JP2012187821A - Liquid droplet ejecting apparatus and registration gap correcting program of liquid droplet ejecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid droplet ejecting apparatus which can more surely correct a registration gap even when there is an unavoidable abnormal nozzle.SOLUTION: The liquid droplet ejecting apparatus includes a plurality of heads each with nozzle arrays and arranged along a conveyance direction of a recording medium. Test patterns for correcting a gap to a nozzle array direction between heads are each recorded to the recording medium by using each head. The test patterns are detected as the recording medium is conveyed at a detection position of a downstream side. Whether the detection result is abnormal or not is determined. When it is determined to be abnormal, the detection position is changed to a position separated by a preliminarily set distance in the nozzle array direction. When it is determined not to be abnormal, a gap amount to the nozzle array direction between heads is derived on the basis of the detection result. When it is determined to be abnormal, a gap amount to the nozzle array direction between heads is derived on the basis of a detection result detected again after the change, and correction to the gap amount concerned is carried out by using the derived gap amount.

Description

  The present invention relates to a droplet discharge device and a registration error correction program for the droplet discharge device, and in particular, intersects the nozzle row direction with respect to a plurality of recording heads having a nozzle row in which a plurality of nozzles are arranged in a line. The present invention relates to a droplet ejection apparatus that performs recording while conveying a recording medium in a direction, and a registration error correction program for the droplet ejection apparatus.

  Conventionally, in a droplet discharge apparatus that performs recording by arranging recording heads that employ an inkjet recording system in parallel, recording of a plurality of ink colors such as black, yellow, magenta, and cyan is required in order to support full-color recording. A head is used. Further, by ejecting droplets (ink) of the same color (for example, black) from a plurality of recording heads, so-called raster division recording is performed in which a raster constituting an image to be recorded is divided and recorded by the plurality of recording heads. A droplet discharge device is also used in the same manner, and according to such a droplet discharge device, a plurality of lines can be recorded at a time, so that a higher-speed recording process can be performed.

  Conventionally, in such a droplet discharge apparatus provided with a plurality of recording heads, there has been a problem in that a recording position shift, that is, a registration shift, occurs between the recording heads. Therefore, in order to correct this registration deviation, it is common to perform registration adjustment in the nozzle row direction of the printing position for each print head and the direction orthogonal to the nozzle row by forming a registration measurement test pattern. Is.

  As this technique, for example, in a plurality of recording heads having nozzle rows arranged in a line, a predetermined test pattern is recorded by each recording head, and a plurality of recordings are performed by reading the test pattern using an optical sensor. A method for detecting a registration shift between heads has been proposed (see Patent Document 1). As a result, it has become possible to detect a test pattern, which has been performed using a CCD, with an inexpensive optical sensor.

JP 2009-148930 A

  However, in the conventional registration adjustment as described above, information on the amount of registration deviation is obtained based on the presence or absence of dots at positions corresponding to the optical sensor. There may be situations where it is unavoidable that an abnormality occurs in the nozzle, such as a nozzle whose direction is greatly bent, or a nozzle that does not stop discharging. If such an abnormal nozzle happens to be in a position corresponding to the optical sensor, the amount of registration deviation cannot be detected accurately, and the registration deviation may be corrected incorrectly.

  The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a liquid droplet ejection apparatus capable of correcting registration deviation more reliably even when an inevitable abnormal nozzle is present. An object of the present invention is to provide a registration error correction program for a droplet discharge device.

  In order to achieve the above object, the liquid droplet ejection apparatus according to claim 1 has a nozzle row composed of a plurality of nozzles arranged in a nozzle row direction intersecting with the conveyance direction of the recording medium, and the conveyance A plurality of recording heads each arranged along a direction, and a test pattern for correcting a displacement between the plurality of recording heads with respect to the nozzle row direction on each of the recording media using each of the plurality of recording heads. Recording means for recording, detection means for detecting the test pattern according to the conveyance of the recording medium at a predetermined detection position downstream of the plurality of recording heads in the conveyance direction, and a detection result by the detection means A determination unit that determines whether or not there is an abnormality; and when the determination unit determines that there is an abnormality, the detection position of the detection unit is determined in advance in the nozzle row direction. A change unit that changes the position to a position separated by a specified distance, and a shift amount in the nozzle row direction between the plurality of recording heads based on a detection result by the detection unit when the determination unit determines that there is no abnormality. And when the determination means determines that there is an abnormality, the displacement in the nozzle row direction between the plurality of recording heads based on the detection result that is changed by the change means and then detected again by the detection means Deriving means for deriving the amount, and correcting means for correcting the deviation amount using the deviation amount derived by the deriving means.

  According to the droplet discharge device of claim 1, the recording unit has a nozzle row composed of a plurality of nozzles arranged in a nozzle row direction intersecting with the conveyance direction of the recording medium. A test pattern for correcting a shift in the nozzle row direction between the plurality of recording heads arranged along each of the recording heads is recorded on the recording medium using each of the plurality of recording heads.

  In the present invention, the pattern is detected by the detection unit according to the conveyance of the recording medium at a predetermined detection position downstream of the plurality of recording heads in the conveyance direction.

  Here, in the present invention, when the determination unit determines whether or not the detection result by the detection unit is abnormal, and when the change unit determines that the detection unit is abnormal, the detection unit The detection position is changed to a position separated by a predetermined distance in the nozzle row direction.

  In the present invention, when the derivation unit determines that the abnormality is not abnormal by the determination unit, a deviation amount in the nozzle row direction between the plurality of recording heads is derived based on a detection result by the detection unit, When it is determined that the abnormality is detected by the determination unit, a deviation amount with respect to the nozzle row direction between the plurality of recording heads is derived based on a detection result that is changed by the change unit and then detected again by the detection unit. The correction means corrects the deviation amount using the deviation amount derived by the derivation means.

  Thereby, in the droplet discharge device according to the first aspect, the registration deviation can be corrected more reliably.

  According to the present invention, as in the invention described in claim 2, the detection means includes a plurality of sensors fixedly installed at different positions with respect to the nozzle row direction, and the change means is the test. The detection position may be changed by changing a sensor used for pattern detection to one of the plurality of sensors. As a result, the present invention can be realized more easily as compared with the case where the detection unit is moved in the nozzle row direction and the detection position is changed by moving the sensor.

  Further, according to the present invention, as in the invention described in claim 3, the detection means includes a sensor movable in the nozzle row direction, and the change means moves the sensor to change the detection position. It may be changed. As a result, the present invention can be realized at a lower cost compared to a case where the detection means is a plurality of sensors and the sensors are selectively used.

  Further, according to the present invention, as in the invention according to claim 4, the recording unit includes, as the test pattern, for each of the plurality of recording heads, from one end portion of the plurality of nozzles with respect to the nozzle row direction. A linear pattern extending in the nozzle row direction by the plurality of nozzles is recorded on the recording medium by a predetermined number of lines so that the position of the nozzle that does not discharge the droplets toward the other end is shifted by a unit amount. May be. As a result, registration deviation can be corrected more accurately.

