Ink ejection inspection device, ink ejection inspection method, ink ejection inspection program, ink ejection device, and image formation device

Abstract

To provide an ink ejection inspection device that can accurately sense an ink ejection state for each nozzle.SOLUTION: An ink ejection inspection device, which inspects states of ink ejection from a plurality of nozzles provided in an ink ejection device, comprises: a head driving control part that applies inspecting voltages for ink ejection inspection to the nozzles, after a stand-by period of time during which effect of application of the driving voltages for image formation to the nozzles is further eliminated, after an image formation period during which the driving voltages are applied to the nozzles ends; and a state determining part that determines states of ink ejection of the nozzles, on the basis of residual vibrations of the nozzles obtained through the application of the inspecting voltages.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an ink discharge inspection device, an ink discharge inspection method, an ink discharge inspection program, an ink discharge device, and an image forming apparatus. [Background technology]

[0002] An inkjet type image forming apparatus has an ink ejection device. The ink ejection device ejects ink droplets from the nozzles by driving a piezoelectric element provided in each nozzle with a driving element. Such an ink ejection device is capable of detecting the ink ejection state of each nozzle based on residual vibrations that occur when an inspection signal is applied to each nozzle, and various detection methods have been proposed. For example, in the following Patent Document 1, after printing on one sheet of recording paper is completed, a detection signal (inspection signal) is output to each nozzle before the next recording paper is positioned at a predetermined position by the conveyance of a conveyor belt, and a judgment is made as to whether the ejection state of each nozzle is good or bad. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-231882 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, immediately after printing is completed, residual vibrations occur in the nozzles due to the application of the drive signal for printing. Therefore, if a test signal is applied to the nozzles immediately after printing is completed, the residual vibrations generated by this test signal will be added to the residual vibrations caused by the application of the drive signal. This makes it difficult to accurately detect the ink ejection state.

[0005] Furthermore, immediately after printing, there is variation in the temperature of the nozzle itself and the temperature of the ink near the nozzle due to the printing ejection frequency, and if testing is performed immediately after printing, the waveform of the residual vibration will vary, making accurate measurement difficult.

[0006] Therefore, an object of the present invention is to provide an ink ejection inspection device, an ink ejection inspection method, and an ink ejection inspection program capable of accurately detecting the ink ejection status of each nozzle, and further to provide an ink ejection device and an image forming device capable of forming images through ink ejection controlled with high precision. [Means for solving the problem]

[0007] In order to achieve this objective, the present invention is an ink ejection inspection device for inspecting the ink ejection state from a plurality of nozzles provided in an ink ejection device, and includes a head drive control unit that applies an inspection voltage for ink ejection inspection to each nozzle after an image formation period in which a drive voltage for image formation is applied to each nozzle has ended, and after a waiting period until the effect of applying the drive voltage to each nozzle has converged, and a status determination unit that determines the ink ejection state of each nozzle based on the residual vibration of each nozzle obtained by applying the inspection voltage. Effect of the Invention

[0008] According to the present invention, it is possible to provide an ink ejection inspection device, an ink ejection inspection method, and an ink ejection inspection program capable of accurately detecting the ink ejection status of each nozzle, and further to provide an ink ejection device and an image forming device capable of forming images through ink ejection controlled with high precision. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of an image forming apparatus according to the first embodiment. [Diagram 2]FIG. 2 is a bottom view of each head unit included in the ink ejection device included in the image forming apparatus according to the first embodiment. [Diagram 3] FIG. 3 is a diagram for explaining the configuration of an ink ejection device included in the image forming apparatus according to the first embodiment. [Figure 4] FIG. 4 is a block diagram of a main part of the image forming apparatus according to the first embodiment. [Diagram 5] FIG. 5 is a flowchart showing the ink discharge inspection method according to the first embodiment. [Figure 6] FIG. 6 is a diagram (part 1) for explaining the standby period in the ink discharge inspection method according to the first embodiment. [Figure 7] FIG. 7 is a diagram (part 2) illustrating the standby period in the ink discharge inspection method according to the first embodiment. [Figure 8] FIG. 8 is a diagram for explaining image formation including the ink discharge inspection method according to the embodiment. [Figure 9] FIG. 9 is a block diagram of a main part of an image forming apparatus according to the second embodiment. [Figure 10] FIG. 10 is a diagram (part 1) for explaining the standby period in the ink discharge inspection method according to the second embodiment. [Figure 11] FIG. 11 is a diagram (part 2) for explaining the standby period in the ink discharge inspection method according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of an ink discharge inspection device, an ink discharge inspection method, an ink discharge inspection program, an ink discharge device, and an image forming device to which the present invention is applied will be described in detail with reference to the drawings. Note that common components in each embodiment are given the same reference numerals, and duplicated descriptions will be omitted.

