Image forming device and image forming method

Abstract

To provide an image forming device and an image forming method capable of resolving an abnormal state of a nozzle without reducing productivity.SOLUTION: An image forming device 100 comprises: a piezoelectric element 30C that discharges ink droplets from a nozzle in response to application of a first drive voltage; an execution processing unit 81 that executes image forming processing to form images on respective sheets conveyed sequentially; a detection processing unit 82 that detects an abnormal state in which ink droplets are not discharged in response to the application of the first drive voltage during execution of the image forming processing; and an application processing unit 83 that applies to the piezoelectric element 30C a second drive voltage higher than the first drive voltage during a non-facing period in which the nozzle does not face the sheet while the image forming processing is being executed when the detection processing unit 82 detects the abnormal state.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] An inkjet image forming apparatus includes a discharge unit such as a piezoelectric element that discharges ink droplets from a nozzle in response to application of a predetermined first drive voltage. In this type of image forming apparatus, an abnormal state may occur in which ink droplets are not discharged in response to application of the first drive voltage. In response to this, a related art image forming apparatus is known that, when the abnormal state is detected, suspends image formation processing, caps the nozzle, and applies a second drive voltage higher than the first drive voltage to the discharge unit (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-286124 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the image forming apparatus according to the above-mentioned related art, the image forming process is interrupted, which reduces productivity.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus and an image forming method that can eliminate abnormal nozzle conditions without reducing productivity. [Means for solving the problem]

[0006] According to one aspect of the present invention, an image forming apparatus includes a discharge unit, an execution processing unit, a detection processing unit, and an application processing unit. The discharge unit causes ink droplets to be discharged from nozzles in response to application of a predetermined first drive voltage. The execution processing unit uses the discharge unit to execute an image formation process that forms an image on each of sheets that are conveyed sequentially. The detection processing unit detects an abnormal state during execution of the image formation process in which the ink droplets are not discharged in response to application of the first drive voltage. When the detection processing unit detects the abnormal state, the application processing unit applies a second drive voltage higher than the first drive voltage to the discharge unit during a non-opposing period in which the nozzles are not facing the sheet during execution of the image formation process.

[0007] An image forming method according to another aspect of the present invention is performed by an image forming apparatus including an ejection unit that ejects ink droplets from nozzles in response to application of a predetermined first drive voltage, and includes an execution step, a detection step, and an application step. In the execution step, an image formation process is performed using the ejection unit to form an image on each of sequentially conveyed sheets. In the detection step, an abnormal state in which the ink droplets are not ejected in response to application of the first drive voltage is detected during the image formation process. In the application step, if the abnormal state is detected in the detection step, a second drive voltage higher than the first drive voltage is applied to the ejection unit during a non-opposing period in which the nozzles are not facing the sheet during the image formation process. [Effects of the Invention]

[0008] According to the present invention, it is possible to eliminate the abnormal state of the nozzle without reducing productivity. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the configuration of the image forming section and the transport unit of the image forming apparatus according to the embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing the configuration of the periphery of the nozzles of the image forming apparatus according to the embodiment of the present invention. [Figure 4] FIG. 4 is a block diagram showing the system configuration of the image forming apparatus according to the embodiment of the present invention. [Figure 5] FIG. 5 is a flowchart showing an example of a nozzle inspection process executed in the image forming apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

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

[0011] [Configuration of image forming apparatus 100] First, the configuration of an image forming apparatus 100 according to an embodiment of the present invention will be described with reference to Figures 1 to 4. Here, Figure 1 is a cross-sectional view showing the configuration of the image forming apparatus 100. Also, Figure 2 is a plan view showing the configuration of the image forming section 3 and the transport unit 4. Also, Figure 3 is a cross-sectional view showing the configuration of the nozzle 30A, the pressure chamber 30B, the piezoelectric element 30C, and the individual flow path 30D. In Figure 1, the sheet transport path R11 is indicated by a two-dot chain line.

