Image forming apparatus, and operation control method

Abstract

To provide: an image forming apparatus capable of shortening wait time of user before start of image formation; and an operation control method.SOLUTION: An image forming apparatus includes: a heater which warms ink at a warming position P1 on a supply path of the ink that reaches a recording head 30; an acquisition processing portion which acquires a temperature of the ink in a specific section from the warming position P1 to the recording head 30 on the supply path; and a flow processing portion which causes, when the temperature of the ink acquired by the acquisition processing portion is lower than a predetermined threshold value, the ink warmed by the heater to flow along the supply path and a recovery path of waste ink ejected by the recording head 30 until the ink reaches the recording head 30.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an inkjet image forming apparatus and an operation control method. [Background technology]

[0002] In an image forming apparatus capable of forming an image by an inkjet method, before starting image formation, the ink used to form the image is heated to a temperature suitable for image formation. For example, an image forming apparatus is known that includes a heater that heats the ink in a supply path of the ink leading to a recording head (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-140197 Summary of the Invention [Problem to be solved by the invention]

[0004] In a conventional image forming apparatus, if the ink in the section from the heater to the print head in the supply path is cold, it takes time to warm up the ink, which means that the user has to wait a long time before image formation starts.

[0005] An object of the present invention is to provide an image forming apparatus and an operation control method that can reduce the waiting time for a user until image formation starts. [Means for solving the problem]

[0006] An image forming apparatus according to one aspect of the present invention includes a discharge unit, a first ink flow path, a second ink flow path, a heater, an acquisition processing unit, and a flow processing unit. The discharge unit discharges ink. The first ink flow path forms a supply path for the ink leading to the discharge unit. The second ink flow path forms a recovery path for waste ink discharged by the discharge unit. The heater heats the ink at a heating position on the supply path that is upstream of the discharge unit in the ink flow direction. The acquisition processing unit acquires the temperature of the ink in a specific section on the supply path from the heating position to the discharge unit. When the temperature of the ink acquired by the acquisition processing unit is less than a predetermined threshold, the flow processing unit causes the ink heated by the heater to flow along the supply path and the recovery path until it reaches the discharge unit.

[0007] According to another aspect of the present invention, an operation control method is executed by an image forming apparatus including a discharge unit that discharges ink, a first ink flow path that forms a supply path of the ink leading to the discharge unit, a second ink flow path that forms a recovery path for waste ink discharged by the discharge unit, and a heater that heats the ink at a heating position in the supply path that is upstream of the discharge unit in a flow direction of the ink, and includes an acquisition step and a flow step. In the acquisition step, the temperature of the ink in a specific section in the supply path from the heating position to the discharge unit is acquired. In the flow step, if the temperature of the ink acquired in the acquisition step is less than a predetermined threshold, the ink heated by the heater is caused to flow along the supply path and the recovery path until it reaches the discharge unit. [Effects of the Invention]

[0008] According to the present invention, it is possible to reduce the waiting time for the user until image formation starts. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the configuration of the image forming section and the transport unit of the image forming apparatus according to the embodiment of the present invention. [Figure 3] FIG. 3 is a block diagram showing the system configuration of the image forming apparatus according to the embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the configuration of an ink supply unit and an ink recovery unit of the image forming apparatus according to the embodiment of the present invention. [Figure 5] FIG. 5 is a diagram showing the configuration of a warming device of an image forming apparatus according to an embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart showing an example of an operation control process executed by the image forming apparatus according to the embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing the configuration of an ink supply unit and an ink recovery unit of an image forming apparatus according to another embodiment of the present invention. [Figure 8] FIG. 8 is a flowchart showing an example of an operation control process executed in an image forming apparatus according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following embodiment is an example of a specific embodiment of the present invention and does not limit the technical scope of the present invention.

[0011] [Configuration of image forming apparatus 100] First, the configuration of an image forming apparatus 100 according to an embodiment of the present invention will be described with reference to Figures 1 to 3. Here, Figure 1 is a cross-sectional view showing the configuration of the image forming apparatus 100. Also, Figure 2 is a plan view showing the configuration of the image forming section 3 and the transport unit 4. In Figure 1, a sheet transport path R11 is indicated by a two-dot chain line.

[0012] Image forming apparatus 100 is a printer capable of forming an image on a sheet by inkjet printing. Note that the present invention may also be applied to image forming apparatuses such as fax machines, copy machines, and multifunction peripherals that are capable of forming an image on a sheet by inkjet printing.

[0013] As shown in Figures 1 and 3, the image forming apparatus 100 includes a housing 1, a sheet conveying section 2, an image forming section 3, a conveying unit 4, an operation display section 5, a memory section 6, a control section 7, an ink supply section 8, and an ink recovery section 9.

[0014] The housing 1 houses each component of the image forming apparatus 100. A paper feed cassette 11 is removably provided in the housing 1. The paper feed cassette 11 stores sheets on which images are to be formed. A paper output tray 12 is provided on the outer surface of the housing 1. Sheets on which images are formed by the image forming unit 3 are discharged to the paper output tray 12. Inside the housing 1, the sheets stored in the paper feed cassette 11 are transported along a sheet transport path R11 (see FIG. 1) that passes through an image formation position by the image forming unit 3 and leads to the paper output tray 12.

[0015] The sheet transport unit 2 transports sheets stored in the paper feed cassette 11 along a sheet transport path R11 (see FIG. 1). As shown in FIG. 1, the sheet transport unit 2 includes a pickup roller 21 and multiple transport rollers 22. The pickup roller 21 picks up the top sheet of the stack of sheets stored in the paper feed cassette 11 and sends the sheet to the sheet transport path R11. The multiple transport rollers 22 are arranged side by side along the sheet transport path R11. Each transport roller 22 transports the sheet along the sheet transport path R11. Each transport roller 22 transports the sheet in a transport direction D11 (see FIG. 1) from the paper feed cassette 11 to the paper output tray 12.

