Image forming apparatus, ink supply method

Abstract

To provide an image forming apparatus and an ink supply method capable of suppressing the temperature of heated ink supplied to the storage section from falling below a target temperature. [Solution] The image forming apparatus includes a sub-ink tank 65 for storing the ink between the ink container 61 and the line head 30 in the ink supply path from the ink container 61 to the line head 30, a heating device 64 for heating the ink between the ink container 61 and the sub-ink tank 65 in the supply path, and a supply processing unit that supplies the ink from the ink container 61 to the sub-ink tank 65 at a supply rate based on the temperature of the installation location of the image forming apparatus.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus and an ink supply method.

Background Art

[0002] An inkjet type image forming apparatus including a discharge unit, a storage unit, and a reservoir unit is known. The discharge unit discharges ink. The storage unit stores the ink supplied to the discharge unit. The reservoir unit stores the ink between the storage unit and the discharge unit in the ink supply path from the storage unit to the discharge unit.

[0003] Also, an image forming apparatus including a heater that heats the ink to a target temperature between the storage unit and the reservoir unit in the supply path is known (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the image forming apparatus, when the ink stored in the storage unit is cooled, the temperature of the ink after being heated by the heater supplied to the reservoir unit may be lower than the target temperature.

[0006] An object of the present invention is to provide an image forming apparatus and an ink supply method capable of suppressing the temperature of the heated ink supplied to the reservoir unit from falling below the target temperature.

Means for Solving the Problems

[0007] An image forming apparatus according to one aspect of the present invention comprises a dispensing unit, a storage unit, a reservoir unit, a heater, a detection processing unit, and a supply processing unit. The dispensing unit dispenses ink. The storage unit stores the ink supplied to the dispensing unit. The reservoir unit stores the ink between the storage unit and the dispensing unit in the ink supply path from the storage unit to the dispensing unit. The heater heats the ink between the storage unit and the reservoir unit in the supply path. The detection processing unit detects the temperature of the installation location of the apparatus. The supply processing unit supplies the ink from the storage unit to the reservoir unit at a supply rate based on the detected temperature detected by the detection processing unit.

[0008] An ink supply method according to another aspect of the present invention is performed in an image forming apparatus comprising: an ink discharge unit for ejecting ink; a storage unit for storing the ink supplied to the discharge unit; a storage unit for storing the ink between the storage unit and the discharge unit in an ink supply path from the storage unit to the discharge unit; and a heater for heating the ink between the storage unit and the storage unit in the supply path, and includes a detection step and a supply step. In the detection step, the temperature of the installation location of the image forming apparatus is detected. In the supply step, the ink is supplied from the storage unit to the storage unit at a supply rate based on the detected temperature detected in the detection step. [Effects of the Invention]

[0009] According to the present invention, it is possible to suppress the temperature of the heated ink supplied to the storage unit from falling below the target temperature. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] Figure 2 shows the configuration of the image forming section and the transport unit of an image forming apparatus according to an embodiment of the present invention. [Figure 3]Figure 3 is a block diagram showing the system configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 4] Figure 4 shows the configuration of the ink supply unit and the ink recovery unit of an image forming apparatus according to an embodiment of the present invention. [Figure 5] Figure 5 shows the configuration of a heating device for an image forming apparatus according to an embodiment of the present invention. [Figure 6] Figure 6 is a flowchart showing an example of a first supply process performed in an image forming apparatus according to an embodiment of the present invention. [Figure 7] Figure 7 is a flowchart showing an example of a second supply process performed in an image forming apparatus according to an embodiment of the present invention. [Modes for carrying out the invention]

[0011] The embodiments of the present invention will be described below with reference to the attached drawings. Note that the following embodiments are merely examples of the present invention and do not limit the technical scope of the present invention.

[0012] [Configuration of the image forming apparatus 100] First, the configuration of the 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. Figure 2 is a plan view showing the configuration of the image forming unit 3 and the transport unit 4. Note that in Figure 1, the sheet transport path R11 is shown by a dashed line.

[0013] The image forming apparatus 100 is a printer capable of forming images on a sheet using an inkjet method. The present invention may also be applied to image forming apparatuses such as fax machines, copiers, and multifunction printers capable of forming images on a sheet using an inkjet method.

[0014] As shown in Figures 1 and 3, the image forming apparatus 100 comprises a housing 1, a sheet transport unit 2, an image forming unit 3, a transport unit 4, an operation display unit 5, a storage unit 6, a control unit 7, an ink supply unit 8, and an ink recovery unit 9.

[0015] The housing 1 houses each component of the image forming apparatus 100. A paper feed cassette 11 is detachably provided on the housing 1. A sheet on which an image is to be formed is housed in the paper feed cassette 11. A paper discharge tray 12 is provided on the outer surface of the housing 1. A sheet on which an image has been formed by the image forming unit 3 is discharged onto the paper discharge tray 12. Inside the housing 1, the sheet housed in the paper feed cassette 11 is conveyed along a sheet conveyance path R11 (see FIG. 1) that reaches the paper discharge tray 12 via the image forming position by the image forming unit 3.

