JP2014079979A - Recorder and discharge failure detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recorder capable of detecting a discharge failure with high accuracy without requiring a specified area for a preliminary discharge of a recording head, and the method thereof.SOLUTION: Preliminary discharge data for preliminary discharge and image recording data for image recording are inputted for comparison during recording by a recording head, and whether ink discharge from the recording head by these data are overlapped on the same position is determined. In the case that the ink discharge by the data is overlapped on the same position according to the determination, an output of the preliminary discharge data is delayed. Next, preliminary discharge is performed by the recording head with preliminary discharge data stored in a register, or the delayed preliminary discharge data, and the position of the preliminary discharge is stored in a memory. After that, a CIS sensor provided closer to a downstream side about the conveyance direction of a recording medium than the position of the preliminary discharge reads dots formed on the recording medium by the preliminary discharge, and whether a nozzle performing the preliminary discharge is a normal nozzle or a defective nozzle is determined according to the result.

Description

  The present invention relates to a recording apparatus and an ejection failure detection method, and more particularly to a recording apparatus including a full line recording head that performs recording in accordance with an ink jet method and an ejection failure detection method used in the apparatus.

  2. Description of the Related Art An ink jet recording apparatus (hereinafter referred to as a recording apparatus) that performs recording using a conventional ink jet recording head (hereinafter referred to as a recording head) supplies ink from an ink tank that stores ink to the recording head via an ink supply path. Ink is ejected using various recording methods. In such an apparatus, in order to form a high-quality image, the ink ejection amount, ejection speed, ejection direction, and the shape (volume) of the ejected ink are stably ejected so as to be always constant. There is a need to.

  In order to support high-speed recording, the recording head nozzles are always filled with ink so that recording is executed as soon as a recording instruction is given. The ink in the nozzles is exposed to the air through the ejection openings. Yes. For this reason, when ejection is not performed for a long time, volatile components evaporate from the ink of the nozzle, the ink viscosity becomes high and ink droplets cannot be ejected properly, or the nozzle is clogged, resulting in ejection failure. There are things to do. In addition, bubbles mixed in the ink supply path or the like may accumulate, and the ink supply may be interrupted or the ink may be ejected for a long time, resulting in a delay in ink refilling and ejection failure.

  Due to these various causes, ejection failure occurs or stable ink ejection cannot be performed, or in order to prevent the occurrence of these, it is necessary to perform recording head maintenance. Accordingly, various techniques have been proposed in the past for detecting whether or not ink is stably ejected and whether or not ejection failure has occurred in the recording head.

  For example, there is a technique for recording a predetermined test pattern on a recording sheet from a recording head having a plurality of nozzles at a predetermined resolution, and reading this with a scanner at a resolution lower than the recording resolution to determine nozzle abnormality based on the interpolation processing. Known (for example, Patent Document 1).

  Further, there is a technique for recording a chart composed of a graphic for detecting individual nozzles, a graphic for specifying a detection start position, and a graphic for specifying a detection reference position on a conveying belt for conveying a recording medium by a recording head. Known (for example, Patent Document 2).

JP 2006-240232 A JP 2009-274317 A

  However, the technique as proposed in Patent Document 1 records a test pattern at a predetermined position on a recording sheet, and therefore requires a dedicated area for the pattern, so that it can be used from the viewpoint of using paper for image recording. There was a problem of reducing efficiency.

  Further, the technique proposed in Patent Document 2 records a chart for detecting ejection failure at a predetermined position on a conveying belt that conveys a recording sheet, and thus a dedicated area for the chart is also required. There has been a problem of reducing the efficiency of image recording.

  The present invention has been made in view of the above-described conventional example, and can detect a discharge defect with high accuracy without requiring a specific area for preliminary discharge for detecting a discharge defect of a recording head. An object of the present invention is to provide a printing apparatus and a discharge failure detection method.

  In order to achieve the above object, the recording apparatus of the present invention has the following configuration.

