermined period of time, the control unit determines that clogging occurs in the filter.
In one embodiment, the filter is provided in a flow path between the first pump and the liquid ejecting head.
In one embodiment, the filter is provided in a flow path between the liquid replenishment tank and the first circulating pump.
In one embodiment, the filter is an external filter provided outside the device.
In one embodiment, the liquid circulating device is provided with the liquid replenishment tank.
The present invention further relates to a liquid ejecting device. The liquid ejecting device comprises the above-described liquid circulating device, the liquid replenishment tank connected to the first pump, the liquid ejecting head; and an external filter provided between the liquid circulating device and the liquid replenishment tank.
The present invention further relates to a printer including the liquid ejecting device.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a configuration example of a printer according to one embodiment;
FIG. 2 is a diagram illustrating a configuration example of a liquid ejecting device;
FIG. 3 is a diagram illustrating a configuration example of a liquid ejecting head;
FIG. 4 is a diagram illustrating a configuration example of a piezoelectric pump;
FIG. 5 is a diagram illustrating a configuration example of a module control unit;
FIG. 6 is a flowchart illustrating a control of a nozzle surface pressure by the module control unit;
FIG. 7 is a flowchart illustrating a filter clogging determination process;
FIG. 8 is a diagram illustrating an example of an output of a pressurization pump and an output of a depressurization pump if clogging occurs in an internal filter of a liquid circulating device; and
FIG. 9 is a diagram illustrating an example of an output of the pressurization pump and an output of the depressurization pump if clogging occurs in an external filter of the liquid circulating device.

DETAILED DESCRIPTION

Embodiments provide a liquid circulating device and a liquid ejecting device where clogging of a filter can be detected.
In general, according to one embodiment, a liquid circulating device includes a first pump, a second pump, a filter, a buffer tank, a pressure sensor, and a control unit. The first pump is configured to supply a liquid of a liquid replenishment tank to a liquid ejecting head. The second pump is configured to collect the liquid from the liquid ejecting head and to supply the liquid to the liquid replenishment tank. The filter is provided in a flow path between the liquid replenishment tank and the liquid ejecting head. The buffer tank is connected to a flow path between the filter and the liquid ejecting head and a flow path between the liquid ejecting head and the second pump, and the liquid ejected from the first pump flows into the buffer tank. The pressure sensor is configured to detect an internal pressure of the buffer tank. The control unit is configured to determine clogging of the filter based on a drive voltage of the second pump during adjustment circulation where a nozzle surface pressure of the liquid ejecting head is adjusted based on the pressure of the buffer tank.
Hereinafter, a liquid circulating device 30 according to an embodiment, a liquid ejecting device 10 including the liquid circulating device 30, and a printer 1 including the liquid ejecting device 10 will be described with reference to FIGS. 1 to 9. In each of the drawings, configurations are illustrated in an enlarged or contracted manner or are not illustrated for convenience of description. FIG. 1 is a side view schematically illustrating a configuration of the printer 1. FIG. 2 is a diagram illustrating a configuration of the liquid ejecting device 10. FIG. 3 is a diagram illustrating a configuration of a liquid ejecting head 20. FIG. 4 is a diagram illustrating a configuration of a first circulating pump 33 and a second circulating pump 36.
The printer 1 illustrated in FIG. 1 includes: a plurality of liquid ejecting devices 10; a head support mechanism 11 that movably supports the liquid ejecting devices 10; a medium support mechanism 12 that movably supports a recording medium S; and a host control device 13. The printer 1 is an ink jet recording apparatus that ejects an ink as a liquid.
The liquid ejecting device 10 ejects, for example, an ink I as a liquid from the liquid ejecting head 20 to form a desired image on the recording medium S that is disposed to face the liquid ejecting device 10. As illustrated in FIG. 1, the plurality of liquid ejecting devices 10 are arranged in parallel in a predetermined direction and are supported by a head support mechanism 11. The liquid ejecting device 10 includes the liquid ejecting head 20 and the liquid circulating device 30 that are integrated. In addition, the liquid ejecting device 10 includes: a cartridge 51 as an ink replenishment tank (liquid replenishment tank); and an external filter 52 that is provided in a flow path between the cartridge 51 and the first circulating pump 33. For example, the cartridge 51 and the external filter 52 are replaceably formed. The cartridge 51 is configured to contain the ink, in which an air chamber is open to the atmosphere. The external filter 52 removes foreign matter in the ink.
The liquid ejecting device 10 may be configured to include a liquid replenishment tank 51 that can be replenished with a liquid instead of the replaceable cartridge 51. The liquid replenishment tank 51 and the external filter 52 may be configured to be provided to be integrated in the liquid circulating device 30.
The plurality of liquid ejecting devices 10 eject a plurality of colors, for example, cyan ink, magenta ink, yellow ink, black ink, and white ink, respectively. However, the colors or characteristics of the inks I to be used are not particularly limited. For example, a transparent gloss ink or a special ink that is colored when irradiated with infrared light or ultraviolet light can be ejected instead of white ink. The plurality of liquid ejecting devices 10 use different inks but have the same configuration.
First, the liquid ejecting head 20 will be described.
The liquid ejecting head 20 illustrated in FIG. 3 is an inkjet head and includes: a supply port 201 to which ink flows in; a collection port 202 from which ink flows out; a nozzle plate 21 that includes a plurality of nozzle holes 211; a substrate 22; and a manifold 23 that is joined to the substrate 22.