[0016] The sheet conveyance unit 2 conveys the sheet housed in the paper feed cassette 11 along the sheet conveyance path R11 (see FIG. 1). As shown in FIG. 1, the sheet conveyance unit 2 includes a pickup roller 21 and a plurality of conveyance rollers 22. The pickup roller 21 picks up the uppermost sheet in the stack of sheets housed in the paper feed cassette 11 and sends out the sheet onto the sheet conveyance path R11. The plurality of conveyance rollers 22 are arranged side by side along the sheet conveyance path R11. Each of the conveyance rollers 22 conveys the sheet along the sheet conveyance path R11. Each of the conveyance rollers 22 conveys the sheet in the conveyance direction D11 (see FIG. 1) from the paper feed cassette 11 toward the paper discharge tray 12.

[0017] The image forming unit 3 forms an image based on image data on the sheet supplied from the sheet conveyance unit 2. As shown in FIG. 1, the image forming unit 3 includes four line heads 30 (line heads 31 to 34) and a head frame 35.

[0018] As shown in FIG. 2, each of the line heads 30 is long in the width direction D12 orthogonal to the conveyance direction D11. Specifically, each of the line heads 30 has a length corresponding to the width of the largest-size sheet that can be housed in the paper feed cassette 11 in the width direction D12. The four line heads 30 are arranged side by side at equal intervals along the conveyance direction D11.

[0019] As shown in FIG. 2, each line head 30 has a plurality of recording heads 36. The recording heads 36 eject ink toward a sheet conveyed by the conveying unit 4. Specifically, a large number of nozzles 37 (see FIG. 2) used for ejecting the ink are provided on the surface of the recording head 36 facing the sheet.

[0020] Each line head 30 ejects the ink. Specifically, the line head 31 ejects the black ink. Also, the line head 32 ejects the cyan ink. Also, the line head 33 ejects the magenta ink. Also, the line head 34 ejects the yellow ink. The line head 30 is an example of the ejection unit of the present invention.

[0021] In the present embodiment, in the line head 31, three recording heads 36 are arranged in a staggered pattern along the width direction D12. Also, in each of the other line heads 32 to 34, three recording heads 36 are arranged in a staggered pattern along the width direction D12, similarly to the line head 31. Note that FIG. 2 shows a state in which the image forming unit 3 is viewed from above in FIG. 1.

[0022] The head frame 35 supports the four line heads 30. The head frame 35 is supported by the housing 1. Note that the number of line heads 30 provided in the image forming unit 3 may be one or more. Also, the number of recording heads 36 provided in each line head 30 does not have to be limited to three.

[0023] As shown in Figure 1, the transport unit 4 is positioned below the four line heads 30. The transport unit 4 transports the sheets while keeping them facing the line heads 30. For example, each time the line heads 30 dispense the ink, the transport unit 4 transports a predetermined amount of sheets. The transport unit 4 also stops transporting the sheets while the line heads 30 are dispensing the ink. As shown in Figure 1, the transport unit 4 comprises a transport belt 41 on which the sheets are 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 them. The gap between the transport belt 41 and the recording head 36 is adjusted so that the gap between the surface of the sheet and the recording head 36 during image formation is a predetermined distance (e.g., 1 mm).

[0024] The first tension roller 42 is rotationally driven by a rotational driving force supplied from a motor (not shown). This causes the conveyor belt 41 to rotate in a direction that allows the sheet to be conveyed in the conveying direction D11 (see Figure 1). The conveying unit 4 is also equipped with a suction unit (not shown) that draws in air through numerous through holes formed in the conveyor belt 41 in order to attract the sheet to the conveyor belt 41. In addition, a pressure roller 46 is provided above the first tension roller 42 to press the sheet against the conveyor belt 41 for conveyance.

[0025] The operation display unit 5 is the user interface of the image forming apparatus 100. The operation display unit 5 comprises 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.

[0026] The storage unit 6 is a non-volatile storage device. For example, the storage unit 6 is a non-volatile memory such as flash memory. The storage unit 6 may also be an SSD (Solid State Drive) or an HDD (Hard Disk Drive).

[0027] The control unit 7 comprehensively controls the image forming apparatus 100. As shown in Figure 3, the control unit 7 comprises a CPU 51, a ROM 52, and a RAM 53. The CPU 51 is a processor that performs various arithmetic operations. The ROM 52 is a non-volatile memory device in which information such as control programs for causing the CPU 51 to perform various operations is pre-stored. The RAM 53 is a volatile or non-volatile memory device used as a temporary storage memory (work area) for the various operations performed by the CPU 51. The CPU 51 comprehensively controls the image forming apparatus 100 by executing various control programs pre-stored in the ROM 52. Note that the control unit 7 may be a separate control unit from the main control unit that comprehensively controls the image forming apparatus 100. Furthermore, the control unit 7 may be composed of electronic circuits such as an integrated circuit (ASIC).

[0028] [Configuration of the ink supply unit 8 and the 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 corresponding to the line head 31. Figure 5 is a cross-sectional view showing the configuration of the heating device 64 corresponding to the line head 31. In Figure 4, the first supply channel 62, the second supply channel 66, and the recovery channel 82 are shown with thick lines.

