Image forming apparatus and liquid consumption calculation method

Abstract

The present invention provides an image forming apparatus capable of suitably calculating the amount of liquid consumed during liquid replenishment. [Solution] The image forming apparatus 1 comprises a recording head 30 that forms an image on a recording medium by discharging liquid 2, and a plurality of storage units 11, 12 in which the liquid 2 is stored. The image forming apparatus 1 also comprises a supply unit 20 that supplies the stored liquid 2 to the recording head 30, and a plurality of liquid volume detection units 61, 62 that detect the amount of liquid stored in the plurality of storage units 11, 12, respectively. The image forming apparatus 1 also comprises a control unit 8 that controls the supply unit 20. The control unit 8 calculates the amount of liquid 2 consumed based on the amount of liquid 2 detected by the liquid volume detection unit 62 in the storage units 12 other than the storage unit 11 that is currently being replenished.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus that forms an image on a recording medium by an inkjet method and a method for calculating a liquid consumption amount by the image forming apparatus.

Background Art

[0002] In an inkjet type image forming apparatus, the ink consumption amount is measured by multiplying image data by the amount of one drop of liquid. The abstract of Patent Document 1 describes the following matters. The dot counter measures the cumulative number of dots of ink ejected from the recording head. The control unit changes the ejection amount of ink ejected from the recording head based on the difference between the calculated value of the ink consumption amount calculated from the cumulative number of dots measured by the dot counter and the measured value of the ink consumption amount determined from the amount of ink in the sub-tank detected by the ink amount sensor. Thus, the apparatus described in Patent Document 1 is not assumed to measure the ink consumption amount during ink replenishment, and it was necessary to stop the printing operation or the like when replenishing ink.

[0003] On the other hand, Patent Document 2 describes an apparatus that enables ink replenishment during operations such as printing by mounting a plurality of cartridges of the same color.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the device described in Patent Document 2 detects the remaining ink level in a cartridge and switches cartridges accordingly, and was not intended to calculate ink consumption. Furthermore, measuring the ink flow rate and pressure from the cartridge was prone to large variations for each displacement, leading to accumulated errors and potentially making it impossible to accurately measure ink consumption. Additionally, it was impossible to measure ink consumption when printing and replenishment, i.e., ink discharge and supply, were performed simultaneously. On the other hand, prioritizing printing and measuring ink consumption could lead to delays in ink replenishment, potentially compromising print quality.

[0006] The present invention has been made in view of the above points, and aims to provide an image forming apparatus and a liquid consumption calculation method that can suitably calculate the amount of liquid consumed even when the liquid is replenished. [Means for solving the problem]

[0007] The present invention, which solves the aforementioned problems, has the following configuration. 1. An image forming apparatus comprising: a recording head that forms an image on a recording medium by discharging a liquid; a plurality of storage units in which the liquid is stored; a supply unit that supplies the stored liquid to the recording head; a plurality of liquid quantity detection units that detect the amount of liquid stored in each of the plurality of storage units; and a control unit that controls the supply unit, wherein the control unit calculates the amount of liquid consumed based on the amount of liquid detected by the liquid quantity detection unit in each of the plurality of storage units, excluding the storage unit in which the liquid is being replenished. 2. The image forming apparatus according to claim 1, wherein a plurality of storage units are connected in series with respect to the recording head, and the control unit calculates the amount of liquid consumed based on the amount of liquid detected by the liquid amount detection unit in the other storage units while replenishing the liquid in the upstream storage unit. 3. The image forming apparatus according to claim 1, wherein the plurality of storage units are connected in parallel to the recording head. 4. The image forming apparatus according to any one of 1 to 3, wherein the control unit calculates the amount of liquid consumed while the recording head is in standby mode, while the recording head is forming an image, while the recording head is undergoing maintenance, and while the liquid is being replenished. 5. The image forming apparatus according to paragraph 1, wherein the control unit calculates the amount of liquid consumed during maintenance of the recording head, and determines that there is an abnormality if the calculated amount of liquid consumed is less than or equal to a predetermined amount. 6. The image forming apparatus according to paragraph 1, wherein the control unit calculates the amount of liquid consumed during maintenance of the recording head, and if the calculated amount of liquid consumed is less than or equal to a predetermined amount, the maintenance of the recording head is re-executed. 7. The image forming apparatus according to 5 or 6, wherein the predetermined amount is set for each type of maintenance. 8. The image forming apparatus according to any one of 1 to 3, wherein the control unit calculates the amount of liquid consumed for each image forming job of the recording head. 9. The image forming apparatus according to paragraph 2, further comprising a replenishment detection unit for detecting the replenishment of the liquid to the uppermost storage unit, wherein the control unit stops the supply of the liquid from the uppermost storage unit to the other storage units by the supply unit while the replenishment operation is detected by the replenishment detection unit. 10. The image forming apparatus according to 9, wherein the replenishment detection unit is an open / close detection unit that detects the opening and closing of the cover of the upstream storage unit located therein, and the control unit stops the supply of the liquid from the upstream storage unit to the other storage units by the supply unit while the open state of the cover is detected by the detection unit. 11. The image forming apparatus according to any one of 1 to 3, wherein the liquid volume detection unit is a weight detection unit that detects the weight of the liquid stored in the storage unit. 12. The image forming apparatus according to any one of 1 to 3, wherein the liquid volume detection unit is a liquid level detection unit that detects the liquid level of the liquid stored in the storage unit. 13. The image forming apparatus according to any one of 1 to 3, wherein the liquid includes an ink, a pre-treatment liquid, and a post-treatment liquid for forming the image, and each of the ink, the pre-treatment liquid, and the apparatus is equipped with a storage unit, a supply unit, and a liquid volume detection unit. 14. The image forming apparatus according to any one of 1 to 3, wherein the liquid includes a cleaning fluid for cleaning the recording head, and the apparatus comprises a cleaning unit for cleaning the recording head with the cleaning fluid supplied from the supply unit. 15. The image forming apparatus according to paragraph 3, wherein some of the plurality of storage units are for replenishing the liquid, and the other parts of the plurality of storage units are for supplying the liquid to the recording head. 16. The image forming apparatus according to 15, wherein the control unit switches between the plurality of storage units for replenishment and for supply. 17. The image forming apparatus according to 11, wherein the control unit calculates the volume of the liquid consumed as the amount of the liquid consumed, based on the specific gravity of the liquid which has been stored in advance. 18. A liquid consumption calculation method performed by the image forming apparatus described in paragraph 1, comprising: an acquisition step in which the control unit repeatedly acquires the amount of liquid detected by a plurality of liquid amount detection units; and a calculation step in which the control unit calculates the liquid consumption based on the repeatedly acquired amount of liquid, wherein in the calculation step, the control unit calculates the liquid consumption based on the amount of liquid detected by the liquid amount detection unit in a storage unit other than the storage unit in which the liquid is being replenished among a plurality of storage units. [Effects of the Invention]