The substrate 22 is joined to face the nozzle plate 21 and is configured in a predetermined shape in which a predetermined ink flow path 28 including a plurality of ink pressure chambers 25 is formed between the substrate 22 and the nozzle plate 21. The substrate 22 includes partition walls that are disposed between the plurality of ink pressure chambers 25 in the same column. In a portion of the substrate 22 facing each of the ink pressure chambers 25, an actuator 24 including electrodes 241 and 242 is provided.
The actuator 24 is disposed to face the nozzle hole 211, and the ink pressure chamber 25 is formed between the actuator 24 and the nozzle hole 211. The actuator 24 is connected to a drive circuit. The liquid ejecting head 20 ejects the liquid from the nozzle hole 211 that is disposed to face the liquid ejecting head 20 if the actuator 24 is controlled by a module control unit 38 to be deformed in accordance with a voltage.
Next, the liquid circulating device 30 will be described.
As illustrated in FIG. 2, the liquid circulating device 30 is integrally connected to an upper portion of the liquid ejecting head 20 through a connection component formed of a metal. The liquid circulating device 30 includes: a predetermined circulation flow path 31 that is configured such that the liquid flowing through the liquid ejecting head 20 can be circulated; the first circulating pump 33; a bypass flow path 34; a buffer tank 35 as a buffer device 100; the second circulating pump 36; an opening and closing valve 37, and the module control unit 38 that controls a liquid ejection operation.
First, the circulation flow path 31 will be described.
The circulation flow path 31 includes a first flow path 311, a second flow path 312, a third flow path 313, and a fourth flow path 314. In addition, the circulation flow path 31 includes a filter 315. The first flow path 311 connects the cartridge 51 as the ink replenishment tank and the first circulating pump 33. The second flow path 312 connects the first circulating pump 33 and the supply port 201 of the liquid ejecting head 20. The third flow path 313 connects the collection port 202 of the liquid ejecting head 20 and the second circulating pump 36. The fourth flow path 314 connects the second circulating pump 36 and the cartridge 51.
The first flow path 311 and the fourth flow path 314 include: a pipe that is formed of a metal or a resin material; and a tube that covers an external surface of the pipe. The tube that covers the external surface of the pipe of the first flow path 311 and the fourth flow path 314 is, for example, a PTFE tube. The filter 315 is provided in a primary flow path of the liquid ejecting head 20 in a direction in which the ink flows, for example, in the first flow path 311 or the second flow path 312.
In a specific example, the filter 315 is provided in the second flow path 312. In addition, the filter 315 is provided on the primary side (first circulating pump 33 side) of the second flow path 312 further than the bypass flow path 34 connected to the second flow path 312. The filter 315 filters the ink. The filter 315 removes foreign matter in the ink. The filter 315 is an internal filter provided in the liquid circulating device 30. Hereinafter, for convenience of description, the filter 315 is described as the internal filter 315.
The ink that circulates in the circulation flow path 31 arrives at the inside of the liquid ejecting head 20 from the cartridge 51 through the first flow path 311, the first circulating pump 33, the second flow path 312, and the supply port 201 of the liquid ejecting head 20. In addition, the ink that circulates in the circulation flow path 31 arrives at the cartridge 51 from the liquid ejecting head 20 through the collection port 202 of the liquid ejecting head 20, the third flow path 313, the second circulating pump 36, and the fourth flow path 314.
Next, the first circulating pump (first pump) 33 and the second circulating pump (second pump) 36 will be described.
The first circulating pump 33 is a pump that supplies the liquid. The first circulating pump 33 supplies the liquid from the first flow path 311 toward the second flow path 312. That is, the first circulating pump 33 is a pressurization pump that sucks up the ink from the cartridge 51 as the ink replenishment tank through the operation of the actuator and supplies the ink to the liquid ejecting head 20.
The second circulating pump 36 is a pump that supplies the liquid. The second circulating pump 36 supplies the liquid from the third flow path 313 toward the fourth flow path 314. That is, the second circulating pump 36 is a depressurization pump that collects the ink from the liquid ejecting head 20 through the operation of the actuator and replenishes the cartridge 51 with the ink.
The first circulating pump 33 and the second circulating pump 36 are configured as a piezoelectric pump 60, for example, as illustrated in FIG. 4. The piezoelectric pump 60 includes: a pump chamber 58; a piezoelectric actuator 59 that is provided in the pump chamber 58 and vibrates in accordance with a voltage; and check valves 61 and 62 that are disposed at an entry and an exit of the pump chamber 58. The piezoelectric actuator 59 is configured to vibrate at a frequency of, for example, about 50 Hz to 200 Hz. The first circulating pump 33 and the second circulating pump 36 are configured to be controlled by the control of the module control unit 38 connected to the drive circuit through a wiring.
For example, by changing the voltage applied to the piezoelectric actuator 59, the piezoelectric actuator 59 is deformed in a direction in which the pump chamber 58 is contracted or in a direction in which the pump chamber 58 is expanded as illustrated in the lower diagram and the upper diagram of FIG. 4. As a result, the volume of the pump chamber 58 changes. For example, if the piezoelectric actuator 59 is deformed in the direction in which the pump chamber 58 is expanded, the check valve 61 of the entry of the pump chamber 58 is opened such that the ink flows into the pump chamber 58. In addition, for example, if the piezoelectric actuator 59 is deformed in the direction in which the pump chamber 58 is contracted, the check valve 62 of the exit of the pump chamber 58 is opened such that the ink of the pump chamber 58 is supplied to another part. By repeating this operation, the first circulating pump 33 and the second circulating pump 36 receive the ink flowing in from one side and supply the ink from another side.
