Liquid dispensing device, liquid dispensing method, and control device

Abstract

To provide a liquid discharge device which can adjust the density of ink discharged in the time of image formation after maintenance while suppressing a consumption amount of ink in the time of maintenance.SOLUTION: A liquid discharge device 200 comprises: a nozzle part which discharges mixed liquid of first liquid being ink including a color material and auxiliary liquid and second liquid with a higher ratio of the auxiliary liquid than that in the first liquid; a supply part which supplies the mixed liquid to the nozzle part; a control part which controls the respective operations of the supply part and the nozzle part such that the mixed liquid with the higher ratio of the second liquid than that in the mixed liquid in the time of image formation is discharged from the nozzle part in the time of maintenance; and a measurement part which measures the liquid amount of the second liquid used in the time of maintenance. The control part adjusts the density of the color material included in the mixed liquid by supplying the first liquid in the amount according to the liquid amount of the second liquid measured by the measurement part to the nozzle part by the supply part after maintenance.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a liquid ejection device, a liquid ejection method, and a control device.

Background Art

[0002] Conventionally, a liquid ejection device including a liquid container for storing a liquid and a nozzle unit for ejecting the liquid is known. For example, in the liquid ejection devices described in Patent Documents 1 and 2, maintenance is performed to eject the liquid from the nozzle unit in order to maintain or recover the ejection state.

Summary of the Invention

Problems to be Solved by the Invention

[0003] However, in Patent Documents 1 and 2, the consumption amount of the ink may increase by performing maintenance by ejecting the ink from the nozzle unit. In addition, it is required to appropriately adjust the density of the ink ejected at the time of image formation after maintenance.

[0004] An object of the present invention is to provide a liquid ejection device capable of adjusting the density of the ink ejected at the time of image formation after maintenance while suppressing the consumption amount of the ink during maintenance.

Means for Solving the Problems

[0005] A liquid ejection device according to an embodiment includes a nozzle unit that ejects a mixed liquid of a first liquid that is an ink containing a coloring material and an auxiliary liquid, and a second liquid having a higher ratio of the auxiliary liquid than the first liquid, a supply unit that supplies the mixed liquid to the nozzle unit, The supply unit includes a mixing unit that mixes the first liquid and the second liquid to produce a mixed liquid. a control unit that controls each operation of the supply unit and the nozzle unit so as to eject the mixed liquid from the nozzle unit, 1 maintenance operation a measurement unit that measures the amount of the second liquid used during, and the control unit During maintenance, at least one of the following is selected and performed: a first maintenance operation in which the supply unit supplies only the second liquid to the mixing unit and the nozzle unit discharges the mixed liquid from the mixing unit, and a second maintenance operation in which the supply unit supplies both the first and second liquids to the mixing unit and the nozzle unit discharges the mixed liquid from the mixing unit. maintenance operationSubsequently, the supply unit supplies an amount of the first liquid to the nozzle unit corresponding to the amount of the second liquid measured by the measurement unit, thereby adjusting the concentration of the colorant contained in the mixed liquid. [Effects of the Invention]

[0006] According to one embodiment of the liquid dispensing device, the amount of ink consumed during maintenance can be suppressed, while the density of the ink dispensed during image formation after maintenance can be adjusted. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram showing an image forming apparatus according to one embodiment. [Figure 2] This is a schematic diagram showing the ink supply unit. [Figure 3] This is a schematic diagram showing an ink containing colorants and auxiliary liquids. [Figure 4] This is a block diagram showing the hardware configuration of an image forming apparatus according to one embodiment. [Figure 5] This is a block diagram showing a part of the hardware configuration of an image forming apparatus according to one embodiment. [Figure 6] This is a functional block diagram of an image forming apparatus according to one embodiment. [Figure 7] This is a flowchart showing the procedure for maintenance operations. [Figure 8] This is a flowchart showing the procedure for adjusting ink density. [Figure 9] This flowchart shows the procedure for selecting maintenance actions based on the idle time. [Modes for carrying out the invention]

[0008] <Overview of an image forming apparatus> An embodiment of the present invention will be described below with reference to the drawings. In each drawing, arrows indicating the three orthogonal directions, namely the X-axis, Y-axis, and Z-axis, may be shown. The X-axis direction is along the carriage scanning direction. The Y-axis direction is along the transport direction of the recording medium. The Z-axis direction is along the thickness direction of the recording medium PP.

[0009] <Overall configuration of the image forming apparatus 200> Figure 1 is a schematic diagram showing an image forming apparatus according to one embodiment. The image forming apparatus 200 shown in Figure 1 comprises ink supply units 111A to 111D, a recording medium transport mechanism 140, a recording head 10, a carriage 20, and a carriage transport mechanism 150. The image forming apparatus 200 is a serial scanning printer in which an image is formed on the surface of a recording medium PP while the recording head 10 moves in the X-axis direction, which is the main scanning direction. The image forming apparatus 200 is not limited to a serial scanning printer, and may also be a line scanning printer having a line head extending in the X-axis direction. The image forming apparatus 200 is an example of a liquid ejection device. The image forming apparatus 200 can perform a liquid ejection method.

[0010] The recording medium transport mechanism 140 comprises a transport belt 141, transport rollers 142, and tension rollers 143. The transport belt 141 is an endless belt. The transport rollers 142 and tension rollers 143 extend in the X-axis direction and are spaced apart from each other in the Y-axis direction. The transport belt 141 is stretched over the transport rollers 142 and tension rollers 143 and moves in a circular motion as the transport rollers 142 rotate. The transport rollers 142 are driven to rotate by a drive motor. The transport belt 141 transports the recording medium PP in the Y-axis direction.

[0011] The recording head 10 is an inkjet head that ejects liquid ink. The recording head 10 has a pressure chamber for storing ink, a drive element for applying pressure to the ink in the pressure chamber, and a plurality of nozzles for ejecting ink. The recording head 10 is an example of a nozzle section that ejects liquid. The image forming apparatus 200 is equipped with a plurality of recording heads 10 that eject ink of each color: yellow (Y), cyan (C), magenta (M), and black (Bk).