  That is, a recording apparatus that records an image on the recording medium by transporting the recording medium in a predetermined direction and ejecting ink from a plurality of nozzles of the recording head, wherein the recording head performs preliminary ejection. A register for storing preliminary ejection data, a buffer memory for storing image recording data for recording an image by the recording head, a conveying means for conveying the recording medium, and during recording by the recording head The preliminary ejection data from the register and the image recording data from the buffer memory are inputted and compared, and whether the preliminary ejection data and the ink ejection from the recording head by the image recording data overlap at the same position A determination means for determining whether the preliminary ejection data and the image recording data are determined by the determination means; Therefore, when the ink ejection from the recording head overlaps at the same position, the delay means for delaying the output of the preliminary ejection data and the preliminary ejection data stored in the register or delayed by the delay means Pre-discharge means for executing pre-discharge of the recording head based on the pre-discharge data, storage means for storing the pre-discharge position executed by the pre-discharge means, and conveyance of the recording medium from the pre-discharge position. A reading unit that is provided on the downstream side with respect to the direction and reads the dots formed on the recording medium by the preliminary discharge, and whether the nozzle that has performed the preliminary discharge is a normal nozzle according to the result of reading by the reading unit Or it has the discrimination means which discriminate | determines whether it is a defective nozzle.

  In another aspect of the present invention, ejection failure detection of a recording apparatus that records an image on the recording medium by transporting the recording medium in a predetermined direction and ejecting ink from a plurality of nozzles of the recording head. A method, wherein during recording by the recording head, preliminary ejection data from a register storing preliminary ejection data for performing preliminary ejection by the recording head and image recording for recording an image by the recording head Judgment of inputting and comparing the image recording data from the buffer memory for storing the data for determining whether or not the preliminary ejection data and the ink ejection from the recording head by the image recording data overlap at the same position And the preliminary ejection data and the image recording data from the recording head based on the determination in the determination step. When the ink discharge overlaps at the same position, the delay process for delaying the output of the preliminary discharge data, the preliminary discharge data stored in the register, or the preliminary discharge data delayed in the delay process A preliminary ejection step for performing preliminary ejection from the recording head, a storage step for storing the preliminary ejection position executed in the preliminary ejection step in a memory, and a downstream side of the preliminary ejection position with respect to the conveyance direction of the recording medium. A reading step of reading dots formed on the recording medium by the preliminary discharge, and a nozzle that has performed the preliminary discharge is a normal nozzle according to a result of reading in the reading step, or And a determination step for determining whether the nozzle is a defective nozzle.

  Therefore, according to the present invention, for example, preliminary ejection is performed during image recording without providing a dedicated area for preliminary ejection on the recording medium or the conveyance belt, and each nozzle of the recording head is a normal nozzle or a defective nozzle. It can be determined whether there is. For this reason, it is possible to efficiently detect defective nozzles at high speed while performing image recording.

1 is a block diagram showing an outline of a configuration of a recording system that is a typical embodiment of the present invention. FIG. 2 is an external perspective view illustrating an outline of a configuration of an ink jet recording apparatus included in the recording system illustrated in FIG. 1. FIG. 3 is a perspective view schematically showing a recording paper feed operation of the recording apparatus shown in FIG. 2. 3 is a block diagram illustrating a configuration of a control circuit of the recording apparatus. FIG. 1 is a schematic view of an image forming apparatus showing an embodiment of the present invention. It is a flowchart which shows the procedure of the non-ejection detection process of the paper surface preliminary ejection pattern in the Example of this invention. FIG. 5 is a block diagram illustrating a paper surface preliminary discharge area change control by comparing and determining a print area and a paper preliminary discharge area in an embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings.

  In this specification, “recording” (sometimes referred to as “printing”) is not limited to the case of forming significant information such as characters and graphics, but may be significant. Furthermore, it also represents a case where an image, a pattern, a pattern, or the like is widely formed on a recording medium or a medium is processed regardless of whether or not it is manifested so that a human can perceive it visually.

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Further, “ink” (sometimes referred to as “liquid”) should be interpreted widely as in the definition of “recording (printing)”. Therefore, by being applied on the recording medium, it is used for formation of images, patterns, patterns, etc., processing of the recording medium, or ink processing (for example, solidification or insolubilization of the colorant in the ink applied to the recording medium). It shall represent a liquid that can be made.

  Furthermore, unless otherwise specified, the “recording element” collectively refers to an ejection port or a liquid path communicating with the ejection port and an element that generates energy used for ink ejection.