The maximum amount of change of the piezoelectric actuator 59 corresponds to the voltage applied to the piezoelectric actuator 59. As the voltage applied to the piezoelectric actuator 59 increases, the maximum amount of change of the piezoelectric actuator 59 increases. In addition, as the voltage applied to the piezoelectric actuator 59 decreases, the maximum amount of change of the piezoelectric actuator 59 decreases. In addition, the liquid supply capacity of the piezoelectric pump 60 corresponds to the maximum amount of change of the piezoelectric actuator 59. That is, the module control unit 38 controls the liquid supply capacity of the piezoelectric pump 60 by controlling the voltage applied to the piezoelectric actuator 59.
Next, the bypass flow path 34 and the buffer tank 35 will be described.
The bypass flow path 34 is a flow path that connects the second flow path 312 and the third flow path 313. The bypass flow path 34 bypasses the liquid ejecting head 20 and connects the supply port 201 on the primary side of the liquid ejecting head 20 and the collection port 202 on the secondary side of the liquid ejecting head 20 in the circulation flow path 31.
The buffer tank 35 is connected to the bypass flow path 34. Specifically, the bypass flow path 34 includes: a first bypass flow path 341 that connects a predetermined portion of a lower part of a pair of side walls of the buffer tank 35 and the second flow path 312; and a second bypass flow path 342 that connects a predetermined portion of a lower part of the pair of side walls of the buffer tank 35 and the third flow path 313.
For example, the first bypass flow path 341 and the second bypass flow path 342 have the same length and the same diameter and are also configured to have a smaller diameter than the circulation flow path 31. For example, the diameter of the circulation flow path 31 is set to be about 2 times to 5 times the diameter of the first bypass flow path 341 and the second bypass flow path 342. The first bypass flow path 341 and the second bypass flow path 342 are provided such that the distance from a connection position between the second flow path 312 and the first bypass flow path 341 to the supply port 201 of the liquid ejecting head 20 is the same as the distance from a connection position between the third flow path 313 and the second bypass flow path 342 to the collection port 202 of the liquid ejecting head 20.
The buffer tank 35 has a flow path cross-sectional area that is larger than the flow path cross-sectional area of the bypass flow path 34 and is configured to store the liquid. The buffer tank 35 includes, for example, an upper wall, a lower wall, a rear wall, a front wall, and a pair of right and left side walls and is configured in a rectangular box shape in which a storage chamber 351 that stores the liquid is formed. The connection position between the first bypass flow path 341 and the buffer tank 35 and the connection position between the second bypass flow path 342 and the buffer tank 35 are set at the same height. In a lower region of the storage chamber 351 of the buffer tank 35, the ink flowing through the bypass flow path 34 is disposed. In an upper region of the storage chamber 351, an air chamber is formed. That is, the buffer tank 35 can store predetermined amounts of the liquid and air. In addition, in the buffer tank 35, the opening and closing valve 37 and a pressure sensor 39 are provided, the opening and closing valve 37 being configured such that the air chamber in the buffer tank 35 can be open to the atmosphere.
For example, the opening and closing valve 37 is a normally closed solenoid opening and closing valve that is opened if the power is turned on and is closed if the power is turned off. The opening and closing valve 37 is configured to open and close the air chamber of the buffer tank 35 to and from the atmosphere by being controlled to be opened and closed by the module control unit 38. That is, the buffer tank 35 is open to the atmosphere by opening the opening and closing valve 37.
The pressure sensor 39 detects a pressure of the air chamber in the buffer tank 35 and transmits pressure data representing the pressure value to the module control unit 38. If the opening and closing valve 37 is opened and the air chamber of the buffer tank 35 is open to the atmosphere, the pressure data detected by the pressure sensor 39 is the same as the atmospheric pressure. The pressure sensor 39 detects a pressure of the air chamber of the buffer tank 35 if the opening and closing valve 37 is closed and the air chamber of the buffer tank 35 is not open to the atmosphere.
The pressure sensor 39 outputs the pressure as an electrical signal, for example, using a semiconductor piezoresistance pressure sensor. The semiconductor piezoresistance pressure sensor includes: a diaphragm that receives a pressure from the outside; and a semiconductor strain gauge that is formed on a surface of the diaphragm. The semiconductor piezoresistance pressure sensor converts a change in electrical resistance due to the piezoresistance effect into an electrical signal to detect the pressure, the piezoresistance effect occurring in the strain gauge along with the deformation of the diaphragm by the pressure from the outside.
Next, the module control unit 38 will be described.
FIG. 5 is a diagram illustrating a configuration example of the module control unit 38.
The module control unit 38 controls the operations of the liquid ejecting head 20, the first circulating pump 33, the second circulating pump 36, and the opening and closing valve 37. The module control unit 38 includes a central processing unit (CPU) 71, a memory 72, a communication interface 73, a circulating pump drive circuit 74, a valve drive circuit 76, and a liquid ejecting head drive circuit 77.
The CPU 71 is an arithmetic element (for example, a processor) that executes arithmetic processing. The CPU 71 is a control unit that executes various processes based on data such as programs stored in the memory 72. The CPU 71 is a processing circuit that can execute various controls by executing the programs stored in the memory 72.
The memory 72 is a memory device that stores various information. The memory 72 includes a read only memory (ROM) 721 and a random access memory (RAM) 722.
The ROM 721 is a nonvolatile memory for read only. The ROM 721 stores the program and the data used in the program. For example, the ROM 721 stores, as control data used for the pressure control, a calculation formula for calculating the ink pressure of the nozzle hole 211, a set pressure range, and various set values such as a first threshold, a second threshold, a third threshold, and a fourth threshold.