  Further, according to the present invention, as in the invention described in claim 5, the recording means performs the recording so that the positions of the nozzles that do not eject the droplets in the nozzle row direction are shifted by one nozzle for each line. May be. As a result, registration deviation can be corrected more accurately.

  On the other hand, in order to achieve the above object, the droplet discharge device according to claim 6 has a nozzle row composed of a plurality of nozzles arranged in a nozzle row direction intersecting with a conveyance direction of the recording medium, A plurality of recording heads each arranged along the transport direction, and a test pattern for correcting a displacement between the plurality of recording heads in the nozzle row direction, using each of the plurality of recording heads. According to the conveyance of the recording medium at a predetermined first position and a second position at which positions in the nozzle row direction at least downstream of the plurality of recording heads in the conveying direction are different from each other. Detecting means for detecting the test pattern, determining means for determining whether the detection result at the first position by the detecting means is abnormal, and the determination When it is determined that there is no abnormality according to the stage, a deviation amount with respect to the nozzle row direction between the plurality of recording heads is derived based on the detection result at the first position by the detection unit, and the determination unit is abnormal. A derivation unit for deriving a deviation amount in the nozzle row direction between the plurality of recording heads based on a detection result at the second position by the detection unit, and a deviation derived by the derivation unit Correction means for correcting the deviation amount using the amount.

  According to the droplet discharge device of the sixth aspect, the recording unit has a nozzle row composed of a plurality of nozzles arranged in a nozzle row direction intersecting the transport direction of the recording medium. A test pattern for correcting a shift in the nozzle row direction between the plurality of recording heads arranged along each of the recording heads is recorded on the recording medium using each of the plurality of recording heads.

  In the present invention, the detection means may detect the recording medium at a predetermined first position and a second position at different positions in the nozzle row direction at least downstream of the plurality of recording heads in the transport direction. The test pattern is detected according to the conveyance, and the determination unit determines whether or not the detection result at the first position by the detection unit is abnormal.

  In the present invention, when the derivation unit determines that there is no abnormality by the determination unit, the displacement of the plurality of recording heads in the nozzle row direction based on the detection result at the first position by the detection unit. When the amount is derived and determined to be abnormal by the determination unit, the shift amount with respect to the nozzle row direction between the plurality of recording heads is derived based on the detection result at the second position by the detection unit. The correction means corrects the deviation amount using the deviation amount derived by the derivation means.

  Thus, in the droplet discharge device according to the sixth aspect, registration deviation can be corrected more reliably.

  On the other hand, in order to achieve the above object, the registration error correction program according to claim 7 has a nozzle row composed of a plurality of nozzles arranged in a nozzle row direction intersecting with the conveyance direction of the recording medium, A registration deviation correction program for a droplet discharge apparatus having a plurality of recording heads each arranged along the transport direction, wherein a test pattern for correcting a deviation in the nozzle row direction between the plurality of recording heads is provided. A recording step of recording on each of the recording media using each of the plurality of recording heads, and the test according to conveyance of the recording medium at a predetermined detection position downstream of the plurality of recording heads in the conveyance direction A detection step of detecting a pattern, a determination step of determining whether or not the detection result of the detection step is abnormal, and the determination step When it is determined that there is an abnormality, when it is determined that the detection position of the detection step is not abnormal in the change step for changing the detection position in the nozzle row direction to a position separated by a predetermined distance, and the determination step A deviation amount with respect to the nozzle row direction between the plurality of recording heads is derived based on the detection result detected in the detection step, and when it is determined that the determination step is abnormal, the change step is performed. A deriving step for deriving a deviation amount in the nozzle row direction between the plurality of recording heads based on the detection result detected again in the detection step after the position is changed, and derived in the deriving step And a correction step for correcting the shift amount using the shift amount.

  Therefore, according to the registration deviation correction program according to the seventh aspect, the computer can be operated in the same manner as the invention according to the first aspect. It is possible to correct the deviation of the rotation.

  According to the present invention, even if there is an inevitable abnormal nozzle, it is possible to more reliably correct registration deviation.

1 is a cross-sectional side view illustrating a configuration of an image forming apparatus according to an embodiment. 1 is a block diagram illustrating a system configuration of an image forming apparatus according to an embodiment. FIG. 3 is a schematic top view for explaining an installation state of the optical sensor of the image forming apparatus according to the embodiment. (A) is a schematic perspective view of the head module of the image forming apparatus according to the embodiment, and (B) and (C) are schematic bottom views showing the arrangement of nozzles in the head module. FIG. 6 is a plan view illustrating an example of a test pattern used by the image forming apparatus according to the embodiment when correcting registration displacement. (A) and (B) are schematic views for explaining a registration correction process executed in the image forming apparatus according to the embodiment. It is a data block diagram which shows the reference data which concern on embodiment. It is a flowchart which shows the flow of a process of the 1st registration deviation correction process program which concerns on 1st Embodiment. It is a flowchart which shows the flow of a process of the 2nd registration error correction process program which concerns on 2nd Embodiment. FIG. 10 is a schematic top view for explaining another example of the installation state of the optical sensor of the image forming apparatus according to the embodiment. (A) thru | or (C) is a figure which shows the modification of a test pattern. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, a description will be given of an example in which the present invention is applied to an image forming apparatus that forms a monochrome image by a plurality of recording heads.

[First Embodiment]

  FIG. 1 is a cross-sectional side view showing the configuration of the image forming apparatus 1 according to the first embodiment. As shown in FIG. 1, the image forming apparatus 1 according to the first embodiment has an upstream side with respect to the conveyance direction Y of a recording medium K such as a sheet (hereinafter, “with respect to the conveyance direction Y of the recording medium K”). The sheet feeding / conveying section 10 for feeding and conveying the recording medium K is provided. On the downstream side of the paper feeding / conveying unit 10, a processing liquid applying unit 11 that applies a processing liquid to an image forming surface (image forming surface) of the recording medium K along the conveying direction Y, and an image of the recording medium K An image forming unit 12 for forming an image on the forming surface, an ink drying unit 13 for drying the image formed on the image forming surface, an image fixing unit 14 for fixing the dried image on the recording medium K, and a recording medium on which the image is fixed A discharge unit 15 for discharging K is provided.

  The paper feeding / conveying unit 10 is provided with a stacking unit 16 on which recording media K are stacked, and the recording media K stacked on the stacking unit 16 are fed one by one downstream of the stacking unit 16. A paper feed unit 17 is provided. The recording medium K fed by the paper feeding unit 17 is conveyed to the processing liquid coating unit 11 via a conveying unit 19 configured by a pair of rollers 18.

  In the treatment liquid application unit 11, a treatment liquid application drum 20 is rotatably disposed. The processing liquid coating drum 20 is provided with a holding member 21 that holds the recording medium K by sandwiching the leading end of the recording medium K, and the recording liquid is recorded on the surface of the processing liquid coating drum 20 via the holding member 21. With the medium K held, the recording medium K is conveyed downstream by the rotation of the treatment liquid coating drum 20.