[0011] -First embodiment- Image forming device FIG. 1 is a diagram showing the configuration of an image forming apparatus 1 according to the first embodiment. The image forming apparatus 1 shown in this figure is an inkjet type, and includes a medium supply unit 10, an image forming unit 20 having an ink ejection device 24, a medium discharge unit 30, and a control device 40, and forms an image on a recording medium P. The recording medium P is in the form of a sheet, and in addition to paper such as plain paper or coated paper, various media such as fabric or sheet-like resin on which ink can be fixed when it lands on the main surface of the sheet can be used. The configuration of each part of such an image forming apparatus 1 will be described below.

[0012] <Media supply section 10> The medium supply unit 10 has a paper feed tray 11 that stores the recording medium P, and a supply unit 12 that transports the recording medium P from the paper feed tray 11 to the image forming unit 20. The recording medium P transported from the paper feed tray 11 to the image forming unit 20 is further transported from the image forming unit 20 to the medium discharge unit 30. For this reason, the following description will be given assuming that the arrangement direction of the medium supply unit 10, the image forming unit 20, and the medium discharge unit 30 is the transport direction [x] of the recording medium P.

[0013] <Image forming unit 20> The image forming section 20 includes a medium transport device 21, a delivery unit 22, a heating section 23, an ink ejection device 24, a curing light irradiation device 25, an image reading device 26, and a delivery section 27. These components are configured as follows.

[0014] [Medium conveying device 21] The medium transport device 21 is a cylindrical transport drum, the side peripheral surface of which serves as a transport surface 21a that adsorbs and holds the recording medium P. With the recording medium P held on the transport surface 21a, the medium transport device 21 rotates in one rotation direction [x1] (counterclockwise in the drawing) around the central axis of the cylinder as the rotation axis. Thus, the medium transport device 21 functions as a medium transport section that transports the recording medium P adsorbed and held on the transport surface 21a in the rotation direction [x1] along a path along the transport surface 21a.

[0015] [Delivery Unit 22] The delivery unit 22 picks up the recording medium P transported from the supply unit 12 of the medium supply section 10 by holding one end of the recording medium P, and delivers the recording medium P to the transport surface 21 a of the medium transport device 21 .

[0016] [Heating section 23] The heating section 23 is provided downstream of the delivery unit 22 in the conveying direction [x] of the recording medium P and the rotation direction [x1] of the medium conveying device 21, and heats the recording medium P so that the recording medium P conveyed by the medium conveying device 21 has a temperature within a predetermined range.

[0017] [Ink ejection device 24] The ink ejection device 24 includes a plurality of head units 240 provided downstream of the heating unit 23 in the transport direction [x] of the recording medium P and the rotation direction [x1] of the medium transport device 21. As an example, the image forming apparatus 1 in this embodiment is of a single-pass type in which the plurality of head units 240 are arranged in order from the upstream side in the transport direction [x] of the recording medium P.

[0018] FIG. 2 is a bottom view of each head unit 240 included in the ink ejection device included in the image forming apparatus according to the first embodiment, and is a view of one of the head units 240 shown in FIG. 1 as viewed from the transport surface 21a side of the medium transport device 21. The head unit 240 shown in FIG. 1 and FIG. 2 has a plurality of ink heads 241 arranged along an ink ejection surface 240a facing the transport surface 21a (see FIG. 1) of the medium transport device 21. In the illustrated example, two ink heads 241 are considered as one set, and a plurality of sets (here, eight sets) of ink heads 241 are arranged in two rows in a staggered pattern. In each ink head 241, the ink ejection openings of each nozzle 242 are arranged on the surface arranged on the ink ejection surface 240a of the head unit 240.