[0008] According to the present invention, the amount of liquid consumed can be suitably calculated even when the liquid is replenished. [Brief explanation of the drawing]

[0009] [Figure 1] This figure schematically shows an image forming apparatus according to the first embodiment of the present invention. [Figure 2]It is a diagram schematically showing an image forming unit of an image forming apparatus according to a first embodiment of the present invention. [Figure 3] It is a diagram schematically showing an image forming unit of an image forming apparatus according to a first embodiment of the present invention, and is a side view seen from the conveyance direction of a recording medium. [Figure 4] It is a diagram schematically showing an image forming unit of an image forming apparatus according to a first embodiment of the present invention, and is a side view seen from the moving direction of a recording head. [Figure 5] It is a diagram schematically showing an image forming unit of an image forming apparatus according to a first embodiment of the present invention, and is a diagram for explaining a cleaning method by a cleaning unit. ed]] [Figure 6] It is a diagram schematically showing an image forming unit of an image forming apparatus according to a first embodiment of the present invention, and is a diagram for explaining a maintenance method by liquid extrusion. [Figure 7] It is a diagram schematically showing an image forming unit of an image forming apparatus according to a first embodiment of the present invention, and is a diagram for explaining a maintenance method by liquid suction. [Figure 8] It is a flowchart for explaining an operation example of an image forming apparatus according to a first embodiment of the present invention, and is a diagram for explaining an operation example of a supply pump. [Figure 9] It is a flowchart for explaining an operation example of an image forming apparatus according to a first embodiment of the present invention, and is a diagram for explaining an operation example of a replenishment pump. [Figure 10] It is a flowchart for explaining an operation example of an image forming apparatus according to a first embodiment of the present invention, and is a diagram for explaining an example of calculating liquid consumption. [Figure 11] It is a diagram schematically showing an image forming unit of an image forming apparatus according to a second embodiment of the present invention, and is a diagram for explaining a cleaning method by a cleaning unit. [Figure 12] It is a diagram schematically showing an image forming unit of an image forming apparatus according to a second embodiment of the present invention, and is a diagram for explaining a maintenance method by liquid suction. [Figure 13]It is a diagram schematically showing an image forming unit of an image forming apparatus according to a second embodiment of the present invention, and is a diagram for explaining a maintenance method by liquid suction. [Figure 14] It is a flowchart for explaining an operation example of an image forming apparatus according to a second embodiment of the present invention, and is a diagram for explaining an example of switching for replenishment and supply of a storage unit. [Figure 15] It is a flowchart for explaining an operation example of an image forming apparatus according to a second embodiment of the present invention, and is a diagram for explaining an example of calculating liquid consumption.

Embodiments for Carrying Out the Invention

[0010] <First Embodiment> Next, embodiments of the present invention will be described in detail with appropriate reference to the drawings. As shown in FIG. 1, an image forming apparatus 1 according to a first embodiment of the present invention is an apparatus that forms, that is, prints an image on a recording medium 9 using a liquid 2 such as ink. Examples of such an image forming apparatus 1 include a copying machine, a printer apparatus, a printing machine, a multifunction machine, and the like. Examples of the recording medium 9 include papers such as paper and envelopes, cloths, resins, and the like. The image forming apparatus 1 includes an image forming apparatus main body 3, an image reading apparatus 4, and an automatic document feeder 5.

[0011] The image forming apparatus main body 3 includes, for example, a storage unit 31, a supply conveyance unit 32, an image forming unit 33A, and a discharge conveyance unit 34. The storage unit 31 is a tray that stores a plurality of stacked recording media 9. The supply conveyance unit 32 takes out the recording mediums 9 stored in the storage unit 31 and conveys them from the storage unit 31 to the image forming unit 33A.

[0012] The image forming unit 33A is a part that forms an image on the recording medium 9 conveyed by the supply conveyance unit 32 based on an image signal transmitted from the image reading apparatus 4. In the present invention, an inkjet method or the like is adopted as the image forming method in this image forming unit 33A. The discharge conveyance unit 34 discharges and conveys the recording medium 9 on which an image has been formed in the image forming unit 33A to the outside of the image forming apparatus main body 3.

[0013] The image reading device 4 optically reads an image from a document transported from the automatic document feeder 5, processes the read image signal, and transmits it to the image forming unit 33A. The automatic document feeder 5 is equipped with a document tray and transports documents placed on the document tray to the image reading device 4.

[0014] The image forming apparatus 1 also includes an operation unit 6, a notification unit 7, and a control unit 8. The operation unit 6 consists of buttons, a touch panel, etc., and outputs control signals to the control unit 8 according to the user's operation. The notification unit 7 consists of a monitor, a speaker, etc., and displays images or outputs sounds based on control signals from the control unit 8. The control unit 8 consists of a CPU (Central Processing Unit), ROM (Read-Only Memory), RAM (Random Access Memory), input / output circuits, etc. Based on the user's operation results in the operation unit 6, the control unit 8 controls the supply transport unit 32, the image forming unit 33A, the discharge transport unit 34, the image reading device 4, the automatic document feeder 5, and the notification unit 7.

[0015] As shown in Figure 2, the image forming unit 33A of the image forming apparatus 1 according to the first embodiment of the present invention comprises a plurality of storage units 11, 12, a supply unit 20, and a plurality of recording heads 30 for each type of liquid 2. Examples of such liquid 2 include pre-treatment liquid, ink, and post-treatment liquid. The pre-treatment liquid is a liquid used to pre-treat the recording medium 9 before an image is formed by the ink. The ink is a liquid used to form an image on the recording medium 9 and is provided for each of several colors. The post-treatment liquid is a liquid used to post-treat the recording medium 9 after an image has been formed by the ink. Furthermore, as shown in Figures 3 and 4, the image forming unit 33A comprises a recording medium transport unit 70 and a plurality of recording head moving units 80.

[0016] <Recording medium transport unit> The recording medium transport unit 70 transports the recording medium 9 within the image forming unit 33A. The recording medium transport unit 70 includes, for example, a pair of transport rollers 71 and 72, a belt 73 wound around the transport rollers 71 and 72, and a drive unit (not shown). The control unit 8 controls the drive unit, which is composed of a motor or the like, to rotate one of the transport rollers 71 and 72, thereby moving the belt 73 and transporting the recording medium 9 placed on the belt 73.

[0017] <Recording head movement unit> A recording head moving unit 80 is provided for each of the multiple recording heads 30 and moves the corresponding recording head 30. The recording head moving unit 80 comprises a frame 81, a guide rail 82, and a drive unit (not shown) provided for each recording head 30. The frame 81 has, for example, a rectangular planar shape. The guide rail 82 is attached to the frame 81 and extends in a direction parallel to the recording medium 9 transported by the recording medium transport unit 70 and perpendicular to the transport direction of the recording medium 9. The control unit 8 controls the drive unit, which is composed of a motor or the like, to move the recording head 30 back and forth along the guide rail 82 in a direction parallel to the recording medium 9 and perpendicular to the transport direction of the recording medium 9.

