Ejection abnormality inspection device, inkjet recording apparatus, ejection abnormality inspection method, and program

Abstract

To provide a discharge abnormality inspection device, an inkjet recording device, a discharge abnormality inspection method, and a program capable of more accurately detecting occurrence of a discharge bending nozzle.SOLUTION: The controller 40 of the ejection abnormality inspection device functions as a determination unit that determines the presence or absence of a deflected ejection nozzle in the inkjet head based on the number of missing nozzles in the inkjet head acquired from the waveform of the residual vibration of the nozzle in the inkjet head and the number of white stripes WS from the read data of the image formed on the recording medium P.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an ejection abnormality inspection device, an inkjet recording device, an ejection abnormality inspection method, and a program. [Background technology]

[0002] Conventionally, inkjet recording devices are known that eject ink from the nozzles of an inkjet head to record an image on a recording medium. In inkjet recording devices, if the nozzle surface is scratched or foreign matter adheres to the nozzle, the nozzle's ejection angle can become misaligned. If the nozzle's ejection angle misaligns beyond a predetermined tolerance, resulting in a misaligned nozzle, ink will not be ejected where it should, resulting in white streaks in the image. Furthermore, if ink ejected from a misaligned nozzle overlaps with ink ejected from other nozzles on the recording medium, high-density streaks (color streaks) will appear in the image. When these abnormal streaks appear in an image, image quality will be reduced. Therefore, if a misaligned nozzle occurs, it is necessary to accurately detect it.

[0003] Therefore, for example, Patent Document 1 describes an inkjet recording device that detects deflected ejection nozzles by printing a chart image on a recording medium, reading it with an image reading unit, and detecting density differences in the read image. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-044308 Summary of the Invention [Problem to be solved by the invention]

[0005] However, for example, if the ink being ejected is yellow ink, the difference in density between the color streaks and other areas is small, and even if there is a nozzle with a deflected ejection, the color streaks may not be detected. Furthermore, white streaks can occur not only due to a nozzle with a deflected ejection, but also due to a missing nozzle that can no longer eject ink. Therefore, the invention of Patent Document 1 may not be able to accurately detect the occurrence of a nozzle with a deflected ejection.

[0006] The present invention has been made in view of the above circumstances, and its object is to provide an abnormal discharge inspection device, an inkjet recording device, an abnormal discharge inspection method, and a program that can more accurately detect the occurrence of deflected discharge nozzles. [Means for solving the problem]

[0007] In order to solve the above problem, the invention described in claim 1 is a discharge abnormality inspection device, The inkjet head is provided with a determination unit that determines whether or not the inkjet head has deflected nozzles based on the number of missing nozzles of the inkjet head obtained from the waveform of residual vibration of the nozzles of the inkjet head and the number of white streaks obtained from the read data of an image formed on a recording medium.

[0008] The invention described in claim 2 is the ejection abnormality inspection device described in claim 1, The determination unit determines that there are no deflected ejection nozzles when the number of missing nozzles and the number of white streaks are the same, and determines that there are deflected ejection nozzles when the number of missing nozzles and the number of white streaks are different.

[0009] The invention described in claim 3 is the ejection abnormality inspection device described in claim 2, When the number of white streaks is greater than the number of missing nozzles, the determining unit determines that there is a deflected ejection nozzle.

[0010] The invention described in claim 4 is the ejection abnormality inspection device described in claim 1, The nozzle control unit includes a specifying unit that specifies whether any of the nozzles is the missing nozzle or the deflected ejection nozzle.

[0011] The invention described in claim 5 is the ejection abnormality inspection device described in claim 4, When the determining unit determines that there is a nozzle with deflected ejection, the identifying unit forms a test image to identify which nozzle is the deflected ejection nozzle.

[0012] The invention described in claim 6 is the ejection abnormality inspection device described in claim 1, The image is a job image.

[0013] The invention described in claim 7 is an inkjet recording apparatus, an image forming unit that forms an image on a recording medium by ejecting ink droplets from an inkjet head; an image reading unit that reads the image formed on the recording medium to obtain the read data; and the ejection abnormality inspection device according to any one of claims 1 to 6.

[0014] The invention described in claim 8 is the inkjet recording apparatus described in claim 7, The nozzle includes a missing correction unit that performs missing correction for the missing nozzle when the determination unit determines that there is no nozzle with deflected ejection.