[0019] Each nozzle 242 has an ink chamber for storing ink and an ejection opening for ejecting ink. The ink chamber has a head chip disposed on the bottom surface. The head chip is of the piezo type, which uses a piezoelectric element as a driving source for ejecting ink droplets.

[0020] 3 is a diagram for explaining the configuration of the ink ejection device 24 included in the image forming apparatus according to the first embodiment, and is a diagram showing the transport surface 21a of the medium transport device 21 as viewed through the ink ejection surface 240a of each head unit 240. Note that, for ease of explanation, FIG. 3 shows an ink head 241 in each head unit 240, in which nozzles 242 are arranged in a row.

[0021] 3, the ink ejection device 24 has a configuration in which a head unit 240y for yellow (Y), a head unit 240m for magenta (M), a head unit 240c for cyan (C), and a head unit 240k for black (K) are arranged in this order from the downstream side of the transport direction [x] of the recording medium P. Each head unit 240 is arranged across a transport width direction [y] perpendicular to the transport direction [x] of the recording medium P, and ejects ink across the transport width direction [y] of the recording medium P. Each head unit 240 ejects ink onto the recording medium P held on the transport surface 21a of the medium transport device 21 at an appropriate timing according to the rotation of the medium transport device 21.

[0022] 4 is a block diagram of the main parts of the image forming apparatus 1 according to the first embodiment. As shown in this figure, the ink ejection device 24 has an image data processing unit 24a and a head drive processing unit 24b as functional elements for controlling the driving of the nozzles 242 of each ink head 241. The image data processing unit 24a and the head drive processing unit 24b are configured by a computer and function as an ink ejection inspection device that determines the ink ejection state from each nozzle 242 of each ink head 241. The computer is hardware used as a so-called computer. The computer includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and other memories.

[0023] Of these, the image data processing unit 24a buffers image data sent from a control unit 43, which will be described later, and converts the image data into head ejection data.

[0024] The head drive processing unit 24b processes the drive of the head and reverberation vibration. The head drive processing unit 24b includes a head drive control unit 24b-1, a head drive waveform generating unit 24b-2, a signal input unit 24b-3, and a state determining unit 24b-4.

[0025] The head drive control unit 24b-1 transmits nozzle ejection data and drive control signals to the nozzle drive unit 241a of each ink head 241 based on the image data transmitted from the image data processing unit 24a, the data from the status determination unit 24b-4, and the image formation timing signal transmitted from the medium conveying device 21.

[0026] The head drive waveform generating section 24b-2 generates a drive waveform for each nozzle 242 provided in each ink head 241 based on a signal from the head drive control section 24b-1.

[0027] Further, the signal input unit 24b-3 acquires a signal (vibration waveform) obtained by converting the vibration of each nozzle 242 into a voltage from the nozzle drive unit 241a of each ink head 241. In this vibration waveform, the waveform of the residual vibration generated in the nozzle 242 appears immediately after a pulse wave is applied to the nozzle 242. Such a waveform of the residual vibration becomes a different waveform depending on the ink ejection state from the nozzle. Therefore, based on the waveform of the residual vibration acquired by the signal input unit 24b-3, it is possible to determine whether the ink ejection state is normal or not.

[0028] The state determination unit 24b-4 determines the state of each nozzle based on the vibration waveform input to the signal input unit 24b-3. The state of the nozzle determined by the state determination unit 24b-4 is whether the ink ejection state is normal or not. Further, the state determination unit 24b-4 determines whether the state of the nozzle is a state in which the ink ejection inspection can be performed or a period for waiting for the execution of the ink ejection inspection. Further, the state determination unit 24b-4 transmits the determination result to the head drive control unit 24b-1.

[0029] The control and determination procedures implemented in the image data processing unit 24a and the head drive processing unit 24b as described above are a program stored in the ROM in advance or a stored program loaded from an external device to the RAM or non-volatile storage. This control program causes a computer to execute the steps described in the subsequent control method of the image forming apparatus.