[0029] The ink supply unit 8 supplies the ink to the line head 30. An ink supply unit 8 is provided for each line head 30. The configuration of the four ink supply units 8 corresponding to the four line heads 30 is the same, except that the color of the ink supplied differs.

[0030] As shown in Figures 3 and 4, the ink supply unit 8 includes an ink container 61, a first supply channel 62, a first pump 63, a heating device 64, a sub-ink tank 65, a second supply channel 66, a second pump 67, and an external temperature sensor 68.

[0031] The ink container 61 contains the ink supplied to the line head 30. For example, the ink is an aqueous ink with water as the main solvent. However, the ink may also be a non-aqueous ink with an organic solvent as the main solvent. The ink container 61 is an example of a storage unit of the present invention.

[0032] The first supply channel 62 is an ink channel provided between the ink container 61 and the sub-ink tank 65. The first supply channel 62 is formed from a flexible material. For example, the first supply channel 62 is a resin tube.

[0033] The first pump 63 forms part of the first supply channel 62. The first pump 63 causes the ink in the first supply channel 62 to flow in a first flow direction D21 (see Figure 4) toward the line head 30. For example, the first pump 63 is a syringe pump.

[0034] The heating device 64 forms part of the first supply channel 62. The heating device 64 heats the ink flowing through the first supply channel 62.

[0035] As shown in Figure 5, the heating device 64 comprises a coiled tube 71, a container 72, a heater 73, an insulating material 74, and an ink temperature sensor 75.

[0036] The serpentine tube 71 is a spirally formed tube. The serpentine tube 71 is positioned so that its spiral axis is aligned with the vertical direction. For example, the serpentine tube 71 is formed by processing a straight metal pipe into a spiral shape. The serpentine tube 71 forms part of the first supply channel 62.

[0037] The container 72 houses the bellows 71 and the liquid heat transfer medium M1 (see Figure 5) used to heat the bellows 71. For example, the container 72 includes a cylindrical portion extending vertically, a disc-shaped bottom portion that closes the lower end of the cylindrical portion, and a disc-shaped top portion that closes the upper end of the cylindrical portion.

[0038] The inside of the container 72 is filled with a heat transfer medium M1 (see Figure 5) in an amount sufficient to submerge the spirally formed spiral portion contained in the serrated tube 71. For example, the heat transfer medium M1 is water. Note that the heat transfer medium M1 is not limited to water; it may also be a fluid such as oil.

[0039] 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 element and a metal sheet, such as aluminum, that covers the heating element. The heater 73 is provided so as to cover the outer surface of the container 72. In the heating device 64, the heat transfer medium M1 contained in the container 72 is heated by the heating element 73 as the container 72 is heated. As a result, the ink flowing inside the spiral portion placed in the heat transfer medium M1 is heated to the same temperature as the heat transfer medium M1.

[0040] The insulating material 74 is provided so as to cover the outer surface of the container 72. The heater 73 is provided between the container 72 and the insulating material 74. For example, the insulating material 74 is provided so as to cover the entire outer surface of the container 72.

[0041] 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 in contact with the heat medium M1. The ink temperature sensor 75 outputs a first detection signal that includes a signal value corresponding to the temperature of the heat medium M1 it is in contact with. The first detection signal output from the ink temperature sensor 75 is input to the control unit 7. Based on the first detection signal input from the ink temperature sensor 75, the control unit 7 controls the drive of the heater 73 so that the temperature of the heat medium M1 reaches a predetermined target temperature.

[0042] The heating device 64 may be configured to heat the ink without using a heat transfer medium M1. For example, the heating device 64 may be configured to include a metal ink flow path and a heater 73 that directly heats the flow path.

[0043] 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 line head 30.

[0044] The second supply channel 66 is an ink channel provided between the sub-ink tank 65 and the line head 30. The second supply channel 66 is made of a flexible material. For example, the second supply channel 66 is a resin tube.

[0045] The second pump 67 forms part of the second supply channel 66. The second pump 67 causes the ink in the second supply channel 66 to flow in the second flow direction D22 (see Figure 4). For example, the second pump 67 is a syringe pump.

[0046] The external temperature sensor 68 detects the ambient temperature outside the housing 1. The external temperature sensor 68 is located outside the housing 1. The external temperature sensor 68 outputs a second detection signal that includes a signal value corresponding to the ambient temperature outside the housing 1. The second detection signal output from the external temperature sensor 68 is input to the control unit 7.

[0047] The first supply channel 62 and the second supply channel 66 form the ink supply path from the ink container 61 to the line head 30. The heater 73 of the heating device 64 heats the ink between the ink container 61 and the sub-ink tank 65 in the supply path. The sub-ink tank 65 stores the ink between the ink container 61 and the line head 30 in the supply path. The sub-ink tank 65 is an example of a storage unit of the present invention.

[0048] The ink recovery unit 9 recovers the ink (waste ink) ejected by the line head 30. An ink recovery unit 9 is provided for each line head 30. The configuration of the four ink recovery units 9 corresponding to the four line heads 30 is the same, except that the color of the recovered ink differs.