  Note that an intermediate conveying drum 22, an image forming drum 23, an ink drying drum 24, and a fixing drum 25, which will be described later, are also provided with a holding member 21 as in the case of the treatment liquid coating drum 20. The holding member 21 transfers the recording medium K from the upstream drum to the downstream drum.

  A processing liquid coating device 26 and a processing liquid drying device 27 are disposed above the processing liquid coating drum 20 along the circumferential direction of the processing liquid coating drum 20. The processing liquid is applied to the image forming surface, and the processing liquid is dried by the processing liquid drying device 27.

  Here, the treatment liquid reacts with the ink to aggregate the color material (pigment) and has an effect of promoting separation of the color material (pigment) and the solvent. The treatment liquid application device 26 is provided with a storage portion 28 for storing the treatment liquid, and a part of the gravure roller 29 is immersed in the treatment liquid.

  A rubber roller 30 is disposed in pressure contact with the gravure roller 29, and the rubber roller 30 contacts the image forming surface (front surface) side of the recording medium K to apply the processing liquid. Further, a squeegee (not shown) is in contact with the gravure roller 29 to control the amount of processing liquid applied to the image forming surface of the recording medium K.

  Ideally, the treatment liquid film thickness is sufficiently smaller than the ink droplets of the head droplets. For example, in the case of a droplet ejection amount of 2 pl, the average diameter of the ink droplets of the head droplet is 15.6 μm, and when the treatment liquid film thickness is large, the ink dots are processed without contacting the image forming surface of the recording medium K. Float in liquid. In order to obtain a landing dot diameter of 30 μm or more with a droplet ejection amount of 2 pl, it is preferable to set the treatment liquid film thickness to 3 μm or less.

  On the other hand, in the treatment liquid drying device 27, a hot air nozzle 31 and an infrared heater 32 (hereinafter referred to as “IR heater 32”) are disposed close to the surface of the treatment liquid application drum 20. A solvent such as water in the processing liquid is evaporated by the hot air nozzle 31 and the IR heater 32 to form a solid or thin film processing liquid layer on the image-formed surface side of the recording medium K. By thinning the treatment liquid in the treatment liquid drying step, the dots formed by ink droplets in the image forming unit 12 come into contact with the surface of the recording medium K to obtain a necessary dot diameter, and the thinned treatment liquid It is easy to obtain an effect of reacting and aggregating the coloring material and fixing it on the surface of the recording medium K.

  In this way, the recording medium K on which the processing liquid is applied and dried on the image forming surface by the processing liquid application unit 11 is transferred to the intermediate transport unit 33 provided between the processing liquid application unit 11 and the image forming unit 12. Be transported.

  The intermediate conveyance unit 33 is rotatably provided with an intermediate conveyance drum 22, and holds the recording medium K on the surface of the intermediate conveyance drum 22 via a holding member 21 provided on the intermediate conveyance drum 22. The recording medium K is conveyed downstream by the rotation of the conveying drum 22.

  An image forming drum 23 is rotatably provided in the image forming unit 12, and the recording medium K is in close contact with the surface of the image forming drum 23 via a holding member 21 provided on the image forming drum 23. The recording medium K is conveyed downstream by the rotation of the image forming drum 23.

  An ink jet line head 34 (hereinafter referred to as “recording head 34”) in which a plurality of nozzles each ejecting ink droplets are provided in a one-dimensional manner near the surface of the image forming drum 23 at the top of the image forming drum 23. ) Is provided. In the head unit 35, recording heads 34 each ejecting K (black) ink droplets are arranged above the image forming drum 23 along the circumferential direction of the image forming drum 23. Each black image is formed on the processing liquid layer formed on the image forming surface.

  The treatment liquid has an effect of aggregating the color material (pigment) and latex particles dispersed in the ink into the treatment liquid, and forms an aggregate on the recording medium K where no color material flows. As an example of the reaction between the ink and the treatment liquid, using a mechanism in which acid is contained in the treatment liquid and the pigment dispersion is destroyed and aggregated by the PH down, color material bleeds and droplet ejection interference due to liquid coalescence when the ink hits the enemy To avoid.

  The recording head 34 ejects droplets in synchronization with an encoder (not shown) that detects the rotational speed disposed on the image forming drum 23, thereby determining the landing position with high accuracy and at the same time. It is possible to reduce droplet ejection spots without depending on the shake, the accuracy of the rotary shaft 36, and the drum surface speed.

  The head unit 35 can be retracted from the upper part of the image forming drum 23, and maintenance operations such as cleaning the nozzle surface of the recording head 34 and discharging the thickened ink are performed by moving the head unit 34 from the upper part of the image forming drum 23. Implemented by evacuation.

  The recording medium K on which an image is formed on the image forming surface is transported to an intermediate transport unit 37 provided between the image forming unit 12 and the ink drying unit 13 by the rotation of the image forming drum 23. Since the configuration of the unit 37 is substantially the same as that of the intermediate conveyance unit 33, description thereof is omitted.

  An ink drying drum 24 is rotatably provided in the ink drying unit 13, and a plurality of hot air nozzles 38 and IR heaters 39 are arranged above the ink drying drum 24 in the vicinity of the surface of the ink drying drum 24. It is installed. With the hot air from the hot air nozzle 38 and the IR heater 39, the solvent separated by the color material aggregating action is dried in the image forming portion of the recording medium K, and a thin image layer is formed.

  The temperature of the warm air varies depending on the conveyance speed of the recording medium K, but is usually set to 50 to 70 ° C. The evaporated solvent is discharged together with air to the outside of the image forming apparatus 1, but the air is collected. This air may be cooled by a cooler / radiator or the like and recovered as a liquid.

  The recording medium K on which the image on the image forming surface is dried is conveyed to the intermediate conveyance unit 40 provided between the ink drying unit 13 and the image fixing unit 14 by the rotation of the ink drying drum 24. About 40, since the structure is substantially the same as the intermediate conveyance part 33, description is abbreviate | omitted.

  An image fixing drum 25 is rotatably provided in the image fixing unit 14. In the image fixing unit 14, latex particles in the thin image layer formed on the ink drying drum 24 are heated / pressurized. It has a function of melting and fixing on the recording medium K.

  A heating roller 41 is disposed above the image fixing drum 25 in the vicinity of the surface of the image fixing drum 25. The heating roller 41 has a halogen lamp incorporated in a metal pipe made of aluminum or the like having a high thermal conductivity, and the heating roller 41 applies thermal energy equal to or higher than the Tg temperature of the latex. As a result, the latex particles are melted and pressed into the irregularities on the recording medium K for fixing, and the irregularities on the image surface are leveled to obtain glossiness.

  A fixing roller 42 is provided on the downstream side of the heating roller 41. The fixing roller 42 is disposed in pressure contact with the surface of the image fixing drum 25 and is configured to obtain a nip force with the image fixing drum 25. For this reason, at least one of the fixing roller 42 and the image fixing drum 25 has an elastic layer on the surface and has a uniform nip width with respect to the recording medium K.

  The recording medium K on which the image on the image forming surface is fixed by the above-described steps is conveyed to the discharge unit 15 provided on the downstream side of the image fixing unit 14 by the rotation of the image fixing drum 25.

