JP2023040724A - Recording device, recording method and program - Google Patents

Abstract

To provide a technology that can suppress generation of burnt deposit in a discharge defective nozzle caused in a recording head.SOLUTION: Recording means 30 includes a plurality of nozzles n including an electric heat conversion device and performs recording on a recording medium P by performing predetermined ink discharge from the nozzles with the heat generated by the electric heat conversion device. Detection means 9A detects a discharge defective nozzle that fails predetermined ink discharge with the heat generated by the electric heat conversion device from the plurality of nozzles n. Control means 13 and HC2 reduces power to be supplied to the electric heat conversion device of the discharge defective nozzle so as to be less than normal power to be supplied to an electric heat conversion device of a normal nozzle that normally performs predetermined ink discharge with the heat generated by the electric heat conversion device.SELECTED DRAWING: Figure 14

Description

The present invention relates to a recording apparatus, a recording method, and a recording medium having a recording head that ejects ink using electrothermal transducers.

Japanese Patent Application Laid-Open No. 2002-200001 discloses a technique of specifying a defective area on a transfer member and changing the image forming position so that the defective area is not included. According to this technique, even if a defective area is included inside the transfer image forming area corresponding to the size of the recording medium, the recording operation can be continued depending on the position of the image, thereby preventing deterioration in recording efficiency. can be suppressed.

JP 2018-192678 A

The technique disclosed in Japanese Patent Application Laid-Open No. 2002-200003 is a technique for reducing the influence of a defective area that occurs on a transfer body, and does not consider the influence that occurs when an ejection failure occurs in a nozzle of a recording head. In the thermal ink jet type recording head, ink supply to the nozzles may be insufficient due to inclusion of bubbles or the like, resulting in ejection failure. If image formation is continued in a state in which ejection failure has occurred in the nozzle, defects in the image will occur and foreign matter called kogation will occur due to the heat generated by the electrothermal conversion element provided in the nozzle, and the ejection performance of the nozzle will be affected. may decline further. When burnt deposits occur inside the nozzle, there is a possibility that the ejection performance will not recover even if a maintenance process or the like is performed to forcibly flow the ink inside the nozzle, and replacement will be necessary.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a technique capable of suppressing the occurrence of burnt deposits in nozzles with ejection failure that occur in a print head.

The present invention comprises a plurality of nozzles having electrothermal conversion elements, and recording means for recording on a recording medium by discharging predetermined ink from the nozzles by heat generated by the electrothermal conversion elements, and the electrothermal conversion elements. detection means for detecting, from among the plurality of nozzles, defective ejection nozzles from which the prescribed ink ejection is not normally performed due to heat generated by the electrothermal conversion element; and control means for reducing power supplied to the electrothermal conversion element of the ejection failure nozzle from a normal amount of power supplied to the electrothermal conversion element.

According to the present invention, it is possible to suppress the occurrence of burnt deposits in the ejection failure nozzles of the print head.

1 is a schematic diagram of a recording system; FIG. 3 is a perspective view of a recording unit; FIG. FIG. 4 is a diagram showing the arrangement of nozzles and the arrangement of dots of the print head; FIG. 4 is an explanatory diagram of a displacement mode of a recording unit; 3 is a block diagram of a control system of the recording system; FIG. FIG. 10 is a diagram showing an example of an image subjected to imposition processing; 4 is a flow chart showing a procedure of image processing; 2 is a block diagram showing the configuration of an engine controller; FIG. FIG. 4 is an explanatory diagram showing an operation example of the recording system; FIG. 4 is an explanatory diagram showing an operation example of the recording system; 1A and 1B are diagrams illustrating an example of a recording head and a printed matter; FIG. FIG. 3 is a diagram showing the positional relationship between a printed matter and a defective area of a print head; 4 is a flowchart showing the procedure of overall processing executed in the first embodiment; FIG. 3 is a diagram showing the positional relationship between a printed matter and a defective area of a print head; 7 is a flow chart showing a process of determining whether or not overlap between a defective area and an image forming area can be avoided; FIG. 10 is a diagram showing the positional relationship between an image forming area and a defective area in the second embodiment; FIG. 11 is a diagram showing an example of a serial type recording method in the fifth embodiment; FIG. 11 is a diagram showing another example of a serial type recording method in the fifth embodiment; FIG. 12 is a diagram showing an example of a printed matter for explaining the sixth embodiment; FIG.

Embodiments of the present invention will be described below with reference to the drawings. In each figure, arrows X and Y indicate horizontal directions and are perpendicular to each other. Arrow Z indicates the up-down direction.

[First Embodiment]
<Recording system>
FIG. 1 is a front view schematically showing a recording system 1 according to one embodiment of the invention. The recording system 1 is a sheet-fed inkjet printer that transfers an ink image onto a recording medium P via a transfer body 2 to manufacture a recorded matter P′. The recording system 1 includes a recording device 1A and a conveying device 1B. In this embodiment, the X direction, Y direction, and Z direction indicate the width direction (full length direction), depth direction, and height direction of the recording system 1, respectively. The recording medium P is conveyed in the X direction.

"Recording" includes not only the formation of meaningful information such as characters and figures, but also the formation of images, patterns, patterns, etc. on recording media, regardless of significance, or the processing of recording media. It also includes the case of doing so. In addition, it does not matter whether or not the "record" is materialized so that humans can visually perceive it. Further, in this embodiment, sheet-like paper is assumed as the "recording medium", but cloth, plastic film, or the like may also be used.

Although there are no particular limitations on the components of the ink, this embodiment assumes the case of using a water-based pigment ink containing a pigment as a coloring material, water, and a resin.

<Recording device>
The recording apparatus 1A includes a recording unit 3, a transfer unit 4 and peripheral units 5A-5D, and a supply unit 6. FIG.

<Recording unit>
The recording unit 3 includes a plurality of recording heads (recording means) 30 and a carriage 31 . The recording unit 3 will be described with reference to FIGS. 1 to 3. FIG. FIG. 2 is a perspective view of the recording unit 3. FIG. The recording head 30 ejects liquid ink onto the transfer body 2 to form an ink image of a recording image on the transfer body 2 .

The printing apparatus 1A according to the present embodiment is a full-line type printing apparatus having a full-line head (full multi-head) extending in the Y direction as the printing head 30 . The recording head 30 has nozzles n arranged in a range that covers the width of the image recording area of the maximum size recording medium that can be used. The recording head 30 has an ink discharge surface with nozzles on its lower surface, and the ink discharge surface faces the surface of the transfer body 2 with a minute gap (for example, several millimeters) therebetween. In the case of this embodiment, the transfer body 2 is configured to cyclically move on a circular orbit, so the plurality of recording heads 30 are arranged radially.

FIG. 3A is a diagram showing the arrangement of nozzles of the recording head 30. FIG. As shown in FIG. 3A, the recording head 30 has a plurality of ejection substrates 301, 302, 303, 304, . . . arranged in the Y direction. Eight rows of nozzles a to h extending in the nozzle arrangement direction (Y direction) are arranged on each ejection substrate. The nozzle spacing in the Y direction for each nozzle row a-h is 1200 dpi. Here, the nozzle rows a to h are arranged in the X direction with a spacing of 1/4 of 1200 dpi in the Y direction.

In the print head 30 shown in FIG. 3A, adjacent ejection substrates (e.g., ejection substrate 301 and ejection substrate 302) are arranged so as to partially overlap in the Y direction. Each of the nozzle rows (longitudinal columns) i to l in the vertical direction (X direction) of the nozzles in this portion has four nozzles in the X direction. Two nozzles are present in each of the columns m to p of the nozzles located in the portions (non-overlapping portions) of the ejection substrates 302 where the adjacent ejection substrates 301 do not overlap. FIG. 3B is a diagram showing the dot arrangement of the nozzle check pattern printed by the print head.

Each of the plurality of nozzles provided on each of the ejection substrates 301, 302, 303, 304, . . . described above is provided with an ejection element. The ejecting element is, for example, an element that generates pressure in a nozzle to eject ink in the nozzle, and a known inkjet head technology for an inkjet printer can be applied. In this embodiment, an electrothermal conversion element that converts supplied electrical energy into thermal energy to generate heat is used as the ejection element. Electrothermal transducers are suitable for recording apparatuses that perform high-speed, high-density recording. For this reason, the printing apparatus 1A in this embodiment is provided with a thermal ink jet printing head equipped with an electrothermal conversion element (heater). Note that in a thermal ink jet recording head, an electric pulse is supplied to an ejection element provided in each nozzle to drive (heat) a heater and eject ink. That is, the electric pulse supplied to the electrothermal conversion element of the nozzle serves as an ejection command for ejecting ink. In the following description, the supply of electric pulses to the electrothermal transducers corresponding to the nozzles is simply referred to as the supply of electric pulses to the nozzles.

As described above, a plurality of recording heads 30 having a plurality of ejection substrates 301, 302, 303, 304, . The plurality of print heads 30 are arranged at regular intervals in a direction intersecting the direction in which the nozzles are arranged. A color image can be formed on the transfer body 2 by ejecting different colors of ink from the plurality of recording heads 30 onto the transfer body 2 . In this embodiment, nine recording heads 30 are provided. Each recording head 30 ejects different types of ink. Different types of inks are, for example, inks with different coloring materials, such as yellow ink, magenta ink, cyan ink, and black ink. One recording head 30 ejects one type of ink, but one recording head 30 may be configured to eject a plurality of types of ink. When a plurality of recording heads 30 are provided in this manner, some of them may eject ink containing no coloring material (for example, clear ink). Furthermore, it is possible to provide a recording head capable of ejecting a transparent transfer liquid that facilitates the transfer of the ink applied to the transfer body 2 to the recording paper.

A carriage 31 supports a plurality of printheads 30 . Each recording head 30 is fixed to a carriage 31 at the end on the side of the ink ejection surface. As a result, the gap between the ink ejection surface and the surface of the transfer body 2 can be maintained more precisely. The carriage 31 is configured to be displaceable while mounting the recording head 30 under the guidance of the guide member RL. In the case of this embodiment, the guide members RL are rail members extending in the Y direction, and are provided as a pair in the X direction, spaced apart from each other. A slide portion 32 is provided on each side portion of the carriage 31 in the X direction. The slide portion 32 engages with the guide member RL and slides along the guide member RL in the Y direction.

FIG. 4 shows a displacement mode of the recording unit 3, and is a diagram schematically showing the right side of the recording system 1. As shown in FIG. A recovery unit 12 is provided at the rear of the recording system 1 . The recovery unit 12 has a mechanism for recovering the ejection performance of the recording head 30 . Examples of such a mechanism include a cap mechanism that caps the ink ejection surface of the recording head 30, a wiper mechanism that wipes the ink ejection surface, and a suction mechanism that sucks the ink in the recording head 30 from the ink ejection surface with a negative pressure. be able to.

The guide member RL extends from the side of the transfer member 2 to the recovery unit 12 . The recording unit 3 is guided by a guide member RL and can be displaced between an ejection position POS1 indicated by a solid line and a recovery position POS3 indicated by a broken line. is moved by

The ejection position POS<b>1 is the position where the recording unit 3 ejects ink onto the transfer body 2 , and the position where the ink ejection surface of the recording head 30 faces the surface of the transfer body 2 . The recovery position POS3 is a position retreated from the ejection position POS1, and is a position where the recording unit 3 is positioned above the recovery unit 12. FIG.

The recovery unit 12 can perform recovery processing for the printhead 30 when the recording unit 3 is positioned at the recovery position POS3. In this embodiment, the recovery process can be executed even while the recording unit 3 is moving before reaching the recovery position POS3. Further, there is a preliminary recovery position POS2 between the ejection position POS1 and the recovery position POS3. The recovery unit 12 can perform preliminary recovery processing for the print head 30 at the preliminary recovery position POS2 while the print head 30 is moving from the ejection position POS1 to the recovery position POS3.

<Transfer unit>
The transfer unit 4 will be described with reference to FIG. The transfer unit 4 includes a transfer drum (transfer cylinder) 41 and an impression cylinder 42 . These cylinders are rotating bodies that rotate around a rotation axis extending in the Y direction, and have cylindrical outer peripheral surfaces (surfaces). In FIG. 1, the arrows shown in the transfer drum 41 and the impression cylinder 42 indicate their rotational directions, the transfer drum 41 rotating clockwise and the impression cylinder 42 rotating counterclockwise.

The transfer drum 41 is a support that supports the transfer body 2 on its outer peripheral surface. The transfer body 2 is provided on the outer peripheral surface of the transfer drum 41 continuously or intermittently in the circumferential direction. When provided continuously, the transfer member 2 is formed in an endless strip. When intermittently provided, the transfer body 2 is formed in a belt-like shape with ends divided into a plurality of segments, and each segment can be arranged in an arc shape on the outer peripheral surface of the transfer drum 41 at equal pitches.

The rotation of the transfer drum 41 causes the transfer body 2 to cyclically move on a circular orbit. Depending on the rotation phase of the transfer drum 41, the position of the transfer body 2 can be distinguished into a pre-ejection processing region R1, an ejection region R2, post-ejection processing regions R3 and R4, a transfer region R5, and a post-transfer processing region R6. The transfer member 2 cyclically passes through these regions.

The pre-ejection treatment area R1 is an area in which pretreatment is performed on the transfer body 2 before ink is ejected by the recording unit 3, and is an area in which the peripheral unit 5A performs processing. In the case of this embodiment, a reaction liquid is applied. The ejection area R2 is a formation area where the recording unit 3 ejects ink onto the transfer body 2 to form an ink image. The post-ejection processing regions R3 and R4 are processing regions in which the ink image is processed after the ink is ejected. The post-ejection processing region R3 is a region where processing is performed by the peripheral unit 5B. The post-ejection processing region R4 is a region where processing is performed by the peripheral unit 5C. A transfer area R5 is an area where the ink image on the transfer body 2 is transferred to the recording medium P by the transfer unit 4. FIG. The post-transfer processing area R6 is an area where post-processing is performed on the transfer body 2 after transfer, and is an area where processing is performed by the peripheral unit 5D.

In the case of this embodiment, the ejection region R2 is a region having a certain section. The other regions R1, R3 to R6 are narrower than the ejection region R2. When compared to the dial of a clock, the pre-ejection treatment region R1 is approximately at the 10 o'clock position, the ejection region R2 is approximately in the range from 11 o'clock to 1 o'clock, and the post-ejection processing region R3 is approximately at the 2 o'clock position. , the post-ejection treatment region R4 is approximately at the 4 o'clock position. The transfer region R5 is approximately at the 6 o'clock position, and the post-transfer processing region R6 is approximately at the 8 o'clock position.