[0012] The driving element generates energy for ejecting ink. The driving element may be a piezoelectric element such as a piezoelectric element. The driving element is not limited to having a piezoelectric element. The driving element may also be an electrothermal conversion element such as a heating resistor, a thermal actuator that utilizes phase change due to film boiling of a liquid, a shape memory alloy actuator that uses metal phase change due to temperature change, or an electrostatic actuator that uses electrostatic force.

[0013] The carriage 20 is equipped with multiple recording heads 10. The multiple recording heads 10 are arranged, for example, in the X-axis direction. The carriage transport mechanism 150 transports the carriage 20 in the X-axis direction. The carriage transport mechanism 150 has guide rods 155 that guide the direction of movement of the carriage 20. The guide rods 155 extend in the X-axis direction above the transport belt 141 that transports the recording medium PP. The carriage transport mechanism 150 includes, for example, a drive motor, gears and belts. Power from the drive motor is transmitted to the carriage 20 via the gears and belts.

[0014] Multiple ink supply units 111A to 111D each supply ink of their respective colors to the recording head 10. The ink supply units 111A to 111D are connected to the recording head 10 via ink supply piping 115.

[0015] Figure 2 is a schematic diagram showing the ink supply unit. As shown in Figure 2, the ink supply unit 111A comprises an ink storage unit 101, an auxiliary liquid storage unit 102, a mixing unit 103, and release valves 104a to 104c. The ink storage unit 101 is a liquid container for storing ink.

[0016] FIG. 3 is a schematic view showing ink containing a coloring material and an auxiliary liquid. The ink includes a coloring material 121 corresponding to each color and an auxiliary liquid 122. The coloring material 121 may be, for example, a dye or a pigment. The auxiliary liquid 122 includes, for example, an auxiliary agent (humectant) having a moisturizing function and an auxiliary agent that can be used to adjust the concentration of the ink. For example, when the manufacturing cost of the ink is 100%, the cost of the coloring material 121 accounts for about 80%, and the cost of the auxiliary liquid 122 accounts for 20%.

[0017] The auxiliary liquid storage portion 102 is a container for storing the auxiliary liquid. The auxiliary liquid storage portion 102 may store only the auxiliary liquid 122. The ink stored in the ink storage portion 101 is an example of a first liquid containing a coloring material and an auxiliary liquid, and the auxiliary liquid stored in the auxiliary liquid storage portion 102 is an example of a second liquid. The ratio of the auxiliary liquid contained in the second liquid is higher than the ratio of the auxiliary liquid contained in the first liquid. The ratio of the auxiliary liquid contained in the second liquid may be 100% or may be 90% or more. There are a first liquid and a second liquid for each type of coloring material.

[0018] The ink storage portion 101 is connected to the mixing portion 103 via a flow path 105a. The auxiliary liquid storage portion 102 is connected to the mixing portion 103 via a flow path 105b. An open valve 104a is provided in the flow path 105a. An open valve 104b is provided in the flow path 105b. The ink supply unit 111A can adjust the flow rate of the ink flowing through the flow path 105a by changing the valve opening degree of the open valve 104a. The ink supply unit 111A can adjust the flow rate of the auxiliary liquid flowing through the flow path 105b by changing the valve opening degree of the open valve 104b.

[0019] The mixing unit 103 has a container for storing liquid. It mixes the ink supplied from the ink storage unit 101 and the auxiliary liquid supplied from the auxiliary liquid storage unit 102. The mixing unit 103 is connected to the recording head 10 via the ink supply pipe 115. The ink and auxiliary liquid in the mixing unit 103 flow through the ink supply pipe 115 and are supplied to the recording head 10. The liquid in the mixing unit 103 may be only the ink supplied from the ink storage unit 101, only the auxiliary liquid supplied from the auxiliary liquid storage unit 102, or a mixture of these inks and auxiliary liquids.

[0020] The ink storage unit 101 may be a cartridge filled with ink. The auxiliary fluid storage unit 102 may be a cartridge filled with auxiliary fluid. The ink storage unit 101 may be a tank type, for example. A liquid container with a larger capacity than the ink storage unit 101 may be connected to the ink storage unit 101. This allows ink to be replenished from the large-capacity liquid container to the ink storage unit 101. Similarly, the auxiliary fluid storage unit 102 may also be a tank type. The ink supply units 111A to 111D may have an auxiliary fluid storage unit 102 common to multiple ink supply units 111A to 111D. The auxiliary fluid storage unit 102 may supply auxiliary fluid to the mixing unit 103 of the multiple ink supply units 111A to 111D.

[0021] Since the ink supply units 111B to 111D have the same configuration as ink supply unit 111A, the explanation of ink supply units 111B to 111D will be omitted.

[0022] <Hardware configuration of image forming apparatus> Next, the hardware configuration of the image forming apparatus 200 will be described with reference to Figure 4. Figure 4 is a block diagram showing the hardware configuration of an image forming apparatus according to one embodiment. The hardware configuration shown in Figure 4 may include additional components as needed. The hardware may not include the components shown in Figure 4 as needed.

[0023] The image forming apparatus 200 is equipped with a control device 500. The control device 500 has a CPU (Center Processing Unit) 501, a ROM (Read Only Memory) 502, a RAM (Random Access Memory) 503, and an NVRAM (Random Access Memory) 504. The CPU 501 controls the entire image forming apparatus 200. The ROM 502 stores various programs for the CPU 501 to execute liquid dispensing control.

[0024] RAM 503 temporarily stores various data. NVRAM 504 is a non-volatile memory that can retain data even when the power supply to the image forming apparatus 200 is cut off.

[0025] The control device 500 includes an ASIC (Application Specific Integrated Circuit) 505. The ASIC 505 processes input and output signals for controlling the overall operation of the image forming apparatus 200. The ASIC 505 can also perform various signal processing operations on image data. The ASIC 505 can perform image processing on image data input to the control device 500.