[0016] The image forming unit 3 forms an image based on image data on a sheet supplied from the sheet conveying unit 2. As shown in FIG.

[0017] 2, each of the line heads 31 to 34 is elongated in a width direction D12 perpendicular to the conveying direction D11. Specifically, each of the line heads 31 to 34 has a length in the width direction D12 corresponding to the width of the largest size sheet that can be accommodated in the paper feed cassette 11. The line heads 31 to 34 are arranged side by side at equal intervals along the conveying direction D11.

[0018] As shown in FIG. 2, each of the line heads 31 to 34 has a plurality of recording heads 30. The recording heads 30 eject ink toward a sheet transported by the transport unit 4. Specifically, a large number of nozzles 36 (see FIG. 2) used to eject the ink are provided on the surface of the recording heads 30 facing the sheet. Each of the recording heads 30 provided in the line head 31 ejects the black ink. Each of the recording heads 30 provided in the line head 32 ejects the cyan ink. Each of the recording heads 30 provided in the line head 33 ejects the magenta ink. Each of the recording heads 30 provided in the line head 34 ejects the yellow ink. The recording heads 30 are an example of an ejection unit of the present invention.

[0019] In this embodiment, the line head 31 has three recording heads 30 arranged in a staggered pattern along the width direction D12. Similarly to the line head 31, each of the other line heads 32 to 34 also has three recording heads 30 arranged in a staggered pattern along the width direction D12. Note that Fig. 2 shows the image forming unit 3 as viewed from above in Fig. 1.

[0020] The head frame 35 supports the line heads 31 to 34. The head frame 35 is supported by the housing 1. The number of line heads provided in the image forming unit 3 may be one or more. Furthermore, the number of recording heads 30 provided in each of the line heads 31 to 34 does not have to be limited to three.

[0021] As shown in FIG. 1, the transport unit 4 is disposed below the line heads 31 to 34. The transport unit 4 transports a sheet while facing the recording head 30. For example, the transport unit 4 transports the sheet by a predetermined transport distance each time the recording head 30 ejects the ink. The transport unit 4 also stops transporting the sheet while the recording head 30 is ejecting the ink. As shown in FIG. 1, the transport unit 4 includes a transport belt 41 on which the sheet is placed, a first tension roller 42, a second tension roller 43, and a third tension roller 44 that tension the transport belt 41, and a transport frame 45 that supports these. The gap between the transport belt 41 and the recording head 30 is adjusted so that the gap between the surface of the sheet and the recording head 30 during image formation is a predetermined distance (for example, 1 mm).

[0022] The first tension roller 42 is driven to rotate by a rotational driving force supplied from a motor (not shown). As a result, the conveyor belt 41 rotates in a direction that allows the sheet to be conveyed in the conveying direction D11 (see FIG. 1). The conveying unit 4 also includes a suction unit (not shown) that sucks air through a number of through holes formed in the conveyor belt 41 to attract the sheet to the conveyor belt 41. A pressure roller 46 is provided above the first tension roller 42 to press the sheet against the conveyor belt 41 for conveyance.

[0023] The operation display unit 5 is a user interface of the image forming apparatus 100. The operation display unit 5 includes a display unit and an operation unit. The display unit displays various information in response to control instructions from the control unit 7. For example, the display unit is a liquid crystal display. The operation unit inputs various information to the control unit 7 in response to user operations. For example, the operation unit is a touch panel. The operation display unit 5 is provided on the top surface of the housing 1.

[0024] The storage unit 6 is a nonvolatile storage device. For example, the storage unit 6 is a nonvolatile memory such as a flash memory. The storage unit 6 may be an SSD (Solid State Drive) or an HDD (Hard Disk Drive).

[0025] The control unit 7 performs overall control of the image forming apparatus 100. As shown in FIG. 3, the control unit 7 includes a CPU 51, a ROM 52, and a RAM 53. The CPU 51 is a processor that executes various types of arithmetic processing. The ROM 52 is a non-volatile storage device that pre-stores information such as control programs for causing the CPU 51 to execute various types of processing. The RAM 53 is a volatile or non-volatile storage device used as a temporary storage memory (work area) for the various types of processing executed by the CPU 51. The CPU 51 performs overall control of the image forming apparatus 100 by executing the various control programs pre-stored in the ROM 52. The control unit 7 may be a control unit provided separately from a main control unit that performs overall control of the image forming apparatus 100. The control unit 7 may also be configured with an electronic circuit such as an application specific integrated circuit (ASIC).

[0026] [Configuration of ink supply unit 8 and ink recovery unit 9] Next, the configuration of the ink supply unit 8 and the ink recovery unit 9 will be described with reference to Figures 3 to 5. Here, Figure 4 is a schematic diagram showing the configuration of the ink supply unit 8 and the ink recovery unit 9. Also, Figure 5 is a cross-sectional view showing the configuration of the warming device 64. In Figure 4, the first supply flow path 62, the second supply flow path 66, and the recovery flow path 82 are indicated by thick lines.

[0027] The ink supply unit 8 supplies the ink to the recording head 30. An ink supply unit 8 is provided for each recording head 30. The configurations of the ink supply units 8 corresponding to the line heads 31 to 34 are the same except that the colors of the inks supplied are different.

[0028] As shown in Figures 3 and 4, the ink supply unit 8 includes an ink container 61, a first supply flow path 62, a first pump 63, a heating device 64, a sub-ink tank 65, a second supply flow path 66, a second pump 67, and an internal temperature sensor 68.

[0029] The ink container 61 contains the ink. For example, the ink is an aqueous ink whose main solvent is water. However, the ink may be a non-aqueous ink whose main solvent is an organic solvent or the like.