The transfer member 2 may be composed of a single layer, or may be a laminate of multiple layers. When composed of multiple layers, it may include, for example, three layers of a surface layer, an elastic layer, and a compression layer. The surface layer is the outermost layer having an imaging surface on which an ink image is formed. By providing the compression layer, the compression layer absorbs deformation and disperses local pressure fluctuations, so that transferability can be maintained even during high-speed recording. The elastic layer is the layer between the surface layer and the compression layer.

Various materials such as resins and ceramics can be appropriately used as the material of the surface layer, and materials having a high compressive elastic modulus can be used in terms of durability and the like. Specific examples include acrylic resins, acrylic silicone resins, fluorine-containing resins, condensates obtained by condensing hydrolyzable organosilicon compounds, and the like. The surface layer may be subjected to a surface treatment in order to improve the wettability of the reaction liquid, the transferability of the image, and the like. Examples of surface treatment include flame treatment, corona treatment, plasma treatment, polishing treatment, roughening treatment, active energy ray irradiation treatment, ozone treatment, surfactant treatment, and silane coupling treatment. A plurality of these may be combined. Also, the surface layer can be provided with an arbitrary surface shape.

Examples of materials for the compression layer include acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, silicone rubber, and the like. When molding such a rubber material, a predetermined amount of a vulcanizing agent, a vulcanization accelerator, etc. are blended, and a foaming agent, hollow fine particles, or a filler such as salt is blended as necessary to form a porous rubber material. may be As a result, the bubble portion is compressed with a change in volume in response to various pressure fluctuations, so deformation in directions other than the direction of compression is small, and more stable transferability and durability can be obtained. As porous rubber materials, there are continuous pore structures in which each pore is continuous with each other, and independent pore structures in which each pore is independent. You may

Various materials such as resins and ceramics can be appropriately used as the member of the elastic layer. Various elastomer materials and rubber materials can be used in terms of processability and the like. Specific examples include fluorosilicone rubber, phenylsilicone rubber, fluororubber, chloroprene rubber, urethane rubber, and nitrile rubber. Also included are ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, butadiene rubber, ethylene/propylene/butadiene copolymer, nitrile butadiene rubber and the like. In particular, silicone rubber, fluorosilicone rubber, and phenylsilicone rubber are advantageous in terms of dimensional stability and durability because of their low compression set. In addition, the change in elastic modulus due to temperature is small, which is advantageous in terms of transferability.

Various adhesives and double-sided tapes can be used between the surface layer and the elastic layer and between the elastic layer and the compression layer to fix them. Further, the transfer body 2 may include a reinforcing layer having a high compression elastic modulus in order to suppress lateral stretching when mounted on the transfer drum 41 and to maintain stiffness. Moreover, it is good also considering a woven fabric as a reinforcement layer. The transfer body 2 can be produced by arbitrarily combining each layer made of the above materials.

The impression cylinder 42 is pressed against the transfer body 2 at its outer peripheral surface. At least one grip mechanism for holding the leading edge of the recording medium P is provided on the outer peripheral surface of the impression cylinder 42 . A plurality of gripping mechanisms may be provided spaced apart in the circumferential direction of the impression cylinder 42 . The ink image on the transfer body 2 is transferred when the recording medium P passes through the nip portion between the impression cylinder 42 and the transfer body 2 while being conveyed in close contact with the outer peripheral surface of the impression cylinder 42 .

A driving source such as a motor for driving the transfer drum 41 and the impression cylinder 42 is common to them, and the driving force can be distributed by a transmission mechanism such as a gear mechanism.

<Peripheral unit>
The peripheral units 5A to 5D are arranged around the transfer drum 41. As shown in FIG. In this embodiment, the peripheral units 5A to 5D are, in order, an application unit, an absorption unit, a heating unit, and a cleaning unit.

The application unit 5A is a mechanism that applies a reaction liquid onto the transfer body 2 before the recording unit 3 ejects ink. The reaction liquid is a liquid containing a component that increases the viscosity of the ink. Here, increasing the viscosity of the ink means that the coloring materials, resins, etc. that make up the ink chemically react or physically adsorb when they come into contact with the components that increase the viscosity of the ink. An increase in ink viscosity is observed. This increase in the viscosity of the ink is not only when the viscosity of the ink as a whole increases, but also when the viscosity increases locally due to the aggregation of some of the components that make up the ink, such as colorants and resins. is also included.

The component that increases the viscosity of the ink is not particularly limited, and may be a metal ion, a polymer flocculant, or the like. However, a substance that causes a change in the pH of the ink and agglomerates the coloring material in the ink can be used. can be used. Examples of the mechanism for applying the reaction liquid include a roller, a recording head, a die coating device (die coater), and a blade coating device (blade coater). If the reaction liquid is applied to the transfer body 2 before the ink is ejected onto the transfer body 2, the ink that reaches the transfer body 2 can be immediately fixed. As a result, bleeding in which adjacent inks are mixed can be suppressed.

The absorption unit 5B is a mechanism for absorbing liquid components from the ink image on the transfer body 2 before transfer. By reducing the liquid component of the ink image, bleeding of the image recorded on the recording medium P can be suppressed. If the reduction of the liquid component is explained from a different point of view, it can be expressed as concentrating the ink forming the ink image on the transfer body 2 . Concentrating the ink means that the liquid component contained in the ink is reduced, thereby increasing the content ratio of the solid content such as the coloring material and resin contained in the ink to the liquid component.

Absorption unit 5B includes, for example, a liquid absorption member that contacts the ink image to reduce the amount of the liquid component of the ink image. The liquid absorbing member may be formed on the outer peripheral surface of the roller, or the liquid absorbing member may be formed in the form of an endless sheet and run cyclically. From the viewpoint of protecting the ink image, the moving speed of the liquid absorbing member may be the same as the peripheral speed of the transfer member 2 so that the liquid absorbing member is moved in synchronization with the transfer member 2 .

The liquid absorbing member may include a porous body that contacts the ink image. The pore diameter of the porous body on the surface that contacts the ink image may be 10 μm or less in order to suppress adhesion of ink solids to the liquid absorbing member. Here, the pore diameter means the average diameter, and can be measured by known means such as mercury porosimetry, nitrogen adsorption, SEM image observation, and the like. The liquid component is not particularly limited as long as it does not have a fixed shape, is fluid, and has a substantially constant volume. Examples of liquid components include water and organic solvents contained in inks and reaction liquids.

The heating unit 5C is a mechanism for heating the ink image on the transfer body 2 before transfer. By heating the ink image, the resin in the ink image is melted and the transferability to the recording medium P is improved. The heating temperature can be the minimum film-forming temperature (MFT) of the resin or higher. MFT can be measured by a generally known method, such as JIS K 6828-2:2003 or ISO2115:1996-compliant equipment. From the viewpoint of transferability and image fastness, the heating may be at a temperature higher than that of the MFT by 10° C. or more, and furthermore, at a temperature higher than that of the MFT by 20° C. or more. The heating unit 5C can use a known heating device such as various lamps such as infrared rays, a hot air fan, and the like. An infrared heater can be used in terms of heating efficiency.

The cleaning unit 5D is a mechanism for cleaning the transfer body 2 after transfer. The cleaning unit 5D removes ink remaining on the transfer body 2, dust on the transfer body 2, and the like. For the cleaning unit 5D, for example, a method of contacting the transfer body 2 with a porous member, a method of rubbing the surface of the transfer body 2 with a brush, a method of scraping the surface of the transfer body 2 with a blade, or the like can be appropriately used. can be done. Also, the cleaning member used for cleaning may have a known shape such as a roller shape or a web shape.

As described above, in this embodiment, the applying unit 5A, the absorbing unit 5B, the heating unit 5C, and the cleaning unit 5D are provided as peripheral units. , a cooling unit may be added. In this embodiment, the temperature of the transfer body 2 may rise due to the heat of the heating unit 5C. After the ink is ejected onto the transfer body 2 by the recording unit 3, if the ink image exceeds the boiling point of water, which is the main solvent of the ink, the ability of the absorption unit 5B to absorb the liquid component may deteriorate. By cooling the transfer body 2 so that the ejected ink is maintained below the boiling point of water, it is possible to maintain the ability to absorb liquid components.

The cooling unit may be a blowing mechanism that blows air to the transfer body 2 or a mechanism that brings a member (for example, a roller) into contact with the transfer body 2 and cools the member by air cooling or water cooling. Alternatively, it may be a mechanism for cooling the cleaning member of the cleaning unit 5D. The cooling timing may be a period after transfer and before application of the reaction liquid.

<Supply unit>
The supply unit 6 is a mechanism that supplies ink to each recording head 30 of the recording unit 3 . The supply unit 6 may be provided on the rear side of the recording system 1 . The supply unit 6 includes a storage section TK that stores ink for each type of ink. The storage section TK may be composed of a main tank and a sub-tank. Each reservoir TK and each recording head 30 communicate with each other through a channel 6a, and ink is supplied to the recording head 30 from the reservoir TK. The channel 6a may be a channel for circulating ink between the reservoir TK and the recording head 30, and the supply unit 6 may include a pump or the like for circulating ink. A degassing mechanism for degassing air bubbles in the ink may be provided in the middle of the flow path 6a or in the reservoir TK. A valve for adjusting the liquid pressure of the ink and the atmospheric pressure may be provided in the middle of the flow path 6a or in the reservoir TK. The height of the reservoir TK and the recording head 30 in the Z direction may be designed such that the ink surface in the reservoir TK is lower than the ink ejection surface of the recording head 30 .

<Conveyor>
The conveying device 1B is a device that feeds the recording medium P to the transfer unit 4 and discharges from the transfer unit 4 the recording material P' onto which the ink image has been transferred. The transport device 1B includes a feed unit 7, a plurality of transport cylinders 8, 8a, two sprockets 8b, a chain 8c and a recovery unit 8d. In FIG. 1, the arrows inside each component of the conveying device 1B indicate the rotation direction of the component, and the arrows outside indicate the conveying path of the recording medium P or the printed matter P'. The recording medium P is conveyed from the feeding unit 7 to the transfer unit 4, and the recorded matter P' is conveyed from the transfer unit 4 to the collection unit 8d. The side of the feeding unit 7 may be referred to as the upstream side in the transport direction, and the side of the collecting unit 8d may be referred to as the downstream side.

The feeding unit 7 includes a stacking section on which a plurality of recording media P are stacked, and also includes a feeding mechanism that feeds the recording media P one by one from the stacking section to the most upstream conveying cylinder 8 . Each transport cylinder 8, 8a is a rotating body that rotates around a rotation axis in the Y direction, and has a cylindrical outer peripheral surface. At least one gripping mechanism for holding the leading edge of the recording medium P (or the recorded matter P') is provided on the outer peripheral surface of each transport cylinder 8, 8a. Each gripping mechanism controls its gripping operation and release operation so that the recording medium P is transferred between adjacent transport cylinders.

The two transport cylinders 8a are transport cylinders for reversing the recording medium P. As shown in FIG. In the case of double-sided recording on the recording medium P, after transfer to the surface, the recording medium P is passed from the impression cylinder 42 to the transport cylinder 8a adjacent to the downstream side without being passed to the transport cylinder 8. FIG. The recording medium P is turned upside down via the two conveying cylinders 8a and transferred to the impression cylinder 42 again via the conveying cylinder 8 on the upstream side of the impression cylinder 42 . As a result, the back surface of the recording medium P faces the transfer drum 41, and the ink image is transferred to the back surface.

Chain 8c is wound between two sprockets 8b. One of the two sprockets 8b is a driving sprocket and the other is a driven sprocket. The rotation of the drive sprocket causes the chain 8c to circulate. The chain 8c is provided with a plurality of gripping mechanisms spaced apart in its longitudinal direction. The gripping mechanism grips the edge of the recorded material P'. The recorded material P′ is transferred from the conveying cylinder 8 located at the downstream end to the gripping mechanism of the chain 8c, and the recorded material P′ gripped by the gripping mechanism is transported to the collection unit 8d by the traveling of the chain 8c, and the gripping is released. be. As a result, the recorded matter P' is loaded in the collection unit 8d.

<Post-processing unit>
Post-processing units 10A and 10B are provided in the transport device 1B. The post-processing units 10A and 10B are arranged downstream of the transfer unit 4 and are mechanisms for performing post-processing on the printed material P'. The post-processing unit 10A performs processing on the front side of the recorded matter P', and the post-processing unit 10B performs processing on the back side of the recorded matter P'. As the content of the processing, for example, the image recording surface of the recorded matter P' may be coated for the purpose of protecting the image, glossing the image, or the like. Examples of coating include application of liquid, welding of sheets, lamination, and the like.

<Inspection unit>
The transport device 1B is provided with inspection units 9A and 9B. The inspection units 9A and 9B are arranged downstream of the transfer unit 4 and function as detection means in this embodiment, which is a mechanism for inspecting the printed matter P'.

In the case of this embodiment, the inspection unit 9A is a photographing device for photographing an image recorded on the recorded material P', and includes an imaging device such as a CCD sensor or a CMOS sensor, for example. The inspection unit 9A captures recorded images during the continuous recording operation. Based on the image photographed by the inspection unit 9A, it is possible to check the time-dependent change of the color tone of the recorded image and determine whether the image data or the recorded data can be corrected. In the case of this embodiment, the inspection unit 9A has an imaging range set on the outer peripheral surface of the impression cylinder 42, and is arranged so as to be able to partially photograph a recorded image immediately after transfer. All recorded images may be inspected by the inspection unit 9A, or may be inspected every predetermined number.

In the case of this embodiment, the inspection unit 9B is also a photographing device for photographing an image recorded on the recorded material P', and includes, for example, an imaging device such as a CCD sensor or a CMOS sensor. The inspection unit 9B takes a recorded image in the test recording operation. The inspection unit 9B captures the entire recorded image, and based on the image captured by the inspection unit 9B, can perform basic settings for various corrections related to the recorded data. In the case of this embodiment, it is arranged at a position for photographing the printed matter P' conveyed by the chain 8c. When the inspection unit 9B captures a recorded image, the running of the chain 8c is temporarily stopped and the whole is captured. The inspection unit 9B may be a scanner that scans the printed material P'.

<Hardware configuration of control system>
Next, the configuration of the control system of the recording system 1 will be described. FIG. 5 is a block diagram showing the overall configuration of the control system of the recording system 1. As shown in FIG. A control system of the recording system 1 includes a host device HC2 and a control unit 13. FIG. The control unit 13 is communicatively connected to the host device HC2, and the host device HC2 is communicatively connected to the host device HC1. In this embodiment, the host device HC2 functions as control means for performing imposition processing and the like, which will be described later. Further, the control unit 13 functions as a control means for comprehensively controlling the entire recording apparatus including the ejection operation of the recording head 30 and the like.