[0026] The control device 500 is equipped with a host interface (host I / F) 506 that enables it to send and receive data with an external device, the host 600. The host 600 includes an information processing device such as a personal computer, an image reading device such as an image scanner, and an imaging device such as a digital camera. The control device 500 receives data transmitted from the host 600.

[0027] The CPU 501 of the control device 500 reads and analyzes the print data in the receive buffer included in the I / F 506. The ASIC 505 performs necessary image processing and data rearrangement. The host 600 has a printer driver 601. The printer driver 601 generates dot pattern data for image output from the image forming apparatus 200.

[0028] Furthermore, the control device 500 includes an I / O unit (input / output unit) 507 for receiving detection signals output from the sensor group 18.

[0029] The sensor group 18 may include an optical sensor for detecting the position of the recording medium PP. The sensor group 18 may include various temperature sensors. The sensor group 18 may include a thermistor for detecting the temperature and humidity inside the image forming apparatus 200. The sensor group 18 may include a sensor for detecting the voltage of the charging belt. The sensor group 18 may include an interlock switch for detecting the opening and closing of a cover which is part of the housing of the image forming apparatus 200.

[0030] The sensor group 18 includes a sensor for detecting the liquid level in the ink storage section 101. The sensor group 18 includes a sensor for detecting the liquid level in the auxiliary liquid storage section 102. The sensor group 18 may also include a full-tank detection sensor for detecting the displacement member of the sub-tank. The sensor group 18 may include a detection electrode pin for detecting the liquid level. The sensor group 18 may also include a pressure sensor and a flow meter, etc. The sub-tank may include the ink storage section 101, the auxiliary liquid storage section 102 and the mixing section 103. The sensor group 18 includes a sensor for detecting the amount of ink consumed. The sensor group 18 includes a sensor for detecting the amount of auxiliary liquid consumed.

[0031] The I / O unit 507 acquires information from various sensor groups 18 and extracts information necessary for controlling the printer. The I / O unit 507 can process the various information acquired from the sensor groups 18.

[0032] The control device 500 includes a head control device 510 that controls the drive of the recording head 10. The head control device 510 can control the operation of a head driver 12 for driving the recording head 10. The head driver 12 is mounted on the carriage 20 and is electrically connected to the recording head 10. The head driver is also called a driver IC. The head control device 510 can control the drive elements of the recording head 10 to perform liquid ejection. The head control device 510 can perform various controls related to the recording head 10.

[0033] The head control device 510 includes a drive signal generation unit that generates drive signals for controlling the drive of the recording head 10, and a data transfer unit that transfers the drive signals to the head driver 12.

[0034] The control device 500 transfers the processed image data from the head control device 510 to the head driver 12.

[0035] The head control device 510 can transfer the image data described above as serial data. The head control device 510 may also transfer a transfer clock signal necessary for transferring and confirming the transfer of image data to the head driver 509. The head control device 510 can output latch signals and control signals to the head driver 509 for controlling ink ejection.

[0036] The drive signal generation unit of the head control device 510 includes a D / A converter, a voltage amplifier, and a current amplifier. The D / A converter can perform D / A conversion on drive pulse pattern data stored in, for example, the ROM 502. The drive pulse is included in the drive signal. The voltage amplifier can amplify, for example, the voltage based on the drive pulse. The current amplifier may amplify the current based on the drive pulse. The drive signal generation unit outputs a drive signal consisting of one or more drive pulses to the head driver 12.

[0037] The head driver 12 supplies a voltage based on a drive pulse to a piezoelectric element to eject ink from the recording head 10. The head control device 510 can select drive pulses to print dots of different sizes, such as large, medium, and small droplets.

[0038] The image forming apparatus 200 includes a main scanning motor 151, a sub-scanning motor 152, and a maintenance / recovery motor 154. The control device 500 includes a motor drive device 511. The motor drive device 511 controls the driving of the main scanning motor 151, the sub-scanning motor 152, and the maintenance / recovery motor 154. The motor drive device 511 controls the driving of the main scanning motor 151, the sub-scanning motor 152, and the maintenance / recovery motor 154 according to commands from the CPU 501.

[0039] The main scanning motor 151 is a motor for driving the carriage 20. The sub-scanning motor 152 is a motor for moving the conveyor belt 141 in a circular motion. The maintenance and recovery motor 153 is a motor for driving the maintenance and recovery mechanism 81.

[0040] The image forming apparatus 200 is equipped with a charging roller 56. The control device 500 is equipped with an AC bias supply device 512. The AC bias supply device 512 supplies AC bias to the charging roller 56 according to a command from the CPU 501. The charging roller 56 can charge the transport belt 141 when transporting the recording medium PP. This allows the recording medium PP to be attracted to the transport belt 141.

[0041] The image forming apparatus 200 includes a sub-tank 35. The sub-tank 35 is provided with an atmospheric release mechanism 36 for releasing the pressure inside the tank to the atmosphere. The image forming apparatus 200 includes an atmospheric release solenoid 37 for driving the atmospheric release mechanism 36. The control device 500 includes a solenoid drive device 513 for controlling the driving of the atmospheric release solenoid 37.

[0042] The image forming apparatus 200 includes a liquid transfer pump 39. The liquid transfer pump 39 is connected to the ink supply units 111A to 111D. The liquid transfer pump 39 transfers ink to the recording head 10. The control device 500 includes a pump drive device 514 that controls the drive of the liquid transfer pump 39. The pump drive device 514 controls the drive of the liquid transfer pump 39 according to commands from the CPU 501.

[0043] The image forming apparatus 200 may include an operation panel 516. The operation panel 516 is electrically connected to the control device 500. The operation panel 516 includes a display unit for displaying various information. The user can perform input operations using the operation panel 516. The control device 500 receives information from the operation panel 516 based on the user's operation input. The control device 500 can output various signals to the operation panel 516 and display information on the operation panel 516. The user may perform input operations while referring to the information displayed on the operation panel 516. The operation panel 516 is an example of an operation input unit.