  FIG. 2 is a block diagram illustrating a system configuration of the image forming apparatus 1. As shown in FIG. 2, the image forming apparatus 1 includes a fan / motor driver 50, a communication interface 51, a system controller 52, an image memory 53, a ROM 54, a motor driver 55, a heater driver 56, a print control unit 57, and an image buffer memory 58. , An image processing device 59, a head driver 60, and the like.

  The communication interface 51 performs communication processing with the host device 99 that is used by the user to instruct the image forming apparatus 1 to form an image. As the communication interface 51, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted.

  Image information sent from the host device 99 is taken into the image forming apparatus 1 via the communication interface 51 and temporarily stored in the image memory 53. The image memory 53 is a storage device that stores image information input via the communication interface 51, and information is read and written through the system controller 52. The image memory 53 is not limited to a memory made of a semiconductor element, and a magnetic storage medium such as a hard disk may be used.

  The system controller 52 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire image forming apparatus 1 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. That is, the system controller 52 controls each unit such as the fan / motor driver 50, the communication interface 51, the image memory 53, the ROM 54, the motor driver 55, and the heater driver 56, and performs communication control with the host device 99 and the image memory 53. In addition, the read / write control of the ROM 54 is performed, and a control signal for controlling the motor 61, the IR heaters 32, 39, and the like of the recording medium conveyance system is generated. In addition to the control signal, image information stored in the image memory 53 is transmitted to the print control unit 57.

  The ROM 54 stores programs executed by the CPU of the system controller 52 and various data necessary for control. The ROM 54 may be a non-rewritable storage means, but when various data are updated as necessary, it is preferable to use a rewritable storage means such as an EEPROM.

  The image memory 53 is used as a temporary storage area for image information, and is also used as a program development area and a calculation work area for the CPU.

  The motor driver 55 is a driver (drive circuit) that drives the motor 61 of the recording medium conveyance system in accordance with an instruction from the system controller 52. The heater driver 56 is a driver that drives the IR heaters 32 and 39 in accordance with instructions from the system controller 52.

  The fan / heater driver 50 is a driver that drives each fan / motor connection circuit 38 </ b> A according to an instruction from the system controller 52.

  On the other hand, the print control unit 57 includes a CPU and its peripheral circuits, and generates an ejection control signal from image information in the image memory 53 in cooperation with the image processing unit 59 in accordance with the control of the system controller 52. In addition to performing various processes and corrections for the purpose, the generated ejection data is supplied to the head driver 60 to control ejection driving of the head unit 35.

  Connected to the print controller 57 is a ROM 62 that stores programs executed by the CPU of the print controller 57 and various data necessary for control. The ROM 62 may also be a rewritable storage means. However, when various data are updated as necessary, it is preferable to use a rewritable storage means such as an EEPROM.

  The image processing unit 59 generates dot arrangement data from the input image information, and performs a half training process (intermediate gradation process) on the input image information to determine a high-quality dot position.

  In FIG. 2, the image processing unit 59 is illustrated as being separate from the system controller 52 and the print control unit 57, but for example, the image processing unit 59 is included in the system controller 52 or the print control unit 57. A part thereof may be configured.

  In addition, the print control unit 57 includes a discharge data generation function that generates ink discharge data (control signals for the actuator corresponding to the nozzles of the recording head 34) based on the dot arrangement data generated by the image processing unit 59, and a drive. And a waveform generation function. Accordingly, the print control unit 57 is a unit that generates a waveform signal indicating a drive waveform used when ink droplets are ejected from the recording head 34. In the generation of the waveform signal, when an externally generated waveform signal is input to the image forming apparatus 1, the externally generated waveform signal may be stored or retained and used. .

  The ejection data generated by the ejection data generation function is given to the head driver 60, and the ink ejection operation of the head unit 35 is controlled.

  The drive waveform generation function is a function of generating a drive signal waveform for driving an actuator corresponding to each nozzle of the recording head 34, and the signal (drive waveform) generated by the drive waveform generation function is a head driver. 60. The signal generated by the drive waveform generation function may be digital waveform data or an analog voltage signal. The head driver 60 is means for sending out the generated waveform signal to the recording head 34 to eject ink droplets.

  Incidentally, in the image forming apparatus 1, the four recording heads 34 provided in the head unit 35 can be individually moved in a direction perpendicular to the transport direction Y (hereinafter referred to as “nozzle row direction”). Ball screws 64 are provided corresponding to the recording heads 34.

  Each ball screw 64 is connected to a print control unit 57 via a motor 65 that rotates a screw portion of the ball screw 64 and a motor driver 63 that rotates a rotation shaft of the motor 65. The position of the recording head 34 in the nozzle row direction can be individually adjusted.

  On the other hand, an image buffer memory 58 is connected to the print control unit 57, and image information, parameters, and other data are temporarily stored in the image buffer memory 58 during image information processing in the print control unit 57. In FIG. 2, the image buffer memory 58 is shown in a form associated with the print control unit 57, but it can also be used as the image memory 53.

  Further, two optical sensors 67A and 67B are connected to the print control unit 57 via an A / D converter 66, and detection signals from the respective optical sensors 67A and 67B are transmitted to the print control unit 57 as digital data ( Hereinafter, it is converted into “detection data”) and input.

  The optical sensors 67A and 67B are provided for detecting a test pattern 80 (also see FIG. 5), which will be described later, for measuring the registration deviation amount. The optical sensors 67A and 67B are predetermined on the downstream side of each recording head 34. It is provided at the position.

  In the image forming apparatus 1 according to the present embodiment, as shown in FIG. 3, the optical sensors 67A and 67B are provided on the upper part of the image forming drum 23 and on the downstream side of the recording heads 34. The position is not limited to this, and may be provided at any position as long as the test pattern 80 can be detected on the downstream side of each recording head 34 such as the upper portion of the intermediate conveyance drum 22 provided in the intermediate conveyance unit 37. Good. In the image forming apparatus 1, the reflective optical sensors are applied as the optical sensors 67 </ b> A and 67 </ b> B. However, the present invention is not limited thereto, and other sensors such as a transmissive optical sensor may be applied.

  The print control unit 57 and the system controller 52 can be integrated to form a single processor.

  The image forming apparatus 1 and the host apparatus 99 are connected by a printer cable, and various data processed by the host apparatus 99 are recorded by the image forming apparatus 1, and printer status such as error information of the image forming apparatus 1 is recorded. Can be detected by the host device 99.

  4A is a schematic perspective view showing the appearance of the recording head 34, and FIG. 4B is a schematic bottom view showing the arrangement of nozzles in the recording head 34. As shown in FIG. As shown in FIG. 4A, the recording head 34 according to this embodiment includes a long head module 70 supported by a long support unit 70A. Further, as shown in FIG. 4B, in the recording head 34 according to the present embodiment, the nozzle rows that intersect with the transport direction Y (orthogonal in the present embodiment) on the ink ejection surface 70B of the head module 70. A plurality of nozzles 71 are arranged in a line in the direction X.