[0030] The first supply flow path 62 is an ink flow path provided between the ink container 61 and the sub-ink tank 65. The first supply flow path 62 is made of a flexible material. For example, the first supply flow path 62 is a tube made of resin.

[0031] The first pump 63 forms a part of the first supply flow path 62. The first pump 63 causes the ink in the first supply flow path 62 to flow in a first flow direction D21 (see FIG. 4) toward the recording head 30. For example, the first pump 63 is a syringe pump.

[0032] The heater 64 forms a part of the first supply flow path 62. The heater 64 heats the ink flowing through the first supply flow path 62.

[0033] As shown in FIG. 5, the heating device 64 includes a coil 71 , a container 72 , a heater 73 , a heat insulator 74 , and an ink temperature sensor 75 .

[0034] The coiled tube 71 is a tube formed in a spiral shape. The coiled tube 71 is disposed with its spiral axis aligned vertically. For example, the coiled tube 71 is formed by processing a straight metal tube into a spiral shape. The coiled tube 71 forms a part of the first supply flow path 62.

[0035] Container 72 contains coiled tube 71 and a liquid heat transfer medium M1 (see FIG. 5) used to heat coiled tube 71. For example, container 72 includes a cylindrical portion extending vertically, a disk-shaped bottom portion closing the lower end of the cylindrical portion, and a disk-shaped top plate portion closing the upper end of the cylindrical portion.

[0036] The interior of the container 72 is filled with a heat medium M1 (see FIG. 5) in an amount sufficient to submerge the spiral portion of the coiled tube 71. For example, the heat medium M1 is water. Note that the heat medium M1 is not limited to water and may be a fluid such as oil.

[0037] The heater 73 heats the container 72. Specifically, the heater 73 is a so-called planar heater. For example, the heater 73 includes a heating wire and a metal sheet such as aluminum that covers the heating wire. The heater 73 is provided to cover the outer surface of the container 72. In the heating device 64, the heater 73 heats the container 72, thereby heating the heat medium M1 contained in the container 72. As a result, the ink flowing inside the spiral portion disposed in the heat medium M1 is heated to the same temperature as the heat medium M1.

[0038] The heat insulating material 74 is provided so as to cover the outer peripheral surface of the container 72. The heater 73 is provided between the container 72 and the heat insulating material 74. For example, the heat insulating material 74 is provided so as to cover the entire outer surface of the container 72.

[0039] The ink temperature sensor 75 is used to detect the temperature of the ink heated by the heating device 64. For example, the ink temperature sensor 75 is a contact-type temperature sensor that is provided in contact with the heat medium M1. The ink temperature sensor 75 outputs a first detection signal that includes a signal value that corresponds to the temperature of the heat medium M1 that it contacts. The first detection signal output from the ink temperature sensor 75 is input to the control unit 7.

[0040] The heater 64 may be configured to heat the ink without using the heat medium M1.

[0041] The sub-ink tank 65 stores the ink supplied from the ink container 61. The ink stored in the sub-ink tank 65 is supplied to the recording head 30.

[0042] The second supply flow path 66 is an ink flow path provided between the sub-ink tank 65 and the recording head 30. The second supply flow path 66 is made of a flexible material. For example, the second supply flow path 66 is a tube made of resin.

[0043] The second pump 67 forms a part of the second supply flow path 66. The second pump 67 causes the ink in the second supply flow path 66 to flow in a second flow direction D22 (see FIG. 4). For example, the second pump 67 is a syringe pump.

[0044] The internal temperature sensor 68 detects the air temperature inside the housing of the image forming apparatus 100 (internal temperature). The internal temperature sensor 68 is provided inside the housing of the image forming apparatus 100. The internal temperature sensor 68 outputs a second detection signal including a signal value according to the air temperature inside the housing. The second detection signal output from the internal temperature sensor 68 is input to the control unit 7.

[0045] The first supply flow path 62 and the second supply flow path 66 form an ink supply path leading to the recording head 30. A heater 73 of the heating device 64 heats the ink at a heating position P1 (see FIG. 4) upstream of the recording head 30 in the ink supply direction D20 (see FIG. 4). A sub-ink tank 65 is provided in a specific section of the supply path from the heating position P1 to the recording head 30. A first pump 63 is provided upstream of the sub-ink tank 65 in the supply direction D20 in the supply path, and supplies the ink heated by the heater 73 to the sub-ink tank 65. A second pump 67 is provided downstream of the sub-ink tank 65 in the supply path in the supply direction D20, and sucks up the ink from the sub-ink tank 65 in an amount equal to the amount of ink supplied by the first pump 63 and supplies it to the recording head 30. The first supply flow path 62 and the second supply flow path 66 are examples of a first ink flow path according to the present invention. The supply direction D20 is an example of a flow direction of the present invention. The sub-ink tank 65 is an example of a storage section of the present invention.

[0046] The ink recovery unit 9 recovers the ink (waste ink) ejected by the recording head 30. For example, an ink recovery unit 9 is provided for each recording head 30. The ink recovery units 9 corresponding to the line heads 31 to 34 have the same configuration except that the colors of the ink recovered are different. The ink recovery units 9 may be provided corresponding to multiple recording heads 30.

[0047] As shown in FIGS. 3 and 4, the ink recovery unit 9 includes an ink receiving unit 81, a recovery passage 82, a third pump 83, and a waste ink storage unit 84.

[0048] The ink receiving unit 81 receives the waste ink ejected by the recording head 30. The ink receiving unit 81 is provided so as to be movable between a facing position below the recording head 30 where it faces the recording head 30, and a retracted position where it is retracted horizontally from the facing position. When an image is formed on a sheet, the ink receiving unit 81 is moved to the retracted position.

[0049] The recovery flow path 82 is an ink flow path provided between the ink receiving section 81 and the waste ink collection section 84. The recovery flow path 82 is made of a flexible material. For example, the recovery flow path 82 is a tube made of resin.