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

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

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

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

[0016] The image forming unit 3 forms an image on a sheet based on image data of an image formation target. As shown in FIG.

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

[0018] As shown in FIG. 2, each of the line heads 31 to 34 has a plurality of recording heads 30. Each of the recording heads 30 ejects ink toward a sheet transported by the transport unit 4. Each of the recording heads 30 provided in the line head 31 ejects black ink. Each of the recording heads 30 provided in the line head 32 ejects cyan ink. Each of the recording heads 30 provided in the line head 33 ejects magenta ink. Each of the recording heads 30 provided in the line head 34 ejects yellow ink.

[0019] Each of the recording heads 30 includes a plurality of nozzles 30A (see FIGS. 2 and 3) that eject ink. Each of the nozzles 30A is provided on the surface of the recording head 30 that faces the sheet transported by the transport unit 4.

[0020] Each recording head 30 also includes a pressure chamber 30B (see FIG. 3), a piezoelectric element 30C (see FIG. 3), and an individual flow path 30D (see FIG. 3) corresponding to each nozzle 30A. The pressure chamber 30B is connected to the nozzle 30A and contains ink. The piezoelectric element 30C ejects ink droplets from the nozzle 30A in response to application of a predetermined first drive voltage. Specifically, the piezoelectric element 30C changes the pressure in the pressure chamber 30B in response to application of the first drive voltage, thereby ejecting ink droplets from the nozzle 30A. The individual flow path 30D is an ink flow path provided between the pressure chamber 30B and a common flow path (not shown) shared by the multiple nozzles 30A. The common flow path is connected to multiple individual flow paths 30D corresponding to the multiple nozzles 30A. The common flow path is connected to an ink supply unit (not shown) that supplies ink to each pressure chamber 30B. The piezoelectric element 30C is an example of an ejection unit of the present invention.

[0021] Each recording head 30 also includes a drive circuit 30E (see FIG. 4), a power supply unit 30F (see FIG. 4), and a voltage detection unit 30G (see FIG. 4) corresponding to each piezoelectric element 30C. The power supply unit 30F generates the first drive voltage and outputs the generated first drive voltage to the drive circuit 30E. The power supply unit 30F can also generate a second drive voltage higher than the first drive voltage and output the generated second drive voltage to the drive circuit 30E. The drive circuit 30E drives the piezoelectric elements 30C based on data input from the second control unit 8. Specifically, the drive circuit 30E drives the piezoelectric elements 30C by switching between outputting and not outputting the first drive voltage input from the power supply unit 30F to the piezoelectric elements 30C. The voltage detection unit 30G detects the voltage across both ends of the piezoelectric elements 30C. Note that the power supply unit 30F may be provided for each group consisting of multiple piezoelectric elements 30C.

[0022] The line head 31 includes three recording heads 30 arranged in a staggered pattern along the width direction D12. Similarly to the line head 31, each of the other line heads 32 to 34 also includes three recording heads 30 arranged in a staggered pattern along the width direction D12. Note that FIG. 2 shows the image forming unit 3 as viewed from above in FIG. 1.

[0023] The head frame 35 supports the line heads 31 to 34. The head frame 35 is supported by the housing 1. The number of line heads included in the image forming unit 3 does not have to be limited to four. Furthermore, the number of recording heads 30 included in each of the line heads 31 to 34 does not have to be limited to three.

[0024] As shown in FIG. 1, the transport unit 4 is disposed below the line heads 31 to 34. The transport unit 4 transports a sheet while facing the recording head 30. As shown in FIG. 1, the transport unit 4 includes a transport belt 41 on which the sheet is placed, a first tension roller 42, a second tension roller 43, and a third tension roller 44 that tension the transport belt 41, and a transport frame 45 that supports these. The gap between the transport belt 41 and the recording head 30 is adjusted so that the gap between the surface of the sheet and the recording head 30 during image formation is a predetermined distance (for example, 1 mm).