[0015] The invention described in claim 9 is a method for inspecting an abnormal discharge, comprising: an image forming unit that forms an image on a recording medium by ejecting ink droplets from an inkjet head; an image reading unit that reads the image formed on the recording medium, The method includes a determination step for determining whether or not the inkjet head has deflected nozzles based on the number of missing nozzles of the inkjet head obtained from the waveform of residual vibration of the nozzles of the inkjet head and the number of white streaks obtained from the read data of the image formed on the recording medium.

[0016] The invention described in claim 10 is a program, an image forming unit that forms an image on a recording medium by ejecting ink droplets from an inkjet head; an image reading unit that reads the image formed on the recording medium; The device functions as a determination unit that determines whether or not the inkjet head has deflected nozzles based on the number of missing nozzles of the inkjet head obtained from the waveform of residual vibration of the nozzles of the inkjet head and the number of white streaks obtained from the read data of the image formed on the recording medium. [Effects of the Invention]

[0017] According to the present invention, occurrence of deflected ejection nozzles can be detected more accurately. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a side view of the inkjet recording apparatus as seen from the width direction. [Figure 2] FIG. 2 is a block diagram of a main part of the inkjet recording apparatus. [Figure 3] 10 is a graph comparing the residual vibration waveform of a normal ejection nozzle with the residual vibration waveform of a defective nozzle. [Figure 4] 10 is a graph comparing the residual vibration waveform of a normal ejection nozzle with the residual vibration waveform of a deflected ejection nozzle. [Figure 5] 10 is an example of an image having abnormal streaks. [Figure 6] 10 is a flowchart of a process for detecting deflected ejection nozzles. DETAILED DESCRIPTION OF THE INVENTION

[0019] An inkjet recording apparatus equipped with an ejection abnormality inspection device according to an embodiment of the present invention will be described in detail below with reference to the drawings. However, the scope of the invention is not limited to the illustrated example. In the following description, components having the same functions and configurations will be assigned the same reference numerals and their description will be omitted.

[0020] [Overall configuration of inkjet recording device] Fig. 1 is a side cross-sectional view showing the main configuration of an inkjet recording apparatus 1. Fig. 2 is a block diagram showing a partial functional configuration of the inkjet recording apparatus 1. The inkjet recording apparatus 1 includes a paper feed unit 10, an image forming unit 20, a paper discharge unit 30, and a control unit 40.

[0021] (Paper feed section) The paper feed unit 10 stores recording media P before image formation. The paper feed unit 10 transports the recording media P to the image forming unit 20 under the control of the control unit 40. The paper feed unit 10 includes a paper feed tray 11, a transport unit 12, and the like.

[0022] {Paper feed tray} The paper feed tray 11 is a plate-like member that stores recording media P. The paper feed tray 11 is provided so that one or more recording media P can be placed on it. The paper feed tray 11 moves up and down depending on the amount of recording media P placed on it. By this up and down movement, the paper feed tray 11 is held at a position where the top recording medium P can be transported by the transport unit 12.

[0023] {Transportation section} The conveying unit 12 conveys the recording medium P from the paper feed tray 11 to the image forming unit 20. The conveying unit 12 includes a conveying mechanism. The conveying mechanism drives a belt 123 to convey the recording medium P on the belt 123. The belt 123 is ring-shaped, and the inside of the ring is supported by a plurality of rollers 121 and 122.

[0024] The conveying unit 12 includes a supply unit. The supply unit delivers the top recording medium P placed on the paper feed tray 11 onto the belt 123. The conveying unit 12 conveys the recording medium P along the belt 123 by the supply unit.

[0025] (Image forming section) The image forming unit 20 performs a recording operation on the recording medium P under the control of the control unit 40. The image forming unit 20 includes an image forming drum 21, a delivery unit 22, a paper heating unit 23, a head unit 24, an irradiation unit 25, an image reading unit 26, a delivery unit 27, and the like.

[0026] {Image forming drum} The image forming drum 21 carries the recording medium P along its cylindrical outer circumferential surface and transports the recording medium P as it rotates. The transport surface of the image forming drum 21 faces the paper heating unit 23, the head unit 24, and the irradiation unit 25, and performs an image forming process on the transported recording medium P.