[0044] <Maintenance Department> Next, the maintenance unit 60 will be described with reference to Figure 5. Figure 5 is a block diagram showing a part of the hardware configuration of an image forming apparatus according to one embodiment. The hardware configuration shown in Figure 5 is a part of the hardware configuration shown in Figure 4. The hardware configuration shown in Figure 5 may include additional components as needed. The hardware may not have to include the components shown in Figure 5 as needed.

[0045] The image forming apparatus 200 performs maintenance operations to suppress clogging of the recording head 10, non-discharge, discharge deviation, changes in discharge speed, and changes in discharge volume due to ink viscosity, and to maintain or restore the discharge state.

[0046] The image forming apparatus 200 includes a maintenance unit 60 that performs maintenance on the recording head 10. The maintenance unit 60 performs maintenance operations by ejecting liquid from the nozzles of the recording head 10. In this case, the maintenance unit 60 includes ink supply units 111A to 111D, the recording head 10, and the head driver 12. The maintenance unit 60 can perform maintenance operations by discharging liquid that does not contribute to image formation from the nozzles of the recording head 10. Maintenance operations include, for example, flushing, dry ejection, and purging.

[0047] The maintenance unit 60 includes a first maintenance unit 61 and a second maintenance unit 62. The first maintenance unit 61 can perform a first maintenance operation. The first maintenance operation includes supplying only the auxiliary liquid in the auxiliary liquid storage unit 102 to the mixing unit 103, supplying the liquid in the mixing unit 103 to the recording head 10, and discharging the auxiliary liquid from the nozzle of the recording head 10. The first maintenance unit 61 may include, for example, the auxiliary liquid storage unit 102, the release valves 104b, 104c, the mixing unit 103, and the ink supply piping 115.

[0048] The second maintenance unit 62 can perform a second maintenance operation different from the first maintenance operation. The second maintenance operation includes discharging liquid from the nozzle of the recording head 10 using a liquid containing a colorant of a different concentration than the liquid used in the first maintenance operation. In this case, the second maintenance unit 62 may include, for example, an ink storage unit 101, release valves 104a, 104b, a mixing unit 103, and an ink supply pipe 115.

[0049] The second maintenance operation may be other maintenance operations, such as wiping. The second maintenance unit 62 may include, for example, a wiper that contacts the nozzle surface of the recording head 10. The second maintenance unit 62 may also include a motor, pump, and power transmission mechanism necessary for the second maintenance operation.

[0050] The control device 500 includes a maintenance control device 520 that controls the maintenance operations performed by the maintenance unit 60. The maintenance control device 520 functions as a first maintenance control unit that controls the first maintenance operations performed by the first maintenance unit 61 in accordance with commands from the CPU 501. The maintenance control device 520 also functions as a second maintenance control unit that controls the second maintenance operations performed by the second maintenance unit 62 in accordance with commands from the CPU 501.

[0051] The image forming apparatus 200 is equipped with a solenoid 63 for adjusting the valve opening degree of the opening valves 104a to 104c. The control device 500 has a solenoid drive unit 522 that controls the driving of the solenoids 63a to 63c. By controlling the driving of the solenoids 63a to 63c, the control device 500 can change the valve opening degree of the opening valves 104a to 104c and change the amount of ink and auxiliary liquid supplied to the mixing unit 103. As a result, the control device 500 can change the concentration of the auxiliary liquid and the colorant in the liquid in the mixing unit 103.

[0052] The control device 500 can supply only the auxiliary liquid in the auxiliary liquid storage section 102 to the mixing section 103 by closing the release valve 104a and opening the release valve 104b. The control device 500 can then supply only the auxiliary liquid in the mixing section 103 to the recording head 10 and have it discharged from the nozzle. As a result, the image forming apparatus 200 can perform maintenance on the nozzle of the recording head 10 using only the auxiliary liquid.

[0053] The control device 500 can supply only the ink in the ink storage section 101 to the mixing section 103 by opening the release valve 104a and closing the release valve 104b. The control device 500 may also supply only the ink in the mixing section 103 to the recording head 10 and have it ejected from the nozzle. This allows the image forming apparatus 200 to perform maintenance on the nozzles of the recording head 10 using only ink.

[0054] The control device 500 can change the concentration of the colorant in the mixed liquid within the mixing unit 103 by supplying only ink to the mixing unit 103 after performing maintenance on the nozzles of the recording head 10 using only the auxiliary liquid. The solenoids 63a to 63c and the release valves 104a to 104c are an example of a concentration adjustment unit that can adjust the concentration of the colorant in the mixed liquid.

[0055] The control device 500 may, for example, set the valve opening of the opening valve 104b to be greater than the valve opening of the opening valve 104a. The control device 500 can change the concentration of the colorant and auxiliary liquid contained in the mixed liquid in the mixing unit 103 by changing the valve openings of the opening valves 104a and 104b. The image liquid device 100 may, for example, perform maintenance on the recording head 10 using a mixed liquid with a low concentration of colorant. This can reduce ink consumption during maintenance.

[0056] The control device 500 can change the concentration of the colorant in the mixed liquid of the mixing unit 103 based on information entered by the user using the operation panel 516. The control device 500 can select at least one of the first maintenance operation and the second maintenance operation and perform the maintenance operation based on information entered by the user using the operation panel 516.

[0057] The control device 500 can select at least one of a first maintenance operation and a second maintenance operation and perform the maintenance operation depending on the length of time that ink has not been ejected from the recording head 10. For example, the control device 500 may perform the second maintenance operation when the waiting time is short and the first maintenance operation when the waiting time is long. For example, the control device 500 may perform a maintenance operation using ink when the waiting time is short and the first maintenance operation using only auxiliary fluid when the waiting time is long.

[0058] <Functional Configuration> Next, the functional configuration of the image forming apparatus 200 will be described with reference to Figure 5. Figure 5 is a functional block diagram of the image forming apparatus 200. The CPU 501 shown in Figure 4 executes programs stored in a storage unit such as the ROM 502 to realize the functions of the system control unit 321, memory control unit 322, communication control unit 323, discharge control unit 324, transport control unit 325, maintenance control unit 330, liquid consumption measurement unit 341, pressure detection unit 342, calculation unit 343, and determination unit 344 shown in Figure 5. External devices and sensors connected to the control device 500 may perform some of these functions.