[0025] The first tension roller 42 is driven to rotate by a rotational driving force supplied from a motor (not shown). As a result, the conveyor belt 41 rotates in a direction that allows the sheet to be conveyed in the conveying direction D11 (see FIG. 1). The conveying unit 4 also includes a suction unit (not shown) that sucks air through a number of through-holes formed in the conveyor belt 41 to attract the sheet to the conveyor belt 41. A pressure roller 46 is provided above the first tension roller 42 to press the sheet against the conveyor belt 41 for conveyance.

[0026] The transport unit 4 includes a cleaning unit 47 shown in FIG. 1. The cleaning unit 47 cleans the surface (outer periphery) of the transport belt 41. For example, the cleaning unit 47 includes a cleaning member, a feed roller, a take-up roller, and a contact roller. The cleaning member is a sheet-like member such as a nonwoven fabric used to wipe off ink adhering to the surface of the transport belt 41. The feed roller feeds out the cleaning member. The take-up roller takes up the cleaning member fed by the feed roller. The contact roller is provided on the movement path of the cleaning member from the feed roller to the take-up roller and brings the cleaning member into contact with the surface of the transport belt 41. In the cleaning unit 47, the take-up roller is driven, so that the area of ​​the cleaning member where ink is adhering (the area used to wipe off the ink) moves toward the take-up roller. Note that the cleaning unit 47 is not limited to the configuration described above.

[0027] The operation display unit 5 has a display unit such as a liquid crystal display that displays various information in response to control instructions from the first control unit 7, and an operation unit such as operation keys or a touch panel that inputs various information to the first control unit 7 in response to user operations. The operation display unit 5 is provided on the top surface of the housing 1.

[0028] The storage unit 6 is a non-volatile storage device, such as a flash memory.

[0029] The first control unit 7 performs overall control of the image forming apparatus 100. As shown in FIG. 4, the first control unit 7 includes a CPU 7A, a ROM 7B, and a RAM 7C. The CPU 7A is a processor that executes various types of arithmetic processing. The ROM 7B is a non-volatile storage device that stores in advance information such as control programs for causing the CPU 7A to execute various types of processing. The RAM 7C is a volatile or non-volatile storage device that is used as a temporary storage memory (work area) for the various types of processing executed by the CPU 7A. The CPU 7A performs overall control of the image forming apparatus 100 by executing the various control programs that are stored in advance in the ROM 7B.

[0030] When the image forming process is executed, the first control unit 7 inputs the image data to the second control unit 8. The image forming process is a process in which an image is formed on each of the sheets that are conveyed sequentially using each of the piezoelectric elements 30C included in the image forming unit 3.

[0031] The second control section 8 controls the sheet conveying section 2, the image forming section 3, and the conveying unit 4. For example, the second control section 8 is configured with an electronic circuit such as an integrated circuit (ASIC, DSP).

[0032] The second control unit 8 controls the image forming unit 3 based on the image data input from the first control unit 7.

[0033] Specifically, the second control unit 8 performs a conversion process to convert each pixel data included in the image data into either ejection pixel data used to eject ink from the nozzle 30A corresponding to the pixel data, or non-ejection pixel data used to not eject ink from the nozzle 30A corresponding to the pixel data.

[0034] The second control unit 8 then inputs the ejection pixel data or non-ejection pixel data acquired by the conversion process to the corresponding drive circuit 30E. The drive circuit 30E outputs the first drive voltage in response to the input of the ejection pixel data. Furthermore, when the non-ejection pixel data is input, the drive circuit 30E does not output the first drive voltage.

[0035] Incidentally, an abnormal state may occur in the image forming apparatus 100, in which ink droplets are not ejected in response to the application of the first drive voltage. In response to this, a related art image forming apparatus is known in which, when the abnormal state is detected, the image forming process is interrupted, each nozzle 30A is capped, and the second drive voltage, which is higher than the first drive voltage, is applied to each piezoelectric element 30C.