[0027] {Delivery unit} The delivery unit 22 is provided at a position interposed between the transport section 12 and the image forming drum 21. The delivery unit 22 includes a claw portion 221, a delivery drum 222, and the like.

[0028] The claw portion 221 is a cylindrical member that holds one end of the recording medium P conveyed by the conveying unit 12. The delivery drum 222 is a member that guides the recording medium P held by the claw portion 221.

[0029] The delivery unit 22 picks up the recording medium P on the conveying section 12 with the claw portion 221 and moves it along the outer circumferential surface of the delivery drum 222. The delivery unit 22 delivers the recording medium P to the image forming drum 21 by this operation.

[0030] {Paper heating section} The paper heating unit 23 includes, for example, an electric heating wire, and generates heat in response to the passage of electricity. The paper heating unit 23 is controlled by the control unit 40, and generates heat so that the recording medium P passing nearby reaches a predetermined temperature. The paper heating unit 23 is located near the outer circumferential surface of the image forming drum 21 and is positioned upstream of the head unit 24 in the conveyance direction of the recording medium P.

[0031] A temperature sensor (not shown) is provided near the paper heating unit 23. The control unit 40 uses the temperature sensor to detect the temperature near the paper heating unit 23. The control unit 40 controls the heat generation of the paper heating unit 23 based on the detected temperature.

[0032] {Head Unit} The head unit 24 forms an image by ejecting ink onto the recording medium P based on, for example, a print job and image data received from an external device 2 described below. The head units 24 are provided corresponding to the colors C (cyan), M (magenta), Y (yellow), and K (black). In FIG. 1, the head units 24 corresponding to the colors Y, M, C, and K are provided in this order from upstream in the conveyance direction of the recording medium P.

[0033] The head unit 24 of this embodiment is configured with a carriage and multiple inkjet heads arranged in the width direction. Each inkjet head includes a color ink tank, a flow path, a piezoelectric element, and multiple nozzles. The control unit 40 applies a drive signal generated by a drive unit (not shown) to displace (deform) the piezoelectric element, applying pressure to the color ink supplied from the tank to the nozzle via the flow path, causing the ink to be ejected from the nozzle.

[0034] The head unit 24 forms an image by ejecting ink onto the conveyed recording medium P from a carriage whose width is longer than the recording medium P. In other words, the inkjet recording device 1 is a line head type inkjet recording device. The number of head units 24 provided in the image forming section 20 may be three or less, or five or more.

[0035] The ink ejected by the head unit 24 is, for example, ultraviolet curable ink. The ultraviolet curable ink is a gel ink that changes phase between a gel state and a liquid (sol) state depending on the temperature when not irradiated with ultraviolet light from the irradiation unit 25. The sol-gel phase transition temperature of the ultraviolet curable ink is preferably within a range of 40 to 70°C, and more preferably within a range of 50 to 65°C.

[0036] {Irradiation unit} The irradiation unit 25 includes, for example, a fluorescent tube such as a low-pressure mercury lamp. The irradiation unit 25 emits energy rays such as ultraviolet light by emitting light from the fluorescent tube. The irradiation unit 25 is provided near the outer circumferential surface of the image forming drum 21. The irradiation unit 25 is also provided so as to be located downstream of the head unit 24 in the transport direction of the recording medium P. The irradiation unit 25 irradiates the recording medium P onto which ink has been ejected with energy rays. The ink on the recording medium P is cured by the action of the energy rays.

[0037] The fluorescent tube that emits ultraviolet light is not limited to a low-pressure mercury lamp. The fluorescent tube may be a mercury lamp with an operating pressure of, for example, several hundred Pa to 1 MPa. The fluorescent tube may also be a light source that can be used as a germicidal lamp, such as a cold cathode tube, an ultraviolet laser light source, a metal halide lamp, or a light-emitting diode. Among these, it is preferable that the fluorescent tube is a light source that can irradiate ultraviolet light with higher illuminance and is energy-saving. The fluorescent tube is, for example, a light-emitting diode. The energy rays are not limited to ultraviolet light, and may be energy rays that have the property of curing ink depending on the properties of the ink. The light source is also replaced depending on the energy rays.

