JP2017213773A - Control device for droplet discharge and image processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more quickly detect non-discharge from nozzles than execution of maintenance after the number of accidentally occurring non-discharge nozzles exceeds a certain number, and actively promote natural recovery.SOLUTION: A check pattern image 40 is provided in a clearance between main images 38. The image 40 is an image discharging a droplet from a nozzle selected every constant pitch, and the droplets are discharged from all nozzles by execution from a first line to an n-th line. The search for non-discharge nozzles becomes easy by reading out the image 40 by an ILS 36. Besides, a recovery pattern image 42 is provided in the clearance between the main images 38. The recovery pattern image 42 is basically an image for discharging the droplet while targeting a nozzle of accidental non-discharge predicted to be a temporal non-discharge. It becomes possible to more quickly inhibit a decrease in image quality by promoting recovery of the accidental non-discharge nozzle than by immediately recognizing it as a stationary non-discharge nozzle and performing interpolation processing by a DFE 16.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a droplet discharge control device and an image processing device.

  Conventionally, in a digital inkjet printer, (Procedure 1) test chart output, (Procedure 2) reading image information, (Procedure 3) analyzing image information, and (Procedure 4) correction processing are performed as defective nozzle correction processing. . Non-ejection nozzles are not forcibly ejected, and the drawing density of the nozzles in the vicinity of the non-ejection nozzles is increased so as to reduce the visibility of white streaky irregularities generated in the non-ejection nozzles.

  In Patent Literature 1, undischarge detection with a small processing load is performed between pages of images recorded on continuous paper (form paper), undischarge correction is performed, and when discharge detection exceeds a certain number, It describes that a maintenance process is performed, the detection result of the inter-page process is canceled and replaced with the undischarge detection result of the maintenance process.

JP 2014-012358 A

  In an ink jet printer, it is impossible to quickly respond to sudden non-ejection nozzles. Since the return process is not actively performed, there is a high possibility that the nozzle will become a steady non-ejection nozzle.

  The present invention relates to a droplet discharge control device that can detect more rapidly than when maintenance is performed after the number of non-discharge nozzles that occur unexpectedly exceeds a certain number, and can actively promote spontaneous recovery. An object is to obtain an image processing apparatus.

  According to the first aspect of the present invention, the droplet discharge amount is controlled for each nozzle in the effective image area provided along the transport direction while transporting the paper in the direction intersecting the direction in which the plurality of nozzles are arranged. And at least one of a main image recording control means for recording a main image, an inspection area for inspecting a droplet discharge state, and a return area forcibly discharging from a nozzle that has suddenly failed to discharge. Pattern recording control means for assigning to a non-effective image area different from the effective image area, recording an inspection pattern when the inspection area is assigned, and recording a return pattern when the return area is assigned. It is a droplet discharge control device.

  The invention according to claim 2 is the invention according to claim 1, wherein the effective image area is intermittently provided along a conveyance direction of a long sheet, and the non-effective image area is adjacent to the effective image area. It is provided in the gap between the image areas.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a part is selected from all the nozzles, and each of the plurality of ineffective image areas when the paper is transported is selected. On the other hand, the inspection patterns of all the nozzles are generated from a plurality of ineffective image areas by sequentially replacing the nozzles to be selected.

  According to a fourth aspect of the invention, in the invention of the third aspect, an inspection pattern including a target nozzle is used as the return pattern.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the target of the return pattern is on the left and right of the sudden non-ejection nozzle that suddenly becomes non-ejection. Droplets are ejected including adjacent normal nozzles.

  A sixth aspect of the present invention provides the main image recorded by the main image recording control means and the inspection pattern recorded by the pattern recording control means according to any one of the first to fifth aspects. And an image reading means for reading at least one of the return pattern, and an auxiliary processing means for executing auxiliary processing relating to droplet discharge control using an image read by the image reading means, the auxiliary When the main processing means reads the main image, it performs droplet amount adjustment control using at least the density distribution of the main image, and when it reads the inspection pattern, it does not depend on the recording state of the inspection pattern. The presence / absence of a discharge nozzle is determined.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the nozzle that is suddenly non-discharged as a target of the return pattern is a predetermined number of times. If non-ejection continues even if it is the target of the return pattern, it is designated as a steady non-ejection nozzle, and interpolation control of the amount of non-ejection droplets is executed by an adjacent nozzle.

  According to an eighth aspect of the present invention, in the invention of the seventh aspect, when the inspection pattern is read, if the nozzle that has been assumed to be a stationary non-ejection nozzle has recovered, the stationary non-ejection nozzle is designated. And is excluded from the droplet amount interpolation control.