  The arrangement of the plurality of nozzles 71 is not limited to a line, and as an example, as shown in FIG. 4C, a position shifted in the nozzle row direction X so as not to overlap the transport direction Y of the recording medium K. It may be arranged two-dimensionally. In this case, by controlling the droplet discharge timing of each nozzle 71 based on the position of each nozzle 71 in the transport direction Y, recording on the recording medium K can be performed.

  Incidentally, the image forming apparatus 1 according to the present embodiment is provided with a registration deviation (hereinafter referred to as “registration deviation”) correction function that corrects deviations between the recording heads 34 with respect to the nozzle row direction X. Yes.

  In the registration deviation correction function according to the present embodiment, the deviation between the recording heads 34 in units of the distance between adjacent dots recorded on the recording medium K by the nozzle 71 of the recording head 34 (hereinafter, “first registration deviation”). In addition, the displacement between the recording heads 34 that is shorter than the distance between the dots (hereinafter referred to as “second registration displacement”) is also corrected. Here, the registration error correction function according to the present embodiment will be described in detail. In the image forming apparatus 1 according to the present embodiment, the registration error correction function can be executed by using either the optical sensor 67A or the optical sensor 67B. However, in order to avoid complications, the optical sensor is used here. A case where 67A is used will be described.

  FIG. 5 is a diagram illustrating an example of a test pattern used when the registration error correction function is executed in the image forming apparatus 1 according to the present embodiment. As shown in the figure, the test pattern 80 used in this embodiment is a nozzle that does not eject ink droplets from one end to the other end in the nozzle row direction X of the plurality of nozzles 71 for each of the recording heads 34. A linear pattern (hereinafter also referred to as “line”) extending in the nozzle row direction X by each nozzle 71 in advance so that the position of 71 is shifted by a unit amount (one dot in the present embodiment). A predetermined number of lines are recorded on the recording medium K.

  In the registration error correction function according to the present embodiment, the test pattern 80 is used to derive the shift amount of the first registration error and the shift amount of the second registration error.

  Specifically, the test pattern 80 is recorded on the recording medium K for each of the recording heads 34, while the ink droplets are ejected from the line first recorded on the recording medium K in the test pattern 80 for each recording head 34. The difference between the recording heads 34 in the number of lines up to the line in which the unoccupied area is detected based on the detection signal of the optical sensor 67A is derived as the shift amount of the first registration shift. Note that, in the image forming apparatus 1 according to the present embodiment, the predetermined recording head 34 (the recording head 34 positioned on the most upstream side in the present embodiment) is used as a reference as the shift amount of the first registration shift. Then, a relative shift amount with respect to the nozzle row direction X of the other recording head 34 with respect to the recording head 34 is derived.

  On the other hand, in the image forming apparatus 1 according to the present embodiment, the amount of deviation with respect to the nozzle row direction X between the nozzle 71 provided in the recording head 34 and the detection position by the optical sensor 67A is set in advance shorter than the inter-dot distance. A plurality of reference data indicating detection signals by the optical sensor 67A corresponding to a predetermined region including a region where ink droplets are not ejected when the test patterns 80 are recorded with a plurality of distances being different from each other are associated. It is stored in advance in the ROM 54 in association with the deviation amount.

  In the image forming apparatus 1 according to the present embodiment, the detection signal obtained by detecting the test pattern 80 by the optical sensor 67A among the plurality of detection signals indicated by the reference data for each of the recording heads 34. The deviation amount associated with the detection signal closest to is derived as the deviation amount of the second registration deviation relating to the recording head.

  For example, when the recording state of a plurality of lines in the transport direction Y is the state shown in FIG. 6A, and the detection position by the optical sensor 67A is a in FIG. 6A, the detection signal by the optical sensor 67A. As shown in FIG. 6B as an example. On the other hand, when the detection position by the optical sensor 67A is b in FIG. 6A, the detection signal by the optical sensor 67A is as shown in FIG. 6B as an example, and further, the optical sensor 67A. When the detection position by is c in FIG. 6A, the detection signal by the optical sensor 67A is as shown in c of FIG. 6B as an example.

  Therefore, the reference data is stored in advance as described above, and the detection obtained by detecting the test pattern 80 by the optical sensor 67A among the plurality of detection signals indicated by the reference data for each of the recording heads 34. By specifying the shift amount associated with the detection signal closest (similar) to the signal, the shift amount of the second registration shift can be derived.

  FIG. 7 schematically shows reference data applied in the image forming apparatus 1 according to the present embodiment.

  As shown in the figure, the reference data according to the present embodiment is predetermined for each of a plurality of adjacent lines (5 lines in the present embodiment) in the test pattern 80 and shorter than the inter-dot distance described above. In this embodiment, the distance is changed by a plurality of distances (in this embodiment, a state in which the distance between dots is moved by one-fourth of the inter-dot distance in one direction in the nozzle array direction X, a state in which the nozzle array direction X is not moved at all, The detection data detected by the optical sensor 67A is stored and configured for each of the three states (moved in the other direction by a quarter of the inter-dot distance).

  Next, as an operation of the image forming apparatus 1 according to the present embodiment, an operation of the image forming apparatus 1 when executing a registration error correction function particularly related to the present invention will be described with reference to FIG. 8 is executed by a CPU provided in the system controller 52 of the image forming apparatus 1 at a predetermined timing (in this embodiment, a timing when a power switch (not shown) of the image forming apparatus 1 is turned on). 6 is a flowchart showing a flow of processing of the first registration deviation correction processing program, which is stored in the ROM 54 in advance.

  In step 101 of FIG. 9, the print control unit 57 is controlled so as to start recording of the test pattern 80 on the recording medium K by any one of the recording heads 34 (hereinafter referred to as “processing target recording head”). In response to this, the print control unit 57 starts recording the test pattern 80 by the processing target recording head.

  In the next step 103, the timing to start storing the detection data obtained via the optical sensor 67A and the A / D converter 66 is reached by waiting until the detection of the test pattern 80 by the optical sensor 67A is started. Wait until

  In the image forming apparatus 1 according to the present embodiment, the optical sensor 67A detects a region other than the region corresponding to the position of the nozzle that does not eject ink droplets in the linear pattern recorded at the beginning of the test pattern 80. Positioning is performed so as to be a target, and the processing of step 103 is performed by the above-described detection data obtained via the print control unit 57, and the optical sensor 67A has dots formed by ink droplets in a region to be detected. This is performed by determining that the detection of the test pattern 80 by the optical sensor 67A is started when the threshold value is equal to or lower than a predetermined first threshold value. Arrangement position of optical sensor 67A from recording head to be processed when recording test pattern 80 after recording is started Other also may of course in the form of such to wait until the movement time of the recording medium K has passed in.

  In the next step 105, the detection data is stored in the image memory 53, and in the next step 107, the detection data is waited until the detection of the test pattern 80 by the optical sensor 67A is completed. Wait until the timing to end the storage arrives.