The first threshold is, for example, an adjustment maximum value of the first circulating pump 33 as the pressurization pump. The second threshold is, for example, an adjustment maximum value of the second circulating pump 36 as the depressurization pump. The third threshold is a threshold for determining that clogging occurs in any one of the external filter 52 and the internal filter 315. The third threshold is, for example, an output value of the first circulating pump 33 and/or the second circulating pump 36 if clogging occurs in the external filter 52 and the internal filter 315. For example, the third threshold is a minimum value (adjustment minimum value) of a drive voltage at which the piezoelectric actuator 59 of the second circulating pump 36 can operate.
The fourth threshold is a period of time required to determine that clogging occurs in the external filter 52 and the internal filter 315. The fourth threshold is a period of time required to determine that clogging occurs in the external filter 52 and the internal filter 315, for example, if the output of the second circulating pump 36 reaches the third threshold and subsequently is maintained. In the example of the embodiment, the fourth threshold is, for example, 10 seconds.
The RAM 722 is a volatile memory that functions as a working memory. The RAM 722 temporarily stores data or the like that is being processed by the CPU 71. In addition, the RAM 722 temporarily stores the program that is executed by the CPU 71.
The communication interface 73 is an interface for communication with another device. The communication interface 73 relays, for example, communication with the host control device 13 that transmits print data to the liquid ejecting device 10.
The circulating pump drive circuit 74 applies the drive voltage to the piezoelectric actuator 59 of the piezoelectric pump 60 to drive the piezoelectric pump 60 in accordance with the control of the CPU 71. As a result, the circulating pump drive circuit 74 circulates the ink in the circulation flow path 31. The circulating pump drive circuit 74 is provided for each of the circulating pumps. The circulating pump drive circuit 74 connected to the first circulating pump 33 applies the drive voltage to the piezoelectric actuator 59 of the first circulating pump 33. The circulating pump drive circuit 74 connected to the second circulating pump 36 applies the drive voltage to the piezoelectric actuator 59 of the second circulating pump 36.
The valve drive circuit 76 drives the opening and closing valve 37 in accordance with the control of the CPU 71 such that the air chamber of the buffer tank 35 is open to the atmosphere.
The liquid ejecting head drive circuit 77 applies the voltage to the actuator 24 of the liquid ejecting head 20 to drive the liquid ejecting head 20 in accordance with the control of the CPU 71, and ejects the ink from the nozzle holes 211 of the liquid ejecting head 20.
In the above-described configuration, the CPU 71 receives various information such as operation conditions by communicating with the host control device 13 as an external terminal via the communication interface 73. In addition, the various information acquired by the CPU 71 are transmitted to the host control device 13 of the printer 1 via the communication interface 73.
In addition, the CPU 71 acquires the detection result from the pressure sensor 39 and controls the operations of the circulating pump drive circuit 74 and the valve drive circuit 76 based on the acquired detection result. For example, the CPU 71 controls the liquid supply capacities of the first circulating pump 33 and the second circulating pump 36 by controlling the circulating pump drive circuit 74 based on the detection result of the pressure sensor 39. As a result, the CPU 71 adjusts the ink pressure of the nozzle hole 211.
In addition, the CPU 71 controls the valve drive circuit 76 such that the opening and closing valve 37 is opened and closed. As a result, the CPU 71 adjusts the liquid level of the buffer tank 35.
In addition, the CPU 71 acquires the detection result from the pressure sensor 39 and controls the liquid ejecting head drive circuit 77 based on the acquired detection result such that the ink droplets are ejected from the nozzle holes 211 of the liquid ejecting head 20 to the recording medium. Specifically, the CPU 71 inputs an image signal corresponding to image data to the liquid ejecting head drive circuit 77. The liquid ejecting head drive circuit 77 drives the actuator 24 of the liquid ejecting head 20 in accordance with the image signal. If the liquid ejecting head drive circuit 77 drives the actuator 24 of the liquid ejecting head 20, the actuator 24 is deformed such that the ink pressure (nozzle surface pressure) of the nozzle hole 211 at a position facing the actuator 24 changes. The nozzle surface pressure is a pressure that is applied by the ink of the ink pressure chamber 25 to a meniscus Me formed by the ink in the nozzle hole 211. If the nozzle surface pressure exceeds a predetermined value that is determined depending on the shape of the nozzle holes 211, the characteristics of the ink, and the like, the ink is ejected from the nozzle holes 211. As a result, the CPU 71 forms an image corresponding to the image data on the recording medium.
In addition, based on the detection result of the pressure sensor 39, the CPU 71 executes an ink shortage determination process of determining whether the cartridge 51 as the ink replenishment tank is likely to be short of ink.
Next, the control of the nozzle surface pressure by the CPU 71 of the module control unit 38 will be described.
If the printing is not executed, the CPU 71 maintains the nozzle surface pressure of the nozzle holes 211 of the liquid ejecting head 20 to be a negative pressure in order to prevent the ink droplets from dropping from the nozzle holes 211 of the liquid ejecting head 20. In addition, during printing, the CPU 71 maintains a sufficient nozzle surface pressure (pressure for maintaining the meniscus Me) for ejecting the ink droplets from the nozzle holes 211 of the liquid ejecting head 20. The CPU 71 controls the nozzle surface pressure of the nozzle holes 211 of the liquid ejecting head 20 by controlling the liquid supply capacities of the first circulating pump 33 and the second circulating pump 36.
The nozzle surface pressure is increased or decreased based on a relationship between the liquid supply capacity of the first circulating pump 33 and the liquid supply capacity of the second circulating pump 36. Specifically, if the liquid supply capacity of the first circulating pump 33 is higher than the liquid supply capacity of the second circulating pump 36, the nozzle surface pressure is increased. In addition, if the liquid supply capacity of the first circulating pump 33 is lower than the liquid supply capacity of the second circulating pump 36, the nozzle surface pressure is decreased.