[0030] [Hardening light irradiation device 25] Returning to FIG. 1, the hardening light irradiation device 25 is provided on the downstream side of the ink ejection device 24 in the conveyance direction [x] of the recording medium P and the rotation direction [x1] of the medium conveyance device 21. The hardening light irradiation device 25 irradiates the recording medium P held on the conveyance surface 21a of the medium conveyance device 21 with energy rays such as ultraviolet rays to harden and fix the ink ejected onto the recording medium P.

[0031] [Image reading device 26] The image reading device 26 is provided downstream of the curing light irradiation device 25 in the conveying direction [x] of the recording medium P, and reads an image formed on the surface of the recording medium P.

[0032] [Delivery Department 27] The delivery unit 27 is located between the medium transport device 21 and the medium discharge unit 30, and is provided downstream of the image reading device 26 and upstream of the delivery unit 22 in the transport direction [x] of the recording medium P. The delivery unit 27 holds and picks up one end of the recording medium P being transported on the transport surface 21a of the medium transport device 21, and sends the recording medium P onto the discharge tray 31 of the medium discharge unit 30.

[0033] <Media discharge section 30> The medium discharge section 30 has a plate-shaped discharge tray 31 on which the recording medium P discharged from the image forming section 20 is placed, and stores the recording medium P after image formation.

[0034] <Control device 40> The control device 40 controls the driving of each member constituting the medium supply unit 10, the image forming unit 20, and the medium discharge unit 30. Such a control device 40 includes an operation unit 41, a display unit 42, and a control unit 43, and is connected to each of the medium supply unit 10, the image forming unit 20, and the medium discharge unit 30.

[0035] [Operation unit 41] Of these, the operation unit 41 is a section for inputting various settings related to image formation performed using this image forming apparatus 1. Furthermore, such operation unit 41 may be an external device such as a personal computer or a printer controller capable of communicating with a control unit 43 described below for the purpose of transferring data therebetween.

[0036] [Display section 42] The display unit 42 displays the contents of the operations performed in the operation unit 41, the contents set in accordance with the operations performed in the operation unit 41, and other information in accordance with the instructions of the control unit 43. The display unit 42 is a notification unit that issues notifications in accordance with the instructions of the control unit 43.

[0037] [Control unit 43] Based on the operation of the operation unit 41, the control unit 43 processes image data input from an external device and controls the operation of each driving part of the image forming apparatus 1. Such a control unit 43 is configured by a computer.

[0038] The control unit 43 forms an image on the recording medium P by controlling the driving of each unit constituting the medium supply unit 10, the image forming unit 20, and the medium discharge unit 30. The control procedure implemented by the control unit 43 is a program stored in advance in a ROM as a control program for controlling the operation of each unit of the image forming apparatus 1, or a program stored and loaded from an external device into a RAM or non-volatile storage. This control program causes a computer to execute the steps described below in the control method for the image forming apparatus.

[0039] The control procedure by the control unit 43 having the above-mentioned functional units will be described in detail in the next ink inspection ejection method.

[0040] <Ink discharge inspection method> Next, an ink discharge inspection method according to an embodiment will be described. Fig. 5 is a flowchart showing the ink discharge inspection method according to the first embodiment, and shows the procedure carried out by the image data processing unit 24a and head drive processing unit 24b (see Fig. 4) constituting the ink discharge inspection device described above by executing an ink discharge inspection program. The ink discharge inspection method according to the embodiment will be described below in the order shown in the flowchart of Fig. 5, with reference to Figs. 1 to 4 and other figures.

[0041] <Step S101> In step S101, the head drive control unit 24b-1 starts forming an image on the recording medium P by ejecting ink from each nozzle 242 in accordance with an instruction from the control unit 43. At this time, the head drive control unit 24b-1 detects that the nozzle row of each head unit 204 has reached the image formation area Pa of the recording medium P based on a timing signal for image formation sent from the medium conveying device 21, and thereby starts ejecting ink from the nozzles 242 arranged in each nozzle row. Here, the nozzle row refers to one row of nozzles 242 arranged in the conveying width direction [y] as shown in FIG. 3.