<Overview of recording system (FIGS. 1 to 4)>
FIG. 1 is a block diagram showing an outline of the configuration of a recording system that is a typical embodiment of the present invention. As shown in FIG. 1, the recording system 300 includes a recording apparatus 301 equipped with an inkjet recording head and a personal computer (PC) 310 connected by a USB cable 340 or the like. The personal computer (PC) 310 is called a host or an information processing apparatus in the following description.

  Connected to the host 310 are a display 320 for displaying various information and an instruction unit 330 including a keyboard and a pointing device for giving instructions to the host. The host 310 includes a CPU 311 for executing various programs and a memory 312 for storing these programs and data. The memory 312 includes a semiconductor memory such as a ROM and a RAM, a hard disk, and the like.

  The ink jet recording apparatus 301 is controlled by the host 310. Accordingly, a printer driver (a kind of control program) for operating the ink jet recording apparatus 301 to perform recording control and an application for generating image data are installed in the host 310. When this printer driver is executed by the CPU 311 during recording, various menu screens related to the recording operation are displayed on the display 320 of the host. As a matter of course, the host generates a print job, generates image data for printing, and supplies the image data to the inkjet recording apparatus 301 as a print job. At this time, the host 310 converts the image data generated using the printer driver into a format that can be interpreted by the inkjet recording apparatus 301, and transmits this to the inkjet recording apparatus 301.

  On the other hand, the inkjet recording apparatus 301 records an image on a recording medium based on image data and a control signal from the host 310.

  In the configuration shown in FIG. 1, the host and the inkjet recording apparatus are connected by a USB cable. However, the connection method is not limited to this. For example, it can be connected by a LAN cable or a wireless interface. Note that the overall configuration of the recording system shown here is merely an example. For example, a plurality of information processing apparatuses 310 and a plurality of recording apparatuses 301 may be provided to form a recording system. Other devices may be connected to the recording system.

  2 is an internal side view showing an outline of the configuration of an ink jet recording apparatus (hereinafter referred to as a recording apparatus) included in the recording system shown in FIG.

  The recording apparatus 301 includes four full-line recording heads (hereinafter referred to as recording heads) 305 that respectively discharge yellow (Y) ink, magenta (M) ink, cyan (C) ink, and black (K) ink. Further, the recording apparatus 301 includes a print buffer memory (hereinafter referred to as VRAM) for temporarily storing image data for each color sent from the host 310, and when the bitmap development of the image data is finished in the VRAM, The recording operation is performed. That is, the roll holder 302 and the conveyance unit 303 are operated to run the recording paper 304 which is a roll-like continuous paper, and according to the contents of the VRAM, YMCK inks are ejected to perform recording.

  Note that the VRAM of the recording apparatus has a capacity for storing image data sufficient to record an image having a predetermined length in the conveyance direction of the recording paper. For example, when the recording width of the recording head 305 is 210 mm, the capacity is a capacity necessary for developing 297 mm (that is, A4 size) of image data into a bitmap in the transport direction. Therefore, it can be said that the VRAM is a page memory or a frame memory.

  The recording apparatus 301 receives various setting data such as a paper type, an ink type, and an image data size from the host 310.

  FIG. 3 is a perspective view schematically showing the recording paper feed operation of the recording apparatus shown in FIG.

  According to FIG. 3, the recording paper 304 is inserted from the roll holder 302 into the transport unit 303, and the recording paper 304 is transported in the direction in which an image is recorded (the arrow direction in FIG. 3) by the transport force of the transport unit 303. This operation is called a feed operation.

  When the development of the image data on the VRAM is completed, the recording head 305 is driven in synchronization with the feed operation, thereby recording on the recording paper 304 based on the image data developed on the VRAM.

  1 to 3, the recording medium is a roll-shaped recording sheet, but a cut sheet may be used as the recording medium. When a roll-shaped recording sheet is used, recording of a predetermined length in the transport direction is set to one page. However, if the sheet is a cut sheet, the literal sheet length can be counted as one page.

  FIG. 4 is a block diagram illustrating a configuration of a control circuit of the recording apparatus.

