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; a sub ink tank 65 provided in a specific section from the warming position P1 to the recording head 30 on the supply path; an acquisition processing portion which acquires a temperature of the ink in the specific section; 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; and a setting processing portion which sets, based on the temperature of the ink acquired by the acquisition processing portion, a target temperature used for drive control of the heater.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an inkjet type 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 forming the image. For example, there is known an image forming apparatus equipped with a heater that heats the ink on a supply path of the ink leading to a recording head (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-140197 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a conventional image forming apparatus, when the ink in the section from the heater to the recording head in the supply path is cold, it takes time to warm up the ink, and therefore, in the conventional image forming apparatus, when the ink in the section is cold, the user has to wait a long time until 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 of 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, a storage unit, a drive control unit, an acquisition processing unit, a flow processing unit, and a setting 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 upstream of the discharge unit in a flow direction of the ink in the supply path. The storage unit is provided in a specific section of the supply path from the heating position to the discharge unit, and stores the ink. The drive control unit controls driving of the heater based on a difference between a temperature of the ink at the heating position and a preset target temperature. The acquisition processing unit acquires the temperature of the ink in the specific section. 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 the ink reaches the ejection unit. The setting processing unit sets the target temperature based on the temperature of the ink acquired by the acquisition processing unit.

[0007] According to another aspect of the present invention, an operation control method is executed by an image forming apparatus including an ejection section that ejects ink, a first ink flow path that forms a supply path of the ink leading to the ejection section, a second ink flow path that forms a recovery path for waste ink ejected by the ejection section, a heater that heats the ink at a heating position upstream of the ejection section in the flow direction of the ink in the supply path, a storage section that is provided in a specific section in the supply path from the heating position to the ejection section and stores the ink, and a drive control section that controls driving of the heater based on a difference between a temperature of the ink at the heating position and a preset target temperature, and includes an acquisition step, a flow step, and a setting step. In the acquisition step, the temperature of the ink in the specific section is acquired. In the flow step, if the temperature of the ink acquired in the acquisition step is less than a predetermined threshold value, the ink heated by the heater is caused to flow along the supply path and the recovery path until it reaches the ejection section. In the setting step, the target temperature is set based on the temperature of the ink acquired in the acquisition step. Effect of the Invention

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

[0009] [Figure 1] FIG. 1 is a diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing the configuration of an image forming section and a transport unit of the image forming apparatus according to the embodiment of the present invention. [Diagram 3] FIG. 3 is a block diagram showing a 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. [Diagram 5]FIG. 5 is a diagram showing a 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 in 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 PREFERRED EMBODIMENTS

[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 the present invention, and is not intended to 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 Fig. 1 to Fig. 3. Fig. 1 is a cross-sectional view showing the configuration of the image forming apparatus 100. Fig. 2 is a plan view showing the configuration of an image forming section 3 and a transport unit 4. In Fig. 1, a sheet transport path R11 is indicated by a two-dot chain line.

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

[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 of the components of the image forming apparatus 100. A paper feed cassette 11 is removably provided in the housing 1. The paper feed cassette 11 houses sheets on which images are 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 output to the paper output tray 12. Inside the housing 1, the sheets housed 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 reaches the paper output tray 12.

[0015] The sheet transport unit 2 transports the 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 a plurality of transport rollers 22. The pickup roller 21 picks up the top sheet of the sheet stack stored in the paper feed cassette 11 and sends the sheet to the sheet transport path R11. The plurality of transport rollers 22 are arranged side by side along the sheet transport path R11. Each of the transport rollers 22 transports the sheet along the sheet transport path R11. Each of the transport rollers 22 transports the sheet in a transport direction D11 (see FIG. 1) from the paper feed cassette 11 to the paper discharge 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 transport 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 sheet among the sheets 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 transport 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 for ejecting 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 section of the present invention.