  The invention according to claim 9 includes the droplet discharge control device according to any one of claims 1 to 8, and the received gradation data is at least relatively “large droplet”, “ It is converted into four stages of droplet discharge amount of “medium droplet”, “small droplet”, “no discharge”, and the main image is intermittently spaced at a predetermined interval while conveying the roll-shaped recording paper, and An image processing apparatus having an image recording unit that records at least one of an inspection pattern and a return pattern.

  According to the first aspect of the present invention, it is detected more quickly than when maintenance is performed after the number of non-ejection nozzles that occur unexpectedly exceeds a certain number, and spontaneous recovery is actively promoted. .

  According to the second aspect of the present invention, the effective image area and the ineffective image area are provided along the sheet conveyance direction.

  According to the third aspect of the present invention, the non-effective image area that is narrower than the effective image area is effectively used.

  According to the fourth aspect of the present invention, the storage capacity for storing the return pattern data is reduced rather than not substituting the inspection pattern.

  According to the fifth aspect of the present invention, sudden non-ejection of adjacent nozzles due to the sudden non-ejection nozzle is prevented.

  According to the sixth aspect of the present invention, after a series of main image recording is completed, it is possible to take measures against non-ejection more quickly than determining whether or not non-ejection has occurred.

  According to the seventh aspect of the present invention, the sudden non-ejecting nozzle and the steady non-ejecting nozzle are clearly classified.

  According to the eighth aspect of the invention, the nozzle capable of discharging is effectively used.

  According to the ninth aspect of the present invention, it is detected more rapidly than when maintenance is performed after the number of non-ejection nozzles that occur suddenly exceeds a certain number, and spontaneous recovery is actively promoted. .

It is a schematic block diagram which shows an example of the main components of the inkjet recording device which concerns on this Embodiment. (A) is a perspective view of a sheet conveyed by the ink jet recording apparatus according to the present embodiment, and (B) is an enlarged plan view of a range indicated by line IIB in FIG. 2 (A). 4 is a functional block diagram in which droplet discharge control based on main image information (droplet amount data) and non-discharge nozzle return control based on ILS monitoring are executed in the MCU according to the present embodiment. FIG. It is a conceptual diagram which shows the test | inspection pattern memorize | stored in the test | inspection pattern image memory | storage part of FIG. It is a flowchart which shows the image reading control routine in ILS concerning this Embodiment. It is a flowchart which shows the droplet discharge control routine to which the test | inspection and return function of the sudden non-discharge nozzle which concerns on this Embodiment was added. Timing chart showing a synchronization signal (particularly a sub-scanning synchronization signal) at the time of droplet discharge according to the present embodiment

(Outline of equipment)
FIG. 1 shows an inkjet recording apparatus 10 that is an image recording apparatus using droplets (sometimes referred to as ink droplets) as an image processing apparatus according to the present embodiment.

  The ink jet recording apparatus 10 includes a recording apparatus main body 14 connected to a communication network 12. A DFE (Digital Front End) 16 is connected to the communication line network 12. As a basic function, the DFE 16 includes a database 16A that stores image data obtained from the communication network 12 or a storage medium and managed in various types of formats. The DFE 16 converts the image data stored in the database 16 </ b> A into droplet amount data in the recording apparatus main body 14. The converted droplet amount data is sent to the recording apparatus main body 14 via the communication network 12. The database 16A may be physically external to the DFE 16.

  In the present embodiment, the recording apparatus main body 14 and the DFE 16 via the communication network 12 are used as the system configuration of the inkjet recording apparatus 10, but physically, the recording apparatus main body 14 and the DFE 16 are physically combined into a single unit. You may make it incorporate in (housing | casing).

  The recording apparatus main body 14 includes an MCU (Machine Control Unit) 18 connected to the communication network 12, an image recording unit 20, a paper feed roll 22, a discharge roll 24, and a transport roller 26. The MCU 18 includes a database 18A that stores various information including droplet volume data, change presence / absence data described later, and non-ejection nozzle information. The database 18A may be physically external to the MCU 18.

  The image recording unit 20 includes a head driving unit 28, a head 30 for discharging droplets, a drying driving unit 32, a drying unit 34, and an ILS (in-line sensor) 36 as an example of an image reading unit.

  The MCU 18 drives a paper conveyance motor (not shown), which is a conveyance system drive unit, to control the rotation of the conveyance roller 26 connected to the paper conveyance motor via a mechanism such as a gear.

  A long sheet P is wound around the sheet feeding roll 22 as a recording medium in the sheet conveying direction, and the sheet P moves in the direction of arrow A (sheet conveying direction) in FIG. 1 as the conveying roller 26 rotates. Be transported.