  4, 400 is an MPU that controls the entire apparatus, 401 is a program ROM that stores various control programs executed by the MPU 401, and 402 is a RAM that is used as a work area when the MPU 401 executes the above-described control program. . Reference numeral 403 denotes a CGROM storing font information for printing, 404 denotes a VRAM 404 used as a print buffer for bit-developing recording data for one page of recording paper, and 405 denotes a communication driver serving as an interface with the host 310. is there. Further, reference numeral 406 denotes a motor driver for controlling roll paper conveyance and movement control of the recording head and the recovery unit, and reference numeral 407 denotes a motor driven by the motor driver 406. Further, reference numeral 408 denotes a head driving circuit that drives the four full-line recording heads 305C, 305M, 305Y, and 305K. The VRAM 404 is configured so that the recording data can be stored in a separate buffer frame for each color component of YMCK.

  Reference numeral 410 denotes a gate array (G / A) having an interface between the VRAM 404 and the CPU 311 and a copy function in the VRAM 404. The gate array (G / A) performs various functions according to instructions from the CPU 311, but can operate independently of the CPU 311.

  Next, an embodiment of the ink ejection failure detection process executed in the recording system having the above configuration will be described.

  FIG. 5 is a sectional side view of the recording apparatus shown in FIGS.

  As shown in FIG. 5, in synchronization with the recording timing, the recording medium 11 is adsorbed to the conveying belt 6 by the negative pressure of a suction fan (not shown) immediately below the conveying belt 6 of the conveying unit 303. Is transported in the sub-scanning direction (arrow direction) by the transport motor 9. This recording timing is generated by detecting the leading end of the recording medium 11 (or the leading end of the recording unit) by the detection sensor 7. The reference pulse signal used for recording by the recording heads 305Y, 305M, 305C, and 305K is based on an encoder signal from a rotary encoder (hereinafter referred to as an encoder) 10 provided around the rotation axis of the driving roller 8. Generated.

  The recording heads 305Y, 305M, 305C, and 305K eject yellow (Y) ink, magenta (M) ink, cyan (C) ink, and black (K) ink, respectively.

  The conveyor belt 6 is wound with a constant tension by a driving roller 8 and a driven roller 5 that are rotated by a conveyor motor 9. The recording heads 305 </ b> Y, 305 </ b> M, 305 </ b> C, and 305 </ b> K record images on the recording medium 11 conveyed by the conveying belt 6 based on the data of each color component (image recording data) transmitted from the host 310. At this time, the image recorded by the CIS sensor 12 is read.

  FIG. 6 is a flowchart illustrating a procedure of ejection failure detection processing.

  First, when recording is started in step S1, in step S2, the recording medium 11 is transported in the sub-scanning direction by the transport belt 6, and at the same time, a timer for measuring the preliminary discharge period is started. Further, in step S3, the process waits until T seconds elapse, and after T seconds elapse, in step S4, nozzles used for preliminary ejection are selected for the nozzles of the recording heads 305Y, 305M, 305C, and 305K.

  Next, in step S5, it is determined whether the selected preliminary ejection nozzle is a nozzle that is also used in printing using image data. If it is determined that the selected nozzle is not a nozzle for recording using image data, the process proceeds to step S7, and preliminary ejection is performed with the selected nozzle. This preliminary ejection is performed on the recording medium 11. On the other hand, if it is determined that the selected nozzle is a nozzle for recording using image data, the process proceeds to step S6, and the preliminary ejection at the selected nozzle is delayed, and then The process proceeds to step S7.

  Next, in step S8, the position where the preliminary discharge measured based on the encoder pulse signal output from the encoder 10 is performed is stored in the memory (RAM 402). In step S9, it is checked whether preliminary ejection has been performed from all the nozzles of the recording head. Here, if it is determined that the preliminary ejection has not been completed from all the nozzles, the process proceeds to step S10, another nozzle is selected as the nozzle for preliminary ejection, and then the process returns to step S5. On the other hand, if it is determined that the preliminary ejection is completed from all the nozzles, the process proceeds to step S11.

  In step S11, the position of the preliminary ejection performed by the recording heads 305Y, 305M, 305C, and 305K is read from the memory, and reflected by the ejected ink on the recording medium at that position by the CIS sensor 12 installed on the downstream side of the conveyance path. Detect the amount. In step S12, it is checked whether or not the sensor detection level (SLVL) as the detection result is “1”. If SLVL = 1, the process proceeds to step S14, and the fact that the inspected nozzle is a normal nozzle is stored in the memory. On the other hand, if SLVL = 0, the process proceeds to step S13, and the fact that the inspected nozzle is a defective ejection nozzle is stored in the memory. After these, the process checks in step S15 whether all nozzles have been inspected. Here, if the inspection is not completed, the process proceeds to step S16 to select another nozzle as the inspection object, and then the process returns to step S12. On the other hand, if it is determined that the inspection is completed, the process is terminated.