[0018] Furthermore, as shown in Figure 5, the image forming unit 33A of the image forming apparatus 1 includes a plurality of storage units 11, 12, a supply unit 20, and a cleaning unit 40, corresponding to the cleaning liquid 2. Note that in Figure 5 and the following Figures 6 and 7, for simplification, only the configuration corresponding to any of the pre-treatment liquid, ink, post-treatment liquid, and cleaning liquid is depicted, and in that configuration, only one recording head 30 is depicted.

[0019] <Storage section (main tank)> As shown in Figures 2 and 5, the storage section 11 is located upstream of the storage section 12, i.e., at the uppermost point in the flow of liquid 2, and is the main tank where liquid 2 is stored. The storage section 11 is connected to the storage section 12 by a liquid passage 51 so as to be able to circulate liquid. The storage section 11 is replaceable via a cover 35 formed on the housing of the image forming apparatus body 3.

[0020] <Storage section (sub-tank)> The storage section 12 is located downstream of the storage section 11 and upstream of the recording head 30 or the cleaning section 40, and is a sub-tank in which liquid 2 is stored. One storage section 12 is connected in series to one recording head 30 or one cleaning section 40 by a liquid passage 52 or a liquid passage 53, allowing liquid to flow through it.

[0021] <Supply section> The supply unit 20 is a liquid supply unit that operates based on control signals from the control unit 8 and supplies the liquid 2 stored in the storage units 11 and 12 to the recording head 30 or the cleaning unit 40. As shown in Figure 2, the supply unit 20 that supplies liquid 2 to the recording head 30 includes pump 21 and pump 22. As shown in Figure 5, the supply unit 20 that supplies liquid to the cleaning unit 40 includes pump 21 and pump 23.

[0022] <pump> As shown in Figures 2 and 5, the pump 21 is installed in a liquid passage 51 that connects the storage section 11 and the storage section 12 in a way that allows liquid to flow between them. The pump 21 is a liquid pump that operates based on a control signal from the control unit 8 and supplies the liquid 2 stored in the storage section 11 to the storage section 12.

[0023] <pump> As shown in Figure 2, the pump 22 is an air pump that operates based on a control signal from the control unit 8 and supplies air into the storage unit 12, thereby supplying the liquid 2 stored in the storage unit 12 to the recording head 30 via the liquid passage 52.

[0024] <pump> As shown in Figure 5, the pump 23 is interposed in a liquid passage 53 that connects the storage unit 12 and the cleaning unit 40 in a liquid-flowable manner. The pump 23 is a liquid pump that operates based on a control signal from the control unit 8 and supplies the liquid 2 stored in the storage unit 12 to the cleaning unit 40 via the liquid passage 53.

[0025] <Recording head> As shown in Figures 2 and 5, the recording head 30 forms an image on the main surface of the recording medium 9 by ejecting pre-treatment liquid, ink, or post-treatment liquid as liquid 2 supplied from the storage unit 12 onto the recording medium 9. A single recording head 30 is configured to eject pre-treatment liquid, multiple types of ink, and post-treatment liquid supplied from multiple storage units 12 onto the recording medium 9 (see Figure 3).

[0026] <Cleaning Department> As shown in Figure 5, the cleaning unit 40 cleans the recording head 30 using cleaning fluid, which is liquid 2, supplied from the storage unit 12. The cleaning unit 40 comprises a cleaning bucket 41 in which the cleaning fluid, which is liquid 2, is stored, and a cleaning roller 42 provided inside the cleaning bucket 41. The cleaning unit 40 operates based on a control signal from the control unit 8 and moves the discharge side, i.e., the bottom side, of the recording head 30 in a direction perpendicular to the plane of the paper in Figure 5. As a result, the cleaning roller 42 rotates while contacting the discharge side of the recording head 30, cleaning the discharge surface of the recording head 30 with the cleaning fluid.

[0027] <Sensors> As shown in Figures 2 and 5, the image forming unit 33A includes, for each type of liquid 2, liquid volume detection units 61 and 62, a full tank detection unit 63, a pressure sensor 64, and an open / close detection unit 65.

[0028] <Liquid volume detection unit (for main tank)> As shown in Figures 2 and 5, the liquid volume detection unit 61 repeatedly detects the amount of liquid 2 stored in the storage unit 11 at regular intervals and repeatedly outputs the detection result to the control unit 8 at regular intervals. The liquid volume detection unit 61 may be a weight sensor that detects the weight of the liquid 2 stored in the storage unit 11, or a liquid level sensor that detects the liquid level height of the liquid 2 stored in the storage unit 11.

[0029] <Liquid volume detection unit (for sub-tank)> The liquid volume detection unit 62 repeatedly detects the amount of liquid 2 stored in the storage unit 12 at regular intervals and repeatedly outputs the detection result to the control unit 8 at regular intervals. The liquid volume detection unit 62 may be a weight sensor that detects the weight of the liquid 2 stored in the storage unit 12, or a liquid level sensor that detects the liquid level height of the liquid 2 stored in the storage unit 12.

[0030] <Full Tank Detection Unit (for Sub-tank)> The full-tank detection unit 63 detects that the liquid 2 stored in the storage unit 12 is full and outputs the detection result to the control unit 8. The full-tank detection unit 63 can utilize a liquid level sensor or the like that detects when the liquid level of the liquid 2 stored in the storage unit 12 is at the full-tank position.

[0031] <Pressure Sensor> The pressure sensor 64 detects the pressure of the air supplied to the storage unit 12 by the pump 22 and outputs the detection result to the control unit 8.

[0032] <Open / Close Detection Unit> The open / close detection unit 65 is an example of a replenishment detection unit that detects the replenishment of liquid 2 into the storage unit 11. It detects the open / closed state of the cover 35 as information corresponding to whether or not a replenishment operation is being performed, and outputs the detection result to the control unit 8. Note that the replenishment detection unit is not limited to the open / close detection unit 65 described above, but may also be an installation detection unit that detects whether or not the storage unit 11 is installed in a predetermined position.

[0033] <Image formation process> The control unit 8 supplies the liquid 2 stored in the storage unit 12 to the recording head 30 by operating the pump 22. The control unit 8 can change the amount of air supplied by the pump 22 based on the detection result of the pressure sensor 64. The control unit 8 also supplies the liquid 2 stored in the storage unit 11 to the storage unit 12 by operating the pump 21, and attempts to maintain the amount of liquid 2 stored in the storage unit 12 at full capacity based on the detection result of the full-tank detection unit 63.