In the host device HC1 shown in FIG. 5, document data that is the basis of a recorded image is generated or stored. The manuscript data here is generated, for example, in the form of an electronic file such as a document file or an image file. This manuscript data is transmitted to the host device HC2. The host device HC2 converts the received document data into a data format that can be used by the control unit 13 (for example, RGB data expressing an image in RGB). This process is called rendering. The image data processed by the host device HC2 is transmitted to the control unit 13, and the control unit 13 starts a recording operation based on the received image data. In this embodiment, each pixel in the horizontal direction of the image data corresponds to each nozzle in the nozzle array, and one pixel in the horizontal direction of the image data is printed by one of the nozzle arrays i to p in FIG.

Here, the configurations of the host device HC2 and the control unit 13 will be described. The host device HC2 is composed of a DFE device (Digital Front End) that performs rendering processing and imposition processing, which will be described later. The host device HC2 has a processing unit 201, a ROM 202, a RAM 203, an HDD 204, an external I/F 205, a display unit 206, and an operation unit 207, which are connected via a system bus 208, respectively. In this embodiment, the processing unit 201 is a processor such as a CPU (Central Processing Unit). A central processing unit in the form of a microprocessor (microcomputer). The CPU 201 controls the overall operation of the high-level device HC2 by executing programs and activating hardware. A ROM (Read Only Memory) 202 stores programs to be executed by the CPU 201 and fixed data necessary for various operations of the host device HC2. A RAM (Random Access Memory) 203 is used as a work area for the CPU 201 and as a temporary storage area for various received data. The RAM 203 also stores various setting data, a management table for image generation jobs, and working data. A HDD (Hard Disk Drive) 204 stores an image generation job input from an external device. In addition, the HDD 204 is capable of storing and reading programs to be executed by the CPU 201 and setting information required for various operations of the higher-level device HC2 in the built-in hard disk. It should be noted that another large-capacity storage device may be used instead of the HDD 404 . Alternatively, an external storage device may be used. In this embodiment, the CPU 201 expands a program stored in the ROM 202 into the RAM 203, and executes processing described below according to the program. However, the host device HC2 may further include an auxiliary storage device and a GPU (Graphics Processing Unit), and it is also possible to execute the processing in this embodiment by performing calculations with the CPU and/or the GPU. is.

The host device HC2 configured as described above performs imposition processing for imposing each document data transmitted from the host device HC1. The imposition process is a process of arranging manuscript data transmitted from the host apparatus HC1 on each page in consideration of processes such as recording, cutting, and bookbinding.

FIG. 6 shows a recording surface 901 (recorded material P′) on which image data imposition processed by the host device HC2 and nozzle check patterns 906 to 909 arranged by the control unit 13 are recorded on one recording medium P. Give an example. In the figure, 902 to 905 are images obtained by expanding the image file transmitted from the host device HC1, and in this example, they are cut in the post-recording process, and each sheet is a one-page product. In addition, nozzle check patterns 906 to 909 for checking the discharge state of the nozzles are also recorded on the recording surface 901 . Nozzle check patterns 906 to 909 are used to check ejection failures of nozzles during printing, and are arranged and printed at predetermined positions so that correspondence between the image and the nozzle row positions can be obtained. The host device HC2 impositions the image data so that the images 902I to 905I are arranged as shown in FIG. 6, and transfers the image data to the control unit . Furthermore, after that, the control unit 13 arranges the nozzle check patterns 906 to 909 at the positions shown in the figure.

Note that in a transfer-type recording apparatus such as that of the present embodiment, the recording result is recorded by vertically or horizontally reversing the image data. For this reason, the image data is actually inverted for each nozzle position of the recording head 30. However, in order to facilitate the explanation, in FIG. The image is shown in such an arrangement.

Also, the host device HC2 issues an image data ID. The image data ID is a unique number for each image data recorded on the recorded matter P'. This number is sent to the control unit 13 at the same time as the image data.

The host device HC2 creates information required in the post-process and notifies it to the post-process 140. FIG. The post-process 140 includes a cutting machine 141 and the like for cutting the recorded matter P'. The cutting machine 141 cuts the images 902I to 905I included in the recorded matter P′ recorded by the recording apparatus 1A into a one-page product, based on the information transmitted from the higher-level device HC2. cutting. The information transmitted from the host device HC2 to the post-process 140 includes, for example, the image data ID, the number of image forming areas, and the position of the image forming area (X [mm], Y [mm]) with the upper left corner of the printed matter P′ as the origin. , and size (width [mm], height [mm]) are file information described in XML format. In FIG. 6, the image forming area means a rectangular area occupied by each of the images 902I to 905I to be formed on the recording medium P, and an image (ink image) 902Ia formed by applying ink. It refers to the region encompassing ~905Ia. In other words, the image forming area means an area corresponding to image data composed of print data instructing ejection of ink droplets and non-printing data indicating non-ejection of ink droplets, and is an area in which an ink image can be formed by the image data. point to

The above XML file information may be transmitted to the cutting machine 141 provided in the post-process 140 via the LAN. Also, the file information in XML format may be sent to the control unit 13 at the same time as the image data, and the file information in XML format may be sent from the control unit 13 to the cutting machine 141 . Alternatively, the above information may be entered in a two-dimensional code such as a bar code or QR code (registered trademark) and recorded in the blank area of the recording medium P. FIG. That is, it is also possible to read the code recorded on the recording medium P in the post-process or the inspection unit 9A, and to have the post-process 140 acquire the information. It should be noted that the post-process 140 is not limited to the cutting machine 141, and it is also possible to adopt a configuration that includes a device for performing a coating process such as the post-processing units 10A and 10B.

By transmitting the information created by the host device HC2 to the cutting machine 141 in this manner, the cutting machine 141 can recognize which position of the printed material P' should be cut, and cut the printed material properly. It can be performed. Further, by providing the above information to the coating apparatus, it becomes possible to avoid coating unnecessary portions cut from the product, and wasteful coating can be reduced. Imposition and image data ID issuance are not limited to the host device HC2, and may be performed by the host device HC1. In that case, it is converted to a predetermined file format such as PDF and transmitted to the HC2.

The control unit 13 of this embodiment shown in FIG. 5 is roughly divided into a main controller 13A and an engine controller 13B. Main controller 13A includes processing unit 131 , storage unit 132 , operation unit 133 , image processing unit 134 , communication I/F (interface) 135 , buffer 136 and communication I/F 137 .

The processing unit 131 is a processor such as a CPU, executes programs stored in the storage unit 132, and controls the entire main controller 13A. The processing unit 131 is hereinafter referred to as a CPU 131 . The storage unit 132 is a storage device such as a RAM, a ROM, a hard disk, or an SSD, stores programs executed by the CPU 131 and data, and provides the CPU 131 with a work area. The operation unit 133 is a touch panel and receives user instructions. The touch panel also has a display function, and also has the role of notifying the user of device errors, defects in recorded materials, and the like. The operation unit 133 may also include input devices such as a keyboard and a mouse.

The image processing unit 134 is, for example, an electronic circuit or CPU having an image processor. The buffer 136 is, for example, RAM, hard disk or SSD. A communication I/F 135 communicates with the host device HC2, and a communication I/F 137 communicates with the engine controller 13B. Broken arrows in FIG. 4 illustrate the flow of image data processing. Image data received from the host device HC2 via the communication IF 135 is accumulated in the buffer 136. FIG. The image processing unit 134 reads the image data from the buffer 136 , performs predetermined image processing on the read image data, and stores the processed image data in the buffer 136 again. The image data after image processing stored in the buffer 136 is transmitted from the communication I/F 137 to the engine controller 13B as print data used by the print engine.

Here, part of the image processing executed in this embodiment will be described. FIG. 7 is a flow chart showing the procedure of image processing according to this embodiment. It should be noted that S attached to each process number in the flow charts referred to in this specification, including FIG. 7, means step. 7 are performed by the image processing unit 134 shown in FIG. 5, and the processing of S707 is performed by the later-described recording control unit 15A shown in FIG. However, these processes can also be performed at other locations such as the host device HC2.

In S701, mapping processing is performed. Here, an Output ICC Profile created in advance for each printing apparatus 1A, type of printing paper, and type of ink used is used. In this example, the host device HC2 uses the Output ICC Profile to convert the document data into device-dependent RGB (dRGB) by a known method. dRGB is sent to the main controller 13A as 16-bit image data for each channel.

In S702, color shading is performed. Color shading corrects the color difference between the ejection substrates (301 and 302, etc.) by a known method using a pre-created three-dimensional LUT (Lookup Table). For correction, regions are divided in units of the width of the overlapping portion of the ejection substrate and the ejection substrate, or in units of widths smaller than that, and a three-dimensional LUT is provided for each region. Here, image data dRGB is input, and dRGB' after correction is created. Note that dRGB' is 16-bit image data for each channel.

In S703, ink color separation processing is performed. In this embodiment, dRGB' is converted into device-dependent CMYK (dCMYK) by a pre-prepared LUT. Note that here, color separation processing is performed according to the four colors of C, M, Y, and K, but the color separation processing creates data according to the ink colors used in the printing apparatus. For example, in addition to C, M, Y, and K, inks such as lC (light cyan), lM (light magenta), Gy (gray), R (red), G (green), and B (blue) can be used by a printing apparatus. If used, create data corresponding to those ink colors. dCMYK is 16-bit image data for each channel. In addition to dCMYK, the present embodiment also generates transfer liquid data.

In S704, gamma correction processing is performed. In this embodiment, a one-dimensional LUT corresponding to each of C, M, Y, and K colors is prepared in advance. Using this one-dimensional LUT, the difference between the increase/decrease in the amount of ink applied to the recording medium P and the human visual characteristics is absorbed, and conversion processing is performed so that the increase/decrease in the dCMYK signal values matches the human visual characteristics. . In this gamma correction process, dCMYK is input and dCMYK' is output. dCMYK' is 16-bit image data for each channel.

In S705, head shading is performed. Head shading corrects the color difference between the ejection substrates (301 and 302, etc.) by a known method using a one-dimensional LUT created in advance. Here, since correction is performed for each ink color (C, M, Y, K), the number of ink colors (4 if there are four colors of C, M, Y, K) A number of one-dimensional LUTs multiplied by . In head shading, dCMYK' is input and dCMYK'' is output. dCMYK'' is 16-bit image data for each channel. If unevenness occurs in the transfer, shading of the transfer liquid may be performed in S705. As a result, transfer can be performed with a smaller amount of transfer liquid than if the amount of transfer liquid on the one surface of the recording paper is uniformly increased in accordance with portions where transfer is insufficient, and the amount of transfer liquid used can be suppressed.

In S706, halftone processing is performed. In halftone processing, a halftone image dCMYK''' is created by comparing each pixel data of dCMYK'' with a threshold value of a dither matrix. In this embodiment, multi-value halftone processing is performed using a known technique. dCMYK''' is 16-bit image data for each channel, and each pixel value corresponds to the number of ejected inks. The above S702 to S706 are performed by the image processing unit .

Next, in S707, binarization processing is performed. This processing is performed by a recording control section 15A in an engine controller 13B, which will be described later. Each pixel of the multi-valued image data dCMYK''' is divided into two values of ejection (ON: pixel value 1) and no ejection (OFF: pixel value 0) for each nozzle. Here, an example of binarization processing will be described.

As described above, in the print head 30 shown in FIG. 3, the ejection substrates 301 and 302 have overlapping portions and non-overlapping portions in the Y direction. There are four nozzles in each nozzle column i-l in the overlapping portion and two nozzles in each nozzle column m-p in the non-overlapping portion.

In the recording head 30 having nozzles arranged in this manner, ejection is performed as follows according to each pixel value (0 to 2) of dCMYK''' corresponding to the number of ink shots.

First, ejection from each of the two nozzles in each of columns m to p (hereinafter referred to as No. 0 nozzle and No. 1 nozzle) present in a portion where adjacent ejection substrates do not overlap will be described.
・When the pixel value is 0, neither the No. 0 nozzle nor the No. 1 nozzle ejects ink.
- When the pixel value is 1, one of No. 0 nozzle and No. 1 nozzle is selected by a predetermined method, and ink is ejected only from the one nozzle.
・When the pixel value is 2, ink is ejected from both the No. 0 nozzle and the No. 1 nozzle.

Next, ejection from the four nozzles in columns i to l (referred to as No. 0 nozzle to No. 3 nozzle) present in a portion where adjacent ejection substrates overlap will be described.

・When the pixel value is 0, ejection is not performed from any of No. 0 to No. 3 nozzles.

- When the pixel value is 1, one nozzle is selected from No. 0 to No. 3 nozzles by a predetermined method, and ink is ejected from only this one nozzle.

- When the pixel value is 2, two of the four nozzles are selected by a predetermined method, and ink is ejected only from the selected two nozzles.

Here, the predetermined method is, for example, No. 0→No. 1→No. 2→No. 3→No. 1 . . . , and the nozzles for ejection are selected according to the order. Another method for selecting nozzles is to select the nozzles to be ejected according to the X-coordinate of the image, or to randomly assign the dots to be formed to the nozzles so that all nozzles probabilistically have approximately the same number of ejections. method.

Further, if there is an individual difference in the amount of ejection between the adjacent ejection substrates, for example, the ejection substrate 301 and the ejection substrate 302, the recorded image may have a density difference. For example, a density difference occurs between an image printed only with the ejection substrate 301, an image printed with the overlapping portion of the ejection substrates 301 and 302, and an image printed with the ejection substrate 302 only. Image borders may be noticeable. In this case, the rate at which ink is ejected from each nozzle of the ejection substrate 301 and the ejection substrate 302 may be changed for each column of nozzles. For example, they are distributed to each nozzle so that the following ratios are probabilistically obtained.

As described above, there is an effect that the density difference between chips is switched step by step, and the boundary becomes inconspicuous.

After finishing the processing of S607, the processing shown in the flowchart of FIG. 7 ends. In this manner, the image data is converted into an instruction (printing data) instructing ejection or non-ejection.

FIG. 8 is a block diagram showing the configuration of the engine controller 13B shown in FIG. 4. As shown in FIG. The engine controller 13B includes a plurality of control units (14, 15A to 15E), acquires detection results of the sensor group and the actuator group 16 provided in the recording system 1, and performs drive control. Each of these control units includes a processor such as a CPU, storage devices such as RAM and ROM, and interfaces with external devices. Note that the division of the control units is an example, and a part of the control may be executed by a plurality of subdivided control units. It may be configured to be performed by one control unit.

The engine control unit 14 controls the entire engine controller 13B. The recording control unit 15A converts the image data received from the main controller 13A into data (recording data) in a data format suitable for driving the recording head 30, such as raster data. The recording control section 15</b>A controls ejection of each recording head 30 .