[0038] Although the above example illustrates a case where the head unit 24 ejects ultraviolet curable ink, the present invention is not limited to this. The ink ejected by the head unit 24 may be water-based ink or other inks.

[0039] {Image reading unit} The image reading unit 26 is disposed downstream in the transport direction from the irradiation unit 25 so as to be able to read the image forming surface, which is the surface of the recording medium P. The image reading unit 26 is, for example, a line sensor. The image reading unit 26 reads the image forming surface of the recording medium P within a predetermined reading range and transmits the captured image data to a read image acquisition unit 45 (described later) of the control unit 40.

[0040] {Delivery Department} The delivery unit 27 includes a transport mechanism. The transport mechanism drives a ring-shaped belt 273, the inside of which is supported by a plurality of rollers 271 and 272, to transport the recording medium P. The delivery unit 27 includes a cylindrical delivery roller 274. The delivery roller 274 delivers the recording medium P from the image forming drum 21 to the transport mechanism. The delivery unit 27 transports the recording medium P delivered onto the belt 273 by the delivery roller 274, and sends it out to the paper discharge unit 30.

[0041] (Paper ejection section) The paper discharge section 30 discharges the recording medium P on which an image has been formed in the image forming section 20 . The paper discharge unit 30 includes a plate-shaped paper discharge tray 31. The recording medium P sent out from the image forming unit 20 by the delivery unit 27 is placed on the paper discharge tray 31. The paper discharge unit 30 stores the recording medium P until the user removes it.

[0042] (Control unit) The control unit 40 controls each unit constituting the inkjet recording apparatus 1. The control unit 40 is connected to each unit constituting the inkjet recording apparatus 1. The control unit 40 includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc.

[0043] The CPU reads out various programs, data, etc. corresponding to the processing content from a storage device such as a ROM and executes them. The CPU controls the operation of each part of the inkjet recording device 1 according to the processing content executed. The RAM temporarily stores various programs, data, etc. processed by the CPU. The ROM is a non-volatile storage device such as an HDD (Hard Disk Drive), SSD (Solid State Drive) or flash memory, and stores various programs, data, etc. read out by the CPU, etc.

[0044] The control unit 40, through cooperation of the CPU, RAM, and ROM, functions as a residual vibration waveform acquisition unit 41, a residual vibration waveform determination unit 43, a read image acquisition unit 45, a read image determination unit 46, a determination result comparison unit 47, and a missing portion correction unit 48. Of these, at least the residual vibration waveform acquisition unit 41, the residual vibration waveform determination unit 43, the read image acquisition unit 45, and the determination result comparison unit 47 cause the control unit 40 to function as a discharge abnormality inspection device.

[0045] {Residual vibration waveform acquisition section} The residual vibration waveform acquisition unit 41 detects the residual vibration after ink ejection and acquires the waveform, which is the residual vibration waveform. As described above, when a drive waveform is applied to a piezoelectric element, the piezoelectric element deforms, pressure is applied to the ink, and the ink is ejected from the nozzle. At this time, residual pressure vibration occurs in the ink, which propagates to the piezoelectric element and induces a residual vibration voltage. The residual vibration waveform acquisition unit 41 detects the residual vibration voltage and transmits the waveform to the residual vibration waveform determination unit 43.

[0046] {Residual vibration waveform determination section} The residual vibration waveform determination unit 43 compares the residual vibration waveform acquired from the residual vibration waveform acquisition unit 41 with the residual vibration waveform of a normal ejection nozzle stored in advance in a ROM or the like to determine whether the nozzle from which the residual vibration waveform acquisition unit 41 acquired the residual vibration waveform is a defective nozzle. Through this process, the residual vibration waveform determination unit 43 acquires the number of defective nozzles. Note that a defective nozzle refers to a nozzle that is no longer able to eject ink (has experienced an ejection defect) due to clogging caused by ink adhering and solidifying in the nozzle, for example. Furthermore, through this process, the residual vibration waveform determination unit 43 functions as an identification unit that identifies which nozzles are defective.