[0019] In this embodiment, the line head 31 has three recording heads 30 arranged in a staggered manner 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 manner 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 need 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 the sheet while facing the recording head 30. For example, the transport unit 4 transports the sheet by a predetermined transport amount every time the recording head 30 ejects the ink. The transport unit 4 stops transporting the sheet while the recording head 30 ejects 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 stretch the transport belt 41, and a transport frame 45 that supports them. 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 rotationally driven by a rotational driving force supplied from a motor (not shown). As a result, the conveyor belt 41 rotates in a direction capable of conveying the sheet in the conveying direction D11 (see FIG. 1). The conveyor unit 4 is also provided with a suction unit (not shown) that sucks air through a number of through holes formed in the conveyor belt 41 in order 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 non-volatile storage device. For example, the storage unit 6 is a non-volatile memory such as a flash memory. The storage unit 6 may be a solid state drive (SSD) or a hard disk drive (HDD).

[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 performs various arithmetic processing. The ROM 52 is a non-volatile storage device in which information such as a control program for causing the CPU 51 to perform various processing is stored in advance. The RAM 53 is a volatile or non-volatile storage device used as a temporary storage memory (work area) for various processing performed by the CPU 51. The CPU 51 performs overall control of the image forming apparatus 100 by executing various control programs stored in advance 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 integrated circuit (ASIC).

[0026] [Configuration of the ink supply unit 8 and the ink recovery unit 9] Next, the configurations of the ink supply unit 8 and the ink recovery unit 9 will be described with reference to Fig. 3 to Fig. 5. Fig. 4 is a schematic diagram showing the configurations of the ink supply unit 8 and the ink recovery unit 9. Fig. 5 is a cross-sectional view showing the configuration of the warming device 64. In Fig. 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 ink supply units 8 corresponding to the line heads 31 to 34 have the same configuration, 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.

[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 resin tube.

[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 heating device 64 forms a part of the first supply flow path 62. The heating device 64 heats the ink flowing through the first supply flow path 62.

[0033] As shown in FIG. 5, the warming device 64 includes a coil 71 , a container 72 , a heater 73 , a thermal 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 along the vertical direction. 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 liquid heat medium M1 (see FIG. 5) used to heat coiled tube 71. For example, container 72 includes a cylindrical portion extending along the vertical direction, 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 inside of the container 72 is filled with a heat medium M1 (see FIG. 5) in an amount sufficient to submerge the helical 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 so as to cover the outer surface of the container 72. In the warming 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 arranged 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 provided in contact with the heat medium M1. The ink temperature sensor 75 outputs a first detection signal including a signal value according to the temperature of the heat medium M1 with which it is in contact. 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 resin tube.

[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 (internal temperature) inside the housing of the image forming apparatus 100. 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 a supply path of the ink leading to the recording head 30. The 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 supply path in the ink supply direction D20 (see FIG. 4). The sub-ink tank 65 is provided in a specific section of the supply path from the heating position P1 to the recording head 30. The first pump 63 is provided upstream of the sub-ink tank 65 in the supply path in the supply direction D20, and supplies the ink heated by the heater 73 to the sub-ink tank 65. The 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 the same amount as 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 an example of a first ink flow path of 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 portion 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 discharged by the recording head 30. The ink receiving unit 81 is provided so as to be movable between a facing position facing the recording head 30 below the recording head 30 and a retracted position retracted horizontally from the facing position. The ink receiving unit 81 is moved to the retracted position when an image is formed on a sheet.

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

[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 container 84 contains the waste ink discharged by the recording head 30 .

[0052] The recovery flow path 82 forms a path for recovering the waste ink discharged 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 ink is heated by the heater 73 of the heating device 64 to a temperature suitable for forming an image.

[0054] Incidentally, in a conventional image forming apparatus, when 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, when the ink in the specific section is cold, the user has to wait a long time until image formation starts.