[0042] <Step S102> In the next step S102, the head drive control unit 24b-1 determines whether the nozzle row that started image formation in step S101 has left the image formation area Pa. This determination is a determination of whether each nozzle 242 of the nozzle row is in the image formation period [D0] (see FIG. 3), i.e., whether the image formation period has ended. The head drive control unit 24b-1 makes this determination based on a timing signal from the medium conveying device 21 and information from the image data processing unit 24a. If the head drive control unit 24b-1 determines that the nozzle row has left the image formation area Pa (YES), it proceeds to the next step S103.

[0043] <Step S103> In step S103, the head drive controller 24b-1 stops the ejection of ink from each nozzle 242 in the nozzle row that started image formation in step S101.

[0044] <Step S104> In step S104, the state determination unit 24b-4 determines whether or not the waiting period [D1] has ended for each nozzle 242 of the nozzle row that stopped ejecting ink in step S103, based on the vibration waveform input to the signal input unit 24b-3. Here, the waiting period [D1] is a period during which application of a test voltage to each nozzle 242 for ink ejection inspection is waited for after image formation is completed. This waiting period [D1] is a period until the effect of application of a drive voltage to the nozzle 242 for image formation on each nozzle 242 is eliminated. Here, this waiting period [D1] is a period until residual vibration occurring in the nozzle due to application of a drive voltage to the nozzle 242 for image formation is stabilized.

[0045] 6 is a diagram (part 1) for explaining the waiting period [D1] of the ink ejection inspection method according to the first embodiment, showing the drive signal waveform [W1] applied to the nozzle and the vibration waveform [W2] output by converting the vibration generated in the nozzle into a voltage. As shown in FIG. 6, when a pulse wave [p1] for image formation is applied to the nozzle as the drive signal waveform [W1], a residual vibration [W2r] due to the nozzle vibration appears in the vibration waveform [W2] immediately thereafter.

[0046] After stopping the ink ejection in step S103, the state determination unit 24b-4 determines that the waiting period [D1] has ended (YES) at the convergence time [t1] when the amount of change in the vibration waveform [W2] input to the signal input unit 24b-3 falls within a predetermined range. The amount of change in this case is, for example, the magnitude of the amplitude of the vibration waveform [W2], and is set within a range that does not affect the ink ejection test to be performed next.

[0047] Here, this waiting period [D1] includes a switching period [D2] required for signal processing to switch the drive signal for image formation to the test signal for ink discharge testing. Therefore, if the end point [t2] of the switching period [D2] is earlier than the convergence point [t1], the waiting period [D1] should be until the convergence point [t1].

[0048] 7 is a diagram (part 2) for explaining the standby period [D1] in the ink discharge inspection method according to the first embodiment. As shown in FIG 7, if the end point [t2] of the switching period [D2] is later than the convergence point [t1], the standby period [D1] may be set to the end point [t2] of the switching period [D2].

[0049] Moreover, the waiting period [D1], like the switching period [D2], includes the minimum interval between ink ejection from each nozzle.

[0050] In the above manner, when the state determination unit 24b-4 determines that the waiting period [D1] has ended (YES), the process proceeds to the next step S105.

[0051] <Step S105> In step S105, the head drive control unit 24b-1 detects the nozzle state by residual vibration for each nozzle 242 in the nozzle row for which it has been determined in step S104 that the waiting period [D1] has ended. At this time, in response to an instruction from the head drive control unit 24b-1, the nozzle drive unit 241a applies a test voltage for ink discharge testing as a pulse wave [p2] to each of the nozzles 242. The voltage value of this pulse [p2] has a preset magnitude, and may be a magnitude that causes ink to be discharged or may not cause ink to be discharged.

[0052] As a result, the state determination unit 24b-4 determines the ink ejection state of each nozzle 242 based on the residual waveform input to the signal input unit 24b-3. The state determination unit 24b-4 determines the ink ejection state, for example, by comparing the residual waveform obtained here with a normal waveform obtained from a normal nozzle in which the ink ejection state is normal. The comparison of the waveforms is, for example, a comparison of characteristic values ​​such as the waveform amplitude, period, bias level (average bias), attenuation rate, and phase.