The transfer control section 15B controls the application unit 5A, the absorption unit 5B, the heating unit 5C, and the cleaning unit 5D.

The reliability control section 15C controls the supply unit 6, the recovery unit 12, and the drive mechanism that moves the recording unit 3 between the ejection position POS1 and the recovery position POS3.

The transport control section 15D controls the driving of the transfer unit 4 and the transport device 1B. The inspection control section 15E controls the inspection unit 9B and the inspection unit 9A.

Among the sensor group and the actuator group 16, the sensor group includes a sensor for detecting the position and speed of the movable portion, a sensor for detecting temperature, an imaging device, and the like. The actuator group includes motors, electromagnetic solenoids, electromagnetic valves, and the like.

<Operation example>
FIG. 9 is a diagram schematically showing an example of the recording operation. The following steps are cyclically performed while the transfer drum 41 and impression cylinder 42 are rotated. As shown in state ST1, first, the reaction liquid L is applied onto the transfer member 2 from the application unit 5A. The portion of the transfer body 2 to which the reaction liquid L is applied moves as the transfer drum 41 rotates. When the portion to which the reaction liquid L is applied reaches below the recording head 30, ink is ejected from the recording head 30 onto the transfer body 2 as shown in state ST2. An ink image IM is thus formed. At this time, the ejected ink mixes with the reaction liquid L on the transfer body 2, thereby promoting aggregation of the coloring material. The ejected ink is supplied to the recording head 30 from the reservoir TK of the supply unit 6 .

The ink image IM on the transfer body 2 moves as the transfer body 2 rotates. When the ink image IM reaches the absorbing unit 5B, the liquid component is absorbed from the ink image IM by the absorbing unit 5B as shown in state ST3. When the ink image IM reaches the heating unit 5C, the ink image IM is heated by the heating unit 5C as shown in state ST4, the resin in the ink image IM is melted, and the ink image IM is formed. In synchronism with the formation of the ink image IM, the recording medium P is transported by the transport device 1B.

As shown in state ST5, the ink image IM and the recording medium P reach the nip portion between the transfer body 2 and the impression cylinder 42, the ink image IM is transferred to the recording medium P, and the recorded matter P' is manufactured. . After passing through the nip portion, the image recorded on the recorded material P' is photographed by the inspection unit 9A, and the recorded image is inspected. The recorded matter P' is conveyed to the collecting unit 8d by the conveying device 1B.

The portion of the transfer member 2 on which the ink image IM was formed is cleaned by the cleaning unit 5D when it reaches the cleaning unit 5D as shown in state ST6. After the cleaning, the transfer body 2 rotates once, and the transfer of the ink image to the recording medium P is repeated in the same procedure. In the above description, for ease of understanding, one rotation of the transfer body 2 is used to transfer the ink image IM onto one recording medium P once. Transfer of the ink image IM onto a plurality of recording media P can be performed continuously.

Continuing such a recording operation requires maintenance of each recording head 30 . FIG. 10 shows an operation example during maintenance of each recording head 30 . A state ST11 indicates a state in which the recording unit 3 is positioned at the ejection position POS1. State ST12 indicates a state in which the recording unit 3 is passing through the preliminary recovery position POS2, and the recovery unit 12 executes the process of recovering the ejection performance of each recording head 30 of the recording unit 3 during passage. Thereafter, as shown in state ST13, the recovery unit 12 performs a process of recovering the ejection performance of each print head 30 while the print unit 3 is positioned at the recovery position POS3.

<Recorded image example>
11 and 12 are diagrams showing an example of the printhead 30 used in the printing apparatus 1A of the present embodiment and a printed matter printed by the printhead. FIG. 11(a) shows an image printed by normally ejecting ink from all the nozzles provided in each ejection substrate 310 of the print head 30 without ejection failure. FIG. 11B is a diagram showing an example of an image formed when an ejection failure of the print head 30 occurs. 12A and 12B are diagrams for explaining the re-imposition processing performed based on the image shown in FIG. 11B, and FIG. FIG. 12(b) is a diagram showing an image formed after the reimposition processing is performed.

In FIGS. 11 and 12, P' denotes a recorded matter after an image is recorded on one sheet of recording medium P. In FIG. Each of the images 902I to 905I represents an image of one page recorded on the recording medium P (hereinafter referred to as a page image). The images 902I to 905I for one page are cut by the cutting machine 141 in a post-process, and each of them becomes one sheet of output. Also, as described above, the area where the images 902I to 905I are formed is called an image forming area. If there are printer's marks (not shown) or two-dimensional codes (not shown) that are required in a post-process, the area in which the images are formed is also defined as the image forming area.

In the lower portion of the print medium P, nozzle check patterns 906 to 909 are printed for checking the ejection state of the nozzles, as in FIG. Among them, 906 is a nozzle check pattern printed by a nozzle array that ejects cyan ink. Similarly, 907 is a nozzle check pattern printed by a nozzle row that ejects magenta ink, 908 is a nozzle row that ejects yellow ink, and 909 is a nozzle row that ejects black ink. By reading each nozzle check pattern with the inspection unit 9A (FIG. 1), it is possible to check whether or not each nozzle row is ejecting ink normally. Each nozzle check pattern is printed with a single color ink. Further, by performing the printing operation of the nozzle check patterns 906 to 909, it becomes possible to keep the ink in each nozzle in a state suitable for ejection. That is, by performing the printing operation of the nozzle check patterns 906 to 909, it is possible to suppress the drying and thickening of the ink, and to discharge the ink containing air bubbles and dust to the outside of the nozzles so that the ink is fresh. It can be replaced with ink. In other words, the printing operation of the nozzle check pattern plays the same role as the preliminary ejection for maintaining and recovering the ejection performance of the nozzles. Therefore, it is possible to maintain proper ejection performance even for nozzles that are used infrequently in the image forming area.

Preliminary ejection may be performed not only on the recording medium P but also on other portions. For example, it is possible to periodically eject ink to the recovery unit 12 shown in FIG. 4 or to a preliminary ejection groove (not shown) dedicated to preliminary ejection, and the same effect can be obtained. A sponge or the like for absorbing ink may be provided in the preliminary ejection groove, or the ejected ink may be sucked by a pump.

<Flowchart>
Here, the overall processing procedure executed in this embodiment will be described according to the flowchart of FIG. 13 .

In S1301, based on the document data transmitted from the host apparatus HC1, the host apparatus HC2 performs imposition processing and rendering processing to generate image data for printing an image as shown in FIG. 11A, for example. do. However, at this stage, the nozzle check patterns 906 to 909 are not included in the image. This image data generation processing is performed by the CPU 201, which is a processing unit. The generated image data is stored in the RAM 403 and transmitted to the main controller 13A of the printing apparatus 1A via the external I/F 205. FIG. It should be noted that the imposition processing performed at the stage of S1301 is the imposition processing that is performed before detection of an ejection failure of a nozzle, which will be described later, and this imposition processing is hereinafter referred to as initial imposition processing. Further, imposition processing that is performed based on the detection result after ejection failure of a nozzle is detected is referred to as re-imposition processing.

In S1302, the main controller 13A of the printing apparatus 1A receives the image data transmitted from the host device HC2 via the I/F 135 and temporarily stores it in the RAM 203. FIG. After that, the image data stored in the RAM 203 is subjected to the image processing described above in the image processing unit 134 . Then, a process of adding nozzle check patterns 906 to 909 to the processed image data (print data) is performed, and the generated print data is sent to the engine controller 13B. The engine controller 13B drives the nozzles of the recording head 30 based on the received recording data, records an image on the recording medium P, and obtains a recorded matter P'. In S1303, the inspection unit 9A shown in FIG. 1 optically reads the printed material P' to obtain read image data.

In S1304, non-ejection nozzles are detected by inspecting locations corresponding to the nozzle check patterns 906 to 909 shown in FIG. 9 in the read image data acquired in S1303. Specifically, based on the pixel values of the nozzle check patterns 906 to 909 on the image data, the pixel value of each pixel obtained from the read image data or the average value of the pixel values of one block composed of a plurality of pixels is determined in advance. by checking whether it is within the range of values specified.

For example, let Rs, Gs, and Bs be the R, G, and B values of the pixels in the read image data, and let R, G, and Bs be the predetermined ideal R, G, and B values, that is, the values of the pixels formed by nozzles in which no ejection failure occurs. When Rref, Gref, and Bref are used, the color difference ΔRGB is obtained by the following equation (1).

Thereafter, the color difference ΔRGB obtained by Equation 1 is compared with a predetermined allowable range value Th, and if the color difference ΔRGB is large, it is determined that the nozzle has an ejection failure. Note that the color difference may be obtained by converting the RGB values of the pixels of the image data into CIELab or YCC values using a known method.

Further, in the above example, the occurrence of ejection failure of the nozzle is determined based on the color difference, but it may be determined based on optical characteristics other than the color difference. In the case of general colored ink, if a nozzle has an ejection failure, the location corresponding to the nozzle with the ejection failure (ejection failure nozzle) will have a value close to the color (white) of the print medium, so the luminance rises. Therefore, it is also possible to determine whether or not the nozzle has an ejection failure based on how much the brightness has increased from the ideal value. In addition, ejection failure may be determined based on optical characteristics other than brightness, such as saturation.

In the present embodiment, the main controller 13A performs the process of detecting defective ejection nozzles. However, a processing device such as a computer (not shown) is provided separately from the main controller 13A. may be performed. According to this, the processing for printing and the processing for judging defective ejection nozzles can be performed separately, and there is an advantage that the load is distributed.

It is also possible to detect ejection failure without using image data. For example, in a print head that employs a thermal ink jet method, a phenomenon occurs in which the temperature rises when an ejection failure occurs. It is also possible to detect an ejection failure by utilizing this phenomenon. Specifically, it is possible to provide the recording head 30 with a temperature sensing function, and to detect the occurrence of an ejection failure depending on whether the detected temperature is equal to or higher than a predetermined value.

Japanese Patent Laid-Open No. 2009-101576, for example, discloses a technique that enables ejection failure detection based on the temperature of the print head. The recording head disclosed in the publication is provided with a temperature detecting element formed of a thin film resistor via an insulating film directly below the electrothermal conversion element provided for each nozzle. In this recording head, a driving pulse is selectively applied to a plurality of electrothermal transducers, and temperature information of the driven electrothermal transducers is obtained from the temperature detection element, thereby performing ejection failure detection with high accuracy. It is possible.

If such a non-ejection detection method is used, it is possible to skip the process of reading the printed matter P' in S1303. Furthermore, according to this method, the position of the nozzle where the ejection failure occurs can be grasped, so that the process of specifying the ejection failure nozzle in S1305, which will be described later, can be skipped. Further, even if the existence of a nozzle with ejection failure is known before printing, S1301 to S1304 and S1305 can be skipped and the process can be started from S1306. According to this, it becomes possible to advance the processing at high speed.

FIG. 11(a) shows a printed matter P′ in which an image is normally printed without an ejection failure in the nozzles, whereas FIG. 11(b) shows a printed matter P′. A printed matter P′ is shown when an ejection failure occurs in a magenta ink nozzle at a position a in the head 30 . In FIG. 11, when the horizontal direction is the Y direction and the vertical direction is the X direction, the nozzles are arranged in the Y direction and the recording medium P is conveyed in the X direction. In the example of the printed matter P' shown in FIG. 11B, magenta ink is not ejected over the entire line in the vertical direction (X direction) of the printing medium P at the position a on the Y coordinate due to ejection failure of the nozzle. Therefore, in 903, 905, and 907, color dropout occurs at the position a on the Y coordinate. On the other hand, as in the nozzle check patterns 906, 908, and 909, printing is performed with an appropriate color for locations where magenta ink is not used.

To simplify the explanation, this example shows the case where one nozzle row fails to discharge, but the brightness is high (the density is low) even when a problem occurs in one nozzle in the nozzle row. Therefore, it is possible to detect an ejection failure by using Equation 1 for obtaining ΔRGB. In the example shown in FIG. 11B, it is detected by the process of S1304 that the nozzle corresponding to the Y-coordinate position a has an ejection failure in the nozzle array of the print head 30 that ejects magenta ink. can do.

If it is determined to continue the printing operation in the processing of S1308, which will be described later, and there is a known defective area, the ejection failure nozzle detection process is not performed for the nozzle array in the known defective area. Alternatively, even if an ejection failure nozzle is detected, the detection result is ignored. As a result, in the process of judging the overlapping of the defective area and the image formation area, which will be described later with reference to FIG. 12, the known defective area is excluded from the target of processing, so that unnecessary processing is not performed. .

Further, in S1304, detection other than detection of ejection failure may be performed. For example, the image data after rendering or image data obtained by processing the rendered image data is compared with the read image data, and it is determined whether or not there is any defect in the recorded matter. The processed image data is, for example, image data after color separation, image data obtained by simulating color change in a recording process or an imaging process from image data, and the like. In addition, defects in the recorded matter include scratches on the recorded matter caused by poor transfer. If a problem occurs, the recording operation is stopped, and processing such as issuing a warning is performed. Note that if step S1308 has already passed and it has been determined to continue the printing operation, the defective area is outside the image forming area, so the image forming area is not affected even if the defective area is not inspected. Therefore, in this inspection as well, the known defective area is not inspected, or even if a defect is detected, it is ignored. As a result, the recording operation can be continued without uselessly stopping the recording operation.

If no ejection failure of the nozzle is detected in S1304, the process proceeds to S1309, and in the post-process 140, a predetermined process (cutting of the printed material P' by the cutting machine 141) is performed as usual. If ejection failure of the nozzle is detected, the process proceeds to S1305.

In S1305, the main controller 13A identifies the ejection failure nozzle. A marker 913 shown in FIG. 11 is used to identify the ejection failure nozzle. Markers 913 are recorded at regular intervals and used to identify the positional relationship between the nozzle positions and the image positions.

Based on the original image data corresponding to the area of the recording surface of the recording medium, an ejection/non-ejection command (printing data) is created for the nozzles at the same Y-coordinate position. It is predetermined in which nozzle column a pixel is printed. Note that, in this example, the marker 913 is a triangle, and one vertex of the triangle is the position of a predetermined column of nozzles. Note that the marker is not limited to a triangular shape, and other shapes such as a line or spiral pattern may be used as long as the pixel position can be determined by reading the marker.

It is determined whether the position of a on the Y coordinate detected in S1304 (see FIG. 11B) is located between what marker and what marker. In the example of FIG. 11B, it is determined that there is an ejection failure between the sixth and seventh markers from the left.

Next, the pixel positions of the 6th and 7th markers from the left on the image data shown in FIG. , the location of the nozzle column in question is calculated. It should be noted that a defective nozzle column means a nozzle column that includes an ejection failure nozzle.