[0059] The system control unit 321 controls the overall operation of the image forming apparatus 200. The memory control unit 322 controls the operation of the memory such as ROM 502, RAM 503, and NVRAM 504. The communication control unit 323 controls communication with external devices connected to the control device 500.

[0060] The ejection control unit 324 controls the ejection of liquid by the recording head 10. During image formation, the ejection control unit 324 controls the operation of the ink supply units 111A to 111D to supply the ink in the ink storage unit 101 and the auxiliary liquid in the auxiliary liquid storage unit 102 to the mixing unit 103 to generate a mixed liquid. During image formation, the ejection control unit 324 controls the operation of the ink supply units 111A to 111D and the recording head 10 to supply the mixed liquid in the mixing unit 103 to the recording head 10 and eject the mixed liquid from the recording head 10. The transport control unit 325 controls the transport of the recording medium PP by the transport unit. The transport unit includes rollers for transporting the recording medium PP and a motor for driving the rollers.

[0061] The maintenance control unit 330 controls the first maintenance operation and the second maintenance operation. When the first maintenance operation is performed, the maintenance control unit 330 may control the ink supply units 111A to 111D and the recording head 10 so that only auxiliary liquid is supplied from the ink supply units 111A to 111D to the recording head 10 and the auxiliary liquid is discharged from the recording head 10. When the second maintenance operation is performed, the maintenance control unit 330 may control the ink supply units 111A to 111D and the recording head 10 so that a mixture of ink and auxiliary liquid is supplied from the ink supply units 111A to 111D to the recording head 10 and the mixture is discharged from the recording head 10. The liquid consumption measurement unit 341 can measure the amount of ink consumed. The liquid consumption measurement unit 341 may calculate the amount of ink consumed based on the amount of ink discharged from the recording head 10. The liquid consumption measurement unit 34 can determine the number of ink drops and the appropriate amount of ink based on information output from, for example, the dispensing control unit 324, and measure the amount of ink consumed. The liquid consumption measurement unit 341 can calculate the amount of ink consumed based on the remaining amount of ink in the ink storage unit 101.

[0062] The liquid consumption measurement unit 341 can, for example, measure the amount of auxiliary fluid consumed during the first maintenance operation. Based on the information output from the maintenance control unit 330, the liquid consumption measurement unit 341 can measure the amount of auxiliary fluid consumed during the first maintenance operation. The amount of auxiliary fluid consumed here refers to the amount of auxiliary fluid consumed in the auxiliary fluid storage unit 102 and does not include the auxiliary fluid contained in the ink. The liquid consumption measurement unit 341 may also calculate the amount of auxiliary fluid consumed during the first maintenance operation based on the remaining amount of auxiliary fluid in the auxiliary fluid storage unit 102. The liquid consumption measurement unit 341 is an example of a measurement unit that measures the amount of auxiliary fluid, which is the second liquid used when the first maintenance operation is performed.

[0063] The pressure detection unit 342 detects the pressure in the sub-tank 35 by detecting a displacement member based on the detection signal from the full tank detection sensor. The sub-tank 35 may be referred to as a head tank or fan tank. The mixing unit may be located between the back of the ink cartridge and the sub-tank 35. The sub-tank 35, full tank detection sensor, and displacement member are well-known technologies. The displacement member can be displaced according to the pressure in the sub-tank 35 and the amount of ink remaining in the sub-tank 35. As a result, the amount of ink remaining may be detected based on the displacement of the displacement member.

[0064] The calculation unit 343 calculates the amount of ink to be supplied to the mixing unit 103 during printing, according to the amount of auxiliary liquid consumed measured by the liquid consumption measurement unit 341. Here, "during printing" includes, for example, printing after the first maintenance operation using the auxiliary liquid has been performed.

[0065] The calculation unit 343 may also calculate the maximum usable ink amount in the sub-tank 35. The maximum usable ink amount may be used when performing emergency printing to deplete the sub-tank.

[0066] The determination unit 344 performs various determinations in the control device 500. The determination unit 344 may determine whether or not to perform a first maintenance operation. The determination unit 344 may determine whether or not to perform a second maintenance operation. The determination unit 344 can perform various determinations related to maintenance operations. When performing multiple maintenance operations, the determination unit 344 may determine the order in which the maintenance operations will be performed.

[0067] The determination unit 344 determines, for example, whether or not to perform control to create negative pressure in the sub-tank 35 based on the maximum usable ink amount, which is the result of calculation by the calculation unit 343. For example, the determination unit 344 can make the above determination when performing emergency printing to deplete the sub-tank.

[0068] Furthermore, the system control unit 321, memory control unit 322, communication control unit 323, discharge control unit 324, transport control unit 325, maintenance control unit 330, liquid consumption measurement unit 341, pressure detection unit 342, calculation unit 343, and determination unit 344 can be implemented in software by programs stored in the storage unit 508. However, all or part of these system control unit 321, memory control unit 322, communication control unit 323, discharge control unit 324, transport control unit 325, maintenance control unit 330, liquid consumption measurement unit 341, pressure detection unit 342, calculation unit 343, and determination unit 344 may be implemented in hardware such as an IC (Integrated Circuit).

[0069] Furthermore, the program may be recorded as installable or executable file information on a recording medium readable by a computer device, such as a CD-ROM or flexible disk (FD), and provided to the image forming apparatus 200 via such a recording medium. Alternatively, the program may be recorded on a recording medium readable by a computer device, such as a CD-R, DVD (Digital Versatile Disk), Blu-ray® disc, or semiconductor memory, and provided to the image forming apparatus 200 via such a recording medium. The program may also be provided to the image forming apparatus 200 by installation via a network such as the Internet. Furthermore, the program may be pre-installed in ROM or the like within the image forming apparatus 200.