  The MCU 18 controls the head driving unit 28 based on the color information for each pixel of the image included in the image information stored in the information storage unit 18A, so that an image corresponding to the image information is displayed on the image recording surface of the paper P. Record. In the image recording in the present embodiment, while the paper P is being transported (the transport direction is the sub-scanning direction), the heads arranged in a line in the direction intersecting the transport direction of the paper P (main scanning direction) is used. This is realized by discharging droplets (ink droplets) from the nozzle.

  Specifically, the MCU 18 controls the head driving unit 28. Then, the head drive unit 28 records the droplets from the head 30 connected to the head drive unit 28 on the basis of the droplet discharge timing and the droplet amount instructed by the MCU 18 and records the image on the paper P. Dispense onto the surface.

  In the present embodiment, the amount of droplet is classified into four types of “large droplet”, “medium droplet”, “small droplet”, and “no discharge”. That is, the droplet amount data is represented by 2 bits.

  The head 30 includes four heads 30C, 30M, 30Y, and 30K corresponding to four colors of C (cyan), M (magenta), Y (yellow), and K (black), respectively. The corresponding color droplets are ejected from 30. The driving method for discharging droplets in the head 30 is not particularly limited, and a known method such as a so-called thermal method or piezoelectric method is applied.

  The drying drive unit 32 includes a switching element that controls on / off of a heat source (for example, a halogen lamp, a laser light emitting element, etc.) of the drying unit 34, and drives the switching element based on an instruction from the MCU 18. For example, when the heat source is a laser light emitting element, an FET (Field Effect Transistor) or the like can be applied as the switching element.

  The MCU 18 controls the drying drive unit 32 to irradiate a heat source (light) from the drying unit 34 toward the image recording surface of the paper P, and records on the paper P by heat generation (input heat amount) depending on the light. The droplets of the printed image are dried to fix the image on the paper P.

  Thereafter, the paper P is transported to the discharge roll 24 as the transport roller 26 rotates, and is wound around the discharge roll 24.

  When images are to be recorded on both sides of the paper P, the image recording unit 20 described above is overlapped (continuously arranged along the conveyance direction of the paper P), and the paper is transferred between the delivery of the image recording unit 20. The above process may be repeated by inverting P.

  In addition, there are water-based inks, oil-based inks that are inks whose solvent evaporates, ultraviolet curable inks, and the like in the droplets. In this embodiment, water-based inks are used.

  Here, an ILS 36 is arranged on the downstream side of the drying unit 34 and before the winding onto the discharge roll 24, and the image recorded on the paper P is read.

  For example, the ILS 36 is provided with a line sensor (photoelectric conversion elements (for example, CCD, CMOS, etc.) arranged in a line) in a direction (main scanning direction) that intersects the conveyance direction (sub-scanning direction) of the paper P. The two-dimensional image information recorded on the paper P is read by reading with the line sensor in accordance with the conveyance (main scanning) of the paper P, and the read image information is sent to the MCU 18.

  The MCU 18 corrects the image quality by feedback controlling the droplet amount data based on the image information (main image) from the ILS 36.

  Further, in the MCU 18, based on image information from the ILS 36 (an inspection pattern image and a return pattern image, which will be described later), for example, due to clogging of the nozzles of the head 30, droplets are not ejected (non-ejection), and in the sub-scanning direction. Whether or not streaks (white streaks, etc.) are continuously generated is monitored.

  When nozzle non-ejection is detected, based on the history information, is it a nozzle that is regularly non-ejecting (steady non-ejecting nozzle) or a nozzle that is suddenly non-ejecting (suddenly The non-ejection nozzles) are sorted and processing for dealing with each is executed.

  As a default, the steady non-discharge nozzle adjusts the droplet amount of a normal nozzle located around the normal non-discharge nozzle by a steady non-discharge nozzle interpolation LUT (not shown) provided on the DFE 16 side (usually, The control to interpolate is executed by increasing the droplet amount.

  Further, when a non-ejection nozzle is generated later while the processing is continued, the DFE 16 side is notified, and after changing the steady non-ejection nozzle interpolation LUT, control for interpolation is executed.

  Here, in the present embodiment, when a non-ejection nozzle occurs later, “return control” is performed in which a droplet ejection from the non-ejection nozzle is attempted immediately without being determined as a “steady non-ejection nozzle”. At the same time, “inspection control” is performed to monitor whether or not non-ejection has been resolved by return control.

  More specifically, as shown in FIG. 2A, the main image area 38 is printed on the paper P based on main image information received from the DFE 16 (see FIG. 1) along the transport direction.

  A gap is provided between the main image areas 38. In the present embodiment, an inspection pattern image area 40 and a return pattern image area 42 are provided in the gap.