For this calculation, for example, Equation 2 below may be used.
Ym6: Pixel position (Y coordinate) of the 6th marker.
Ym7: Pixel position (Y coordinate) of the 7th marker.
YE: Pixel position (Y coordinate) determined to have a defect.
N6: Nozzle position corresponding to the 6th marker N7: Nozzle position corresponding to the 7th marker NE: Position of the defective nozzle row

A column of nozzles having an ejection failure is identified from the NE calculated by Equation 2 above. As shown in FIG. 3, the nozzle rows are arranged at regular intervals and can be easily identified. For example, a table in which the positions of individual nozzle columns are recorded in advance may be used, and the nozzles whose calculated nozzle positions NE are closest to the positions of the nozzle columns in the table may be determined as the ejection failure nozzles.

Here, an example of another method for identifying a defective ejection nozzle will be described with reference to FIG. 1101 in FIG. 3 shows an example of another nozzle check pattern printed on the printing medium P. FIG. Each nozzle ejects ink once to form each dot indicated by 1002 . This pattern is read in S1304 to detect whether or not each dot 1002 exists at a predetermined location. If there are no dots at the predetermined location and at other locations, it can be determined that the nozzle has failed to eject. Also, if the dot exists in a location different from the predetermined location, it can be determined that there is an abnormality (distortion) in the ink ejection direction of the nozzle. Since each dot 1002 is associated with a nozzle on a one-to-one basis, it is possible to determine which nozzle is abnormal based on the nozzle check pattern shown in FIG. 3B.

In the present embodiment, the main controller 13A performs the process of identifying defective ejection nozzles. you can go According to this, it is possible to perform the processing for printing and the processing for specifying the ejection failure nozzle in a distributed manner, thereby distributing the load.

After performing the above process of specifying the ejection failure nozzle, the main controller 13A performs the process of specifying the defective area in S1306. In other words, it functions as a defective area identifying means. It should be noted that this defective area specifying process can also be performed by a processing device such as a computer (not shown) provided separately from the main controller 13A.

In S1306, all the columns located at the Y coordinate of the nozzle row including the ejection failure nozzle obtained in S1305 described above are determined to be defective regions. This is because, in this embodiment, the recording paper P is conveyed in the X direction, and the same Y coordinate position is recorded by the same column of nozzles. In addition, in this embodiment, the defective area is expanded in the front-rear direction of the Y-coordinate of the nozzle column including the ejection failure nozzle, that is, in the horizontal direction (Y-direction). This is because the accuracy with which the ejection failure nozzles are specified varies depending on the reading resolution and the like when the printed matter P' is read in S1303. For example, the accuracy of specifying the ejection failure nozzle depends on the recording speed (the speed at which the recording medium P passes through the inspection unit 9A), the transportation accuracy of the recording medium, the illumination, and the reading method of the inspection unit 9A (line sensor, area sensor, scanner). etc. Furthermore, the accuracy of identifying the ejection failure nozzle changes depending on the types of markers, the recording resolution, the resolution of the sensor, and the like. Therefore, the accuracy for reading and identifying the ejection failure nozzle is obtained in advance, and the area having a width including the ejection failure nozzle is determined as the defective area.

It should be noted that, as long as the device is capable of specifying the ejection region with high accuracy, one column of nozzles including nozzles in which ejection failure has occurred may be set as the defective region. As shown in FIG. 12B, the narrower the width of the identifiable defective area, the easier the reimposition process (the process in FIG. 13) for setting the image forming area at a position avoiding the defective area. This re-imposition processing will be described in detail later.

FIGS. 12A and 12B show examples of defective areas. A region 920 surrounded by a broken line in FIG. 12 indicates a defective region. A defective area 920 exemplified in FIG. 12A is a vertical pixel row at the position a on the Y coordinate where color loss occurs in the magenta nozzle check pattern 907, and is positioned before and after the pixel row in the Y direction. It is an area corresponding to the vertical pixel column.

After determining the defective area 920, the control unit 13 transmits at least the image ID and information indicating the location of the defective area to the host device HC2. This information is transmitted in a predetermined format over the LAN. The format of the information to be transmitted is, for example, an image ID in the first 64 bits, and then a binary file in which the X coordinate, Y coordinate, width [pixel], and height [pixel] of the defective area 920 are each stored in a 32-bit integer type. etc. If there are a plurality of defective areas 920, then the X coordinate, Y coordinate, width and height of the second defective area 920, the X coordinate, Y coordinate, width and height of the third defective area 920, and so on. Just do it. Binary files have the advantage of being small in size.

Another example of the format of information to be transmitted may be a text file in XML format. In this case, the recorded image ID, which is each element, and the Y coordinate and width of the defective area are described in the tag. Since this information is in text format, unlike a binary file, there is an advantage that overflow does not occur, in which the information does not fit in the prescribed bits. Note that the number of defective areas is not limited to one as described above. If ejection failures occur in multiple nozzles at the same time, the defective regions 920 may also be in multiple locations.

In addition, the control unit 13 displays on the touch panel of the operation unit 133 that there is a recording defect to notify the user. Furthermore, if a tape inserter is provided in the post-recording process, a notification is given to insert the tape into the recording material P' in which the recording defect has occurred. As a result, the user can know which recorded matter has a defect, and can easily remove the defective recorded matter.

In S1307, imposition processing for arranging image areas while avoiding the defective area 920 and rendering are performed. In this embodiment, these processes are performed by the host device HC2 that has received the notification of the defective area. However, it is also possible to perform imposition processing and rendering processing in another device such as the host device HC1 or another computer (not shown). effect can be obtained.

Here, the procedure of the reimposition processing performed in S1307 will be described based on the flowchart of FIG. As described above, the following processing is performed by the host device HC2. In S1401, it is determined whether or not the defective area 920 is located within the range of the image forming areas 902 to 905 of the recording medium P. If it is determined that the defective area 920 is outside the range of the image forming area (if the determination result is No), the process proceeds to S1404. Also, if the defective area 920 is within the range of the image forming areas 902 to 905 (if the determination result is Yes), the process proceeds to S1402. In the example shown in FIG. 12B, the image forming areas 903 and 905 of the recording medium P and the defective area 920 overlap. Therefore, the determination result in S1401 is YES, and the process proceeds to S1402.

In S1402, it is determined whether or not it is possible to move the image forming areas 902 to 905 to avoidance positions where overlapping with the defective area 920 can be avoided. In the example shown in FIG. 12B, by moving the image forming areas 903 and 905 in the direction (±Y direction) orthogonal to the direction (X direction) in which the defective area extends, the defect is formed in the image forming area 902. In the example shown in FIG. It is determined whether inclusion of the region 920 can be avoided. In this example, only movement in the Y direction will be described for the sake of simplification of explanation, but this is not the only case. Depending on the imposition layout, it may be possible to avoid the defective area by rotating the image forming area, moving it in the Y direction, or combining rotation and movement in the X direction. Therefore, movement or rotation of the image forming area in the X direction may be added to the reimposition process. This increases the degree of freedom in imposition and increases the possibility of avoiding overlap between the defective area and the image forming area. For example, after moving the image forming area that overlaps the defective area to a position facing the blank (an area where no other image area exists) located in the X direction from the image forming area, then move the blank in the Y direction toward the blank. , it is possible to avoid overlapping with the defective area. Also, before moving the image forming area to be avoided in the X direction, first, another image forming area is moved in the X direction to create a blank space, and the image forming area overlapping the defective area is moved toward the blank space. It is also possible to move the area and avoid overlapping with the defective area. In this way, if imposition can be freely performed by combining X direction, Y direction, rotation, etc., the possibility of avoiding overlap between the defective area and the image forming area increases.

FIG. 15 is a flow chart showing an example of the determination processing performed in step S1402 described above, that is, the processing of determining whether the image forming area can be moved to the avoidance position where overlapping with the defective area can be avoided. Each process shown in FIG. 15 will be described below with reference to the example shown in FIG. Note that the processing shown in FIG. 15 is executed by the CPU 201, which is the processing unit of the host device HC2.

In S1501, the image forming areas (in the example shown in FIG. 12, the image forming areas 903 and 905) that overlap the defective area 920 are moved in the Y direction (+Y direction in this case) by one pixel. Next, in S1502, it is determined whether the moved image areas (903, 905) overlap other image forming areas (eg, 902, 904). If they do not overlap (the determination result is Yes), the process proceeds to S1503, and if they overlap (the determination result is No), the process proceeds to S1507. In S1507, the overlapping image forming areas 902 and 904 are moved. The movement is performed by the same number of pixels in the same direction as the image forming areas 903 and 905 overlapping the defective area. This can prevent the image forming areas from overlapping each other. After that, the process moves to step S1503.

In S<b>1503 , it is determined whether or not all the image formation areas protrude from the image formable area 901 . Here, the image formable area 901 refers to an area in which an image can be recorded on the recording surface of the recording medium P by the recording head 30 . In this embodiment, initial imposition and re-imposition are performed so that image formation areas 902 to 905, nozzle check patterns 906 to 909, and the like are included in the image formable area 901 (so as not to protrude). Image data corresponding to this image formable area is also called original image data.

If it is determined in the determination processing in S1503 that the image forming areas 902 and 904 do not protrude from the image forming area 901 (if the determination result is Yes), the process proceeds to S1504. Also, if it is determined that even one image formation area protrudes from the image formable area 901 (when the determination result is No), the process proceeds to S1508.

In S1504, it is determined whether all of the image forming areas 902 to 905 overlap the defective area 920 or not. If it is determined that none of the image forming areas 902 to 905 overlap the defective area (if the determination result is Yes), the process proceeds to S1505. If it is determined that there is an image forming area that overlaps with the defective area 920 (if the determination result is No), the process moves to S1501 again, and the processes of S1501 to S1504 are repeated.

Even if some of the image forming areas do not overlap the defective area 920, the determination result of S1504 is No, and the process proceeds to S1501. At this time, in S1501, among the plurality of image forming areas, the image forming areas that do not overlap with the defective area 920 are excluded from the targets of the movement processing, and only the image forming areas that overlap with the defective area 920 are moved. Also, there may be a plurality of defective areas 920 within the image formable area 901 . In this case, in S1504, it is determined whether all of the image forming areas 902 to 905 overlap with all of the defective areas 920 or not. If even one image forming area overlaps with the defective area 920, the determination result is No, and the process proceeds to S1502 to move only the image forming area that does not overlap with the defective area 920. FIG.

As a result of the determination processing in S1503, if it is determined that the image forming area protrudes from the image formable range (when the determination result is No), in S1508 it is determined that the defective area cannot be avoided, and then end the processing of the flow chart. This is because the defective area could not be avoided even if the image forming area was moved to just before it protrudes from the image data in the processing of S1501.

In S1505, it is determined that the overlapping of the defective area 920 and the image forming area can be avoided, and this effect is stored in the RAM 203, and the process proceeds to S1506. Thereafter, in S1506, the moving direction and moving distance of each image forming area are stored in the RAM 203. FIG. For example, information such as "20 pixels in the +Y direction" is stored. When the storage is finished, the first judgment processing shown in the flowchart of FIG. 15 is finished.

Note that in the present embodiment, the image forming area is moved pixel by pixel in the movement processing of S1501 for reimposition, but the present invention is not limited to this. The image forming area may be moved by a plurality of pixels (for example, two pixels). According to this, the processing speed is multiplied (approximately doubled in the case of two pixels). In addition, as a method of moving the image forming area, the distance required to move the image forming area to a position where the image forming area does not overlap the defective area may be obtained by calculation, and the image forming area may be moved by the calculated distance. . For example, the distance by which the left end of the image forming area 903 in FIG. 12A is moved to the right end of the defective area 920, that is, the distance 913 shown in FIG. You may make it move to a direction. According to this, it is possible to greatly reduce the number of calculations, and it is possible to greatly shorten the time required for the movement processing.

In the above process, if the image to be formed includes register marks or the like that are necessary in the post-process, they are also processed as an image forming area.

After the first determination process shown in the flowchart of FIG. 15 is finished, the determination process shown in the flowchart of FIG. 15 is repeated again. In the first determination process, the image forming areas 903 and 905 overlapping the defective area were moved in the positive direction (+Y direction) in the Y direction in S1501. , and do the same.

As a result of executing the first determination process and the second determination process, if it is determined in both determination processes that the overlap between the defective area 920 and the image forming areas 903 and 905 cannot be avoided, then in S1402, Finally, it is determined that the defective area cannot be avoided. In this case, the process proceeds to S1406 in FIG. 14 and the recording operation stops.

If it is determined in either the first determination process or the second determination process that the overlap between the defective area 920 and the image forming areas 903 and 905 can be avoided, then in S1402, the final defective area is determined to be defective. Determine that the area can be avoided. After that, the process moves to S1403. In this case, the movement distance stored in the RAM 203 in S1506 of the determination process that is determined to be avoidable is used in the recording position movement process in S1403 that is performed later.

If it is determined in both the first determination process and the second determination process that overlap between the defective area 920 and the image forming areas 903 and 905 can be avoided, in S1402 the defective area is finally removed. Determined as avoidable. In this case, the shorter movement distance stored in the RAM 203 is selected in the process of S1403. As a method of selecting the moving distance, a method such as giving priority to the moving distance stored in the determination process of the other image forming area where there is no movement may be adopted. When this selection method is adopted, it is possible to obtain an effect that an image with little change from the original image data can be formed. Note that if it is determined in S1402 that the defective area can be avoided (when the determination result is Yes), in S1403 the movement amount Yv required to avoid the defect is stored. This Yv also includes negative values.

In S1403, the image forming areas 903 and 905 are moved in the Y direction according to the determination result in S1402, and reimposition processing is performed. The reimposition processing will be described with reference to FIG. FIG. 12A shows images laid out by initial imposition processing, and shows a case where image forming areas 903 and 905 can be moved so as not to overlap the defective area.

The host device HC2 uses the document data associated with the image ID notified from the control unit 13 to perform re-imposition processing. In the re-imposition processing, the image forming areas arranged by the initial imposition processing are moved in the Y direction based on the movement amount Yv stored in S1403. FIG. 12B shows the state after the re-imposition process. In FIG. 12(b), 903D and 905D indicate the positions of the image forming areas after being moved from the state of FIG. 12(a). Further, 913 indicates the distance by which the image forming areas 903 and 905 are moved from the state of FIG. 9C, and this distance corresponds to the movement amount Yv described above. As described above, the host device HC2 performs re-imposition processing of the image forming area.