[0047] Figure 3 shows the drive waveforms and residual vibration waveforms of a defective nozzle and a normally ejecting nozzle side by side. In Figure 3, the horizontal axis represents time and the vertical axis represents voltage. Also in Figure 3, W10 represents the drive waveform, W20A represents the residual vibration waveform of a normally ejecting nozzle, and W20B represents the residual vibration waveform of the defective nozzle. As shown in Figure 3, there is a large difference in amplitude between the residual vibration waveform of a defective nozzle and the residual vibration waveform of a normally ejecting nozzle. For this reason, the residual vibration waveform determination unit 43 can detect defective nozzles by acquiring the residual vibration waveform from the nozzle.

[0048] Figure 4 also shows the drive waveforms and residual vibration waveforms of a nozzle (deflected ejection nozzle) in which the ink ejection angle has shifted due to scratches on the nozzle surface or foreign matter adhering to the nozzle, and a normal ejection nozzle. In Figure 4, W20C shows the residual vibration waveform of a deviated ejection nozzle. As shown in Figure 4, there is only a slight difference between the residual vibration waveforms of a deviated ejection nozzle and a normal ejection nozzle. For this reason, it is difficult to detect a deviated ejection nozzle based on the residual vibration waveform.

[0049] {Read image acquisition section} The read image acquisition unit 45 acquires read data of the image formed on the recording medium P from the image reading unit 26.

[0050] {Read image determination section} The read image determination unit 46 compares the read data acquired by the read image acquisition unit 45 with, for example, image data, to acquire the number of white streaks WS.

[0051] Figure 5 shows an example of scanned data with abnormal streaks highlighted. As shown in Figure 5, there are two types of abnormal streaks: white streaks WS and colored streaks CS. White streaks WS are formed when ink is not ejected from a nozzle that should have ejected ink to that location. In other words, white streaks WS are formed by both deflected ejection nozzles and missing nozzles. On the other hand, colored streaks CS are formed when ink is ejected from a nozzle that should not have ejected ink to that location. In other words, colored streaks CS are formed only by deflected ejection nozzles.

[0052] {Decision result collation section} The determination result collating unit 47 is a determining unit that determines the presence and number of missing nozzles and deflected ejection nozzles by collating the determination results of the residual vibration waveform determining unit 43 and the read image determining unit 46 .

[0053] In detail, as described above, the judgment result comparison unit 47 can obtain the presence or absence of missing nozzles and the number thereof from the judgment result of the residual vibration waveform judgment unit 43. Furthermore, the judgment result comparison unit 47 can determine the presence or absence of deflected ejection nozzles and the number thereof by comparing the judgment result of the residual vibration waveform judgment unit 43 with the judgment result of the read image judgment unit 46.

[0054] More specifically, when determining whether or not there are deflected nozzles and the number of deflected nozzles, the determination result comparison unit 47 compares the number of defective nozzles obtained from the residual vibration waveform determination unit 43 with the number of white streaks WS obtained from the read image determination unit 46. As described above, white streaks WS are formed by both deflected nozzles and defective nozzles. Therefore, if the number of white streaks WS obtained from the read image determination unit 46 is the same as the number of defective nozzles obtained from the residual vibration waveform determination unit 43, the determination result comparison unit 47 can determine that all of the white streaks WS are formed by defective nozzles and that there are no deflected nozzles. On the other hand, if the number of white streaks WS obtained from the read image determination unit 46 is greater than the number of defective nozzles obtained from the residual vibration waveform determination unit 43, the determination result comparison unit 47 can determine that the difference between the two is the number of deflected nozzles.

[0055] {Missing correction part} When the missing nozzle is detected, the missing nozzle correction unit 48 performs a missing nozzle correction process to prevent image defects (white streaks WS) caused by the missing nozzle. The missing nozzle correction process complements the image data by, for example, adjusting the amount of ink ejected from the nozzles around the missing nozzle or adjusting the ejection position.

[0056] (Notification Department) The notification unit 50 notifies various pieces of information under the control of the control unit 40. While Fig. 1 illustrates an example in which the notification unit 50 is a display unit having a screen, the notification unit 50 is not limited to this. The notification unit 50 may also be a speaker that emits sound, a communication unit that can communicate with other devices via a predetermined network, or the like.

[0057] (external device) The external device 2 is a device separate from the inkjet recording device 1. The external device 2 supplies the control unit 40 with print jobs, image data, and the like.

[0058] [Detection of deflected nozzles] The process of detecting deflected ejection nozzles in the inkjet recording apparatus 1 will be described with reference to the flowchart of FIG.