[0050] The third pump 83 forms a part of the recovery passageway 82. The third pump 83 causes the waste ink in the recovery passageway 82 to flow in a third flow direction D23 (see FIG. 4). For example, the third pump 83 is a syringe pump.

[0051] The waste ink storage section 84 stores the waste ink ejected by the recording head 30 .

[0052] The recovery flow path 82 forms a path for recovering the waste ink ejected by the recording head 30. The recovery flow path 82 is an example of the second ink flow path of the present invention.

[0053] In the image forming apparatus 100, before starting image formation, the heater 73 of the heating device 64 heats the ink to a temperature suitable for forming an image.

[0054] Incidentally, in a conventional image forming apparatus, if the ink in the specific section from the heating position P1 (see FIG. 4) in the supply path to the recording head 30 is cold, it takes time to heat the ink. Therefore, in a conventional image forming apparatus, if the ink in the specific section is cold, the user has to wait a long time until image formation starts.

[0055] In contrast to this, the image forming apparatus 100 according to the embodiment of the present invention can reduce the waiting time for the user until image formation starts, as will be described below.

[0056] [Configuration of control unit 7] Next, the configuration of the control unit 7 will be described in more detail with reference to FIG.

[0057] As shown in FIG. 3, the control unit 7 includes a drive control unit 91, an acquisition processing unit 92, a flow processing unit 93, a setting processing unit 94, and a switching processing unit 95.

[0058] Specifically, an operation control program for causing the CPU 51 to function as each of the above-mentioned functional units is stored in advance in the ROM 52 of the control unit 7. The CPU 51 executes the operation control program stored in the ROM 52 to function as each of the above-mentioned functional units.

[0059] The operation control program may be recorded on a computer-readable recording medium such as a CD, DVD, or flash memory, and may be read from the recording medium and stored in a storage device such as the memory unit 6. Some or all of the above-mentioned functional units may be configured with electronic circuits such as application-specific integrated circuits (ASICs). The operation control program may also be a program for causing multiple processors to function as the functional units included in the control unit 7.

[0060] The drive control unit 91 controls the drive of the heater 73 based on the difference between the temperature of the ink at the heating position P1 (see FIG. 4) and a preset target temperature.

[0061] Specifically, the drive control unit 91 controls the power supply to the heater 73 so that the first detected temperature detected by the ink temperature sensor 75 becomes the target temperature. For example, the drive control unit 91 controls the driving of the heater 73 using PID control. For example, in the image forming apparatus 100, a switching element (not shown) that can switch the conduction and interruption of the power supply path between a power source (not shown) and the heater 73 is provided on the power supply path. The drive control unit 91 inputs a PWM signal having a duty ratio corresponding to the difference between the first detected temperature and the target temperature to the switching element, thereby controlling the on / off of the switching element. As a result, the amount of power supplied to the heater 73 is adjusted according to the difference between the first detected temperature and the target temperature.

[0062] The acquisition processing unit 92 acquires the temperature of the ink in the specific section.

[0063] For example, when the image forming device 100 transitions from a power-saving state in which power consumption is reduced compared to the normal state to the normal state, the acquisition processing unit 92 acquires the temperature of the ink in the specific section based on the elapsed time since the previous transition to the power-saving state and the air temperature at the installation location of the image forming device 100.

[0064] Here, the power saving state is a state in which power supply to the image forming unit 3 is stopped and the image forming apparatus 100 is unable to form images. The normal state is a state in which power is supplied to the image forming unit 3 and the image forming apparatus 100 is able to form images. For example, when the image forming apparatus 100 is in the normal state, the control unit 7 transitions the image forming apparatus 100 to the power saving state upon receiving a user operation instructing the transition to the power saving state or upon a predetermined time having elapsed since the last user operation was received. Furthermore, when the image forming apparatus 100 is in the power saving state, the control unit 7 transitions the image forming apparatus 100 to the normal state upon receiving a user operation. The power saving state is an example of a first state of the present invention. The normal state is an example of a second state. The first state of the present invention may include a state in which the image forming apparatus 100 is powered off.

[0065] For example, when the image forming apparatus 100 transitions from the normal state to the power saving state, the acquisition processing unit 92 records the current time. Furthermore, when the image forming apparatus 100 transitions from the power saving state to the normal state, the acquisition processing unit 92 acquires the elapsed time since the previous transition to the power saving state, i.e., the duration of the power saving state, based on the last recorded time of transition to the power saving state and the current time.

[0066] The acquisition processing unit 92 also acquires the second detected temperature detected by the internal temperature sensor 68 as the air temperature at the installation location of the image forming apparatus 100. The acquisition processing unit 92 may also acquire the air temperature at the installation location of the image forming apparatus 100 using a temperature sensor provided outside the housing of the image forming apparatus 100.

[0067] The acquisition processing unit 92 then acquires the current temperature of the ink in the specific section based on the acquired time elapsed since the previous transition to the power saving state, the acquired air temperature at the installation location of the image forming apparatus 100, and the temperature of the ink at the previous transition to the power saving state. Here, when the image forming apparatus 100 is in the normal state, the temperature of the ink is maintained at a predetermined optimum printing temperature. That is, the temperature of the ink at the previous transition to the power saving state is the optimum printing temperature. The optimum printing temperature is a predetermined temperature within a printable temperature range. The printable temperature range is a temperature range of the ink that can form an image with image quality exceeding a predetermined reference level. The printable temperature range and the optimum printing temperature are predetermined based on the type of ink.

[0068] For example, the acquisition processing unit 92 calculates the current ink temperature in the specific section by substituting the acquired time elapsed since the previous transition to the power saving state, the acquired air temperature at the installation location of the image forming apparatus 100, and the optimal printing temperature into a predetermined first calculation formula. Note that, if the acquired time elapsed since the previous transition to the power saving state exceeds a predetermined time, the acquisition processing unit 92 may determine that the current ink temperature in the specific section is the same as the acquired air temperature at the installation location of the image forming apparatus 100.