  As an example, the gap is about 5 mm, and the paper P is conveyed at 80 meters per minute. The ILS 36 reads the image printed in the main image area 38 and obtains information for correcting the image quality (including monitoring of non-ejection nozzles), and in addition to the inspection pattern image printed in the inspection pattern image area 40. (And / or the return pattern image printed in the return pattern image area 42) is read to obtain information specialized for the inspection of the non-ejection nozzles.

  As shown in FIG. 2B, the inspection pattern image area 40 is controlled so that droplets are ejected from the nozzles at regular intervals, and the gap between the main image areas 38 is sequentially formed in the head 30 (see FIG. 1). ), So-called thinning-out ejection control is performed in which droplets are ejected from all the nozzles 30 in a plurality of inspection pattern image areas 40 by shifting the inspection pattern in the main scanning direction. .

  In the thinning discharge control, the number of inspection pattern image regions 40 required to complete the discharge of droplets from all the nozzles 30 may be set according to the pitch between adjacent nozzles 30 and the conveyance speed.

  Theoretically, it is possible to eject droplets from all the nozzles 30 in one inspection pattern image region 40. However, as a guideline, it is preferable to leave a pitch that does not overlap the droplets. .

  As shown in FIG. 2B, the return pattern image area 42 targets non-ejection (sudden non-ejection nozzle) at the nozzle 30 at a position different from the steady non-ejection nozzle based on the image read by the ILS 36. The droplet discharge control is executed.

  In this case, it is preferable that the droplet amount be the maximum (largely suitable discharge). In other words, the droplet discharge in the return pattern image region 42 is intended to restore the nozzle 30 that is temporarily clogged by eliminating the clogging by the droplet discharge momentum (for example, flow velocity or pressure) and returning it. Yes.

  FIG. 3 is a functional block diagram in which droplet discharge control based on main image information (droplet amount data) received from the DFE 16 and non-discharge nozzle return control based on ILS 36 monitoring are executed in the MCU 18. Each block in FIG. 3 is classified by function, and does not limit the hardware configuration of the MCU 18. For example, some or all of the functions may be processed in a so-called software manner (by executing a program).

  In the DFE 16 (see FIG. 1), droplet amount data as main image information is generated and sent to the receiving unit 50.

  There are, for example, relatively four types of droplet amount data, “large droplet”, “medium droplet”, “small droplet”, and “no discharge”, and are input to DFE 16 (or converted by DFE 16). It is set based on 8-bit gradation data (gradation data per recording dot recorded by one nozzle of the head 30).

  The receiving unit 50 is connected to an instruction unit 52 as an example of a main image recording control unit and a pattern recording control unit, and sends the received main image information to the instruction unit 52.

  The instruction unit 52 is connected to the temporary storage unit 54, and sends main image information (droplet amount data) received from the DFE 16 to the temporary storage unit 54. Accordingly, the main image information is stored in the main image storage unit 54A of the temporary storage unit 54, for example, in units of jobs.

  The instruction unit 52 is connected to the inspection pattern image reading unit 56 and the return target nozzle selection unit 58.

  The instruction unit 52 outputs an inspection pattern image reading instruction signal to the inspection pattern image reading unit 56 at the timing between each page when the main image information is sent to the temporary storage unit 54. Note that the timing between the pages does not have to alternate with the main image in terms of time, and the number of inspection pattern image information corresponding to the number of pages of the received main image (the number of main images-1) is simultaneously obtained. You may instruct to read.

  An inspection pattern image storage unit 60 is connected to the inspection pattern image reading unit 56.

  As shown in FIG. 4, the test pattern image storage unit 60 stores the test pattern image information of liquid droplet ejection in which nozzles at predetermined pitches are selected, in the row direction from 1 to n, respectively. It is stored in a shifted form.

  For example, one inspection pattern image is one row (one row from the first row to the n-th row), and each is assigned to the inspection pattern image region 40 in the gap between the main image regions 38. (See FIG. 2).

  As shown in FIG. 3, the inspection pattern image reading unit 56 is connected to the temporary storage unit 54. The inspection pattern image reading unit 56 reads, for example, inspection pattern image information corresponding to the number of pages of the main image of one job from the inspection pattern image storage unit 60 and stores the inspection pattern image in the temporary storage unit 54. Store in part 54B.

  On the other hand, the instruction unit 52 outputs a return pattern generation instruction signal to the return target nozzle selection unit 58 at the timing between each page when the main image information is sent to the temporary storage unit 54.

  The return target nozzle selection unit 58 is connected to the sudden non-ejection nozzle position storage unit 61, and when receiving the return pattern generation instruction signal from the instruction unit 52, the sudden non-ejection nozzle position storage unit 61 receives the sudden non-ejection nozzle position storage unit 61. Get location information.