[0059] Upon receiving a print job and image data from the external device 2, the control unit 40 drives the head unit 24 to form an image on the recording medium P (step S101).

[0060] After image formation, the residual vibration waveform acquisition unit 41 acquires the residual vibration waveform from each nozzle and transmits it to the residual vibration waveform determination unit 43 (step S102). The residual vibration waveform determination unit 43 acquires the number of missing nozzles based on the acquired residual vibration waveform (step S103).

[0061] Then, the recording medium P on which the image is formed passes through the image reading unit 26, and the read image obtaining unit 45 obtains read data (step S104). The read image determining unit 46 compares the read data with the image data to obtain the number of white streaks WS (step S105).

[0062] The read image determination unit 46 determines whether or not there is a white streak WS (step S106). If there is no white streak WS (step S106; No), no abnormal nozzle has occurred. Therefore, the control unit 40 ends the deflected ejection nozzle detection process.

[0063] If a white streak WS is present (step S106; Yes), an abnormal nozzle has occurred. Therefore, the judgment result collation unit 47 acquires the breakdown of the abnormal nozzle by acquiring the judgment results from the residual vibration waveform judgment unit 43 and the read image judgment unit 46.

[0064] The determination result comparison unit 47 determines whether the number of missing nozzles acquired by the residual vibration waveform determination unit 43 in step S103 is the same as the number of white streaks WS acquired by the read image determination unit 46 in step S105 (step S107). If the number of missing nozzles and the number of white streaks WS are the same (step S107; Yes), all of the abnormal nozzles are missing nozzles. Therefore, the missing nozzle correction unit 48 performs the missing nozzle correction process described above on the missing nozzles from which the residual vibration waveform was acquired (step S108). The notification unit 50 notifies the user of the presence of a missing nozzle, and the deflected ejection nozzle detection process ends.

[0065] If the number of missing nozzles is different from the number of white streaks WS (step S107; No), that is, if the number of white streaks WS is greater than the number of missing nozzles, then there are nozzles with deflected ejection corresponding to the difference. The control unit 40 can identify which nozzles are missing nozzles from the source of the residual vibration waveform, but cannot identify which nozzles are deflected ejection nozzles. Therefore, the control unit 40 determines which nozzles are deflected ejection nozzles by having the head unit 24 form a test image (step S109).

[0066] After identifying which nozzle is a deflected discharge nozzle, the control unit 40 masks the deflected discharge nozzle, and then proceeds to step S108, where the defect correction unit 48 performs defect correction processing in the same way as for a missing nozzle. The notification unit 50 then notifies the user of the presence of the missing nozzle and the deflected discharge nozzle, and the deflected discharge nozzle detection process ends.

[0067] [Effects of the embodiment] As described above, in this embodiment, the determination result collation unit 47 functions as a determination unit that determines the presence or absence of deflected ejection nozzles based on the number of missing nozzles obtained from the waveform of residual vibration of the nozzles of the inkjet head and the number of white streaks WS obtained from the read image data. With this configuration, even if the color streaks CS are not of a detectable density, the occurrence of deflected ejection nozzles can be detected more accurately because the color streaks CS are not used to detect the occurrence of deflected ejection nozzles.

[0068] Furthermore, as described above, the control unit 40 can execute the abnormal discharge inspection process while forming a job image through the normal image formation process. Therefore, if there is no deflected discharge nozzle, there is no need to perform special processing, and the productivity of image formation does not decrease.

[0069] [Other configurations] Although the present invention has been specifically described above based on the embodiments thereof, the present invention is not limited to the above-described embodiments. Of course, the present invention can be modified in various ways within the scope of the invention described in the claims and its equivalents.

[0070] For example, in the above example, a configuration in which a print job and image data are received from the external device 2 is exemplified, but this is not limiting. For example, the inkjet recording apparatus 1 may be equipped with a known operation input unit, scanner, etc., and the print job and image data may be directly input by the user.

[0071] In addition, although the inkjet recording apparatus 1 is illustrated above as having a line-head type image forming unit 20, this is not limiting. The image forming unit 20 may be a serial-head type that forms an image by scanning a carriage 242, whose width is shorter than that of the recording medium P, in the width direction. In this configuration, abnormal streaks may be formed in the width direction.