[0069] The image forming apparatus 100 may be provided with a temperature sensor capable of detecting the temperature of the ink in the specific section. In this case, the acquisition processing unit 92 may acquire the temperature of the ink in the specific section using the temperature sensor. The acquisition processing unit 92 may also acquire the first detected temperature detected by the ink temperature sensor 75 before driving the heater 73 as the temperature of the ink in the specific section.

[0070] When the temperature of the ink acquired by the acquisition processing unit 92 is less than a predetermined threshold, the flow processing unit 93 causes the ink heated by the heater 73 to flow along the supply path and the recovery path until the ink reaches the recording head 30.

[0071] For example, the threshold value is the same as the lower limit of the printable temperature range. In other words, the flow processing unit 93 flows the ink when the image forming apparatus 100 is not capable of forming an image with image quality exceeding the reference level.

[0072] Specifically, the flow processing unit 93 causes the ink to flow along the supply path and the recovery path using the first pump 63, the second pump 67, and the third pump 83. When causing the ink to flow, the flow processing unit 93 moves the ink receiving unit 81 to the opposing position.

[0073] Here, the flow processing unit 93 uses the second pump 67 to suck up the ink from the sub-ink tank 65, and then uses the first pump 63 to supply the ink heated by the heater 73 to the sub-ink tank 65. As a result, after the amount of cooled ink contained in the sub-ink tank 65 decreases, the ink heated by the heater 73 is supplied to the sub-ink tank 65. Therefore, it is possible to effectively increase the temperature of the ink in the sub-ink tank 65.

[0074] For example, when the number of times the first pump 63 and the second pump 67 are driven reaches a predetermined specific number, the flow processing unit 93 determines that the ink heated by the heater 73 has reached the recording head 30. The specific number is determined based on the amount of ink flowed by the first pump 63 and the second pump 67, the amount of ink stored in the section of the first supply flow path 62 from the heating position P1 to the sub-ink tank 65, and the amount of ink stored in the second supply flow path 66.

[0075] The setting processing unit 94 sets the target temperature based on the ink temperature acquired by the acquisition processing unit 92 .

[0076] For example, when the ink temperature acquired by the acquisition processing unit 92 is equal to or higher than the threshold value, the setting processing unit 94 sets the optimum printing temperature as the target temperature.

[0077] In addition, when the temperature of the ink acquired by the acquisition processing unit 92 is less than the threshold value, the setting processing unit 94 sets the target temperature so that the temperature of the ink in the sub-ink tank 65 becomes the optimal printing temperature (an example of a specific value of the present invention) by supplying the ink after heating it by driving the first pump 63.

[0078] For example, the temperature of the ink after heating (hereinafter referred to as the "specific temperature"), at which the temperature of the ink in the sub-ink tank 65 becomes the optimum printing temperature due to the supply of the heated ink by driving the first pump 63, can be calculated based on the following first, second, third, and fourth values. The first value is a value indicating the amount of ink stored in the sub-ink tank 65 after the second pump 67 has sucked up the ink from the sub-ink tank 65 and before the first pump 63 has supplied the ink to the sub-ink tank 65. The second value is a value indicating the amount of ink supplied to the sub-ink tank 65 by the first pump 63. The third value is a value indicating the amount of ink present in the section of the first supply flow path 62 from the heating position P1 to the sub-ink tank 65. The fourth value is a value indicating the temperature of the ink acquired by the acquisition processing unit 92.

[0079] In other words, the amount of ink heated by the heater 73 and supplied to the sub-ink tank 65 by the first pump 63 is the amount of ink supplied to the sub-ink tank 65 by the first pump 63 (the second value) minus the amount of ink present in the section of the first supply flow path 62 from the heating position P1 to the sub-ink tank 65 (the third value). Furthermore, the amount of cooled ink mixed with the heated ink supplied to the sub-ink tank 65 by the first pump 63 in the sub-ink tank 65 is the sum of the amount of ink stored in the sub-ink tank 65 (the first value) after the second pump 67 has sucked up the ink from the sub-ink tank 65 and before the first pump 63 has supplied the ink to the sub-ink tank 65 (the third value). Furthermore, the temperature of the cooled ink is acquired by the acquisition processing unit 92. The temperature of the ink after heating (the specific temperature) can be calculated by mixing the cooled ink and the heated ink to bring the temperature of the ink in the sub-ink tank 65 to the optimum printing temperature.

[0080] For example, the setting processing unit 94 acquires the amount of ink stored in the sub-ink tank 65 before the ink is flowed by the flow processing unit 93, using a water level sensor (not shown) that can detect the level of the ink contained in the sub-ink tank 65. The setting processing unit 94 also acquires the amount of ink stored in the sub-ink tank 65 (the first value) after the ink is sucked up from the sub-ink tank 65 by the second pump 67 and before the ink is supplied to the sub-ink tank 65 by the first pump 63, by subtracting the known amount of ink sucked up from the sub-ink tank 65 by the second pump 67 (the second value) from the acquired amount of stored ink. The setting processing unit 94 also calculates the specific temperature by substituting the temperature of the ink acquired by the acquisition processing unit 92 (the fourth value), the acquired amount of stored ink (the first value), and the known second and third values ​​into a predetermined second calculation formula.

[0081] If the calculated specific temperature exceeds a predetermined upper limit temperature, the setting processing unit 94 sets the upper limit temperature as the target temperature instead of the specific temperature. The upper limit temperature is a temperature determined based on the type of ink. This makes it possible to avoid deterioration of the ink due to excessive temperature rise.