[0034] <Actions taken during cleaning> The control unit 8 operates the pump 23 to supply the liquid 2 stored in the storage unit 12 to the recording head 30 or the cleaning unit 40. The control unit 8 also operates the pump 21 to supply the liquid 2 stored in the storage unit 11 to the storage unit 12, and attempts to maintain the amount of liquid 2 stored in the storage unit 12 at full capacity based on the detection result of the full-tank detection unit 63.

[0035] <Maintenance by liquid extrusion> As shown in Figure 6, the image forming apparatus 1 is equipped with a liquid receiving section 71 for maintenance by liquid extrusion. The liquid receiving section 71 moves to the discharge side of the recording head 30 by a control signal from the control unit 8 and receives the liquid 2 discharged from the recording head 30. The liquid 2 received by the liquid receiving section 70 is treated as waste liquid.

[0036] The control unit 8 performs maintenance by liquid extrusion based on the user's operation of the control unit 6. In this case, the control unit 8 pushes the liquid 2 out of the recording head 30 by operating the pump 22. The control unit 8 can also change the amount of air supplied to the pump 22 based on the detection result of the pressure sensor 64.

[0037] <Maintenance using liquid suction> As shown in Figure 7, the image forming apparatus 1 includes a cap section 72 and a suction section 73 as a configuration for maintenance by liquid suction. The cap section 72 moves to the discharge side of the recording head 30 by a control signal from the control unit 8 and receives the liquid 2 sucked from the recording head 30. The liquid 2 received by the cap section 72 is treated as waste liquid. The suction section 73 is a suction pump that operates by a control signal from the control unit 8 and sucks the liquid 2 stored in the recording head 30.

[0038] The control unit 8 performs maintenance by liquid suction based on the user's operation of the control unit 6. In this case, the control unit 8 suctions the liquid 2 from the recording head 30 by activating the suction unit 73.

[0039] The control unit 8 calculates the amount of liquid 2 consumed while the recording head 30 is in standby mode, while the recording head 30 is forming an image (i.e., printing), while the recording head 30 is being maintained, and while the liquid 2 is being replenished in the storage unit 11. The control unit 8 also performs image formation by the recording head 30 and maintenance of the recording head 30 while the liquid 2 is being replenished in the storage unit 11.

[0040] The control unit 8 repeatedly acquires the detection results from the liquid volume detection units 61 and 62 at regular intervals. Based on the current detection result and the previous detection result, the control unit 8 calculates the current consumption of liquid 2. [Current consumption of liquid 2] = [Sum of detection results from liquid volume detection units 61 and 62 from the previous session] - [Sum of detection results from liquid volume detection units 61 and 62 from the current session] Furthermore, the control unit 8 calculates the cumulative consumption of liquid 2 up to the present based on the amount of liquid 2 consumed each time. [Cumulative consumption of Liquid 2 up to this point] = [Cumulative consumption of Liquid 2 up to the previous point] + [Current consumption of Liquid 2]

[0041] If the liquid volume detection units 61 and 62 are weight sensors that detect the weight of the liquid 2, the control unit 8 substitutes the detection results of the liquid volume detection units 61 and 62 directly into the above formula. Here, the liquid volume detection units 61 and 62, as weight sensors, may each detect the sum of the weight of the liquid 2 and the weight of the storage unit 11.12.

[0042] If the liquid volume detection units 61 and 62 are liquid level sensors that detect the liquid level of liquid 2, the control unit 8 converts the detection results of the liquid volume detection units 61 and 62 into the volume or weight of liquid 2 and substitutes the conversion result into the formula described above. The control unit 8 can calculate the volume of liquid 2 based on the bottom area of ​​the storage units 11 and 12 stored in advance, or the relationship between the liquid level of liquid 2 in each storage unit 11 and 12 and the volume of liquid 2. The control unit 8 can also calculate the weight of liquid 2 based on the volume of liquid 2 and the specific gravity of liquid 2 stored in advance.

[0043] While replenishing the storage unit 11 with liquid 2, the control unit 8 calculates the amount of liquid 2 consumed based on the detection result of the liquid volume detection unit 62, without using the detection result of the liquid volume detection unit 61. [Current consumption of liquid 2] = [Previous detection result of liquid volume detection unit 62] - [Current detection result of liquid volume detection unit 62] The control unit 8 determines that if the detection result of the open / close detection unit 65 indicates that the cover 35 is closed, then the liquid 2 is not being replenished into the storage unit 11. The control unit 8 determines that if the detection result of the open / close detection unit 65 indicates that the cover 35 is open, then the liquid 2 is being replenished into the storage unit 11. This allows the control unit 8 to prevent miscalculations caused by the increase in liquid 2 due to replenishment.

[0044] The control unit 8 permits the operation of the pump 21 if the detection result of the open / close detection unit 65 indicates that the cover 35 is closed. The control unit 8 prohibits the operation of the pump 21 if the detection result of the open / close detection unit 65 indicates that the cover 35 is open. In this way, the control unit 8 can prevent malfunction of the pump 21 and create an environment suitable for replenishing the liquid 2.

[0045] The control unit 8 calculates the amount of liquid 2 consumed from the start to the end of each image formation, i.e., job, of the recording head 30. Here, a job is defined by the user's operation of the operation unit 6, and includes the content of the image formation, i.e., the print, the size of the recording medium 9, the number of copies, etc.

[0046] The control unit 8 calculates the amount of liquid 2 consumed from the start to the end of each maintenance of the recording head 30. The control unit 8 also determines that the system is normal if the amount of liquid 2 consumed during maintenance, i.e., from the start to the end of maintenance, is greater than a first predetermined amount, and outputs the determination result to the notification unit 7. The control unit 8 also determines that the system is abnormal if the amount of liquid 2 consumed during maintenance, i.e., from the start to the end of maintenance, is less than or equal to the first predetermined amount, and outputs the determination result to the notification unit 7. Possible causes of such abnormalities include clogging of the recording head 30 preventing the liquid 2 from being discharged properly, or malfunctions in the pumps 21, 22, and 23 preventing the liquid 2 from being supplied properly.

[0047] Furthermore, the control unit 8 may be configured to re-execute maintenance if the amount of liquid 2 consumed during maintenance, i.e., from the start to the end of maintenance, is less than or equal to a first predetermined amount.

[0048] The control unit 8 calculates the amount of liquid 2 consumed from the start to the end of standby while the recording head 30 is in standby mode. The control unit 8 determines that the system is functioning normally if the amount of liquid 2 consumed during standby (i.e., from the start to the end of standby) is less than or equal to a second predetermined amount. The control unit 8 determines that the system is functioning abnormally if the amount of liquid 2 consumed during standby (i.e., from the start to the end of standby) is greater than the second predetermined amount, and outputs the determination result to the notification unit 7. Possible causes of such abnormalities include leakage of liquid 2.