FIG. 6 is a flowchart illustrating the control of the nozzle surface pressure by the CPU 71 of the module control unit 38.
The CPU 71 waits for a circulation start instruction in ACT 1. For example, if the circulation start instruction from the host control device 13 is detected (ACT 1, YES), the CPU 71 proceeds to the process of ACT 2. In a printing operation, the host control device 13 executes the ink ejection operation while causing the liquid ejecting devices 10 to reciprocate in a direction perpendicular to a conveying direction of the recording medium S such that the image is formed on the recording medium S. Specifically, the CPU 71 conveys the carriage 111 provided in the head support mechanism 11 in a direction of the recording medium S to reciprocate the carriage 111 in an arrow A direction. In addition, the CPU 71 supplies the image signal corresponding to the image data to the liquid ejecting head drive circuit 77 to drive the actuator 24 of the liquid ejecting head 20 in accordance with the image signal such that the ink droplets are ejected from the nozzle holes 211 to the recording medium S.
In ACT 2, the CPU 71 drives the first circulating pump 33 and second circulating pump 36 to start the ink circulation operation. The ink that circulates in the circulation flow path 31 arrives at the inside of the liquid ejecting head 20 from the cartridge 51 through the first flow path 311, the first circulating pump 33, the second flow path 312, and the supply port 201 of the liquid ejecting head 20. In addition, the ink that circulates in the circulation flow path 31 arrives at the cartridge 51 from the liquid ejecting head 20 through the collection port 202 of the liquid ejecting head 20, the third flow path 313, the second circulating pump 36, and the fourth flow path 314.
In ACT 3, the CPU 71 detects the pressure data of the buffer tank 35 transmitted from the pressure sensor 39.
In ACT 4, the CPU 71 detects the ink pressure of the nozzle holes 211 from the pressure data. Specifically, the ink pressure of the nozzle holes 211 is calculated using a predetermined arithmetic expression based on the pressure data of the buffer tank 35 transmitted from the pressure sensor 39.
First, if an ink density is represented by p, a gravitational acceleration is represented by g, and a distance from the liquid level of the ink in the buffer tank 35 and the nozzle surface in the height direction is represented by h, a pressure generated by a water head difference between the liquid level of the ink in the buffer tank 35 and the height of the nozzle surface is represented by pgh. For example, the CPU 71 calculates an ink pressure(nozzle surface pressure) Pn of the nozzle by adding the pressure pgh to the pressure data of the buffer tank 35 transmitted from the pressure sensor 39.
By executing various comparisons based on the calculated nozzle surface pressure Pn, the CPU 71 controls the drive voltage applied to the piezoelectric actuator 59 of the first circulating pump 33 and the drive voltage applied to the piezoelectric actuator 59 of the second circulating pump 36 to control the liquid supply capacities of the first circulating pump 33 and the second circulating pump 36. As a result, the CPU 71 controls the nozzle surface pressure Pn to be an appropriate value.
The CPU 71 acquires the set pressure range as the target pressure of the set nozzle surface pressure Pn from the ROM 721. The set pressure range may be one value or may be configured to have an upper limit value and a lower limit value. In addition, the CPU 71 may be configured to acquire a sequential set pressure range from the host control device 13 via the communication interface 73. In the description of this example, it is assumed that the set pressure range is one value (set pressure).
First, in ACT 5, the CPU 71 determines whether or not the nozzle surface pressure Pn is lower than the set pressure.
If the CPU 71 determines that the nozzle surface pressure Pn is lower than the set pressure (ACT 5, YES), the CPU 71 determines whether or not the output of the first circulating pump 33 as the pressurization pump is higher than or equal to the adjustment maximum value (first threshold) in ACT 6. That is, the CPU 71 determines whether or not the drive voltage applied to the piezoelectric actuator 59 that configures the first circulating pump 33 as the pressurization pump is the maximum value (adjustment maximum value) of the drive voltage at which the piezoelectric actuator 59 can operate in the control of the nozzle surface pressure.
If the CPU 71 determines that the output of the first circulating pump 33 as the pressurization pump is the adjustment maximum value (ACT 6, YES), the CPU decreases the drive voltage of the second circulating pump 36 as the depressurization pump in ACT 7. That is, the CPU 71 decreases the liquid supply capacity of the second circulating pump 36. As a result, the nozzle surface pressure Pn is increased.
If the CPU 71 determines that the output of the first circulating pump 33 as the pump is not the adjustment maximum value (ACT 6, NO), the CPU 71 increases the drive voltage of the first circulating pump 33 in ACT 8. That is, the CPU 71 increases the liquid supply capacity of the first circulating pump 33. As a result, the nozzle surface pressure Pn is increased.
In addition, if the CPU 71 determines that the nozzle surface pressure Pn is higher than or equal to the set pressure (ACT 5, NO), in ACT 9, the CPU 71 determines whether or not the nozzle surface pressure Pn is higher than the set pressure.
If the CPU 71 determines that the nozzle surface pressure Pn is higher than the set pressure (ACT 9, YES), the CPU 71 determines whether or not the output of the second circulating pump 36 as the depressurization pump is higher than or equal to the adjustment maximum value (second threshold) in ACT 10. That is, the CPU 71 determines whether or not the drive voltage applied to the piezoelectric actuator 59 that configures the second circulating pump 36 as the depressurization pump is the maximum value at which the piezoelectric actuator 59 can operate in the control of the nozzle surface pressure.