[0036] However, in the image forming apparatus according to the above-mentioned related art, the image forming process is interrupted, which reduces productivity.

[0037] In contrast to this, the image forming apparatus 100 according to the embodiment of the present invention can eliminate the abnormal state of the nozzle 30A without reducing productivity, as will be described below.

[0038] [Configuration of second control unit 8] Next, the configuration of the second control unit 8 will be described with reference to FIG.

[0039] As shown in FIG. 4, the second control unit 8 includes an execution processing unit 81, a detection processing unit 82, and an application processing unit 83.

[0040] The execution processing unit 81, the detection processing unit 82, and the application processing unit 83 may be provided in the first control unit 7. Specifically, the CPU 7A of the first control unit 7 may function as each of the above-mentioned processing units by executing the control program pre-stored in the ROM 7B. In this case, the image forming apparatus 100 does not need to include the second control unit 8.

[0041] The execution processing unit 81 executes the image forming process.

[0042] Specifically, the execution processing section 81 controls the sheet conveying section 2, the image forming section 3, and the conveying unit 4 to execute the image forming process.

[0043] The detection processing unit 82 detects the abnormal state in which ink droplets are not ejected in response to application of the first drive voltage during the execution of the image forming process.

[0044] Specifically, the detection processing unit 82 detects the abnormal state for each nozzle 30A.

[0045] For example, the detection processing unit 82 detects the abnormal state based on a change in voltage of the piezoelectric element 30C after application of the first drive voltage. Specifically, the detection processing unit 82 determines that ink droplets have been ejected in response to the application of the first drive voltage when the change in voltage of the piezoelectric element 30C detected by the voltage detection unit 30G after application of the first drive voltage exceeds a predetermined specific value. Furthermore, the detection processing unit 82 determines that ink droplets have not been ejected in response to the application of the first drive voltage when the change in voltage of the piezoelectric element 30C detected by the voltage detection unit 30G after application of the first drive voltage does not exceed the specific value, thereby determining that the abnormal state exists.

[0046] The image forming apparatus 100 may include an imaging unit that captures an image of the surface of the conveyor belt 41 before cleaning by the cleaning unit 47. In this case, the detection processing unit 82 may form a predetermined test chart on the surface of the conveyor belt 41 using the image forming unit 3, capture an image of the test chart using the imaging unit, and detect the abnormal state based on the image capture result by the imaging unit.

[0047] When the abnormal state is detected by the detection processing unit 82, the application processing unit 83 applies the second drive voltage, which is higher than the first drive voltage, to the piezoelectric element 30C during a non-opposing period in which the nozzle 30A is not facing the sheet while the image formation process is being performed.

[0048] The non-opposing period is the period from when the trailing edge of the sheet passes the position facing the abnormal nozzle 30A until when the leading edge of the next sheet reaches the position facing the abnormal nozzle 30A. Note that the non-opposing period may also be the period from when the trailing edge of the last sheet on which an image is formed in the image forming process passes the position facing the abnormal nozzle 30A.

[0049] Specifically, during the non-opposing period, the application processing unit 83 causes the power supply unit 30F corresponding to the abnormal nozzle 30A to generate the second drive voltage, and causes the drive circuit 30E corresponding to the abnormal nozzle 30A to output the second drive voltage.

[0050] If the change in voltage of piezoelectric element 30C after application of the second drive voltage detected by voltage detection unit 30G does not exceed the specific value, that is, if the abnormal condition is not resolved by application of the second drive voltage, application processing unit 83 may apply the second drive voltage again to piezoelectric element 30C corresponding to nozzle 30A in the abnormal condition. Furthermore, if the number of times the second drive voltage has been applied to piezoelectric element 30C corresponding to nozzle 30A in the abnormal condition reaches a predetermined number, application processing unit 83 may notify the user to that effect.