[0053] The head drive control unit 24b-1 may select only the nozzles 242 that were used in image formation among the nozzles 242 in the nozzle row for which it has been determined in step S104 that the standby period [D1] has ended, and perform nozzle state detection based on residual vibration. For example, as shown in Fig. 3, the nozzles 242 located outside the image formation area Pa of the recording medium P in the transport width direction [y] do not eject ink during image formation. For this reason, these nozzles 242 may be configured not to perform nozzle state detection based on residual vibration.

[0054] 3, the head drive control unit 24b-1 performs nozzle state detection during the inspection period [D3] until the next image formation area Pa reaches the nozzle row after the waiting period [D1] ends. In other words, the nozzle state detection is performed when each nozzle 242 of the nozzle row is in a non-image formation period between the image formation period [D0] and the next image formation period [D0']. This nozzle row is the nozzle row for which the waiting period [D1] has been determined to have ended in step S104.

[0055] FIG. 8 is a diagram for explaining image formation including an ink ejection inspection method according to an embodiment. As shown in FIG. 8, the page change period [D13] (non-image formation period) is between the image formation period [D0] for the nth recording medium and the image formation period [D0'] for the next n+1th recording medium. The above-mentioned waiting period [D1] is set at the beginning of this page change period [D13]. Then, the remaining period of the page change period [D13] after the waiting period [D0] ends is the inspection period [D3]. During this inspection period [D3], the head drive control unit 24b-1 (see FIG. 4) performs nozzle state detection by residual vibration for each nozzle 242 of the nozzle row for which it is determined in step S104 that the waiting period [D1] has ended.

[0056] <Step S106> In step S106, the head drive controller 24b-1 stores the detection results of the nozzle state detection in step S105 for each nozzle 242, and ends the process.

[0057] The head drive control unit 24b-1 may display the detection result on the display unit 42 of the control device 40, and may perform automatic maintenance on nozzles where defective ink ejection has been found. Furthermore, the head drive control unit 24b-1 may be configured to form images in the subsequent image forming areas Pa by complementing the ink ejection from the nozzle where defective ink ejection has been found with ink ejection from other nozzles.

[0058] Effect of the First Embodiment As described above, the first embodiment is configured to perform the ink discharge inspection after the waiting period [D1] for converging the residual vibration [W2r] caused by the application of the drive voltage for image formation has elapsed. This prevents the residual vibration of the nozzle caused by the application of the drive voltage for image formation from being affected by the residual vibration [W2r] caused by the application of the drive voltage for image formation. As a result, the ink discharge state of each nozzle can be detected with high accuracy, and high-definition image formation by highly accurate ink discharge based on the detection results is possible.

[0059] -Second embodiment- Image forming device Fig. 9 is a block diagram of the main parts of an image forming apparatus 2 according to the second embodiment. The image forming apparatus 2 shown in Fig. 9 differs from the image forming apparatus of the first embodiment in that an ink head 241 has a temperature sensor 243, and a head drive control unit 24b-1 constituting an ink discharge inspection device makes a determination based on information from the temperature sensor 243. Other configurations are similar to those of the image forming apparatus of the first embodiment, so duplicated explanations will be omitted.

[0060] <Ink discharge inspection method> The ink discharge inspection method of the second embodiment differs from the ink discharge inspection method of the first embodiment described using the flowchart in Fig. 5 in the procedure of determining whether or not the waiting period [D1] has ended in step S104, while the other steps are similar. For this reason, the procedure of step S104 shown in Fig. 5 will be described with reference to Fig. 9 and other necessary figures.

[0061] <Step S104> In step S104, the state determination unit 24b-4 determines whether or not the standby period [D1] has ended for each nozzle 242 in the nozzle row that stopped ejecting ink in step S103, based on the temperature of the ink head 241 acquired from the temperature sensor 243. Here, the standby period [D1] is a period during which application of a drive signal for ink ejection inspection to the nozzle 242 is stopped after image formation is completed. Here, this standby period [D1] is the period until the temperature of each ink head 241 falls within a predetermined temperature range.

[0062] Fig. 10 is a diagram (part 1) for explaining the waiting period [D1] in the ink discharge inspection method according to the second embodiment, and is a diagram showing the temperature of each ink head 241 over time. As shown in Fig. 10, the temperature of each ink head 241-1 to 242-4 decreases over time from the discharge stop time [t0] when ink discharge from the nozzles 242 for image formation is stopped. Each ink head 241-1 to 242-4 is arranged in the transport width direction [y].