[0049] <Example of operation: Example of operation of the pump that supplies water from the storage unit (which acts as a sub-tank) to the recording head> Next, an example of the operation of the pump 22 in the image forming apparatus 1 according to the first embodiment of the present invention will be described with reference to the flowchart in Figure 8. The operation example of the pump 23 for cleaning fluid is substantially the same.

[0050] As shown in Figure 8, if the image forming unit 33A is forming an image (Yes in step S1), the control unit 8 monitors the pressure sensor 64, i.e., acquires the detection result of the pressure sensor 64 (step S2). Subsequently, the control unit 8 operates the pump 22 so that the detection result of the pressure sensor 64 falls to a predetermined value or within a predetermined range, thereby supplying the liquid 2 stored in the storage unit 12 to the recording head 30 (step S3). After step S3 is completed, this flow returns to step S1. If the image forming unit 33A is not forming an image (No in step S1), this flow ends.

[0051] Furthermore, the control unit 8 operates the pump 22 so that the detection result of the pressure sensor 64 is within a predetermined value or a predetermined range, even during maintenance by liquid extrusion. It is preferable that the predetermined value, or the upper and lower limits of the predetermined range, during maintenance by liquid extrusion, are set to be smaller than the predetermined value, or the upper and lower limits of the predetermined range, during image formation. Similarly, the control unit 8 operates the suction unit 73 so that the detection result of the pressure sensor 64 is within a predetermined value or a predetermined range, even during maintenance by liquid suction. It is preferable that the predetermined value, or the upper and lower limits of the predetermined range, during maintenance by liquid suction, are set to be equal to the predetermined value, or the upper and lower limits of the predetermined range, during image formation.

[0052] <Example of operation: Example of operation of the pump used to replenish the storage tank as a sub-tank> Next, an example of the operation of the pump 21 in the image forming apparatus 1 according to the first embodiment of the present invention will be described with reference to the flowchart in Figure 9.

[0053] As shown in Figure 9, if the detection result of the open / close detection unit 65 indicates that the cover 35 is closed (Yes in step S11), this flow proceeds to step S12. If the detection result of the full tank detection unit 63 does not indicate that the tank is full (No in step S12), the control unit 8 operates the pump 21 to supply liquid 2 from the storage unit 11 to the storage unit 12 (step S13). If the detection result of the full tank detection unit 63 indicates that the tank is full (Yes in step S12), the control unit 8 stops the supply of liquid 2 from the storage unit 11 to the storage unit 12 by stopping the pump 21 (step S14). After the execution of step S13 or step S14, this flow returns to step S11.

[0054] <Example of operation: Calculation of liquid consumption> Next, an example of calculating liquid consumption in the image forming apparatus 1 according to the first embodiment of the present invention will be explained with reference to the flowchart in Figure 10.

[0055] As shown in Figure 10, the control unit 8 acquires the detection results of the liquid volume detection units 61 and 62 corresponding to the storage units 11 and 12 (step S21). Next, the control unit 8 calculates the current liquid consumption based on the previous detection results of the liquid volume detection units 61 and 62 and the current detection results of the liquid volume detection units 61 and 62 (step S22). The control unit 8 also calculates the current cumulative liquid consumption based on the current liquid consumption and the cumulative liquid consumption up to the previous time (step S22). If the cover 35 is open, the control unit 8 calculates the current liquid consumption and cumulative liquid consumption based on the detection results of the liquid volume detection unit 62, without using the detection results of the liquid volume detection unit 61.

[0056] Next, the control unit 8 waits for a predetermined time (step S23). In other words, step S21 is repeated after a predetermined time interval. After step S23 is executed, the control unit 8 determines whether a job is running (step S24) or whether maintenance is being performed (step S26). The order of steps S24 and S26 can be changed.

[0057] If an image formation job is currently running (Yes in step S24), the control unit 8 calculates the cumulative liquid consumption from the start of the job (step S25). In step S25, the control unit 8 can calculate the cumulative liquid consumption from the start to the end of the job based on the calculation result in step S22. Alternatively, if it is determined in step S24 that the job has finished, that is, immediately after the job has finished, this flow may proceed to step S25. In this case, in step S25, the control unit 8 can omit the calculation of cumulative liquid consumption during job execution and calculate the liquid consumption of the job based on the cumulative liquid consumption at the start and end of the job. [Job liquid consumption] = [Cumulative liquid consumption at job completion] - [Cumulative liquid consumption at job start]

[0058] Furthermore, if maintenance is in progress (Yes in step S26), the control unit 8 calculates the cumulative liquid consumption since the start of maintenance (step S27). In repeated steps of step S27, the control unit 8 can calculate the cumulative liquid consumption from the start to the end of maintenance based on the calculation result in step S22. Alternatively, if it is determined in step S26 that maintenance has finished, that is, immediately after the end of maintenance, this flow may proceed to step S27. In this case, in step S27, the control unit 8 can omit the calculation of cumulative liquid consumption during maintenance and calculate the liquid consumption for maintenance based on the cumulative liquid consumption at the start and end of maintenance. [Liquid consumption during maintenance] = [Cumulative liquid consumption at the end of maintenance] - [Cumulative liquid consumption at the start of maintenance]

[0059] If the answer in steps S24 and S26 is No, this flow returns to step S21. Similarly, after the execution of step S25 or step S27, this flow also returns to step S21.

[0060] The image forming apparatus 1 according to the first embodiment of the present invention comprises a recording head 30 that forms an image on a recording medium by discharging a liquid 2, and a plurality of storage units 11, 12 in which the liquid 2 is stored. The image forming apparatus 1 also comprises a supply unit 20 that supplies the stored liquid 2 to the recording head 30, and a plurality of liquid volume detection units 61, 62 that detect the amount of liquid stored in the plurality of storage units 11, 12, respectively. The image forming apparatus 1 also comprises a control unit 8 that controls the supply unit 20. The control unit 8 calculates the consumption of the liquid 2 based on the amount of liquid 2 detected by the liquid volume detection units 61, 62 in the storage units 11, 12 other than the storage unit in which the liquid 2 is being replenished. Therefore, the image forming apparatus 1 can suitably calculate the amount of liquid 2 consumed, even when liquid 2 is replenished.

[0061] The multiple storage units 11 and 12 are connected in series with respect to the recording head 30. The control unit 8 calculates the amount of liquid 2 consumed based on the amount of liquid 2 detected by the liquid amount detection unit 62 in the other storage units 12 while replenishing the liquid 2 in the uppermost storage unit 11. Therefore, the image forming apparatus 1 can suitably calculate the amount of liquid 2 consumed while replenishing the liquid 2 in the so-called main tank.

[0062] The control unit 8 calculates the amount of liquid 2 consumed while the recording head 30 is in standby mode, while the recording head 30 is forming an image, while the recording head 30 is undergoing maintenance, and while the liquid 2 is being replenished. Therefore, the image forming apparatus 1 can continuously calculate the consumption of liquid 2 without interruption, and can detect a malfunction, for example, by observing that liquid 2 is being consumed while the recording head 30 is in standby mode.