  Note that in the image forming apparatus 1 according to the present embodiment, the processing of step 107 is determined in advance so that the detection data indicates that the dot is not formed in the region to be detected by the optical sensor 67A. This is performed by determining that the detection of the test pattern 80 by the optical sensor 67A has been completed when a plurality of lines (in this embodiment, three lines in this embodiment) that are equal to or greater than the second threshold value continue. However, the present invention is not limited to this, and after the detection of the test pattern 80 by the optical sensor 67A is started, it waits until the moving time of the recording medium K corresponding to the length of the test pattern 80 in the recording medium K conveyance direction Y elapses. Needless to say, other forms may be used.

  Further, the system controller 52 stores the detection data repeatedly executed by the process of step 105, and starts the test pattern 80 on the recording medium K starting from the timing when the detection of the test pattern 80 is started by the process of step 103. This is performed for each line of the test pattern 80 by storing the detection data at a sampling period synchronized with the recording timing.

  In the next step 109, the storage of the detection data started by the process of step 105 is ended, and in the next step 111, the above-described processes of steps 101 to 109, that is, the test pattern 80 by the processing target recording head is performed. It is determined whether recording, detection of the test pattern 80 by the optical sensor 67A, and storage of the detected data have been completed for all the recording heads 34. If a negative determination is made, the process returns to step 101, while an affirmative determination is made. At that point, the process proceeds to step 113. When repeatedly executing the processing from step 101 to step 109, the recording head 34 that has not been set as the processing target recording head until then is set as the processing target recording head.

  In step 113, the detection data for each recording head 34 stored in the image memory 53 by the above processing is read from the image memory 53, and in the next step 115, the above-described reference data is read from the ROM 54.

  In the next step 117, it is determined whether or not the displacement amounts of the first registration error and the second registration error can be derived based on the detection data and the reference data obtained by the above processing, and a negative determination is made. When it becomes, it transfers to step 119. Note that in the image forming apparatus 1 according to the present embodiment, the determination in this step 117 is performed by detecting the region corresponding to the position of the nozzle that does not eject ink droplets in the detection data corresponding to the detection region of the test pattern 80. However, the present invention is not limited to this, but the degree of similarity between the detected data and the reference data is determined. Alternatively, another determination may be made such as determining whether there is a recording head 34 that does not have a predetermined degree or more.

  In step 119, it is determined whether or not the number of executions of the process in step 117 after the execution of the first registration deviation correction processing program is started. If the determination is affirmative, the process proceeds to step 121. Then, the optical sensor to be used is set to be changed to the optical sensor 67B. In the next step 123, the detection data stored by the above processing is erased from the image memory 56, and then the process returns to step 101.

  On the other hand, if a negative determination is made in step 119, it is assumed that the number of executions of the process in step 117 after the execution of the first registration deviation correction processing program is started is second, and the process proceeds to step 125. The first registration error correction processing program is terminated after a predetermined warning process is executed to warn that the registration error correction function could not be implemented. In the image forming apparatus 1 according to the present embodiment, as the warning process, a process of transmitting information indicating that the registration misalignment correction function could not be performed to the host apparatus 99 is applied. However, the present invention is not limited to this, a sounding device such as a buzzer is provided in the image forming apparatus 1, a process for causing the sounding apparatus to sound, a display device is provided in the image forming apparatus 1, and a warning message or warning is given to the display device. Various processes such as a process of displaying a mark indicating the above may be applied alone or in combination.

  On the other hand, if the determination in step 117 is affirmative, the process proceeds to step 127, and the recording head 34 excluding the recording head 34 used as a reference when deriving the shift amount of the first registration according to the above-described processing. Then, in the next step 129, the shift amount of the second registration shift is derived for each of the recording heads 34 in accordance with the above-described processing.

  In the next step 130, the ball screw 64 is controlled so as to adjust the position of each recording head 34 so that the deviation amount derived by the process of step 129 is eliminated, and then the deviation amount derived by the process of step 127 is eliminated. Thus, after controlling the ball screw 64 so as to adjust the position of the recording head 34 excluding the recording head 34 used as a reference when deriving the deviation amount, the first registration deviation correction processing program is terminated.

[Second Embodiment]

  Hereinafter, a second embodiment of the present invention will be described. The configuration of the image forming apparatus 1 according to the second embodiment is the same as that of the image forming apparatus 1 according to the first embodiment, and a description thereof will be omitted here.

  Hereinafter, as an operation of the image forming apparatus 1 according to the second embodiment, an operation of the image forming apparatus 1 when executing a registration error correction function particularly related to the present invention will be described with reference to FIG. 9 is executed by a CPU provided in the system controller 52 of the image forming apparatus 1 at a predetermined timing (in this embodiment, a timing when a power switch (not shown) of the image forming apparatus 1 is turned on). 6 is a flowchart showing a flow of processing of the second registration deviation correction processing program, which is stored in the ROM 54 in advance.

  In step 201 in the figure, the print controller 57 is controlled to start recording of the test pattern 80 on the recording medium K by any one recording head 34 (processing target recording head). In response to this, the print control unit 57 starts recording the test pattern 80 by the processing target recording head.

  In the next step 203, the timing to start storing the detection data obtained via the optical sensor 67A and the A / D converter 66 by waiting until the detection of the test pattern 80 by the optical sensors 67A and 67B is started. Wait until it arrives.

  Note that also in the image forming apparatus 1 according to the present embodiment, the optical sensor 67A has a detection target in a region other than the region corresponding to the position of the nozzle that does not eject ink droplets in the first recorded line of the test pattern 80. The processing in step 203 indicates that the detection data obtained via the print control unit 57 indicates that dots by ink droplets are formed in a region to be detected by the optical sensor 67A. However, the present invention is not limited to this, and the recording of the test pattern 80 is started when it is determined that the detection of the test pattern 80 by the optical sensor 67A has started. After that, the recording from the processing target recording head when recording the test pattern 80 to the position where the optical sensor 67A is arranged is recorded. Until after the moving time of the medium K other also may of course in the form of such to wait.

  In the next step 205, storage of the detection data obtained by both the optical sensor 67A and the optical sensor 67B into the image memory 53 is started. In the next step 207, the test pattern 80 is detected by the optical sensor 67A. By waiting until the process is completed, the process waits until the timing for ending the storage of the detection data comes.

  Note that also in the image forming apparatus 1 according to the present embodiment, the process of step 207 is determined in advance so that the detection data indicates that the dot is not formed in a region to be detected by the optical sensor 67A. This is performed by determining that the detection of the test pattern 80 by the optical sensor 67A has been completed when a plurality of lines (in this embodiment, three lines in this embodiment) that are equal to or greater than the second threshold value continue. However, the present invention is not limited to this, and waiting until the moving time of the recording medium K corresponding to the length of the test pattern 80 in the transport direction Y elapses after the detection of the test pattern 80 by the optical sensor 67A is started. Needless to say, other forms may be used.

  Further, the system controller 52 stores the detection data repeatedly executed by the process of step 205, and starts the test pattern 80 on the recording medium K with the timing at which the detection of the test pattern 80 is started by the process of step 203 as a starting point. This is performed for each line of the test pattern 80 by storing the detection data at a sampling period synchronized with the recording timing.