  The sudden non-discharge nozzle position storage unit 61 is connected to the sudden non-discharge nozzle position specifying unit 62. Further, the sudden non-ejecting nozzle position specifying unit 62 is connected to the read image analyzing unit 64. The read image analysis unit 64 analyzes the main image information read by the ILS 36. As one of the analyses, the density information is compared with a predetermined threshold value, and the presence / absence of white streaks in the sub-scanning direction due to droplet non-ejection is analyzed.

  The analysis result obtained by analyzing the main image in the read image analysis unit 64 is sent to a droplet amount data correction unit (not shown) as feedback control of droplet amount data, and the analysis result obtained by analyzing the inspection pattern image and the return pattern image Is sent to the sudden ejection failure nozzle position specifying unit 62.

  Further, a steady non-discharge nozzle position storage unit 66 is connected to the sudden non-discharge nozzle position specifying unit 62.

  Here, the sudden non-ejecting nozzle position specifying unit 62 specifies a position excluding the steady non-ejecting nozzle position from the non-ejecting nozzle position obtained from the analysis result from the read image analyzing unit 64 as the sudden non-ejecting nozzle position. . The identified sudden ejection failure nozzle position information is sent to the sudden ejection failure nozzle position storage unit 61 and updated and stored.

  Although not shown, the nozzle determined to be a sudden non-discharge nozzle continuously for a plurality of times based on the history of update storage status of the sudden non-discharge nozzle position storage unit 61 is changed to a steady non-discharge nozzle. May be.

  In this case, the storage information in the steady non-ejection nozzle position storage unit 66 is updated, the addition of the steady non-ejection nozzle is notified to the DFE 16, and the interpolation control by the steady non-ejection nozzle interpolation LUT on the DFE 16 side. It is necessary to redo.

  The return target nozzle selection unit 58 selects the return target nozzle from the position information of the sudden non-discharge nozzle stored in the sudden non-discharge nozzle position storage unit 61 and sends it to the return pattern image generation unit 68.

  The return pattern image generation unit 68 generates a return pattern image in which droplets are ejected from the selected return target nozzle.

  The return pattern image generation unit 68 is connected to the temporary storage unit 54, and stores the return pattern image in the return pattern image storage unit 54 </ b> C of the temporary storage unit 54.

  The temporary storage unit 54 is connected to the image reading unit 70.

  The image reading unit 70 receives a synchronization signal from the synchronization signal generation unit 72. Upon receiving the synchronization signal, the image reading unit 70 reads an image from the temporary storage unit 54, and is an example of a main image recording control unit and a pattern recording control unit. To the droplet discharge execution instructing unit 74 (details will be described later).

  The synchronization signal generation unit 72 is connected to the main image synchronization signal generation unit 76.

  The main image synchronization signal generation unit 76 generates a main image synchronization signal (sub-scanning synchronization signal and main scanning synchronization signal) based on, for example, a print instruction from a UI (not shown) or the like. The generated synchronization signal of the main image is sent to the synchronization signal generator 72.

  As the synchronization signal transmitted from the synchronization signal generation unit 72 to the image reading unit 70, a main image synchronization signal, an inspection pattern image synchronization signal, and a return pattern image synchronization signal are selectively transmitted.

(Print execution control based on various synchronization signals)
When the image reading unit 70 receives the main image synchronization signal, the main image is read from the main image storage unit 54 </ b> A of the temporary storage unit 54 and sent to the droplet discharge execution instruction unit 74. The droplet discharge execution instructing unit 74 controls the head driving unit 28 to discharge droplets from the nozzle 30 and execute printing of the main image.

  When the image reading unit 70 receives the inspection pattern image synchronization signal, the inspection pattern image is read from the inspection pattern image storage unit 54B of the temporary storage unit 54 and sent to the droplet discharge execution instruction unit 74. The droplet discharge execution instructing unit 74 controls the head driving unit 28 to discharge the droplets from the nozzles 30 and print the inspection pattern image.

  When the image reading unit 70 receives the return pattern image synchronization signal, the return pattern image is read from the return pattern image storage unit 54 </ b> C of the temporary storage unit 54 and sent to the droplet discharge execution instruction unit 74. The droplet discharge execution instructing unit 74 controls the head driving unit 28 to discharge droplets from the nozzles 30 and execute printing of the return pattern image.

  The operation of the present embodiment will be described below.

  In the ink jet recording apparatus 10 of the present embodiment, the image data received by the DFE 16 is converted into reference droplet amount data representing the droplet amount and sent to the MCU 18.

  The MCU 18 controls a transport drive system (not shown) to pull out the paper P wound up by the paper feed roll 22 from the uppermost layer and transport it at a constant speed along the direction of arrow A in FIG.

  Along with this conveyance, the MCU 18 controls the head driving unit 28 of the image recording unit 20, and droplets are ejected from the nozzles of the head 30 with a droplet amount based on image data, thereby recording an image.