If the CPU 71 determines that the output of the depressurization pump is the adjustment maximum value (ACT 10, YES), the CPU 71 decreases the drive voltage of the first circulating pump 33 in ACT 11. That is, the CPU 71 decreases the liquid supply capacity of the first circulating pump 33. As a result, the nozzle surface pressure Pn is decreased.
If the CPU 71 determines that the output of the depressurization pump is not the adjustment maximum value (ACT 10, NO), the CPU 71 increases the drive voltage of the second circulating pump 36 in ACT 12. That is, the CPU 71 increases the liquid supply capacity of the second circulating pump 36. As a result, the nozzle surface pressure Pn is decreased.
If the CPU 71 decreases the drive voltage of the second circulating pump 36 in ACT 7, if the CPU 71 increases the drive voltage of the first circulating pump 33 in ACT 8, if the CPU 71 decreases the drive voltage of the first circulating pump 33 in ACT 11, and if the CPU 71 increases the drive voltage of the second circulating pump 36 in ACT 12, the CPU 71 executes a filter clogging determination process in ACT 13. Here, the filter clogging determination process that is executed in ACT 13 is a function in which the CPU 71 determines that clogging occurs in any one of the external filter 52 and the internal filter 315.
If the CPU 71 executes the filter clogging determination process, the CPU 71 determines whether or not a circulation end instruction is output in the filter clogging determination process and whether or not the circulation end instruction is received from the host control device 13 in ACT 14. In addition, if the CPU 71 determines that the nozzle surface pressure Pn is not higher than the set pressure (ACT 9, NO), the CPU 71 proceeds to the process of ACT 14.
If the CPU 71 does not receive the circulation end instruction from the host control device 13 (ACT 14, NO), the CPU 71 proceeds to the process of ACT 3. That is, the CPU 71 repeatedly executes the processes of ACT 3 to ACT 13 until the circulation end instruction is received. As a result, the CPU 71 executes a sequential control such that the nozzle surface pressure Pn becomes the set pressure.
If the CPU 71 receives the circulation end instruction from the host control device 13 (ACT 14, YES), the CPU 71 ends the circulation of the ink in ACT 15. That is, the CPU 71 stops the operations of the first circulating pump 33 and the second circulating pump 36 by stopping the operation of the circulating pump drive circuit 74. As a result, the CPU 71 ends the circulation of the ink between the cartridge 51 and the circulation flow path 31.
Next, the filter clogging determination process in ACT 13 of FIG. 6 will be described using FIGS. 7 to 9. FIG. 7 is a flowchart illustrating one example of the filter clogging determination process. In addition, FIG. 8 is a diagram illustrating an example of the drive voltage of the first circulating pump 33 and the drive voltage of the second circulating pump 36 if clogging occurs in the internal filter 315. FIG. 9 is a diagram illustrating an example of the drive voltage of the first circulating pump 33 and the drive voltage of the second circulating pump 36 if clogging occurs in the external filter 52.
If the foreign matter of the ink is removed by the external filter 52 and the internal filter 315 by repeatedly executing the circulation of the ink, clogging caused by the foreign matter may occur in the external filter 52 and the internal filter 315. This way, if clogging occurs in the external filter 52 and the internal filter 315, the ink is not supplied to the liquid ejecting head 20 or the supply of the ink is insufficient such that the nozzle surface pressure Pn decreases.
If the nozzle surface pressure Pn decreases in accordance with the control of the nozzle surface pressure by the CPU 71 of the module control unit 38, the CPU 71 increases the output of the first circulating pump 33 as the pressurization pump and decreases the output of the second circulating pump 36 as the depressurization pump in order to increase the nozzle surface pressure Pn. If clogging does not occur in the external filter 52 and the internal filter 315, in accordance with the output control of the first circulating pump 33 and the second circulating pump 36 by the CPU 71, the nozzle surface pressure Pn reaches the set pressure, and subsequently the outputs of the first circulating pump 33 and the second circulating pump 36 are changed by any one of ACT 7, ACT 8, ACT 11, and ACT 12. However, if clogging occurs in the external filter 52 or the internal filter 315, even if the output of the first circulating pump 33 as the pressurization pump increases, and the output of the second circulating pump 36 as the depressurization pump decreases, the nozzle surface pressure Pn does not increase. Therefore, as illustrated in FIGS. 8 and 9, the output of the first circulating pump 33 reaches the adjustment maximum value, and the output of the second circulating pump 36 reaches the adjustment minimum value.
Therefore, the CPU 71 determines that clogging occurs in the external filter 52 and the internal filter 315 based on the output of the first circulating pump 33 and/or the output of the second circulating pump 36.
If the nozzle surface pressure Pn decreases to be lower than the set pressure through the process of FIG. 6, the CPU 71 executes a control such that the nozzle surface pressure Pn increases by increasing the drive voltage of the first circulating pump 33 (ACT 8). Next, if the drive voltage of the first circulating pump 33 reaches the adjustment maximum value (ACT 6, Yes), the CPU 71 executes a control such that the nozzle surface pressure Pn decreases by decreasing the drive voltage of the second circulating pump 36 (ACT 7). Even if the drive voltage of the second circulating pump 36 decreases but the nozzle surface pressure Pn is lower than the set pressure, the CPU 71 decreases the drive voltage of the second circulating pump 36 up to the minimum value (adjustment minimum value) of the drive voltage at which the piezoelectric actuator 59 can operate. For example, if the CPU 71 decreases the output of the second circulating pump 36 up to the adjustment minimum value and the nozzle surface pressure Pn is lower than the set pressure even after a predetermined period of time, the CPU 71 determines that clogging occurs in at least one of the external filter 52 and the internal filter 315.