[0055] In contrast, in the image forming apparatus 100 according to the embodiment of the present invention, as described below, it is possible to reduce the waiting time of the user until the start of image formation.

[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, a DVD, or a 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 an application specific integrated circuit (ASIC). The operation control program may be a program for causing a plurality of 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 by PID control. For example, in the image forming apparatus 100, a switching element (not shown) capable of switching the conduction and interruption of the power supply path is provided on a power supply path between a power source (not shown) and the heater 73. The drive control unit 91 inputs a PWM signal having a duty ratio according to the difference between the first detected temperature and the target temperature to the switching element to control 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 most recent 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 an image. The normal state is a state in which power supply is being performed to the image forming unit 3 and the image forming apparatus 100 is able to form an image. For example, when the image forming apparatus 100 is in the normal state, the control unit 7 causes the image forming apparatus 100 to transition to the power saving state when a user operation is received to instruct transition to the power saving state, or when a predetermined time has elapsed since the last user operation was received. When the image forming apparatus 100 is in the power saving state, the control unit 7 causes the image forming apparatus 100 to transition to the normal state when a user operation is received. The power saving state is an example of a first state of the present invention. The normal state is an example of the second state. The first state of the present invention may include a state in which the power supply to the image forming apparatus 100 is shut 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 from the previous transition to the power saving state, that is, 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] Moreover, the acquisition processing unit 92 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. Note that the acquisition processing unit 92 may acquire the air temperature at the installation location of the image forming apparatus 100 by using a temperature sensor provided outside the housing of the image forming apparatus 100.

[0067] Then, the acquisition processing unit 92 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, in the image forming apparatus 100, 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 temperature that is predetermined within a printable temperature range. The printable temperature range is a temperature range of the ink that can form an image with an image quality that exceeds 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 temperature of the ink 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, when 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 temperature of the ink 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 include 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 value, 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 is reduced, 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 accommodated 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 accommodated 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 ink after heating by driving the first pump 63 can be calculated based on the following first value, second value, third value, and fourth value. The first value is a value indicating the amount of the ink stored in the sub-ink tank 65 after the second pump 67 sucks up the ink from the sub-ink tank 65 and before the first pump 63 supplies the ink to the sub-ink tank 65. The second value is a value indicating the amount of the ink supplied to the sub-ink tank 65 by the first pump 63. The third value is a value indicating the amount of the 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] That is, the amount of the ink heated by the heater 73 among the ink supplied to the sub-ink tank 65 by the first pump 63 is the amount obtained by subtracting the amount of the 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) from the amount of the ink supplied to the sub-ink tank 65 by the first pump 63 (the second value). In addition, the amount of the 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 amount obtained by adding the amount of the ink stored in the sub-ink tank 65 (the first value) after the second pump 67 sucks up the ink from the sub-ink tank 65 and before the first pump 63 supplies the ink to the sub-ink tank 65 to the amount of the 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). In addition, the temperature of the cooled ink is acquired by the acquisition processing unit 92. It is possible to calculate the temperature of the ink after heating (the specific temperature) at which the ink temperature in the sub-ink tank 65 becomes the optimal printing temperature by mixing the cooled ink and the heated ink.

[0080] For example, the setting processing unit 94 acquires the amount of ink stored in the sub-ink tank 65 before the ink is caused to flow by the flow processing unit 93, using a water level sensor (not shown) capable of detecting the water 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 ink stored. 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 ink stored (the first value), and the known second and third values ​​into a second calculation formula that is determined in advance.

[0081] Here, when 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 an excessive rise in temperature.

[0082] Table data indicating a correspondence relationship between the ink temperature acquired by the acquisition processing unit 92 and a temperature value used to set the target temperature may be stored in advance in the storage unit 6. The table data may define a correspondence relationship between the ink temperature acquired by the acquisition processing unit 92 and the temperature value such 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 less than 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] In addition, the target temperature may always be the optimum print 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 causes the operation display unit 5 to display a function setting screen used for switching between enabling and disabling the ink flow function 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 the ink consumption or shortening the waiting time until the start of image formation.