[0070] Furthermore, the control device 500 may perform functions that are executed by a computer connected to the control device 500. Similarly, a computer connected to the control device 500 may perform functions that are executed by the control device 500.

[0071] <Operation of the image forming apparatus> Next, the operation of the image forming apparatus 200 will be described with reference to Figure 7. Figure 7 is a flowchart showing the procedure in maintenance operation. First, the determination unit 344 of the control device 500 determines whether or not to perform the first maintenance operation. The determination unit 344 determines whether or not to perform the first maintenance operation depending, for example, on the usage status of the image forming apparatus 200.

[0072] The determination unit 344 can determine, for example, whether to perform the first maintenance operation when the number of printed pages exceeds a predetermined threshold. The determination unit 344 can also determine whether to perform the first maintenance operation based on the remaining amount of ink in the ink storage unit 101. The determination unit 344 may also determine whether to perform the first maintenance operation based on user input.

[0073] If the CPU 501 of the control device 500 determines to perform the first maintenance operation (step S11; YES), it proceeds to step S12; otherwise, it determines not to perform the first maintenance operation (step S11; NO), it proceeds to step S13.

[0074] In step S12, the control device 500 controls the operation of the first maintenance unit 61 so that only the auxiliary liquid stored in the auxiliary liquid storage unit 102 is supplied to the mixing unit 103, and the first maintenance operation can be performed using only the auxiliary liquid. The control device 500 opens and closes the release valves 104a and 104b so that only the auxiliary liquid in the auxiliary liquid storage unit 102 is supplied to the mixing unit 103.

[0075] In step S13, the control device 500 controls the second maintenance unit 62 so that it can perform the second maintenance operation using a mixture of ink and auxiliary liquid, by supplying both the ink stored in the ink storage unit 101 and the auxiliary liquid stored in the auxiliary liquid storage unit 102 to the mixing unit 103. The control device 500 opens and closes the release valves 104a and 104b so that both the ink and auxiliary liquid are supplied to the mixing unit 103.

[0076] After executing steps S12 and S13, the control device 500 proceeds to step S14, where it controls the maintenance unit 60 to perform various maintenance operations. The control device 500 performs the maintenance operation by supplying the liquid in the mixing unit 103 to the recording head 10 and discharging the liquid from the nozzle.

[0077] The first maintenance unit 61 can perform the first maintenance operation by discharging only the auxiliary liquid from the mixing unit 103 through the nozzle. The second maintenance unit 62 can perform the second maintenance operation by discharging the mixed liquid from the mixing unit 103 through the nozzle. The second maintenance unit 62 may also perform other maintenance operations as the second maintenance operation.

[0078] Next, the operation of the image forming apparatus 200 will be described with reference to Figure 8. Figure 8 is a flowchart showing the procedure in the operation of adjusting the ink density. First, the determination unit 344 of the control device 500 determines whether or not the first maintenance operation has been completed (step S21). The determination unit 344 can determine whether or not the first maintenance operation has been completed based on information output from the maintenance control unit 330, for example. If the control device 500 determines that the first maintenance operation has been completed (step S21; YES), it proceeds to step S22. If the control device 500 determines that the first maintenance operation has been completed (step S21; NO), it periodically executes step S21 until the first maintenance operation is completed.

[0079] In step S22, the liquid consumption measuring unit 341 of the control device 500 measures the amount of auxiliary fluid consumed during the first maintenance operation. The liquid consumption measuring unit 341 measures the amount of auxiliary fluid consumed during the first maintenance operation based on the information output from the maintenance control unit 330.

[0080] Next, the calculation unit 343 of the control device 500 calculates the amount of ink to be supplied to the mixing unit 103 according to the amount of auxiliary liquid consumed measured by the liquid consumption measurement unit 341. The storage unit 508 may store data showing the relationship between the amount of auxiliary liquid consumed and the amount of ink supplied. For example, if the amount of auxiliary liquid consumed is large, the concentration of colorant in the liquid remaining in the mixing unit 103, the ink supply pipe 115, and the recording head 10 is lower than the concentration of colorant in the ink. Also, if the amount of auxiliary liquid consumed is large, the concentration of colorant in the liquid remaining in the recording head 10 is lower compared to when the amount of auxiliary liquid consumed is small.

[0081] The calculation unit 343 increases the ink supply amount when the auxiliary fluid consumption is high, compared to when the auxiliary fluid consumption is low.

[0082] Next, the maintenance control unit 330 of the control device 500 controls the operation of the ink supply units 111A to 111D to adjust the concentration of ink supplied to the recording head 10. The maintenance control unit 330 supplies the amount of ink calculated in step S23 to the mixing unit 103 by controlling the valve opening of the release valves 104a to 104c. The control device 500 can adjust the concentration of the colorant in the ink supplied to the recording head 10 by adjusting the ink concentration of the liquid in the mixing unit 103. After executing step S24, the control device 500 terminates this process.

[0083] Next, with reference to Figure 9, the process for selecting maintenance operations according to the idle time will be explained. Figure 9 is a flowchart showing the procedure for selecting maintenance operations according to the idle time. First, the determination unit 344 of the control device 500 determines whether or not to perform a maintenance operation (step S31). The determination unit 344 determines to perform a maintenance operation if predetermined conditions are met. For example, the determination unit 344 may determine to perform a maintenance operation on the condition that the power to the image forming apparatus 200 has been turned on. Alternatively, the determination unit 344 may determine to perform a maintenance operation on the condition that a certain amount of time has elapsed after the power has been turned on.

[0084] Furthermore, the determination unit 344 may determine whether or not to perform a maintenance operation based on the length of time that has passed since the liquid was ejected by the recording head 10 and no liquid has been ejected. The determination unit 344 may also determine whether or not to perform a maintenance operation based on the number of printed pages. Furthermore, the determination unit 344 may also determine whether or not to perform a maintenance operation based on user input. If the control device 500 determines to perform a maintenance operation (step S31: YES), it proceeds to step S32, and if it determines not to perform a maintenance operation (step S31: NO), it repeats step S31 and waits for a predetermined condition to be met.