[0063] After ink ejection is stopped in step S103, the state determination unit 24b-4 determines that the standby period [D1] has ended (YES) at the convergence point [t1] at which the temperature of each ink head 241-1 to 242-4 detected by the temperature sensor 243 falls within a predetermined temperature range [R]. This temperature range [R] is set through a prior experiment as a range that does not affect the ink ejection inspection. This temperature range may also be a range that reflects the magnitude of temperature variation among the ink heads 241-1 to 242-4, and even in this case, it is set through a prior experiment.

[0064] Here, this waiting period [D1] includes a switching period [D2] required for signal processing to switch the drive signal for image formation to the drive signal for ink ejection inspection, as in the first embodiment. Therefore, if the end point [t2] of the switching period [D2] is earlier than the convergence point [t1], the waiting period [D1] may be set to the convergence point [t1].

[0065] 11 is a diagram (part 2) for explaining the standby period [D1] in the ink discharge inspection method according to the second embodiment. As shown in FIG. 11, if the end point [t2] of the switching period [D2] is later than the convergence point [t1], the standby period [D1] can be set to the end point [t2] of the switching period [D2], as in the first embodiment.

[0066] Furthermore, like the switching period [D2], the waiting period [D1] also includes the minimum interval between ink ejection from each nozzle, which is the same as in the first embodiment.

[0067] In the above manner, when the state determination unit 24b-4 determines that the waiting period [D1] has ended (YES), the process proceeds to the next step S105.

[0068] The determination in step S104 is performed for the nozzle rows that stopped ejecting ink in step S103. That is, for each of these nozzle rows, the state determination unit 24b-4 determines the end of the standby period [D1] based on the temperature of each of the ink heads 241-1 to 242-4 in which each nozzle row is provided.

[0069] Effect of the Second Embodiment As described above, the second embodiment is configured to perform the ink discharge inspection after the waiting period [D1] for the temperature change of the ink head caused by the application of the drive voltage for image formation to converge has passed. This prevents the temperature change of the ink head 241 caused by the application of the drive voltage for image formation from affecting the residual vibration of the nozzle caused by the application of the drive voltage for the ink discharge inspection. As a result, like the first embodiment, the ink discharge state of each nozzle can be detected with high accuracy, and high-definition image formation by highly accurate ink discharge becomes possible.

[0070] The second embodiment can be combined with the first embodiment. In this case, in step S104, when the residual vibration [W2r] caused by the application of the drive voltage for image formation has converged and the temperature change of the ink head has also converged, the state determination unit 24b-4 may determine that the waiting period [D1] has ended (YES). This allows the ink ejection state of each nozzle to be detected with even greater accuracy. [Explanation of symbols]

[0071] 1, 2...Image forming device 21... Media transport device 24a...Image data processing unit (ink discharge inspection device) 24b...Head drive processing unit (ink discharge inspection device) 24b-1: Head drive control section 24b-2...Head drive waveform generator 24b-3…Signal input section 24b-4…Status determination section 40...Control device 43...Control section 241,141-1~241-4…Ink head 242…Nozzle P…Recording medium [D0],[D0']...Image formation period [D1]…Waiting period [D2]…Transition period [D3]…Inspection period [W2r]…Residual vibration [W1]…Drive signal waveform [W2]…Vibration waveform [x]…Transport direction [x1]…Rotation direction [y]…Transport width direction

Claims

1. An ink discharge inspection device for inspecting an ink discharge state from a plurality of nozzles provided in an ink discharge device, comprising: a head drive control unit that applies a test voltage for ink ejection testing to each of the nozzles after an image formation period in which a drive voltage for image formation is applied to each of the nozzles has ended, and after a waiting period until the effect of application of the drive voltage to each of the nozzles has converged has ended; a state determination unit that determines an ink ejection state of each of the nozzles based on a residual vibration of each of the nozzles obtained by applying the test voltage. Ink discharge inspection device.