  The paper P on which the image is recorded is sent to the drying unit 34 and dried.

  Thereafter, when the recording paper P passes through the ILS 36, the recorded image is read and used as information for feedback correction such as image quality correction, for example. The recording paper P on which image recording has been completed is wound up on the paper discharge roll 24.

  In the present embodiment, the image read by the ILS 36 is applied to the monitoring of the non-ejection nozzle.

  That is, for example, when a non-ejection nozzle that does not eject droplets due to clogging of the nozzles of the head 30 occurs, the interpolation (DFE 16) causes the dots (pixels) to be recorded by the non-ejection nozzle to be set to the surrounding nozzles (adjacent nozzles). ) Is recorded so as to be interpolated to suppress deterioration in image quality.

  By the way, in the non-ejection nozzles, there are nozzles that are regularly non-ejection and nozzles that temporarily (disruptively) non-ejection.

  Nozzles that are normally non-discharge (steady non-discharge nozzles) may be interpolated by the interpolation processing in the DFE 16, but nozzles that are suddenly non-discharge (sudden non-discharge nozzles) are discharged from the original. It may be possible.

  Therefore, in the present embodiment, the sudden non-discharge nozzle is extracted from the non-discharge nozzle, the liquid droplet is projected in the area other than the main image area 38 (return pattern image area 42), and the return (droplet re-discharge) is performed. I was encouraged.

  Further, in the present embodiment, in the region other than the main image region 38 (inspection pattern image region 40), the droplets are projected for all the nozzles, and the droplet discharge state is inspected.

  In the present embodiment, the sheet P is a long so-called form sheet, and is fed continuously unlike a cut sheet. Therefore, the sheet interval is several mm shorter than that of a cut sheet (for example, an interval of 5 mm). ), An image (two-dimensional image) is recorded. Therefore, an inspection pattern image area 40 and a return pattern image area 42 are provided in a slight gap between the main image areas 38 for the purpose of inspecting and returning the non-ejection nozzles, and the inspection pattern printed on the inspection pattern image area 40 is provided. The image and the return pattern image printed in the return pattern image area 42 are read by the ILS 36 to monitor the non-ejection nozzles.

(Identification of sudden non-discharge nozzle)
FIG. 5 is a flowchart showing an image reading control routine in the ILS 36 incorporated in the recording apparatus main body 14.

  In step 100, it is determined whether it is an image reading time. Here, since the reading area designated as the image reading time also serves as image quality correction, the main image area 38 is targeted.

  In addition, when specializing in the identification of the sudden ejection failure nozzle, the inspection pattern image area 40 may be targeted.

  If a negative determination is made in step 100, this routine ends. If an affirmative determination is made in step 100, the process proceeds to step 102, the image recorded on the paper P is read, and the process proceeds to step 104.

  In step 104, image analysis is performed. In this image analysis, various analyzes such as calculating the density value of the read image to generate a density spectrum distribution or comparing the calculated density value with a predetermined threshold value are executed as necessary. Is done. That is, the main purpose of the ILS 36 is to collect information for feedback control of image correction.

  When the image reading time is set to the inspection pattern image area 40, it is specialized to specify the sudden ejection failure nozzle.

  In the next step 106, a part of the analysis result of the ILS 36 is used to search for irregular stripes having regularity in the sub-scanning direction, and the process proceeds to step 108.

  In step 108, if there are streaky irregularities as a result of the search, it is determined that nozzle clogging (including bending) of the head 30 is a factor, the non-ejection nozzle position is specified, and then the process proceeds to step 110. Then, the steady non-discharge nozzle position information is read from the steady non-discharge nozzle position storage unit 66 (see FIG. 3), and the process proceeds to Step 112.

  In step 112, the position excluding the position of the steady non-discharge nozzle read in step 110 from the position of the non-discharge nozzle specified in step 108 is specified as a sudden non-discharge nozzle position, and the process proceeds to step 114.

  In step 114, the information stored in the sudden ejection failure nozzle position storage unit 61 is updated and stored, and this routine ends.

(Droplet ejection control)
FIG. 6 is a flowchart showing a droplet discharge control routine to which an inspection and return function for a sudden non-discharge nozzle according to the present embodiment is added.

  In step 120, it is determined whether droplet amount data has been received from the DFE 16. The droplet amount data is relatively four types (2 bits) of “large droplet”, “medium droplet”, “small droplet”, and “no discharge”.

  If a negative determination is made in step 120, this routine ends. If an affirmative determination is made in step 120, the routine proceeds to step 122, where it is determined whether or not there has been a print instruction from the UI or the like. If a negative determination is made in step 122, the process proceeds to step 124, where it is determined whether or not there has been a print cancel instruction from the UI or the like. If a negative determination is made, the process returns to step 122, and either step 122 or step 124 is determined. Steps 122 and 124 are repeated until an affirmative determination is made.