[0051] [Nozzle inspection process] 5, the image forming method of the present invention will be described below, along with an example of the procedure of the nozzle inspection process executed by the second control unit 8 in the image forming apparatus 100. Here, steps S11, S12, etc. represent the numbers of the process procedures (steps) executed by the second control unit 8.

[0052] The nozzle inspection process is executed together with the image formation process when the image formation process is executed. The step of executing the image formation process is an example of an execution step of the present invention, and is executed by the execution processing unit 81 of the second control unit 8.

[0053] The nozzle inspection process is executed for each nozzle 30 A. Below, the nozzle inspection process corresponding to one of the plurality of nozzles 30 A (hereinafter referred to as the “target nozzle”) will be described.

[0054] <Step S11> First, in step S11, the second control section 8 determines whether or not the image forming process has ended.

[0055] Here, if the second control unit 8 determines that the image forming process has ended (Yes in S11), it ends the nozzle inspection process. If the image forming process has not ended (No in S11), the second control unit 8 shifts the process to step S12.

[0056] <Step S12> In step S12, the second control unit 8 determines whether or not the timing for applying the first drive voltage to the piezoelectric element 30C corresponding to the target nozzle has arrived.

[0057] Specifically, when the timing for inputting the ejection pixel data to the drive circuit 30E corresponding to the target nozzle arrives, the second control unit 8 determines that the timing for applying the first drive voltage to the piezoelectric element 30C corresponding to the target nozzle has arrived.

[0058] Here, when the second control unit 8 determines that the timing for applying the first drive voltage to the piezoelectric element 30C corresponding to the target nozzle has arrived (Yes in S12), it shifts the process to step S13. On the other hand, when the timing for applying the first drive voltage to the piezoelectric element 30C corresponding to the target nozzle has not arrived (No in S12), the second control unit 8 shifts the process to step S11.

[0059] <Step S13> In step S13, the second control unit 8 determines whether or not the abnormal state has been detected for the target nozzle. The process of step S13 is an example of a detection step of the present invention, and is executed by the detection processing unit 82 of the second control unit 8.

[0060] Specifically, the second control unit 8 determines that the target nozzle is in the abnormal state when the change in voltage of the piezoelectric element 30C after application of the first drive voltage detected by the voltage detection unit 30G does not exceed the specific value.

[0061] Here, if the second control unit 8 determines that the abnormal state has been detected for the target nozzle (Yes in S13), it shifts the process to step S14. On the other hand, if the abnormal state has not been detected for the target nozzle (No in S13), the second control unit 8 shifts the process to step S11. As a result, the target nozzle is inspected every time the timing for applying the first drive voltage to the piezoelectric element 30C corresponding to the target nozzle arrives.

[0062] <Step S14> In step S14, the second control unit 8 determines whether the non-opposing period has started.

[0063] Specifically, the second control unit 8 determines that the non-opposing period has started when the sheet that was facing the target nozzle when the processing of the immediately preceding step S12 was executed passes through the position facing the target nozzle.

[0064] Here, when the second control unit 8 determines that the non-opposing period has started (Yes in S14), it shifts the process to step S15. On the other hand, when the non-opposing period has not started (No in S14), the second control unit 8 waits for the start of the non-opposing period in step S14.

[0065] <Step S15> In step S15, the second control unit 8 executes an application process to apply the second drive voltage to the piezoelectric element 30C corresponding to the target nozzle. The process of step S15 is an example of an application step of the present invention, and is executed by the application processing unit 83 of the second control unit 8.

[0066] Specifically, the second control unit 8 causes the power supply unit 30F corresponding to the target nozzle to generate the second drive voltage, and causes the drive circuit 30E corresponding to the target nozzle to output the second drive voltage.

[0067] The ink droplets ejected onto the surface of the conveyor belt 41 by executing the process of step S15 are removed from the surface of the conveyor belt 41 by the cleaning unit 47.