[0082] Table data indicating the correspondence between the ink temperature acquired by the acquisition processing unit 92 and the temperature value used to set the target temperature may be stored in advance in the storage unit 6. The table data may define the correspondence between the ink temperature acquired by the acquisition processing unit 92 and the temperature value so that the lower the ink temperature acquired by the acquisition processing unit 92, the higher the temperature value. In this case, when the ink temperature acquired by the acquisition processing unit 92 is below the threshold value, the setting processing unit 94 may set the temperature value associated with the ink temperature in the table data as the target temperature.

[0083] Alternatively, the target temperature may always be the optimum printing temperature. In this case, the control unit 7 does not need to include the setting processing unit 94.

[0084] The switching processing unit 95 switches between enabling and disabling the ink flow function of the flow processing unit 93 in response to a user operation.

[0085] For example, the switching processing unit 95 displays a function setting screen used to switch between enabling and disabling the ink flow function on the operation display unit 5 in response to a predetermined operation on the operation display unit 5. Then, the switching processing unit 95 switches between enabling and disabling the ink flow function in response to a user's operation on the function setting screen. This allows the user to select whether to prioritize reducing ink consumption or shortening the waiting time until image formation starts.

[0086] Here, when the temperature of the ink acquired by the acquisition processing unit 92 is less than the threshold value, the flow processing unit 93 causes the ink to flow if the ink flow function is enabled, and does not cause the ink to flow if the ink flow function is disabled.

[0087] [Motion control processing] 6, an example of the procedure of the operation control process executed by the control unit 7 in the image forming apparatus 100 and the operation control method of the present invention will be described. Here, steps S11, S12, etc. represent the numbers of the processing procedures (steps) executed by the control unit 7. The operation control process is executed when the image forming apparatus 100 transitions from the power saving state to the normal state.

[0088] <Step S11> First, in step S11, the control unit 7 acquires the temperature of the ink in the specific section. Here, the process of step S11 is an example of an acquisition step of the present invention, and is executed by the acquisition processing unit 92 of the control unit 7.

[0089] Specifically, the control unit 7 acquires the time elapsed since the most recent transition to the power saving state based on the last recorded time of transition to the power saving state and the current time. The control unit 7 also acquires the second detected temperature detected by the internal temperature sensor 68 as the air temperature at the installation location of the image forming apparatus 100. The control unit 7 then calculates the current ink temperature in the specific section by substituting the acquired time elapsed since the most recent transition to the power saving state, the acquired air temperature at the installation location of the image forming apparatus 100, and the optimal printing temperature into the first calculation formula.

[0090] <Step S12> In step S12, the control unit 7 determines whether the temperature of the ink obtained in the process of step S11 is lower than the threshold value.

[0091] Here, if the control unit 7 determines that the temperature of the ink is less than the threshold value (Yes in S12), it shifts the process to step S13. On the other hand, if the temperature of the ink is not less than the threshold value (No in S12), it shifts the process to step S21.

[0092] <Step S13> In step S13, the control unit 7 determines whether the ink flow function is enabled.

[0093] Here, if the control unit 7 determines that the ink flow function is enabled (Yes in S13), it shifts the process to step S14. On the other hand, if the ink flow function is not enabled (No in S13), it shifts the process to step S21.

[0094] <Step S14> In step S14, the control unit 7 sets the specific temperature or the upper limit temperature as the target temperature. The process of step S14 is an example of a setting step of the present invention, and is executed by the setting processing unit 94 of the control unit 7.

[0095] Specifically, the control unit 7 uses the water level sensor to obtain the current amount of ink stored in the sub-ink tank 65. The control unit 7 then subtracts the known amount of ink suctioned from the sub-ink tank 65 by the second pump 67 (the second value) from the obtained amount of ink stored, thereby obtaining the amount of ink stored in the sub-ink tank 65 after the second pump 67 suctions the ink from the sub-ink tank 65 and before the first pump 63 supplies the ink to the sub-ink tank 65 (the first value). The control unit 7 then calculates the specific temperature by substituting the ink temperature (the fourth value) obtained by the process of step S11, the obtained amount of ink stored (the first value), and the known second and third values ​​into the second calculation formula. If the calculated specific temperature is equal to or lower than the upper limit temperature, the control unit 7 sets the specific temperature as the target temperature. If the calculated specific temperature exceeds the upper limit temperature, the control unit 7 sets the upper limit temperature as the target temperature.

[0096] <Step S15> In step S15, the control unit 7 starts drive control of the heater 73 based on the difference between the temperature of the ink at the heating position P1 and the target temperature set in the process of step S14. Here, the process of step S15 is executed by the drive control unit 91 of the control unit 7.

[0097] Specifically, the control unit 7 controls the power supplied to the heater 73 so that the first detected temperature detected by the ink temperature sensor 75 becomes the target temperature.

[0098] <Step S16> In step S16, the control unit 7 drives the second pump 67. Specifically, the control unit 7 drives the second pump 67 once. As a result, the ink in the amount of the second value is sucked up from the sub-ink tank 65, and the sucked up ink is supplied to the recording head 30. Note that in step S16, the control unit 7 may drive the second pump 67 multiple times.

[0099] In addition, when the ink is ejected from the recording head 30 to the ink receiving section 81 by driving the second pump 67, the control section 7 uses the third pump 83 to cause the ink ejected to the ink receiving section 81 to flow along the recovery path.

[0100] <Step S17> In step S17, the control unit 7 drives the first pump 63. Specifically, the control unit 7 drives the first pump 63 once. As a result, the ink is sucked up from the ink container 61, and the ink in the second amount, including the ink heated by the heater 73, is supplied to the sub-ink tank 65. Note that in step S17, the control unit 7 may drive the first pump 63 multiple times.

[0101] Here, in the operation control process, the process of step S17 is executed after the process of step S16. This makes it possible to reduce the amount of cooled ink stored in the sub-ink tank 65, and then supply the ink heated by the heater 73 to the sub-ink tank 65. Therefore, it is possible to effectively increase the temperature of the ink in the sub-ink tank 65.