  If the determination at step 124 is affirmative, this routine ends.

  On the other hand, if an affirmative determination is made in step 122, the process proceeds to step 126 to generate a main image synchronization signal, and the process proceeds to step 128.

  As shown in FIG. 7, a sub-scanning synchronization signal and a main-scanning synchronization signal are generated as the main image synchronization signal. The sub-scanning synchronization signal includes a signal indicating the start of sub-scanning and a signal indicating an effective period during sub-scanning (hereinafter referred to as “effective main image sub-scanning synchronization signal”).

  In step 128, an inspection pattern image synchronization signal is generated, and the process proceeds to step 130.

  As shown in FIG. 7, the inspection pattern image synchronization signal is generated between the effective main image sub-scan synchronization signal. As a result, the inspection pattern image area 40 is secured in the gap between the main image areas 38 of the paper P.

  In step 130, the sudden non-discharge nozzle position information is read, and then the process proceeds to step 132 to determine whether or not there is a sudden non-discharge nozzle.

  If an affirmative determination is made in step 132, it is determined that there is a sudden non-ejection nozzle, and the routine proceeds to step 134 to specify the sudden non-ejection nozzle position, and then the routine proceeds to step 136 to generate a return pattern image synchronization signal. Then, the process proceeds to step 138.

  If a negative determination is made in step 132, it is determined that there is no sudden non-ejecting nozzle, and the process proceeds to step 138.

  As shown in FIG. 7, the return pattern image synchronization signal is generated between the effective main image sub-scan synchronization signal. In this case, the return pattern image area 42 is a gap between the main image areas 38 of the paper P, and is secured downstream of the inspection pattern image area 40 in the transport direction of the paper P.

  In step 138, a read image is selected. That is, there are a main image, an inspection pattern image, and a return pattern image as images to be printed by ejecting liquid droplets. At least the main image is selected, and an inspection pattern image and / or a return pattern image is selected as necessary. Is done.

  As shown in FIG. 4, the inspection pattern image is selected from the inspection pattern images stored in the inspection pattern image storage unit 60.

  For example, by assigning each of the gaps between the main image areas 38 from the 1st line to the nth line, the liquid for the inspection from all the nozzles can be obtained by printing the inspection pattern image n times. Droplet ejection (printing) ends.

  The inspection pattern image basically repeats from the first line to the nth line.

  The return pattern image is generated so as to perform droplet discharge specialized for the sudden non-discharge nozzle specified in step 134. That is, if there are three sudden non-ejection nozzles, droplet ejection (printing) is performed from the three nozzles as shown in FIG.

  Note that an inspection pattern image including a sudden ejection failure nozzle may be used instead of generating a return pattern image.

  In the next step 140, the image selected in step 138 is read out, and then the process proceeds to step 142 to execute droplet ejection to the head driving unit 28 for each image based on the synchronization signal in FIG. The routine ends.

  According to the present embodiment, the inspection pattern image area 40 is provided in the gap between the main image areas 38. As shown in FIG. 4, the inspection pattern image is an image in which droplets are ejected from nozzles selected at fixed pitches, and droplets from all nozzles are obtained by executing from the first row to the n-th row. Discharging is performed.

  Reading the inspection pattern image with the ILS 36 facilitates the search for the non-ejection nozzle.

  Further, according to the present embodiment, the return pattern image 40 is provided in the gap between the main image areas 38. The return pattern image area 40 is basically an image for ejecting droplets targeting a sudden non-ejection nozzle that is predicted to be temporary non-ejection.

  It is possible to eliminate the clogging of the nozzle 30 that is temporarily clogged with the momentum of droplet discharge (for example, flow rate or pressure), with the maximum droplet amount (largely suitable discharge).

  The sudden non-discharge nozzle is a nozzle excluding the steady non-discharge nozzles among the non-discharge nozzles obtained as a result of the analysis of the inspection pattern image 40 read by the ILS 36. This sudden non-ejecting nozzle is immediately recognized as a steady non-ejecting nozzle, and it is possible to promptly cope with the suppression of image quality degradation by urging the return rather than performing interpolation processing by the DFE 16.

  In addition, in the case of temporary non-ejection, the corresponding nozzle can be effectively used without being unused.

(Modification of inspection pattern and return pattern)
In FIG. 2, the inspection pattern image area 40 and the return pattern image area 42 are clearly separated, but the inspection pattern image area 40 may be continuously executed as necessary.

  In addition, one gap may be formed as one pattern from the situation of the gap between the main image areas 38 (as an example, 5 mm) and the conveyance speed (as an example, 80 meters per minute). For example, an alternate arrangement in which a specific gap is set as the inspection pattern image area 40 and the next gap is set as the return pattern image area 42 may be employed.