[0049] As shown in Figures 3 and 4, the ink recovery unit 9 includes an ink receiving section 81, a recovery channel 82, a third pump 83, and a waste ink storage section 84.

[0050] The ink receiving section 81 receives the waste ink ejected by the line head 30. The ink receiving section 81 is provided so as to be movable between a position facing the line head 30 below the line head 30 and a retracted position horizontally retracted from the facing position. The ink receiving section 81 is moved to the retracted position when an image is formed on the sheet.

[0051] The recovery channel 82 is an ink channel provided between the ink receiving section 81 and the waste ink storage section 84. The recovery channel 82 is made of a flexible material. For example, the recovery channel 82 is a resin tube.

[0052] The third pump 83 forms part of the recovery channel 82. The third pump 83 causes the waste ink in the recovery channel 82 to flow in the third flow direction D23 (see Figure 4). For example, the third pump 83 is a syringe pump.

[0053] The waste ink storage section 84 stores the waste ink ejected by the line head 30.

[0054] Incidentally, in conventional image forming apparatuses, if the ink contained in the ink container 61 is cold, the temperature of the ink after heating by the heater 73 supplied to the sub-ink tank 65 may fall below the target temperature.

[0055] In contrast, the image forming apparatus 100 according to an embodiment of the present invention can suppress the temperature of the heated ink supplied to the sub-ink tank 65 from falling below the target temperature, as will be explained below.

[0056] [Configuration of Control Unit 7] Next, the configuration of the control unit 7 will be explained in more detail with reference to Figure 3.

[0057] As shown in Figure 3, the control unit 7 includes a detection processing unit 91, a supply processing unit 92, a discharge processing unit 93, a notification processing unit 94, a formation processing unit 95, and a delay processing unit 96.

[0058] Specifically, the ROM 52 of the control unit 7 contains pre-stored operation control programs for the CPU 51 to function as each of the aforementioned processing units. The CPU 51 then functions as each of the aforementioned processing units by executing the operation control programs stored in the ROM 52.

[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 storage unit 6. Furthermore, some or all of the above-described processing units may be composed of electronic circuits such as integrated circuits (ASICs). Also, the operation control program may be a program that causes multiple processors to function as processing units included in the control unit 7.

[0060] The detection processing unit 91 detects the temperature of the installation location of the image forming apparatus 100.

[0061] For example, the detection processing unit 91 detects the external temperature using the external temperature sensor 68. That is, the detection processing unit 91 acquires the external temperature corresponding to the first detection signal output from the external temperature sensor 68 as the temperature of the installation location of the image forming apparatus 100. Alternatively, the detection processing unit 91 may detect the temperature inside the housing 1 as the temperature of the installation location of the image forming apparatus 100.

[0062] The supply processing unit 92 supplies the ink from the ink container 61 to the sub-ink tank 65 at a supply rate based on the detected temperature detected by the detection processing unit 91.

[0063] Specifically, if the detected temperature is above a predetermined reference temperature, the supply processing unit 92 supplies the ink from the ink container 61 to the sub-ink tank 65 at a predetermined first supply speed. If the detected temperature is below the reference temperature, the supply processing unit 92 supplies the ink from the ink container 61 to the sub-ink tank 65 at a second supply speed that is slower than the first supply speed.

[0064] For example, if the detected temperature is below the reference temperature, the supply processing unit 92 supplies the ink from the ink container 61 to the sub-ink tank 65 at the second supply rate based on the detected temperature.

[0065] For example, the first supply speed is the same as the rate at which the ink of the color of the image is consumed when a monochrome image with a print density of 100 percent is formed on the sheet.

[0066] Furthermore, the reference temperature is set such that, if the temperature of the ink in the ink container 61 is below the reference temperature, the temperature of the ink that has passed through the heating device 64 at the first supply speed will be below the target temperature, and if the temperature of the ink in the ink container 61 is above the reference temperature, the temperature of the ink that has passed through the heating device 64 at the first supply speed will be the target temperature.

[0067] Furthermore, the second supply rate is calculated according to the following formula (1). In formula (1), "V2" represents the second supply rate (mL / sec). In formula (1), "V1" represents the first supply rate (mL / sec). In formula (1), "Tc" represents the detection temperature (°C). In formula (1), "T1" represents the reference temperature (°C).

[0068] V2 = V1 × Tc ÷ T1 ... (1)

[0069] The supply processing unit 92 drives the first pump 63 so that the ink is supplied from the ink container 61 to the sub-ink tank 65 at the supply speed.

[0070] Furthermore, a first table data showing the correspondence between the detected temperature and the second supply speed may be stored in the storage unit 6 in advance. In the first table data, the correspondence between the detected temperature and the second supply speed should be defined such that the lower the detected temperature, the slower the second supply speed becomes. If the first table data is stored in the storage unit 6, the second supply speed should be obtained using the first table data.

[0071] Furthermore, the second supply rate may be a predetermined constant value.