  In the next step 209, the storage of the detection data started by the process of step 205 is ended, and in the next step 211, the above-described processes of steps 201 to 209, that is, the test pattern 80 by the processing target recording head is performed. It is determined whether recording, detection of the test pattern 80 by the optical sensor 67A and the optical sensor 67B, and storage of each detection data have been completed for all the recording heads 34. If the determination is negative, the process returns to step 201. On the other hand, when an affirmative determination is made, the process proceeds to step 213. When repeatedly executing the processing from step 201 to step 209, the recording head 34 that has not been set as the processing target recording head until then is set as the processing target recording head.

  In step 213, the detection data for each of the recording heads 34 and each of the optical sensors 67A and 67B stored in the image memory 53 by the above processing is read from the image memory 53, and in the next step 215, the ROM 54 is read. Read the reference data described above.

  In the next step 217, it is determined whether or not the deviation amounts of the first registration deviation and the second registration deviation can be derived based on the detection data and the reference data by the optical sensor 67A obtained by the above processing. If the determination is affirmative, the process proceeds to step 219.

  In step 219, for the data detected by the optical sensor 67A, the shift amount of the first registration shift is derived for each of the print heads 34 except the print head 34 used as a reference when deriving the shift amount according to the above-described processing. Then, in the next step 221, the shift amount of the second registration shift is derived for each of the recording heads 34 in accordance with the above-described processing for the detected data, and then the process proceeds to step 229.

  On the other hand, if a negative determination is made in step 217, the process proceeds to step 223, where each of the first registration deviation and the second registration deviation is based on the detection data and reference data obtained by the optical sensor 67B obtained by the above processing. It is determined whether or not the deviation amount can be derived. If the determination is affirmative, the process proceeds to step 225.

  In step 225, for the detection data from the optical sensor 67B, the shift amount of the first registration shift is derived for each of the print heads 34 except the print head 34 used as a reference when deriving the shift amount according to the above-described processing. Then, in the next step 227, the shift amount of the second registration shift is derived for each of the recording heads 34 in accordance with the above-described processing for the detected data, and then the process proceeds to step 229.

  Note that in the image forming apparatus 1 according to the present embodiment, the determination in Steps 217 and 223 is performed using the detection data corresponding to the detection region of the test pattern 80 as the region corresponding to the position of the nozzle that does not eject ink droplets. This is performed by determining whether there is a recording head 34 that does not have a predetermined third threshold value or higher as a detection target. However, the present invention is not limited to this. Other determinations may be made, such as determining whether there is a recording head 34 that does not have a degree of similarity equal to or greater than a predetermined level.

  In step 229, the ball screw 64 is controlled so as to adjust the position of each recording head 34 so that the deviation amount derived by the processing in step 221 or step 227 is eliminated, and then the processing in step 219 or step 225 is performed. After the ball screw 64 is controlled so as to adjust the position of the recording head 34 excluding the recording head 34 used as a reference when deriving the deviation amount, the second registration deviation correction processing program is eliminated. Exit.

  On the other hand, if a negative determination is made in step 223, the process proceeds to step 231, and after executing a warning process that is predetermined to warn that the registration error correction function could not be performed, The two-registration misalignment correction processing program is terminated. In the image forming apparatus 1 according to the present embodiment, as the warning process, a process of transmitting information indicating that the registration error correction function could not be performed to the host apparatus 99 is applied. However, the present invention is not limited to this, a sounding device such as a buzzer is provided in the image forming apparatus 1, a process for causing the sounding apparatus to sound, a display device is provided in the image forming apparatus 1, and a warning message or warning is given to the display device. Various processes such as a process of displaying a mark indicating the above may be applied alone or in combination.

  In each of the above-described embodiments, the case where the two optical sensors 67A and 67B are used has been described. However, the present invention is not limited to this, and three or more optical sensors may be used. In this case, each optical sensor is arranged so that each detection target position is different. In this case, as compared with each of the embodiments, the registration deviation can be corrected more reliably by the registration deviation correction process.

  In each of the above embodiments, the case where the position of each recording head 34 in the nozzle row direction X is moved by the ball screw 64 has been described. However, the present invention is not limited to this. Other position moving means such as solenoids and piezoelectric elements may be applied.

  In each of the above-described embodiments, the case where the registration error correction is performed for both the first registration error and the second registration error at a time by the registration error correction function has been described, but the present invention is not limited to this. For example, the second registration error correction, that is, only the correction of the registration error less than the inter-dot distance is performed before the factory shipment of the image forming apparatus 1, and the second registration error correction is performed at a predetermined timing such as when the power switch is turned on after shipment. One registration deviation correction, that is, a registration deviation correction in dot distance units may be performed.

  As an example of this case, a process of excluding the process of step 127 of the first registration misalignment correction processing program shown in FIG. 8 before shipment from the factory and performing only correction of misalignment less than dots in step 130 is performed. On the other hand, at the predetermined timing after shipment from the factory, the process of step 129 of the first registration deviation correction processing program is excluded, and the process of performing only the correction of the deviation amount in the inter-dot distance unit at step 130 is executed. The form to do can be illustrated.

  In this case, since the registration error correction process after factory shipment can be performed only by correcting the distance between dots, after the factory shipment, the software process as disclosed in Patent Document 1 as an example. Thus, the registration displacement correction process can be executed only by a mechanism for moving each recording head 34 in the nozzle row direction as shown in each of the above embodiments (in each of the above embodiments, a ball screw 64, a motor 65).

  In each of the above embodiments, the case where a plurality of optical sensors are used has been described. However, the present invention is not limited to this, and for example, as shown in FIG. 10 as an example, only a single optical sensor 67C is used. In addition, the moving unit 68 that moves the position of the optical sensor 67C in the nozzle row direction is used. When the amount of deviation cannot be detected, the position of the optical sensor is moved by the moving unit 68 to detect the amount of deviation again. Detection data is acquired for each position in a state where the optical sensor 67C is positioned at a plurality of positions different from each other, and the detection data obtained thereby can be used for deriving a deviation amount. In the case where there is an error, the amount of deviation may be detected using the detection data.

  Further, in each of the above embodiments, the case where the test pattern shown in FIG. 5 is applied has been described. However, the present invention is not limited to this, and for example, FIGS. 11 (A) to (C). It is good also as a form which applies what was shown in (1).

  FIG. 11A shows an example in which the number of nozzles that do not eject ink droplets in each line of the test pattern 80A is plural (two in the example shown in the figure). The form is effective when the dot diameter of the ink droplet is relatively small compared to the resolution of the optical sensor, and it is difficult for the optical sensor to detect a blank area due to non-ejection of the ink drop.

  11B and 11C show a predetermined number adjacent to the blank area corresponding to the area where the ink droplets are not ejected in each line of the test pattern 80B (shown in FIG. 11B). In the example, the dot is not formed on the side opposite to the blank area of one dot). In these forms, the ink is compared with the test pattern 80 according to each of the above embodiments. Consumption can be reduced.