  As described above, according to this embodiment, during the recording operation, control is performed so that preliminary ejection is performed from all the nozzles to the recording medium during the actual recording by the image data, and recording is performed by the preliminary ejection. Read recorded dots. Then, from the read result, it is determined which nozzle is a normal nozzle or a defective nozzle, and the result is stored in a memory.

  FIG. 7 is a diagram illustrating the control for changing the preliminary ejection area based on the comparison between the recording area and the preliminary ejection area according to this embodiment.

  As described with reference to FIG. 6, the timer 501 is activated simultaneously with the start of recording, the time is measured, and a trigger signal (TRG) is output from the timer 501 after T seconds have elapsed since the timer activation. At this time, the data load circuit 503 loads each color component data from the register 502 that stores each color component data (preliminary ejection data) used for performing preliminary ejection. On the other hand, another data load circuit 505 loads the image data of each color component used for actual image recording in accordance with the output timing of the encoder signal (ENC) from the encoder 10 from the buffer memory 504.

  The determination circuit 506 inputs these data, and each color component data used for preliminary ejection and each color component data used for image recording have the same value “1” for the same color component, the same recording position (sub-scanning direction), and the same used nozzle. (Ink discharge occurs). In these cases, if the values are the same, the delay circuit 508 delays the output timing of each color component data for preliminary ejection in order to avoid recording due to the overlap of these two data. The delayed color component data is output to OR circuits 509K, 509C, 509M, and 509Y corresponding to the color components. On the other hand, each color component data used for image recording is output from the determination circuit 506 to the OR circuits 509K, 509C, 509M, and 509Y as it is. Accordingly, the OR circuits 509K, 509C, 509M, and 509Y have color component data for preliminary ejection, color component data for delayed preliminary ejection, or color component data for image recording (K-DATA, C-DATA, M-DATA, Y-DATA).

  In this way, the preliminary ejection timing is changed. In this embodiment, preliminary ejection is performed at the next recording timing (next cycle of the encoder signal (ENC)) after the end of ink ejection by each color component data used for image recording. At this time, the position (POS) measured by the discharge position counter 507 is stored in the memory.

  Thereafter, the preliminary ejection positions (POS) of the nozzles of the recording heads 305Y, 305M, 305C, and 305K are loaded from the memory. When the preliminary ejection position reaches the position of the CIS sensor 12 installed on the downstream side of the conveyance path by the conveyance of the recording medium, the optical dots of the dots formed on the recording medium by the ink droplets by the CIS sensor 12 are detected. The amount of reflection is detected.

  Since the relationship between the size of the dots by the ejected ink droplets and the presence or absence of the dots and the amount of optical reflection by the CIS sensor is known, the description thereof is omitted here. In this embodiment, when the ink is normally ejected as a result of the detection, the detection level (SLVL) of the CIS sensor is “1” for the nozzle that ejected the ink. On the other hand, when ink ejection failure occurs, the detection level (SLVL) of the CIS sensor is “0” for the nozzle that performed the ejection operation. In this way, by using the CIS sensor to determine whether or not each nozzle of the recording heads 305Y, 305M, 305C, and 305K has ejected ink, which nozzle is a defective ejection nozzle or a normal nozzle. Is determined.

  Therefore, according to the embodiment described above, the recording head detects the image area and the preliminary ejection area during recording, and if these areas overlap, the preliminary ejection area can be changed to perform preliminary ejection. . In this way, preliminary ejection is performed from all the nozzles, and the result is read by the CIS sensor, whereby it is possible to determine which of all the nozzles are normal nozzles and which are defective nozzles. In this embodiment, the CIS sensor is used as the reading unit. However, the present invention is not limited to this, and a sensor having another photoelectric conversion element such as a CCD sensor may be used.

  Thus, it is not necessary to provide a dedicated area for performing preliminary ejection on the recording medium or the conveyor belt as in the conventional example, and the area for image recording can be used effectively.