Note that the process of moving the position of the image forming area may be performed by the host device HC1. Alternatively, the main controller 13A or the engine controller 13B of the control unit 13 may be used. This can be realized by having the control unit 13 acquire information indicating where the image forming area is from the host device HC2. For example, the host device HC2 prepares an image having the same width and height as the image data, sets the pixel value of the image forming area to 1 and sets the other pixel values to 0, and uses the information as the positional information of the image forming area in the control unit. Tell 13. Thereby, the main controller 13A or the engine controller 13B can move the image forming area according to the received information and the information of the defective area.

As described above, in the present embodiment, when an ejection failure nozzle occurs in the nozzles of the recording head 30, reimposition is performed by moving the image forming area to a position that avoids overlapping with the defective area corresponding to the ejection failure nozzle. process. Therefore, it is possible to print a proper image without using the ejection failure nozzle, and it is possible to continue the printing operation without performing maintenance for eliminating the ejection failure of the nozzle. Here, maintenance includes recovery operation by the recovery unit 12 described above, replacement of the recording head 30, and the like. In the case of the thermal ink jet system, when maintenance is performed, the color of the recorded image may change compared to when the recording operation is performed continuously. This is for the following reasons.

In the recovery unit 12, maintenance is performed to restore the ejection performance of the nozzles by sucking the ink in the recording head 30 from the ink ejection surface under negative pressure. In this maintenance, the ink flowing through the nozzle cools the heater inside the nozzle. As a result, when the printing operation is started again, an electric pulse is supplied to the heater at a temperature lower than that in the state where the ejection is continued. That is, electric power is supplied to the heater according to the electric pulse. In this case, the state of film boiling of the ink in the nozzle changes, causing a minute change in the amount of ink ejected compared to the case of continuous recording, and this causes a subtle change in the color of the recorded image. Become.

Also, when the printhead is replaced, the amount of ink ejected from the nozzles may change due to variations in the production of the printhead. In addition, since the temperature of the nozzles is lower than in the case of continuous printing, there is a slight difference in the amount of ink ejected compared to the case of continuous printing. As a result of changes in the amount of ink ejected, subtle differences occur in the colors of recorded images. For this reason, when a plurality of products such as books are displayed side by side as commodities, for example, since humans have high visual sensitivity, they will perceive subtle differences in color between the adjacently arranged products. In this embodiment, since continuous printing is possible without maintenance, it is possible to suppress the color difference that occurs between products.

Next, the ejection changing process for the defective area performed in S1404 of FIG. 14 will be described. The process of S1404 is executed when it is determined in S1401 that the defective area is not within the range of the image forming area and when the process of S1403 is finished.

FIG. 11 shows images printed when the host device HC2 performs initial imposition processing. b) shows images recorded by the recording head 30 in which ejection failure occurred. In the image shown in FIG. 11(a), the nozzle check patterns 906 to 909 are all printed in a proper state without omission. On the other hand, in the nozzle check patterns 906 to 909 shown in FIG. 11B, some nozzles of the print head that eject magenta ink have ejection failures, resulting in color loss. In S1404, the image data of the nozzle check pattern in the defective area including the ejection failure nozzle is changed to reduce the ejection frequency of the failure nozzle. Specifically, the print data corresponding to the defective area of the nozzle check pattern of the ink color (here, magenta) in which the ejection failure occurs is changed to the non-ejection direction. In this embodiment, the control unit 13 changes the magenta ejection data in the magenta nozzle check pattern 907 from 1 (ejection) to 0 (non-ejection).

On the other hand, when the host device HC2 performs this processing, the host device HC2 performs processing to increase the brightness of the image data in the magenta nozzle check pattern 907 .

In this embodiment, the luminance value dRGB of the image data (pixel value) corresponding to the defective area 920 is changed to the highest luminance value. The image data of dRGB with the highest value represents white. ink is not ejected. That is, the heaters of the plurality of nozzles corresponding to the defective area 920 are not supplied with electric pulses for driving them, and are not heated. FIG. 12B shows the result of printing without supplying electric pulses to the plurality of heaters corresponding to the defective areas. As shown in FIG. 12B, in the magenta nozzle check pattern 907, ink is not applied to the portions corresponding to the defective areas 920, and the background color (for example, white) of the recording medium P appears. is formed. As described above, the defective region 920 is a region corresponding to a plurality of nozzles including a defective ejection nozzle. Therefore, the width of the color missing portion W1 shown in FIG. It is larger than the width of the color missing portion W corresponding only to the ejection failure nozzle.

Thus, the electric pulse is not supplied to the heaters of the nozzles corresponding to the ejection failure region. In other words, the amount of power supplied to the defective nozzle is set to zero. As a result, it is possible to suppress the occurrence of burnt deposits in nozzles with ejection failures, and it is possible to extend the life of the nozzles and, by extension, the life of the recording head 30 .

Burnt deposits in the nozzles are caused by the heat of the heater burning ink components such as coloring materials remaining in the nozzles, and are likely to occur in nozzles that are defective in ejection. For example, if an electric pulse is continuously supplied to a heater in a nozzle in which air bubbles are mixed in the nozzle and ink is not properly supplied and the nozzle is in an ejection failure state, the inside of the nozzle will be overheated by the heat of the heater, causing kogation. is likely to occur. Even after the bubbles in the flow path are eliminated by maintenance and the ink supply is restored, the kogation becomes a factor of unstable ejection, non-ejection, and an abnormality (distortion) in the ejection direction. In the present embodiment, the supply of electric pulses to the defective nozzle is set to 0 by the process of S1404 described above, thereby suppressing the occurrence of kogation in the nozzle.

In the ejection change process for the defective area described above, the supply of pulses to the nozzles corresponding to the defective area 920 is completely cut off for the recording head 30 in which the ejection defect has occurred. Although an example in which ink is not ejected has been shown, the present invention is not limited to this. For example, for the recording head 30 in which an ejection failure has occurred, the frequency of supplying electrical pulses to the nozzles corresponding to the defective area 920 is set to 1/N (N> 1) is also possible. That is, in the nozzle check pattern forming area, the number of ink ejections (the number of ink droplets) for the portion corresponding to the defective area may be set to 1/N the number of ink ejections for the portion not corresponding to the defective area. In this case, the density of the portion corresponding to the defective region is lower than the density of the other portions.

Note that in this embodiment, the nozzle check pattern is arranged in all image data. Therefore, when there is no ejection failure nozzle, the nozzles in the other portions (non-overlapping portions) except for the overlapping portions of the ejection substrates eject the ink one or more times for one printed matter P′. will be discharged. Therefore, if the ejection frequency of the nozzles corresponding to the defective area is set to 1/N, one or more electrical pulses are supplied when N sheets of the printed material P' are printed. In other words, this is the number of ejections for one sheet performed by normal nozzles.

In this way, even if the supply frequency of the electric pulse supplied to the nozzle corresponding to the defective area is set to 1 or less instead of 0, it is possible to reduce the occurrence of kogation in the ejection failure nozzle. Note that the value of N can be set arbitrarily. If at least the ratio (1/N) to normal recording is less than 1.0, the effect can be obtained.

Further, as shown in FIG. 3, in the recording head 30 in which the adjacent ejection substrates are arranged in a partially overlapping state, nozzles corresponding to the defective area are formed in the overlapping portion and the non-overlapping portion of the ejection substrates. may be different. There are two nozzles in the non-overlapping nozzle columns (m-p) shown in FIG. 3, and there are four nozzles (i-l) in the overlapping nozzle columns. For this reason, if there is a defective ejection nozzle in the overlapping portion, the number of ejections in the defective region is set to 1/2 the number of ejections in the other regions. The number of ejections in is set to 1/4. This is because the number of ejections from each nozzle in the overlapping portion is half the number of ejections from each nozzle in the non-overlapping portion even when there are no ejection failure nozzles.

In general, in an ink jet printing apparatus, nozzles that are not ejecting ink during a printing operation are exposed to the air, and are therefore easily dried. If the solvent or water in the ink in the nozzle evaporates, the thickened or solidified ink may adhere to the nozzle and cause ejection failure. Therefore, maintenance is performed, which consumes a lot of time and ink. Therefore, it is desirable that the nozzle periodically discharges fresh ink before volatilization. However, if electric pulses are continuously supplied to nozzles in which ejection failure occurs as described above, the possibility of scorching will increase. On the other hand, as described above, the frequency of supplying electric pulses to the nozzle check pattern is not set to 0, but is set to be reduced from the normal number of ejections. It is possible to reduce sticking.

In addition, in this embodiment, the frequency of supplying electric pulses is controlled not on a nozzle-by-nozzle basis, but on a defective area composed of a plurality of nozzles including an ejection-defective nozzle, in consideration of the printing speed and the resolution of the reading device. . For this reason, there is a possibility that normal nozzles are included in the defective area. It is also possible to reduce sticking due to drying of normal nozzles.

Small bubbles in the nozzle may prevent the ink from being supplied, resulting in ejection failure. In this case, the bubbles disappear with time, ink is supplied, and the ejection performance may recover. Therefore, the density in the defective area is monitored by the inspection unit 9A or the like, and when the detected density continues to reach the predetermined density, the control for the nozzle corresponding to the defective area is canceled and the nozzle is returned to normal operation. You may make it return to discharge operation. In this case, the higher-level device HC2 may restore the initial imposition state as shown in FIG. 11A and perform recording. According to this, it is possible to further reduce the drying of the nozzles and the solidification of the ink, compared to the case where the number of ejections from the nozzles corresponding to the defective area is continuously decreased.

In addition to non-ejection, in which ink is not ejected from the nozzles, ejection defects that occur in the nozzles of the print head include a phenomenon called deflection, in which an abnormality occurs in the ejection direction of ink. If the ejection failure is not an ejection failure but a twist, the ink will land (land) in a place other than the place where the ink should have originally been shot. There is a possibility that the destination of the ejection in the abnormal ejection direction is the location where the ink ejected by the normal nozzle lands, and the amount of ink that is doubled as expected is ejected at that location. Excessive amount of ink causes blurring and poor transfer to paper, which can stain the transfer body. Also, even in a recording apparatus that directly records from a nozzle onto a recording paper without using a transfer member, there is a possibility that the ink receptor on the paper will not be able to absorb an amount of ink larger than expected, causing the ink to overflow. Spilled ink can cause smearing on machines and other recordings.

In this embodiment, the process of S1104 is also performed for nozzles that cause skew, thereby lowering the ejection frequency and thereby reducing the probability of staining the printing apparatus and other printed matter. It is possible to reduce various inconveniences caused by twisting. Further, when it is determined that the ejection failure is skew, the frequency of electric pulse supply to nozzles other than the image forming area such as the preliminary ejection and the nozzle check pattern is reduced, but not set to zero. In other words, the amount of electric power to the nozzle is not reduced to 0, but is reduced from the normal amount. As a result, it is possible to reduce adhesion of ink due to drying of the nozzles.

Note that twist can be detected from a read image or the like. For example, if one nozzle on the read image is faint and a certain location in the neighborhood is dark, the ink has landed at a location different from where it should originally have landed. As a result, it can be determined that the thinned portion of the nozzle is twisted. In addition, it can be determined that ejection failure occurs when there are places where the ink is thin but there are no places where it is thick. In addition, when the head temperature is monitored, it is not non-ejection, but when one nozzle on the read image is thin, it can also be determined as misalignment. Further, by providing an infrared sensor or a visible light sensor and optically examining whether or not the ejection of the nozzles is normal, it is possible to specify the nozzles causing the twist.

After finishing the above processing of S1404, the processing advances to step S1405. In S1405, a signal indicating continuation of the printing operation is stored in the RAM 203 in response to the execution of the processing in S1404. Then, the processing of the flowchart of FIG. 11 ends.

If the determination result in S1402 is No, the process advances to S1406 to stop the printing operation, and a signal to stop the printing operation is stored in the RAM 203. FIG. This is to prevent the recording operation from being performed later, because the defective area cannot be avoided even if the image forming area is moved, and a defective recorded matter P' is recorded. After the recording operation is stopped, the processing of the flowchart of FIG. 14 ends.

After the processing in FIG. 14 is completed, in S1307 in FIG. 13, if there is image data after reimposition, the image data is rendered. Then, when the process of S1307 ends, the process proceeds to S1308. In S1308, based on the signal stored in the RAM 203 in S1405, the host device HC2 determines whether or not to continue the recording operation. Here, when the signal for continuing the recording operation is stored in the RAM 203 , the host device HC 2 transmits the rendered image data to the control unit 13 . In addition, the host device HC2 creates information required in the post-process, such as the cutting position, and transmits it to the paper-cutting machine 141 in the post-process 140 together with the image data ID. As a result, the cutting machine 141 can cut the printed matter P' according to the new cutting position after moving the image forming area.

As shown in FIG. 12B, when the image forming area is arranged at a position that does not overlap with the defective area 920 within the image formable range 901, if the recording medium and the image forming area are the same, the following operations will be performed. The image forming area of the input original image data can also be moved in the same manner. Therefore, subsequent imposition of other original image data can be performed with the same layout, eliminating the need for arithmetic processing for imposition.

If it is determined in S1308 that the recording operation should be continued, the process proceeds to step S1302 and the recording operation is performed. At this time, the frequency of supplying electric pulses to the heater corresponding to the defective area is reduced by the re-imposition processing in S1307 and the ejection change processing in S1404. Therefore, the possibility of occurrence of burnt deposits on the nozzles corresponding to the defective area is reduced. Also, if the signal for continuing the recording operation is stored in the RAM 203, the process proceeds from S1308 to S1310.

In S1310, the main controller 13A stops the recording operation, and displays a message indicating that the recording operation has been stopped on the touch panel of the operation unit 133 to inform the user. Here, the series of processing shown in the flowchart of FIG. 13 ends.

After the recording operation is stopped, maintenance is performed by the user's operation to eliminate defects that have occurred in the defective area, and re-recording is performed. It should be noted that maintenance may be performed automatically and re-recording may be performed. According to this, the user's trouble can be reduced.

In S1309, cutting is performed by the cutting machine 141 as a post-process 140. FIG. In the post-process, the recorded material P' is cut, and the image within the image forming area is used as a product. As described above, the cutting machine 141 of the post-process 140 receives the image data ID and information necessary for the post-process from the host device HC2. Therefore, even when the image forming area moves, it is possible to perform correct processing. For example, even if the cutting position is changed due to movement of the image forming area, the cutting can be performed at the correct position.