[0068] In this way, in the image forming apparatus 100, when the abnormal state is detected for any of the nozzles 30A, the second drive voltage is applied to the piezoelectric element 30C corresponding to that nozzle 30A during the non-opposing period in which the nozzle 30A is not facing the sheet during the image formation process. This makes it possible to resolve the abnormal state without interrupting the image formation process. Therefore, compared to conventional configurations that require interruptions in the image formation process, it is possible to resolve the abnormal state of the nozzle 30A without reducing productivity.

[0069] [Notes on the Invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0070] <Appendix 1> an execution processing unit that executes an image formation process that uses the ejection unit to eject ink droplets from a nozzle in response to application of a predetermined first drive voltage; a detection processing unit that detects an abnormal state in which the ejection of ink droplets in response to application of the first drive voltage does not occur during execution of the image formation process; and an application processing unit that, when the abnormal state is detected by the detection processing unit, applies a second drive voltage higher than the first drive voltage to the ejection unit during a non-opposing period in which the nozzle is not facing the sheet during execution of the image formation process.

[0071] <Appendix 2> 2. The image forming apparatus according to claim 1, wherein the detection processing unit detects the abnormal state based on a voltage change of the ejection unit after the first drive voltage is applied.

[0072] <Appendix 3> 3. The image forming apparatus according to claim 1, further comprising: a conveyor belt that conveys the sheet below the ejection unit; and a cleaning unit that cleans the surface of the conveyor belt.

[0073] <Appendix 4> An image forming method performed by an image forming device having an ejection unit that ejects ink droplets from a nozzle in response to application of a predetermined first drive voltage, the image forming method including: an execution step of executing an image formation process using the ejection unit to form an image on each of sheets that are transported sequentially; a detection step of detecting an abnormal state in which ink droplets are not ejected in response to application of the first drive voltage during execution of the image formation process; and an application step of applying a second drive voltage higher than the first drive voltage to the ejection unit during a non-opposing period in which the nozzle is not facing the sheet during execution of the image formation process when the abnormal state is detected by the detection step. [Explanation of symbols]

[0074] 1 chassis 2 Sheet transport section 3 Image forming unit 4 Transport unit 5 Operation display section 6 Memory section 7 First Control Section 8 Second control section 30 Recording head 30A nozzle 30B Pressure chamber 30C piezoelectric element 30E drive circuit 30F power supply section 30G voltage detection unit 41 Conveyor belt 47 Cleaning Department 81 Execution processing unit 82 Detection processing section 83 Application processing section 100 Image forming device

Claims

1. an ejection unit that ejects ink droplets from a nozzle in response to application of a predetermined first drive voltage; an execution processing unit that executes an image forming process to form an image on each of the sheets that are conveyed sequentially using the ejection unit; a detection processing unit that detects an abnormal state in which the ink droplets are not ejected in response to application of the first driving voltage during execution of the image forming process; an application processing unit that, when the abnormal state is detected by the detection processing unit, applies a second drive voltage higher than the first drive voltage to the ejection unit during a non-opposing period in which the nozzles are not opposed to the sheet during execution of the image forming process; An image forming apparatus comprising:

2. the detection processing unit detects the abnormal state based on a voltage change of the ejection unit after the first drive voltage is applied. The image forming apparatus according to claim 1 .

3. a conveyor belt that conveys the sheet below the discharge portion; a cleaning unit that cleans the surface of the conveyor belt; The image forming apparatus according to claim 1 or 2, comprising:

4. 1. An image forming method executed by an image forming apparatus including an ejection unit that ejects ink droplets from nozzles in response to application of a predetermined first drive voltage, an execution step of executing an image forming process of forming an image on each of the sheets conveyed sequentially using the ejection unit; a detection step of detecting an abnormal state in which the ink droplets are not ejected in response to application of the first driving voltage during execution of the image forming process; an application step of applying a second drive voltage higher than the first drive voltage to the ejection section during a non-opposing period in which the nozzles are not opposed to the sheet during execution of the image forming process when the abnormal state is detected by the detection step; An image forming method comprising:

Images