  In the embodiment described above, since preliminary ejection is also performed during recording, it is desirable to perform preliminary ejection so as not to affect the image quality as much as possible. For example, pre-discharge is performed in recording with a high recording duty, pre-discharge is performed in a high density area, and pre-discharge is suppressed in a low density area or a medium density area. Minimize impact. Alternatively, it is desirable to perform the preliminary discharge in an area where there is little influence on the recorded image even if the preliminary discharge is performed such as an edge or an edge of the recorded image.

  In the embodiment described above, the recording apparatus using the full line recording head has been described as an example, but the present invention is not limited thereto. For example, the present invention may be applied to a recording apparatus that performs recording by intermittently transporting a recording medium in accordance with reciprocal scanning of the recording head.

Claims (8)

A recording apparatus for recording an image on the recording medium by conveying the recording medium in a predetermined direction and ejecting ink from a plurality of nozzles of the recording head,
A register for storing preliminary ejection data for performing preliminary ejection by the recording head;
A buffer memory for storing image recording data for recording an image by the recording head;
Conveying means for conveying the recording medium;
During recording by the recording head, preliminary ejection data from the register and image recording data from the buffer memory are inputted and compared, and ink from the recording head by the preliminary ejection data and the image recording data is compared. A judging means for judging whether or not the discharges overlap at the same position;
A delay means for delaying the output of the preliminary ejection data when the preliminary ejection data and the ink ejection from the recording head by the image recording data overlap at the same position as determined by the determination means;
Preliminary ejection means for performing preliminary ejection of the recording head based on preliminary ejection data stored in the register or preliminary ejection data delayed by the delay means;
Storage means for storing the position of preliminary ejection performed by the preliminary ejection means;
A reading unit that is provided on the downstream side in the transport direction of the recording medium from the position of the preliminary ejection, and reads the dots formed on the recording medium by the preliminary ejection;
A recording apparatus comprising: a determination unit configured to determine whether the nozzle that has performed the preliminary ejection is a normal nozzle or a defective nozzle according to a result of reading by the reading unit.   The reading unit reads dots formed on the recording medium by the preliminary ejection when the preliminary ejection position of the recording medium reaches the reading position by the reading unit as a result of the conveyance by the conveyance unit. The recording apparatus according to claim 1.   The recording apparatus according to claim 1, wherein the preliminary ejection based on the preliminary ejection data is executed for all of the plurality of nozzles of the recording head.   The recording apparatus according to claim 3, further comprising storage means for storing information on whether all of the plurality of nozzles of the recording head are normal nozzles or defective nozzles.   The recording apparatus according to claim 1, wherein the reading unit includes a photoelectric conversion element.   The recording apparatus according to claim 1, wherein the recording head is a full-line recording head. The full-line recording head includes a recording head that discharges yellow (Y) ink, magenta (M) ink, cyan (C) ink, and black (K) ink, respectively.
The preliminary ejection data is color component data corresponding to yellow (Y) ink, magenta (M) ink, cyan (C) ink, and black (K) ink,
7. The image recording data according to claim 6, wherein the image recording data is color component data corresponding to yellow (Y) ink, magenta (M) ink, cyan (C) ink, and black (K) ink. Recording device. An ejection failure detection method for a recording apparatus for recording an image on the recording medium by transporting the recording medium in a predetermined direction and ejecting ink from a plurality of nozzles of the recording head,
During recording by the recording head, preliminary ejection data and image recording data for recording an image by the recording head are stored from a register for storing preliminary ejection data for performing preliminary ejection by the recording head. A determination step of inputting and comparing the image recording data from the buffer memory and determining whether or not the preliminary ejection data and the ink ejection from the recording head by the image recording data overlap at the same position;
A delay step of delaying the output of the preliminary ejection data when the preliminary ejection data and the ink ejection from the recording head by the image recording data overlap at the same position by the judgment in the judgment step;
A preliminary ejection step in which preliminary ejection is performed from the recording head by the preliminary ejection data stored in the register or the preliminary ejection data delayed in the delay step;
A storage step of storing in a memory the position of the preliminary discharge performed in the preliminary discharge step;
A reading step of reading dots formed on the recording medium by the preliminary discharge by a reading unit provided on the downstream side in the transport direction of the recording medium from the position of the preliminary discharge;
An ejection failure detection method comprising: a discrimination step of discriminating whether the nozzle that has performed the preliminary ejection is a normal nozzle or a defective nozzle according to a result of reading in the reading step.

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