[0085] In step S32, the determination unit 344 determines whether the standing time exceeds the determination threshold. The standing time is the length of time after liquid is dispensed by the recording head 10 but no liquid is being dispensed. If the standing time exceeds the determination threshold (step S32; YES), the control device 500 proceeds to step S12, and if the standing time does not exceed the determination threshold (step S32; NO), it proceeds to step S13.

[0086] As described above, in step S12, the image forming apparatus 200 supplies only the auxiliary liquid to the recording head 10, as described above, and proceeds to step S14 to perform the first maintenance operation. In step S13, the image forming apparatus 200 supplies ink and the auxiliary liquid to the mixing unit 103 to produce a mixed liquid, supplies the mixed liquid to the recording head 10, and proceeds to step S14 to perform the second maintenance operation.

[0087] The control device 500 selects and executes the first maintenance operation if the idle time exceeds the determination threshold. The control device 500 selects and executes the second maintenance operation if the idle time does not exceed the determination threshold.

[0088] <Effects and Effects of Image Forming Apparatus> With this image forming apparatus 200, the first maintenance operation can be performed using only the auxiliary fluid in the auxiliary fluid storage section 102. This allows the maintenance operation of the recording head 10 to be performed while reducing ink consumption. As a result, the image forming apparatus 200 can reduce ink consumption during maintenance.

[0089] The image forming apparatus 200 can adjust the concentration of the colorant in the mixed liquid within the mixing unit 103 by measuring the amount of auxiliary liquid consumed after performing the first maintenance operation and changing the amount of ink supplied to the mixing unit 103 according to the amount of auxiliary liquid consumed. This allows the image forming apparatus 200 to adjust the concentration of the colorant in the mixed liquid supplied to the recording head 10 after the first maintenance operation using only the auxiliary liquid. Therefore, the image forming apparatus 200 can adjust the concentration of the colorant in the droplets ejected from the recording head 10 after performing the first maintenance operation. In the image forming apparatus 200, the concentration of the colorant in the recording head 10 fluctuates when the first maintenance operation is performed, but the concentration of the colorant can be adjusted according to the amount of auxiliary liquid consumed. According to the image forming apparatus 200, the amount of colorant consumed during maintenance can be suppressed while adjusting the concentration of the ink ejected during image formation after maintenance.

[0090] Furthermore, if the image forming apparatus 200 performs the first maintenance operation multiple times, it may adjust the density of the colorant after each first maintenance operation, or it may adjust the density of the colorant all at once for multiple operations.

[0091] The image forming apparatus 200 is equipped with an operation panel 516 that can be operated by the user, and the control device 500 controls the operation of the opening valves 104a to 104c based on the user's operation on the operation panel 516, thereby changing the concentration of the colorant contained in the mixed liquid in the mixing unit 103.

[0092] With this configuration of the image forming apparatus 200, the user can change the concentration of the colorant in the mixed solution supplied to the recording head 10 using the operation panel 516. For example, if the user is not concerned with image quality, they can change the concentration of the colorant by increasing the amount of auxiliary liquid supplied from the auxiliary liquid storage unit 102 to reduce ink consumption. For example, if the user desires improved image quality, they can increase the ink consumption to increase the concentration of the colorant.

[0093] Furthermore, in the image forming apparatus 200, the control device 500 can select at least one of a first maintenance operation and a second maintenance operation depending on the length of time the recording head 10 is not in use. The control device 500 can also change the density of the colorant supplied to the recording head 10 during maintenance depending on the length of time it is in use.

[0094] For example, if the image forming apparatus 200 is left unused for a long period of time, the ink remaining in the recording head 10 will become thicker. When the ink becomes thicker in this way, the flow rate of the maintenance liquid flowing through the recording head 10 increases compared to when the ink is not thickened. The image forming apparatus 200 can suppress ink consumption during maintenance by performing a first maintenance operation in which only auxiliary liquid is supplied to the recording head 10 when the period of inactivity is long.

[0095] On the other hand, when the printing operation in the image forming apparatus 200 is performed frequently, performing the first maintenance operation using only the auxiliary liquid results in a longer downtime compared to performing the second maintenance operation using ink. This is because, after the first maintenance operation, it is necessary to adjust the concentration of the colorant contained in the mixed liquid in the mixing unit 103, which increases the downtime. If the maintenance operation is performed using a liquid with a lower concentration than the ink concentration used during printing, it becomes necessary to adjust the concentration of the colorant afterward, which also increases the downtime. In the image forming apparatus 200, the increase in downtime can be suppressed by allowing at least one of the first and second maintenance operations to be selected according to the frequency of use.

[0096] Furthermore, in the image forming apparatus 200, the control device 500 can select at least one of the first maintenance operation and the second maintenance operation based on user operation on the operation panel 516.

[0097] With this configuration of the image forming apparatus 200, the user can change the selection by operating the control panel 516 so that at least one of the first maintenance operation and the second maintenance operation is performed. If the user wants to reduce ink consumption during maintenance, they can operate the control panel 516 to set the execution of the first maintenance operation. If the user wants to reduce downtime even if it means accepting increased ink consumption, they can also select a maintenance operation different from the pre-set automatic control. In this way, the image forming apparatus 200 can perform maintenance operations according to the user's preferences, thereby improving user convenience.

[0098] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from or altering the technical concept of the present invention.

[0099] In the above embodiment, the first maintenance operation is illustrated as a case in which the recording head 10 is maintained using only the auxiliary liquid, but the first maintenance operation is not limited to the case in which only the auxiliary liquid is used for maintenance. The second liquid used in the first maintenance operation may contain, for example, a colorant. The second liquid used in the first maintenance operation only needs to have a higher concentration of the auxiliary liquid than the first liquid, which is the ink. The concentration of the colorant in the second liquid is lower than the concentration of the colorant in the first liquid.