[0072] In addition, in the above description, the residual vibration waveform of a defective nozzle and the residual vibration waveform of a normally ejecting nozzle are said to have significantly different amplitudes, but this is not limited to this. The residual vibration waveform of a defective nozzle and the residual vibration waveform of a normally ejecting nozzle may also have significantly different amplitude periods.

[0073] In the above, the residual vibration waveform is acquired during image formation, but this is not limiting. For example, the residual vibration waveform may be acquired by applying a minute voltage that does not cause ink droplets to be ejected from the nozzles between sheets of recording medium P.

[0074] Furthermore, in the above example, the control unit 40 of the inkjet recording apparatus 1 functions as the ejection abnormality inspection device, but this is not limiting. That is, a PC or the like separate from the inkjet recording apparatus 1 may function as the residual vibration waveform acquisition unit 41, the residual vibration waveform determination unit 43, the read image acquisition unit 45, the read image determination unit 46, and the determination result comparison unit 47, thereby functioning as the ejection abnormality inspection device.

[0075] Although the above describes an example in which a hard disk or a semiconductor nonvolatile memory is used as a ROM as a computer-readable medium for the program according to the present invention, the present invention is not limited to this example. Other computer-readable media include portable recording media such as CD-ROMs. Furthermore, carrier waves are also applicable as a medium for providing the program data according to the present invention via a communication line. [Explanation of symbols]

[0076] 1. Inkjet recording device 20 Image forming unit 26 Image reading unit 40 control unit (discharge abnormality inspection device, identification unit) 43 Residual vibration waveform determination section (specification section) 47 Judgment result collation unit (judgment unit) 48 Missing part correction section P Recording medium

Claims

1. An abnormal ejection inspection device including a determination unit that determines whether or not the inkjet head has deflected ejection nozzles based on the number of missing nozzles of the inkjet head obtained from the waveform of residual vibration of the nozzles of the inkjet head and the number of white streaks obtained from read data of an image formed on a recording medium.

2. 2. The abnormal discharge inspection device according to claim 1, wherein the determination unit determines that there is no nozzle with deflected discharge when the number of missing nozzles and the number of white streaks are the same, and determines that there is a nozzle with deflected discharge when the number of missing nozzles and the number of white streaks are different.

3. 3. The abnormal discharge inspection device according to claim 2, wherein the determination unit determines that there is a nozzle with a deviated discharge when the number of white streaks is greater than the number of defective nozzles.

4. The abnormal discharge inspection device according to claim 1 , further comprising a specifying unit for specifying whether any of the nozzles is the defective nozzle or the deflected discharge nozzle.

5. 5. The abnormal discharge inspection device according to claim 4, wherein, when the determination unit determines that there is a nozzle with deflected discharge, the identification unit forms a test image to identify which nozzle is the deflected discharge nozzle.

6. The ejection abnormality inspection device according to claim 1 , wherein the image is a job image.

7. an image forming unit that forms an image on a recording medium by ejecting ink droplets from an inkjet head; an image reading unit that reads the image formed on the recording medium to obtain the read data; An inkjet recording apparatus comprising: the ejection abnormality inspection device according to claim 1 .

8. The inkjet recording apparatus according to claim 7 , further comprising a missing nozzle correction unit that performs missing nozzle correction for the missing nozzle when the determination unit determines that there is no deflected ejection nozzle.

9. an image forming unit that forms an image on a recording medium by ejecting ink droplets from an inkjet head; an image reading unit that reads the image formed on the recording medium, An abnormal ejection inspection method comprising a determination step of determining whether or not the inkjet head has deflected ejection nozzles based on the number of missing nozzles of the inkjet head obtained from a waveform of residual vibration of the nozzles of the inkjet head and the number of white streaks obtained from read data of an image formed on a recording medium.

10. an image forming unit that forms an image on a recording medium by ejecting ink droplets from an inkjet head; an image reading unit that reads the image formed on the recording medium; A program that functions as a determination unit that determines whether or not the inkjet head has deflected nozzles based on the number of missing nozzles of the inkjet head obtained from the waveform of residual vibration of the nozzles of the inkjet head and the number of white streaks obtained from the read data of an image formed on a recording medium.

Images