[0072] Furthermore, the supply processing unit 92 may acquire the first supply rate based on the detected temperature if the detected temperature is equal to or greater than the reference temperature. In other words, the first supply rate does not have to be a predetermined constant value.

[0073] The discharge processing unit 93 performs a discharge process to discharge the ink stored in the sub-ink tank 65.

[0074] For example, the discharge processing unit 93 executes the discharge process when the power to the image forming apparatus 100 is turned on. The discharge processing unit 93 also executes the discharge process when the operating mode of the image forming apparatus 100 transitions from a power-saving mode, which consumes less power than the normal mode, to the normal mode. The discharge processing unit 93 may also execute the discharge process when a predetermined operation is received in the operation display unit 5.

[0075] For example, in the discharge process, the second pump 67 is used to discharge the ink from the line head 30 to the ink receiving section 81 until the amount of ink remaining in the sub-ink tank 65 is depleted. In addition, in the discharge process, the third pump 83 is used to send the waste ink discharged to the ink receiving section 81 to the waste ink storage section 84.

[0076] Here, after the discharge process is performed, the supply processing unit 92 supplies the ink from the ink container 61 to the sub-ink tank 65 until the remaining amount of ink in the sub-ink tank 65 reaches a predetermined second amount.

[0077] For example, the second amount is the same as the amount of ink remaining in the sub-ink tank 65 when the sub-ink tank 65 is full.

[0078] For example, the ink supply unit 8 includes an ink level detection sensor (not shown) capable of detecting the remaining amount of ink in the sub-ink tank 65.

[0079] The supply processing unit 92 supplies the ink from the ink container 61 to the sub-ink tank 65 until the amount of ink remaining in the sub-ink tank 65, as detected by the remaining amount detection sensor, reaches the second amount.

[0080] The notification processing unit 94 notifies the supplier if, when the supply processing unit 92 supplies the ink after the discharge process has been executed, the supply of the ink does not end before the elapsed time from the start of the supply of the ink by the supply processing unit 92 exceeds the allowable time corresponding to the supply speed.

[0081] For example, the allowable time is calculated according to the following formula (2). In formula (2), "A" represents the allowable time (sec). In formula (2), "B" represents the second volume (mL). In formula (2), "V" represents the supply rate (mL / sec).

[0082] A = B ÷ V ... (2)

[0083] For example, if the supply of ink by the supply processing unit 92 does not end before the elapsed time from the start of ink supply exceeds the allowable time, the notification processing unit 94 will display a message on the operation display unit 5 indicating that there is a problem with the ink supply unit 8.

[0084] Furthermore, a second table data showing the correspondence between the supply speed and the allowable time may be stored in the storage unit 6 in advance. In the second table data, the correspondence between the supply speed and the allowable time should be defined such that the slower the supply speed, the longer the allowable time. If the second table data is stored in the storage unit 6, the allowable time should be obtained using the second table data.

[0085] The forming unit 95 performs a forming process to form an image on the sheet using the line head 30.

[0086] Here, the supply processing unit 92 supplies the ink from the ink container 61 to the sub-ink tank 65 if the amount of ink remaining in the sub-ink tank 65 is less than a predetermined first amount during the execution of the forming process.

[0087] The first quantity is less than the second quantity.

[0088] For example, if the amount of ink remaining in the sub-ink tank 65 detected by the remaining amount detection sensor during the formation process is less than the first amount, the supply processing unit 92 supplies the ink from the ink container 61 to the sub-ink tank 65 until the amount reaches a third amount, which is greater than the first amount and less than the second amount.

[0089] The delay processing unit 96 delays the formation of an image when the printing rate of the image formed on the sheet during the supply of the ink at the second supply speed by the supply processing unit 92 exceeds a threshold corresponding to the second supply speed.

[0090] For example, the threshold is calculated according to the following formula (3). In formula (3), "C" represents the threshold (%). In formula (3), "V2" represents the second supply rate (mL / sec). In formula (3), "V1" represents the first supply rate (mL / sec).

[0091] C = (V2 ÷ V1) × 100 ... (3)

[0092] For example, if the delay processing unit 96 delays the formation of an image formed on the sheet while the supply processing unit 92 is supplying the ink at the second supply speed, the delay processing unit 96 delays the formation of the image until the supply of the ink by the supply processing unit 92 is completed. The print rate of the image formed on the sheet can be obtained based on the image data used to form the image.

[0093] Furthermore, a third table data showing the correspondence between the second supply speed and the threshold value may be stored in the storage unit 6 in advance. In the third table data, the correspondence between the second supply speed and the threshold value should be defined such that the slower the second supply speed, the smaller the threshold value becomes. If the third table data is stored in the storage unit 6, the threshold value should be obtained using the third table data.

[0094] The ink supply method of the present invention will be described below, along with an example of the procedure for each process performed by the control unit 7.

[0095] [First supply process] The following describes an example of the procedure for the first supply process performed by the control unit 7 in the image forming apparatus 100, with reference to Figure 6. Here, steps S11, S12, etc., represent the numbers of the processing procedures (steps) performed by the control unit 7. The first supply process is performed when the power to the image forming apparatus 100 is turned on. The first supply process is also performed when the operating mode of the image forming apparatus 100 transitions from the power-saving mode to the normal mode.