[0063] The control unit 8 calculates the amount of liquid 2 consumed during maintenance of the recording head 30, and determines that there is an abnormality if the calculated amount of liquid 2 consumed is less than or equal to a predetermined amount. Therefore, the image forming apparatus 1 can suitably determine maintenance abnormalities, such as clogging of the recording head 30. Furthermore, even if maintenance is performed while the liquid 2 is being replenished, the image forming apparatus 1 can suitably calculate the amount of liquid 2 consumed during maintenance.

[0064] The control unit 8 calculates the amount of liquid 2 consumed during maintenance of the recording head 30, and if the calculated amount of liquid 2 consumed is less than or equal to a predetermined amount, it re-executes the maintenance of the recording head 30. Therefore, the image forming apparatus 1 can return the recording head 30 and other components to a suitable state by performing maintenance again.

[0065] The predetermined amount is set for each type of maintenance. Therefore, the image forming apparatus 1 can perform appropriate abnormality detection or maintenance re-execution according to the type of maintenance.

[0066] The control unit 8 calculates the amount of liquid 2 consumed for each image forming job of the recording head 30. Therefore, the image forming apparatus 1 can suitably calculate the amount of liquid 2 consumed per job. Furthermore, the image forming apparatus 1 can suitably calculate the amount of liquid 2 consumed per job even when a job is executed while liquid 2 is being replenished.

[0067] The image forming apparatus 1 includes a replenishment detection unit that detects when the liquid 2 is being replenished in the uppermost storage unit 11. The control unit 8 stops the supply of the liquid from the uppermost storage unit 11 to the other storage units 12 by the supply unit 20 while the replenishment operation is detected by the replenishment detection unit. Therefore, the image forming apparatus 1 can effectively prevent malfunctions of the supply unit 20.

[0068] The replenishment detection unit is an open / close detection unit 65 that detects the opening and closing of the cover 35 at the location where the uppermost storage unit 11 is located. The control unit 8 stops the supply of the liquid 2 from the uppermost storage unit 11 to the other storage units 12 by the supply unit 20 while the open / close detection unit 65 detects that the cover 35 is open. Therefore, the image forming apparatus 1 can suitably detect the replenishment of liquid 2 using a simple method of detecting the opening and closing of the cover 35.

[0069] The liquid volume detection units 61 and 62 are weight detection units that detect the weight of the liquid 2 stored in the storage units 11 and 12. Therefore, the image forming apparatus 1 can suitably calculate the amount of liquid 2 consumed based on its weight.

[0070] The liquid volume detection units 61 and 62 are liquid level detection units that detect the liquid level of the liquid 2 stored in the storage units 11 and 12. Therefore, the image forming apparatus 1 can suitably calculate the amount of liquid 2 consumed based on the liquid level. Furthermore, when the image forming apparatus 1 uses a full-tank detection unit for controlling the storage section, the liquid level detection unit can also function as the full-tank detection unit.

[0071] The liquid 2 includes the ink, pre-treatment liquid, and post-treatment liquid used to form the image. The image forming apparatus 1 includes the storage units 11, 12, the supply unit 20, and the liquid volume detection units 61, 62 for each of the ink, pre-treatment liquid, and post-treatment liquid. Therefore, the image forming apparatus 1 can suitably calculate the consumption of liquid 2 with respect to the pre-treatment solution, ink, and post-treatment solution required for image formation.

[0072] The liquid 2 includes a cleaning fluid for cleaning the recording head 30. The image forming apparatus 1 includes a cleaning unit 40 that cleans the recording head 30 with the cleaning fluid supplied from the storage units 11 and 12. Therefore, the image forming apparatus 1 can suitably calculate the amount of liquid 2 consumed with respect to the cleaning fluid required for cleaning the recording head 30.

[0073] The control unit 8 calculates the volume of liquid 2 consumed as the amount of liquid 2 consumed, based on the specific gravity of liquid 2 that has been stored in advance. Therefore, the image forming apparatus 1 can calculate the amount of liquid 2 consumed as a volume that is easy for the user to understand and inform the user of this amount.

[0074] Furthermore, the liquid consumption calculation method according to the first embodiment of the present invention is a liquid consumption calculation method performed by the image forming apparatus 1. The liquid consumption calculation method includes an acquisition step in which the control unit 8 repeatedly acquires the amount of liquid 2 detected by a plurality of liquid volume detection units 61, 62, and a calculation step in which the control unit 8 calculates the amount of liquid 2 consumed based on the repeatedly acquired amounts of liquid 2. In the calculation step, the control unit 8 calculates the amount of liquid 2 consumed based on the amount of liquid 2 detected by the liquid volume detection units 61, 62 in the storage units 11, 12 other than the storage unit 11, 12 that is currently being refilled with liquid 2. Therefore, according to the liquid consumption calculation method, the consumption of liquid 2 can be suitably calculated even when liquid 2 is replenished.

[0075] <Second Embodiment> Next, the image forming apparatus according to the second embodiment of the present invention will be described, focusing on the differences from the image forming apparatus 1 according to the first embodiment. As shown in Figures 11, 12, and 13, the image forming section 33B of the image forming apparatus 1 according to the second embodiment of the present invention is equipped with a plurality of storage sections 12. Furthermore, the image forming section 33B of the image forming apparatus 1 is not equipped with a liquid volume detection section 61. Figure 11 corresponds to Figure 5 in the first embodiment and depicts the configuration on the cleaning section 40 side. Figure 12 corresponds to Figure 6 in the first embodiment and depicts the configuration necessary for maintenance by liquid extrusion. Figure 13 corresponds to Figure 7 in the first embodiment and depicts the configuration necessary for maintenance by liquid suction.

[0076] Multiple storage units 12 are arranged in parallel with respect to one storage unit 11 and one recording head 30. The image forming unit 33B of the image forming apparatus 1 includes a liquid volume detection unit 62, a full tank detection unit 63, an upstream on-off valve 81, and a downstream on-off valve 82, corresponding to the multiple storage units 12.

[0077] Pump 21 is located upstream of the branching section of the liquid channel 51. The upstream on-off valve 81 is located downstream of the branching section of the liquid channel 51. Pump 22 has multiple storage sections 12 It is connected to supply air. Pump 23 is located downstream of the branching point of the liquid passage 53. The downstream on-off valve 82 is located upstream of the branching point of the liquid passage 52 or liquid passage 53.

[0078] The control unit 8 sets at least one of the multiple storage units 12 for replenishing liquid 2 from the storage unit 11, and sets the remaining storage units 12 for supplying liquid 2 to the recording head 30 or the cleaning unit 40. The downstream on-off valve 82 corresponding to the storage unit 12 set for replenishment is always closed, and the upstream on-off valve 81 corresponding to the storage unit 12 set for supply is always closed.