  When the return pattern image area 42 is unnecessary (when no sudden ejection failure nozzle is present), both of the two areas of the gap may be used as the inspection pattern area 40.

  Furthermore, the return pattern image area 42 may be replaced with an inspection pattern image area 40 including a sudden ejection failure nozzle.

  Further, when the number of sudden non-ejecting nozzles exceeds a predetermined number, droplets may be ejected simultaneously from all the nozzles as a return pattern image in the return pattern image area 42. In the case of simultaneous discharge, whether or not the sudden non-ejecting nozzle has returned is preferably discharged again in the return pattern image area 42 with a return pattern image targeting the non-ejecting nozzle.

DESCRIPTION OF SYMBOLS 10 Inkjet recording device 12 Communication network 14 Recording device main body 16 DFE (Digital Front End)
18 MCU (Machine Control Unit)
DESCRIPTION OF SYMBOLS 20 Image recording part 22 Paper feed roll 24 Discharge roll 26 Conveyance roller 28 Head drive part 30 (30C, 30M, 30Y, 30K) Head 32 Drying drive part 34 Drying part 36 ILS (in-line sensor)
38 Main image area 40 Inspection pattern image area 42 Return pattern image area 50 Accepting section 52 Instruction section 54 Temporary storage section 54A Main image storage section 54B Inspection pattern image storage section 54C Return pattern image storage section 56 Inspection pattern image reading section 58 Return target Nozzle selection unit 60 Inspection pattern image storage unit 61 Sudden non-discharge nozzle position storage unit 62 Sudden non-discharge nozzle position specifying unit 64 Read image analysis unit 66 Steady non-discharge nozzle position storage unit 68 Return pattern image generation unit 70 Image reading unit 72 Synchronization Signal generation unit 74 Droplet discharge execution instruction unit 76 Main image synchronization signal generation unit

Claims (9)

A main image that records the main image by controlling the droplet discharge amount for each nozzle in an effective image area provided along the transport direction while transporting the paper in a direction intersecting the direction in which the plurality of nozzles are arranged. Recording control means;
Assign at least one of an inspection area for inspecting the state of droplet ejection and a return area forcibly ejecting from a nozzle that has suddenly failed to be ejected to a non-effective image area different from the effective image area Pattern recording control means for recording an inspection pattern when an inspection area is assigned, and for recording a return pattern when a return area is assigned;
A droplet discharge control apparatus comprising:   The droplet discharge control device according to claim 1, wherein the effective image area is intermittently provided along a conveyance direction of a long sheet, and the non-effective image area is provided in a gap between the adjacent effective image areas. .   By selecting a part from all the nozzles and sequentially replacing the nozzles to be selected for each of the plurality of ineffective image areas when the paper is transported, The droplet discharge control device according to claim 1 or 2, wherein an inspection pattern is generated.   The droplet discharge control device according to claim 3, wherein an inspection pattern including a target nozzle is used as the return pattern.   5. The droplet according to claim 1, wherein the target of the return pattern is to eject droplets including normal nozzles adjacent to the left and right of the sudden ejection failure nozzle that has suddenly failed ejection. Droplet discharge control device. Image reading means for reading the main image recorded by the main image recording control means and at least one of the inspection pattern and the return pattern recorded by the pattern recording control means;
An auxiliary processing unit that executes an auxiliary process related to droplet discharge control using the image read by the image reading unit;
The auxiliary processing means comprises:
When the main image is read, the droplet amount adjustment control is executed using at least the density distribution of the main image, and
6. The droplet discharge control device according to claim 1, wherein when the inspection pattern is read, the presence or absence of a non-ejection nozzle is determined based on a recording state of the inspection pattern.   If a nozzle that has suddenly failed to become the target of the return pattern continues to be non-discharged even if it becomes the target of the predetermined number of return patterns, it is designated as a stationary non-discharge nozzle and adjacent The liquid droplet ejection control apparatus according to claim 1, wherein interpolation control of a non-ejection liquid droplet amount is executed by a nozzle that performs ejection.   The reading of the inspection pattern, when a nozzle that has been a stationary non-ejection nozzle has recovered, the designation of the stationary non-ejection nozzle is canceled and excluded from the droplet amount interpolation control. Droplet discharge control device. A droplet discharge control device according to any one of claims 1 to 8, comprising:
The received gradation data is converted into at least four stages of droplet ejection amounts, “Large droplet”, “Medium droplet”, “Small droplet”, and “No ejection”, and the roll-shaped recording paper is conveyed. An image processing apparatus having an image recording unit that intermittently records at least one of a main image and an inspection pattern or a return pattern at predetermined intervals.

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