[0096] The first supply process is performed for each ink supply unit 8 corresponding to each line head 30.

[0097] <Step S11> First, in step S11, the control unit 7 drives the heater 73.

[0098] Specifically, the control unit 7 controls the operation of the heater 73 based on the first detection signal input from the ink temperature sensor 75, so that the temperature of the heat transfer medium M1 reaches the target temperature.

[0099] <Step S12> In step S12, the control unit 7 executes the discharge process. The process in step S12 is performed by the discharge processing unit 93 of the control unit 7.

[0100] <Step S13> In step S13, the control unit 7 detects the temperature of the installation location of the image forming apparatus 100. The process in step S13 is an example of the detection steps of the present invention and is performed by the detection processing unit 91 of the control unit 7.

[0101] <Step S14> In step S14, the control unit 7 determines whether the detected temperature detected by the processing in step S13 is equal to or greater than the reference temperature.

[0102] Here, if the control unit 7 determines that the detected temperature is equal to or greater than the reference temperature (Yes side of S14), it proceeds to step S15. If the detected temperature is not equal to or greater than the reference temperature (No side of S14), the control unit 7 proceeds to step S21.

[0103] <Step S15> In step S15, the control unit 7 starts supplying the ink from the ink container 61 to the sub-ink tank 65 at the first supply speed. The process in step S15 is an example of the supply step of the present invention and is performed by the supply processing unit 92 of the control unit 7.

[0104] <Step S16> In step S16, the control unit 7 determines whether the remaining amount of ink in the sub-ink tank 65 has reached the second amount.

[0105] Here, if the control unit 7 determines that the remaining amount of ink in the sub-ink tank 65 has reached the second amount (Yes side of S16), it terminates the supply of ink to the sub-ink tank 65 and ends the first supply process. If the remaining amount of ink in the sub-ink tank 65 has not reached the second amount (No side of S16), the control unit 7 moves the process to step S17.

[0106] <Step S17> In step S17, the control unit 7 determines whether the elapsed time since the execution of the process in step S15 exceeds the allowable time corresponding to the first supply rate.

[0107] Here, if the control unit 7 determines that the elapsed time since the execution of the process in step S15 has exceeded the allowable time corresponding to the first supply speed (Yes side of S17), it moves the process to step S18. If the elapsed time since the execution of the process in step S15 has not exceeded the allowable time corresponding to the first supply speed (No side of S17), the control unit 7 moves the process to step S16.

[0108] <Step S18> In step S18, the control unit 7 terminates the supply of ink to the sub-ink tank 65 and notifies that the supply of ink did not end before the elapsed time from the start of ink supply exceeded the allowable time. The process in step S18 is performed by the notification processing unit 94 of the control unit 7.

[0109] For example, the control unit 7 causes the operation display unit 5 to display a message indicating that there is an abnormality in the ink supply unit 8.

[0110] <Step S21> In step S21, the control unit 7 starts supplying the ink from the ink container 61 to the sub-ink tank 65 at the second supply rate. The process in step S21 is an example of the supply step of the present invention and is performed by the supply processing unit 92 of the control unit 7.

[0111] <Step S22> In step S22, the control unit 7 determines whether the remaining amount of ink in the sub-ink tank 65 has reached the second amount.

[0112] Here, if the control unit 7 determines that the remaining amount of ink in the sub-ink tank 65 has reached the second amount (Yes side of S22), it terminates the supply of ink to the sub-ink tank 65 and ends the first supply process. If the remaining amount of ink in the sub-ink tank 65 has not reached the second amount (No side of S22), the control unit 7 moves the process to step S23.

[0113] <Step S23> In step S23, the control unit 7 determines whether the elapsed time since the execution of the process in step S21 exceeds the allowable time corresponding to the second supply rate.

[0114] Here, if the control unit 7 determines that the elapsed time since the execution of the process in step S21 has exceeded the allowable time corresponding to the second supply speed (Yes side of S23), it proceeds to step S24. If the elapsed time since the execution of the process in step S21 has not exceeded the allowable time corresponding to the second supply speed (No side of S23), the control unit 7 proceeds to step S22.

[0115] <Step S24> In step S24, the control unit 7 terminates the supply of ink to the sub-ink tank 65 and notifies that the supply of ink did not end before the elapsed time from the start of ink supply exceeded the allowable time. The processing in step S24 is performed by the notification processing unit 94 of the control unit 7.

[0116] For example, the control unit 7 causes the operation display unit 5 to display a message indicating that there is an abnormality in the ink supply unit 8.

[0117] [Second supply processing] Next, with reference to Figure 7, an example of the procedure for the second supply process executed by the control unit 7 in the image forming apparatus 100 will be described. The second supply process is executed together with the forming process when an instruction to execute the forming process is input.

[0118] The second supply process is performed for each ink supply unit 8 corresponding to each line head 30. Below, the second supply process corresponding to line head 31 will be described, out of the four second supply processes.