[0100] In the above embodiment, the first maintenance operation is illustrated as the discharge of liquid from the nozzle of the recording head 10, but the first maintenance operation is not limited to this. For example, the first maintenance operation may include supplying a second liquid to the recording head 10 and circulating the liquid within the recording head 10.

[0101] In the above embodiment, the second maintenance operation is illustrated as one in which maintenance of the recording head 10 is performed using the ink in the ink storage unit 101, but the second maintenance operation is not limited to this. For example, the image forming apparatus 200 may perform the second maintenance by supplying a mixture of ink and auxiliary liquid, obtained by mixing in the mixing unit 103, to the recording head 10.

[0102] Furthermore, the image forming apparatus 200 may perform multiple types of maintenance operations as a first maintenance operation. The image forming apparatus 200 may also perform multiple types of maintenance operations as a second maintenance operation. The second maintenance operation is a maintenance operation performed in a manner different from the first maintenance operation, and includes maintenance operations for ensuring stable liquid discharge at the nozzle. [Explanation of symbols]

[0103] 200 Image forming device (liquid ejection device) 10. Recording head (nozzle section) 60 Maintenance Department 61. First Maintenance Department 62 Second Maintenance Department 101 Ink storage section 102 Auxiliary fluid storage section 103 Mixing section 111A~111D Supply section 121 Colorants 122 Auxiliary fluid 330 Maintenance Control Unit 341 Liquid consumption measuring section 342 Pressure detection unit 343 Calculation Unit 344 Judgment section 500 Control device (control unit) 510 Head control device 513 Solenoid drive unit 514 Pump drive unit 516 Control Panel (Input Section) 520 Maintenance control device (first maintenance control unit, second maintenance control unit) PP recording medium [Prior art documents] [Patent Documents]

[0104] [Patent Document 1] Japanese Patent Publication No. 2013-119190 [Patent Document 2] Japanese Patent Publication No. 2008-904

Claims

1. A nozzle unit that dispenses a mixture of a first liquid, which is an ink containing a colorant and an auxiliary liquid, and a second liquid, which has a higher ratio of auxiliary liquid than the first liquid, A supply unit that supplies the aforementioned mixture to the nozzle section, The supply unit includes a mixing unit that mixes the first liquid and the second liquid to produce the mixed liquid, A control unit that controls the operation of the supply unit and the nozzle unit so that the mixed liquid is discharged from the nozzle unit, The system includes a measuring unit for measuring the amount of the second liquid used during the first maintenance operation, The control unit, During maintenance, at least one of the following is selected and performed: a first maintenance operation in which the supply unit supplies only the second liquid to the mixing unit and the nozzle unit discharges the mixed liquid from the mixing unit; and a second maintenance operation in which the supply unit supplies both the first liquid and the second liquid to the mixing unit and the nozzle unit discharges the mixed liquid from the mixing unit. A liquid dispensing device characterized by adjusting the concentration of the colorant contained in the mixed liquid by supplying the nozzle unit with an amount of the first liquid corresponding to the amount of the second liquid measured by the measuring unit after the first maintenance operation.

2. The measuring unit measures the amount of the second liquid used during the second maintenance operation, The liquid dispensing device according to claim 1, characterized in that the control unit adjusts the concentration of the colorant contained in the mixed liquid by supplying the nozzle unit with an amount of the first liquid corresponding to the amount of the second liquid measured by the measuring unit after the second maintenance operation.

3. It further includes an operation input section that can be operated by the user, The liquid dispensing device according to claim 1 or 2, characterized in that the control unit can change the concentration of the colorant contained in the mixed liquid by controlling the operation of the supply unit based on the operation of the operation input unit.

4. The liquid dispensing device according to claim 1, characterized in that the control unit selects at least one of the first maintenance operation and the second maintenance operation according to the length of time that has been left without dispensing liquid from the nozzle.

5. It further includes an operation input section that can be operated by the user, The liquid dispensing apparatus according to claim 1, characterized in that the control unit selects at least one of the first maintenance operation and the second maintenance operation based on the operation of the operation input unit.

6. A liquid dispensing method comprising generating a mixture of a first liquid, which is an ink containing a colorant and an auxiliary liquid, and a second liquid having a higher ratio of auxiliary liquid than the first liquid, in a mixing unit and dispensing the mixture from a nozzle unit, During maintenance, at least one of the following is selected and performed: a first maintenance operation in which only the second liquid is supplied to the mixing section and the nozzle is used to discharge the mixed liquid from the mixing section; and a second maintenance operation in which both the first liquid and the second liquid are supplied to the mixing section and the nozzle is used to discharge the mixed liquid from the mixing section. To measure the amount of the second liquid used during the first maintenance operation, A liquid dispensing method characterized by comprising adjusting the concentration of the colorant contained in the mixed liquid by supplying an amount of the first liquid corresponding to the measured amount of the second liquid to the mixing unit after the execution of the first maintenance operation.

7. A control device for controlling maintenance operations in a liquid dispensing device that dispenses a mixture of a first liquid, which is an ink containing a colorant and an auxiliary liquid, and a second liquid, which has a higher ratio of auxiliary liquid than the first liquid, from a nozzle, A supply unit that supplies the mixed liquid to the nozzle unit, and a control unit that controls the operation of the nozzle unit and controls the discharge of the mixed liquid from the nozzle unit, The system includes a measuring unit for measuring the amount of the second liquid used during the first maintenance operation, The supply unit includes a mixing unit that mixes the first liquid and the second liquid to produce the mixed liquid, The control unit, During maintenance, at least one of the following is selected and performed: a first maintenance operation in which the supply unit supplies only the second liquid to the mixing unit and the nozzle unit discharges the mixed liquid from the mixing unit; and a second maintenance operation in which the supply unit supplies both the first liquid and the second liquid to the mixing unit and the nozzle unit discharges the mixed liquid from the mixing unit. A control device characterized by adjusting the concentration of the colorant contained in the mixed liquid by supplying an amount of the first liquid corresponding to the amount of the second liquid measured by the measuring unit to the nozzle unit via the supply unit after the first maintenance operation.

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