[0102] Furthermore, in the operation control process, the ink heated to the specific temperature or the upper limit temperature by the heater 73 is supplied to the sub-ink tank 65. When the ink heated to the specific temperature is supplied, it is possible to adjust the temperature of the ink in the sub-ink tank 65 to the optimum printing temperature. When the ink heated to the upper limit temperature is supplied, it is possible to bring the temperature of the ink in the sub-ink tank 65 as close to the optimum printing temperature as possible and to avoid deterioration of the ink due to excessive heating.

[0103] The control unit 7 may change the target temperature to the optimum printing temperature after the first execution of step S17, thereby preventing the temperature of the ink in the sub-ink tank 65 from rising above the printable temperature when step S17 is executed for the second time.

[0104] <Step S18> In step S18, the control unit 7 determines whether the heated ink has reached the recording head 30. Here, the processes of steps S16, S17, and S18 are an example of a flow step of the present invention, and are executed by the flow processing unit 93 of the control unit 7.

[0105] Specifically, the control unit 7 determines that the heated ink has reached the recording head 30 when the number of times that the processes of step S16 and step S17 have been executed reaches the specific number of times.

[0106] Here, when the control unit 7 determines that the heated ink has reached the recording head 30 (Yes in S18), it ends the operation control process. On the other hand, when the heated ink has not reached the recording head 30 (No in S18), the control unit 7 shifts the process to step S16. As a result, the second pump 67 and the first pump 63 are driven until the heated ink reaches the recording head 30.

[0107] <Step S21> In step S21, the control unit 7 sets the optimum print temperature as the target temperature. The process of step S21 is an example of a setting step of the present invention, and is executed by the setting processing unit 94 of the control unit 7.

[0108] <Step S22> In step S22, the control unit 7 starts drive control of the heater 73 based on the difference between the temperature of the ink at the heating position P1 and the target temperature set in the process of step S21. Here, the process of step S22 is executed by the drive control unit 91 of the control unit 7.

[0109] In this way, in the image forming apparatus 100, when the temperature of the ink acquired by the acquisition processing unit 92 is lower than the threshold value, the ink is caused to flow along the supply path and the recovery path until the ink heated by the heater 73 reaches the recording head 30. This makes it possible to replace the cooled ink present in the specific section with the ink heated by the heater 73. This makes it possible to shorten the time the user has to wait until image formation starts.

[0110] [Other embodiments] The image forming apparatus 100 may also include a circulation flow path 69 shown in FIG.

[0111] The circulation flow path 69 is an ink flow path provided between the recording head 30 and the sub-ink tank 65. The circulation flow path 69, together with the second supply flow path 66, forms a circulation path for the ink passing through the recording head 30 and the sub-ink tank 65. The circulation flow path 69 is an example of the third ink flow path of the present invention.

[0112] When the image forming apparatus 100 includes a circulation flow path 69, the flow processing unit 93 may perform a first flow process and a second flow process. The first flow process is a process of causing the ink to flow along the supply path and the recovery path. The second flow process is a process of causing the ink to flow along the circulation path. The first flow process is performed using the first pump 63, the second pump 67, the third pump 83, and an on-off valve that can switch between allowing and prohibiting the flow of the ink in the circulation flow path 69. Specifically, in the first flow process, the second pump 67 is driven in a state in which the on-off valve prohibits the flow of the ink in the circulation flow path 69. Furthermore, the second flow process is performed using the second pump 67 and the on-off valve. Specifically, in the second flow process, the second pump 67 is driven in a state in which the on-off valve allows the flow of the ink in the circulation flow path 69.

[0113] Furthermore, the flow processing unit 93 may execute the second flow process after the ink heated by the heater 73 through execution of the first flow process reaches the sub-ink tank 65. This allows the cooled ink in the circulation flow path 69 to be replaced with the ink heated by the heater 73.

[0114] The operation control process may include steps S31 to S34 shown in FIG. 8 instead of steps S16 to S18.

[0115] <Step S31> In step S31, the control unit 7 executes the first flow process. Specifically, the control unit 7 drives the second pump 67 while keeping the on-off valve closed. As a result, the ink in the amount of the second value is sucked up from the sub-ink tank 65, and the sucked up ink flows along the supply flow path and the recovery flow path. Furthermore, after driving the second pump 67, the control unit 7 drives the first pump 63. As a result, the ink is sucked up from the ink container 61, and the ink in the amount of the second value, including the ink heated by the heater 73, is supplied to the sub-ink tank 65. As a result, the temperature of the ink in the sub-ink tank 65 is adjusted to the optimum printing temperature.

[0116] <Step S32> In step S32, the control unit 7 executes the second flow process. Specifically, the control unit 7 drives the second pump 67 with the on-off valve open. As a result, the ink in the sub-ink tank 65, which has been adjusted to the optimum printing temperature by the process of step S31, is supplied to the recording head 30. In addition, the cooled ink in the circulation flow path 69 is supplied to the sub-ink tank 65.

[0117] <Step S33> In step S33, the control unit 7 determines whether the heated ink has reached the recording head 30. Here, the processes of steps S31, S32, and S33 are executed by the flow processing unit 93 of the control unit 7.

[0118] Specifically, the control unit 7 determines that the heated ink has reached the recording head 30 when the number of times that the processes of step S31 and step S32 have been executed reaches the specific number of times.

[0119] Here, if the control unit 7 determines that the heated ink has reached the recording head 30 (Yes in S33), it ends the operation control process. On the other hand, if the heated ink has not reached the recording head 30 (No in S33), the control unit 7 shifts the process to step S31.

[0120] By performing the above-described processes from step S31 to step S34, it is possible to replace the cooled ink in the circulation flow path 69 with the ink heated by the heater 73. Therefore, it is possible to reduce variations in the temperature of the ink in the circulation path.