[0119] <Step S31> First, in step S31, the control unit 7 detects the temperature of the installation location of the image forming apparatus 100. The process in step S31 is an example of the detection steps of the present invention and is performed by the detection processing unit 91 of the control unit 7.

[0120] <Step S32> In step S32, the control unit 7 determines whether the detected temperature detected by the processing in step S31 is equal to or greater than the reference temperature.

[0121] Here, if the control unit 7 determines that the detected temperature is equal to or greater than the reference temperature (Yes side of S32), it proceeds to step S33. If the detected temperature is not equal to or greater than the reference temperature (No side of S32), the control unit 7 proceeds to step S41.

[0122] Furthermore, the temperature of the ink in the ink container 61 gradually rises from the temperature of the installation location of the image forming apparatus 100 as time passes from the start of the first supply process. Therefore, even if the control unit 7 determines in step S32 that the detected temperature is below the reference temperature, if the elapsed time from the start of the first supply process exceeds a predetermined time, it may proceed to step S33.

[0123] <Step S33> In step S33, the control unit 7 determines whether the forming process has been completed.

[0124] If the control unit 7 determines that the forming process is complete (Yes in S33), it terminates the second supply process. If the forming process is not complete (No in S33), the control unit 7 proceeds to step S34.

[0125] <Step S34> In step S34, the control unit 7 determines whether the remaining amount of ink in the sub-ink tank 65 is less than the first amount.

[0126] Here, if the control unit 7 determines that the remaining amount of ink in the sub-ink tank 65 is less than the first amount (Yes side of S34), it proceeds to step S35. If the remaining amount of ink in the sub-ink tank 65 is not less than the first amount (No side of S34), the control unit 7 proceeds to step S33.

[0127] <Step S35> In step S35, the control unit 7 supplies the ink from the ink container 61 to the sub-ink tank 65 at the first supply speed. The process in step S35 is an example of the supply step of the present invention and is performed by the supply processing unit 92 of the control unit 7.

[0128] Specifically, the control unit 7 supplies the ink from the ink container 61 to the sub-ink tank 65 until the remaining amount of ink in the sub-ink tank 65 reaches the third amount.

[0129] <Step S41> In step S41, the control unit 7 determines whether the forming process has been completed.

[0130] If the control unit 7 determines that the forming process is complete (Yes side of S41), it terminates the second supply process. If the forming process is not complete (No side of S41), the control unit 7 proceeds to step S42.

[0131] <Step S42> In step S42, the control unit 7 determines whether the remaining amount of ink in the sub-ink tank 65 is less than the first amount.

[0132] Here, if the control unit 7 determines that the remaining amount of ink in the sub-ink tank 65 is less than the first amount (Yes side of S42), it proceeds to step S43. If the remaining amount of ink in the sub-ink tank 65 is not less than the first amount (No side of S42), the control unit 7 proceeds to step S41.

[0133] <Step S43> In step S43, the control unit 7 supplies the ink from the ink container 61 to the sub-ink tank 65 at the second supply speed. The process in step S43 is an example of the supply step of the present invention and is performed by the supply processing unit 92 of the control unit 7.

[0134] Specifically, the control unit 7 supplies the ink from the ink container 61 to the sub-ink tank 65 until the remaining amount of ink in the sub-ink tank 65 reaches the third amount.

[0135] Here, the control unit 7 delays the formation of the black image if the printing rate of the black image formed on the sheet during the ink supply process in step S43 exceeds the threshold corresponding to the second supply speed. This makes it possible to avoid an excessive decrease in the amount of ink remaining in the sub-ink tank 65 when the ink consumption rate exceeds the second supply speed.

[0136] In this way, the image forming apparatus 100 controls the speed at which the ink passes through the heating device 64 based on the temperature detection result of the installation location of the image forming apparatus 100. As a result, the lower the temperature of the ink contained in the ink container 61, the slower the speed at which the ink passes through the heating device 64 can be made, thereby increasing the time the ink is heated. Therefore, it is possible to prevent the temperature of the heated ink supplied to the sub-ink tank 65 from falling below the target temperature.

[0137] [Notes on the invention] The following is an overview of the invention extracted from the above-described embodiments. Note that each configuration and processing function described below can be selected and combined as desired.

[0138] <Note 1> An image forming apparatus comprising: an ink ejection unit for ejecting ink; a storage unit for storing the ink supplied to the ejection unit; a storage unit for storing the ink between the storage unit and the ejection unit in the ink supply path from the storage unit to the ejection unit; a heater for heating the ink between the storage unit and the storage unit in the supply path; a detection processing unit for detecting the temperature of the installation location of the apparatus; and a supply processing unit for supplying the ink from the storage unit to the storage unit at a supply rate based on the detected temperature detected by the detection processing unit.

[0139] <Note 2> The image forming apparatus according to Appendix 1, wherein the supply processing unit supplies the ink from the storage unit to the storage unit at a predetermined first supply speed when the detected temperature is above a predetermined reference temperature, and supplies the ink from the storage unit to the storage unit at a second supply speed slower than the first supply speed when the detected temperature is below the reference temperature.