In a specific example, the CPU 71 determines that clogging occurs in at least one of the external filter 52 and the internal filter 315 by executing the filter clogging determination process illustrated in FIG. 7.
First, in ACT 21, the CPU 71 determines whether or not the output of the second circulating pump 36 as the depressurization pump is the adjustment minimum value. In a specific example, the CPU 71 compares the drive voltage of the second circulating pump 36 and the third threshold to each other, and determines whether or not the second circulating pump 36 is in a range of the drive voltage set to the third threshold. Here, the third threshold has, for example, an upper limit value and a lower limit value similar to the adjustment minimum value of the drive voltage of the second circulating pump 36. For example, the CPU 71 determines whether or not the drive voltage of the second circulating pump 36 is in the range of the third threshold. The reason for this is that, as illustrated in FIGS. 8 and 9, the drive voltage of the second circulating pump 36 at the adjustment minimum value is variable in the predetermined range without exhibiting a given voltage value.
For example, the CPU 71 has a timer function of tracking time, for example, by using a processing circuit or executing a program. If the drive voltage of the second circulating pump 36 is in the range of the third threshold, the CPU 71 starts tracking time as a clogging detection timer for determining filter clogging using the timer function. For example, the CPU 71 uses a predetermined area on the RAM 722 as a timer.
For example, if the CPU 71 determines that the drive voltage of the second circulating pump 36 is not in the range of the third threshold (ACT 21, NO), the CPU 71 resets the clogging detection timer in ACT 22. That is, the CPU 71 sets the value of the area corresponding to the timer on the RAM 722 to 0. In a specific example, in ACT 22, if the CPU 71 determines that the drive voltage of the second circulating pump 36 is not in the range of the third threshold, the CPU 71 resets the clogging detection timer and does not track time. The CPU 71 proceeds to the process of ACT 14.
If the CPU 71 determines that the drive voltage of the second circulating pump 36 is in the range of the third threshold (ACT 21, YES), the CPU 71 increments the clogging detection timer in ACT 23. For example, the CPU 71 increases the value of the predetermined area on the RAM 722 by 1. That is, if the CPU 71 determines that the drive voltage of the second circulating pump 36 is in the range of the third threshold, the CPU 71 starts tracking time and counts an elapsed time since the drive voltage of the second circulating pump 36 is in the range of the third threshold.
The CPU 71 determines whether or not the time tracked by the clogging detection timer in ACT 24 is longer than or equal to a period of time (fourth threshold) for which the filter clogging is determined.
If the CPU 71 determines that the time tracked by the clogging detection timer is shorter than the fourth threshold (ACT 24, NO), the CPU 71 proceeds to the process of ACT 14.
If the CPU 71 determines that the time tracked by the clogging detection timer is longer than or equal to the fourth threshold (ACT 24, YES), the CPU 71 determines that clogging occurs in at least one of the external filter 52 and the internal filter 315 and sets a filter clogging detection flag in ACT 25. In ACT 26, the CPU 71 outputs the circulation end instruction and proceeds to the process of ACT 14.
Based on the filter clogging detection flag, the CPU 71 may transmit the occurrence of clogging in at least one of the external filter 52 and the internal filter 315 to the host control device 13 via the communication interface 73. In addition, if the printer 1 includes a speaker as a notification unit, the CPU 71 may be configured to output a voice representing the occurrence of clogging in at least one of the external filter 52 and the internal filter 315 from the speaker. In addition, if the printer 1 includes a display, the CPU 71 may be configured to cause the display to display the occurrence of clogging in at least one of the external filter 52 and the internal filter 315. In addition, the CPU 71 may be configured to stop printing by stopping the operation of liquid ejecting head drive circuit 77.
The liquid circulating device 30 having the above-described configuration removes foreign matter using the external filter 52 and the internal filter 315 from the ink that is sucked up from the cartridge 51 as the ink replenishment tank and is supplied to the liquid ejecting head 20. The CPU 71 of the liquid circulating device 30 controls the drive voltages of the first circulating pump 33 and the second circulating pump 36 based on the nozzle surface pressure of the liquid ejecting head 20 that is calculated based on the pressure data detected by the pressure sensor 39. In addition, the CPU 71 determines the clogging of the external filter 52 and the internal filter 315 based on the output of the first circulating pump 33 and the output of the second circulating pump 36.
That is, the CPU 71 determines whether or not the ink is circulated due to the clogging of the external filter 52 and the internal filter 315 based on the drive voltage of the first circulating pump 33 and the drive voltage of the second circulating pump 36 that are adjusted based on the nozzle surface pressure. For example, if the drive voltage of the second circulating pump 36 is the adjustment minimum value, the CPU 71 determines the clogging of the external filter 52 and the internal filter 315. This way, the liquid circulating device 30 can detect the clogging in the external filter 52 and the internal filter 315 without adding a configuration for detecting the clogging of the external filter 52 and the internal filter 315 such as a sensor.
In addition, if the period of time for which the drive voltage of the second circulating pump 36 is the adjustment minimum value (third threshold) is longer than or equal to the preset period of time (fourth threshold), the CPU 71 determines that clogging occurs in the external filter 52 and the internal filter 315. The reason for this is as follows. Even in a normal condition where filter clogging does not occur, the output of the depressurization pump (second circulating pump 36) may become instantaneously minimum due to the influence of inflow of bubbles in the circulation flow path 31. However, by determining that clogging occurs in the external filter 52 and the internal filter 315 while the drive voltage of the second circulating pump 36 is maintained at the adjustment minimum value for the predetermined period of time (fourth threshold), the CPU 71 can appropriately determine clogging in the external filter 52 and the internal filter 315.