2. The head drive control unit includes: determining whether or not the standby period has ended for each of the nozzles based on the residual vibration of each of the nozzles obtained by applying the drive voltage; The inspection voltage is applied to the nozzles for which it is determined that the waiting period has ended among the nozzles. The ink discharge inspection device according to claim 1 .

3. The head drive control unit determines that the standby period has ended when an amplitude of residual vibration of each of the nozzles obtained by applying the drive voltage falls within a predetermined range. The ink discharge inspection device according to claim 2 .

4. The head drive control unit includes: determining whether the standby period has ended for each of the nozzles based on a temperature of the ink head in which the plurality of nozzles are provided; The inspection voltage is applied to the nozzles for which it is determined that the waiting period has ended among the nozzles. The ink discharge inspection device according to claim 1 .

5. The head drive control unit determines that the standby period has ended when the temperature of the ink head falls within a predetermined range. The ink discharge inspection device according to claim 4.

6. The head drive control unit determines that the standby period has ended when a variation in temperature among the ink heads, the image forming periods of which end substantially simultaneously, falls within a predetermined range. The ink discharge inspection device according to claim 4.

7. The waiting period includes a minimum interval between ink ejection from each of the nozzles. The ink discharge inspection device according to claim 1 .

8. The head drive control unit applies a test voltage for ink ejection testing to each of the nozzles during a non-image formation period between the image formation period and the next image formation period. The ink discharge inspection device according to claim 1 .

9. The waiting period includes a switching period required for a process of switching from the output waveform of the driving voltage to the output waveform of the inspection voltage. The ink discharge inspection device according to claim 1 .

10. The head drive control unit applies the inspection voltage to a selected nozzle from among the plurality of nozzles. The ink discharge inspection device according to claim 1 .

11. The front head drive control unit applies the inspection voltage to the nozzles in order starting from the nozzles for which the standby period has ended. The ink discharge inspection device according to claim 1 .

12. the ink ejection device has a plurality of nozzle rows in which a plurality of nozzles are arranged, The head drive control unit includes: The end of the standby period is determined and the test voltage is applied to nozzles of the nozzle rows that have completed the image forming period, in order, among the plurality of nozzle rows. The ink discharge inspection device according to claim 1 .

13. An ink ejection inspection method for inspecting an ink ejection state from a plurality of nozzles provided in an ink ejection device, comprising: a head drive control unit applies a test voltage for ink ejection testing to each of the nozzles after an image formation period during which a drive voltage for image formation is applied to each of the nozzles has ended and after a waiting period during which an effect of the application of the drive voltage to each of the nozzles has converged has ended; A state determination unit determines an ink ejection state of each of the nozzles based on a residual vibration of each of the nozzles obtained by applying the test voltage. Ink ejection inspection method.

14. An ink ejection inspection program for causing a computer to inspect an ink ejection state from a plurality of nozzles provided in an ink ejection device, comprising: After an image forming period during which a drive voltage for image formation is applied to each of the nozzles has ended, and after a waiting period until the effect of the application of the drive voltage to each of the nozzles has converged has ended, a test voltage for ink discharge test is applied to each of the nozzles. The ink ejection state of each of the nozzles is determined based on the residual vibration of each of the nozzles obtained by applying the test voltage. Ink ejection inspection program.

15. an ink head provided with a plurality of nozzles that eject ink when a voltage is applied; An ink discharge inspection device according to any one of claims 1 to 12. Ink ejection device.

16. The ink head has a configuration in which the plurality of nozzles are arranged in at least one direction. The ink ejection device according to claim 15.

17. The ink head has a plurality of head units arranged in one direction.

17. The ink ejection device according to claim 16.

18. The ink ejection device according to claim 15, a medium transport device that transports a recording medium on which an image is formed by the ink ejected from the plurality of nozzles in the ink ejection device in a predetermined transport direction relative to the ink ejection device. Image forming device.

19. The plurality of nozzles in the ink ejection device are arranged in a conveyance width direction perpendicular to a conveyance direction of the recording medium.

20. The image forming apparatus according to claim 18.

20. A plurality of nozzle rows, in which the plurality of nozzles are arranged across the transport width direction, are arranged in the transport direction.

20. The image forming apparatus according to claim 19.

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