  Further, in the test pattern 80 shown in FIG. 5 and the test patterns 80A to 80C shown in FIG. 11, the position of the nozzle 71 that does not discharge droplets from one end to the other end in the nozzle row direction X of the plurality of nozzles 71 is 1. A linear pattern extending in the nozzle row direction X is recorded by a plurality of recording heads 34 so as to be displaced by the nozzles by a predetermined number of lines. A plurality of predetermined nozzles may be shifted.

  In each of the above embodiments, the case where the ink droplet is applied as the droplet of the present invention has been described. However, the present invention is not limited to this, and for example, the treatment liquid is applied instead of the ink droplet. It is good also as a form to do.

  Further, in each of the above embodiments, the case where the present invention is applied to an image forming apparatus that forms a monochrome image has been described. However, the present invention is not limited to this, and the present invention forms a color image. It may be configured to be applied to an image forming apparatus.

  As an example of this case, a plurality of recording heads that eject ink droplets of different colors are applied as the recording head 34, while the reference data is stored in advance for each color by the ROM 54, A mode in which the deviation amount is derived using the reference data corresponding to the color of the ink droplet ejected by the recording head to be derived is exemplified. Also in this case, the same effects as those of the above embodiments can be obtained.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Paper feed conveyance part, 11 ... Processing liquid application part, 12 ... Image forming part, 13 ... Ink drying part, 14 ... Image fixing part, 15 ... Discharge part, 16 ... Stacking part, 17 ... Paper feeding unit, 18 ... roller, 19 ... conveying unit, 20 ... processing liquid coating drum, 21 ... holding member, 22 ... intermediate conveying drum, 23 ... image forming drum, 24 ... ink drying drum, 25 ... fixing drum, 26 ... Treatment liquid coating device, 27... Treatment liquid drying device, 28... Reservoir, 29 .. gravure roller, 30 .. rubber roller, 31 .. hot air nozzle, 32 .. infrared heater (IR heater), 33. Head (recording head), 35... Head unit, 36... Rotating shaft, 37... Intermediate transport section, 38... Hot air nozzle, 38 A. Fan / motor connection circuit, 39. ... Heating roller, 42 ... Fixing roller, 50 ... Fan / motor drive, 51 ... Communication interface, 52 ... System controller, 53 ... Image memory, 54 ... ROM, 55 ... Motor driver, 56 ... Heater driver, 57 ... Print controller 58 ... Image buffer memory, 59 ... Image processing device, 60 ... Head driver, 61 ... Recording medium transport motor, 62 ... ROM, 63 ... Motor driver, 66 ... A / D converter, 67A, 67B ... Optical sensor , 68 ... moving section, 70 ... head module, 70A ... support unit, 70B ... ink ejection surface, 71 ... nozzle, 80, 80A to 80C ... test pattern, 90 ... relative table, 99 ... host device, K ... recording medium

Claims (7)

A plurality of recording heads each having a nozzle row composed of a plurality of nozzles arranged in a nozzle row direction intersecting with the conveyance direction of the recording medium, and arranged along the conveyance direction;
A recording unit configured to record a test pattern for correcting a shift in the nozzle row direction between the plurality of recording heads on the recording medium using each of the plurality of recording heads;
Detection means for detecting the test pattern according to the conveyance of the recording medium at a predetermined detection position downstream of the plurality of recording heads in the conveyance direction;
Determination means for determining whether the detection result by the detection means is abnormal;
A change unit that changes the detection position of the detection unit to a position separated by a predetermined distance in the nozzle row direction when the determination unit determines that the abnormality is present;
When the determination unit determines that there is no abnormality, a deviation amount with respect to the nozzle row direction between the plurality of recording heads is derived based on the detection result by the detection unit, and the determination unit determines that the abnormality is present. A deriving unit for deriving a deviation amount in the nozzle row direction between the plurality of recording heads based on a detection result detected again by the detecting unit after being changed by the changing unit;
Correction means for correcting the deviation amount using the deviation amount derived by the derivation means;
A droplet discharge device comprising: The detection means comprises a plurality of sensors fixedly installed at different positions with respect to the nozzle row direction,
The liquid droplet ejection apparatus according to claim 1, wherein the changing unit changes the detection position by changing a sensor used for detecting the test pattern to any one of the plurality of sensors. The detection means comprises a sensor movable in the nozzle row direction,
The droplet discharge device according to claim 1, wherein the changing unit changes the detection position by moving the sensor. The recording means has, as the test pattern, a unit amount of nozzle positions at which the droplets are not ejected from one end to the other end of the plurality of nozzles in the nozzle row direction for each of the plurality of recording heads. The droplet according to any one of claims 1 to 3, wherein a linear pattern extending in the nozzle row direction by the plurality of nozzles is recorded on the recording medium by a predetermined number of lines so as to be displaced. Discharge device. 5. The droplet discharge apparatus according to claim 4, wherein the recording unit performs the recording so that a position in a nozzle row direction of a nozzle that does not discharge the droplet is shifted by one nozzle for each line. A plurality of recording heads each having a nozzle row composed of a plurality of nozzles arranged in a nozzle row direction intersecting with the conveyance direction of the recording medium, and arranged along the conveyance direction;
A recording unit configured to record a test pattern for correcting a shift in the nozzle row direction between the plurality of recording heads on the recording medium using each of the plurality of recording heads;
The test pattern is detected in accordance with the conveyance of the recording medium at a predetermined first position and second position, which are different from each other at least in the nozzle row direction downstream of the plurality of recording heads in the conveyance direction. Detection means;
Determining means for determining whether or not the detection result at the first position by the detecting means is abnormal;
If the determination means determines that there is no abnormality, a deviation amount in the nozzle row direction between the plurality of recording heads is derived based on the detection result at the first position by the detection means, and the determination means determines that there is an abnormality. Deriving means for deriving a deviation amount in the nozzle row direction between the plurality of recording heads based on a detection result at the second position by the detecting means;
Correction means for correcting the deviation amount using the deviation amount derived by the derivation means;
A droplet discharge device comprising: A registration of a droplet discharge device having a nozzle row composed of a plurality of nozzles arranged in a nozzle row direction intersecting with the conveyance direction of the recording medium, and having a plurality of recording heads arranged along the conveyance direction. A misalignment correction program,
A recording step of recording a test pattern for correcting a shift in the nozzle row direction between the plurality of recording heads on the recording medium using each of the plurality of recording heads;
A detection step of detecting the test pattern according to the conveyance of the recording medium at a predetermined detection position downstream of the plurality of recording heads in the conveyance direction;
A determination step of determining whether the detection result of the detection step is abnormal;
A change step of changing the detection position of the detection step to a position separated by a predetermined distance in the nozzle row direction when determined to be abnormal in the determination step;
If it is determined that the abnormality is not abnormal in the determination step, a deviation amount with respect to the nozzle row direction between the plurality of recording heads is derived based on the detection result detected in the detection step, and the abnormality is determined in the determination step. If the position is changed in the change step, the amount of deviation of the plurality of print heads in the nozzle row direction is derived based on the detection result detected again in the detection step. A derivation step;
A correction step for correcting the deviation amount using the deviation amount derived in the derivation step;
A registration error correction program for a droplet discharge device that causes a computer to execute

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