As described above, in the present embodiment, when printing an image forming area, reimposition is performed while avoiding the defective area, thereby stopping the supply of the electric pulse to the heater of the ejection failure nozzle. Also, when printing the nozzle check pattern, the supply of electrical pulses to the heaters of the ejection failure nozzles is reduced. By reducing the amount of power supplied to the ejection failure nozzles in this way, it is possible to reduce the occurrence of scorching in the ejection failure nozzles. Further, in this embodiment, when forming a nozzle check pattern that is not used as a product, a small number of pulses are supplied without completely stopping the supply of electrical pulses to a plurality of nozzles corresponding to defective areas. As a result, it is possible to promote the flow of ink and the disappearance of air bubbles in the ejection failure nozzles existing in the defective area, and it is possible to eject the ink in the normal nozzles. Therefore, it is possible to suppress the drying and solidification of the ink in the ejection failure nozzles and the normal nozzles existing in the failure area.

Furthermore, by imposing the image forming area while avoiding the defective area, image deterioration such as color loss does not occur in the product. In addition, it is possible to continue the printing operation while reducing the frequency of print head replacement and maintenance caused by the occurrence of ejection failure, and it is possible to suppress the occurrence of subtle color changes in the image. In addition, productivity and running costs can be improved.

[Second embodiment]
Next, a second embodiment of the present invention will be described with a focus on differences from the first embodiment.

In the first embodiment described above, it is determined whether or not the image forming area can be moved to a position that does not overlap with the defective area (S1402). On the other hand, in the present embodiment, it is determined whether or not the image forming area can be moved to a position where the recording image (ink image) in the image forming area does not overlap the defective area, and the recording operation is performed based on the determination result. to continue or stop the recording operation.

FIG. 16 is a diagram for explaining the process of moving the defective area including the defective ejection nozzle and the image forming area when the defective ejection nozzle occurs. In FIG. 16A, 1301 corresponds to the image formable area of this embodiment. Reference numeral 1302 denotes an image forming area of this embodiment. A capital letter "ABCD EFGH" 1303 is a printed image (ink image) printed in red using magenta ink and yellow ink. A lowercase alphabet 1304 is a print image (ink image) that is printed only with black ink. A rectangular area represented by a dashed line 1305 is the defective area determined in S1306 of FIG. In this example, a printing head that ejects magenta ink has an ejection failure nozzle, and a plurality of nozzles including the ejection failure nozzle correspond to the defective area. 1306 to 1309 are nozzle check patterns for cyan, magenta, yellow and black inks, respectively.

When forming a print image in the image forming area 1302, also in this embodiment, the nozzles (in this example, the nozzles for ejecting magenta ink) corresponding to the defective areas of the print head including the ejection failure nozzles are Do not apply electrical pulses. Therefore, if the image forming area 1302 and the defective area 1305 are in the positional relationship shown in FIG. 16A and the printing is performed as it is, as shown in FIG. A defect (color loss) occurs in the part of

As described above, in the first embodiment, it is determined whether the image forming area can be moved within a range that does not protrude from the image formable area 901 to avoid overlapping with the defective area. On the other hand, in the example shown in FIG. 16A, no matter how the image forming area 1302 is moved within the range of the image forming area 1301, the overlap between the image forming area 1302 and the defective area 1305 is avoided. you can't.

Therefore, in the present embodiment, the image data after color separation is acquired, and the image forming area is changed to the image forming possible area so that the position where printing is performed using the magenta ink with ejection failure and the defective area 1305 do not overlap. It is determined whether it can be moved within the range of 1301 .

As in the processing flow shown in FIG. 15, while moving the image forming area 1302 pixel by pixel in the Y direction, it is determined whether or not the overlap between the defective area 1305 and the printed image 1303 using magenta ink can be avoided. The difference between the present embodiment and the first embodiment is that in the process of S1504, it is determined whether or not the image forming area overlaps the defective area, whereas in the present embodiment, the magenta print image after color separation is determined. It is determined whether the (ink image) overlaps the defective area 1305 or not.

FIG. 16C is a diagram showing an example in which the image forming area is moved to an avoidance position that can avoid overlapping of the printed image 1303 using magenta ink and the defective area 1305 . Here, by moving the image forming area 1302 in the +Y direction, a capital letter 1303 using magenta ink is arranged so as not to overlap the defective area 1305 . On the other hand, the lower case alphabet 1304 overlaps the defective area, but since magenta ink is not used, the image can be properly printed.

In the magenta nozzle check pattern 1307 shown in FIG. 16C, the magenta ejection data in the magenta nozzle check pattern 1407 is changed from 1 (ejection) to 0 (non-ejection), as in the first embodiment. When this process is performed by the host device HC2, the pixel value of the image data is set to white (R, G, and B are the highest values), and the frequency of supplying electric pulses to the nozzles for ejecting magenta ink corresponding to the defective area is to 0. In other words, no electric pulse is supplied. However, as in the first embodiment, when printing the nozzle check pattern of the ink color (here, magenta) in which the ejection failure occurs, the frequency of supplying electric pulses to the nozzles corresponding to the defective area 1305 is set to 0. Not limited. If the ejection frequency is set to less than 1.0 with respect to the ejection frequency before performing the ejection change process, the effect of suppressing the occurrence of kogation can be obtained.

As described above, in the present embodiment, in printing a print image and a nozzle check pattern in an image forming area, by reducing the frequency of electric pulse supply to the ejection failure nozzle to 0 or reducing it, It is possible to suppress the occurrence of scorching.

In addition, since the image forming area is moved to a position where the recording image in the image forming area and the defective area do not overlap, the recording operation is performed. be able to. Therefore, the possibility of avoiding the defective area increases, and as a result, the possibility of continuing the recording operation increases. That is, it becomes possible to further reduce the frequency of replacement and maintenance of the recording head, to further suppress the occurrence of subtle color changes in images, and to further improve productivity and running costs. can be done.

[Third embodiment]
Next, a third embodiment of the invention will be described. This embodiment will also be described with a focus on differences from the above-described embodiment.

In the above-described first and second embodiments, examples have been described in which the frequency of supplying electrical pulses to the nozzles is reduced by changing the recorded image. That is, in the above-described embodiment, an example has been described in which the image data corresponding to the defective area is changed to white or low-density magenta in the nozzle check pattern printed by the nozzle in which the ejection failure has occurred.

On the other hand, in the present embodiment, the recording control unit 15A shown in FIG. 5 performs control to reduce the frequency of supplying electric pulses to nozzles corresponding to defective areas. Therefore, in the process of changing ejection in the defective area in S1404 of FIG. 14, the process of changing the brightness of the image data representing the nozzle check pattern is not performed. Instead, the recording control unit 15A is informed of the position of the defective area, the defective ejection color (magenta), and the reduction rate (1/N) of the electric pulse supply frequency. Here, the reduction rate means the ratio between the frequency of supplying electrical pulses to nozzles in which ejection failure does not occur and the frequency of supplying electrical pulses to nozzles corresponding to defective areas during formation of the nozzle check pattern. .

In the binarization process of S707 in FIG. 7, the print control unit 15A performs the process of reducing the ejection frequency of the nozzles corresponding to the defective area. For example, when the magenta electric pulse supply frequency in the defective area is halved, the magenta value of dCMYK''' is stochastically halved for the nozzle corresponding to the defective area. Probability 1/2 means, for example, that when the value is 0, it is treated as 0, and when the value is 1, it is treated as 1 at 50% and 0 at 50%. When the value is 2, it is treated as 1.

As another example, when the ejection frequency is set to 1/N, the error of the initial value is set to 0 in the halftone processing S706, the value of dCMYK''' is multiplied by 1/N, and the halftone processing is already completed for that value. Add the errors generated in adjacent pixels. Treat the integer part as a new dCMYK''' and add the decimal part to the error. By distributing the error to the next pixel value in the X direction in this way, it is possible to stochastically reduce the frequency of supplying electric pulses to 1/N.

Further, the frequency of supplying electric pulses to the nozzles may be lowered for all the inks of the nozzles corresponding to the defective area. As a result, it is sufficient to transmit only the position of the defective area to the recording control section 15A which performs the binarization process, thereby facilitating control.

As another example, control to reduce the frequency of supplying electric pulses to nozzles in defective areas (for example, to 1/N), one of the following processes, or the above binarization process, image data generation, etc. It may be done at multiple locations, including

Any one of ink color separation in S703 of FIG. 7, gamma correction in S704, and head shading in S705 may be performed. When referring to the LUT and outputting dCMYK, a value obtained by multiplying the dCMYK value by 1/N is output for the ejection failure color (magenta) in the failure area. Alternatively, an LUT that outputs a value of 1/N may be prepared in advance, and the LUT may be referred to for the ejection failure color in the failure area.

Alternatively, halftone processing in S706 may be performed. For ejection failure colors in the failure area, the values of the threshold matrix to be compared may be multiplied by N. Alternatively, the output multilevel value may be multiplied by 1/N and output.

In the processing method described above, since the correlation with the number of dots to be ejected increases toward the downstream in the flow chart of FIG. 7, it is possible to more accurately reduce the frequency of supplying electric pulses to the nozzles. .

As described above, in this embodiment, when forming a check pattern, the recording control unit 15A located downstream of the image processing performs processing to reduce the frequency of supplying electric pulses. As a result, it is possible to more accurately reduce the frequency of supplying electric pulses to the nozzles corresponding to the defective area, and to more reliably reduce the burning of the nozzles. Further, if the frequency of discharging electric pulses to the nozzles corresponding to the defective area is not set to 0 but is reduced, it is possible to suppress the drying and solidification of the ink in the nozzles.

[Fourth embodiment]
Next, a fourth embodiment of the invention will be described. This embodiment will also be described with a focus on differences from the above-described embodiment.

In the first to third embodiments, as shown in FIG. 1, ink is ejected from the recording head 30 onto the transfer body 2 to form an ink image, and the ink image is transferred from the transfer body 2 to the recording medium P. By doing so, an image is recorded. On the other hand, the printing apparatus according to the present embodiment performs printing by ejecting ink directly from the printing head onto the printing paper. In the above embodiment, the ink ejection operation for forming the nozzle check pattern also serves as preliminary ejection for maintaining and recovering the ejection performance in the nozzles. On the other hand, in the present embodiment, the nozzle check pattern is not formed on all print media, but is formed on each of a predetermined number of print media, and by reading the nozzle check pattern, an ejection failure nozzle is specified. . In a printing operation on a printing medium on which no nozzle check pattern is formed, preliminary ejection is performed to preliminary ejection grooves provided facing the lower portion of the print head.

In the printing apparatus of this embodiment configured as described above, all the nozzles of the printing head perform preliminary ejection to the preliminary ejection grooves every time the printing operation for the printing medium on which the nozzle check pattern is not formed is completed. As a result, fresh ink passes through the nozzles, and drying and solidification of the ink in the nozzles can be suppressed.

Further, in this embodiment, unlike the first embodiment, the change processing (S1404) for the image data of the nozzle check pattern is not executed. Instead, information such as the position of the nozzle corresponding to the defective area obtained based on the result of reading the nozzle check pattern, the defective ejection color, and the decrease rate (1/N) of the supply frequency of the electric pulse is sent to the recording control unit 15A. Send.

When the printing operation for one sheet of printing medium on which the nozzle check pattern is not printed is completed, the print head 30 performs preliminary ejection to the preliminary ejection grooves according to the command from the printing control section. At this time, control is performed so that the frequency of supplying the electric pulse is 1/N for the nozzle corresponding to the defective area in the recording head in which the ejection failure nozzle exists. As a result, it is possible to suppress the occurrence of burnt deposits in the ejection failure nozzle even when the preliminary ejection operation is performed in the preliminary ejection groove. Further, if a small amount of ink is ejected from the nozzles corresponding to the defective area, it is possible to suppress the drying and solidification of the ink inside the nozzles.

[Fifth embodiment]
Next, a fifth embodiment of the present invention will be described. This embodiment will also be described with a focus on differences from the above-described embodiment.

In the above embodiment, a full-line type recording apparatus has been described as an example, but the present invention is not limited to this. For example, a serial type that prints an image on a print medium by ejecting ink while intermittently moving the print medium in a predetermined direction and reciprocally scanning the print head in a direction that intersects the conveying direction of the print medium. The present invention can also be applied to the recording apparatus of

FIG. 17A is a diagram for explaining a serial type recording method. A print head 1501 is formed with a plurality of nozzle rows corresponding to a plurality of different inks. In this embodiment, a cyan nozzle row 1511 that ejects cyan ink, a magenta nozzle row 1512 that ejects magenta ink, a yellow nozzle row 1513 that ejects yellow ink, and a black nozzle row 1514 that ejects black ink are arranged in the Y direction. is set. In each nozzle row, a plurality of nozzles are arranged at regular intervals along the X direction perpendicular to the Y direction, and printing is performed by ejecting ink onto the printing medium P from each nozzle.

Under the control of the print control unit, the print head 1501 prints on the print medium P by ejecting ink while scanning the print medium P along the Y direction (for example, the +Y direction). A recovery unit is provided at the end of the movement path of the recording head 1501 . When print head 1501 reaches the end of the travel path, print head 1501 is positioned over the recovery unit. When the check pattern is not printed, each nozzle of the print head 1501 performs preliminary ejection to the recovery unit under the control of the print control unit.

Next, the transporting means for the recording medium P transports the recording medium P by a predetermined amount in the X direction under the control of the transport control section. When the print medium is conveyed by a predetermined amount, the print head 1501 performs printing by ejecting ink while scanning the print medium P again in the Y direction (for example, the -Y direction). As described above, the serial type printing apparatus prints on the printing medium P while repeating the intermittent conveying operation of the printing medium and the scanning of the printing head. Note that this example shows a so-called one-pass printing method in which an image in an area corresponding to the width of the printhead in the X direction is completed by one scan of the printhead.

FIG. 17B shows a case where the nozzle at the position 1503 in the cyan nozzle row 1511 of the print head 1501 has an ejection failure. When a printing operation is performed with the printing head 1501 in which the ejection failure has occurred, image deterioration such as color loss occurs in the area indicated by the dashed line 1505 in the figure.

Further, in FIG. 17B, 1504 denotes an image forming area set on the print medium P, and 1504 denotes a defective area corresponding to a plurality of nozzles including the ejection failure nozzle occurring in the print head. showing. In this example, the defective area 1505 does not overlap the image forming area 1504 . Therefore, the recording operation is continued in this state. When print head 1501 reaches the end of the travel path, print head 1501 is positioned over the recovery unit. At that time, normally all the nozzles perform preliminary ejection to the recovery unit, but in this embodiment, an electric pulse is supplied to the nozzles in the defective area 1505 in the cyan nozzle row 1511 including the defective ejection nozzles. Set the frequency to 0 or reduce it. Therefore, the heat generated by the preliminary ejection can be reduced, and the occurrence of burnt deposits in the ejection failure nozzle can be suppressed.

The ejection failure nozzle and the failure area can be identified by recording a nozzle check pattern on a separate sheet, optically reading it with an inspection unit, and performing the same processing as in the first embodiment. Further, when the defective area overlaps the image forming area, the image forming area may be re-imposed while avoiding the defective area as in the first embodiment.