[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. indicate 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 one 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 previous 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 temperature of the ink 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 the first calculation formula.

[0090] <Step S12> In step S12, the control unit 7 determines whether or not the temperature of the ink acquired 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), the control unit 7 shifts the process to step S13. If the temperature of the ink is not less than the threshold value (No in S12), the control unit 7 shifts the process to step S21.

[0092] <Step S13> In step S13, the control unit 7 determines whether or not the ink flow function is enabled.

[0093] Here, when the control unit 7 determines that the ink flow function is enabled (Yes side of S13), the control unit 7 shifts the process to step S14. On the other hand, when the ink flow function is not enabled (No side of S13), the control unit 7 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 obtains the current amount of ink stored in the sub-ink tank 65 by using the water level sensor. The control unit 7 also obtains 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 obtained amount of ink stored. The control unit 7 also calculates the specific temperature by substituting the temperature of the ink (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. Then, 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, and if the calculated specific temperature exceeds the upper limit temperature, 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 portion 81 by driving the second pump 67, the control unit 7 uses the third pump 83 to cause the ink ejected to the ink receiving portion 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 side, 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 supply the ink heated by the heater 73 to the sub-ink tank 65 after reducing the amount of cooled ink stored in 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 by the heater 73 to the specific temperature or the upper limit temperature 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 prevent 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 the process of step S17, thereby making it possible to prevent the temperature of the ink in the sub-ink tank 65 from rising above the printable temperature by executing the process of step S17 for the second time.

[0104] <Step S18> In step S18, the control unit 7 determines whether or not 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 steps S16 and 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 side of S18), it ends the operation control process. On the other hand, when the heated ink has not reached the recording head 30 (No side of 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 less 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 user's waiting time until image formation starts.

[0110] [Other embodiments] The image forming apparatus 100 may 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 a third ink flow path of the present invention.

[0112] When the image forming apparatus 100 includes the circulation flow path 69, the flow processing unit 93 may execute 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 executed using the first pump 63, the second pump 67, the third pump 83, and an on-off valve capable of switching between permission and prohibition of 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 flow of the ink in the circulation flow path 69 is prohibited by the on-off valve. Moreover, the second flow process is executed 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 flow of the ink in the circulation flow path 69 is permitted by the on-off valve.

[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 makes it possible to replace the cooled ink in the circulation flow path 69 with the ink heated by the heater 73.

[0114] Moreover, the operation control process may include the processes of 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 the on-off valve is 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. In addition, the control unit 7 drives the first pump 63 after driving the second pump 67. As a result, the ink is sucked up from the ink container 61 side, 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. Therefore, 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. Also, 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 or not 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 steps S31 and S32 have been executed reaches the specific number of times.

[0119] Here, when the control unit 7 determines that the heated ink has reached the recording head 30 (Yes side of S33), it ends the operation control process. On the other hand, when the heated ink has not reached the recording head 30 (No side of 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 the variation in temperature of the ink in the circulation path.

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

[0122] [Notes on the invention] The following will provide an overview 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 to reach the ejection portion; a heater for heating the ink at a heating position upstream of the ejection portion in a flow direction of the ink in the supply path; a storage portion provided in a specific section of the supply path from the heating position to the ejection portion and for storing the ink; a drive control portion for controlling the drive of the heater based on a difference between a temperature of the ink at the heating position and a predetermined target temperature; an acquisition processing portion for acquiring a temperature of the ink in the specific section; a flow processing portion 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 portion is less than a predetermined threshold; and a setting processing portion for setting the target temperature based on the temperature of the ink acquired by the acquisition processing portion.

[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 from 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, further comprising a switching processing unit that switches between enabling and disabling an ink flow function performed by the flow processing unit in response to a user's operation, and the flow processing unit 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 when the temperature of the ink acquired by the acquisition processing unit is below the threshold value.