[0121] Furthermore, the image forming apparatus 100 does not need to be equipped with the sub-ink tank 65. In other words, the recording head 30 may receive the ink supply directly from the ink container 61. In this case, the control unit 7 does not need to include the setting processing unit 94.

[0122] [Notes on the Invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0123] <Appendix 1> an ink supply path for the ink leading to the ejection portion; a second ink flow path for the ink ejected by the ejection portion; a heater for heating the ink at a heating position upstream of the ejection portion in the ink flow direction in the supply path; an acquisition processing unit for acquiring the temperature of the ink in a specific section of the supply path from the heating position to the ejection portion; and a flow processing unit for causing the ink heated by the heater to flow along the supply path and the recovery path until the ink reaches the ejection portion when the temperature of the ink acquired by the acquisition processing unit is less than a predetermined threshold.

[0124] <Appendix 2> The image forming device described in Appendix 1, wherein when the image forming device transitions from a first state in which image formation is not possible to a second state in which image formation is possible, the acquisition processing unit acquires the temperature of the ink in the specific section based on the elapsed time since the previous transition to the first state and the air temperature at the installation location of the image forming device.

[0125] <Appendix 3> An image forming apparatus as described in Appendix 1 or 2, which is provided with a switching processing unit that switches the ink flow function of the flow processing unit between enabled and disabled in response to user operation, and the flow processing unit causes the ink to flow if the ink flow function is enabled when the temperature of the ink acquired by the acquisition processing unit is below the threshold, and does not cause the ink to flow if the ink flow function is disabled.

[0126] <Appendix 4> An image forming apparatus as described in any of Appendices 1 to 3, comprising: a storage section provided in the specific section for storing the ink; and a third ink flow path that, together with the first ink flow path, forms a circulation path for the ink passing through the ejection section and the storage section, wherein the flow processing section performs a second flow process for causing the ink to flow along the circulation path after the ink, which has been heated by the heater, reaches the storage section by performing a first flow process for causing the ink to flow along the supply path and the recovery path.

[0127] <Appendix 5> An operation control method executed in an image forming device having an ejection unit that ejects ink, a first ink flow path that forms a supply path for the ink leading to the ejection unit, a second ink flow path that forms a recovery path for waste ink ejected by the ejection unit, and a heater that heats the ink at a heating position in the supply path that is upstream of the ejection unit in the flow direction of the ink, the operation control method including: an acquisition step that acquires the temperature of the ink in a specific section in the supply path from the heating position to the ejection unit; and a flow step that, when the temperature of the ink acquired by the acquisition step is less than a predetermined threshold, causes the ink heated by the heater to flow along the supply path and the recovery path until it reaches the ejection unit. [Explanation of symbols]

[0128] 1 chassis 2 Sheet transport section 3 Image forming unit 4 Transport unit 5 Operation display section 6 Memory section 7 Control Unit 8 Ink supply unit 9 Ink recovery section 30 Recording head 61 Ink Container 62 First supply channel 63 First Pump 64 Warming device 65 Sub ink tank 66 Second supply channel 67 Second Pump 68 In-flight temperature sensor 69 Circulation flow path 73 Heater 75 Ink temperature sensor 81 Ink receiver 82 Recovery channel 83 Third Pump 84 Waste ink storage compartment 91 Drive control unit 92 Acquisition processing unit 93 Fluid Processing Section 94 Setting processing section 95 Switching processing section 100 Image forming device

Claims

1. An ejection unit that ejects ink; a first ink flow path forming a supply path of the ink leading to the ejection portion; a second ink flow path forming a recovery path for waste ink discharged by the discharge unit; a heater that heats the ink at a heating position upstream of the ejection portion in the ink flow direction in the supply path; an acquisition processing unit that acquires a temperature of the ink in a specific section from the heating position to the ejection unit in the supply path; a flow processing unit that, when the temperature of the ink acquired by the acquisition processing unit is less than a predetermined threshold, causes the ink heated by the heater to flow along the supply path and the recovery path until the ink reaches the ejection unit; An image forming apparatus comprising:

2. when the image forming apparatus transitions from a first state in which image formation is not possible to a second state in which image formation is possible, the acquisition processing unit acquires the temperature of the ink in the specific section based on the elapsed time from the previous transition to the first state and the air temperature at a location where the image forming apparatus is installed. The image forming apparatus according to claim 1 .

3. a switching processing unit that switches an ink flow function by the flow processing unit between enabled and disabled in response to a user operation; when the temperature of the ink acquired by the acquisition processing unit is less than the threshold value, if the ink flow function is enabled, the flow processing unit causes the ink to flow, and if the ink flow function is disabled, the flow processing unit does not cause the ink to flow.

3. The image forming apparatus according to claim 1 or 2.

4. a storage section provided in the specific section and configured to store the ink; a third ink flow path that, together with the first ink flow path, forms a circulation path for the ink passing through the ejection portion and the storage portion; Equipped with the flow processing unit executes a second flow process to cause the ink to flow along the circulation path after the ink heated by the heater reaches the storage unit through execution of a first flow process to cause the ink to flow along the supply path and the recovery path.

3. The image forming apparatus according to claim 1 or 2.

5. An operation control method executed in an image forming apparatus including: a discharge unit that discharges ink; a first ink flow path that forms a supply path of the ink leading to the discharge unit; a second ink flow path that forms a recovery path for waste ink discharged by the discharge unit; and a heater that heats the ink at a heating position upstream of the discharge unit in a flow direction of the ink in the supply path, the method comprising: acquiring a temperature of the ink in a specific section from the heating position to the ejection unit in the supply path; a flowing step of causing the ink heated by the heater to flow along the supply path and the recovery path until the ink reaches the ejection portion when the temperature of the ink obtained by the obtaining step is less than a predetermined threshold value; The motion control method includes:

Images