Also, FIG. 18 shows an example of performing a recording operation using another recording method.

Similarly to FIG. 17B, FIG. 18A also shows the case where the nozzle at the position 1503 in the cyan nozzle row 1511 has an ejection failure.

As described with reference to FIG. 17A, when printing is performed by repeating the movement of the print head 1501 and the movement of the print medium P, the defective area 1505 passes over the print medium P many times. In this case, the print control unit performs control to use only the nozzle group 1507 in which the ejection failure does not occur among the nozzles in the print head 1501 . For simplicity of explanation, the nozzle group 1507 is half the length of each nozzle row. Further, the transport control unit controls the transport means to perform transport by a transport distance corresponding to the length of the nozzle group 1507 .

FIG. 18B shows the positional relationship between the recording head and the recording medium P when the recording operation is performed by the above control. In the example shown in FIG. 18(a), the transport distance of the recording medium P at one time is 1/2 of the example shown in FIG. 17(a). Also, the number of scans of the print head 1501 with respect to the print medium is doubled in the example shown in FIG. 17(a). While scanning the print head 1501 and conveying the print medium P in this way, ink is ejected from the nozzle group 1507 of the print head to print on the print medium P. FIG.

Further, when the print head 1501 reaches the recovery unit, preliminary ejection is performed to the recovery unit as described above. At this time, the frequency of supplying the electric pulse to the nozzles in the defective region 1503 in the ejection port array (cyan nozzle array 1511) including the ejection failure nozzle is set to 0 or reduced. As a result, it is possible to reduce the possibility that kogation will occur in the ejection failure nozzle during the preliminary ejection even when the printing operation is performed by the printing method shown in FIG.

In the above description, for the sake of simplicity, the length of the nozzle group 1507 is assumed to be half the length of the entire length of each nozzle row, and an example in which only this nozzle group 1507 is used has been shown. is not limited to For example, if there is no ejection failure in a nozzle group consisting of two-thirds of consecutive nozzles in a nozzle row, it is possible to use that nozzle group for printing. In this case, it is sufficient to set the length corresponding to the length of the nozzle group to be used for the conveying distance of the recording medium once. According to this, it is possible to perform high-speed printing as compared with the case of using 1/2 nozzles of the nozzle array.

Further, in the case of multi-pass printing, in which printing is performed by passing different nozzle groups set in the print head multiple times to the same location on the printing medium, only the ejection failure nozzles are not used, and other nozzles are used. It is also possible to print with other nozzles at the appropriate timing. In this case, in the preliminary ejection operation, the frequency of supplying the electrical pulse to the ejection failure nozzle is reduced to 0 or less than 1. According to this, in addition to the effect of improving the image quality and the effect of complementing the ejection failure nozzle by the multipass, the effect of suppressing the occurrence of kogation in the ejection failure nozzle can be obtained.
[Sixth embodiment]
Next, a sixth embodiment of the invention will be described. This embodiment will also be described with a focus on differences from the above-described embodiment. In FIG. 19A, 1602 to 1605 denote image formation areas, and 1606 denotes a defect area set in the same manner as in the above embodiment.

In the first embodiment, in S1402, it is determined whether or not the overlap with the defective area can be avoided by moving the image forming area, and if it is determined that it cannot be avoided, the printing operation is stopped. For example, as shown in FIG. 19A, in the image forming areas 1603 and 1605 overlapping the defective area 1606, even if they are moved within the image forming area 1601, the overlap with the defective area 1606 can be avoided. you can't. In such a case, in the first embodiment, processing for stopping the recording operation is performed.

On the other hand, in the present embodiment, the following processing is performed when overlapping with the defective area 1606 cannot be avoided even if the image forming area 1603 is moved. That is, as in the first embodiment, the process of S1402 in FIG. 14 is performed, and it is determined that the overlapping of the image forming areas 1603 and 1605 and the defective area 1606 cannot be avoided. In this case, in S1403, the host device HC performs processing for arranging the image forming areas 1603 and 1605 on a recording medium different from the image forming areas 1601 and 1604. FIG. Specifically, as shown in FIGS. 19B and 19C, the image data is stored so that the image forming areas 1602 and 1604 are arranged on the recording medium 1601B1, and the image forming areas 1603 and 1605 are arranged on the recording medium 1601B2. to create Then, the image data is sent to the main controller 13A. Furthermore, information about the created image data is also sent to a post-process (for example, a cutting machine). As a result, in the post-process, it becomes possible to perform appropriate processing on the recorded matter P'. For example, when gloss processing or cutting processing is performed in a post-process, it is possible to perform gloss processing or cutting processing at appropriate positions on the recorded matter P'. Note that if the defective area cannot be avoided even if the image forming area is divided into a plurality of recording media and printed, the process advances from S1402 to step S1406 to issue an instruction to stop the printing operation.

As described above, according to the present embodiment, by dividing the image forming area into a plurality of recording media, it is possible to avoid overlapping of the defective area and the image forming area. By eliminating the overlap between the defective area and the image forming area, it becomes possible to properly record the image in the image forming area without causing omissions such as missing colors, and to supply electric pulses to the defective area. It becomes possible to reduce the frequency. Also, although not shown in FIG. 19, a nozzle check pattern is recorded in the margin of the recording medium P or the like, and by optically reading it with an inspection unit, a defective ejection nozzle can be detected. After the defective nozzle is detected, the defective area is determined in the same manner as in the first embodiment, and the frequency of supplying electric pulses to the defective area is reduced. According to this, in both the printing operation in the image forming area and the printing operation of the nozzle check pattern, the frequency of supplying the electric pulse can be reduced to 0 or reduced, and the occurrence of burnt deposits in the ejection failure nozzle can be prevented. can be suppressed. In addition, since the printing operation can be continued without performing maintenance such as ink suction by the recovery unit, it is possible to reduce the occurrence of minute color changes in the product.

[Other embodiments]
In the above-described embodiment, the frequency of supplying electric pulses is reduced for ejection to the nozzle check pattern and preliminary ejection grooves, but the present invention is not limited to this. For example, even in in-plane preliminary ejection, in which preliminary ejection is performed approximately evenly over the entire recording medium P, the occurrence of burnt deposits in the nozzles can be suppressed by reducing the frequency of supply of the electric pulse, which is an ejection command, for the defective area. can be done.

Also, in the first embodiment, the nozzle check pattern formed on the printed material P' is read, but other methods can also be used. For example, a camera capable of imaging the transfer body 2 may be installed, and an ink image such as a nozzle check pattern recorded on the transfer body 2 may be read by the camera to detect ejection failure nozzles. In this case, if the nozzle check pattern recorded on the recording medium P' is further read, it is possible to determine whether it is an ejection failure or an abnormality in the subsequent process (for example, transfer failure or damage to the recording medium). Become. For example, if there is color loss on the recording medium P' that is not present in the ink image on the transfer member 2, it can be determined that the cause of the color loss is not nozzle failure.

Also, the frequency of ejection commands to be reduced for defective areas may be changed for each ink. Depending on the solvent and density used, the ink may vary in how easily it dries. Therefore, if the nozzle that ejects hard-to-dry ink has an ejection failure, the frequency of supplying electric pulses is reduced or set to zero. Conversely, if a nozzle that ejects ink that dries easily is defective in ejection, the reduction rate of the frequency of supplying electric pulses is reduced.

In addition, if the nozzle that ejects ink that is highly viscous and tends to burn is defective in ejection, the frequency of supplying the electric pulse is further reduced or set to zero. Conversely, if the nozzles of the ink with low viscosity and non-stick ink have ejection failure, the reduction rate of the electric pulse supply frequency may be decreased. In this manner, the rate at which the electric pulse supply frequency is reduced may be determined based on the characteristics of the ink in the nozzle that has an ejection failure. According to this, it is possible to perform processing suitable for the characteristics of each ink, and the effect of suppressing the occurrence of burnt deposits and sticking in the nozzles is further improved.

Although the image forming area and the nozzle check pattern are arranged on the recording medium P' in the first embodiment, the present invention is not limited to this. For example, when printing an image forming area on one sheet and printing a nozzle check pattern or a colorimetry chart for checking colors on the next sheet, the frequency of supplying electric pulses as described in the above embodiment is set. A similar effect can be expected by controlling.

Similar effects can also be obtained when continuous recording is performed on roll paper or the like. When printing a pattern, such as a nozzle check pattern, that is effective as a preliminary ejection between a plurality of or a single image forming area, the same effect can be obtained by reducing the frequency of supplying electric pulses to the defective area. .

Although the recording unit 3 has a plurality of recording heads 30 in the above embodiment, it may have a single recording head 30 and perform monochrome recording.

The transport mechanism for the recording medium P may be another system such as a system in which the recording medium P is nipped and transported by a pair of rollers. In a method in which the recording medium P is conveyed by a pair of rollers, a roll sheet may be used as the recording medium P, and the roll sheet may be cut after the transfer to produce the recorded matter P'.

In the above-described embodiment, the transfer body 2 is provided on the outer peripheral surface of the transfer drum 41, but other systems such as a system in which the transfer body 2 is formed in an endless strip and run cyclically may be used.

Further, the present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus reads and executes the program. It can also be realized by processing to It can also be implemented by a circuit (for example, ASIC) that implements one or more functions.

30 recording head n nozzle P recording medium 9A inspection unit 13 control unit HC2 host device

Claims (17)

a recording unit that includes a plurality of nozzles having electrothermal conversion elements, and performs recording on a recording medium by ejecting a predetermined amount of ink from the nozzles due to heat generated by the electrothermal conversion elements;
detection means for detecting, from among the plurality of nozzles, an ejection failure nozzle in which the predetermined ink ejection is not normally performed due to heat generated by the electrothermal conversion element;
Electric power supplied to the electrothermal conversion element of the ejection failure nozzle is reduced from a normal amount of electric power supplied to the electrothermal conversion element of the normal nozzle that normally ejects the predetermined ink due to the heat generated by the electrothermal conversion element. a control means;
A recording device comprising: 2. A recording apparatus according to claim 1, wherein said control means sets the amount of electric power supplied to said electrothermal conversion element of said ejection failure nozzle to zero. 2. A recording apparatus according to claim 1, wherein said control means does not set the amount of electric power supplied to said electrothermal conversion element of said ejection failure nozzle to 0, but reduces it from said normal amount of electric power. 3. The control means reduces the amount of electric power supplied to the electrothermal conversion element of the defective ejection nozzle from the normal amount instead of setting it to 0 when the defective ejection nozzle is not in the ejection failure state. 4. The recording device according to 3. The recording means performs recording based on image data corresponding to at least one image forming area arranged in the recording medium and a nozzle check pattern arranged outside the image forming area,
The control means sets the amount of electric power supplied to the electrothermal conversion element of the ejection failure nozzle to 0 in printing on the image forming area, and the ejection failure nozzle in at least one of printing of the nozzle check pattern and preliminary ejection. 3. A recording apparatus according to claim 1, wherein the amount of electric power supplied to said electrothermal conversion element is reduced from said normal amount of electric power. The control means is
a defective area identifying means for identifying a defective area including an area where an image is formed by the defective ejection nozzle detected by the detecting means;
imposition means for moving the image forming area to an avoidance position capable of avoiding overlap between the defective area and the image forming area;
6. The recording apparatus according to claim 5, comprising: 3. An amount of electric power supplied to said electrothermal conversion elements of nozzles corresponding to said defective area is reduced from said normal amount of electric power in at least one of printing of said nozzle check pattern and preliminary ejection. 7. The recording device according to 6. The imposition means moves the image forming area to the avoiding position when the avoiding position exists within an image formable area that enables recording on the recording medium,
8. A recording apparatus according to claim 6, wherein said control means performs processing for stopping recording by said recording means when said avoidance position does not exist within said image formable area. When a plurality of image forming areas exist within an image forming area that enables recording on the recording medium, the imposing means causes the image forming area that overlaps the defective area to overlap another image forming area. moving the image forming area to the avoiding position if there is an avoiding position within the image forming area that can be avoided from the defective area without
8. A recording apparatus according to claim 6, wherein said control means performs processing for stopping recording by said recording means when said avoidance position does not exist within said image formable area. When a plurality of image forming areas exist within an image forming area that enables recording on the recording medium, the imposing means causes the image forming area that overlaps the defective area to overlap another image forming area. If an avoidance position that can be avoided from the defective area exists within the image formable area, the image forming area is moved to the avoidance position, and if the avoidance position does not exist within the image formable area 8. A recording apparatus according to claim 6, wherein said plurality of image forming areas are arranged separately on different recording media. The control means is characterized in that a ratio of reducing the amount of electric power supplied to the electrothermal conversion element of the defective ejection nozzle from the normal amount of electric power is determined according to the characteristics of the ink supplied to the defective ejection nozzle. 7. The recording apparatus according to any one of claims 1 to 6. The control means is characterized in that the amount of power supplied to the electrothermal conversion element of the nozzle that ejects a different type of ink from the ink supplied to the ejection failure nozzle does not decrease below the normal amount of power. Item 12. The recording apparatus according to any one of items 1 to 11. The amount of electric power supplied to the electrothermal conversion element of the nozzle corresponds to the supply frequency of electric pulses supplied to the electrothermal conversion element,
13. The apparatus according to any one of claims 1 to 12, wherein said control means reduces the frequency of supplying electrical pulses to said defective ejection nozzles as compared to the frequency of supplying electrical pulses to said normal nozzles. recording device. further comprising transport means for transporting the recording medium in a predetermined transport direction,
14. A recording apparatus according to any one of claims 1 to 13, wherein said recording means comprises a full-line head in which a plurality of said nozzles are arranged along a direction intersecting with said conveying direction. further comprising transport means for transporting the recording medium in a predetermined transport direction,
The recording means performs recording by ejecting ink from the nozzles while moving a recording head having a plurality of nozzles arranged along the transport direction along a direction intersecting the transport direction. 14. The recording apparatus according to any one of claims 1 to 13. a recording step of performing recording on a recording medium by providing a plurality of nozzles having electrothermal conversion elements, and discharging predetermined ink from the nozzles by heat generation of the electrothermal conversion elements;
a detection step of detecting, from among the plurality of nozzles, an ejection failure nozzle in which the predetermined ink ejection is not normally performed due to heat generated by the electrothermal conversion element;
Electric power supplied to the electrothermal conversion element of the ejection failure nozzle is reduced from a normal amount of electric power supplied to the electrothermal conversion element of the normal nozzle that normally ejects the predetermined ink due to the heat generated by the electrothermal conversion element. a control process;
A recording method comprising: A program for causing a computer to execute each step in the recording method according to claim 16.

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