[0126] <Appendix 4> An image forming apparatus as described in any of Appendices 1 to 3, further comprising a third ink flow path which, together with the first ink flow path, forms a circulation path for the ink passing through the ejection section and the storage section, and the flow processing section performs a second flow process to cause the ink to flow along the circulation path after the ink warmed by the heater reaches the storage section by performing a first flow process to cause the ink to flow along the supply path and the recovery path.

[0127] <Appendix 5> an ink supply path provided upstream of the storage portion in the flow direction, the ink being heated by the heater and supplying the ink to the storage portion; and a second pump provided downstream of the storage portion in the flow direction, the ink supply path provided downstream of the storage portion in the flow direction, the ink being sucked up from the storage portion in an amount equal to an amount of the ink supplied by the first pump and supplying the ink to the ejection portion, wherein the flow processing portion uses the second pump to suck up the ink from the storage portion and then uses the first pump to supply the ink heated by the heater to the storage portion, and the setting processing portion sets the target temperature when the temperature of the ink acquired by the acquisition processing portion is less than the threshold value, by driving the first pump.

[0128] <Appendix 6> an ink supply path for the ink to reach the ejection portion; a heater for heating the ink at a heating position upstream of the ejection portion in a flow direction of the ink in the supply path; a storage portion provided in a specific section of the supply path from the heating position to the ejection portion for storing the ink; and a drive control portion for controlling the drive of the heater based on a difference between a temperature of the ink at the heating position and a predetermined target temperature, the operation control method including: an acquisition step for acquiring a temperature of the ink in the specific section; a flow step 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 step is less than a predetermined threshold; and a setting step for setting the target temperature based on the temperature of the ink acquired by the acquisition step. [Explanation of symbols]

[0129] 1 Case 2 Sheet transport section 3. Image forming section 4 Transport unit 5 Operation display section 6 Memory section 7 Control section 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 3rd 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; a storage section that is provided in a specific section of the supply path from the heating position to the ejection section and that stores the ink; a drive control unit that controls driving of the heater based on a difference between a temperature of the ink at the heating position and a preset target temperature; an acquisition processing unit that acquires the temperature of the ink in the specific section; a flow processing unit that, when the temperature of the ink acquired by the acquisition processing unit is less than a predetermined threshold value, causes the ink heated by the heater to flow along the supply path and the recovery path until the ink reaches the ejection unit; a setting processing unit that sets the target temperature based on the temperature of the ink acquired by the acquisition processing 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 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; 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. a first pump that is provided on the supply path upstream of the ink storage portion in the flow direction and that supplies the ink heated by the heater to the ink storage portion; a second pump that is provided on the supply path downstream of the storage portion in the flow direction and that sucks up the ink from the storage portion and supplies the ink to the ejection portion in an amount equal to an amount of the ink supplied by the first pump; Equipped with the flow processing section uses the second pump to suck up the ink from the storage section, and then uses the first pump to supply the ink heated by the heater to the storage section; the setting processing unit sets the target temperature such that, when the temperature of the ink acquired by the acquisition processing unit is less than the threshold value, the temperature of the ink in the storage unit becomes a predetermined specific value that is equal to or greater than the threshold value by driving the first pump.

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

6. an ink supply path for the ink to reach the ejection portion; a second ink flow path for recovering waste ink ejected by the ejection portion; a heater for heating the ink at a heating position upstream of the ejection portion in a flow direction of the ink in the supply path; a storage portion for storing the ink, the storage portion being provided in a specific section of the supply path from the heating position to the ejection portion; and a drive control portion for controlling the drive of the heater based on a difference between a temperature of the ink at the heating position and a preset target temperature, acquiring the temperature of the ink in the specific section; 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; a setting step of setting the target temperature based on the temperature of the ink acquired in the acquisition step; The motion control method includes:

Images