[0140] <Note 3> The image forming apparatus according to Appendix 2, wherein the supply processing unit supplies the ink from the storage unit to the storage unit at a second supply rate based on the detected temperature when the detected temperature is less than the reference temperature.

[0141] <Note 4> The image forming apparatus according to Appendix 2 or 3, comprising a forming processing unit that performs a forming process to form an image on a sheet using the discharge unit, the supply processing unit supplies the ink from the storage unit to the storage unit when the remaining amount of the ink in the storage unit is less than a predetermined first amount during the execution of the forming process, and the image forming apparatus comprising a delay processing unit that delays the formation of the image when the printing rate of the image formed on the sheet during the supply of the ink at the second supply speed by the supply processing unit exceeds a threshold corresponding to the second supply speed.

[0142] <Note 5> The image forming apparatus according to any one of the appendices 1 to 4, comprising: a discharge processing unit that performs a discharge process for discharging the ink stored in the storage unit; a supply processing unit that, after the discharge process is performed, supplies the ink from the storage unit to the storage unit until the remaining amount of ink in the storage unit reaches a predetermined second amount; and a notification processing unit that notifies the image forming apparatus if the supply of the ink does not end before the elapsed time from the start of the supply of the ink by the supply processing unit exceeds an allowable time corresponding to the supply speed.

[0143] <Note 6> An ink supply method performed in an image forming apparatus comprising: an ink ejection unit for ejecting ink; a storage unit for storing the ink supplied to the ejection unit; a storage unit for storing the ink between the storage unit and the ejection unit in an ink supply path from the storage unit to the ejection unit; and a heater for heating the ink between the storage unit and the storage unit in the supply path, the method comprising: a detection step for detecting the temperature of the installation location of the image forming apparatus; and a supply step for supplying the ink from the storage unit to the storage unit at a supply rate based on the detected temperature detected by the detection step. [Explanation of Symbols]

[0144] 1 cabinet 2 Sheet transport section 3 Image forming unit 4. Conveyor Unit 5 Operation display section 6 Memory section 7 Control Unit 8. Ink supply unit 9. Ink recovery unit 30 line heads 61 Ink Containers 62 First supply channel 63 Pump No. 1 64 Warming device 65 Sub Ink Tanks 66 Second supply channel 67. Pump No. 2 68 External temperature sensor 73 Heater 75 Ink temperature sensor 91 Detection Processing Unit 92 Supply Processing Unit 93 Discharge Processing Unit 94 Notification Processing Unit 95 Forming Processing Section 96 Delay Processing Unit 100 Image forming apparatus

Claims

1. The ejection section that ejects ink, A storage section for storing the ink supplied to the discharge section, A storage section for storing the ink between the storage section and the discharge section in the ink supply path from the storage section to the discharge section, A heater for heating the ink is provided between the containment section and the storage section in the supply path. A detection processing unit that detects the temperature of the installation location of the device, A supply processing unit that supplies the ink from the containment unit to the storage unit at a supply rate based on the detected temperature detected by the detection processing unit, An image forming apparatus equipped with the following features.

2. The supply processing unit supplies the ink from the storage unit to the storage unit at a predetermined first supply rate if the detected temperature is above a predetermined reference temperature, and supplies the ink from the storage unit to the storage unit at a second supply rate slower than the first supply rate if the detected temperature is below the reference temperature. The image forming apparatus according to claim 1.

3. The supply processing unit supplies the ink from the storage unit to the storage unit at the second supply rate based on the detected temperature if the detected temperature is less than the reference temperature. The image forming apparatus according to claim 2.

4. The system includes a forming processing unit that performs a forming process to form an image on a sheet using the aforementioned dispensing unit, The supply processing unit supplies ink from the storage unit to the storage unit when the remaining amount of ink in the storage unit is less than a predetermined first amount during the execution of the forming process. The image forming apparatus includes a delay processing unit that delays the formation of an image when the printing rate of an image formed on the sheet during the supply of ink at the second supply speed by the supply processing unit exceeds a threshold corresponding to the second supply speed. The image forming apparatus according to claim 2.

5. The system includes a discharge processing unit that performs a discharge process to discharge the ink stored in the storage unit, The supply processing unit, after the discharge process is performed, supplies the ink from the storage unit to the storage unit until the remaining amount of ink in the storage unit reaches a predetermined second amount. The image forming apparatus includes a notification processing unit that notifies the user if the supply of ink does not end before the elapsed time from the start of ink supply by the supply processing unit exceeds an allowable time corresponding to the supply speed. The image forming apparatus according to claim 1.

6. An ink supply method performed in an image forming apparatus comprising: an ink ejection unit for ejecting ink; a storage unit for storing the ink supplied to the ejection unit; a storage unit for storing the ink between the storage unit and the ejection unit in the ink supply path from the storage unit to the ejection unit; and a heater for heating the ink between the storage unit and the storage unit in the supply path, wherein A detection step for detecting the temperature of the installation location of the image forming apparatus, A supply step comprising supplying the ink from the containment section to the storage section at a supply rate based on the detected temperature detected by the detection step, An ink supply method including [details omitted].

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