[0079] The control unit 8 controls the upstream on-off valve 81 to be open and operates the pump 21 with respect to the replenishment storage unit 12, thereby supplying liquid 2 from the storage unit 11 to the storage unit 12. When the full tank detection unit 63 detects that the storage unit is full, the control unit 8 controls the upstream on-off valve 81 to be closed and stops the pump 21. Through this control, the control unit 8 maintains the replenishment storage unit 12 in a full state.

[0080] The control unit 8 controls the downstream on-off valve 82 to be in the open state with respect to the supply storage unit 12 and operates the pump 22 or pump 23 to supply liquid 2 from the storage unit 12 to the recording head 30 or cleaning unit 40.

[0081] Based on the detection result of the liquid volume detection unit 62, the control unit 8 resets the supply storage unit 12 to the replenishment storage unit 12 when the amount of liquid 2 stored in the supply storage unit 12 falls below a third predetermined amount, for example, when it becomes empty, and also resets at least one of the replenishment storage units 12 to the supply storage unit 12. If the amount of liquid 2 stored in the supply storage unit 12 is greater than the third predetermined amount, the control unit 8 maintains the supply and replenishment settings of the storage unit 12.

[0082] The control unit 8 acquires the detection results from the liquid volume detection unit 62 at regular intervals. Based on the current detection result and the previous detection result, the control unit 8 calculates the current consumption amount of liquid 2. [Current consumption of liquid 2] = [Total value of detection results from liquid volume detection unit 62 last time] - [Total value of detection results from liquid volume detection unit 62 this time]

[0083] When replenishing liquid 2 into the storage unit 12 for replenishment, the control unit 8 calculates the amount of liquid 2 consumed based on the detection result of the liquid volume detection unit 62 corresponding to the storage unit 12 that is not being replenished, rather than using the detection result of the liquid volume detection unit 62 corresponding to the storage unit 12 that is being replenished. [Current consumption of liquid 2] = [Total value of detection results from liquid level detection unit 62 excluding the current replenishment] - [Total value of detection results from liquid level detection unit 62 excluding the current replenishment]

[0084] In this embodiment, the control unit 8 determines that the liquid 2 replenishment operation is in progress when the upstream on-off valve 81 corresponding to the replenishment storage unit 12 is open and the pump 21 is operating. In this state, the liquid 2 stored in the storage unit 11 is supplied to the replenishment storage unit 12.

[0085] <Maintenance by liquid extrusion> The control unit 8 performs maintenance by pushing out liquid based on the user's operation of the control unit 6. In this case, the control unit 8 opens the downstream on-off valve 82 corresponding to the storage unit 12 set for supply and operates the pump 22 to push out the liquid 2 from the recording head 30 (see Figure 12). During this maintenance, the control unit 8 closes the downstream on-off valve 82 corresponding to the storage unit 12 set for replenishment.

[0086] <Maintenance using liquid suction> The control unit 8 performs maintenance by liquid suction based on the user's operation of the control unit 6. In this case, the control unit 8 opens the downstream on-off valve 82 corresponding to the storage unit 12 set for supply and operates the suction unit 73 to suction liquid 2 from the recording head 30 (see Figure 13). During this maintenance, the control unit 8 closes the downstream on-off valve 82 corresponding to the storage unit 12 set for replenishment.

[0087] <Example of operation: Example of operation of the pump that supplies water from the storage unit (which acts as a sub-tank) to the recording head> Next, an example of the operation of the pump 22 in the image forming apparatus 1 according to the second embodiment of the present invention will be described with reference to the flowchart in Figure 14. The operation example of the pump 23 for cleaning fluid is substantially the same. Furthermore, the control of the upstream on-off valve 81 and the downstream on-off valve 82 will be omitted in the following description.

[0088] As shown in Figure 14, if the image forming unit 33B is forming an image (Yes in step S31), the control unit 8 monitors the pressure sensor 64, that is, it obtains the detection result of the pressure sensor 64 (step S32). Next, the control unit 8 determines whether the detection result of the liquid volume detection unit 62 of the storage unit 12 set for supply indicates empty (step S33). If it indicates empty (Yes in step S33), the control unit 8 switches the storage unit 12 currently set for supply to replenishment, and switches the storage unit 12 currently set for replenishment to supply (step S34).

[0089] If the result in step S33 is No, and after step S34 is executed, the control unit 8 operates the pump 22 so that the detection result of the pressure sensor 64 becomes a predetermined value, thereby supplying the liquid 2 stored in the storage unit 12 to the recording head 30 (step S35). After step S35 is executed, this flow returns to step S31. Also, if the image forming unit 33B is not forming an image (No in step S31), this flow ends.

[0090] Furthermore, the control unit 8 replenishes the storage unit 12, which was switched to replenishment mode in step S34, by operating the pump 21 to supply the liquid stored in the storage unit 11.

[0091] <Example of operation: Calculation of liquid consumption> Next, an example of calculating liquid consumption in the image forming apparatus 1 according to the second embodiment of the present invention will be explained with reference to the flowchart in Figure 15. In the following explanation, the control of the upstream on-off valve 81 and the downstream on-off valve 82 will be omitted.

[0092] As shown in Figure 15, the control unit 8 acquires the detection results of the liquid volume detection units 62 corresponding to the multiple storage units 12 (step S41). Next, the control unit 8 calculates the current liquid consumption based on the previous detection result of the liquid volume detection unit 62 and the current detection result of the liquid volume detection unit 62 (step S42). The control unit 8 also calculates the current cumulative liquid consumption based on the current liquid consumption and the cumulative liquid consumption up to the previous time (step S42). Note that if the replenishment storage unit 12 is being replenished with liquid 2, the control unit 8 calculates the current liquid consumption and cumulative liquid consumption based on the detection result of the supply liquid volume detection unit 62, without using the detection result of the replenishment liquid volume detection unit 62.

[0093] Next, the control unit 8 waits for a predetermined time (step S43). In other words, step S41 is repeated after a predetermined time interval. After step S43 is executed, the control unit 8 determines whether a job is running (step S44) or whether maintenance is being performed (step S46). The order of steps S44 and S46 can be changed.