In the above-described embodiment, the liquid circulating device 30, the liquid ejecting device 10, and the printer 1 can determine clogging in the external filter 52 and the internal filter 315.
In the above-described embodiment, the example where, if the output of the second circulating pump 36 is the third threshold, the CPU 71 determines clogging in the external filter 52 and the internal filter 315 is described. The reason for this is that, if the output of the second circulating pump 36 is the third threshold, the output of the first circulating pump 33 is the first threshold (adjustment maximum value). However, in the filter clogging determination process, the CPU 71 may be configured to further determine that the output of the first circulating pump 33 is the first threshold in addition to the determination that the output of the second circulating pump 36 is the third threshold. In addition, in the above-described embodiment, the example where the state where the output of the second circulating pump 36 is the third threshold continues for the predetermined period of time, the CPU 71 determines that filter clogging occurs is described. However, the CPU 71 may determine that filter clogging occurs if the state where the output of the second circulating pump 36 is the third threshold continues for the predetermined period of time, or if the state where the output of the second circulating pump 36 is the third threshold continues for the predetermined period of time and if a cumulative period of time or a cumulative number of times where the output of the second circulating pump 36 is the third threshold is more than or equal to a predetermined threshold.
In addition, in the above-described embodiment, the example where the first threshold used for the control of the nozzle surface pressure is the adjustment maximum value of the drive voltage of the first circulating pump 33 and the second threshold is the adjustment maximum value of the drive voltage of the second circulating pump 36 is described. However, the embodiment is not limited to this example. For example, the first threshold and the second threshold used for the control of the nozzle surface pressure may be the maximum voltage at which the first circulating pump 33 and the second circulating pump 36 can be driven or may be a voltage value lower than the maximum voltage at which the first circulating pump 33 and the second circulating pump 36 can be driven. Likewise, the example where the third threshold used in the filter clogging determination process is the range of the adjustment minimum value of the second circulating pump 36 is described. However, the embodiment is not limited to this example. For example, the third threshold may be set to be higher than the adjustment minimum value of the second circulating pump 36, and the CPU 71 may determine that filter clogging occurs if the state where the output of the second circulating pump 36 is lower than or equal to the third threshold continues for the fourth threshold or longer.
In addition, in the above-described embodiment, the configuration where the pressure sensor 39 detects the pressure of the air chamber of the buffer tank 35 is described. However, the embodiment is not limited to this configuration. The pressure sensor 39 may be configured to detect each of the pressure of the second flow path 312 and the pressure of the third flow path 313 and to supply the average value thereof to the module control unit 38.
In addition, in the above-described embodiment, the configuration in which the liquid circulating device 30 includes the filter 315 and the liquid ejecting device 10 includes the external filter 52 provided outside the liquid circulating device 30 is described. However, the embodiment is not limited to this configuration.
In addition, the liquid to be ejected is not limited to ink for printing. For example, a device that ejects liquid including conductive particles for forming a wiring pattern of a printed wiring board may also be adopted.
In addition to the above-described structure, the liquid ejecting head may have, for example, a structure where ink droplets are ejected by deforming a diaphragm with static electricity or a structure where ink droplets are ejected from nozzles using thermal energy of a heater or the like.
In addition, in the above-described embodiment, the example where the liquid ejecting head is used for an ink jet recording apparatus or the like is described. However, the embodiment is not limited to this example. For example, the liquid ejecting head can also be used for a 3D printer, an industrial manufacturing machine, or a medical use.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the scope of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope of the inventions.

Claims

A liquid circulating device (30) for a liquid ejecting device (10) which comprises a liquid replenishment tank (51) and a liquid ejecting head (20), the liquid circulating device comprising:
a first pump (33) configured to supply a liquid of the liquid replenishment tank to the liquid ejecting head;

a second pump (36) configured to collect the liquid from the liquid ejecting head and to supply the liquid to the liquid replenishment tank;

a filter provided in a flow path between the liquid replenishment tank and the liquid ejecting head;

a buffer tank (35) that is connected to a flow path between the filter and the liquid ejecting head and a flow path between the liquid ejecting head and the second pump and to which the liquid ejected from the first pump flows in; and

a pressure sensor (39) configured to detect an internal pressure of the buffer tank; and

a control unit configured to determine clogging of the filter based on a drive voltage of the second pump during adjustment circulation where a nozzle surface pressure of the liquid ejecting head is adjusted based on the pressure of the buffer tank.
The device according to claim 1,
wherein if an output of the first pump is higher than or equal to a first threshold and an output of the second pump is lower than or equal to a second threshold, the control unit determines that clogging occurs in the filter.
The device according to claim 2,
wherein if the state where the output of the second pump is lower than or equal to the second threshold continues for a predetermined period of time, the control unit determines that clogging occurs in the filter.
The device according to any one of claims 1 to 3,
wherein the filter is provided in a flow path between the first pump and the liquid ejecting head.
The device according to any one of claims 1 to 4, wherein the filter is provided in a flow path between the liquid replenishment tank and the first circulating pump.
The device according to claim 5, wherein the filter is an external filter provided outside the device.
The device according to any one of claims 1 to 6, wherein the liquid circulating device is provided with the liquid replenishment tank.
A liquid ejecting device (10) comprising:
the liquid circulating device according to claim 1 to 4;

the liquid replenishment tank connected to the first pump;

the liquid ejecting head; and

an external filter provided between the liquid circulating device and the liquid replenishment tank.
A printer (1) including a liquid ejecting device (10) according to claim 8.