[0094] Here, if an image formation job is in progress (Yes in step S44), the control unit 8 calculates the cumulative liquid consumption from the start of the job (step S45). In repeated steps of step S45, the control unit 8 can calculate the cumulative liquid consumption from the start of the job to the end of the job based on the calculation result in step S42. Alternatively, if it is determined in step S44 that the job has finished, that is, immediately after the job has finished, this flow may proceed to step S45. In this case, in step S45, the control unit 8 can omit the calculation of cumulative liquid consumption during job execution and calculate the liquid consumption of the job based on the cumulative liquid consumption at the start and end of the job. [Job liquid consumption] = [Cumulative liquid consumption at job completion] - [Cumulative liquid consumption at job start]

[0095] Furthermore, if maintenance is in progress (Yes in step S46), the control unit 8 calculates the cumulative liquid consumption since the start of maintenance (step S47). In step S47, the control unit 8 can calculate the cumulative liquid consumption from the start to the end of maintenance based on the calculation result in step S42. Alternatively, if it is determined in step S46 that maintenance has finished, that is, immediately after the maintenance is finished, this flow may proceed to step S47. In this case, in step S47, the control unit 8 can omit the calculation of cumulative liquid consumption during maintenance and calculate the liquid consumption for maintenance based on the cumulative liquid consumption at the start and end of maintenance. [Liquid consumption during maintenance] = [Cumulative liquid consumption at the end of maintenance] - [Cumulative liquid consumption at the start of maintenance]

[0096] If the answer in steps S44 and S46 is No, this flow returns to step S41. Similarly, after the execution of step S45 or step S47, this flow also returns to step S41.

[0097] Multiple storage units 12 are connected in parallel to the recording head 30. Therefore, when the storage units 12 are connected in parallel, the image forming apparatus 1 can suitably calculate the amount of liquid 2 consumed during replenishment of liquid 2.

[0098] Some of the multiple storage units 12 are for replenishing the liquid 2, and the other parts of the multiple storage units 12 are for supplying the liquid 2 to the recording head 30. Therefore, when the image forming apparatus 1 uses the storage unit 12 for replenishment and supply, it can suitably calculate the amount of liquid 2 consumed during replenishment.

[0099] The control unit 8 switches between the multiple storage units 12 for replenishment and for supply. Therefore, when the amount of liquid 2 stored in the supply storage unit 12 becomes low, the image forming apparatus 1 can switch between supply and replenishment, and replenish the liquid 2 without interrupting image forming, maintenance, or cleaning.

[0100] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above and can be modified as appropriate without departing from the spirit of the invention. For example, the image forming unit 33B of the image forming apparatus 1 according to the second embodiment may be configured to include three or more storage units 12, a liquid volume detection unit 62, a full tank detection unit 63, an upstream on-off valve 81, and a downstream on-off valve 82 for one type of liquid 2. In this case, the control unit 8 can set some of the three or more storage units 12 for supply to the recording head 30 or cleaning unit 40, and set the other three or more storage units 12 for replenishment from the storage unit 11. [Explanation of Symbols]

[0101] 1. Image forming apparatus 2. Liquids (pre-treatment solution, ink, post-treatment solution, cleaning solution) 9. Recording media 11. Storage section (main tank) 12 Storage section (sub-tank) 20 Supply section 30 Recording heads 33A,33B Image forming section 40 Cleaning Department 61,62 Liquid volume detection unit 65 Opening / closing detection unit (replenishment work detection unit)

Claims

1. A recording head that forms an image on a recording medium by ejecting liquid, Multiple storage sections in which the aforementioned liquid is stored, A supply unit that supplies the stored liquid to the recording head, Multiple liquid volume detection units for detecting the amount of liquid stored in each of the multiple storage units, A control unit that controls the supply unit, Equipped with, The control unit calculates the amount of liquid consumed based on the amount of liquid detected by the liquid amount detection unit in one of the storage units, excluding the storage unit that is currently being refilled. Image forming apparatus.

2. Multiple storage units are connected in series with respect to the recording head. The control unit calculates the amount of liquid consumed in the other storage units based on the amount of liquid detected by the liquid amount detection unit in the other storage units while replenishing the liquid in the uppermost storage unit. The image forming apparatus according to claim 1.

3. Multiple storage units are connected in parallel to the recording head. The image forming apparatus according to claim 1.

4. The control unit calculates the amount of liquid consumed while the recording head is in standby mode, while the recording head is forming an image, while the recording head is undergoing maintenance, and while the liquid is being replenished. The image forming apparatus according to any one of claims 1 to 3.

5. The control unit, During maintenance of the recording head, the amount of liquid consumed is calculated. If the calculated amount of the liquid consumed is less than or equal to a predetermined amount, it is determined to be abnormal. The image forming apparatus according to claim 1.

6. The control unit, During maintenance of the recording head, the amount of liquid consumed is calculated. If the calculated amount of liquid consumed is less than or equal to a predetermined amount, the maintenance of the recording head will be re-executed. The image forming apparatus according to claim 1.

7. The predetermined amount is set for each type of maintenance. The image forming apparatus according to claim 5 or claim 6.

8. The control unit calculates the amount of liquid consumed for each image formation job of the recording head. The image forming apparatus according to any one of claims 1 to 3.

9. It includes a replenishment detection unit that detects the replenishment of the liquid to the upstream storage unit, The control unit stops the supply of the liquid from the upstream storage unit to the other storage units by the supply unit while the replenishment detection unit detects that a replenishment operation is in progress. The image forming apparatus according to claim 2.

10. The replenishment detection unit is an open / close detection unit that detects the open / closed state of the cover of the upstream storage unit located at the uppermost part of the storage unit. The control unit stops the supply of the liquid from the upstream storage unit to the other storage units by the supply unit while the open / close detection unit detects that the cover is open. The image forming apparatus according to claim 9.

11. The liquid volume detection unit is a weight detection unit that detects the weight of the liquid stored in the storage unit. The image forming apparatus according to any one of claims 1 to 3.

12. The liquid volume detection unit is a liquid level detection unit that detects the liquid level height of the liquid stored in the storage unit. The image forming apparatus according to any one of claims 1 to 3.

13. The liquid includes an ink, a pre-treatment solution, and a post-treatment solution that form the image. With respect to the ink, the pretreatment liquid, and the posttreatment liquid, the following are provided: a storage unit, a supply unit, and a liquid volume detection unit. The image forming apparatus according to any one of claims 1 to 3.

14. The liquid includes a cleaning solution for cleaning the recording head. The system includes a cleaning unit that cleans the recording head with the cleaning fluid supplied from the storage unit. The image forming apparatus according to any one of claims 1 to 3.

15. Some of the multiple storage units are for replenishing the liquid, The other parts of the multiple storage units are for supplying the liquid to the recording head. The image forming apparatus according to claim 3.

16. The control unit switches between the multiple storage units for replenishment and for supply. The image forming apparatus according to claim 15.

17. The control unit calculates the volume of the liquid consumed as the amount of the liquid consumed, based on the specific gravity of the liquid which has been stored in advance. The image forming apparatus according to claim 11.

18. A method for calculating liquid consumption performed by an image forming apparatus according to claim 1, The control unit performs an acquisition step of repeatedly acquiring the amount of liquid detected by a plurality of liquid volume detection units, The control unit performs a calculation step of calculating the amount of liquid consumed based on the amount of liquid repeatedly obtained, Includes, In the calculation step, the control unit calculates the amount of liquid consumed based on the amount of liquid detected by the liquid amount detection unit in one of the storage units other than the storage unit that is currently being refilled. Methods for calculating liquid consumption.

Images